Workbook TP201 EN 541090 Use for intended purpose The training system from Festo Didactic has been developed and produ
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Workbook TP201 EN 541090
Use for intended purpose The training system from Festo Didactic has been developed and produced exclusively for training and further education in the field of automation and technology. The respective training companies and/or trainers must ensure that all trainees observe the safety precautions which are described in this workbook. Festo Didactic hereby excludes any and all liability for damages suffered by trainees, the training company and/or any third parties, which occur during use of the equipment in situations which serve any purpose other than training and/or further education, unless such damages have been caused by Festo Didactic due to malicious intent or gross negligence.
Order no. Status: Authors: Editor: Graphics: Layout:
541090 06/2009 M. Pany, S. Scharf Frank Ebel Doris Schwarzenberger 01/2010
© Festo Didactic GmbH & Co. KG, D-73770 Denkendorf, 2010 Internet: www.festo-didactic.com e-mail: [email protected] The reproduction, distribution and utilisation of this document, as well as the communication of its contents to others without explicit authorisation, is prohibited. Offenders will be held liable for compensation of damages. All rights reserved, in particular the right to file patent, utility model and registered design applications. Portions of this documentation may be duplicated by an authorised user exclusively for training purposes.
Table of Contents Preface _________________________________________________________________________________ V Introduction ____________________________________________________________________________ VII Safety precautions and work instructions ____________________________________________________ VIII Technology module for electro-pneumatics (TP200) ______________________________________________X Learning objectives for the basic level (TP201) _________________________________________________ XI Overview of learning objectives per exercise __________________________________________________ XII Equipment set for the basic level (TP201) ____________________________________________________ XIII Allocation of equipment per exercise _______________________________________________________ XVII Practical tools for the trainer ______________________________________________________________ XVIII Structure of the exercises ________________________________________________________________ XVIII Designations of the components___________________________________________________________ XVIII CD ROM contents ________________________________________________________________________ XIX Equipment set for the advanced level (TP202) _________________________________________________ XXI Learning objectives for the advanced level (TP202)____________________________________________ XXII
Solutions Exercise 1: Inspecting beverage cases _________________________________________________________1 Exercise 2: Opening and closing a supply pipe ________________________________________________ 13 Exercise 3: Sealing plastic cans _____________________________________________________________ 23 Exercise 4: Packing plastic pellets___________________________________________________________ 33 Exercise 5: Diverting packages _____________________________________________________________ 41 Exercise 6: Pushing wooden boards out of a stacking magazine __________________________________ 51 Exercise 7: Sorting packages _______________________________________________________________ 61 Exercise 8: Sanding wooden boards _________________________________________________________ 69 Exercise 9: Diverting bottles _______________________________________________________________ 77 Exercise 10: Stamping taper keys ___________________________________________________________ 87 Exercise 11: Palletising roof tiles ___________________________________________________________ 99 Exercise12: Eliminating a malfunction at a pallet loading station _________________________________ 107
© Festo Didactic GmbH & Co. KG 541090
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© Festo Didactic GmbH & Co. KG 541090
Preface Festo Didactic’s training system for automation and technology is geared towards various educational backgrounds and vocational requirements. The training packages are therefore broken down as follows: Basic modules impart basic, interdisciplinary, technological knowledge. Technology modules address the important topics of open and closed-loop control technology. Function modules explain the fundamental functions of automated systems. Application modules enable training and further education that is aligned to real-life practice. The technology modules deal with various technologies including pneumatics, electro-pneumatics, programmable logic controllers, automation using a personal computer, hydraulics, electro-hydraulics, proportional hydraulics and applications technology (handling).
The modular design of the training system makes it possible to focus on applications above and beyond those covered in the individual modules, such as, for example, PLC actuation of pneumatic, hydraulic and electric drives.
© Festo Didactic GmbH & Co. KG 541090
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All training modules have the same structure: • Hardware • Courseware • Software • Seminars The hardware is comprised of industrial components and systems that are specially designed for training purposes. The structure of the courseware corresponds to that of the training hardware. It includes: • Textbooks (with exercises and examples) • Workbooks (with practical exercises, supplementary instructions and solutions) • Transparencies and videos (for dynamic instruction) The working materials for TP201 consist of 19 exercises and a workbook. Each exercise has its own set of ready-to-use worksheets. The solutions are included in the workbook, which also has the worksheets and a CD ROM. The exercises can be purchased without the workbook and are used as consumables. They can thus be easily made available to trainees. Data sheets for the hardware components are made available along with the training module and on the CD ROM. The teaching and learning media are available in several languages. They’re intended for use in classroom instruction, but are also suitable for self-study. Where software is concerned, computer training programs and programming software are made available for programmable logic controllers. A wide range of seminars covering the contents of the technology module round off the programme for training and further education.
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© Festo Didactic GmbH & Co. KG 540671
Introduction This workbook is part of the training system for automation and technology from Festo Didactic GmbH & Co. KG. The system provides a solid basis for practical training and further education. The TP200 technology module only includes electro-pneumatic control systems. The TP201 basic level is suitable for basic training in the field of electro-pneumatic control technology. It covers the fundamentals of electro-pneumatics as well as the function and use of electro-pneumatic equipment. Simple electro-pneumatic control systems can be set up with the equipment set. The TP202 advanced level is targeted at vocational training in the field of electro-pneumatic control technology. The two equipment sets can be used to set up extensive combinatory circuits with linking of the input and output signals, as well as programme control systems. A permanent workstation equipped with a Festo Didactic profile plate is a prerequisite for setting up the control systems. The profile plate has 14 parallel T-slots at 50 mm intervals. A power supply with shortcircuit protection is used as a direct voltage source (input: 230 V, 50 Hz, output: 24 V, max. 5 A). A portable compressor with silencer (230 V, max. 8 bar = 800 kPa) can be used for compressed air supply. Working pressure should not exceed 6 bar (600 kPa).
Ideal reliability can be achieved by operating the control system at a working pressure of 5 bar (500 kPa) without oil. All the control systems for the 12 exercises are set up using the equipment set for the TP201 basic level. The theoretical fundamentals for understanding this collection of exercises are included in the textbook: •
Electro-pneumatics
Data sheets for the individual components are also available (cylinders, valves, measuring instruments etc.).
© Festo Didactic GmbH & Co. KG 541090
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Safety precautions and work instructions
General Trainees should only work with the control systems under the supervision of a trainer. Observe specifications included in the data sheets for the individual components and in particular all safety instructions!
Mechanical • Mount all of the components securely onto the profile plate. • Limit switches may not be actuated frontally. • Danger of injury during troubleshooting! • Use a tool to actuate the limit switches, for example a screwdriver. • Only reach into the set-up when it’s at a complete standstill.
Electrical • Electrical connections must only be established and interrupted in the absence of voltage! • Use connector cables with safety plugs only for electrical connections. • Use low-voltage only (max. 24 V DC).
Pneumatics • Do not exceed the maximum permissible pressure of 6 bar (600 kPa). • Do not switch on the compressed air until all the tubing connections have been completed and secured. • Do not disconnect tubing while under pressure. • Danger of injury when switching compressed air on! Cylinders may advance and retract automatically. • Danger of accident due to tubing slipping off! Use shortest possible tubing connections. Wear safety glasses. In the event that tubing slips off: Switch compressed air supply off immediately. • Pneumatic circuit set-up: Connect the components using plastic tubing with an outside diameter of 4 or 6 mm. Push the tubing into the push-in connector as far as it will go. Switch compressed air supply off before dismantling the circuit. • Dismantling pneumatic circuits: Press the blue release ring down, after which the tubing can be pulled out.
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© Festo Didactic GmbH & Co. KG 540671
The mounting boards for the components are equipped with mounting variants A through D: Variant A, snap-in system Lightweight components that are not load-bearing (e.g. directional control valves). Simply clip the component into the slot on the profile plate. Release the component from the slot by actuating the blue lever. Variant B, bolt system Components with medium load capacity (e.g. drives). These components are clamped to the profile plate using T-head bolts. The blue, knurled nut is used for clamping and loosening. Variant C, screw system For components with high load capacity and components which are seldom removed from the profile plate (for example on-off valve with filter regulator). These components are secured with socket head screws and T-head bolts. Variant D, plug-in system Lightweight components with locking pins that are not load-bearing (e.g. indicators). These are secured using plug adapters. Observe specifications in the data sheets regarding the individual components.
© Festo Didactic GmbH & Co. KG 540671
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Technology module for electro-pneumatics (TP200) The TP200 technology packet consists of a multitude of training materials and seminars. The subject matter is entirely focused on electro-pneumatic control systems. Individual components included in the TP200 technology module can also be included in any of the other modules. Important elements of the TP200: • Permanent workstation with Festo Didactic profile plate • Compressor (230 V, 0.55 kW, max. 8 bar = 800 kPa) • Equipment sets or individual components • Optional training materials • Practical training models • Complete laboratory set-ups Training documentation Textbooks
TP201 basic level Fundamentals of pneumatic control technology Maintenance of pneumatic equipment and systems
Workbooks
Optional courseware
TP201 basic level TP202 advanced level Set of transparencies and overhead projector Magnetic symbols, drawing template Electro-pneumatics WBT, pneumatics WBT Electrical engineering WBTs 1 and 2, electronics WBTs 1 and 2 Set of cutaway models with storage case FluidSIM® pneumatic simulation software
Seminars P100
Basic pneumatics knowledge for machine operators
P111
Fundamentals of pneumatics and electro-pneumatics
P121
Maintenance and troubleshooting for pneumatic and electro-pneumatic systems
P-OP
Tracking down waste – economic use of pneumatics
P-NEU
Pneumatics refresher and update
IW-PEP
Repair and maintenance in the field of control technology – pneumatic and electro-pneumatic systems
P-AL
Pneumatics for further education
P-AZUBI
Pneumatics and electro-pneumatics for trainees
Please refer to the current seminar planner for locations, dates and prices. You’ll find further training materials in our catalogue and on the Internet. The training system for automation and technology is continuously updated and expanded. Transparencies, videos, CD ROMs and DVDs, as well as textbooks, are offered in several languages.
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© Festo Didactic GmbH & Co. KG 540671
Learning objectives for the basic level (TP201) • • • • • • • • • • • • • • • • • • • •
Become familiar with the set-up and mode of operation of a single-acting cylinder. Become familiar with the set-up and mode of operation of a double-acting cylinder. Be able to calculate piston forces based on specified values. Become familiar with the set-up and mode of operation of a 3/2-way solenoid valve. Become familiar with the set-up and mode of operation of a double solenoid valve. Be able to select solenoid valves based on the specified requirements. Be able to recognise and sketch the various types of actuation for directional control valves. Be able to convert solenoid valves. Be able to explain and set up direct actuation. Be able to explain and set up indirect actuation. Become familiar with logic operations and be able to set them up. Become familiar with various types of end-position control and learn to select the appropriate type. Be able to calculate characteristic electrical values. Become familiar with latching circuits with varying performance features. Be able to explain and set up an electrical latching circuit with dominant shutdown signal. Be able to set up a pressure-dependent control system. Become familiar with the set-up and mode of operation of magnetic proximity switches. Become familiar with displacement-step diagrams and learn to create them for specific problems. Be able to implement sequence control with two cylinders. Be able to detect and eliminate errors in simple electro-pneumatic control systems.
© Festo Didactic GmbH & Co. KG 541090
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Overview of learning objectives per exercise Exercise
1
2
3
•
•
4
5
6
7
8
9
10
11
12
Learning objectives Become familiar with the set-up and mode of operation of a single-acting cylinder.
•
Become familiar with the set-up and mode of operation of a double-acting cylinder.
•
Learn to calculate piston forces based on specified values. Become familiar with the set-up and mode of operation of a 3/2-way valve.
• •
Become familiar with the set-up and mode of operation of a double solenoid valve.
•
Be able to select solenoid valves based on the specified requirements. Be able to recognise and sketch the various types of actuation for directional control valves.
• • •
Be able to convert solenoid valves. Be able to explain and set up direct actuation. Be able to explain and set up indirect actuation.
•
• •
•
Become familiar with various types of end-position control and learn to select the appropriate type. Become familiar with logic operations and be able to set them up. Be able to calculate characteristic electrical values.
• •
•
• • •
Become familiar with latching circuits with varying performance features.
•
Be able to explain and set up an electrical latching circuit with dominant breaking signal.
•
Be able to set up a pressure-dependent control
•
system.
•
Become familiar with the set-up and mode of operation of magnetic proximity switches.
•
Become familiar with displacement-step diagrams and learn to create them for specific problems.
•
Be able to implement sequence control with two
•
cylinders. Be able to detect and eliminate errors in simple electro-pneumatic control systems.
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•
•
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Equipment set for the basic level (TP201) The equipment set has been put together for basic training in the field of electro-pneumatic control technology. It includes all the elements that are necessary for mastering the specific learning objectives and can be supplemented with any other equipment sets. A profile plate, an electrical power supply unit and a source of compressed air are also required in order to set up functional control systems. Equipment set for the basic level (TP201) Designation
Order no.
Quantity
2 x 3/2-way solenoid valve, normally closed
539776
1
5/2-way double solenoid valve
539778
2
5/2-way solenoid valve
539777
1
Blanking plug
153267
10
Double-acting cylinder
152888
2
One-way flow control valve
193967
4
Pressure sensor
539757
1
Single-acting cylinder
152887
1
On-off valve with filter regulator
540691
1
Limit switch, electrical, actuated from left
183322
1
Limit switch, electrical, actuated from right
183322
1
Plastic tubing, 4 x 0.75, 10 m
151496
2
Proximity switch, electronic
540695
2
Proximity switch, optical
178577
1
Relay, 3-way
162241
2
Signal input, electrical
162242
1
Push-in sleeve
153251
10
Push-in T-connector
153128
20
Distributor block
152896
1
© Festo Didactic GmbH & Co. KG 541090
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Equipment set symbols Designation
Symbol
Relay, 3-way
A1
12 14
22 24
32 34
42 44
11
21
31
41
12 14
22 24
32 34
42 44
11
21
31
41
12 14
22 24
32 34
42 44
11
21
31
41
A2 A1
A2 A1
A2
Signal input, electrical
13
21
14
22
13
21
14
22
3/2-way solenoid valve, normally closed
13
21
14
22
13
21
14
22
12 1M1
2
1
3
1M1
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© Festo Didactic GmbH & Co. KG 541090
Designation
Symbol
5/2-way double solenoid valve
5/2-way solenoid valve
Proximity switch, electronic
Pressure sensor p
Proximity switch, optical
Electrical limit switch 2
4 1
One-way flow control valve
1
© Festo Didactic GmbH & Co. KG 541090
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Designation
Symbol
Single-acting cylinder
Double-acting cylinder
On-off valve with filter regulator
1 2
3
Distributor block
Connectors
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© Festo Didactic GmbH & Co. KG 541090
Allocation of equipment per exercise Exercise
1
2
3
4
5
6
7
8
9
10
11
12
1
1
Components Cylinder, single-acting
1
Cylinder, double-acting One-way flow control valve
1
3/2-way solenoid valve, normally closed
1
5/2-way solenoid valve
1 1
1
2
2
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
3
3
1
1
1
1
1
2
1
1
1
1
1
(1) 1
1
1
5/2-way double solenoid valve
1 1
1
1
1
Pressure sensor
1 1
Limit switch, electrical
1
2
Proximity switch, normally open
2
2
Proximity switch, optical Pushbutton, electrical, normally open
1
1
1
2
2
1
1
Pushbutton, electrical, normally closed Relay
1
1
1
1
1
1
2
2
3
1
3
3
3
3
Distributor block
1
1
1
1
1
1
1
1
1
1
1
1
On-off valve with filter regulator
1
1
1
1
1
1
1
1
1
1
1
1
Power supply unit, 24 V DC
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
5/2-way solenoid valve
© Festo Didactic GmbH & Co. KG 541090
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Practical tools for the trainer Learning objectives The basic learning objectives for the exercises in this module are the systematic sketching of circuit diagrams as well as the practical set-up of a control system on the profile plate. This direct interaction involving both theory and practice ensures faster, long-term learning. Each exercise has its own individual learning objectives; the specific learning objectives are documented in the matrix. Required time The time required for the exercises depends on the trainee’s previous knowledge of the subject matter. For training a skilled labourer in metalworking or electrical installation: approx. 2 weeks. For training a technician or engineer: approx. 1 week. Equipment sets The exercises and the equipment sets match each other. For all the exercises you’ll only need the components included in the equipment set for the TP201 basic level. Each exercise in the basic level can be set up on a profile plate.
Structure of the exercises All 12 exercises in part A have the same structure and are broken down into: • Title • Learning objectives • Presentation of the problem • Layout • Parameters • Project assignment • Worksheets The solutions for all the 12 exercises are included in the trainer’s manual.
Designations of the components Pneumatic components are designated in circuit diagrams to DIN ISO 1219 2. All the components included in any given circuit have the same primary identifying number. Letters are assigned depending on each respective type of component. Consecutive numbers are assigned if several components of the same type are included within a single circuit. Pressure lines are designated with a P and are numbered separately. Drives: Valves: Sensors: Signal input: Accessories: Pressure lines:
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1A1, 2A1, 2A2 ... 1V1, 1V2, 1V3, 2V1, 2V2, 3V1 ... 1B1, 1B2 ... 1S1, 1S2 ... 0Z1, 0Z2, 1Z1 ... P1, P2 ...
© Festo Didactic GmbH & Co. KG 540671
CD ROM contents The CD ROM provides you with additional media. The contents of parts A (exercises) and C (solutions) have been saved as PDF files. The CD ROM has the following structure: • Operating instructions • Data sheets • Demo • Festo catalogue • FluidSIM® circuit diagrams • Industrial applications • Presentations • Product information • Videos Operating instructions Operating instructions for various components included in the technology module are available. These instructions are helpful when using and commissioning the equipment. Data sheets The data sheets for the components included in the technology module are available as PDF files. Demo A demo version of the FluidSIM® pneumatics software package is included on the CD ROM. Even this demo version is suitable for testing control systems developed by the user. Festo catalogue The relevant pages from the Festo catalogue will be provided with selected components. The representations and descriptions of the components are intended to demonstrate how the components are presented in an industrial catalogue. Additional information regarding the components is also included. FluidSIM® circuit diagrams The FluidSIM® circuit diagrams for all 12 exercises included in the technology module are contained in this directory. Industrial applications Photos and graphics representing industrial applications are made available. These can be used to illustrate individual tasks. Project presentations can also be supplemented with these illustrations. Presentations Contains short presentations of the components included in the technology module. These can be used, for example, to create project presentations.
© Festo Didactic GmbH & Co. KG 541090
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Product information This directory contains product information and data sheets from Festo AG & Co. KG for the components included in this technology module. This is intended to demonstrate which information and data are available for industrial components. Videos Several videos of industrial applications complete the media provided with the technology module. Short clips demonstrate the applications in their actual industrial environments.
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© Festo Didactic GmbH & Co. KG 540671
Equipment set for the advanced level (TP202) The equipment set for the advanced level has been put together for vocational training in the field of electropneumatic control technology. The two equipment sets (TP201 and TP202) include components that are necessary for mastering the predefined learning objectives and can be supplemented as required with other equipment sets from the training system for automation and technology. Equipment set for the advanced level (TP202, order no. 540713) Quantity
Designation
Order no.
2
Relay, 3-way
162241
1
Signal input, electrical
162242
1
Time relay, 2-way
162243
1
Preset counter, electrical
162355
1
Proximity switch, inductive
178574
1
Proximity switch, capacitive
178575
1
Emergency-stop button
183347
1
Valve terminal with 4 valve slices (MMJJ)
540696
2
Non-return valve, piloted
540715
© Festo Didactic GmbH & Co. KG 541090
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Learning objectives for the advanced level (TP202) • • • • • • • • • • •
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Describe the structure and application of valve terminals Implement sequence controls with overlapping signals – solution according to group method Implement sequence controls with overlapping signals – solution with step sequence using spring return valves Implement sequence controls with overlapping signals – solution with step sequence using double pilot valve (with control step) Describe and set up modes of operation (single/continuous cycle) Describe the function and application of a preset counter Explain and implement the emergency stop function with spring return valves Implement special emergency stop conditions: actuators must come to a standstill during an emergency stop Explain function and use of a 5/3-way solenoid valve Describe and set up the “Set” operating mode Execute troubleshooting in complex electro-pneumatic circuits
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases Learning objectives After completing this exercise: • You’ll be familiar with the set-up and mode of operation of a single-acting cylinder. • You’ll be familiar with the set-up and mode of operation of a 3/2-way solenoid valve. • You’ll be able to recognise and sketch the various types of actuation for directional control valves. • You’ll be able to explain and set up direct actuation.
Presentation of the problem Beverage cases are inspected for completeness with a test device. Incomplete cases are pushed off of the roller conveyor by pressing a pushbutton. Develop a control system with which this process can be executed.
Layout
Test device
© Festo Didactic GmbH & Co. KG 541090
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Exercise 1: Inspecting beverage cases
• • •
2
Control sequence After pressing a pushbutton, the piston rod of a single-acting cylinder pushes the beverage case from the conveyor. When the pushbutton is released, the piston rod moves to its retracted end position.
1 2 3 4 5
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
1
2
Parameters A single-acting cylinder is to be used. The cylinder will be actuated using a pushbutton. In the event of a power failure, the cylinder’s piston rod should move to the retracted end position.
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases
Function of pneumatic power components Pneumatic power components can be subdivided into two groups: • Power components with straight motion • Power components with rotary motion –
Describe the power components shown below, as well as their functions.
Symbol
Function Single-acting cylinder, reset spring in piston chamber, return stroke by means of compressed air, forward stroke by means of reset spring. Function The piston rod of this single-acting cylinder moves to its retracted end position by activating the compressed air. After deactivating the compressed air, the piston moves to its advanced end position by a reset spring in the piston chamber (2 operating positions). Single-acting cylinder, reset spring in piston chamber, forward stroke by means of compressed air, return stroke by means of reset spring. Function The piston rod of the single-acting cylinder moves to its advanced end position when the compressed air has been activated. After deactivating the compressed air, the piston moves to its retracted end position by a reset spring (2 operating positions). Pneumatic quarter turn actuator (rotary drive) with limited swivel angle Function This swivel cylinder is double-acting and reverses by alternately activating the compressed air at either end (2 operating positions).
© Festo Didactic GmbH & Co. KG 541090
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Exercise 1: Inspecting beverage cases
Complete the symbols for solenoid valves –
Complete the individual symbols with the help of the descriptions of the respective components.
Description
Symbol
Directly actuated 3/2-way solenoid valve, normally open,
2
with manual override, spring return
10 1M1
1
3
Pilot actuated 3/2-way solenoid valve, normally closed,
2
with manual override, spring return
12 1M1
4
1
3
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases
Normal positions of directional control valves An electrically actuated 3/2-way solenoid valve has two switching positions. It can be in the normal position (unactuated) or the switched position (actuated). The valve can be either closed or open in its normal position. The single-acting cylinder depicted below is controlled by an electrically actuated 3/2-way solenoid valve. –
Describe how the two different normal positions affect the motion sequence of the cylinder shown below:
3/2-way solenoid valve, normally closed
3/2-way solenoid valve, normally open
The solenoid valve used is reversed by applying voltage to the
The solenoid valve used is reversed by applying voltage to the
solenoid coil; flow is enabled from supply port 1 to working port
solenoid coil; supply port 1 is closed, thus stopping flow. After
2. After the signal has been stopped, the valve returns to its
stopping the signal, the valve returns to its normal position by a
normal position by a reset spring and supply port 1 is closed, thus reset spring and flow from supply port 1 to working port 2 is stopping flow. If the directional control valve’s solenoid coil is de- enabled. If the directional control valve’s solenoid coil is deenergised, the cylinder chamber is vented via exhaust port 3 at
energised, the cylinder chamber is pressurised via the directional
the directional control valve. The piston rod is retracted. When
control valve. The piston rod is advanced. When the solenoid coil is
the solenoid coil is energised, the directional control valve
energised the directional control valve switches and the cylinder
switches and the cylinder chamber is pressurised. The piston rod
chamber is exhausted via exhaust port 3 at the directional control
advances. When the solenoid coil is de-energised, the valve
valve. The piston rod is retracted. When the solenoid coil is de-
switches back again. The cylinder chamber is exhausted and the
energised, the valve switches back again. The cylinder chamber is
piston rod is retracted. The motion sequence is thus as follows: 1A1+ 1A1-.
pressurised and the piston rod is advanced. The motion sequence is thus as follows: 1A1- 1A1+.
© Festo Didactic GmbH & Co. KG 541090
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Exercise 1: Inspecting beverage cases
Direct and indirect actuation An electrically actuated solenoid valve can be directly or indirectly actuated. –
Describe the difference on the basis of the following example: electrical actuation of a 3/2-way solenoid valve with spring return using a pushbutton.
Direct actuation
Indirect actuation
When the pushbutton is activated, current flows through the
In the case of indirect actuation, current flows through a relay coil
valve’s solenoid coil. The solenoid is energised and the valve
when a pushbutton is activated. The relay’s contacts are closed
switches to the actuated position.
and the valve switches. The valve remains in this switching
The flow of electrical current is interrupted when the pushbutton
position as long as electrical current flows through the solenoid
is released. The solenoid is de-energised and the valve switches to the normal position.
coil or the relay coil. The relay drops out when the flow of electrical current through the relay coil is interrupted and the valve switches to its normal position. More complicated indirect actuation is used when the control circuit and the primary circuit use different voltages, when current flowing through the directional control valve’s solenoid coil is greater than permissible current for the pushbutton, when several valves are switched with a single pushbutton or pressure switch or if extensive logic operations are required amongst the signals from various pushbuttons.
6
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases
Design and function of electrical switches In principle, switches are subdivided into two types, namely pushbuttons and control switches and function as NC contacts, NO contacts or change-over contacts. –
Describe the design and function of the switches depicted below.
Symbol
Design / function Design: Pushbutton with normally open contacts
3 4
Function: In the case of a pushbutton, the selected switching position is only retained as long as the pushbutton is activated. The pushbutton shown here has a normally open function. With normally open contacts, the electrical circuit is interrupted when the pushbutton is in its normal position, i.e. in the unactivated state. When the control stem is actuated, the electrical circuit is closed and current flows to the consuming device. When the control stem is released, the pushbutton is returned to its normal position by means of spring force and the electrical circuit is interrupted. Design: Control switch with normally closed contacts Function: Control switches are mechanically locked into the two switching positions. The respective switching position is retained until the switch is once again activated. The control switch shown here has a normally closed function. In the case of normally closed contacts, the electrical circuit is closed when the control switch is held in its normal position by means of spring force. When the control switch is activated, the electrical circuit is interrupted and reactivation closes the circuit again. Design: Pushbutton with change-over contacts
2
4 1
Function: In the case of a pushbutton, the selected switching position is only retained as long as the pushbutton is activated. The pushbutton shown here has a change-over function. In the case of change-over contacts, NC and NO functions are combined into a single component. An electrical circuit is closed and another is interrupted with a single switching operation. Both circuits are briefly interrupted during switching.
© Festo Didactic GmbH & Co. KG 541090
7
Exercise 1: Inspecting beverage cases
Mode of operation of various valve types Electrically actuated directional control valves are switched by means of solenoids. In principle, they can be subdivided into two groups: • Solenoid valves with spring return • Double solenoid valves –
Explain the difference between the two groups with regard to function and performance in the event of a power failure.
Valve type
Mode of operation
Solenoid valve with spring return
The actuated switching position is only retained as long as electrical current flows through the solenoid coil. The normal position is clearly defined by the reset spring. If there is no electrical power, the valve returns to its normal position by the spring. This may cause dangerous machine motion. For example, the piston rod of a pneumatic cylinder could be returned to its normal position, thus releasing a previously clamped workpiece.
Double solenoid valve
Only a brief signal is required in order to reverse the valve and the last switching position is retained even in the de-energised state as the result of static friction. All solenoid coils are de-energised in the normal position and the normal position cannot be clearly defined. The valve stays in its last switching position in the event of a power failure. No dangerous machine motion can be triggered as a result. For example, the piston rod of a pneumatic cylinder is kept in its operating position and workpiece clamping is thus retained.
8
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases
Identifying valve ports In order to prevent incorrect tubing connections at directional control valves, the valve ports (working and pilot lines) are identified in accordance with ISO 5599-3 on the valves themselves, as well as in the circuit diagram. –
Explain the meanings and functions of the port designations listed below.
Port identification
Meaning and function
3
Exhaust port
12
Pilot line, function for pilot actuated or pneumatically actuated directional control valves when actuated: supply port 1 and working port 2 are connected
10
Pilot line, function for pilot actuated or pneumatically actuated directional control valves when actuated: supply port 1 is closed
© Festo Didactic GmbH & Co. KG 541090
9
Exercise 1: Inspecting beverage cases
Complete the pneumatic and electrical circuit diagrams –
Complete the pneumatic and electrical circuit diagrams for the sorting system. 1A1 +24 V
1V2
1
13
2 S1
14
1 1V1 1M1
2
1
3 1M1
0V Pneumatic circuit diagram
10
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 540671
Exercise 1: Inspecting beverage cases
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, single-acting
1
One-way flow control valve
1
3/2-way solenoid valve, normally closed
1
Pushbutton (normally open)
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
© Festo Didactic GmbH & Co. KG 541090
11
Exercise 1: Inspecting beverage cases
12
© Festo Didactic GmbH & Co. KG 540671
Exercise 2: Opening and closing a supply pipe Learning objectives After completing this exercise: • You’ll be familiar with the set-up and mode of operation of a double-acting cylinder. • You’ll be able to explain and set up direct actuation.
Presentation of the problem Numerous pipes have to be opened and closed in a water treatment system with the help of shut-off components. During the test set-up an actuation option for the shut-off valve will be sought.
Layout
Shut-off device
© Festo Didactic GmbH & Co. KG 541090
13
Exercise 2: Opening and closing a supply pipe
14
• • •
Parameters A double-acting cylinder will be used. The cylinder will be actuated using a pushbutton. In the event of a power failure, the cylinder’s piston rod should move to its retracted end position.
1 2 3 4 5 6
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
1 2
Control sequence The gate is opened when a pushbutton is pressed. When the pushbutton is released, the gate is closed again.
© Festo Didactic GmbH & Co. KG 540671
Exercise 2: Opening and closing a supply pipe
Comparing directly actuated and pilot actuated valves With regard to the type of valve piston actuation, differentiation is made between directly actuated and pilot actuated solenoid valves. –
Compare these two valve types and list their respective advantages and disadvantages.
Directly-actuated valve
Pilot-actuated valve
Flow to the consuming device is enabled by the solenoid’s
Flow to the consuming device is switched by the primary stage. The
armature. A relatively large armature is required in order to
valve piston is set into motion by means of an air duct from supply
ensure an adequately large cross section for the opening, thus
port 1.
allowing for sufficient flow. Hence a correspondingly powerful
This only requires minimal flow so that a relatively small armature
reset spring is required and the solenoid must also generate
with minimal actuating force can be used. Only minimal supply
considerable force. The solenoid is thus large and has high power pressure is required in order to actuate the piston against the consumption. force of the spring. A smaller solenoid can be used than that required for a directly actuated valve. Power consumption and heat emission are less.
© Festo Didactic GmbH & Co. KG 541090
15
Exercise 2: Opening and closing a supply pipe
Identify valve ports In order to prevent incorrect tubing of directional control valves, the valve ports (working and pilot lines) are identified in accordance with ISO 5599-3 on the valves themselves, as well as in the circuit diagram. –
Explain the meanings and functions of the designations listed below.
Designation
Meaning and function 4
Working line, consumer port
14
Pilot line, function for pilot actuated or pneumatically actuated directional control valves when actuated: supply port 1 and consumer port 4 are connected
82/84
16
Pilot line, function for pilot actuated or pneumatically actuated directional control valves when actuated: auxiliary pilot air exhaust
© Festo Didactic GmbH & Co. KG 540671
Exercise 2: Opening and closing a supply pipe
Mode of operation of a solenoid valve A valve symbol indicates how the valve functions, i.e. how many ports it has, its switching positions and the type of actuation, but it says nothing about its constructional design. 4
2
1M1 5
–
1
3
Describe the mode of operation of the directional control valve shown above. The valve is a pilot actuated 5/2-way solenoid valve with manual override and spring return. Mode of operation: The piston is at the left-hand limit stop when the valve is in its normal position and ports 1 and 2 (supply port and consumer port), as well as ports 4 and 5 (consumer port and exhaust port), are connected. If the solenoid coil is energised, the valve piston moves to the right-hand limit stop. In this position, ports 1 and 4, as well as 2 and 3 (exhaust port) are connected (the internal pilot line for pilot control is designated 14, function when actuated: supply port 1 and consumer port 4 are connected). When the solenoid coil is de-energised, the valve piston is returned to its normal position by means of spring force and pilot air is vented. In the de-energised state, the valve can be switched by means of manual override.
© Festo Didactic GmbH & Co. KG 541090
17
Exercise 2: Opening and closing a supply pipe
IP designation Depending on installation circumstances and ambient conditions, electrical operating equipment is protected by housings and covers. The required degree of protection against dust, moisture and foreign matter must be specified. The designation IP 65 appears on a solenoid coil. –
Explain the meaning of this designation. The designation for a degree of protection in accordance with DIN-VDE 470-1 consists of the two letters IP (International Protection) and two numbers. The first number indicates the degree of protection against the ingress of foreign matter and the second number specifies the degree of protection against moisture and water. And thus the designation IP 65 means protection against the ingress of dust (i.e. complete protection against contact with energised components and internal moving parts, protection against the ingress of dust) and water jets (i.e. water jets sprayed at the housing from all directions should not cause any damage).
18
© Festo Didactic GmbH & Co. KG 540671
Exercise 2: Opening and closing a supply pipe
Symbols for pneumatic cylinders Cylinders with piston rods which move in straight lines can be subdivided into two groups. • Single-acting cylinders • Double-acting cylinders –
Explain the meanings of the cylinder symbols shown below. Symbol
Meaning Symbol 1 Double-acting multi-position cylinder, reversed by alternately pressurising the respective ends with compressed air. Travel to 3 positions is made possible by connecting 2 cylinders with the same piston diameter but different stroke lengths. Direct travel to the third position is possible from the first position, or it can be approached via the intermediate (second) position. However, the downstream cylinder stroke must always be larger than the upstream stroke. During the return stroke, travel to an intermediate position is only possible with corresponding actuation (3 operating positions). The shorter stroke length is half the length of the longer stroke. Symbol 2 Double-acting cylinder, reversed by alternately pressurising the respective ends with compressed air, adjustable end-position cushioning (2 operating positions). If large loads are moved by a cylinder, cushioning is used in the end position. Before reaching the end position, a cushioning piston prevents exhausting the air directly into the atmosphere. The trapped exhaust air reduces piston speed during the last part of the stroke.
© Festo Didactic GmbH & Co. KG 541090
19
Exercise 2: Opening and closing a supply pipe
Complete the pneumatic and electrical circuit diagrams –
Complete the pneumatic and electrical circuit diagrams for the sorting system. 1A1 +24 V
1V2
1
1
1
13
1V3
S1 14
2 1V1
2
4
2
5
3
1M1
1M1 1
0V
Pneumatic circuit diagram
20
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 540671
Exercise 2: Opening and closing a supply pipe
Sequence description –
Describe the control system’s operating sequence. Initial position The cylinder is in the retracted end position.
Step 1-2 After activating pushbutton S1 (NO contact), solenoid coil 1M1 at 5/2-way solenoid valve 1V1 is energised. Valve 1V1 is reversed. The piston end of cylinder 1A1 is now filled with compressed air and the piston rod end is exhausted. Cylinder 1A1 advances.
Step 2-3 As soon as pushbutton S1 (NO contact) is no longer actuated, coil 1M1 is de-energised, valve 1V1 is returned to its initial position by the reset spring, the piston end of cylinder 1A1 is exhausted and the piston rod end is filled with compressed air. The cylinder returns to its retracted end position.
© Festo Didactic GmbH & Co. KG 541090
21
Exercise 2: Opening and closing a supply pipe
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way solenoid valve
1
Pushbutton (normally open)
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
1
Cylinder, double-acting
Equipment list
22
© Festo Didactic GmbH & Co. KG 540671
Exercise 3: Sealing plastic cans Learning objectives After completing this exercise: • You’ll be familiar with the set-up and mode of operation of double-acting cylinders. • You’ll be able to make use of indirect electrical actuation.
Presentation of the problem At a filling system plastic cans with wall and ceiling paint. After filling, lids are pressed onto the plastic buckets.
Layout
Can filling
© Festo Didactic GmbH & Co. KG 541090
23
Exercise 3: Sealing plastic cans
• •
24
Parameters A double-acting cylinder will be used. The cylinder will be actuated indirectly and using a pushbutton. In the event of a power failure, the cylinder’s piston rod should move to its retracted end position.
1 2 3 4 5
Project assignment Answer the questions and complete the tasks for learning topics. Draw the pneumatic and electrical circuit diagrams. Create an equipment list. Set up the control system, both pneumatically and electrically and describe the control sequence. Double check the control sequence.
1 2
Control sequence The press-on stamp is advanced after pressing a pushbutton and the lid is pressed into place. When the pushbutton is released, the stamp is returned to its initial position.
© Festo Didactic GmbH & Co. KG 540671
Exercise 3: Sealing plastic cans
Mode of operation of a relay Relays are part of the units in the signal processing section. Their essential components include: • Coil with core • Coil winding • Set of contacts • Retracting spring • Armature • Terminal lugs The following graphic is a sectional view of a relay. 2
3
1 4 5
A1 A2
4 2
1
7
6
Sectional view of a relay
–
Match up the numbers in the above graphic to the components in the table below.
Number
Component
7
Terminal lugs
3
Coil winding
5
Set of contacts
2
Retracting spring
4
Armature
6
Terminal lugs
1
Coil with core
© Festo Didactic GmbH & Co. KG 541090
25
Exercise 3: Sealing plastic cans
Set-up and mode of operation of a relay –
Describe the mode of operation of a relay. A relay is an electromagnetically actuated switch. An electromagnetic field is generated when the coil is energised. This in turn draws the moving armature towards the core. The armature acts on the relay’s contacts, which are then opened or closed depending on the relay’s configuration. When the flow of electrical current to the coil is interrupted, a spring causes the armature to return to its initial position.
26
© Festo Didactic GmbH & Co. KG 540671
Exercise 3: Sealing plastic cans
Set-up and mode of operation of a relay One or more contacts can be switched with a single relay coil. Depending on the required function, relays with normally closed, normally open or change-over contacts are used. –
Describe the layouts, contact types and functions of the relays shown in the table.
Description
Symbol
Layout, contact type: Relay with two NC contacts and two NO contacts Function: When the relay is energised, up to two current paths are interrupted and up to two additional current paths are closed by the four relay contacts. Layout, contact type: Relay with four change-over contacts
A1
12 14
22 24
32 34
42 44
11
21
31
41
Function: When the relay is energised, up to four current paths are opened or closed by the four relay contacts. Great flexibility and a wide variety of contact combinations are possible.
© Festo Didactic GmbH & Co. KG 541090
A2
27
Exercise 3: Sealing plastic cans
Set-up and mode of operation of a relay –
Write down the different ways in which relays can be used in electrical and electro-pneumatic control systems. Signal multiplying Voltage and current amplification Delaying and conversion of signals Linking of information Interruption of the control circuit and the primary circuit Interruption of DC and AC circuits in strictly electrical control systems
28
© Festo Didactic GmbH & Co. KG 540671
Exercise 3: Sealing plastic cans
Complete the pneumatic and electrical circuit diagrams –
Complete the pneumatic and electrical circuit diagrams for the lid press by completing the circuit diagram below and adding the component and port designations. +24 V
1
2
13
1A1
12 K1
S1
11
14
1V2
1
1
14
1V3 A1 K1
2 1V1
2
4
2
1M1 5
1M1 A2
1
3
Pneumatic circuit diagram
© Festo Didactic GmbH & Co. KG 541090
0V 11
12 14 .2
21
22 24
31
32 34
41
42 44
Electrical circuit diagram
29
Exercise 3: Sealing plastic cans
Sequence description –
Set up the control system and describe its operating sequence. Initial position Cylinder 1A1 is in the retracted end position.
Step 1-2 After activating pushbutton S1 (NO contact) relay K1 is energised, change-over contact K1 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way valve 1V1 is energised. Valve 1V1 is reversed. The rear chamber of cylinder 1A1 is now filled with compressed air and the front chamber is exhausted. Cylinder 1A1 advances.
Step 2-3 As soon as pushbutton S1 (NO contact) is no longer activated, relay K1 is de-energised and change-over contact K1 (connected as an NO contact) is opened. Coil 1M1 is de-energised as a result and valve 1V1 is returned to its initial position by the reset spring. The rear chamber of cylinder 1A1 is exhausted and the front chamber is filled with compressed air. The cylinder returns to its retracted end position.
30
© Festo Didactic GmbH & Co. KG 540671
Exercise 3: Sealing plastic cans
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components and their quantities in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way solenoid valve
1
Pushbutton (normally open)
1
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
© Festo Didactic GmbH & Co. KG 541090
31
Exercise 3: Sealing plastic cans
32
© Festo Didactic GmbH & Co. KG 540671
Exercise 4: Packing plastic pellets Learning objectives After completing this exercise: • You’ll be able to set up indirect actuation. • You’ll be familiar with logic operations. • You’ll be able to select solenoid valves based on the specified requirements. • You’ll be able to convert solenoid valves
Presentation of the problem Plastic pellets need to be packed from a storage silo. The silo is opened and closed with a flap. The process will be started from two locations.
Layout
Packing plastic pellets
© Festo Didactic GmbH & Co. KG 541090
33
Exercise 4: Packing plastic pellets
• • •
Parameters A single-acting cylinder is to be used. The cylinder will be actuated indirectly and using a pushbutton. In the event of a power failure, the cylinder’s piston rod should advance to the advanced end position.
1 2 3 4 5 6
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
1 2
34
Control sequence The flap is opened by pressing either one of two pushbuttons and the material slides out of the container. When the pushbutton is released, the flap is closed.
© Festo Didactic GmbH & Co. KG 541090
Exercise 4: Packing plastic pellets
Converting solenoid valves A great many demands are placed on valves in actual industrial use. If a valve with all of the desired characteristics is not available, a valve with a different number of ports can often be used in order to fulfil the specified function. The following table shows a selection of directional control valves which are frequently used in industrial applications. 4
2
14 1M1 5
–
3
1
Describe the valve types depicted in the table below. Tick off all the solenoid valves which can be replaced by a 5/2-way valve of the type shown above. If conversion is required in order to fulfil the required function, describe the work to be done.
Symbol
Description: valve type
Replacement possible
Pilot actuated 2/2-way solenoid valve with 2
Replacement possible, no conversion required?
spring return and manual override X
12 1M1
1
2 12 1M1
1
Pilot actuated 3/2-way solenoid valve with
Replacement possible,
spring return and manual override, normally closed
conversion: close consumer port 2 with a blanking plug
X
3
Pilot actuated 3/2-way solenoid valve with 2 10 1M1
1
4 14 1M1
Description: required conversion
spring return and manual override, normally open
Replacement possible, no conversion required X
3
2
Pilot actuated 4/2-way solenoid valve with spring return and manual override
Replacement possible, X
1
conversion: close consumer port 4 with a blanking plug
3
Note The term “conversion” includes even very simple measures, for example closing consumer port 2 or 4 with a blanking plug.
© Festo Didactic GmbH & Co. KG 541090
35
Exercise 4: Packing plastic pellets
Selecting solenoid valves A valve is selected on the basis of the following criteria: • Task • Required performance in the event of a power failure • Lowest possible overall costs The following valves are available for actuating a single-acting cylinder. • A pilot actuated 3/2-way solenoid valve with spring return and manual override • A pilot actuated 5/2-way solenoid valve with spring return and manual override –
Select a valve and justify your decision.
Valve type
Reason
Pilot actuated 5/2-way
5/2-way solenoid valves can be used in a broad range of applications. In practice, this means that only
solenoid valve with spring return and manual override
one valve type is required for a variety of requirements or applications. This, in turn, results in considerable cost reductions as larger quantities lead to more favourable valve procurement and stocking of spare parts. Compared with maintenance for a single valve type, servicing a variety of valves is considerably more expensive. 3/2-way valves can only be used to actuate single-acting cylinders, but 5/2-way valves can be used with single as well as double-acting cylinders. That is why the 5/2-way valve is the right choice. The fact that a 3/2-way valve is usually about 5% less expensive than a 5/2-way valve is not decisive due to the above mentioned advantages of the 5/2-way valve.
Note In addition to the costs mentioned above, the overall costs of a valve also include expenses for installation and maintenance, as well as warehousing costs for replacement parts.
36
© Festo Didactic GmbH & Co. KG 541090
Exercise 4: Packing plastic pellets
Logic operations – the OR function It should be possible to make the piston rod of a cylinder advance using two pushbuttons, namely S1 and S2. When at least one of the two pushbuttons is activated solenoid coil 1M1 is energised, solenoid valve 1V1 switches to the actuated position and the piston rod advances. When both pushbuttons are released, the valve is switched to its normal position and the piston rod is retracted. –
Create the associated functions table and the logic symbol. S1
S2
1M1
1V1
0
0 (not actuated)
0 (not actuated)
0 (not actuated)
0 (not actuated)
1 (actuated)
1 (actuated)
1 (actuated)
1 (actuated)
0 (not actuated)
1 (actuated)
1 (actuated)
1 (actuated)
1 (actuated)
1 (actuated)
1 (actuated)
Functions table
S1
1 1M1
S2
Logic symbol
Note 0 means that the pushbutton is not activated and the piston does not advance. 1 means that the pushbutton is activated and the piston advances.
© Festo Didactic GmbH & Co. KG 541090
37
Exercise 4: Packing plastic pellets
Complete the pneumatic and electrical circuit diagrams –
Complete the pneumatic and electrical circuit diagrams. +24 V
1
2
13 S1
3
13
14
12
14
K1
S2 14
11
A1 K1
1M1 A2
0V
Pneumatic circuit diagram
38
11
12 14 .3
21
22 24
31
32 34
41
42 44
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 541090
Exercise 4: Packing plastic pellets
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its normal position, cylinder 1A1 is in the advanced end position and the rear chamber is filled with compressed air.
Step 1-2 By activating pushbutton S1 or S2 (both laid out as NO contacts) relay K1 is energised, change-over contact K1 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way valve 1V1 is energised. Valve 1V1 is reversed. The rear chamber of cylinder 1A1 is exhausted and the spring forces the cylinder into its retracted end position.
Step 2-3 As soon as pushbutton S1 or S2 (both laid out as NO contacts) is no longer activated, relay K1 is deenergised and change-over contact K1(connected as an NO contact) is opened. Coil 1M1 is de-energised as a result and valve 1V1 is returned to its initial position by the reset spring. The rear chamber of cylinder 1A1 is filled with compressed air; the cylinder returns to the advanced end position.
© Festo Didactic GmbH & Co. KG 541090
39
Exercise 4: Packing plastic pellets
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, single-acting
1
One-way flow control valve
1
5/2-way solenoid valve
2
Pushbutton (normally open)
1
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
40
© Festo Didactic GmbH & Co. KG 541090
Exercise 5: Diverting packages Learning objectives After completing this exercise: • You’ll be familiar with the set-up and mode of operation of a double-acting cylinder. • You’ll be familiar with the set-up and mode of operation of a double solenoid valve.
Presentation of the problem Packages will be diverted from one conveyor belt to another by means of a diverting device.
Layout
Diverting device
© Festo Didactic GmbH & Co. KG 541090
41
Exercise 5: Diverting packages
• •
1 2 3 4 5 6
1 2
42
Parameters A double-acting cylinder will be used. The cylinder will be controlled indirectly and using a pushbutton. In the event of a power failure, the cylinder’s piston rod should remain in its current end position.
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
Control sequence The diverting device is advanced when one of the pushbuttons is activated. The package is transferred and transported further. The diverting device is returned to its initial position when another pushbutton is activated.
© Festo Didactic GmbH & Co. KG 541090
Exercise 5: Diverting packages
Using solenoid valves Two factors need to be taken into consideration when deciding which type of valve will be used for a specific application. • Duration or timeframe • Number or frequency of required switching operations In order to make the best possible use of a directional control valve, it must be decided on a case-by-case basis which is more economical for the respective application: • A double solenoid valve or • A directional control valve with spring return –
Decide whether a double solenoid valve or a solenoid valve with spring return is more economical for each of the applications listed below and give reasons for your decision.
Application 1 The clamping cylinder in a milling station must clamp a workpiece for the duration of the milling process (approx. 10 minutes with 60 clamping operations per day). Valve type
Reason
Double solenoid valve
The signal must be stored for switching operations of long duration. In the case of double solenoid valves, this is accomplished by means of static friction and in the case of directional control valves with spring return by continuously energising the solenoid coil. Clamped workpieces must not be released in the event of an emergency stop, which is why solenoid valves with spring return must not be used for this application.
Application 2 The ejecting cylinder in a sorting system needs to push defective workpieces off a conveyor belt (duration of approx. 1 second, 600 push-out operations per day). Valve type
Reason
Solenoid valve with spring return
The signal need not be stored for switching operations of short duration. Solenoid valves with spring return have the following advantage: only one solenoid coil needs to be actuated, i.e. energised, in order to switch the valve.
© Festo Didactic GmbH & Co. KG 541090
43
Exercise 5: Diverting packages
Mode of operation of a solenoid valve 4
2
5
3
1M1
–
1M2 1
Describe the mode of operation of the directional control valve shown above. Pilot actuated 5/2-way double solenoid valve with manual override When the piston is at the left-hand limit stop, ports 1 (supply port) and 2 (consumer port), as well as ports 4 (consumer port) and 5 (exhaust port), are connected. If the left-hand solenoid coil is energised, the piston moves to the right-hand limit stop and ports 1 and 4, as well as ports 2 and 3 (exhaust port) are connected (pilot line, 14 and 12, function when actuated: supply port 1 and consumer port 4 or 2 are connected). If the valve needs to be switched back to its initial position, it’s not enough to simply interrupt electrical power to the left-hand solenoid coil. In fact, the right-hand solenoid coil must also be energised. If neither of the solenoids is actuated, the piston remains in its last position (signal control in the power section) due to friction. This is also the case when both solenoids are energised at the same time, because they work against each other with identical force. In the de-energised state, the valve can be switched via the manual override.
44
© Festo Didactic GmbH & Co. KG 541090
Exercise 5: Diverting packages
Calculating the current consumption of a solenoid coil A solenoid valve with spring return needs to be switched with pushbutton S1. –
Calculate current and power consumption for solenoid coil 1M1 based on a 24 V DC power supply and a coil resistance of 48 Ω (Ohm).
+24 V
1
13 S1 14
1M1
0V
Current consumption at 1M1 In accordance with Ohm’s law, U = R • I, current consumption of 0.5 A (ampere) is calculated as follows: I=
U 24V = = 0,5A R 48Ω
Power consumption at 1M1 Power consumption of 12 W (watt) is calculated as follows: P = U • I = 24 V • 0.5 A = 12 W
© Festo Didactic GmbH & Co. KG 541090
45
Exercise 5: Diverting packages
Calculating the current consumption of a solenoid coil –
If the solenoid coil in question were connected to 24 V AC, would power consumption at 1M1 be higher or lower? Give reasons for your answer.
Equal
Higher
Lower
Reason The magnetic fields caused by alternating current generate an induction voltage in the coil’s windings which counteracts the applied voltage and increases coil X
resistance. This resistance in the AC coil (impedance) is made up of Ohmic resistance and so-called inductive reactance. As a result, effective current is reduced.
46
© Festo Didactic GmbH & Co. KG 541090
Exercise 5: Diverting packages
Complete the circuit diagrams –
Complete the pneumatic circuit diagram for the diverting device.
Pneumatic circuit diagram
–
Complete the electrical circuit diagram for the diverting device.
+24 V
1
3
2
13 S1
13
12
14
K2 11
14
A1
11
A1 1M1
K2 A2
0V
14
K1
S2 14
K1
12
4
1M2
A2
11
12 14 .3
11
12 14 .4
21
22 24
21
22 24
31
32 34
31
32 34
41
42 44
41
42 44
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 541090
47
Exercise 5: Diverting packages
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its initial position, cylinder 1A1 is in the retracted end position.
Step 1-2 After activating pushbutton S1 (NO contact) relay K1 is energised, change-over contact K1 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way double pilot valve 1V1 is energised. Valve 1V1 is reversed. The rear chamber of cylinder 1A1 is now filled with compressed air and the front chamber is exhausted. Cylinder 1A1 advances. As soon as pushbutton S1 (NO contact) is no longer activated, relay K1 is de-energised and change-over contact K1 (connected as an NO contact) is opened. As a result, coil 1M1 is also de-energised.
Step 2-3 After activating pushbutton S2 (NO contact) relay K2 is energised and change-over contact K2 (connected as an NO contact) is closed. Coil 1M2 is energised as a result and valve 1V1 is switched back to its initial position. The front chamber of cylinder 1A1 is filled with compressed air and the rear chamber is exhausted. Cylinder 1A1 returns to its retracted end position. As soon as pushbutton S2 (NO contact) is no longer activated, relay K2 is de-energised and change-over contact K2 (connected as an NO contact) is opened. As a result, coil 1M2 is also de-energised.
48
© Festo Didactic GmbH & Co. KG 541090
Exercise 5: Diverting packages
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way double solenoid valve
2
Pushbutton (normally open)
2
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
© Festo Didactic GmbH & Co. KG 541090
49
Exercise 5: Diverting packages
50
© Festo Didactic GmbH & Co. KG 541090
Exercise 6: Pushing wooden boards out of a stacking magazine Learning objectives After completing this exercise: • You’ll be able to make use of double-acting cylinders. • You’ll be familiar with the set-up and mode of operation of a double solenoid valve. • You’ll be familiar with one option for end-position sensing in cylinders.
Presentation of the problem Wooden boards need to be pushed out of a stacking magazine and into a mounting device.
Layout
Stacking magazine
© Festo Didactic GmbH & Co. KG 541090
51
Exercise 6: Pushing wooden boards out of a stacking magazine
52
•
Parameters The cylinder’s advanced end position needs to be sensed.
1 2 3 4 5
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Create an equipment list. Set up the control system, both pneumatically and electrically. Double check the control sequence.
1 2
Control sequence A wooden board is pushed out of the stacking magazine with a slide after pressing a pushbutton. After reaching the advanced end position, the slide is returned to its initial position.
© Festo Didactic GmbH & Co. KG 541090
Exercise 6: Pushing wooden boards out of a stacking magazine
Components included in an electro-pneumatic system The components included in an electro-pneumatic system are represented in the pneumatic and/or the electrical circuit diagram. –
Tick off the type of diagram in which the following components need to be represented.
Component
Pneumatic circuit diagram
Manually operated pushbutton
Electrical circuit diagram X
Cylinder
X
Valve
X
Solenoid coil
X
Relay
X X
Electromechanical limit switch
X
X
Electronic proximity switch
X
X
Indicator
© Festo Didactic GmbH & Co. KG 541090
X
53
Exercise 6: Pushing wooden boards out of a stacking magazine
Components included in an electro-pneumatic system The purpose of sensors in electro-pneumatic control systems is to acquire information and forward it to signal processing. –
Which function(s) can an electromechanical limit switch in an electro-pneumatic control system carry out? Sensing piston rod end positions in cylinder drive units Detecting the presence or the position of a workpiece
54
© Festo Didactic GmbH & Co. KG 541090
Exercise 6: Pushing wooden boards out of a stacking magazine
Representation of limit switches Limit switches can be actuated in different ways. They function as NC, NO or change-over contacts and can be actuated or unactuated when the system is in its neutral position. –
Describe the design and function of the symbols shown below. Enter the descriptions to the table.
Description: design/function Roller actuated limit switch with NC function, unactuated
Symbol
1
2 Roller actuated limit switch with NO function, unactuated
3
4
© Festo Didactic GmbH & Co. KG 541090
55
Exercise 6: Pushing wooden boards out of a stacking magazine
Creating a switching elements table One way of recording the contacts controlled by a relay is to list them in a switching elements table. –
Create switching elements tables for relays K6 and K9. 10
+24 V
11
14
...
12
12
K5
14
K6 11
12 12
14
13 12
K2 11
14
K7 11
14 12
14
K4 11
15 12
14
K8 11
16 12
14
K3 11
17 14
12 K9
11
18
19
34
32
34
32
K6
K7
11
31
31
14
12 K1
11
24
22 K9
22
24
K6 21
24
K8
32
34
K9 21
A1 K8
A2
22
21
A1 K7
A2
24
K7 21
A1 K6
22
32
34
K8 31
31
A1 K9
A2
1M1
2M1
A2
0V
...
Electrical circuit diagram
Switching element K6
Description Relay K6 actuates the following switching elements: 1 NO contact in current path 11 1 NO contact in current path 12 1 NO contact in current path 18
K9
Relay K6 actuates the following switching elements: 1 NO contact in current path 17
10 18
17
1 NC contact in current path 10 1 NC contact in current path 18
Switching elements table
56
© Festo Didactic GmbH & Co. KG 541090
Exercise 6: Pushing wooden boards out of a stacking magazine
Creating a switching elements table Another way of recording the contact sets controlled by a relay is shown in the following circuit diagram. +24 V
1
2
4
3
6
5
8
7
11
10
9
21
12
25
14
K11
NA NOT-AUS 22
1B2
2B1
13
2B2 S1 Start
32
K11 11
1B1
27 24
22
12
13
14 12
12 K5
16
14 12
14 12
11
11
K6 11
14
14 12
K7
17
14 12
K4 11
18
14 12
K8 11
19
14 12
K3 11
14 22
K9 11
20
21
24 12
K1 11
14 32
K10 21
22 34
23 34
32
K6
34
32
K7
11
21
24
31
26 34 22
32
K8
31
K9
31
34
K11
24
K3
31
31
21
14
12 K1
11
24
22 K10
A1 K11
A1 K1
K2
A2 0V
A1
A1 K3
A2
A1 K4
A2
A1 K5
A2
24
22
K7
K8
24
22 K9
21
21
21
21
A1
A1
A1
A1
A1
K8
A2
K9
A2
44
42 K7
21
K7
A2
24
22
K6
K6
A2
24
22
44
42 K8
K9
41 1M1
44
42
K10
41 2M1
34
32
41 2M2
31 1M2
K10
A2
A2
A2
11
12 14 .11
11
12 14 .12
11
12 14 .14
11
12 14 .18
11
12 14 .16 11
12 14 .12
11
12 14 .13
11
12 14 .15
11
12 14 .17
11
12 14 .19
11
12 14 .21
21
22 24 .25
21
22 24 .20
21
22 24
21
22 24 .27
21
22 24
21
22 24
21
22 24 .14
21
22 24 .16
21
22 24 .18
21
22 24 .20
21
22 24 .12
31
32 34 .27
31
32 34
31
32 34
31
32 34
31
32 34
31
32 34
31
32 34 .22
31
32 34 .23
31
32 34 .24
31
32 34 .26
31
32 34 .26
41
42 44
41
42 44
41
42 44
41
42 44
41
42 44
41
42 44
41
42 44
41
42 44 .22
41
42 44 .23
41
42 44 .24
41
42 44
1A1+
2A1+
2A1-
1A1-
Electrical circuit diagram
–
Complete the entries for the relays listed in the table beneath. Designate the current path within which the respective contact is used, as well as the function fulfilled by the set of contacts (normally open or normally closed).
Relay
Current path
Function: NO
Function: NC
Relay K9
Current path 19
X
Current path 20
X X
Current path 24 Current path 26 Relay K10
X X
Current path 12 Current path 21 Current path 26
© Festo Didactic GmbH & Co. KG 541090
X X
57
Exercise 6: Pushing wooden boards out of a stacking magazine
Complete the circuit diagrams –
Complete the pneumatic circuit by adding the valve actuation and designating it. 1A1
1V2
1V1
1B2
1
1
2
2
4
2
5
3
1M1
1V3
1M2 1
Pneumatic circuit diagram
–
Complete the electrical circuit diagram.
+24 V
1
3
2
13 S1
4
2
14
12
14
K2 11
A1 1M1
K2 A2
0V
14 11
1
A1 K1
12 K1
1B2
4
1M2
A2
11
12 14 .3
11
12 14 .4
21
22 24
21
22 24
31
32 34
31
32 34
41
42 44
41
42 44
Electrical circuit diagram
58
© Festo Didactic GmbH & Co. KG 541090
Exercise 6: Pushing wooden boards out of a stacking magazine
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its normal position, cylinder 1A1 is in the retracted end position
Step 1-2 By activating pushbutton S1 (NO contact) relay K1 is energised, change-over contact K1 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way solenoid valve 1V1 is energised. Valve 1V1 is reversed. The rear chamber of cylinder 1A1 is now filled with compressed air and the front chamber is exhausted. Cylinder 1A1 advances. When pushbutton S1 (NO contact) is no longer activated, relay K1 is de-energised and change-over contact K1 (connected as an NO contact) is opened. As a result, coil 1M1 is also de-energised.
Step 2-3 When the cylinder reaches its advanced end position, the piston rod actuates electrical limit switch 1B2. Change-over contact 1B2 (connected as an NO contact) is closed and relay K2 is energised. Change-over contact K2 (connected as an NO contact) is closed and solenoid coil 1M2 is energised. Valve 1V1 is returned to its normal position. The front chamber of cylinder 1A1 is filled with compressed air and the rear chamber is exhausted. The cylinder returns to the retracted end position. As soon as electrical limit switch 1B2 (change-over contact, connected as an NO contact) is no longer actuated, relay K2 is de-energised and change-over contact K2 (connected as an NO contact) is opened. As a result, coil 1M2 is also de-energised.
© Festo Didactic GmbH & Co. KG 541090
59
Exercise 6: Pushing wooden boards out of a stacking magazine
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way solenoid valve
1
Pushbutton (normally open)
1
Limit switch (normally open)
2
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
60
© Festo Didactic GmbH & Co. KG 541090
Exercise 7: Sorting packages Learning objectives After completing this exercise: • You’ll be able to calculate piston forces based on specified values. • You’ll be able to calculate characteristic electrical values. • You’ll be able to make use of indirect actuation. • You’ll be familiar with the logic AND operation and be able to set it up.
Presentation of the problem Packages are directed past workstations on a roller conveyor. The packages can be diverted by means of deflectors at specific points.
Layout
Conveyor for packages
© Festo Didactic GmbH & Co. KG 541090
61
Exercise 7: Sorting packages
62
• • •
Parameters A double-acting cylinder will be used. The cylinder will be controlled indirectly using pushbuttons and electromechanical limit switches. The cylinder can only advance when the piston rod is in the retracted end position.
1 2 3 4 5
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Create an equipment list. Set up the control system, both pneumatically and electrically. Double check the control sequence.
1 2
Control sequence The cylinder’s piston rod should advance automatically as soon as pushbutton S1 is activated. When the pushbutton is no longer activated, the piston rod must return to the retracted end position.
© Festo Didactic GmbH & Co. KG 541090
Exercise 7: Sorting packages
Calculating piston force The piston of a double-acting cylinder has a diameter of 20 mm and the piston rod has a diameter of 8 mm. Friction loss in the cylinder amounts to 10%. –
Calculate the effective piston force for both the forward and the return stroke at an operating pressure of 6 bar (600 kPa).
Calculate for:
Solution
Forward stroke
F = 188 N
Return stroke
F = 158 N
© Festo Didactic GmbH & Co. KG 541090
63
Exercise 7: Sorting packages
Calculating characteristic electrical values The coil in a relay has a power rating of 1 W. Measurement of resistance between terminals A1 and A2 resulted in a value of 580 Ω. –
Calculate the relay’s operating voltage. The following applies to electrical power: U2 P = U•I or P= R As power and resistance are known: U2 P= U2 = P • R R
U2 = 1 • 580
or
P = I2 • R
U2 = 580
U=
580
U = 24.083189157584590960256482060757 Umax ~ 24 V
64
© Festo Didactic GmbH & Co. KG 541090
Exercise 7: Sorting packages
Basic principles It should be possible to make the piston rod of a cylinder to advance using two pushbuttons, namely S1 and S2. When both pushbuttons are activated simultaneously, solenoid coil 1M1 is energised, solenoid valve 1V1 switches to the actuated position and the piston rod advances. When one of the two pushbuttons is released, the valve is switched to its normal position and the piston rod is retracted. –
Create the associated functions table and draw the logic symbol. Note 0 means that the pushbutton is not activated and the piston does not advance. 1 means that the pushbutton is activated and the piston advances.
S1
S2
1M1
1V1
0 (not actuated)
0 (not actuated)
0 (not actuated)
0 (not actuated)
0 (not actuated)
1 (actuated)
0 (not actuated)
0 (not actuated)
1 (actuated)
0 (not actuated)
0 (not actuated)
0 (not actuated)
1 (actuated)
1 (actuated)
1 (actuated)
1 (actuated)
Functions table
S1
&
1M1
S2
Logic symbol
© Festo Didactic GmbH & Co. KG 541090
65
Exercise 7: Sorting packages
Complete the circuit diagrams –
Set up the pneumatic control system in accordance with the circuit diagram.
Pneumatic circuit diagram
–
Complete the electrical circuit diagram.
+24 V
1
2
13 S1
3
4
2
4
2 1 B2
1B1 14
12
14
K1 1
1
5
4
12 K3
11 12
14 11
14
K2 11 A1 K1
A1 K2
K3
A2 0V
1M1
1M2
A2
11
12 14 .4
11
12 14 .4
11
12 14 .5
21
22 24
21
22 24
21
22 24
31
32 34
31
32 34
31
32 34
41
42 44
41
42 44
41
42 44
Electrical circuit diagram
66
© Festo Didactic GmbH & Co. KG 541090
Exercise 7: Sorting packages
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its initial position, cylinder 1A1 is in the retracted end position. When cylinder 1A1 is in its retracted end position, electrical limit switch 1B1 is actuated (change-over contact, connected as an NO contact), change-over contact 1B1 is closed and relay K2 is energised.
Step 1-2 After activating pushbutton S1 (NO contact) relay K1 is energised, change-over contact K1 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way solenoid valve 1V1 is energised. Double solenoid valve 1V1 is reversed. The piston end of cylinder 1A1 is filled with compressed air while the piston rod end is exhausted. Cylinder 1A1 advances. As soon as cylinder 1A1 leaves its retracted end position, limit switch 1B1is no longer actuated and change-over contact 1B1 is opened. NO contact K2 is opened as a result and solenoid coil 1M1 is no longer energised. The double solenoid valve remains in the right-hand switching position.
Step 2-3 When the cylinder reaches its advanced end position, the piston rod actuates electrical limit switch 1B2 (change-over contact, connected as an NO contact). Change-over contact 1B2 is closed. Relay K3 is energised. Due to the fact that change-over contact K3 is closed (connected as an NO contact), solenoid coil 1M2 is also energised. Valve 1V1 is reversed. The piston rod end of cylinder 1A1 is pressurised with compressed air while the piston end is exhausted. The cylinder returns to the retracted end position. As soon as electrical limit switch 1B2 (change-over contact, connected as an NO contact) is no longer actuated, relay K3 is de-energised and change-over contact K3 (connected as an NO contact) is opened. As a result, coil 1M2 is also de-energised. The cylinder remains in the retracted end position.
© Festo Didactic GmbH & Co. KG 541090
67
Exercise 7: Sorting packages
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way solenoid valve
1
Pushbutton (normally open)
2
Limit switch (normally open)
3
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
68
© Festo Didactic GmbH & Co. KG 541090
Exercise 8: Sanding wooden boards Learning objectives After completing this exercise: • You’ll be familiar with logic operations and be able to set them up. • You’ll be able to explain and set up an electrical latching circuit with dominant breaking signal.
Presentation of the problem Wooden boards are put onto a sliding platform manually. The boards are pushed under a belt sander by a pneumatic drive.
Layout
Sliding platform
© Festo Didactic GmbH & Co. KG 541090
69
Exercise 8: Sanding wooden boards
70
• •
Parameters A double-acting cylinder will be used. The cylinder will be actuated indirectly.
1 2 3 4 5 6
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
1 2
Control sequence The piston rod of a cylinder must advance when pushbutton S1 is activated. The piston rod is retracted when pushbutton S2 is activated.
© Festo Didactic GmbH & Co. KG 541090
Exercise 8: Sanding wooden boards
Signal storage If the piston rod of a cylinder also needs to be advanced when the pushbutton is pressed only briefly, activation of the pushbutton must be stored. The signal can be stored either in the power section or in the signal control section of the circuit. –
Described how signal storage is implemented in the power section or the signal control section.
Signal storage location
Description: signal storage
Signal storage in the power section
A double solenoid valve is used for storage. As a result of the piston’s static friction, the double solenoid valve is retained in is position, even when the respective solenoid coil is no longer energised.
Signal storage in the signal control section
By means of a solenoid valve with spring return and a relay with self-latching loop The relay coil is energised and a contact closes. When the on pushbutton is released, current continues to flow through the coil via the closed contact, the relay is retained in the activated position and thus the solenoid valve with spring return remains in the actuated position. The electrical circuit is interrupted when an off pushbutton is activated. Depending on how the two pushbuttons are arranged, we differentiate between dominantly setting and dominantly resetting self-latching loops.
© Festo Didactic GmbH & Co. KG 541090
71
Exercise 8: Sanding wooden boards
Analysing circuits –
Describe the performance of the specified circuit (piloted 5/2-way solenoid valve with spring return, double-acting cylinder) in the event of a power failure and pressure failure.
Electrical power supply failure
Pressure failure
The solenoid valve with spring return is switched to its normal
The solenoid valve returns to its normal position due to a lack of
position and the double-acting cylinder returns to the retracted
adequate operating pressure.
end position. The solenoid valve and thus the cylinder as well, can be switched by means of manual override.
72
The double-acting cylinder is unpressurised and assumes an undefined position.
© Festo Didactic GmbH & Co. KG 541090
Exercise 8: Sanding wooden boards
Logic operations Lamp P1 should always light up when pushbutton S1 is not activated. –
Create the associated functions table and the logic symbol.
S1
P1
0 (not actuated)
1 (actuated)
1 (actuated)
0 (not actuated)
Functions table
S2
1
P1
Logic symbol
Note 0 means pushbutton S1 not activated or lamp 1 off. 1 means pushbutton S1 activated or lamp 1 on.
© Festo Didactic GmbH & Co. KG 541090
73
Exercise 8: Sanding wooden boards
Complete the circuit diagrams –
Complete the pneumatic circuit diagram for the sliding table.
Pneumatic circuit diagram
–
Complete the electrical circuit diagram for the sliding table.
Electrical circuit diagram
74
© Festo Didactic GmbH & Co. KG 541090
Exercise 8: Sanding wooden boards
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its initial position, cylinder 1A1 is in the retracted end position.
Step 1-2 When pushbutton S1 (NO contact) is activated, relay K1 is energised and change-over contact K1 (connected as an NO contact) in current path 2 closes and activates the self-latching loop in relay K1. Furthermore, change-over contact K1 in current path 3 closes and solenoid coil 1M1 at 5/2-way solenoid 1V1 is energised. Valve 1V1 is reversed. The piston end of cylinder 1A1 is now filled with compressed air and the piston rod end is exhausted. Cylinder 1A1 advances.
Step 2-3 When pushbutton S2 (NC contact) is activated, self-latching at relay K1 is terminated. Change-over contact K1 (connected as an NO contact) in current path 3 opens and relay K1 is de-energised. Valve 1V1 is reset by the reset spring. The piston rod end of cylinder 1A1 is filled with compressed air while the piston end is exhausted. The cylinder returns to the retracted end position.
© Festo Didactic GmbH & Co. KG 541090
75
Exercise 8: Sanding wooden boards
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
5/2-way solenoid valve
1
Pushbutton (normally open)
1
Pushbutton (normally closed)
1
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
76
© Festo Didactic GmbH & Co. KG 541090
Exercise 9: Diverting bottles Learning objectives After completing this exercise: • You’ll be familiar with various types of end-position control and learn to select the appropriate type. • You’ll be familiar with latching circuits with varying performance features.
Presentation of the problem Bottles need to be diverted from a conveyor belt with a diverting device to another conveyor belt in a linearly indexed fashion. Once switched on, the system should run continuously. It should not be switched off until a stop signal is generated.
Layout
Diverting device for bottles
© Festo Didactic GmbH & Co. KG 541090
77
Exercise 9: Diverting bottles
•
Parameters The latching circuit used should demonstrate dominant off characteristics.
1 2 3 4 5 6
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
1 2 3
78
Control sequence The sequence is started by pressing a pushbutton. If 3 bottles are present, the diverting cylinder’s piston rod is advanced. The bottles are diverted and transported to a second conveyor belt. The sequence is stopped by pressing a second pushbutton.
© Festo Didactic GmbH & Co. KG 541090
Exercise 9: Diverting bottles
Latching circuits A relay circuit with self-latching loop is required in order to store a signal in the signal control section. The relay coil is energised when pushbutton S1 is activated. +24 V
1
2
13 S1
12
14
K1 14
11
A1 K1 A2 0V
–
11
12 14 .2
21
22 24
31
32 34
41
42 44
Complete the electrical circuit diagram so that the relay is self-latched after releasing pushbutton S1 and describe the circuit’s function. When pushbutton S1 is activated, coil K1 is energised and activates the change-over contact. Current path 2 is closed as a result, the coil remains energised and the change-over contact is retained in its current switching position. The circuit is self-latching as long as power supply is available.
© Festo Didactic GmbH & Co. KG 541090
79
Exercise 9: Diverting bottles
Latching circuits In order to terminate self-latching, the power supply to the coil must be interrupted. A separate NC contact is required to this end. Depending on how this NC contact is arranged, we differentiate between two types of self-latching. • Dominantly setting self-latching • Dominantly resetting self-latching –
Complete the following electrical circuit diagram so that self-latching is reliably terminated when pushbutton S2 is activated.
+24 V
2
1
13 S1
12
+24 V
13
14
K1 14
2
1
S1
12
14
K1 14
11
11
31
31
S2
S2 32
32
A1
A1
K1
K1 A2
0V 11
12 14 .2
21
A2 0V 11
12 14 .2
22 24
21
22 24
31
32 34
31
32 34
41
42 44
41
42 44
Electrical circuit diagram, left: dominantly resetting self-latching, right: dominantly setting self-latching
80
© Festo Didactic GmbH & Co. KG 541090
Exercise 9: Diverting bottles
Latching circuits Different signal storing circuits have different characteristics: • For simultaneous occurrence of setting and resetting conditions • In the event of failure of electrical control energy or broken wire –
Complete the table by indicating how each respective valve responds. Signal storage via an electrical latching circuit combined with Signal storage via a double spring return valve solenoid valve Dominantly setting Dominantly resetting
Simultaneous setting and resetting signal Electrical power supply failure
Valve position remains unchanged.
The valve is actuated.
The valve returns to its normal position.
Valve position remains
The valve returns to its normal
The valve returns to its normal
unchanged.
position.
position.
© Festo Didactic GmbH & Co. KG 541090
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Exercise 9: Diverting bottles
Limit switches and proximity switches The purpose of limit switches and proximity switches is to acquire information and forward it to signal processing. They include: • Mechanical position switches (limit switches) • Magnetic proximity switches • Inductive proximity switches • Optical proximity switches • Capacitive proximity switches –
Match the terms with the corresponding circuit symbols in the table.
Circuit symbol
Designation
BN
Magnetic proximity switch BK
BU BN
Optical proximity switch BK
BU
Inductive proximity switch
BN BK
BU
Mechanical position switch (limit switch)
4
2
1
BN
Capacitive proximity switch BK
BU
82
© Festo Didactic GmbH & Co. KG 541090
Exercise 9: Diverting bottles
Complete the circuit diagrams – –
Complete the pneumatic circuit. Complete the electrical circuit diagram. 1B1
1V2
1V1
1A1
1B2
1
1
2
2
4
2
5
3
1V3
1M1
1M2 1
Pneumatic circuit diagram
+24 V
1
2
13 S1
12
14
3
1B1
BN
11
1B2
7
6
BN
BK
K1 14
5
4
12
BK
BU
14
K2
8
12
11
BU
22
31
14
K3 11
24
K1 21
S2 32
A1 K1
A1 K2
A2 0V 11
12 14 .2
21
22 24 .7
31
32 34
41
42 44
A1 K3
1M1
A2
11
12 14 .7
1M2
A2
11
12 14
21
22 24
21
22 24
31
32 34
31
32 34
41
42 44
41
42 44
.8
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 541090
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Exercise 9: Diverting bottles
Sequence description –
Describe the control system’s operating sequence. Initial position In its initial position, cylinder 1A1 is in the retracted end position. When cylinder 1A1 is in its retracted end position, magnetic proximity switch 1B1 is actuated (NO contact), relay K2 is energised and change-over contact K2 (connected as an NO contact) in current path 7 closes.
Step 1-2 When pushbutton S1 (NO contact) is activated, relay K1 is energised and change-over contact K1 (connected as an NO contact) in current path 2 closes and activates the self-latching loop in relay K1. Furthermore, change-over contact K1 (connected as an NO contact) in current path 7 closes and solenoid coil 1M1 at 5/2-way double solenoid valve 1V1 is energised. Double solenoid valve 1V1 is reversed. The rear chamber of cylinder 1A1 is now filled with compressed air and the front chamber is exhausted. Cylinder 1A1 advances. As soon as cylinder 1A1 leaves its retracted end position, proximity switch 1B1 is no longer actuated (NO contact). Change-over contact K2 (connected as an NO contact) in current path 7 is opened as a result and solenoid coil 1M1 is no longer energised. The double solenoid valve nevertheless remains in the right-hand switching position.
Step 2-n When the cylinder reaches the advanced end position, magnetic proximity switch 1B2 is activated (NO contact) and relay K3 is energised. Change-over contact K3 (connected as an NO contact) in current path 8 is closed and solenoid coil 1M2 is energised. As a result, valve 1V1 is returned to its normal position and cylinder 1A1 is returned to its retracted end position. As soon as proximity switch 1B2 (NO contact) is no longer activated, relay K3 is de-energised and change-over contact K3 (connected as an NO contact) in current path 8 is opened. As a result, coil 1M2 is also de-energised. As the electrical latching circuit at relay K1 is still active, solenoid coil 1M1 once again receives a switching signal when the retracted end position is reached, so that cylinder 1A1 advances again immediately.
Step n-(n+1) Oscillating motion of cylinder 1A1 can be interrupted by activating pushbutton S2 (NC contact). Selflatching at relay K1 is terminated as a result. The cylinder returns to the retracted end position and remains there.
84
© Festo Didactic GmbH & Co. KG 541090
Exercise 9: Diverting bottles
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components and their quantities in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
1
Double solenoid valve, 5/2-way
1
Pushbutton (normally open)
1
Pushbutton (normally closed)
3
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
© Festo Didactic GmbH & Co. KG 541090
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Exercise 9: Diverting bottles
86
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys Learning objectives After completing this exercise: • You’ll be able to set up pressure-dependent reversing. • You’ll be familiar with the set-up and mode of operation of magnetic proximity switches.
Presentation of the problem Taper keys are required for the production of door frames. The keys will be stamped with a stamping system.
Layout
Stamping system
© Festo Didactic GmbH & Co. KG 541090
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Exercise 10: Stamping taper keys
88
•
Parameters Stamping pressure should be 5.5 bar (550 kPa).
1 2 3 4 5
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the pneumatic and electrical circuit diagrams. Create an equipment list. Set up the control system, both pneumatically and electrically. Double check the control sequence.
1 2
Sequence description The stamping tool is advanced after pressing a pushbutton and a taper key is stamped. After stamping pressure is reached, the stamping tool is advanced to its starting position.
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys
Magnetic proximity switches As opposed to limit switches, proximity switches are contact-free and require no external actuating force. –
Describe the set-up and function of a magnetic proximity switch (reed switch).
Description: design and function
Circuit symbol
Schematic drawing
Reed switches are magnetically actuated proximity switches. They consist of two contact reeds which are located in a glass tube which is filled with inert gas. When a magnetic force is applied, the two reeds make contact enabling electrical current to flow. In the case of reed switches, which function as NC contacts, the contact blades are preloaded with small magnets. This
BN
preloading is overpowered by the significantly stronger switching magnet. Reed switches have a long service life and minimal switching times (approx. 0.2 ms).
BK BU
They’re maintenance free, but they should not be used in the presence of strong magnetic fields (e.g. close to resistance welding units).
© Festo Didactic GmbH & Co. KG 541090
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Exercise 10: Stamping taper keys
Magnetic proximity switches As regards the polarity of the output signal, there are two different types of electronic proximity switches: PNP and NPN. –
Explain the difference between these two different designs.
PNP
NPN
In the case of negative switching proximity switches, power
In the case of positive switching proximity switches, zero voltage
supply is present at the output when there are no parts within the is present at the output when there are no parts within the switch’s response range. When a workpiece or machine component approaches the switch, the output is switched to 0 V.
24 V
switch’s response range. When a workpiece or machine component approaches the switch, the output is switched and power supply is present.
24 V
B
1
B
1
4 3
90
4 3
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys
Pressure switches Pressure-sensitive sensors, so-called pressure switches, are used in order to measure and monitor pressure within the system. –
Describe the mode of operation of a pressure switch. A pneumatic pressure signal switches an electrical signal generator (usually laid out as a change-over contact) in the pressure switch, i.e. a pneumatic input signal is read out as an electrical signal. Pressure switches are available with fixed, as well as adjustable switching pressures.
© Festo Didactic GmbH & Co. KG 541090
91
Exercise 10: Stamping taper keys
Pressure switches Pressure sensors can be subdivided into two groups. Differentiation is made between: • Pressure sensors with mechanical contact (mechanical mode of operation) • Pressure sensors with electronic switching (electronic mode of operation) –
Describe the task and function of the pressure switch depicted below.
Description: task and function
Circuit symbol
Pressure switches are used in order to
Electrical
generate an electrical output signal when a specified pressure is reached.
1 p
In the case of this mechanical pressure
Schematic drawing
4 2
U
1 4
3
switch, pressure acts on the surface of a piston. If the force generated by prevailing
2
pressure exceeds the force of the spring used, the piston moves and actuates the
Pneumatic
X
change-over contact points. Switching pressure can be adjusted by preloading the spring, which is why this pressure sensor is called a pressure switch.
92
p
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys
Selecting proximity switches The end positions of a cylinder drive are to be sensed with proximity switches. The proximity switches must fulfil the following requirements: • The piston rod’s end positions must be sensed in a contactless fashion. • The proximity switches must be insensitive to dust. • The cylinder’s piston rod and trip cam are made of metal. –
Make your selection and indicate which proximity switches fulfil the specified requirements. Enter your selection in the table below and justify your choice.
Proximity switch
Reason
Inductive proximity switch
Both proximity switches are contactless and require no mechanical actuation. Due to the fact that the trip cam is made of metal, the inductive proximity switch can be used. It functions in a contactless manner and is insensitive to contamination.
© Festo Didactic GmbH & Co. KG 541090
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Exercise 10: Stamping taper keys
Complete the circuit diagrams –
Complete the pneumatic circuit by drawing in the pressure sensor and the associated compressed air line. 1B1
1V2
1
1B3
4
1A1
1B2
1
1
2
2
1V3
2
U
3 1V1
4
2
5
3
1M1
1M2 1
Pneumatic circuit diagram
94
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys
–
Complete the electrical circuit diagram.
+24 V
1B1
1
3
2
5
4
1B3
1B2 BN
BN
RD
p
BK
BK
8
13
BK S1
U
12
14 12
14
K1
11 12
A1
A1 K2
0V
11
A1 K3
A2
14
K3 11
K1
14
K2
WH BU
BU
BU
7
6
1M1
A2
1M2
A2
11
12 14 .7
11
12 14 .8
11
12 14 .8
21
22 24
21
22 24
21
22 24
31
32 34
31
32 34
31
32 34
41
42 44
41
42 44
41
42 44
Electrical circuit diagram
© Festo Didactic GmbH & Co. KG 541090
95
Exercise 10: Stamping taper keys
Sequence description –
Set up the control system and describe the operating sequence. Initial position In its initial position, cylinder 1A1 is in the retracted end position. When cylinder 1A1 is in its retracted end position, magnetic proximity switch 1B1 is actuated (NO contact), relay K1 is energised and change-over contact K1 (connected as an NO contact) in current path 7 is closed.
Step 1-2 After activating pushbutton S1 (NO contact), solenoid coil 1M1 at 5/2-way double solenoid valve 1V1 is energised. Double solenoid valve 1V1 is reversed. Cylinder 1A1 advances. As soon as cylinder 1A1 leaves its retracted end position, proximity switch 1B1 is no longer actuated (NO contact). Change-over contact K1 (connected as an NO contact) in current path 7 is opened as a result and solenoid coil 1M1 is no longer energised. The double solenoid valve remains in the right-hand switching position.
Step 2-3 When the cylinder reaches the advanced end position, magnetic proximity switch 1B2 is activated (NO contact) and relay K2 is energised. Change-over contact K2 (connected as an NO contact) in current path 8 is closed. In the meantime, pressure sensor 1B3 measures pressure at cylinder 1A1. If pressure is equal to or greater than the selected setpoint, the pressure sensor is switched, relay K3 is energised and change-over contact K3 (connected as an NO contact) in current path 8 is closed. Solenoid coil 1M2 is now energised. As a result, valve 1V1 is returned to its normal position and cylinder 1A1 is returned to its retracted end position. As soon as proximity switch 1B2 (NO contact) is no longer actuated, relay K2 is de-energised and changeover contact K2 (connected as an NO contact) is opened. If the selected setpoint is fallen short of, the pressure sensor (programmed as an NO contact) is switched off, relay K3 is de-energised and change-over contact K3 (connected as an NO contact) in current path 8 is opened. As a result, coil 1M2 is also de-energised.
96
© Festo Didactic GmbH & Co. KG 541090
Exercise 10: Stamping taper keys
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
2
One-way flow control valve
2
Proximity switch, electronic
1
5/2-way double solenoid valve
1
Pressure sensor
1
Pushbutton (normally open)
3
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
© Festo Didactic GmbH & Co. KG 541090
97
Exercise 10: Stamping taper keys
98
© Festo Didactic GmbH & Co. KG 541090
Exercise 11: Palletising roof tiles Learning objectives After completing this exercise: • You’ll be able to make use of an optical sensor. • You’ll be familiar with displacement-step diagrams and learn to create them for specific problems. • You’ll be able to implement sequence control with two cylinders.
Presentation of the problem Stacks of roof tiles are strapped together. The resulting sets are then transported to a pallet loading station where they’re transferred to Euro pallets.
Layout
Pallet loading station
© Festo Didactic GmbH & Co. KG 541090
99
Exercise 11: Palletising roof tiles
Parameters Adjust the one-way flow control valve so that both cylinders are retracted at the same speed. The advanced end position of the single-acting cylinder will be detected with an optical sensor.
1 2 3 4 5 6 7 8
1 2 3
100
Project assignment Answer the questions and complete the tasks for the learning topics. Draw the displacement-step diagram. Create the associated function diagram and the function chart. Draw the pneumatic and electrical circuit diagrams. Simulate the electro-pneumatic circuit diagram and test it for correct functioning. Create an equipment list. Set up the pneumatic and electrical circuits. Check the circuit sequence.
Control sequence When pushbutton S1 is activated, cylinder 1A1 is advanced. An individual set is transported to the loading station as a result and sensor 1B2 is actuated. Cylinder 2A1 is advanced, actuates sensor 2B2 and pushes the individual set onto the pallet. If 2B2 is actuated and S1 is unactuated, cylinder 1A1 is retracted, 1B2 is no longer actuated and cylinder 2A1 is retracted. The overall sequence is thus as follows: 1A1+ 2A1+ 1A1– 2A1–
© Festo Didactic GmbH & Co. KG 541090
Exercise 11: Palletising roof tiles
Optical proximity switch, technical data –
Describe the mode of operation of the included optical proximity switch by entering its technical data in the table below. Use the respective data sheet to this end.
Technical data Switching voltage
10 to 30 V DC
Residual ripple
Max. 10%
Nominal switching distance
0 to 100 mm (adjustable)
Switching frequency
Max. 200 Hz
Output function
Normally open, positive switching
–
Write down what needs to be observed when setting up the circuit with regard to the position of the sensor. The sensor must be positioned so that only the cylinder’s trip cam is detected. There shouldn’t be any other objects within the sensor’s sensing range.
© Festo Didactic GmbH & Co. KG 541090
101
Exercise 11: Palletising roof tiles
Optical proximity switch, connection –
Sketch the power supply into the drawing shown below and connect the terminals at the optical sensor to the power supply. Enter the connections in the table. 24 V
RD BK BU
Circuit diagram, optical proximity switch
102
Socket
Connection
Red
24 V
Black
Relay (coil)
Blue
0V
© Festo Didactic GmbH & Co. KG 541090
Exercise 11: Palletising roof tiles
Creating a displacement-step diagram When pushbutton S1 is activated, cylinder 1A1 is advanced. An individual packet is transported to the loading station as a result and sensor 1B2 is actuated. Cylinder 2A1 is advanced, actuates sensor 2B2 and pushes the individual packet onto the pallet. If 2B2 is actuated and S1 is unactuated, cylinder 1A1 is retracted, 1B2 is no longer actuated and cylinder 2A1 is retracted. The overall sequence is thus as follows: 1A1+ 2A1+ 1A1– 2A1– –
Draw a displacement-step diagram for the task described above. S1
1 1
1A1
2
3
4=1
1B2
0
1
2B2
2A1 0 Displacement-step diagram
© Festo Didactic GmbH & Co. KG 541090
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Exercise 11: Palletising roof tiles
Complete the circuit diagrams – –
Complete the pneumatic circuit diagram for the pallet loading station. Complete the electrical circuit diagram for the pallet loading station. 1A1
1V2
1V1
2A1
1B2
2B2
1
1
2
2
4
2
5
3
1V3
2V2
1 2V1
1M1
2
2M1
1M2 1
2
1
3
Pneumatic circuit diagram +24 V
1B2
1
3
2
BN
2B2
5
4
BN
BK
13
BK
BU
S1
A1
7
12
14
K2 11
8
12
14
K1 11
11
A1 K3
A2
14
K3
A1 K2
0V
12
14
BU
K1
6
1M1
A2
1M2
2M1
A2
11
12 14 .8
11
12 14 .7
11
12 14 .6
21
22 24
21
22 24
21
22 24
31
32 34
31
32 34
31
32 34
41
42 44
41
42 44
41
42 44
Electrical circuit diagram
104
© Festo Didactic GmbH & Co. KG 541090
Exercise 11: Palletising roof tiles
Sequence description –
Set up the control system and describe the operating sequence. Initial position In their initial position, cylinders 1A1 and 2A1 are in the retracted end position.
Step 1-2 When pushbutton S1 (NO contact) is activated, relay K3 is energised. Change-over contact K3 (connected as an NO contact) is closed and solenoid coil 1M1 at 5/2-way double solenoid valve 1V1 is energised. Double solenoid valve 1V1 is reversed. Cylinder 1A1 advances. As soon as pushbutton S1 (NO contact) is no longer activated, relay K3 is de-energised and change-over contact K3 (connected as an NO contact) is opened. As a result, coil 1M1 is also de-energised.
Step 2-3 As soon as cylinder 1A1 reaches the advanced end position, magnetic proximity switch 1B2 (NO contact) is switched and relay K1 is energised. Change-over contact K1 (connected as an NO contact) in current path 8 is closed and solenoid coil 2M1 at 3/2-way solenoid valve 1V2 is energised. Valve 2M1 is reversed and cylinder 2A1 advances.
Step 3-4 When cylinder 2A1 reaches the advanced end position, optical proximity switch 2B2 is activated (NO contact) and relay K2 is energised. Change-over contact K2 (connected as an NO contact) in current path 7 is closed. Solenoid coil 1M2 is now energised. As a result, valve 1V1 is returned to its normal position and cylinder 1A1 is returned to its retracted end position. As soon as cylinder 1A1 has left its advanced end position, relay K1 is de-energised. NO contact K1 in current path 8 opens and solenoid coil 2M1 is de-energised. Valve 1V1 is returned to its normal position by the reset spring and cylinder 2A1 is returned to its retracted end position.
© Festo Didactic GmbH & Co. KG 541090
105
Exercise 11: Palletising roof tiles
Create an equipment list In addition to the circuit diagram, complete project documentation also includes an equipment list. –
Create an equipment list by entering the required components in the table below.
Quantity
Designation
1
Cylinder, double-acting
1
Cylinder, single-acting
3
One-way flow control valve
1
5/2-way double solenoid valve
1
3/2-way solenoid valve
1
Proximity switch, electronic
1
Proximity switch, optical
1
Pushbutton (normally open)
3
Relay
1
Distributor block
1
On-off valve with filter regulator
1
Compressed air source
1
Power supply unit, 24 V DC
Equipment list
106
© Festo Didactic GmbH & Co. KG 541090
Exercise12: Eliminating a malfunction at a pallet loading station Learning objectives After completing this exercise: • You’ll be able to detect and eliminate errors in simple electro-pneumatic control systems.
Presentation of the problem The pallet loading station comes to a standstill during operation. A malfunction has occurred and must be eliminated. Afterwards, the pallet loading station must be restarted.
Layout
Pallet loading station
© Festo Didactic GmbH & Co. KG 541090
107
Exercise12: Eliminating a malfunction at a pallet loading station
Parameters A malfunction has occurred.
1 2 3 4
1 2 3
108
Project assignment Describe the control system’s performance. Compare this with the correct performance. Make use of the displacement-step diagram. Narrow down possible causes of the malfunction. Make use of the pneumatic and electrical circuit diagrams. Pinpoint the malfunction at the control system and eliminate it. Put the control system back into service.
Control sequence When pushbutton S1 is activated, cylinder 1A1 is advanced. An individual set is transported to the loading station as a result and sensor 1B2 is actuated. Cylinder 2A1 is advanced, actuates sensor 2B2 and pushes the individual set onto the pallet. If 2B2 is actuated and S1 is unactuated, cylinder 1A1 is retracted, 1B2 is no longer actuated and cylinder 2A1 is retracted. The overall sequence is thus as follows: 1A1+ 2A1+ 1A1– 2A1–
© Festo Didactic GmbH & Co. KG 541090
Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting simple electro-pneumatic circuits The following error occurs in the control system depicted below: The piston rods in cylinders 1A1 and 2A1 advance and remain in the advanced end position. –
Describe the possible causes of this error. 1A1
1V2
1V1
2A1
1B2
2B2
1
1
2
2
4
2
5
3
1M1
1V3
2
1 2V1 1M2
1
2V2
2M1
2
1
3
Pneumatic circuit diagram
© Festo Didactic GmbH & Co. KG 541090
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Exercise12: Eliminating a malfunction at a pallet loading station
+24 V
1B2
1
3
2
BN
2B2
5
4
BN
BK
13
BK
BU
S1 14
A1
A1 K2
14
7
12
14
K2 11
8
12
14
K1 11
11
A1 K3
A2 0V
12 K3
BU
K1
6
1M1
A2
1M2
2M1
A2
11
12 14 .8
11
12 14 .7
11
12 14 .6
21
22 24
21
22 24
21
22 24
31
32 34
31
32 34
31
32 34
41
42 44
41
42 44
41
42 44
Electrical circuit diagram
List of possible causes Sensor 2B2 at cylinder 2A1 is incorrectly adjusted, defective sensor Current path 3 is interrupted (e.g. broken wire or loose connection) The signal cable from sensor 2B2 is interrupted, current path 4 (e.g. broken wire or loose connection) Earth cable 1M2 is interrupted, current path 7 (e.g. broken wire or loose connection), solenoid coil 1M2 is defective Earth cable at relay K2 is interrupted, current path 4 (e.g. broken wire or loose connection), relay K2 is defective Interruption of current path 7, supply line to relay contact 14 (relay K2) or supply line to relay contact 11 (relay K2) downstream from solenoid coil 1M2 (e.g. broken wire or loose connection)
110
© Festo Didactic GmbH & Co. KG 541090
Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting simple electro-pneumatic circuits Conductors are interrupted at the points identified in the circuit shown below. –
Explain which effects a broken wire would have on the circuit’s function at each of the identified points.
+24 V
1B2
1
3
2
5
4
2B2 BN
BN BK
6
13
BK
S1
12
14 BU
14
K3
7
12
14
K2 11
8
12
14
K1 11
11
BU
A1 K1
A1 K2
A2 0V 11
12 14 .8
21
22 24
31
32 34
41
42 44
A1 K3
1M1
A2
1M2
2M1
A2
11
12 14 .7
11
12 14 .6
21
22 24
21
22 24
31
32 34
31
32 34
41
42 44
41
42 44
Electrical circuit diagram
Error
Effects of the error
Broken earth wire at relay K1, current path 2
Piston rod in cylinder 1A1 advances, sensor 1B2 is actuated => relay K1 is not picked up => relay contact in current path 8 (change-over contact, connected as NO contact) does not switch => piston rod in cylinder 2A1 does not advance to the advanced end position (remains retracted), sensor 2B2 is not actuated => piston rod in cylinder 1A1 remains advanced because 1M2 is not actuated.
Broken signal wire at
Piston rod in cylinder 1A1 advances, sensor 1B2 is actuated => piston rod in cylinder 2A1 advances to
sensor 2B2, current path 4
the advanced end position, sensor 2B2 is actuated => relay K2 is not picked up => relay contact in current path 7 (change-over contact, connected as NO contact) does not switch => piston rods in cylinders 1A1 and 2A1 remain in the advanced position.
Broken supply line to relay K3, current path 5
Current path 5 is not closed, relay K3 is not picked up, no reaction to start signal => piston rods in cylinders 1A1 and 2A1 remain in the retracted position.
Broken supply line to relay
Piston rod in cylinder 1A1 advances, sensor 1B2 is actuated => piston rod in cylinder 2A1 advances to
contact 14 (relay K2), current path 7
the advanced end position, sensor 2B2 is actuated => relay K2 is picked up, relay contact in current
Earth wire 2M1 broken,
Piston rod in cylinder 1A1 advances => sensor 1B2 is actuated => relay K1 is picked up, relay contact in
current path 8
current path 8 (change-over contact, connected as NO contact) switches, but solenoid coil 2M1 is not
path 7 (change-over contact, connected as NO contact) switches, but solenoid coil 1M2 is not energised due to broken wire => piston rods in cylinders 1A1 and 2A1 remain in the advanced position.
energised due to broken wire => piston rod in cylinder 2A1 remains retracted, piston rod in cylinder 1A1 remains advanced.
© Festo Didactic GmbH & Co. KG 541090
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Exercise12: Eliminating a malfunction at a pallet loading station
Error list for possible error simulation by the trainer The following is a list of errors which you can incorporate into a control system. The corresponding printed forms for troubleshooting are in the student workbook. Error simulation
Cause of error
Effects of the error
Push sensor 1B2 at cylinder 1A1 towards the retracted end position.
Sensor 1B2 at cylinder 1A1 is incorrectly adjusted.
Piston rod in cylinder 1A1 advances, sensor 1B2 is briefly actuated => piston rod in cylinder 2A1 does not advance into the advanced end position, sensor 2B2 is not actuated => piston rod in cylinder 1A1 remains advanced because 1M2 is not actuated.
Disconnect the signal cable from sensor 1B2 or push the sensor beyond the advanced end position.
Broken signal cable at sensor 1B1 or incorrectly adjusted sensor.
Piston rod in cylinder 1A1 advances => no sensor signal or sensor 1B2 is not actuated => piston rod in cylinder 2A1 remains retracted, piston rod in cylinder 1A1 remains advanced.
Disconnect the signal cable from sensor
Broken signal cable at sensor 2B1 or
Piston rod in cylinder 1A1 advances,
2B2 or push the sensor beyond the advanced end position.
incorrectly adjusted sensor.
sensor 1B2 is actuated => piston rod in cylinder 2A1 advances into the advanced end position, no sensor signal or sensor 2B2 is not actuated => piston rods in cylinders 1A1 and 2A1 remain in the advanced position.
Interrupt current path 2 (e.g. earth wire
Broken earth wire 2M1, K1 and supply from relay K1), signal line or current path 8, lines to relay contact 11 and 14 (relay K1)
Piston rod in cylinder 1A1 advances => 2A1
e.g. disconnect supply lines to relay
remains retracted because current paths 2 and 8 are interrupted.
contact 14 or 11 (relay K1) and earth wire 2M1. For example, interrupt earth wire from
Broken earth wire 1M2, K2 and supply lines to relay contact 11 and 14 (relay K12)
The piston rods in cylinders 1A1 and 2A1
Interrupt earth wire from relay K3, current
Broken earth wire 1M1, K3 and broken
No reaction to start signal => piston rods in
path 5 or 8, 1M1, or disconnect K3 and supply lines to relay contact 14 and K3.
supply lines to relay contact 14 to K3
cylinders 1A1 and 2A1 remain in the retracted position.
relay K2 and current path 4 or 7, or disconnect relay K2 and supply lines to
advance and remain in the advanced end position.
relay contacts 14 and 11 (relay K2) and earth wire1M2.
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Exercise12: Eliminating a malfunction at a pallet loading station
Notes for the trainer It’s advisable to carry out this task after setting up the control system, because correct set-up of the control system has then been completed and tested. The error can be directly incorporated into the control system by the trainer (see error simulation list). It’s important to make sure that the trainees proceed in an orderly fashion during troubleshooting. Alternative If a fully set-up control system is not available, troubleshooting can also be conducted theoretically. The trainer explains the malfunction (“cylinder 1A1 advances and then the control system jams”). The trainees narrow down the possible errors based on the function chart. The trainees prepare a list of possible causes of the error and describe how they will proceed during troubleshooting (where must measurements be performed, what must be tested).
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Exercise12: Eliminating a malfunction at a pallet loading station
Determine target status –
Create a displacement-step diagram of the target status with the help of the necessary documentation. Zeit
Bauglieder
Schritt Benennung
Kennzeichnung
1 Signal
2
3
4
5
6
7
8
9
10
Displacement-step diagram
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: actual versus target status comparison –
Determine the actual status of the system on the basis of the following documentation: Layout with description of the problem Graphic representation If correct functioning is not ensured (actual versus target status comparison), clearly mark the point in the diagram where the error occurs. Zeit
Bauglieder
Schritt Benennung
Kennzeichnung
1 Signal
2
3
4
5
6
7
8
9
10
Displacement-step diagram
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: description of the error You marked the point at which the error occurs in the diagram on the worksheet for the actual versus target status comparison. –
Describe in a few words the sequence up to the point that the station or system comes to a standstill.
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: pinpointing pneumatic errors After having determined the system’s actual status, think about what might have caused the error. In which pneumatic tubing connections might the error be located? –
Enter all possibilities. Specify elements at the beginnings and ends of tubing connections in order to ensure clear identification.
Error possibility no.
Tubing connection, beginning
Tubing connection, end
Possible errors
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: pinpointing electrical errors After having determined the system’s actual status, think about what might have caused the error. In which current paths might the error be located? What is the function of the current path? –
Enter all possible errors in the table.
Error possibility no.
Current path no.
Function of the current path
Possible errors
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: narrowing down pneumatic errors Examine the possible pneumatic causes of error which you have discovered. Use the same error numbering you used on the worksheet for pinpointing pneumatic errors. Document the procedure used for inspecting the tubing connections. –
Enter the results of your inspection in the following table.
Measuring and test report Error possibility no.
Tubing connection, beginning
Tubing connection, end
Inspection
Results
Measuring and test report
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Exercise12: Eliminating a malfunction at a pallet loading station
Troubleshooting: narrowing down electrical errors Examine the possible electrical causes of error which you have discovered. Use the same error numbering you used in the worksheet for pinpointing electrical errors. –
Document the procedure used for inspecting the wiring connections by entering your results in the table.
Measuring and test report Error possibility no.
Current path no.
Measuring points
Inspection
Results
Measuring and test report
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Exercise12: Eliminating a malfunction at a pallet loading station
Error elimination After pinpointing the error, document the procedure for eliminating the error on this worksheet. –
Describe each step as completely as possible.
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Note If the system does not fulfil the desired function, go back to the first worksheet and repeat the troubleshooting process. Use new worksheets for this.
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Exercise12: Eliminating a malfunction at a pallet loading station
Commissioning After having detected, localised and eliminated the error or errors, re-start the system in accordance with the target status. Reset the specified setpoint times. –
Describe your procedure in a few words.
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