| 摘要 |
1466906 Screw heads RESEARCH ENG & MFG Inc 25 Oct 1974 [7 Dec 1973] 46173/74 Headings F2H and F2U [Also in Division B3] A fastener head and corresponding socket wrench 32 have a shape defined by flat surfaces 18 which lie in planes forming a hexagon centred on the axis 10, surfaces 20 in planes 22, and surfaces 24 in planes 26. The planes 22, 26 contain the axis 10 and are preferably spaced at equal angles 28. Surfaces 20, 24 constitute force-receiving walls for threading or unthreading the fastener, while the surfaces 18 allow engagement by a conventional hexagonal wrench. A fastener may have a recessed head or end of equivalent geometrical form for engagement with a torque-tool. A die for forming the head of a fastener constitutes another embodiment of the invention.
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