| 摘要 |
PROBLEM TO BE SOLVED: To accurately obtain a desirable screw fastening torque with excellent galling property in relation to a drive hole without generating a slip out of a driver bit. SOLUTION: The drive hole 10is formed of an engaging groove 11 and a fitting part. A side wall, with which the driver bit 20 is to be engaged when screwing, is formed as a vertical driven surface 13 vertical to a surface horizontally crossing an axis of a screw 1, and an opposite side is inclined to be formed as an inclined driven surface 14. On the other hand, both side walls adjacent to each other are connected to each other by a fitting surface 15, and a base part of the driver bit 20 is brought in contact with the fitting surface 15. With this structure, a large thrust for obtaining a large fastening torque is unnecessary, and especially, torque control in an automatic assembling work line is facilitated, and unevenness of the screw fastening torque is eliminated to reduce the generation of failure products. Galling is generated between the fitting hole and a tip of the driver bit by the straight-sided fitting surface of the drive hole, and the center of rotation is always fixed to stabilize screw fastening work. COPYRIGHT: (C)2004,JPO
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