| 摘要 |
PROBLEM TO BE SOLVED: To solve by providing on surface of a male thread or/and surface of at least female thread a surface soft coating portion of which hardness is lower than that of a matrix because there is limitation to improve fatigue strength of an engaging part of the male thread with the female thread with a conventional thread fastening member. SOLUTION: The thread fastening member provides on either at least of the surface of the male thread 10 or the surface of the female thread 20 the surface soft coating portion 21 of which hardness is lower than that of the matrix. As a result, it can restrain occurrence of eccentric contact and local high stress in the engaging part at which the male thread 10 of a bolt 1 and the female thread 20 of a nut 2 engage with each other. Thereby, since the thread fastening member can improve the fatigue strength of the engaging part of the male thread 10 of the bolt 1 with the female thread 20 of the nut 2, it is effective to be used in such a portion that repeated stress occurs on the engaging part of the male thread 10 of the bolt 1 with the female thread 20 of the nut 2. COPYRIGHT: (C)2007,JPO&INPIT
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