| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw with a screw head having a rotation moment transmitting means, having high resistance when the head is broken off from a shaft. SOLUTION: The screw 10 comprises a thread 15 formed at least in part, and the shaft 11 for defining an axial line A. The shaft 11 has a tip 13 at one end and the head 14 at the other end on a side opposite to the side of the tip 13. A transition portion 12 is formed between the head 14 and the shaft 11. On the transition portion 12, three to ten truncated cone shaped portions 21, 22, 23 are formed continuously over a wide range in the axial direction. Generating lines of the truncated cone shaped portions 21, 22, 23 has different angles of inclinationsα,β,γwith respect to the axial line A. These angles of inclinationsα,β,γare gradually smaller following transition from the head 14 to the tip 13, but the first angle of inclinationαof the generating line of the first truncated cone shaped portion 21 at a position nearest the head is 40-50°. COPYRIGHT: (C)2009,JPO&INPIT
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