| 摘要 |
A fixing device comprises a bright zinc-plated steel shank (1) formed by cold forming with a head (2), the shank having formed thereon by thread-rolling a helical bore wall engagement configuration (6). This configuration comprises a pair of spaced apart helical ridges (7, 8) with a helical ridge (9) of larger elevation provided midway therebetween. The device readily self-taps when turned into a bore in a variety of materials. The device holds firmly in timer end grain and on continued turning of its head will perforate and embed in the timber, no amount of torquing causing the device to ream the bore when the device is penetrated into autoclaved aereated concrete. |
