Molding device for manufacturng cylindrical rolling body, manufacturing method for cylindrical rolling body, manufacturing method for rolling bearing, manufacturing method for vehicle, and manufacturing method for mechanical apparatus

A manufacturing method for a cylindrical rolling body using a molding device for manufacturing a cylindrical rolling body;

• the molding device for manufacturing a cylindrical rolling body comprising a pair of molds having one side surfaces in an axial direction and arranged so as to be capable of relative displacement in the axial direction with the one side surfaces in the axial direction facing each other;
• the pair of molds having bottomed molding concave sections opening at positions on the one side surfaces in the axial direction facing each other and each having an inner surface;
• and
• the inner surface of each of the molding concave sections having an inner-circumferential surface, a bottom surface, and an annular corner R section having an arc-shaped cross section and connecting the inner-circumferential surface and the bottom surface;
• the manufacturing method comprising:
• preparing a cylindrical intermediate material having a dimension in the axial direction that is larger than and a diameter dimension that is a smaller than those of a cylindrical rolling body to be manufactured;
• inserting both side sections in the axial direction of the intermediate material inside the molding concave sections of the pair of molds respectively;
• and compressing the intermediate material by bringing the pair of molds close to each other in the axial direction and plastically deforming the intermediate material;
• to compression mold the intermediate material;
• and
• removing the both side sections in the axial direction of the intermediate material from the inside of the molding concave sections of the pair of molds in the axial direction;
• wherein at least one mold of the pair of molds has an annular concave section recessed outward in a radial direction on the inner-circumferential surface of the molding concave section;
• when compression molding the intermediate material, a part of the material of the intermediate material being made to enter into the inside of the annular concave section, forming an undercut section in a part of the outside section in the radial direction of the intermediate material;
• and
• when removing the both side sections in the axial direction of the intermediate material, the undercut section being reduced in diameter by drawing the undercut section through a stepped section existing on an end section in the axial direction of the annular concave section.