METHOD AND APPARATUS FOR HEAT TREATING HOLLOW SHAFT, AND SCREW SHAFT

摘要

PROBLEM TO BE SOLVED: To solve the problem that hardening with high accuracy is difficult since a coolant does not smoothly flow into a hollow hole when induction hardening is performed from the outer peripheral surface of a hollow shaft while permeating water to the hollow hole of the hollow shaft. ! SOLUTION: A method for heat treating a hollow shaft comprises: arranging a hollow shaft 12 between a cusp part 13 of a lower end support jig 2 and a cusp part 15 of an upper end support jig 3; and relatively moving the hollow shaft 12 to an induction heating coil 5 and a cooling jacket 6 while a coolant flowing dowm a hollow hole 12a to perform induction hardening. The coolant is diffused toward the peripheral wall surface of the hollow hole from a trumpet-like injection hole 19 of the upper end cusp part 15, flows along the peripheral wall surface of the hollow hole and is quickly discharged to the outside of the lower end cusp part 13 from a discharge part 14 consisting of a half center. ! COPYRIGHT: (C)2