| 摘要 |
The screw has a cylindrical head (3) and a threaded (1) shank (2). The periphery (31) of the screw-head (3) has two opposite-facing flat parts (32, 33) for a tool to grip, and a slot. The flat parts I32, 33) extend only for part of the head's (3) height (h) so that a part-cylindrical shoulder (34) is formed. The screw-head (3) has an inner hexagon (4) which has two opposite-facing surfaces (41, 42) parallel to which are the flat parts (32, 33). USE/ADVANTAGE - A partly cylindrical shoulder formed increases the contact surface between the screw head and tool, and reduces the danger of the workpiece being damaged by the tool used to turn the screw.
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