| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a structure capable of improving a fatigue strength of a continuous part between an inner peripheral surface and an extremity end surface of a continuous cylinder 16a present at the extreme end of a base part 13a.SOLUTION: A hardening layer 23 having a hardness of Hv200 or more that is processed by induction hardening and tempering is arranged over an entire circumference of a continuous part. In addition, an axial size L of a part exposed at an inner peripheral surface of a continuous cylinder part 16a in the hardening layer 23 is set to 2 mm or more (L≥2 mm) and at the same time a difference D-d between an outer diameter size D and an inner diameter size d of a part exposed at the extreme end surface of the continuous cylinder part 16a is set to 2 mm or more (D-d≥2 mm).</p> |
