Multiple beam laser welding apparatus

Abstract

A laser welding apparatus for use in industrial processing, which is operable to emit laser energy to weld blanks and the like together along a seamline. The emitted laser energy comprises a multiple beam of two or more coherent light sources. The apparatus is adapted to selectively reposition the orientation of the multiple beam relative to the seamline to compensate for gaps between the abutting portions of the workpieces to be joined.

We claim:  
     
         1 . An apparatus for welding together proximal edge portions of two workpiece blanks along a seamline comprising, 
 a laser for emitting a composite beam to weld said blanks together along said seamline,    said composite beam including a first laser beam and a second laser beam, each of said first and second laser beams being focused towards a portion of said blanks to be welded at respective focal areas having an optic centre, wherein the optic centres of said first and second laser beams are spaced from each other and each define one end of a focal line of said composite beam,    a positioning mechanism for-selectively altering the orientation of said composite beam to move said focal line relative to said seamline between a first oriented position relative to said portion of said seamline, and a second oriented position relative to said portion of said seamline, said second oriented position being moved from said first position,    a device for sensing spacing between the abutting edge portions of the blanks at said portion of said blanks, and    wherein the positioning mechanism is operable to change the orientation of said composite beam and move said focal line to either said first oriented position or said second oriented position depending on said sensed spacing.    
     
     
         2 . An apparatus as claimed in    claim 1   , wherein said optic centres are offset from each other by a distance between about 0.1 mm to 3 mm.  
     
     
         3 . An apparatus as claimed in    claim 2   , wherein the focal area of each of said first and second laser beams at said seamline has a divergence radius selected at between about 0.2 mm and 1 mm.  
     
     
         4 . An apparatus as claimed in    claim 1   , wherein the device for sensing spacing between the abutting edge portions comprises a coherent light source, and 
 a sensor for sensing light from said coherent light source.    
     
     
         5 . An apparatus as claimed in    claim 1   , wherein said laser includes a laser head which is movable along a path substantially aligned with said seamline, and 
 said apparatus further includes a drive activatable to move said laser head along said path, and wherein the speed of movement of said laser head along said path is related to operating factors selected from the group consisting of the sensed spacing and the position of said focal line relative to said portion of said blanks to be welded.    
     
     
         6 . A laser apparatus for welding together substantially abutting edge portions of two sheet blanks along a seamline, the apparatus comprising: 
 a laser head operable to emit-laser energy to weld said blanks together along the seamline,    a positioning mechanism operable to change the orientation of said laser energy relative said seamline,    a sensing device for sensing spacing between the abutting edge portions of the blanks, and    a controller for controlling the positioning mechanism in response to the sensed spacing,    wherein said laser energy includes a multiple beam of two laser beams, each of said laser beams having an optic center spaced from the other and defining one end of a focal line.    
     
     
         7 . An apparatus as claimed in    claim 6    wherein the focal area of each of said laser beams has a divergence radius selected at between about 0.2 and 1.0 mm at said seamline.  
     
     
         8 . An apparatus as claimed in    claim 1   , wherein said composite beam further includes a third laser beam, 
 said third laser beam being focused towards said blanks at a focal area having an optic centre, wherein the optic centre of the third laser beam is intersected by the focal line.    
     
     
         9 . An apparatus as claimed in    claim 1   , wherein said composite beam further includes a third laser beam, 
 said third laser beam being focused towards said blanks at a focal area having an optic centre, wherein the optic centre of the third laser beam is spaced from the focal line.    
     
     
         10 . An apparatus as claimed in    claim 6   , wherein said optic centers are spaced a distance between about 0.1 mm to 3 mm.  
     
     
         11 . An apparatus as claimed in    claim 5   , wherein the focal area of each of said first and second laser beams has a divergence radius selected at between about 0.2 mm and 1 mm at said seamline.  
     
     
         12 . An apparatus as claimed in    claim 6   , wherein said sensing device comprises a coherent light source, and 
 a sensor for sensing light from said coherent light source.    
     
     
         13 . A method of using an apparatus to weld together abutting portions of two workpiece blanks along a seamline, the apparatus including, 
 a laser device for emitting a composite beam to weld said blanks together along said seamline,    said composite beam including a first laser beam and a second laser beam, each of said first and second laser beams being focused towards a portion of said blanks to be welded at respective focal areas having an optic center, wherein the optic centres of said first and second laser beams are spaced from each other and each define one end of a focal line of said composite beam,    a positioning mechanism for selectively varying the orientation of said output composite beam to move said focal line relative to said seamline between a first oriented position wherein said focal line is moved to a first orientation relative to said seamline, and a second oriented position wherein said focal line is moved to a second orientation relative to said seamline, the second oriented position being moved from said first oriented position,    wherein said abutting portions of said workpiece blanks are welded by the steps of: 
 activating said laser device to direct said composite beam towards said seamline portions,  
 moving said composite laser beam and said sheet blanks relative to each other to move said focal line substantially along said portion of said blanks to be welded,  
 substantially simultaneously with said step of moving, activating said positioning mechanism to move said focal line relative to said portion of said seamline to one of said first oriented position and said second oriented position determined by the spacing between the workpiece blanks at said portion.  
   
     
     
         14 . A method as claimed in    claim 13   , wherein during said step of moving said laser beam, 
 said laser beam and said sheet blanks are moved relative to each other at a speed determined by at least one of the position of the focal line relative to the portion of the blanks to be welded and the spacing between the workpiece blanks at said portion.    
     
     
         15 . A method as claimed in    claim 13   , wherein said apparatus further includes a device for determining spacing between the abutting portions of the blanks, and 
 wherein said method includes the further step of determining the spacing between the adjacent portions of the blanks at said portion of said blanks to be welded prior to moving said focal line therealong.    
     
     
         16 . The method as claimed in    claim 13   , wherein said laser device comprises a yttrium aluminum garnet laser.  
     
     
         17 . A method as claimed in    claim 16   , wherein said apparatus further includes a sensor for sensing spacing between the abutting portions of the blanks, and 
 wherein said method includes the further step of sensing the spacing between the adjacent portions of the blanks at said portion of said blanks to be welded.    
     
     
         18 . The apparatus of    claim 6   , further comprising 
 a drive for moving said laser head and said energy beam along said seamline, said drive activatable to vary the speed of movement of said laser head depending on the spacing between the edge portions of the blanks.    
     
     
         19 . The apparatus of    claim 18   , further comprising a power regulator to vary the energy beam energy output depending on the spacing between the edge portions of the blanks.