| 摘要 |
PROBLEM TO BE SOLVED: To obtain a screw preventing screwing functions from being damaged, in the screw thin in head thickness and small in nominal diameter. SOLUTION: This screw 1 is constituted of a head part 2 forming an engagement groove 5 to which a driver bit is engaged and a leg part 4 forming a screw thread 3 integrally with this head part 2. In this case, a screw to be used for a comparatively thin product can be obtained without damaging functions because the screw 1 is a screw with thin head 1 formed into a spherical surface in which an upper surface of the head part 2 having the engagement groove 5 is formed by a large radius. Because the head parts 2 are formed into slightly spherical shapes, the head parts 2 do not closely adhere during a heat treatment and a gilding treatment work. |
