GB944624A - Improvements relating to crimping - Google Patents

Abstract

944,624. Jointing by stamping. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. May 25, 1962 [June 8, 1961], No. 20765/61. Heading B3Q. A power-operated crimping machine comprises an hydraulically-operable ram and a shaped die or anvil and pump means for applying hydraulic pressure to the ram in a closed condition of a solenoid-operated hydraulic valve which can be. opened at the end of a crimping operation to release said hydraulic pressure. The machine comprises a constant stroke oil pump 1, e.g. a swash-plate type, driven continuously by a 3-phase electric motor 2, which includes a rotary valve 5 actuated from the open to the closed position by an energized solenoid 6 by rotation of a valve spindle 7 through a linkage 8. The valve 5 is connected by a pipe line 9 to a ram 10 which co-operates with die 12 shaped to effect a crimping operation on a cable terminal assembly. The pipe line 9 includes a pressureresponsive change-over switch 13, the moving contact of which is displaced in an anti-clockwise direction. A relay unit 10 comprises an energizing winding 16 with a pair of normally open contacts 17 and 18. A single-phase current is supplied to the relay 10<SP>1</SP> and solenoid 6. In operation, an assembly is positioned on the die 12 and a foot switch operated to close the contacts 15 and energize a circuit for the relay 10<SP>1</SP> which causes the solenoid 6 to be energized over closed contacts 17 to effect closure of the valve 5. The energizing circuit of the relay 10<SP>1</SP> includes a load resistor 19 in addition to the moving contact 14 and a non- adjustable fixed contact of the switch 13, and in operation completes its own holding circuit by the closure of contacts 18, therefore keeping the valve 5 closed upon the interruption of the initial energizing path of the relay as the pressure builds up and the moving contact 14 disengages the non-adjustable fixed contact. At the pre-set pressure, e.g. 10,000 p.s.i., the moving contact 14 engages the adjustable fixed contact to short-circuit the relay 10<SP>1</SP> and winding 16 causing the contacts 17 to open, interrupt the solenoid 6 circuit and bring about the opening of the valve 5 which in turn permits the die to open under the influence of a return spring (not shown). In the event of a pump failure the solenoid is de-energized by a switching means (not shown). A manually-operated switch 20 opens the motor circuit and a normally closed magnetic safety switch 21 fitted to a safety guard is connected in series with the switch 20 so that the motor will not operate unless the guard is effective. A spring-loaded safety valve may be fitted to the hydraulic system and abutments on the ram 10 and die 12 co-operate to prevent excessive loading of the cable assembly during crimping.