| 摘要 |
PROBLEM TO BE SOLVED: To provide a main spindle of an NC lathe capable of holding various kinds of chucks such as an opening fixture, a closing fixture, a chuck of a work sandwich clamp type, etc., free to automatically connect and disconnect. SOLUTION: This main spindle 1 of an NC lathe is held inside of a main spindle base HS free to rotate through a plural number of bearings 2. A shaft center inside of the main spindle 1 is furnished with a draw bar 6 for work clamping to hold a plug 5 to clamp a work 3 by a chuck (opening fixture) 4 on its head end part free to connect and disconnect and a cylinder 7 for work clamping to advance and retreat in the axial direction by connecting a cylinder piston 8 to a rear end of the draw bar 6 for work clamping. Additionally, the main spindle 1 is furnished with a draw bar 9 for chuck clamping provided in a concentrical tubular state by externally surrounding the draw bar 6 for work clamping and to hold the chuck (opening fixture) 4 on its head end part free to connect and disconnect and a cylinder 10 for chuck clamping to advance and retreat in the axial direction by connecting its cylinder piston 11 to a rear end of the draw bar 9 for chuck clamping.
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