Over-molded net-shaped gear and manufact uring method

Abstract

A method of manufacturing a gear that employs an insert portion and a preform portion that is deformed about the insert portion to fixedly couple the insert portion and the preform portion while features, such as gear teeth, are formed on the preform portion. The insert portion can be formed to include a net-shaped hole that can be suited to slidingly but non-rotatably engage an axle shaft.

1 . A method of manufacturing a gear, the method comprising: 
 providing a die assembly having an upper die, a lower die and a mandrel, one of the upper die and the lower die defining a plurality of gear teeth, the upper and lower dies cooperating to form a die cavity, the mandrel being received into the die cavity;    providing an insert portion that is formed of a solid substantially void free metal, the insert portion having a hollow body and a flange, the hollow body having opposite axial end faces, the flange extending circumferentially about the hollow body between the opposite axial end faces of the hollow body;    positioning the insert portion onto the mandrel;    cutting a preform portion from a tubular billet, the tubular billet being formed of a metal;    positioning the preform portion within the die cavity such that the preform portion extends circumferentially about at least a portion of the insert portion; and    pressing the preform portion between the upper and lower dies to form a gear in a single stroke such that a plurality of gear teeth are formed on the preform portion, the preform portion deforming during the single stroke such that the flange is embedded into the preform portion to thereby fixedly couple the insert portion and the preform portion.    
   
   
       2 . The method of  claim 1 , wherein prior to pressing the preform portion the method comprises heating the preform portion.  
   
   
       3 . The method of  claim 2 , further comprising bonding the insert portion to the preform portion.  
   
   
       4 . The method of  claim 3 , wherein bonding the insert portion to the preform portion includes placing a material between the preform portion and the insert portion.  
   
   
       5 . The method of  claim 4 , wherein the material is a brazing material.  
   
   
       6 . The method of  claim 1  further comprising bonding the insert portion to the preform portion.  
   
   
       7 . The method of  claim 1 , wherein at least one rotational locking feature is formed on the insert portion, the rotational locking feature being formed such that the preform portion moves radially inward into the at least one rotational locking feature when the preform portion is pressed between the upper and lower dies to thereby inhibit relative rotation between the insert portion and the preform portion.  
   
   
       8 . The method of  claim 7 , wherein the at least one rotational locking feature includes a notch that is formed in the flange.  
   
   
       9 . The method of  claim 1 , wherein the flange includes a first axial side that is generally transverse to a longitudinal axis of the insert portion, and a second axial side that is opposite the first side, the second axial side tapering relative to the first axial side such that a radially outward side of the flange is thinner than a radially inward side of the flange.  
   
   
       10 . The method of  claim 1 , wherein the flange includes a first annular surface, a second annular surface and an outer surface that is coupled to the first and second annular surfaces, and wherein at least one of the first and second annular surfaces is tapered so that a thickness of the flange decreases with increasing distance from the hollow body.  
   
   
       11 . The method of  claim 1 , further comprising: 
 providing a tube; and    rolling or swaging the tube to at least partially form the insert portion.    
   
   
       12 . The method of  claim 11 , wherein the insert portion has a net shaped non-circular aperture formed therethrough that is adapted to slidingly but non-rotatably engage an axle shaft.  
   
   
       13 . A method for forming a side gear of a differential, the method comprising: 
 forming a metallic insert portion having a net shaped non-circular aperture formed therethrough that is adapted to slidingly but non-rotatably engage an axle shaft;    providing a die assembly having an upper die, a lower die and a mandrel, one of the upper die and the lower die defining a plurality of gear teeth, the upper and lower dies cooperating to form a die cavity, the mandrel being received into the die cavity;    positioning the insert portion onto the mandrel;    cutting a preform portion from a tubular billet, the tubular billet being formed of a metal;    positioning the preform portion within the die cavity such that the preform portion extends circumferentially about at least a portion of the insert portion; and    pressing the preform portion between the upper and lower dies to form a gear in a single stroke such that a plurality of gear teeth are formed on the preform portion, the preform portion deforming during the single stroke such that the flange is embedded into the preform portion to thereby fixedly couple the insert portion and the preform portion.    
   
   
       14 . The method of  claim 13 , wherein prior to pressing the preform portion the method comprises heating the preform portion.  
   
   
       15 . The method of  claim 14 , further comprising bonding the insert portion to the preform portion.  
   
   
       16 . The method of  claim 13 , further comprising bonding the insert portion to the preform portion.  
   
   
       17 . The method of  claim 13 , wherein at least one rotational locking feature is formed on the insert portion, the rotational locking feature being formed such that the preform portion moves radially inward into the at least one rotational locking feature when the preform portion is pressed between the upper and lower dies to thereby inhibit relative rotation between the insert portion and the preform portion.  
   
   
       18 . The method of  claim 17 , wherein the at least one rotational locking feature includes a notch that is formed in the flange.  
   
   
       19 . The method of  claim 13 , wherein the flange includes a first axial side that is generally transverse to a longitudinal axis of the insert portion, and a second axial side that is opposite the first side, the second axial side tapering relative to the first axial side such that a radially outward side of the flange is thinner than a radially inward side of the flange.  
   
   
       20 . The method of  claim 13 , wherein the flange includes a first annular surface, a second annular surface and an outer surface that is coupled to the first and second annular surfaces, and wherein at least one of the first and second annular surfaces is tapered so that a thickness of the flange decreases with increasing distance from the hollow body.