Plasma arc torch and method for improved life of plasma arc torch consumable parts

Abstract

A plasma arc torch and method for improving the life of the consumable parts of the plasma are torch, including the electrode, the tip and the shield cap. The method includes turbulating gas as it flows over the exposed surfaces of the electrode, tip and shield cap to increase turbulence in the hydrodynamic boundary layer of the gas flow, thereby enhancing convective heat transfer. The result of enhanced cooling is improved consumable parts life. For example, to increase the turbulence of the gas flow over the outer surface of the electrode, the plasma arc torch electrode has a roughened, or textured outer surface formed with dimples, axially extending grooves or spiraling grooves formed in the outer surface of the electrode. The inner and outer surfaces of the tip and the inner surface of the shield cap are similarly textured.

1 . An improvement to a textured electrode of a plasma arc torch, the improvement comprising a textured surface defining a smaller number of deeper grooves over a length of the textured electrode.  
     
     
         2 . The textured electrode according to  claim 1 , wherein the texturing is disposed along a lower end of the electrode.  
     
     
         3 . The textured electrode according to  claim 1 , wherein the texturing is disposed along a front face of the electrode.  
     
     
         4 . An electrode for use in a plasma arc torch of the type having a gas passage defined at least in part by an outer surface of the electrode and a tip surrounding the electrode in spaced relationship therewith and working gas flowing through the gas passage, the gas passage defining a flow having a laminar boundary layer attached to the outer surface of the electrode, wherein: 
 the outer surface of the electrode is textured to promote turbulence of the working gas flowing in the laminar boundary layer while not changing a flow pattern in a bulk region above the laminar boundary layer, wherein the working gas within the laminar boundary layer is turbulated.    
     
     
         5 . The textured electrode according to  claim 4 , wherein the textured outer surface is disposed along a front face of the electrode.  
     
     
         6 . In a textured electrode for use in a plasma arc torch, an improvement comprising modifying grooves of the textured electrode such that the textured electrode defines fewer grooves and deeper grooves.  
     
     
         7 . The improved textured electrode according to  claim 6 , wherein the grooves are disposed along a front face of the electrode.