Shaft assembly providing a surface for forming joints

Abstract

The present invention relates to an assembly that provides metallic ends to a composite shaft and a method of fabricating such an assembly. The composite shaft is preferably comprised of reinforced fibers. A metallic inner sleeve is positioned in the cavity of one end of the shaft. A metallic outer sleeve is positioned around the end of the shaft having the inner sleeve therein. The outer sleeve may include structural features, such as dimples, that ensure a stable connection between the sleeve and the shaft. The sleeves are compressibly forced onto the shaft, thereby forming the assembly. Both sleeves are metallic, and therefore provide a surface onto which weld joints can be formed. A preferred method of assembly includes the steps of expanding the inner sleeve and compressing the outer sleeve against the shaft.

We claim:  
     
         1 . A shaft assembly providing a surface for forming joints, said assembly comprising: 
 a composite shaft having an end portion and a body portion, said end portion having an inner and outer surface and defining an opening and a cavity;    a metallic inner sleeve having an exterior surface and being disposed within said cavity of said end portion of said shaft, said exterior surface adjacent said inner surface of said end portion of said shaft;    a metallic outer sleeve having an interior surface and being disposed around said end portion of said shaft, said interior surface adjacent said outer surface of said end portion of said shaft.    
     
     
         2 . A shaft assembly according to  claim 1 , wherein said shaft further comprises a taper portion between said end portion and said body portion, said inner sleeve extending from at least said opening to said taper portion.  
     
     
         3 . A shaft assembly according to  claim 1 , wherein said shaft includes fibers selected from the group consisting of boron, glass, carbon, graphite, Kevlar, spectra, and spectran.  
     
     
         4 . A shaft assembly according to  claim 1 , wherein said exterior surface of said inner sleeve is in continuous contact with said inner surface of said end portion of said shaft.  
     
     
         5 . A shaft assembly according to  claim 1 , wherein said interior surface of said outer sleeve is in continuous contact with said outer surface of said end portion of said shaft.  
     
     
         6 . A shaft assembly according to  claim 1 , wherein said interior surface of said outer sleeve further comprises at least one raised dimple, thereby forming an undulating pattern on said interior surface.  
     
     
         7 . A shaft assembly according to  claim 6 , wherein said end portion of said shaft is complimentary to said undulating pattern of said interior surface of said outer sleeve.  
     
     
         8 . A shaft assembly according to  claim 6 , wherein said dimple comprises a circular projection.  
     
     
         9 . A shaft assembly according to  claim 6 , wherein said dimple comprises an elongated projection.  
     
     
         10 . A shaft assembly according to  claim 1 , wherein said inner sleeve further comprises a first flange and said outer sleeve further comprises a second flange.  
     
     
         11 . A shaft assembly according to  claim 10 , further comprising a joint formed between said first and second flanges.  
     
     
         12 . A shaft assembly according to  claim 11  wherein said joint is a weld joint.  
     
     
         13 . A driveshaft assembly providing a surface for forming joints, said assembly, comprising: 
 a composite tubular driveshaft having an end portion and a body portion, said end portion having an inner and outer surface and defining a cavity;    a metallic inner sleeve having an exterior surface and being disposed around said cavity of said shaft, said exterior surface adjacent said inner surface of said end portion of said shaft;    a metallic outer sleeve having an interior surface and being disposed about said end portion of said shaft, said interior surface having dimples and being adjacent said outer surface of said end portion of said shaft.    
     
     
         14 . A driveshaft assembly according to  claim 13 , wherein said driveshaft includes fibers selected from the group consisting of boron, glass, carbon, graphite, Kevlar, spectra, and spectran.  
     
     
         15 . A driveshaft assembly according to  claim 13 , wherein said inner sleeve is partially disposed within said cavity.  
     
     
         16 . A driveshaft assembly according to  claim 5 , wherein said inner sleeve further comprises an angular portion and a flange.  
     
     
         17 . A driveshaft assembly according to  claim 13 , wherein said outer sleeve is partially disposed around said end portion of said shaft.  
     
     
         18 . A driveshaft assembly according to  claim 17 , wherein said outer sleeve further comprises a conical portion and a flange, said conical portion defining an angle adapted to prevent further sliding of said outer sleeve around said end portion of said shaft.  
     
     
         19 . A driveshaft assembly according to  claim 13 , wherein said inner sleeve further comprises a first flange and said outer sleeve further comprises a second flange.  
     
     
         20 . A driveshaft assembly according to  claim 19  wherein said inner sleeve further comprises a conical portion that defines an angle adapted to prevent further insertion of said inner sleeve into said cavity.  
     
     
         21 . A driveshaft assembly according to  claim 19 , wherein said outer sleeve further comprises a conical portion that defines an angle adapted to prevent further sliding of said outer sleeve around said end portion of said shaft.  
     
     
         22 . A driveshaft assembly according to  claim 19 , further comprising a joint formed between said first and second flanges.  
     
     
         23 . A driveshaft assembly according to  claim 22 , wherein said joint comprises a weld joint.  
     
     
         24 . A method of fabricating a shaft assembly providing a surface for forming joints, said method comprising: 
 selecting a composite shaft member having an end portion and a body portion, said end portion having an inner and outer surface and defining a cavity;    selecting a metallic inner sleeve having an exterior surface;    selecting a metallic outer sleeve having an interior surface;    disposing said inner sleeve within said cavity of said end portion of said shaft;    disposing said outer sleeve around said end portion of said shaft;    expanding said inner sleeve such that said exterior surface is adjacent said inner surface of said end portion of said shaft;    compressing said outer sleeve such that said interior surface of said outer sleeve is adjacent said outer surface of said end portion of said shaft.    
     
     
         25 . The method according to  claim 24 , wherein said inner sleeve further comprises a first flange and said outer sleeve further comprises a second flange.  
     
     
         26 . The method according to  claim 25 , further comprising forming a joint between said first and second flanges.  
     
     
         27 . The method according to  claim 26 , wherein said forming a joint includes forming a weld joint.  
     
     
         28 . The method according to  claim 24 , wherein said steps of expanding said inner sleeve and compressing said outer sleeve are performed simultaneously.  
     
     
         29 . The method according to  claim 24 , wherein said expanding said inner sleeve and compressing said outer sleeve are accomplished by hydraulics.  
     
     
         30 . The method according to  claim 24 , wherein said outer sleeve further comprises at least one dimple positioned on said interior surface of said outer sleeve.  
     
     
         31 . The method according to  claim 30 , wherein said compressing said outer sleeve continues until an undulating interface is formed between said interior surface of said outer sleeve and said outer surface of said shaft.  
     
     
         32 . The method according to  claim 24 , wherein said inner sleeve further comprises at least one dimple positioned on said exterior surface of said inner sleeve.  
     
     
         33 . The method according to  claim 32 , wherein said expanding said inner sleeve continues until an undulating interface is formed between said exterior surface of said inner sleeve and said inner surface of said shaft.