| 摘要 |
<p>A screw member capable of being reduced in size and weight. A pair of side wall surfaces (18) of each of six torque transmitting parts (16) lie on lines passing through the center line(O) in a sectional shape perpendicular to the center line (O) so as to transmit torque via the side wall surfaces (18), whereby the direction of a surface orthogonal force N applied from a screw tightening tool agrees with the direction of a tightening-effectuating tightening force F at a point of force application Q to which a tightening torque is transmitted. The above arrangement reduces a turning operation force applied to the screw tightening tool and a load acting on a torque transmitting part (16) in comparison with a conventional hexagonal head (100), and decreases the diameter of the head (12) of the screw member (10) to reduce the size and weight thereof while avoiding the crash or the like of a torque-transmitting side wall surface (18).</p> |
