| 摘要 |
<p>Forming die assembly (18,20) for carrying out a U-ing operation on a flat blank (58a) has a forming tool (80) in one (18) of two ram assemblies (18,20) which cooperates with a second forming tool (94) to perform the U-ing operation. During movement of the ram assemblies (18,20) towards each other, the forming tool (80) is retracted and remains stationary during a final portion of the stroke of the ram assembly (18) in which it is carried. The forming tool (80) is maintained in an extended position by a toggle mechanism (108) during an initial portion of the stroke and the toggle is broken during a final portion of the stroke thereby to permit the forming tool (80) to retract relative to the assembly (18). On the return stroke, the forming tool (80) is restored or shifted to its extended position by a biasing spring (150). <IMAGE></p> |
