| 摘要 |
PROBLEM TO BE SOLVED: To provide a detent tapping screw repeatedly usable by low screwing torque. SOLUTION: In this tapping screw 1 comprising a head part 2 and a leg part 4 integral with the head part 2 to have a thread ridge 10, a plurality of states of clearance grooves 20 crossing at an angle α smaller than 90 deg. relating to a lead line of the thread ridge 10 to tilt in a reverse direction to the lead line are formed, a width of the clearance groove 20 is formed narrow in a head part side and wide in a leg part side, and a bottom surface 23 positioned in parallel to the bottom of the leg part 4 between forward/backward side slopes 21, 22 in a screwing direction of the clearance groove 20 also with a depth at most 70% a thread ridge height from a thread ridge external diameter line is formed, the self locking tapping screw is alternately formed with the thread ridge 10 and the clearance groove 20, when axial force is applied to the screw, a sagging part can be formed by turning round resin material in the periphery of an edge part in a pressure side flank surface of the thread ridge in the clearance groove, rotation in a return direction can be impeded. A sufficient detent effect can be obtain by advancing a little in the clearance groove of the resin material, even when it is relatively hard. |
