| 摘要 |
A stretch assembly or fixture for tensioning sheet metal stock in conjunction with draw forming. The stretch assembly supports the lower or bottom die member and has two upright stretch units, one on each of two opposite sides of the die. Each unit includes a work gripping head movable vertically relative to frame structure of the unit. A jaw assembly of each head is adapted to engage one of two opposite edges of a metal sheet to be formed and is movable relative to its head transversely of the vertical path of the head travel to stretch the sheet. Stretch links are pivotally connected between each jaw assembly and the frame structure of the respective stretch unit and move the jaw assemblies in a prescribed path transversely of the path of head travel in response to vertical movement of the gripping heads. The vertical position at which the links are pivoted on the stretch unit frame structure and the effective length of the links can be adjusted to control the movement of the gripping heads. The jaw assemblies include upper and lower jaw members. The upper members are supported for vertical movement to grip and release work and horizontal movement to expose the lower jaw to facilitate loading on extracting work.
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