GB810989A - Improvements in or relating to power presses - Google Patents

Abstract

810,989. Controlling clutches; change-speed gearing. SCHULER A.G., L. July 26, 1956 [Aug. 2, 1955], No. 23174/56. Class 80 (2). In a press having at least one brake and one clutch, particularly a press having changespeed gear with a separate clutch for every speed and in which the idle stroke is passed more rapidly, each clutch or brake control comprises a control member connected to the control of the other clutches or brakes such that engagement of the latter is blocked until the former clutch or brake is disengaged. A motor 1 drives the two crankshafts of a press through two-speed gearing 5, 7 or 3, 4, on engagement of friction clutches 9, 10 respectively, which are engaged by fluid pressure in cylinders 13, 14 moving piston rods within the driving shaft 6 to actuate collars 29, 29<SP>1</SP> and links 30, 30<SP>1</SP>. A friction brake 15 is rigid with the body of the press and connected to the shaft 6 and is engaged by springs 57, compressed under disengaged conditions by a fluid pressure cylinder 35. The cylinders 13, 14, 35 are connected to a pressure source 63 through pipes 36, 33, 34, respectively which includes electromagneticallyoperatedcontrol valves 42, 38, 40 and pressurecontrol devices 43, 45, 41. The pressure control devices comprise a spring-loaded piston subject to the pressure in the pipe such that at the end stroke a micro-switch w2, w1 or wbris operated. Fine cams 46, 47, 48, 49 and 50 are driven synchronously with the press crankshaft and control fine switches 51, 52, 53, 54 and 55 respectively. The electrical circuit shown in Fig. 4, in which relays A to J control switches a to j respectively, is arranged such that on actuation of the two ON switches the pressure fluid flows to the cylinder 35 to release the brake, pressure build-up in line 34 trips the control device 41 to allow pressure to pass to cylinder 13 to engage clutch 9 and run the press on its work stroke at low speed. At the end of the work stroke as determined by the relative position of the cams 46-50, clutch 9 is disengaged, and when disengaged, clutch 10 is engaged for a fast idle stroke of the press. At the end of the stroke clutch 10 is disengaged and then the brake is engaged. A switch 56 has three positions which correspond to : I press runs only while ON switch is depressed; II press runs with ON switch depressed to end of cycle; III press runs continuously after depression of ON switch.