Patent GB-1452043-A (GB)
Title: Press brake ram controlling apparatus and method
IPC: G05B19/4093
Filed: 1975-02-18
Abstract: 1452043 Press brake ram control HURCO MFG CO Inc 18 Feb 1975 [19 Feb 1974] 6794/75 Heading B3E [Also in Division G3] A method of making a series of bends on a workpiece in a press brake comprises establishing a program and entering into a controller a set of ram closed and ram open position designating signals representative of a series of positions to be reached and temporarily maintained, in a sequence, by the press brake ram 14, Fig. 1, locating a workpiece between dies 17, 18 of the press brake and actuating the ram to make a first bend, limiting the closing stroke of the ram according to a first ram closing position designating signal entered in the controller, limiting the return stroke according to a first ram open position designating signal entered in the controller, relocating the workpiece, actuating the ram to make a second bend, closing and returning the ram to limits predetermined by respective position designating signals entered into the controller for a second bend, and repositioning the workpiece after opening the ram on succeeding closures thereof to make additional bends in the workpiece. Sets of ram-closed dimension switches and ram-open height switches are included in respective blocks 40, 45, Fig. 8, and their outputs are coupled to thumbwheel switch multiplexers 56, 57 having inputs from a sequence control logic 58. The multiplexer outputs 56, 57 are coupled to a dimension register/counter 59 and a height register 61 which are coupled in turn to a multiplexer 62. An encoder 67, mounted on a bracket 68 to the cross member 13 of the press brake, has two pulse train outputs, phases A, B, with a 90 degree phase difference for passage to an encoder logic 66. Output from the encoder logic is passed to a true-position counter/register 64 and thence to the multiplexer 62. The output of the multiplexer 62 is fed to a comparator 63. A top of stroke detector 71 has inputs from output 72 and the sequence control logic and its output 77 is connected in parallel with the top of stroke limit switch 24. A bottom of stroke detector 73 has inputs from outputs 72, 74 and the sequence control logic and its output 76 is connected in parallel with the bottom of stroke limit switch 22. Cycle control switches in box 92 determine whether or not the system will stay at a station for one closing stroke of the ram or up to a total of nine closing strokes before advancing to the next station. A bias counter 87 is loaded with the conditions of offset switches 49. The dimension counter 59 is simultaneously counted up or down until underflow is detected from the bias counter 87. Both counters 59, 64 are not permitted to count below zero thus avoiding possible damage to dies if an erroneous minus offset were manually entered. The sequence control logic 58 includes a state counter and decoder and a station counter and decoder. The multiplexer 62 selects, on alternate phases of a phase X, phase Y clock of the control logic, the ram-open height register 61 or ram-closed dimension register 59, for input in to the comparator 63. If the contents of counter 64 are greater than those of register 61 at the phase X clock pulse, output 77 commands the ram to stop die opening travel. The bottom of stroke detector 72 is set during a phase 7 clock pulse whenever the count of the counter 64 is less than the contents of register 61 and an output 76 commands the ram to return to the open position. The output 76 is maintained until the ram has reached the full open position. The gauge control 91 is co-ordinated with the ram stroke depth control by a signal from the sequence control logic 58 to the gauge control after the ram has reached the bottom of its stroke.