| 摘要 |
<p>A device for shifting a workpiece on a nibbling machine which includes a rotary eccentric shaft which is rotatable to move a nibbling punch into and out of association with a workpiece, comprises a workpiece holder which is driven by a first motor in one direction, and a second motor in a direction transverse to this direction. A switch control is connected to each motor and includes means for imparting a programmed control of the operation of the motors which is varied in accordance with a sensing of the thickness of the workpiece being operated upon so that the movement may be accomplished when the nibbling punch is not in contact with the workpiece. The apparatus includes a control switch in the form of a switch lug which is mounted for rotation with the eccentric shaft of the nibbling punch and which cooperates with a contactless switch member to cause a turning on and off thereof. The control switch lug is advantageously contoured so that it defines an inner switch control surface which defines a control arc of operation which is greater than an outer surface, and means are provided for shifting the responsive switch so that it cooperates selectively with either the inner or outer surface or an intermediate surface in accordance with the thickness of the plate being formed.</p> |
