| 摘要 |
PURPOSE:To enable excessive oil to flow around the outer periphery of an oil bearing, by forming an annular oil passage in the outer peripheral section of the bearing for supporting a spindle, and by connecting this oil passage to the intermediate section of a drain passage in series. CONSTITUTION:An oil passage 9 is formed in the inner wall of a frame 8 over the entire circumference thereof by annularly recessing the inner wall of the frame 8, being opposed to the verticall intermediate section of outer periphery of an outer race 6b. One end of the oil passage 9 is connected to the discharge port 12a of a relief valve 12, and the other end of the same is connected to the upper section of an oil tank 13 through a downstream side drain oil passage 10. The relief valve 12 is disposed in a hydraulic oil passage 14 connecting between the discharge port 4a of a hydraulic pump 4 and the introduction port of a chucking device 2 with the feed-in port 12a and supply port 12b thereof being connected to a hydraulic oil passage 14a on the hydraulic pump 4 side and a hydraulic oil passage 14b on the chucking device 2 side, respectively. this relief valve 12 discharges a part of hydraulic oil from the discharge port 12c when the hydraulic pressure in the hydraulic oil passage 14 exceeds a predetermined value. |
