Hybrid Resistance/Ultrasonic Welding System and Method

Abstract

A hybrid resistance heating/ultrasonic welding method is used to join substrates. The resistance heating sufficiently softens or melts the substrates at an interface, and an ultrasonic wave is used solid state bond the substrates at the interface. The hybrid method can be used for both spot welding as well as continuous welding.

1 . A method comprising:
 providing a pair of substrates with a contact interface therebetween;   applying an electric current to said substrates to soften said substrates at the interface; and   applying an ultrasonic wave to said substrates to solid-state bond said substrates at the interface.   
     
     
         2 . The method of  claim 1 , wherein said ultrasonic wave is applied simultaneously with said electric current. 
     
     
         3 . The method of  claim 1 , wherein said ultrasonic wave is applied before said electric current. 
     
     
         4 . The method of  claim 1 , wherein each substrate of said pair of substrates is selected from the group consisting of steel, stainless steel, twinning induced plasticity steel, aluminum, magnesium, tungsten, titanium, cobalt, and nickel-based alloys. 
     
     
         5 . The method of  claim 1 , wherein a first substrate of said pair of substrates is formed of a first material and a second substrate of said pair of substrates is formed of a second different material. 
     
     
         6 . The method according to  claim 1 , wherein at least one substrate of said pair of substrates includes a coating. 
     
     
         7 . The method according to  claim 6 , wherein during application of said electric current, said coating is expelled from said interface between said substrates. 
     
     
         8 . The method according to  claim 1 , wherein application of said electric current melts said substrates at said interface to form a molten nugget. 
     
     
         9 . The method according to  claim 8 , wherein said ultrasonic wave is applied to said substrates to prevent formation of defects in said molten nugget as said molten nugget cools into a solidified nugget. 
     
     
         10 . The method according to  claim 1 , wherein said electric current is applied to said substrates by at least one electrode. 
     
     
         11 . The method according to  claim 10 , wherein said electrode is adapted to form a roller. 
     
     
         12 . The method according to  claim 1 , wherein said ultrasonic wave is applied by a sonotrode. 
     
     
         13 . The method according to  claim 12 , wherein said sonotrode is adapted to form a roller. 
     
     
         14 . The method according to  claim 1 , wherein said ultrasonic wave is applied to said substrates at a plurality of frequencies. 
     
     
         15 . The method according to  claim 1 , wherein said electric current is applied to said substrates by an electrode, said electrode including a plurality of teeth. 
     
     
         16 . A method comprising:
 feeding a pair of substrates through a first set of rollers, said first set of rollers adapted to apply an electric current through said substrates at an interface between said substrates;   feeding said pair of substrates through a second set of rollers, said second set of rollers adapted to apply an ultrasonic wave through said substrates at said interface; and   joining said pair of substrates at said interface by applying said electric current and said ultrasonic wave to said substrates.   
     
     
         17 . The method according to  claim 16 , wherein said second set of rollers is disposed downstream in a weld direction from said first set of rollers. 
     
     
         18 . The method according to  claim 16 , wherein said second set of rollers is disposed upstream in a weld direction from said first set of rollers. 
     
     
         19 . The method according to  claim 16 , wherein application of said electric current either softens or melts said substrates at said interface. 
     
     
         20 . The method according to  claim 16 , wherein said application of said ultrasonic wave solid state bonds said substrates at said interface.