| 摘要 |
In the operation of punching a performed stop blank onto a pair of coupled fastener stringers placed over a stationary die, a sensor is provided which moves up and down over the die to sense mechanically the presence of any foreign matter such as the operator's fingers between the punch and die. The punch is permitted to descend fully onto the stringers on the die only after the sensor has completed its downward stroke. In the apparatus of the invention the up-and-down motion of the punch is effected as by an air cylinder via a lever, and the sensor is coupled to another lever which is spring loaded to follow the motion of the punch lever, in such a manner that the sensor travels faster than the punch. Limit switches are employed to prevent the full descent of the punch where necessary. |
