Abstract: In a manufacturing process of a corrugated cage, an intermediate assembly 17a is configured by press-fitting each of press-fitting portions 24 and 24 respectively provided in base end portions of rod portions 13b and 13b of rivets 9b and 9b into each of through-holes 12a and 12a of a cage element 8a on one side, and nitriding treatment is performed on the intermediate assembly 17a. An axial dimension X of each of the press-fitting portions 24 and 24 is made smaller than an axial dimension Y of each of the through-holes 12a and 12a (X<Y). In this way, portions which do not come into close contact with each other are provided in axial portions of the inner peripheral surface of each of the through-holes 12a and 12a and the outer peripheral surface of each of the rod portions 13b and 13b, and thus a nitrided layer is formed on each of these portions which do not come into close contact with each other.

Abstract: In a manufacturing process of a corrugated cage, an intermediate assembly 17a is configured by press-fitting each of press-fitting portions 24 and 24 respectively provided in base end portions of rod portions 13b and 13b of rivets 9b and 9b into each of through-holes 12a and 12a of a cage element 8a on one side, and nitriding treatment is performed on the intermediate assembly 17a. An axial dimension X of each of the press-fitting portions 24 and 24 is made smaller than an axial dimension Y of each of the through-holes 12a and 12a (X<Y). In this way, portions which do not come into close contact with each other are provided in axial portions of the inner peripheral surface of each of the through-holes 12a and 12a and the outer peripheral surface of each of the rod portions 13b and 13b, and thus a nitrided layer is formed on each of these portions which do not come into close contact with each other.