| 摘要 |
A screw usable as either a wood screw or a self-tapping screw comprises a two start helical thread (12) having a helix angle of 20<o> or more with an included angle to the thread profile at its crest of 40<o> or less. The threads are raised rapidly from a conical un-threaded entry point (14) and the thread crest diameter is greater than that of the unthreaded shank portion (10) of the screw. |
