| 摘要 |
PROBLEM TO BE SOLVED: To provide a main shaft state detecting device for an air bearing type machine tool capable of certainly detecting a contact state of a main shaft with a housing with a simple structure, in the air bearing type machine tool. SOLUTION: A close circuit E including capacitors C1, C2 between a main shaft 11 and a housing 13 side is formed, and a resistor 551 and a coil 552 for resonance are added to the close circuit E. A resonance area is adjusted by properly adjusting the value of the resistor 551 and the coil 552, so that the detection of capacitance value can be certainly conducted by resonance, even in a condition where enough detecting ability cannot be obtained conventionally such as a case wherein the clearance between the main shaft 11 and the housing 13 is large.
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