| 摘要 |
A workpiece engaging apparatus includes a drive having a linearly reciprocal drive member. Two pairs of arms are arranged in opposed, inverted relationship with respect to each other and are pivotally connected at one end to the drive. Each arm has a cam formed therein. The cams in each of the pairs of arms are identically constructed, but the cams in one pair are disposed in opposed, inverted relationship with respect to the cams in the opposed pair of arms. Cam follower members mounted on the linear drive member engage the cams during reciprocal movement of the drive member to pivot the pairs of arms between an open, spaced-apart position and a closed workpiece engaging position. Each of the cams includes a first arcuate shaped first end portion which smoothly merges into a substantially linear second end portion. The arcuate shaped first end portion is disposed at a generally obtuse angle with respect to the pivot pin connecting each of the pairs of arms to the drive to provide smooth, non-locking pivotal movement of the arms as the linear drive member moves from the first end of the cams. |
