A near-net shape forming method for fabricating the precise bearing ring forging is invented. The processing method is composed of following three procedures. (1) the precise ring-like billet with chamfer angle is manufactured by the machining method. (2) The billet is heated by the less oxidation or non-oxidation heating method before ring rolling. (3) The bearing ring forging integrating with the raceway is formed in one pass of the rolling process by the ring rolling method.

A near-net shape forming method for fabricating the precise bearing ring forging is invented. The processing method is composed of following three procedures. (1) the precise ring-like billet with chamfer angle is manufactured by the machining method. (2) The billet is heated by the less oxidation or non-oxidation heating method before ring rolling. (3) The bearing ring forging integrating with the raceway is formed in one pass of the rolling process by the ring rolling method.

Construction is achieved that, together with preventing the occurrence of damage to a mandrel, is able to improve precision of the shape of a ring-shaped member after processing. A mandrel includes a pair of support shaft sections that are provided so as to be separated in the axial direction and so as to be concentric with each other, and a rolling shaft section that is concentrically provided in the axial direction between the pair of support shaft sections. One of the support shaft sections is provided in a state in which displacement in the axial direction with respect to the rolling shaft section is regulated. The other support shaft section is provided in a state in which displacement in a direction going away from the rolling shaft section is possible when a pressing force is applied in that direction.

Construction is achieved that, together with preventing the occurrence of damage to a mandrel, is able to improve precision of the shape of a ring-shaped member after processing. A mandrel includes a pair of support shaft sections that are provided so as to be separated in the axial direction and so as to be concentric with each other, and a rolling shaft section that is concentrically provided in the axial direction between the pair of support shaft sections. One of the support shaft sections is provided in a state in which displacement in the axial direction with respect to the rolling shaft section is regulated. The other support shaft section is provided in a state in which displacement in a direction going away from the rolling shaft section is possible when a pressing force is applied in that direction.

A process of compressing a slug to have tapered ends, then reforming the slug to change the configuration to a shorter length with a larger diameter across the center of the slug. The slug is then reformed and a hole pressed there through, with the pressing of the partial hole reforming the configuration to have a near perfect radius with a hole through the slug, whereby a near prefect ball is made, and the ball has a hole there through.

A method for manufacturing an annular member includes: a cylindrical member forming step of forming a cylindrical member with an annular shape from a round bar material; and a cutting and separating step of cutting and separating the cylindrical member over an axial direction of the cylindrical member while rotating the cylindrical member, the cylindrical member being cut and separated by a shear force obtained by restraining molds, which apply an urging force to an outer circumferential surface of the cylindrical member, and by a restraining mold, which is provided with a gap on the outer circumferential surface of the cylindrical member, among a plurality of restraining molds provided on an inner circumferential surface side and an outer circumferential surface side of the cylindrical member along the axial direction, to obtain a plurality of annular members.

A method for manufacturing an annular member includes: a cylindrical member forming step of forming a cylindrical member with an annular shape from a round bar material; and a cutting and separating step of cutting and separating the cylindrical member over an axial direction of the cylindrical member while rotating the cylindrical member, the cylindrical member being cut and separated by a shear force obtained by restraining molds, which apply an urging force to an outer circumferential surface of the cylindrical member, and by a restraining mold, which is provided with a gap on the outer circumferential surface of the cylindrical member, among a plurality of restraining molds provided on an inner circumferential surface side and an outer circumferential surface side of the cylindrical member along the axial direction, to obtain a plurality of annular members.

A rotor bearing having a rolling bearing raceway in an unhardened core region of a rolling bearing ring element that further includes an outer layer hardened to a surface hardening depth wherein the rolling bearing raceway is formed by a roll, wherein a diameter of the roll is 8 to 25 times the surface hardening depth.

A rotor bearing having a rolling bearing raceway in an unhardened core region of a rolling bearing ring element that further includes an outer layer hardened to a surface hardening depth wherein the rolling bearing raceway is formed by a roll, wherein a diameter of the roll is 8 to 25 times the surface hardening depth.

A ring rolling device includes a drive roller and a rotatable revolving drum, in which five mandrels are rotatably mounted. Ring blanks can be mounted around the mandrels. By rotating the revolver drum, the mandrels move towards and away from the drive roller. The revolver drum is arranged in relation to the drive roller such that by rotating the revolver drum a decreasing roll gap is formed between a mandrel approaching the drive roller and the drive roller, in which roll gap a ring blank mounted around the mandrel is rolled during the rotating of the revolver drum. The revolver drum has four rotatably mounted support rollers, said support rollers supporting the mandrel in the direction of the rotational axis of the revolving drum, such that, during the rolling process, the mandrel is located between the support rollers and the press element.