GB957076A - Improvements in gang or multiple presses - Google Patents

Abstract

957,076. Metal working presses. L. SCHULER A.G. Sept. 8, 1961 [Oct. 29, 1960], No. 32297/61. Heading B3H. A system for monitoring the transfer of workpieces 2, Fig. 2, in a gang or multiple press comprises a relay C, Fig. 3b, which controls the operation of the press ram and whose exciting circuit 7 contains a contact u which is opened periodically in synchronism with the ram operation or the workpiece transfer, said contact being by-passed, when a blank is properly ejected and transferred by a second circuit 8 containing contacts I, II, III, N in series, each controlled by a monitoring unit 5 at a working station of the press, and at least some of the contacts are adapted to be bridged separately by a contact d<SP>1</SP> 4 of a relay which operates wherever the monitoring unit associated with the preceding station indicates the absence of a workpiece during the preceding working stroke. This enables the press to perform some idle strokes without stopping whilst fresh workpieces such as 2<SP>1</SP> are supplied to, or a fresh strip of material is supplied to, a pre-working station. The workpieces are transferred by grippers 4 mounted on rails 3 which move inwardly for gripping the blank and then transfer it to the next station. At each station there is a monitoring device consisting of a detector finger 5 actuating a switch 6. The relays may be operated by impulses derived from a cam-operated or rotary switch driven in synchronism with the press ram, which is operated through a clutch controlled by relay C. The contacts I, II, III, N actuated by the fingers 5, are removable from the circuit 8 by plug and socket connections 9. When any of these contacts are open in the circuit 8 they operate, through a circuit 12, one or more warning indicators L. A bridging circuit 13 with contact Si is used to render the monitoring system inoperative.