Cold-forged hitch receiver and method of making the same

Abstract

A method for reinforcing an end of a metal tube, and a resultant receiver tube for a motor vehicle trailer hitch assembly, wherein the method and resultant tube does not require creating a fold in the metal tube to create a reinforcing lip. The integral lip is formed by the plastic deforming a length of the first end of the tube extending beyond the die wherein the deformable length is less than or equal to two times the wall thickness of the tube.

1 . A method for reinforcing an end of a metal tube, said method comprising the steps of: 
 a) providing an elongated tube having a substantially uniform wall thickness, said tube having inner and outer surfaces and first and second ends;    b) providing a die defining a cavity conforming to the outer surface of said tube;    c) placing said tube in said die cavity such that a length of said first end extends beyond said die cavity;    d) preventing movement of the tube longitudinally with respect to said die cavity;    e) providing a mandrel having a first portion adapted to fit within said tube through said first end and a second portion extending radially from said mandrel first portion having a tube deforming recess surface adapted to impinge upon said first end;    f) inserting said mandrel first portion into said first end until said tube deforming surface contacts said first end; and    g) advancing said mandrel under pressure thereby causing cold deformation of said first end, without creating a fold therein, and plastically deforming said first end within said mandrel recess thereby creating an integral, reinforced lip at said first end.    
   
   
       2 . The method of  claim 1 , wherein during step c, said length of said first end extending beyond said die cavity is less than or equal to two times the wall thickness of said tube.  
   
   
       3 . The method of  claim 2  wherein said mandrel first portion conforms to the inner surface of said tube.  
   
   
       4 . The method of  claim 2  wherein said tube has a circular cross section.  
   
   
       5 . The method of  claim 2  wherein said tube has a rectangular cross section.  
   
   
       6 . The method of  claim 2  wherein said tube comprises a hitch bar receiver tube.  
   
   
       7 . A method for forming an elongated receiver tube for a motor vehicle trailer hitch assembly of the type wherein said receiver tube has a hollow interior passage that receives a hitch bar, said method comprising the steps of: 
 a) providing an elongated tube having a substantially uniform wall thickness, said tube having inner and outer surfaces and first and second ends;    b) providing a die defining a cavity conforming to the outer surface of said tube;    c) placing said tube in said die cavity such that a length of said first end extends beyond said die cavity, said length being less than or equal to two times the wall thickness of said tube;    d) preventing movement of the tube longitudinally with respect to said die cavity;    e) providing a mandrel having a first portion adapted to fit within said tube through said first end and a second portion extending radially from said mandrel first portion having a tube deforming recess surface adapted to impinge upon said first end;    f) inserting said mandrel first portion into said first end until said tube deforming surface contacts said first end; and    g) advancing said mandrel under pressure thereby causing cold deformation of said first end, without creating a fold therein, and plastically deforming said first end within said mandrel recess thereby creating an integral, reinforced lip at said first end.    
   
   
       8 . The method of  claim 7  wherein said mandrel first portion conforms to the inner surface of said tube.  
   
   
       9 . The method of  claim 7  wherein said tube has a circular cross section.  
   
   
       10 . The method of  claim 7  wherein said tube has a rectangular cross section.  
   
   
       11 . An elongated receiver tube for a motor vehicle trailer hitch assembly, said receiver tube comprising: 
 a) an elongated hollow tube having first and second ends and a substantially uniform wall thickness; and    b) a lip extending radially-outwardly from said first end, said lip integrally formed with said hollow tube without folding said first end.    
   
   
       12 . The receiver tube of  claim 11 , wherein said lip is integrally formed with said tube through the plastic deformation of a length of said first end wherein said deformable length is less than or equal to two times the wall thickness of said tube.  
   
   
       13 . The receiver tube of  claim 11 , wherein said elongated hollow tube has a circular cross-section.  
   
   
       14 . The receiver tube of  claim 11 , wherein said elongated hollow tube has a rectangular cross-section.