| 摘要 |
PURPOSE:To enhance the safety of a machine tool having a spindle comprising a ceramic material by fitting a supersonic transducer to the spindle and stopping or reducing the rotation of the spindle quickly at the occurrence of a crack and the like. CONSTITUTION:A spindle 1 is fitted with a transducer 7 capable of transmitting and receiving a supersonic wave, a control device 8 sends a transmission signal thereto and the transducer 7 is made to generate a supersonic wave for the transmission thereof to the spindle 1. Then, said supersonic wave repeating reflections in a ceramic body comprising the spindle 1 is again received by the transducer 7 and fed back to the control device 8 as a detecting signal. If a crack has occurred on the spindle 1 in this case, comparison is made with a reference signal from a reference pattern generator 9 and a control signal is generated from the control device 8. As a result, a drive source 5 works to stop the rotation of the spindle 1 or increase the rotary speed thereof.
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