GB1285877A - Power press having a fluidic control system - Google Patents

Abstract

1285877 Fluid logic switching circuits PRESSED STEEL FISHER Ltd 18 Nov 1969 [19 Aug 1968] 39546/68 Heading F1P A fluid logic switching circuit suitable for controlling a press comprises a flip-flop 14 having a first output 14d serving to engage the press clutch, a foot switch 17 or 18 which when operated causes the flip-flop to deliver to said output 14d, a further switch e. g. air valve 37 which when closed results in the flip-flop 14 assuming its other position and fluidic gates inter-connected between switch 17, 18 and flip-flop 14 and adapted on continued operation of the foot switch to prevent the flip-flop from being moved from the second to the first position after operation of valve 37 but allowing a renewed operation of the flip-flop to do so. The control system allows the press to effect single strokes, continuous strokes and inching according to the position of ganged selector switches 34a, 34b connected to a valved main air line 6. To prepare the circuit a valve 7 is opened and with all inputs of flip-flops 14, 15, 16 pressurized, the flip-flops lock in their upper positions shown *. A '1' output at 14b is applied to input 12a of AND gate 12 and a '1' output is also supplied at 12b from output 19b of a NOT gate 19 which at present has a '0' input. The resulting '1' output at 12c is applied to the bottom input 15b of flip-flop 15 whereby a '1' output appears at 15c and is applied to input 11α. This signal is also applied to input 13α of AND gate 13 which thus has '1' output at 13b which is applied to input 14c and so locks 14 on top. Single-stroke operation is effected by closing switches 34α, 34b in SS, position and closing say switch 17 thereby providing a '1' input at 19α and a '0' output at 19b whereon the '1' signal at 12b, 13c, and flip-flop 14, 15 switch to their lower positions. Closing of switch 17 also provides a '1' input at 11b and since there is a '1' input at 11α a '1' output of gate 11 is applied to 14α which locks 14 in its lower position so that a '1' output is applied at 25α of NOR gate 25 so that its output is '0' whilst that of a NOR gate 26 is '1' which signal switches a step up relay 46 to connect main line pressure to the clutch valve (not shown). The '1' output at 14d also feeds input 15α so that flip-flop 15 locks on to its lower position and AND gate 13 switches off. As the press main approaches T.D.C. on the upstroke, valve 37 is mechanically opened to provide a '1' signal at input 20α of NOT gate 20. The resulting '0' signal at 20b is applied to input 27α of NOR gate 20 which thus has a '1' output at 27b which is applied to input 14e to move flip-flop 14 to its upper position. Consequently the output at 14d is '0', relay valve switches off and the press main stops at T. D. C. The output at 14b changes from '0' to '1' and this is applied to input 16α of flip-flop 16 causing a '1' output to be fed to input 27c or NOR gate 27 the output which is thus reduced to '0'. Thereafter any signal to NOR gate 27 cannot switch flip-flop 14. To effect continuous stroke operation switch 34α, 34b is positioned, the foot switch 17 or 18 is actuated and the sequence is the same as for simple-stroke operation except that valve 17 cannot trap the press because input 27d of NOR 27 received a '1' signal from switch 34b so suppressing any signal on 27b. To "inch" the press, switch 34α, b is positioned whereon a '1' signal is applied to input 28α of NOR 28 and an '0' signal at 28b and is applied to 22α to give a '1' output at 22b which is fed to input 14f to flip-flop 14 to give an output at 14b. Thus the press cannot be stroked by foot switch 17 or 18. When button 29 is pressed a '1' signal is applied to 25b to operate relay 46 press moves only as long as button 29 is pressed. The circuit also provides for micro-inching and stopping.