Method for Producing Outer Ring Member of Constant Velocity Universal Joint

Abstract

A primary product is formed by performing forward extrusion of a work in the first step, and a secondary product is formed by performing swaging in the second step. In the third step, preliminary pushing of the upper surface of the secondary product is performed to obtain a tertiary product where a recess generally matching the longitudinal section in the axial direction of the bottom wall of a cup portion of the final product is formed in the upper surface. In the fourth step, a quaternary product having a cup portion provided with a ball rolling groove in the inner wall is formed by performing backward extrusion of the tertiary product by using a punch having a tip shape generally matching the longitudinal section of the recess. Finally, in the fifth step, an outer ring member is produced as a final product by performing ironing of the cup portion of the quaternary product.

1 . A method of manufacturing an outer race for use in a Barfield constant velocity universal joint having a shank and a cup member which are integrally formed with each other by forging, comprising:
 a first step of performing forward extrusion on a cylindrical workpiece which has been cut to a predetermined length to form a first form having a shank;   a second step of upsetting an upper portion of the first form exclusive of said shank to compress and diametrically enlarge the upper portion of the first form to form a second;   a third step of preliminarily pushing in an upper surface of said second form to form a third form having a recess formed in the upper surface which is essentially identical in axial vertical cross-sectional shape to a bottom wall of a cup member of a final product;   a fourth step of performing backward extrusion on said third form, using a punch whose distal end is shaped substantially identically to the vertical cross-sectional shape of said recess, to form a fourth form having a cup member with ball rolling grooves formed in an inner wall thereof; and   a fifth step of ironing the cup member of said fourth form.   
   
   
       2 . A method according to  claim 1 , wherein a round surface having a curved cross-sectional shape is circumferentially formed in a boundary between an upper surface of a head of said third form and an opening of said recess. 
   
   
       3 . A method according to  claim 1 , wherein said recess of said third form is defined by a circular flat surface having a diameter D 1  as viewed in plan and an annular slanted surface extending continuously from said circular flat surface to the opening and inclined at a tilt angle of θ1 to said circular flat surface. 
   
   
       4 . A method according to  claim 3 , wherein the vertical cross-sectional shape of a bottom wall formed deeply in the cup member of said fourth form includes a circular flat surface having a diameter D 2  as viewed in plan and an annular slanted surface extending continuously from said circular flat surface to the opening and inclined at a tilt angle of θ2 to said circular flat surface, and is essentially identical to the vertical cross-sectional shape of the recess of said third form (D 1 ≅D 2 , θ1=θ2). 
   
   
       5 . A method according to  claim 4 , wherein the vertical cross-sectional shape of the bottom wall formed deeply in the cup member of said outer race includes a circular flat surface having a diameter D 3  as viewed in plan and an annular slanted surface extending continuously from said circular flat surface to the opening and inclined at a tilt angle of θ3 to said circular flat surface, and is essentially identical to the vertical cross-sectional shapes of the recess of said third form and the bottom wall of said fourth form ( 70 ) (D 1 ≅D 2 ≅D 3 , θ1=θ2=θ3). 
   
   
       6 . A method according to  claim 1 , wherein the recess of said third form has an axial depth T 1  equal to or smaller than an axially spaced distance T 2  (T 1 ≦T 2 ) between a circular flat surface formed deeply in the cup member of said fourth form and inner terminal ends of said ball rolling grooves.