Method of resistance spot welding aluminum alloy workpieces

Abstract

A method of resistance spot welding aluminum alloy workpieces together is disclosed that involves periodically texturing and dressing of at least one of the two electrode weld faces. The texturing and dressing steps help preserve the ability of the welding electrode to deliver electrical current through the overlapping aluminum alloy workpieces being welding despite the presence of one or more oxide layers on the surfaces of the workpieces and, as such, are effective in prolonging the useful life of the electrode(s).

1 . A method of maintaining a welding electrode during its use in resistance spot welding aluminum alloy workpieces together, the method comprising:
 texturing a weld face of the welding electrode to provide the weld face with a surface roughness;   performing resistance spot welding with the welding electrode to form a first number of resistance spot welds between overlapping aluminum alloy workpieces;   texturing the weld face again to provide the weld face with a surface roughness after the first number of individual resistance spot welds are performed;   performing resistance spot welding with the welding electrode to form a second number of resistance spot welds between overlapping aluminum alloy workpieces;   dressing the weld face to remove a depth of material of the welding electrode after the second number of individual resistance spot welds are performed; and   texturing the weld face to provide the weld face with a surface roughness after dressing of the weld face.   
     
     
         2 . The method as set forth in  claim 1 , further comprising initially shaping the weld face to have a radius of curvature ranging between 20 mm and 40 mm, inclusive. 
     
     
         3 . The method as set forth in  claim 1 , wherein the surface roughness achieved in each texturing step ranges between 2 μm and 50 μm, inclusive. 
     
     
         4 . The method as set forth in  claim 1 , wherein the first number of individual resistance spot welds is 10 to 20 individual resistance spot welds. 
     
     
         5 . The method as set forth in  claim 1 , wherein dressing the weld face is performed after 40 to 100 individual resistance spot welds are formed. 
     
     
         6 . The method as set forth in  claim 1 , wherein dressing the weld face removes a depth of material of the welding electrode ranging between 25 μm and 250 μm, inclusive. 
     
     
         7 . The method as set forth in  claim 1 , wherein dressing the weld face removes a depth of material of the welding electrode ranging between 50 μm and 150 μm, inclusive. 
     
     
         8 . A method of resistance spot welding aluminum alloy workpieces together, the method comprising:
 providing a first welding electrode and a second welding electrode, the first welding electrode having a first weld face and the second welding electrode having a second weld face, each of the first weld face of the first welding electrode and the second weld face of the second welding electrode being textured and having a peak-to-valley surface roughness;   forming a plurality of individual resistance spot welds between overlapping aluminum alloy workpieces, wherein forming each of the plurality of individual resistance spot welds comprises clamping the first weld face and the second weld face against opposed weld site surfaces of the overlapping of aluminum alloy workpieces and passing an electrical current between the weld faces;   texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time after forming the plurality of individual resistance spot welds to restore the peak-to-valley surface roughness to each of the first and second weld faces;   forming another plurality of individual resistance spot welds between overlapping aluminum alloy workpieces, wherein forming each of the another plurality of individual resistance spot welds comprises clamping the first weld face and the second weld face against opposed weld site surfaces of the overlapping of aluminum alloy workpieces and passing an electrical current between the weld faces;   dressing the first weld face and the second weld face to remove a depth of material from each of the first weld face and the second weld face that is the sufficient to remove contamination build-up derived from forming individual resistance spot welds between aluminum alloy workpieces.   
     
     
         9 . The method set forth in  claim 8 , wherein each of the first weld face and the second weld face is textured to have peak-to-valley surface roughness ranging from 2 μm and 50 μm, inclusive. 
     
     
         10 . The method set forth in  claim 8 , wherein each of the first weld face and the second weld face is spherically domed and has a radius of curvature ranging from 20 mm to 40 mm, inclusive. 
     
     
         11 . The method set forth in  claim 8 , wherein texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time comprises engaging each of the first and second weld faces with an abrasive media supported on a periphery of a texturing wheel and rotating the texturing wheel. 
     
     
         12 . The method set forth in  claim 8 , wherein texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time comprises grit blasting each of the first and second weld faces with abrasive particles. 
     
     
         13 . The method set forth in  claim 8 , further comprising:
 texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time after forming the another plurality of resistance spot welds, but before dressing, to restore the peak-to-valley surface roughness to each of the first and second weld faces.   
     
     
         14 . The method set forth in  claim 13 , wherein texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time comprises engaging each of the first and second weld faces with an abrasive media supported on a periphery of a texturing wheel and rotating the texturing wheel. 
     
     
         15 . The method set forth in  claim 13 , wherein texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode at the same time comprises grit blasting each of the first and second weld faces with abrasive particles. 
     
     
         16 . The method set forth in  claim 8 , further comprising:
 texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode after a depth of material has been removed from each of the weld faces during dressing.   
     
     
         17 . The method set forth in  claim 16 , wherein texturing the first weld face of the first welding electrode and the second weld face of the second welding electrode after a depth of material has been removed from each of the weld faces during dressing is performed at the same time. 
     
     
         18 . The method set forth in  claim 8 , wherein the depth of material removed from each of the first and second weld faces during dressing ranges from 25 μm and 250 μm, inclusive. 
     
     
         19 . The method set forth in  claim 8 , wherein each of the plurality of individual resistance spot welds and the another plurality of individual resistance spot welds includes between 10 and 20 individual resistance spot welds.