Rolling/sliding member, toroidal continuously variable transmission using the same method of manufacturing rolling/sliding member

Abstract

A rolling/sliding member used for a toroidal continuously variable transmission according to the present invention is made of steel containing at least C: not less than 0.8 wt % and not more than 1.5 wt %, Si: not less than 0.9 wt % and not more than 2.1 wt % and Cr: not less than 2 wt % and not more than 5 wt %, and by applying surface hardening through machining to a surface whose surface hardness is set to not less than 60 HRC and not more than 64 HRC through quenching/tempering, surface compression residual stress thereof is set to not less than 700 MPa and not more than 1100 MPa. Furthermore, the amount of reduction of surface hardness when heated at 300° C. is set to not more than 1 HRC.

1 . A rolling/sliding member used for a toroidal continuously variable transmission, wherein the rolling/sliding member is made of steel containing at least: 
 C: not less than 0.8 wt % and not more than 1.5 wt %    Si: not less than 0.9 wt % and not more than 2.1 wt %    Cr: not less than 2 wt % and not more than 5 wt %    wherein by applying surface hardening through machining to a surface whose surface hardness is set to not less than 60 HRC and not more than 64 HRC through quenching/tempering, surface compression residual stress thereof is set to not less than 700 MPa and not more than 1100 MPa, and    the amount of reduction of surface hardness when heated at 300° C. is not more than 1 HRC.    
     
     
         2 . The rolling/sliding member according to  claim 1 , wherein the amount of retained austenite before the surface hardening is not less than 10 wt % and not more than 20 wt %.  
     
     
         3 . The rolling/sliding member according to  claim 1 , wherein an austenitizing temperature is not less than 870° C. and not more than 950° C. and an tempering temperature is not less than 200° C. and not more than 280° C.  
     
     
         4 . A method of manufacturing a rolling/sliding member used for a toroidal continuously variable transmission, comprising: 
 a quenching/tempering process of performing quenching/tempering on an intermediate material of the rolling/sliding member made of steel containing at least:    C: not less than 0.8 wt % and not more than 1.5 wt %    Si: not less than 0.9 wt % and not more than 2.1 wt %    Cr: not less than 2 wt % and not more than 5 wt %    at an austenitizing temperature of not less than 870° C. and not more than 950° C. and an tempering temperature of not less than 200° C. and not more than 280° C. to thereby set surface hardness of the intermediate material to not less than 60 HRC and not more than 64 HRC and the amount of retained austenite to not less than 10 wt % and not more than 20 wt %; and    a surface hardening process of applying surface hardening through machining to the intermediate material which has undergone the quenching/tempering process, thereby setting surface compression residual stress of the intermediate material to not less than 700 MPa and not more than 1100 MPa and setting the amount of reduction of surface hardness to not more than 1 HRC when heated at 300° C.    
     
     
         5 . A toroidal continuously variable transmission comprising: 
 an input disk having a concave curved raceway surface on a side;    an output disk having a concave curved raceway surface facing the raceway surface of the input disk on a side; and    rollers which are sandwiched between raceway surfaces of the respective disks in a rotatable manner and transmit torque between the respective disks through rolling and sliding between the respective disks,    wherein at least one of the input disk, output disk and rollers, which are rolling/sliding members, is the rolling/sliding member according to  claim 1 .    
     
     
         6 . The rolling/sliding member according to  claim 2 , wherein an austenitizing temperature is not less than 870° C. and not more than 950° C. and an tempering temperature is not less than 200° C. and not more than 280° C.