GB1060655A - Improvements in or relating to apparatus for electrically controlling the energization of a current operated device and presses controlled thereby - Google Patents

Abstract

1,060,655. Clicking presses. BRITISH UNITED SHOE MACHINERY CO. Ltd. Oct. 16, 1963 [Oct. 17, 1962], No. 40751/63. Heading B4B. [Also in Divisions F2 and H3] The stroke of an hydraulically-operated press is terminated by the contact of a conductive movable platen 20 and cutting die 16, with a conductive cutting pad 12, controlling a solenoid valve in the hydraulic circuit. The solenoid S is electrically controlled by a circuit (see Division H3) comprising a pair of transistors in a " lockup " circuit which on receipt of a signal from an operator-controlled device 40 cause the solenoid valve to initiate descent of the platen and maintain the valve operative until the circuit is again triggered by receipt of a second signal to cause the valve to terminate the descent. In operation, downward movement of a handle 40 causes the beam 18 to be moved downwards by energization of the solenoid S, the downward movement being terminated by de-energization of the solenoid when an electric circuit is established through the platen 20, die 16 and pad 12. If, during the stroke, the hydraulic pressure exceeds a predetermined amount a pressure-operated switch 50 closes a contact 52 to release pressure in the upper chamber of the hydraulic motor 24. The stroke is terminated in the event of contact of any earthed body, e.g. the operator's hand, with the platen.