Patent GB-651133-A (GB)
Title: Stock feeding mechanism for punching, stamping and cutting machines
IPC: B21D43/11
Filed: 1948-02-17
Abstract: 651,133. Metal-strip feeds. HALLER, J. Feb. 17, 1948, No. 4591. Convention date, Feb. 8, 1945. [Class 83 (iv)] Strip feed mechanism for stamping and like presses comprises a reciprocating feed means operated by a fluid motor controlled by a pump operatively connected to the reciprocating head of the press and means for adjusting the stroke of the feeding means. The feed mechanism is shown applied to a punching machine comprising a die 8 and punching head 6, Fig. 14, the main casting 10 of the feed mechanism being bolted to the bolster platform 5. The strip S passes between two vertical positioning rollers 93, beneath a friction roller 107 which can rotate only in the feeding direction and through a horizontal slot in a reciprocable feeding carriage 18, Fig. 2. The carriage is mounted on a driving piston rod 24 with slight longitudinal play provided by the spacing between an abutment 28 and a nut and washer 30, so that on the rod beginning to move in the feeding direction, a bent lever 33 pivoted within the carriage and having an arm depending into a slot in the rod 24 is turned slightly clockwise to bring a sharp edge 35 into gripping engagement with the underside of the strip. On the backward movement of the carriage, the lever is moved anticlockwise sufficiently to disengage the edge 35 from the strip, which is held against backward movement by the friction, roller 107. The pressure between the roller and the strip may be adjusted by a screw 114 which acts through a spring on part of a hinged casing 100 within which the roller is mounted. At its other end the rod 24 passes into a cylinder 20 and carries a piston 26. This piston and the end of the rod is internally screw threaded and receives an externally threaded hollow rod carrying a piston 55. Into one end of this rod is keyed a shaft 58 carrying outside the cylinder, a pinion 65 meshing with a pinion 66 on a shaft 68 formed with polygonal end 77 to receive a manually operable crank. By turning the crank, the distance between the pistons 26 and 55 may be altered so as to adjust the amount of longitudinal movement of the rod 24 and hence of the feed carriage 18. Integral with the shaft 68 is a screw 71 along which moves an indicator arm co-operating with a graduated scale and another screw 74 along which moves a positive carriage stop 79. At the end of a stroke in either direction, the movement of the rod 24 is cushioned by means of enlargements 25, adjacent the pistons which enter enlarged bores in the cylinder end caps 21, from which bores, fluid may pass by way of bleeder ports 82. In operation, pressure fluid is supplied alternaately to the two ends of the cylinder 20 by way ,of ducts 182 and 183 in the casting from a cylinder 125, under the control of the punch head 6 of the machine. Bolted to the head 6 is an angle bracket 176 which at its other end engages a roller carried by a block 169 slidably adjustable along the end of a freely pivoted arm 164, so that reciprocation of the head causes the oscillation of the arm. This motion is imparted'in part to a shaft 144 by means of collar 156 with projecting arms 157 and 158 carrying screws 163 adapted to be contacted by the arm 164 at the end portions its oscillating movement. Within a fluid reservoir 129, the shaft 144 carries an arm 142 which reciprocates a double-ended valve member 133 serving to close ports 131 and 132 in and also to move, hollow pistons 126, 127 within the cylinder 125. Movement of these pistons forces fluid along one of the ducts 182 or 183 into the cylinder 20 to effect the movement of the feed carriage so that the strip is fed forward during the upward movement of the punch. After the pistons 26 and 55 have moved to their limit within the cylinder 20, continued movement of the pistons 126, 127 under the action of the arm 142 forces fluid back into the reservoir 129 passed one of two spring controlled valyes 202. One end of the reservoir is closed by a spring-pressed piston which is pulled out manually by a knob 154, while the reservoir is replenished through an opening normally closed by a screw cap 208. The piston 127 is of greater cross-section than the piston 126 so that a greater volume of fluid is displaced during the feed stroke. In a modification, the pistons are of the same size, but owing to lost motion between the double ended valve member and one of the pistons, the other piston has a longer stroke.