Method of manufacturing metal element for continuously variable transmission

Abstract

An inclined surface corresponding portion ( 30 ′) of a metal element raw material ( 23 ′) and inclined surface forming portions ( 47 b, 47 c ) of dies ( 47, 49 ) are parallel to each other and are in contact with each other without gap. Therefore, a press load required while forming a metal element ( 23 ) is suppressed to a minimum and durability of the dies ( 47, 49 ) is enhanced. In addition, recess portions ( 24 a, 26 a ) are formed on both rear surfaces of an ear portion ( 26 ) and a body portion ( 24 ) of the metal element ( 23 ) through pressing by using the dies ( 47, 49 ). Therefore, the sizes of both the recess portions ( 24 a, 26 a ) are adjusted to change radially inward/outward distributions of the press loads on the dies ( 47, 49 ), so that it is possible to prevent the dies from tilting and to reduce a difference in radially inward/outward plate thickness of the metal element ( 23 ).

What is claimed is: 
     
         1 . A method of manufacturing a metal element for a continuously variable transmission comprising:
 pressing and punching a belt plate-shaped metal element raw material ( 23 ′) having a constant cross section by using dies ( 47 ,  49 ) to manufacture a metal element ( 23 ), wherein the metal element ( 23 ) has a pair of ring slots ( 27 ) that allow a pair of metal rings ( 22 ) to be fitted, a neck portion ( 25 ) that is positioned between the pair of ring slots ( 27 ), an ear portion ( 26 ) that extends radially outward from the neck portion ( 25 ), and a body portion ( 24 ) that extends radially inward from the neck portion ( 25 ) and has saddle surfaces ( 28 ) being formed to respectively support inner circumferential surfaces of the metal rings ( 22 ); and wherein a locking edge ( 29 ) overlapping front edges of the saddle surfaces ( 28 ) and extending in a transverse direction, and an inclined surface ( 30 ) extending radially inward and rearward from the locking edge ( 29 ) are formed on a front surface of the body portion ( 24 ),   wherein an inclined surface corresponding portion ( 30 ′) of the metal element raw material ( 23 ′) and inclined surface forming portions ( 47   b ,  47   c ) of the dies ( 47 ,  49 ) are parallel to each other and are in contact with each other with no gap, and recess portions ( 24   a ,  24   b ,  26   a ) are formed on rear surfaces of both the ear portion ( 26 ) and the body portion ( 24 ) of the metal element ( 23 ) through the pressing by using the dies ( 47 ,  49 ).   
     
     
         2 . The method of manufacturing a metal element for a continuously variable transmission according to  claim 1 ,
 wherein a raw material recess portion ( 34 ) is formed in advance on a front surface or a rear surface of a neck portion corresponding portion ( 25 ′) of the metal element raw material ( 23 ′) to be subjected to the pressing by using the dies ( 47 ,  49 ).