Patent GB-759533-A (GB)
Title: Means for feeding work pieces to a cutting or shaping press
IPC: B21D43/10
Filed: 1954-02-16
Abstract: 759,533. Feeding mechanism for stamping &c. presses. UDAL, J. D., and DAVIS, S. Feb. 14, 1955 [Feb. 16, 1954], No. 4494/54. Class 83 (4). In apparatus for feeding workpieces to a stationary tool of a press, comprising a pneumatically-operable gripper, or a sucker pad, on a carrier which moves the gripper &c. through a substantially horizontal path to a position above the tool and then lowers the gripper &c. to deposit a workpiece on the tool, an air-release valve is operable by the carrier during the completion of the downward movement of the gripper &c. If, however, the previous workpiece has not been removed from the stationary tool, the gripper cannot complete its downward movement, the air-release valve is not operated, and the gripper returns without releasing the new workpiece. The apparatus shown is substantially as described in Specification 738,878, the gripper carrier comprising a pair of parallel links 4, 5 pivotally connected to an arcuate link 6 at their lower ends. The upper end of the link 5 is adjustably secured to a spindle 10 which is oscillated by crank, link, and lever means 24, 25, 26 from a power shaft 23, and the upper end of the link 4 is freely mounted on a spindle 7, both spindles being mounted in fixed brackets 8. The spindle 7 is driven by chain-and-sprocket means from the shaft 23. Compression springs 27 in the link 25 allow a dwell between successive movements of the carrier 4, 5. The link 4 is extensible and comprises two relatively slidable parts 4a, 4b interconnected by a compression spring 12 arranged between abutments on the respective parts. A cam 11 secured to the spindle 7 operates on a roller 13 on the part 4a to vary the effective length of the link 4 and impart pivotal movement to the arcuate link 6 about the link 5. The gripper comprises two jaws 14 on pivoted blocks 15, and extension arms 17 on the blocks 15 are adapted to be urged apart, to open the jaws 14, by a wedge 18 which acts against the action of a spring 19. The wedge 18 is connected to a piston 21 in a cylinder connected to a source of compressed air by a pipe 37 leading to a valve 32 controlled by a cam on the spindle 7. Arranged between the valve 32 and the gripper are a non-return valve 38 and an air-release valve 39, the latter being mounted on the link part 4a and operable, through an arm 40 on the link part 4a by an adjustable abutment 41 on the part 4b to release compressed air during completion of the downward movement of the gripper for depositing a workpiece on the stationary tool 36 of the press. In operation, the gripper carrier is swung inwardly beneath the rising tool 42, the cam 11 then permits shortening of the link 4 by the spring 12, thus causing the link 6 to pivot about the link 5 and lower the gripper which deposits the workpiece on the stationary tool 36. If the downward movement of the gripper with the workpiece is obstructed, say by a treated workpiece not properly ejected from the tool 36, the air-release valve 39 is not opened, and the untreated workpiece is retained by the jaws 14 during the ensuing movements of the carrier until the treated workpiece has been removed from the tool 36. Workpieces may be fed from a table 35 which is rotated intermittently by pneumatic mechanism controlled by a valve actuated by a cam on the spindle 7. In a modification, the gripper carrier may oscillate in a horizontal path about a vertical axis, and lowered by oscillating about a horizontal axis, and the carrier may be spring-pressed against a cam track. The air-release valve could be associated with the cam track and actuated by the carrier. Also, the pneumatically-operated gripper may be replaced by a suction pad.