| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotary shaft apparatus capable of accurately determining whether a tool is normally held with respect to a main spindle, and also to provide a method for determining the holding condition of the tool in the rotary shaft apparatus. SOLUTION: A rod 15 removable in an axial direction is formed in the main spindle 12 of the rotary shaft apparatus 1. The rod 15 is energized backward to the main spindle 12 by a plate spring 16. The rod 15 grips a tool T at its front end, retreats in the main spindle 12, and holds the tool T at the front end of the main spindle 12. A tapered surface 152a is formed at the rear end of the rod 15, and a displacement sensor 181 is arranged oppositely to the tapered surface 152a. An abnormality determining apparatus 18 including the displacement sensor 181 calculates an acceleration when the rod 15 retreats, based on a distance with the tapered surface 152a, detected by the displacement sensor 181, and determines that the tool T is not normally held by the main spindle 12 in the case where the maximum value of the acceleration does not exceed a predetermined value. COPYRIGHT: (C)2010,JPO&INPIT
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