| 摘要 |
PROBLEM TO BE SOLVED: To provide a wood screw including with a protrusion capable of preventing over-screwing without damaging a member.SOLUTION: A rear surface of a head part of a wood screw is provided with a protrusion protruded in a protruding direction of a screw shaft, one or two or more protrusions are arranged over an entire region or a partial location of a lateral width between an outer periphery of the screw shaft to the outer peripheral surface of the head part, and a height of the extremity end of the protrusion is a height becoming a contact resistance of size that a worker rotating and operating a drill can sense when a screwing of the wood screw advances and contacts with wood. The protrusions can be arranged at one or two or more circumferences in a lateral width from the outer periphery of the screw shaft at the rear surface of the head part to the outer peripheral surface of the head part. The height of the protrusion can be made same from the extremity end of the protrusion to the rear end of the protrusion or gradually increased or decreased from the extremity end of the protrusion, or increased in a stepwise manner. It is possible to make the extremity end of the protrusion in flat shape or circular arc or acute. It is possible to make a width from the extremity end of the protrusion to the rear end of the protrusion wide or narrow gradually.SELECTED DRAWING: Figure 1 |
