| 摘要 |
PROBLEM TO BE SOLVED: To reduce a quadrant switch-over step by suppressing a pressure fluctuation when a quadrant of a moving object is switched over, in a simple structure. SOLUTION: The pressure fluctuation adjusting apparatus 25 of a machine tool 1 is provided with: a hydraulic cylinder 8 for reducing a weight load of a spindle head 4 by drawing it up; a hydraulic unit 14 for supplying a hydraulic pressure to the hydraulic cylinder 8 from a hydraulic pump 12 through an oil feed flow path 15; and a relief pressure reduction valve 17 arranged between the hydraulic unit 14 and the hydraulic cylinder 8, for reducing a pressure in the hydraulic cylinder 8. An accumulator 20 is equipped in the oil feed flow path 15 between the relief pressure reduction valve 17 and the hydraulic cylinder 8. An impact pressure which pressurizes pressure accumulation oil in the hydraulic cylinder 8 when a quadrant is switched over from an ascending movement to a descending movement in a vertical plane of the spindle head 4, is absorbed by the accumulator 20, and then since the impact pressure is released to a hydraulic tank 13 by the relief pressure reduction valve 17, it is reduced and adjusted into a normal operation pressure. COPYRIGHT: (C)2010,JPO&INPIT
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