| 摘要 |
PROBLEM TO BE SOLVED: To easily and accurately adjust weight balance about the main spindle center axis of a main spindle rotating system. SOLUTION: A main spindle device for a machine tool comprises a hollow main spindle 1 mounted with a tool on the nose, a drawbar 8 laid coaxially in the main spindle 1 for axial movement without rotation relative to the mains spindle 1 and for holding and releasing the tool on and from the nose of the main spindle 1 via axial movement, and Belleville springs 15 for urging the drawbar 8 relative to the mains spindle 2 in a direction to hold the tool. The back end of the drawbar 8 is a large-diameter portion 12 with an external surface brought into sliding contact with the internal surface of the main spindle 1. In a position a given distance spaced forward of the large-diameter portion 12, a collar 14 with an external surface brought into sliding contact with the internal surface of the main spindle 1 is fitted about the drawbar 8 for longitudinal movement without rotation relative to the drawbar 8. The large-diameter portion 12 and the collar 14 are provided with balance adjusting means for adjusting the balance of a drawbar rotating system Y.
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