| 摘要 |
PROBLEM TO BE SOLVED: To provide a looseness preventive bolt that can be produced further rationally.SOLUTION: A looseness preventive bolt 100 is provided with a taper cylindrical body part 12 that surrounds a bolt shaft 21 integrally from a bolt head 11, has a gradually expanding diameter concentrically with the bolt shaft 21 and has an end surface serving as a bearing surface 13 in contact with a fastened body 40. A shaft member 20 is formed as a part separately from a head member 10 that has a convex part 15a projecting in a short columnar shape in an inner bottom part 15 of the bolt head 11 and is formed to accommodate segregation 23 of a pressure welding part between an outer circumferential surface 15b of the convex part and an inner circumferential surface 12b of the taper cylindrical body part 12. The shaft member 20 and the head member 10 are joined by friction pressure welding and an annealing treatment is applied to the pressure welding part created by the friction pressure welding. |
