525 タップ立て用切りくず分断工具の開発 : めねじ強度に関する一考察(OS-8 工具・ツーリング)

概要

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In tapping, chips jammed in the tap's flute or twined around the tap cause tool breakage very frequently. In previous study, to resolve this problem, a chip-breaking tool has been developed. The chip-breaking tool forms V-grooves axially on the inner wall of hole before tapping. In tapping, the axial V-grooves make the cutting discontinuous and short chips are produced. It can obtain a good performance in tapping. However, the axial V-grooves remain in the internal thread and the thread ridge becomes discontinuous. Therefore it may reduce the strength of tapped thread. In this study, strength of threads tapped by above-mentioned method was investigated by tensile test and compared with strength of threads tapped by conventional method where the chip-breaking tool was not used. As a result, there found little difference between the tensile strengths of both type of tapped thread. That was demonstrated by considering about the various fracture mode observed in the experiments.
2006-11-24