GB1146083A - Method of, and apparatus for, cold shaping sheet metal stock - Google Patents

Abstract

1,146,083. Stretch forming. CYRIL BATH CO. 8 June, 1966 [16 Dec., 1965], No. 25510/66. Headings B3E and B3Q. A method of stretch forming sheet metal over a male die 5 comprises gripping a pair of opposed margins of the stock while leaving free the remaining pair, and controlling movement of the gripped margins by respective restraining links 60, 63 to tension the stock above its elastic limit. A press for carrying out the method is similar to that described in Specification 1,029,755, except for the controlling links 60, 63 and the grippers 30, Fig. 4, which are operated, through links 33, 34, by hydraulic cylinders 36. Additional guide rolls (58, Fig. 2) are also provided for the carriages 50 carrying the grippers. At each end of the carriages 50 is pivoted one end of a link 60, 63 the other end of which may be pivoted on the lower die 5. As elevators 20 supporting the carriages are lowered by hydraulic cylinders (22, Fig. 5), the links 60, 63 move the gripper-carriages apart, thus tensioning the work, which is strained beyond its yield point before or after encountering the die 5. The tension may be maintained until the dies are closed. The hydraulic pistons 80 for moving the linkcontrolled carriages to tension the work, as described in the prior specification, may be retained, and their cylinders drained or used as shock absorbers. The die 5, carriages 50, links 60, 63 and jaw units 30 may be removed from the press as a unit. In a modification, Fig 10, the carriages are lowered by push-rods 117 on the slide 113 of a mechanical press, or described in Specification 1,010, 408. In a similar arrangement telescopic, hydraulic push rods (128, Fig. 11) are used which are connected to relief-valves. The power means for lowering the carriages may be applied to the links 60, 63.