Manufacturing method for bearing outer ring

摘要

When the column-shaped raw material 10 is subjected to an upsetting process, a simultaneous forward-backward extrusion process, a punching process, a rolling process and a finishing process in order, to obtain an outer ring 3 that constitutes a back-to back double-row angular ball bearing 3, in the simultaneous forward-backward extrusion process, using a floating die 31 having a bottom plate section 35 with a circular convex section 34 and a punch 33 having a punch side convex section 37 provided on an distal end thereof, the section closer to the center in the radial direction of the first intermediate material 11a is compressed in the axial direction, causing the metal material of the first intermediate material 11a to move outward in the radial direction and move approximately uniformly in both extrusion (forward and backward) direction of the punch 33, whereby the middle metal material 29 having a high degree of cleanliness of the column-shaped raw material 10 is exposed over the entire portion that will become the double-row outer-ring raceways 2.

主权项

1. A method for manufacturing a bearing outer ring having double-row back-to-back outer-ring raceways in two locations in an axial direction around an inner peripheral surface thereof, the method comprising steps of:
obtaining a first intermediate material by performing an upsetting process of compressing a metal circular column-shaped raw material in an axial direction thereof so that the first intermediate material has a middle section between end sections in an axial direction thereof and the middle section has an outer diameter that is greater than an outer diameter of each of the end sections; obtaining a second intermediate material by performing a simultaneous forward-backward extrusion process or a combination of a forward extrusion process and a backward extrusion process of compressing a center portion of the first intermediate material, such that the second intermediate material comprises a cylindrical section having a middle section in an axial direction thereof and a bulkhead portion that is provided on an inner-diameter side of the middle section of the cylindrical section; obtaining a third intermediate material by performing a punching process of punching out and removing the bulkhead portion of the second intermediate material such that the third intermediate material has a wholly cylindrical shape; obtaining a fourth intermediate material by performing a rolling process of plastically deforming an inner peripheral surface and an outer peripheral surface of the third intermediate material such that the fourth intermediate material has an outer peripheral surface that is a cylindrical surface with an outer diameter that substantially does not change in an axial direction of the fourth intermediate material, and has an inner peripheral surface that comprises a middle section between end sections in the axial direction of the fourth intermediate material where an inner diameter of the inner peripheral surface is smallest, and the middle section defines and separates inclined sections in the axial direction that incline so that an inner diameter of each of the inclined sections gradually increases toward an adjacent one of the end sections in the axial direction; and forming double-row outer-ring raceways around the inner peripheral surface of the fourth intermediate material by a finishing process of cutting away the inner peripheral surface of the fourth intermediate material; in the simultaneous forward-backward extrusion process or the forward extrusion process, a floating die, which comprises a peripheral wall section to which an elastic force in a backward direction is applied by an elastic member, and a bottom plate section that is located at a bottom portion of the peripheral wall section and that is provided in a center portion thereof with a circular convex section such that a first cylindrical formation space is formed between an outer peripheral surface of the circular convex section and an inner peripheral surface of the peripheral wall section, wherein the compressing of the center portion of the first intermediate material is between the floating die and an extrusion punch and causes the peripheral wall section of the floating die to lower against the elastic force of the elastic member due to friction that acts between the outer peripheral surface of the first intermediate material and the inner peripheral surface of the peripheral wall section when a metal material that is extruded outward in a radial direction of the first intermediate material due to the compressing of the center portion of the first intermediate material and a metal material that is located in a portion closer to an outside in the radial direction of the first intermediate material is caused to move into the first cylindrical formation space located in a forward extrusion direction of the extrusion punch.