Method for gun barrel manufacture using tailored autofrettage mandrels

Abstract

A method of manufacturing a monobloc gun barrel by calculating an optimal residual stress profile and then applying tailored autofrettage mandrels which are mechanically pressed down the bore of a large caliber barrel, the mandrel size optimized to create a residual stress distribution on the interior of the bore within the design constraints imposed by the worst-case heat flux scenario.

1 . A monobloc artillery barrel comprising an external surface subject to a constant liquid flow for cooling and a plastically deformed inner surface, said deformation created by mechanical autofrettage.  
   
   
       2 . The barrel of  claim 1  wherein favorable residual stresses are created as a result of said autofrettage.  
   
   
       3 . The barrel of  claim 2  wherein the favorable residual stresses are optimized to prevent barrel bore collapse and maximize fatigue life.  
   
   
       4 . The barrel of  claim 3  wherein the predicted fatigue life is 3070 cycles.  
   
   
       5 . The barrel of  claim 3  wherein the bore collapse margin is 1.04.  
   
   
       6 . The barrel of  claim 3  wherein an expected heat flux experienced by said barrel establishes a yield strength profile.  
   
   
       7 . The barrel of  claim 2  wherein autofrettage is achieved by pressing a tailored mandrel down said barrel.  
   
   
       8 . The barrel of  claim 3  wherein the geometry of the mandrel is tailored by adjusting a diameter, and a taper length.