| 摘要 |
The screw-in torque of a self-tapping screw is minimised by the screw having a cylindrical shank portion 3, a conical portion 4 leading in to the shank portion, and a thread 7 on the shank and the conical portion. The conical portion 4 has a plurality of first conical sub-portions (4') having a first cone angle uniformly distributed about the circumference of the fastener and a plurality of second conical sub-portions (4") with a second cone angle smaller than the first cone angle and arranged between the first conical sub-portions (4'). <IMAGE> |
