Hydroformed vehicle frame assembly and method

Abstract

A method for forming a vehicle side rail structure includes forming a cylindrical tubular metal blank, forming a conical tubular metal blank, the conical tubular metal blank having a wider end portion and a narrower end portion, and joining the wider end portion of the conical tubular metal blank to one end portion of the cylindrical tubular metal blank by welding to form a welded tubular assembly. The method further includes bending the cylindrical tubular metal blank portion of the welded tubular assembly and hydroforming the welded tubular assembly by placing the welded tubular assembly into a hydroforming die cavity and pressuring an interior of the welded tubular assembly with hydroforming fluid so as to expand the welded tubular assembly into general conformity with surfaces defining the die cavity. The die cavity surfaces defines a generally octagonal shape along a portion thereof so as to conform the conical tubular metal blank portion of the welded tubular assembly therewith and thereby provide the conical tubular metal blank portion of the welded tubular assembly with a generally octagonal cross-sectional configuration.

In the claims:  
     
         1 . A method for forming a vehicle side rail structure, comprising: 
 forming a cylindrical tubular metal blank;    forming a conical tubular metal blank, said conical tubular metal blank having a wider end portion and a narrower end portion;    joining said wider end portion of said conical tubular metal blank to one end portion of said cylindrical tubular metal blank by welding to form a welded tubular assembly;    bending said cylindrical tubular metal blank portion of said welded tubular assembly;    hydroforming said welded tubular assembly by placing said welded tubular assembly into a hydroforming die cavity and pressuring an interior of said welded tubular assembly with hydroforming fluid so as to expand said welded tubular assembly into general conformity with surfaces defining said die cavity, said die cavity surfaces defining a generally octagonal shape along a portion thereof so as to conform said conical tubular metal blank portion of said welded tubular assembly therewith and thereby provide said conical tubular metal blank portion of said welded tubular assembly with a generally octagonal cross-sectional configuration.    
     
     
         2 . A method of forming a vehicle frame module including a pair of side rail structures interconnected by a cross structure, comprising: 
 (i) forming each of said pair of side-rail structures by: 
 forming a conical tubular metal blank, said conical tubular metal blank having a wider end portion an a narrower end portion;  
 joining said wider end portion of said conical tubular metal blank to one end portion of said cylindrical tubular metal blank by welding to form a welded tubular assembly;  
 hydroforming said welded tubular assembly by placing said welded tubular assembly into a hydroforming die cavity and pressuring an interior of said welded tubular assembly with hydroforming fluid so as to expand said welded tubular assembly into general conformity with surfaces defining said die cavity, said die cavity surfaces defining a generally octagonal shape along a portion thereof so as to conform said conical tubular metal blank portion of said welded tubular assembly therewith and thereby provide said conical tubular metal blank portion of said welded tubular assembly with a generally octagonal cross-sectional configuration;  
   (ii) forming a pair of connecting sleeves, each formed separately from said side rail structures, said connecting sleeves having a relatively narrowed end and a relatively wider end;    (iii) disposing said connecting sleeves in surrounding relation to respective ones of said side rail structures in the vicinity of said welded joints of said hydroformed welded tubular assemblies;    (iv) welding said relatively narrow ends of said connecting sleeves to said respective ones of said side rail structures;    (v) attaching opposite ends of a cross member to said connecting sleeves so that said cross member extends between said connecting sleeves.    
     
     
         3 . A method according to  claim 2 , further comprising bending said cylindrical tubular metal blank prior to said hydroforming.  
     
     
         4 . A method according to  claim 2 , wherein said connecting sleeves are each formed from a pair of sleeve members each constructed of a metal material and each sleeve member having two free end portions and wherein said disposing comprises placing each pair of members in surrounding relation with one of said side rail structures in the vicinity of the welded joint thereof and welding associated free end portions of each pair of sleeve members to one another.  
     
     
         5 . A method according to  claim 4 , wherein each sleeve member of each said pair has a C-shaped cross section.  
     
     
         6 . A method according to  claim 4 , wherein said relatively narrow ends of said connecting sleeves are each welded to a portion of an associated side rail structure that was formed from said cylindrical tubular metal blank portion.