Patent GB-1389721-A (GB)
Title: Workpiece transfer mechanisms
IPC: B21D43/05
Filed: 1972-03-07
Abstract: 1389721 Workpiece feeds B J WALLIS 7 March 1972 [8 March 1971] 10560/72 Heading B3W A workpiece transfer device for a press comprises a work-engaging finger bar 30, reciprocable relative to a carriage 24 in opposite directions transverse to the workpiece feed direction in which the carriage is reciprocable, an axially reciprocable rod 74 passing through the carriage, a shaft 142 journalled in the carriage and operatively connected to the finger bar for reciprocating it in said opposite directions on rotation of the shaft in opposite directions, a cam 126 and a cam follower 124 operatively connecting the rod and the shaft so that axial movement of the rod relative to the carriage in opposite directions causes rotation of the shaft in opposite directions and means 75, 75<SP>1</SP> operatively connecting the rod and the carriage for reciprocating the carriage during selected portions of the axial reciprocation of the rod. The transfer device is operated by a vertical shaft 39, which is reciprocated by the press ram and is connected through racks, gearing and an overload disconnection device 46 with the rod 74. The cam follower 124 is pinned to the rod 74 and engages in the helical cam slot 126 in a sleeve 128, surrounding the rod and journalled in the carriage, and a straight slot 130 in a plate fixed to the carriage, the slot 130 ensuring that reciprocation of the rod causes the sleeve 128 to rotate. A pinion 138 fixed to the sleeve 128 meshes with a pinion 140 on a hollow shaft 142 which is also journalled in the carriage. An overload disconnection device between the pinion 140 and the shaft 142 comprises balls (148), Fig. 3 (not shown), unseated from chamfered seats (150) when a predetermined torque, adjustable by means of spring (154), is exceeded. A pinion 160 on the shaft 142 meshes with a rack portion on a rod 32 connected to the finger bar 30. Passing through the shaft 142 and coupled to it by rollers (164), Fig. 3, is a square section shaft 166. The shaft 166 is similarly coupled to a hollw shaft 170 which carries a pinion 178 meshing with a rack portion on a finger bar-supporting rod 34, rotation of pinion 140 causing simultaneous movement of rods 32 and 34. The shaft 166 remains fixed relative to the base 20 whilst the carriage is reciprocated. The carriage 24 has indentical latches 75, 75<SP>1</SP> at the front and rear respectively, the latch 75 coupling the carriage to the base 20 during inward movement of the finger bar and to the rod 74 for longitudinal feed movement of the carriage and the latch 75<SP>1</SP> operating similarly for the return movements of the finger bar and carriage. The latch 75 comprises a gate 80 and a latch 78 on a common pivot 81 on the carriage, both spring biased in a clockwise direction, Fig. 4, to rest positions in which a face 84 on the latch 78 abuts a stop 104, and a notch 94 in the gate rests on a pin 102, on the carriage. In these positions, the centre of a hole 90 through the gate is eccentric relative to the axis of the rod 74 which also passes through a hole 99 in a wear plate 97 fixed to the carriage. The carriage is coupled to the base Fig. 2 when the gate 80 engages behind the right hand shoulder 108 of a stop 106 on the base and to the rod 74 when a face 82 on the latch 78 engages a notch 120 in a bush 114 fixed to the rod. Bushes 114, 114<SP>1</SP> are released by cams 122, 122<SP>1</SP>. Fig. 1 shows the finger bar 30 in retracted position and the carriage 24 in the return position. In operation, upward movement of the shaft 39 with the press ram moves the rod 74 to the left (Figs. 1 and 2), the gate 80 coupling the carriage to the base. The cam follower 124 causes the sleeve 128 and shaft 142 to rotate and advance the finger bar, in direction a, Fig. 1. The cam slot 126 preferably includes a portion 127 which extends parallel to the axis of the sleeve 128 and which the cam follower engages while the finger bar is in the work-gripping position. When bush 114 reaches the latch 75 its chamfered leading edge 118 rotates the latch 78 and gate 80 counter clockwise and when its front face engages the wear plate 97, the latch 78 is urged by its biasing spring into the notch 120 to couple the carriage to the rod and the gate is disengaged from shoulder 108 to uncouple the carriage from the base. The carriage is advanced in direction b by the rod and at the end of its feed stroke the gate 80<SP>1</SP> of latch 75<SP>1</SP> engages the left hand shoulder 108<SP>1</SP> of stop 106<SP>1</SP> (Fig. 2) to couple the carriage to the base. Just before the end of the feed stroke the cam 122 releases the latch 78 from the bush 114 to uncouple the carriage from the rod. On the downward stroke of the press ram the rod moves to the right (Figs. 1 and 2), causing the finger bar and the carriage to move 1 in directions c and d respectively, to return to the Fig. 1 position, in a similar fashion to their movement in directions a and b respectively but in reverse. A safety retraction device 182, Fig. 1, retracts the finger bar if operation of one of the overload disconnection devices have left the bar in the path of the descending press tool. A bar (194), (Fig. 7, not shown), on the press ram strikes a roller 188 on a crank arm 186, if the bar is not retracted, which through gears 190, 192 and shaft 184 rotates the shaft 166 to retract the bar. In an alternative embodiment, Fig. 11 and 12 (not shown) a finger bar (30<SP>1</SP>) is operated in unison with the bar 30. The drive and safety retraction device are located between the finger bar-supporting rods. In both embodiments the stroke of the finger bar(s) may be changed by changing the sleeve 128 for one with a different cam slot and that of the carriage by moving the bushes 114, 114<SP>1</SP> and the stops 106, 106<SP>1</SP>.