| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a main spindle device of a machine tool improving processing accuracy. Ž<P>SOLUTION: A main spindle 1 of the main spindle device is supported in the radial direction by a rotary bearing 2, and journaled in the rotary shaft C direction by a thrust bearing pad 3. A fluid pipe 31 extending upward and downward is formed on the thrust bearing pad 3, and air pressure supplied from an introduction pipeline 62 of an introduction part 61 is injected to a bottom face of the main spindle 1 via the fluid pipe 31. An injection path 37 branched from the fluid pipe 31 is opened at an upper end of a piezoelectric actuator 5 mounted to a bottom end of the thrust bearing pad 3, and a relief valve 4 is provided between the fluid pipe 31 and the injection path 37. The relief valve 4 is closed when the air pressure in the fluid pipe 31 is not more than a predetermined value, and opened when the air pressure in the fluid pipeline 31 exceeds a predetermined value. Then, the air pressure is directly injected to the piezoelectric actuator 5 via the injection path 37, to cool the piezoelectric actuator 5. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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