• Author / Uploaded
• Fernando Pauli Prado

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DESIGN OF MACHINERY 3rd Ed.

by ROBERT L. NORTON

reed

© McGraw-Hill 2004

water-jet orifice

incoming threads (warp)

"shot" thread (weave)

cloth

crank coupler ωin

laybar

rocker

4-bar linkage

(a) Warp, weave, laybar, reed, and laybar drive for a water-jet loom

coupler 8.375"

ωin crank 2"

beat-up force

reed laybar

reed

beat-up force 540 lb

r = 3.75"

inertia force

ground 9.625" @ –43°

500 rpm

laybar inertia force

rocker 7.187"

(b) Linkage, laybar, reed, and dimensions

accelerations 4 169 in/sec2

7 834 in/sec2

(c) Acceleration on laybar and force on reed

FIGURE P11-6 Problem 11-13 - Fourbar linkage for laybar drive, showing forces and accelerations on laybar

†11-13

Figure P11-6 shows a water jet loom laybar drive mechanism driven by a pair of Grashof crank rocker fourbar linkages. The crank rotates at 500 rpm. The laybar is carried between the coupler-rocker joints of the two linkages at their respective instant centers I3,4. The combined weight of the reed and laybar is 29 lb. A 540-lb beat-up force from the cloth is applied to the reed as shown. The steel links have a 2 x 1 in uniform cross section. Find the forces on the pins for one revolution of the crank. Find the torque-time function required to drive the system.

†

These problems are suited to solution using Mathcad, Matlab, or TKSolver equation solver programs. In most cases, your solution can be checked with program FOURBAR.