| 摘要 |
The holder comprises a base adapted to be fixed to a part of the machine tool facing the tool holder, a work-piece backing plate rotatably carried by said base, a brake system carried by said base and by said backing plate and normally biased to a breaking position locking the backing plate against rotation in either direction. The backing plate has a hole through which a pin can be inserted, the pin causing release of the brake , so that the pin can rotate the backing plate to another indexed position. Upon withdrawal of the pin from the hole, the brake automatically blocks backing plate rotation. By fixing the pin to the tool holder of a numerically-controlled machine tool, the latter is converted into a machine tool with an additional axis of movement, namely indexing rotation of the backing plate under the control of the tool holder.
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