| 摘要 |
PCT No. PCT/HU93/00019 Sec. 371 Date Aug. 10, 1995 Sec. 102(e) Date Aug. 10, 1995 PCT Filed Mar. 31, 1993 PCT Pub. No. WO94/17946 PCT Pub. Date Aug. 18, 1994A thread tapping cutting tool includes a working part with a chamfer portion, control portion, and at least two thread cutting wings (separated by flutes) formed therein. The chamfer portion is at least one half of the length of the working part. Each of the two or more thread cutting wings has a width of not more than 0.2 times a tap drill outer diameter of the working part, and not less than 0.02 times the tap drill outer diameter. The chamfer portion has plane surface lands on the cutting wings at the outer edge, and a relief angle of the plane surface lands is greater than 5 degrees. The core diameter of the cutting wings is defined by the depth of the flutes, and is not more than 0.35 times the tap drill outer diameter. |
