| 摘要 |
PROBLEM TO BE SOLVED: To perform precise high speed machining by providing a tool mounting hole formed in the tip part of a main spindle to mount a tool, and a main spindle heating and cooling means for heating and cooling the periphery of the tool mount hole of the main spindle to enlarge and reduce the tool mount hole, thereby removably holding the tool in the tool mount hole. SOLUTION: This main spindle device 11 for a machine tool includes a spindle 15 rotatably supported in a main spindle housing 13, and a tool mount hole 15a is formed in the tip part of the spindle 15. At this time, in the main spindle housing 13, a heating coil 17 for heating and cooling a clamp part to enlarge and reduce the tool mount hole 15a and a cooling fluid passage 19 are provided in a region confronting with the clamp part of the spindle 15. The heating coil 17 is buried in the spindle housing 13, and connected to a power supply device. The cooling fluid passage 19 has a cooling fluid inlet part 19b and plural cooling fluid outlet ports 19c confronting with the clamp part of the spindle 15, and air is supplied as a cooling fluid from a cooling fluid supply source 19a.
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