| 摘要 |
PROBLEM TO BE SOLVED: To provide a wood screw capable of reducing screwing torque even when screwing in hard wood. SOLUTION: This wood screw is composed of a shaft element 2 having a pointed tip end 2a at one end and head portion 3 at the other end, and a spiral screw thread 4 formed on outer peripheral surface of the shaft element 2. The pitch of a spiral screw thread 4a at the tip end portion is made to be different from the pitch of the other portion. When screwing in a wood material, a spiral groove formed by the screw thread 4a of the tip end portion is broken with the following screw thread, which produces an effect like as boring a prepared hole by a drill, so that the wood screw can be screwed in by light torque. |
