| 摘要 |
PROBLEM TO BE SOLVED: To provide a tapping screw having superior biting property to a prepared hole even when thrust force in screwing work is reduced, and to easily correct inclination of a screw in an initial period of screwing. SOLUTION: In this tapping screw composed of a head portion 2 and a leg portion 3 integrated with the head portion in a state that a thread 10 of the leg portion 3 has an ordinary thread portion 11 of the uniform thread shape from a tip to a head portion side, a guide thread portion 12 of a diameter smaller than the ordinary thread portion 11 is formed on the tip of the leg portion 3, a female screw forming portion 13 of a diameter larger than the ordinary screw portion 11 is formed between the guide thread portion 12 and the ordinary thread portion 11, and further they are connected so that the diameter of the thread is gradually increased from the guide thread portion 13 to the female screw forming portion 13, thus the screw bites without cutting a workpiece in starting the screwing. Further as the diameter of the thread is gradually increased from the tip of the leg portion to the female screw forming portion, the inclination of the tapping screw can be corrected even when it is inclined a little in the initial period of screwing, and a floating phenomenon of the screw can be solved. COPYRIGHT: (C)2007,JPO&INPIT
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