| 摘要 |
PROBLEM TO BE SOLVED: To lower a lifting range of a main shaft head and to allow high speed lifting of a driven saddle and the main shaft head with a pole screw driving device, by mounting the pole screw to a main shaft head support portion for supporting the main shaft head of the saddle. SOLUTION: A pole screw driving device 3 is stood on a main shaft head support portion 6 on the left side in the X-axis direction for a main shaft head 2, and has a pole screw 10 fixed to the main shaft head support portion 6. Since the pole screw 10 is fixed to the main shaft head support portion 6 of a saddle 1, the saddle 1 does not require a connecting portion. Therefore, the saddle is lighted, and the saddle 1 and the main shaft head 2 driven by the pole screw driving device 3 can be lifted up and down. A height H2 of a column 4 can be lowered by the height of a connecting portion when the saddle 1 is lifted up and down in a certain range.
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