| 摘要 |
A fixing device including a shank and a head. The shank has formed thereon a helical thread configuration including a pair of spaced helical ridges with a helical groove defined therebetween. The height of the ridges is reduced at both ends of the shank with their height gradually increasing over one convolution from an end opposite the head, and decreasing over half a convolution to an end nearest the head. |
