| 摘要 |
PROBLEM TO BE SOLVED: To provide a wood screw for use in screwing into a light weight soft wood such as cedar material in which a screwing-in torque is reduced and a pulling-out holding power is improved.SOLUTION: This invention relates to a wood screw in which a shank part is extended from a head part including an engagement part for a rotary tool and a screw thread is formed from a sharp end part of a shank extremity end toward the head part and this screw is screwed into a light weight soft wood such as cedar material. In regard to a pitch P of the screw thread, a groove bottom width W of the screw thread groove formed between the adjoining screw threads, an approaching side flank angle θ1 of the screw thread and a retraction side flank angle θ2, a value of W/P is set to have a range of equal to or more than 0.6 and equal to or less than 0.7, a value of θ1+θ2 is set to have a range of equal to or more than 25° and equal to or less than 40° and a relation of θ1>θ2 is set.SELECTED DRAWING: Figure 2 |
