| 摘要 |
PROBLEM TO BE SOLVED: To ensure safety in a main spindle device by detecting a mistake in clamping or an abnormal clamping state when a tool is clamped. SOLUTION: The main spindle device clamps a toolholder 9 with a collet chuck 8 when a Belleville spring 7 inserted in a spindle hole 5 draws a drawbar 6, and unclamps the toolholder 9 when an unclamping cylinder 11 pushes the drawbar 6 against the Belleville spring 7, and comprises an unclamping verification switch 19 switched on and off by reciprocation of the unclamping cylinder 11, and a spindle-rotating-drive start command switch 20 for driving or rotating a main spindle 2 at the receding end of the unclamping cylinder 11. A clamping mistake detection switch 21 is arranged so as to be switched on upon a mistake in the clamping of the toolholder 9, and a restriction 28 is arranged in a fluid pressure discharge passage working in a receding operation of the unclamping cylinder so as to cause the receding movement of the unclamping cylinder 11 to follow the drawing movement of the drawbar 6.
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