| 摘要 |
PROBLEM TO BE SOLVED: To provide a loosening preventing structure for a tightening screw in which friction holding force between a male screw and a female screw of the tightening screw is maintained for strongly centering a plate tip to a holder main body even when cutting load fluctuates by change of a processing margin in a workpiece during cutting or fine vibration of a cutting edge of the plate tip or the like. SOLUTION: In this ball end mill in which a plate tip 13 is inserted into a split groove 2 crossing a tip center part of a holder main body 1, and in which the split groove 2 is closed with a tightening screw 4 to hold and fix the plate tip 13, a conical receiving surface 8 with which a head part 5 of the tightening screw 4 matches is provided on one half-split part 3, a female screw 10b of the tightening screw 4 is provided on the other half-split part 9, an abutment surface 13b in a truncated chevron shape is provided in the plate tip 13, and a receiving surface 15 for a split groove bottom part 11 is provided, thereby a trunk part 7 of the tightening screw 4 is inserted into a through-hole 13a in the plate tip 13 for fixing the plate tip 13.
|
