| 摘要 |
PURPOSE:To stop the operation of EDM (electric discharge machine) in response to the sensing of P wave (preliminary tremors) by connecting a relay switch, which is operated by a signal from a P wave sensor, in series with a stop switch as a part of a control circuit. CONSTITUTION:A P wave sensor 18, a normally closed switch 20 of a relay 19, a process liquid pump start switch 21, a process liquid pump stop switch 22 and a normally closed switch 24 for self-sustaining a pump contactor 23 constitute a control circuit. With this construction, when the switch 21 is depressed to start the pump and then an operation switch 25 is depressed, the contactor 27 is turned ON and is self-sustained by the self-sustaining switch 28. Operation thus commences. Two switches 23 and 27 may be turned OFF by depressing switches 22 and 26. With the switch connected in series with the switch 26, the occurrence of an earthquake will cause the switch 20 to be opened to release the self-sustension so as to stop the electric discharge machining. |
