| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw member having sufficient strength even when rotationally driven and screwed in use with an electric power tool. SOLUTION: The screw member includes a prepared hole formed in the iron wall face, and a tapping screw part to be inserted into the prepared hole in a tapping manner. The tapping screw part is formed of carbon steel of 0.18-0.26% carbon containing iron, which has a total length of 5-15 mm, an outer diameter of 5-15 mm not including a thread, a thread height of 0.6-1.0 mm, and a maximum thread width of 0.2-0.4 mm, and whose thread has an approximately triangular cross section, a peak angle of 20-45°, and a pitch of 1-2 mm. It is subjected to surface quenching. A hardened layer is provided ranging 0.4 mm from the surface of the tapping screw part not including the thread, with its hardness twice or more that of the center. COPYRIGHT: (C)2009,JPO&INPIT
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