GB1114234A - Control systems - Google Patents

Abstract

1,114,234. Forging presses. DAVY & UNITED ENGINEERING CO. Ltd. 17 Dec., 1964 [21 Dec., 1963], No. 50595/63. Heading B3H. An automatic control system for a reciprocating member, particularly a forging press platen, comprises means for monitoring the position of the member and settable means for determining its stroke. An hydraulic forging press has its platen 13, Fig. 1, actuated by pressure liquid supplied to a double-acting piston 101 in hydraulic cylinder (100), Fig. 2 (not shown), by a pump (104) through a shutoff valve (106) and a reversing valve (111). The pressure liquid acts continuously on the underside of piston (101) and is supplied to the top side of the piston, to effect the forging stroke, when valve (111) is moved upwardly by its spring (112). This valve (111) may be controlled manually by solenoid valve (122) through ram (113), or automatically through solenoid valve (123) through ram (114). Stop valve (106) is actuated by ram (107) which may be controlled manually by solenoid valve (120) or automatically by solenoid valve (121). The control rams are fed by a pilot pump (117). Automatic control.-Movement of the platen 13, Fig. 1 (not shown), actuates a pair of pulse generators 18, 19 whose signals are passed through serializer 20 and dividing circuit 21 to a first counter 22 whose output is passed to a coincidence unit 25A where it is compared, during the forging stroke, with a lower stroke position set by dials 16. When the two signals differ by a small fixed amount, an output signal is released on line 26 to actuate a flip-flop 27 and an adjustable timing circuit 28. The flipflop opens a gate 30 permitting pulses on line 21b to pass through a gate 31 to another counter 32. The timer 28 also opens a gate 40 permitting pulses from line 20b to pass from delay circuit 41 to gate 31 and counter 32; these pulses represent the mean speed of the platen to compensate for its inertia. When the count at 32 equals the small fixed amount, a signal is passed along line 33 and gate 34 to trigger generator 35 which actuates the winding 37 of lift solenoid 133, thereby reversing the platen. Instead of setting the lower limit, a predetermined penetration of the workpiece may be set on dial 17. When the upper tool 14 contacts the workpiece, the hydraulic pressure rise in line (102), Fig. 2 (not shown), is passed to a line 62 which opens a gate 63 permitting pulses 21b to pass into a further counter 65 whose output is compared in a coincidence unit 66 with the pre-set penetration on dial 17. Unit 66 emits a signal at the appropriate time to operate flip-flop 27A and timer 28A which actuate the lift solenoid at the set penetration. During retraction of the platen, the pulses are passed to a further counter 47 whose output is compared in a coincidence unit 48 with the desired upstroke set on dial 25. At the appropriate platen position an output signal is emitted to a trigger generator 52 to actuate the forge solenoid winding 53 and a further signal operates a dwell timer 54 which controls the stop valve (106) for a dwell period adjustable by control 57. On initiation of the next downward stroke, the counter 47 is reset. The pulse generators may also be applied to operate an eccentric loading sensing circuit 68 as described in Specification 1,017,994.