Patent GB-962478-A (GB)
Title: Knife changing controls for paper cutting machines
IPC: B26D7/26
Filed: 1961-12-04
Abstract: 962,478. Guillotine cutting - machines. MIEHLE - GOSS - DEXTER Inc. Dec. 4, 1961 [Dec. 9, 1960], No. 43308/61. Heading B4B. In a guillotine cutting-machine in which the knife to be secured to the knife bar is temporarily attached to a clamp operable by an hydraulic piston and cylinder, means are provided for effecting restricted flow from the exhaust end of the cylinder when the clamp is being moved upwardly. As shown in Fig. 1, the clamp cylinder is connected intermediate its ends by ducts 33, 34 to a check valve comprising a casing 31 which contains a free piston 38 and a ball 42 spring-biased against its seat 42a. Casing 31 to the rear of ball 42 is connected by a duct 45 to a chamber 47 between the piston 38 and ball 42 and to a clamp operating valve 25 which is controlled by a solenoid 25a, Fig. 2. A needle valve 50 in the duct 45 meters the flow from chamber 10 of clamp cylinder to valve 25 from which oil passes via duct 52 to the tank. A normally-open valve 36 controlled by solenoid 36a, Fig. 2, is provided in duct 34. A valve 28 operable by solenoid 28a, Fig. 2, effects actuation of a throw-in cylinder for alternately engaging the brake and clutch for the knifeactuating mechanism. The circuit, Fig. 2, includes switches K-1, K-2 controlled by knifeholding washers. Closure of switch K-1 energizes solenoid 36a to close valve 36 to enable exhaust from chamber 10 to be metered for slowing the rate of ascent of the clamp. At this time, switch K-2 is open and this prevents current from passing to the push-buttons so that it is not possible to cycle the knife. Closure of switch K-2 and opening of switch K-1 deenergizes solenoid 36a to open valve 36 to unseat ball 42 while the closure of switch K-2 permits energization of the knife operating cycle. The open condition of switch K-2 disconnects the entire operating circuit so that the clamp cannot be operated by solenoid control. However, the clamp valve 25 can be operated by the machine foot treadle so as to effect the position of valve 25, as shown in solid lines in Fig. 1, in order to provide pressure fluid to the clamp cylinder for raising the clamp. The knife-holding washers 155, Fig. 3, have screwed heads threaded into bores of machine frame 158 and engage threaded adjusting pins 162 mounted on a bar 165 which is carried at its ends in slots in the sides of a strap 171 having its feet secured to frame 158. Pins 177 allow a predetermined rocking of bar 165. A spring- biased rod 183 carries a pole co-operable with the switches K-1 and K-2. With the rod 183 in the position shown, the switch K-1 is closed and the switch K-2 is open to conform to the condition of Fig. 2. Should, however, either washer 155 be removed, the rod 183 will drop, whereby switch K-1 will open and switch K-2 close. In an alternative arrangement, switch K-1 is operable directly by the foot treadle so that any time the foot treadle is depressed, the clamp will slowly rise. Thus the safety arrangement of Fig. 3 would involve only switch K-2. In such case, full release of the foot treadle would permit switch K-1 to open, for example, for rapid rise of the clamp. Specification 844,578 is referred to.