Two piece axle shaft

Abstract

An axle shaft for a differential assembly. The axle shaft includes a shaft structure and a flange structure. The shaft structure has a coupling portion with an engagement surface. The flange structure is formed in a fine blanking operation and has a mounting aperture with a contact surface. The mounting aperture is sized to receive the coupling portion such that the engagement surface and the contact surface are engaged to one another so as to facilitate transmission of rotary power therebetween. The shaft structure and the flange structure are fixedly secured to one another to facilitate the transmission of rotary power therebetween.

What is claimed is:  
     
         1 . An axle shaft for a differential assembly, the axle shaft comprising: 
 a shaft structure having a coupling portion with an engagement surface;    a fine blanked flange structure having a mounting aperture with a contact surface, the mounting aperture being sized to receive the coupling portion such that the engagement surface and the contact surface are engaged to one another so as to facilitate transmission of rotary power therebetween; and    means for coupling the shaft structure and the flange structure.    
     
     
         2 . The axle shaft of  claim 1 , wherein the shaft structure is formed from a first material and the flange structure is formed from a second material that is different from the first material.  
     
     
         3 . The axle shaft of  claim 1 , wherein the shaft structure is formed from a generally tubular material.  
     
     
         4 . The axle shaft of  claim 3 , wherein the tubular material is welded tubing.  
     
     
         5 . The axle shaft of  claim 3 , wherein at least a portion of the shaft structure is formed in a rotary swaging operation.  
     
     
         6 . The axle shaft of  claim 1 , wherein the engagement surface has a non-circular shape that is configured to matingly engage the contact surface.  
     
     
         7 . The axle shaft of  claim 6 , wherein one of the engagement and contact surfaces includes a plurality of spline teeth for engaging a plurality of spline apertures formed in the other one of the engagement and contact surfaces.  
     
     
         8 . The axle shaft of  claim 7 , wherein the plurality of spline teeth are formed onto the shaft structure in a roll forming operation.  
     
     
         9 . The axle shaft of  claim 1 , wherein the coupling means includes at least one laser weld.  
     
     
         10 . The axle shaft of  claim 1 , wherein the coupling means includes at least one projection weld for fixedly coupling the shaft structure and the flange structure.  
     
     
         11 . The axle shaft of  claim 1 , wherein the coupling means includes an interference fit between the engagement surface and the contact surface.  
     
     
         12 . The axle shaft of  claim 1 , wherein the shaft structure includes an input spline that is adapted to matingly engage a spline aperture formed in a side gear of the differential assembly.  
     
     
         13 . The axle shaft of  claim 1 , wherein the coupling portion further includes a head portion that is at least partially disposed within a secondary mounting aperture formed into the flange structure.  
     
     
         14 . The axle shaft of  claim 13 , wherein the head portion has a diameter that is larger than a diameter of the mounting aperture.  
     
     
         15 . The axle shaft of  claim 13 , wherein the coupling means includes at least one laser weld for fixedly coupling the head portion to the flange structure.  
     
     
         16 . The axle shaft on  claim 13 , wherein the coupling means includes at least on projection weld for fixedly coupling the head portion and the flange structure.  
     
     
         17 . The axle shaft of  claim 13 , wherein the coupling means includes an interference fit between the head portion and the secondary mounting aperture.  
     
     
         18 . The axle shaft of  claim 13 , wherein the head portion includes a secondary engagement surface and the secondary mounting aperture has a secondary contact surface, the secondary engagement surface having a non-circular shape that is configured to matingly engage the secondary contact surface.  
     
     
         19 . The axle shaft of  claim 18 , wherein one of the secondary engagement and secondary contact surfaces includes a plurality of spline teeth for engaging a plurality of spline apertures formed in the other one of the secondary engagement and secondary contact surfaces.  
     
     
         20 . The axle shaft of  claim 19 , wherein the plurality of spline teeth are formed onto the head portion in a roll forming operation.  
     
     
         21 . The axle shaft of  claim 1 , wherein the flange structure is formed from a sheet material that has been processed in a rolling operation.  
     
     
         22 . The axle shaft of  claim 1 , wherein the shaft structure further comprises a bearing surface that is adapted to engage in a press-fit manner a race of a bearing.  
     
     
         23 . An axle assembly comprising: 
 an axle housing;    a differential assembly disposed within and rotatably supported by the axle housing, the differential assembly operatively receiving a drive torque input and distributing the drive torque input to a pair of output gears; and    a pair of axle shafts, each axle shaft including a shaft structure and a flange structure, the shaft structure having a coupling portion with an engagement surface, the flange structure being at least partially formed in a fine blanking operation and having a mounting aperture with a contact surface, the mounting aperture being sized to receive the coupling portion such that the engagement surface and the contact surface are engaged to one another so as to facilitate transmission of rotary power therebetween, wherein the shaft structure and the flange structure are fixedly secured to one another.    
     
     
         24 . The axle assembly of  claim 23 , wherein the shaft structure is formed from a first material and the flange structure is formed from a second material that is different from the first material.  
     
     
         25 . The axle assembly of  claim 23 , wherein the shaft structure is formed from a generally tubular material.  
     
     
         26 . The axle assembly of  claim 25 , wherein the tubular material is welded tubing.  
     
     
         27 . The axle assembly of  claim 25 , wherein at least a portion of the shaft structure is formed in a rotary swaging operation.  
     
     
         28 . The axle assembly of  claim 23 , wherein the engagement surface has a non-circular shape that is configured to matingly engage the contact surface.  
     
     
         29 . The axle assembly of  claim 28 , wherein one of the engagement and contact surfaces includes a plurality of spline teeth for engaging a plurality of spline apertures formed in the other one of the engagement and contact surfaces.  
     
     
         30 . The axle assembly of  claim 29 , wherein the plurality of spline teeth are formed onto the shaft structure in a roll forming operation.  
     
     
         31 . The axle assembly of  claim 29 , wherein at least one laser weld is employed to fixedly couple the flange structure and the shaft structure.  
     
     
         32 . The axle shaft of  claim 23 , wherein the coupling means includes at least one projection weld for fixedly coupling the shaft structure and the flange structure.  
     
     
         33 . The axle assembly of  claim 23 , wherein an interference fit between the engagement surface and the contact surface is employed to fixedly couple the flange structure and the shaft structure.  
     
     
         34 . The axle assembly of  claim 23 , wherein each of the shaft structures includes an input spline that is configured to matingly engage a spline aperture formed in one of the output gears of the differential assembly.  
     
     
         35 . The axle assembly of  claim 23 , wherein the coupling portion further includes a head portion that is at least partially disposed within a secondary mounting aperture formed into the flange structure.  
     
     
         36 . The axle assembly of  claim 35 , wherein the head portion has a diameter that is larger than a diameter of the mounting aperture.  
     
     
         37 . The axle assembly of  claim 35 , wherein at least one laser weld is employed to fixedly couple the head portion to the flange structure.  
     
     
         38 . The axle assembly of  claim 35 , wherein an interference fit between the head portion and the secondary mounting aperture is employed to fixedly couple the head portion to the flange structure.  
     
     
         39 . The axle assembly of  claim 35 , wherein the head portion includes a secondary engagement surface and the secondary mounting aperture has a secondary contact surface, the secondary engagement surface having a non-circular shape that is configured to matingly engage the secondary contact surface.  
     
     
         40 . The axle assembly of  claim 39 , wherein one of the secondary engagement and secondary contact surfaces includes a plurality of spline teeth for engaging a plurality of spline apertures formed in the other one of the secondary engagement and secondary contact surfaces.  
     
     
         41 . The axle assembly of claim  40 , wherein the plurality of spline teeth are formed onto the head portion in a roll forming operation.  
     
     
         42 . The axle assembly of  claim 23 , wherein the flange structure is formed from a sheet material that has been processed in a rolling operation.  
     
     
         43 . The axle assembly of  claim 23 , wherein the shaft structure further comprises a bearing surface that is adapted to engage in a press-fit manner a race of a bearing.