| 摘要 |
<p>A monitoring system is disclosed for measuring and classifying the decelerating capabilities of a machine, such as a punch press. The monitoring system includes a timing circuit for measuring the elapsed time from the initiation of brake application to the stopping of the press. Means are provided to distinguish between a regular top-stop in a single stroke press cycle from an emergency stop and to shut down the press if the stopping time is excessive for the type of stop being executed. The monitoring means is provided with a self-checking system which performs dynamic self-checking at the initiation of braking, at the stopping of the press, and at the initiation of clutching. In each self-checking cycle a fault simulating signal is propagated through two independent paths or through a path which has been previously checked. The fault simulating signal will cause the press to be shut down unless it causes a control signal to change from an enabling state to a disabling state and back to the enabling state in less time than that required for the actuation of the relay means for shutting down the press.</p> |
