Apparatus and Method for Tensioning a Gun Barrel Liner

Abstract

Tensioned gun barrel liners, and methods and apparatus for tensioning gun barrel liners are disclosed. Tensioned gun barrels have been shown to have superior performance. The apparatus allows for axial strain to be imparted into the gun barrel using mechanical means while other embodiments utilize thermal expansion of the material such as metal that is used for the gun barrel liner to introduce the strain and maintain it using other mechanical means or applied material such as composites.

What is claimed is: 
     
         1 . A method of tensioning a barrel liner, the method comprising:
 a) stretching the barrel liner along a longitudinal axial direction from at least one of a distal end and a proximal end of the barrel liner, to place the barrel liner under axial strain in a tensioned state; and   b) restraining the barrel liner in the tensioned state such that the barrel liner remains under said axial strain.   
     
     
         2 . The method of  claim 1 , wherein said restraining comprises one or more restraining elements. 
     
     
         3 . The method of  claim 1 , wherein said restraining comprises applying external material. 
     
     
         4 . The method of  claim 3 , wherein said external material comprises one or more of: composite material, advanced composite material and carbon composite material. 
     
     
         5 . The method of  claim 1 , wherein said stretching is achieved by thermal expansion. 
     
     
         6 . The method of  claim 5 , comprising:
 a) heating the barrel liner to cause said stretching;   b) applying a restraining element to the heated barrel liner in said tensioned state;   c) cooling the heated barrel liner;   wherein upon said cooling, the barrel liner remains in said tensioned state restrained by the restraining element from contracting, thereby resulting in said axial strain.   
     
     
         7 . The method of  claim 6 , wherein said cooling comprises applying external material to the heated barrel liner. 
     
     
         8 . The method of  claim 6 , wherein said restraining element comprises external material applied to the heated barrel liner and then subsequently cooled. 
     
     
         9 . An apparatus for tensioning a barrel liner, the apparatus comprising:
 an implement for engaging the barrel liner; and   securing elements for securing the implement to the barrel liner,   wherein the implement is operable to engage the barrel liner to cause axial strain in the barrel liner along a central axis of the barrel liner, the securing elements are operable to secure the barrel liner to the implement, to prevent displacement a portion of the implement relative to the barrel liner, such that movement of the said portion of the implement causes said axial strain.   
     
     
         10 . The apparatus of  claim 9 , wherein
 the implement is a rod; and   the securing elements comprise:
 a stop for placement at a proximal end of the barrel liner to stop the rod disposed within the barrel liner; and 
 a cap for capping a distal end of the barrel liner, the cap having an opening for allowing the rod therethrough, 
   wherein as the rod is introduced through the distal end of the barrel liner and progresses longitudinally along the central axis, the stop and the cap prevent further longitudinal displacement of the rod relative to the barrel liner, and instead causes said axial strain in the barrel liner.   
     
     
         11 . The apparatus of  claim 10 , wherein the rod is a threaded rod and the opening is threaded. 
     
     
         12 . A gun barrel produced by a process comprising:
 a) providing barrel liner and a structural external feature;   b) placing the barrel liner under axial strain; and   c) applying the external feature while the barrel liner is under said axial strain.   
     
     
         13 . The gun barrel of  claim 12 , wherein the barrel liner comprises one or more of steel, carbon steel, steel alloy, ceramic and composite material. 
     
     
         14 . The gun barrel of  claim 12 , wherein the barrel liner is steel or stainless steel. 
     
     
         15 . The gun barrel of  claim 12 , wherein the barrel liner is ceramic. 
     
     
         16 . The gun barrel of  claim 12 , wherein the external feature is a composite material. 
     
     
         17 . The gun barrel of  claim 16 , wherein the composite material comprises one or more of carbon, glass, Kevlar™ and fibrous reinforcing material. 
     
     
         18 . The gun barrel of  claim 16 , wherein the composite material comprises any one of epoxy, or any matrix polymer. 
     
     
         19 . The gun barrel of  claim 12 , wherein the external feature comprises a metal matrix. 
     
     
         20 . The gun barrel of  claim 12 , wherein the external feature comprises wire. 
     
     
         21 . The gun barrel of  claim 16 , wherein the composite is applied via filament winding. 
     
     
         22 . The gun barrel of  claim 16 , wherein the composite is applied through roll wrapping. 
     
     
         23 . The gun barrel of  claim 16 , wherein the composite is applied through braiding. 
     
     
         24 . The gun barrel of  claim 20 , wherein the wire is applied through a winding process. 
     
     
         25 . The gun barrel of  claim 12 , wherein the barrel liner is tensioned by a torqued threaded rod positioned in the center of the barrel. 
     
     
         26 . The gun barrel of  claim 12 , tensioned by thermal expansion. 
     
     
         27 . The gun barrel of  claim 12 , made from an existing barrel that is machined to a smaller diameter.