LOOSENING PREVENTING FASTENING MEMBER AND LOOSENING PREVENTING BOLT

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a loosening preventing bolt, by which a loosening preventing bolt having a tapered cylindrical portion the diameter of which gradually increases from the head of a bolt and concentric to the axis of the bolt, can be more rationally produced.;SOLUTION: The bolt includes a tapered cylindrical portion 12 integrally disposed continuing from a bolt head 11 and surrounding the shaft 21 of the bolt in such a manner that the diameter of the tapered cylindrical portion gradually increases concentrically with the shaft 21 of the bolt and that the end face of the portion functions as a seat face 13 to be in contact with an object to be fastened. The inner circumferential face 12a of the tapered cylindrical portion is formed into a conical curved face and the outer circumferential face 12b of the tapered cylindrical portion is formed into a recessed curved face. A shaft member 20 constituting the shaft 21 of the bolt, and a head member 10 constituted of the bolt head 11 and the tapered cylindrical portion 12 are formed as separated components. Then the shaft member 20 and the head member 10 are joined by friction welding, and the pressure-welded portion 16 by the friction welding is subjected to an annealing treatment.;COPYRIGHT: (C)2012,JPO&INPIT