| 摘要 |
PURPOSE:To improve a life of a hob, by forming its constitution such that a normal edge part, having a regular rack tooth profile, and a semi-staggered edge part, displacing a tooth profile in a trailing side to the inner from the rack tooth profile, are alternately arranged along a tooth trace. CONSTITUTION:This hob alternately arranges a normal edge part 16, having a regular rack tooth profile, and a semi-staggered edge part 17, displacing a tooth profile 17a in a trailing side to the inner from the rack tooth profile of the normal edge part 16, along a tooth trace 19. Accordingly, cutting is performed by the both normal edge part 16 and semi-staggered edge part 17 in a leading side while only by the normal edge part 16 in the trailing side. Consequently, the hob, which performs cutting in every other edge part in the trailing side, increases thickness of cutting chips generated by a cutting edge, reducing relieving wearing. While the hob, preventing the cutting chip from increasing its thickness in the leading side, reduces the crater wearing. In this way, a life of the hob is improved. |
