| 摘要 |
PROBLEM TO BE SOLVED: To obtain a driving hole surely engaging an engaging groove with a driver bit in an early stage of fastening. SOLUTION: In a screw which is constituted from a head 2 and a base 3 integrally formed with this, and forms a screw-thread 5 in the base 3, a driving hole 4 is formed in a center of the head 2, furthermore plural lines of engaging grooves 10 is formed in a radial direction from the center of this driving hole 4, additionally in a surface of a hill section 20 formed between other engaging grooves 10 adjacent to this engaging groove 10, a screwing rotating direction side hill section 20 is slanted at a slant angle (θ) toward bearing surface side so that the screwing rotating direction side may become deeper. Moreover, since this slant direction faces a direction parallel to a center line of the engaging groove 10 located at a screwing direction side of the hill section 20 in the driving hole, the head is prevented from being damaged when a screw small in nominal diameter is screwed with an automatic screwing machine, and an engaging blade is surely fitted to the engaging groove at the time of fastening. COPYRIGHT: (C)2009,JPO&INPIT
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