Laser welding method

Abstract

A laser welding method and apparatus includes a laser manipulator that directs a laser beam emitted from a laser generator at various predetermined angles toward predetermined positions within a laser work zone. A transport device passes workpieces through the laser work zone where the laser beam manipulator can direct a laser beam at desired interfacing portions of each workpiece to weld those interfacing portions together. The controller is programmed to cause the manipulator to weld the workpieces without halting their motion through the laser work zone.

What is claimed is:  
     
         1 . A laser welding apparatus for welding workpieces transported by a conveyor system, the apparatus comprising: 
 a laser generator;    a laser manipulator configured and positioned to direct a laser beam emitted from the laser generator;    a controller connected to the laser manipulator and configured to cause the laser manipulator to direct a laser beam from the laser generator at various predetermined angles toward predetermined positions within a laser work zone;    a transport device disposed adjacent the laser work zone and configured to pass workpieces through the laser work zone where the laser beam manipulator can direct a laser beam at desired interfacing portions of each workpiece to weld those interfacing portions together; and    the manipulator being configured to weld the workpieces without halting workpiece motion through the laser work zone.    
     
     
         2 . A laser welding apparatus as defined in  claim 1  in which the controller is configured to cause the laser manipulator to maintain a fixed focus length from a workpiece as the workpiece moves through the laser work zone.  
     
     
         3 . A laser welding apparatus as defined in  claim 1  in which the laser manipulator is a laser beam manipulator configured to direct a laser beam from the laser generator without moving the laser generator.  
     
     
         4 . A laser welding apparatus as defined in  claim 3  in which the laser beam manipulator includes a movable laser beam directing mirror configured to direct a laser beam from the laser generator in desired directions in response to signals received from the controller  
     
     
         5 . A laser welding apparatus as defined in  claim 3  in which the laser beam manipulator includes a flexible fiber optic cable that directs the beam in whatever direction a distal end of the cable is aimed.  
     
     
         6 . A laser welding apparatus as defined in  claim 4  in which the laser beam manipulator includes beam-focusing optics disposed between the laser generator and the mirror and configured and positioned to focus a laser beam from the generator onto the mirror.  
     
     
         7 . A laser welding apparatus as defined in  claim 3  in which the laser generator is disposed remote from the laser work zone.  
     
     
         8 . A laser welding apparatus as defined in  claim 1  in which: 
 the apparatus includes a pallet orientation sensor connected to the controller and configured to detect pallet orientation on the transport device; and  
 the controller is configured to compensate for pallet orientation variations when commanding laser beam manipulator movement.  
 
     
     
         9 . A laser welding apparatus as defined in  claim 1  in which: 
 the apparatus includes a motion sensor connected to the controller and configured to sense workpiece speed through the laser work zone and to send a signal to the controller corresponding to that speed, and  
 the controller is configured to respond to such a signal by modifying commands to the laser beam manipulator so that the laser beam manipulator continuously re-directs and focuses the laser beam in such a way as to compensate for workpiece speed while welding each workpiece.  
 
     
     
         10 . A laser welding apparatus as defined in  claim 1  in which: 
 the apparatus includes a position sensor connected to the controller and configured to sense workpiece position as each workpiece moves through the laser work zone; and  
 the controller is configured to track workpiece position in response to signals received from the position sensor.  
 
     
     
         11 . A laser welding apparatus as defined in  claim 10  in which the position sensor includes an optical sensor configured to optically determine the position of a workpiece passing through the laser work zone.  
     
     
         12 . A laser welding apparatus as defined in  claim 10  in which the position sensor includes a laser range finder configured to detect the position of a workpiece passing through the laser work zone.  
     
     
         13 . A laser welding apparatus as defined in  claim 1  in which the transport device includes a variable-speed conveyor configured to change speed in accordance with the number of workpieces passing through the laser work zone at a given time.  
     
     
         14 . A laser welding apparatus as defined in  claim 13  in which the variable-speed conveyor is configured to change speed in accordance with the amount of welding required by a workpiece passing through the laser work zone.  
     
     
         15 . A laser welding apparatus as defined in  claim 1  in which the controller is configured to direct the laser manipulator to weld pluralities of workpieces supported on single pallets moving through the laser work zone.  
     
     
         16 . A laser welding apparatus for welding workpieces supported on a pallet transported by a conveyor system, the apparatus comprising: 
 a laser generator;    a laser manipulator configured and positioned to direct a laser beam emitted from the laser generator;    a controller connected to the laser manipulator and configured to cause the laser manipulator to direct a laser beam from the laser generator at various predetermined angles toward predetermined positions within a laser work zone;    a transport device disposed adjacent the laser work zone and configured to pass workpieces supported on pallets through the laser work zone where the laser beam manipulator can direct a laser beam at desired interfacing portions of each workpiece to weld those interfacing portions together;    a pallet orientation sensor connected to the controller and configured to detect pallet orientation on the transport device; and    the controller is configured to compensate for pallet orientation variations when commanding laser beam manipulator movement.    
     
     
         17 . A laser welding apparatus for welding workpieces supported on a pallet transported by a conveyor system, the apparatus comprising: 
 a laser generator;    a laser manipulator configured and positioned to direct a laser beam emitted from the laser generator;    a controller connected to the laser manipulator and configured to cause the laser manipulator to direct a laser beam from the laser generator at various predetermined angles toward predetermined positions within a laser work zone;    a transport device disposed adjacent the laser work zone and configured to pass workpieces through the laser work zone where the laser beam manipulator can direct a laser beam at desired interfacing portions of each workpiece to weld those interfacing portions together; and    the controller is configured to direct the laser manipulator to weld pluralities of workpieces supported on single pallets disposed in the laser work zone.    
     
     
         18 . A laser welding apparatus as defined in  claim 17  in which the controller is configured to direct the laser manipulator to weld pluralities of different workpieces supported on single pallets in the laser work zone.  
     
     
         19 . A laser welding apparatus as defined in  claim 17  in which the apparatus includes a pallet reader connected to the controller and configured and positioned to send signals to the controller corresponding to information read from passing pallets.  
     
     
         20 . A laser welding apparatus as defined in  claim 19  in which the pallet reader is configured to optically read information affixed in a visual format to respective passing pallets.  
     
     
         21 . A laser welding apparatus as defined in  claim 19  in which the pallet reader is configured to electronically read memory devices affixed to respective passing pallets.  
     
     
         22 . A laser welding apparatus as defined in  claim 17  in which the apparatus includes a pallet programmer connected to the controller and configured and positioned to upload information to memory devices supported on the pallets.  
     
     
         23 . A laser welding apparatus as defined in  claim 17  in which the transport device includes: 
 a main conveyor configured to transport pallets to the laser welding cell;  
 a return conveyor configured to transport pallets of welded workpieces to the respective loading stations; and  
 a recycle conveyor positioned to return pallets carrying welded workpieces back to the laser welding cell.  
 
     
     
         24 . A laser welding apparatus as defined in  claim 17  further including: 
 a pallet reader connected to the controller and configured and positioned to send signals to the controller corresponding to information read from passing pallets; and  
 a pallet programmer connected to the controller and configured and positioned to upload information to memory devices supported on the pallets.  
 
     
     
         25 . A method of welding workpieces supported on a pallet transported by a conveyor system; the method including the steps of: 
 providing a laser generator and a laser manipulator configured and positioned to receive a laser beam emitted from the laser generator and to direct that beam at various points within a laser work zone;    providing a transport device adjacent the laser work zone and configuring the transport device to pass workpieces through the laser work zone;    providing a workpiece on the transport device;    causing the transport device to transport the workpiece through the laser work zone; and    welding interfacing portions of the workpiece together by causing the laser beam manipulator to direct a laser beam at the interfacing portions as the workpiece is moving through the laser work zone    
     
     
         26 . The method of  claim 25  including the additional steps of: 
 providing a controller connected to the laser manipulator; and  
 programming the controller to cause the laser manipulator to direct a laser beam from the laser generator at various predetermined angles toward predetermined positions within the laser work zone.  
 
     
     
         27 . The method of  claim 26  including the additional steps of: 
 providing a pallet reader connected to the controller; and  
 configuring and positioning the reader to read information from passing pallets; and  
 the step of programming the controller includes: 
 causing the reader to send signals to the controller that correspond to information read from passing pallets; and  
 commanding laser manipulator movement based on the signals received from the reader.  
 
 
     
     
         28 . The method of  claim 25  in which: 
 the step of providing a workpiece on the transport device includes supporting the workpiece on a pallet and providing the pallet on the transport device; and  
 the step of transporting the workpiece includes causing the transport device to transport the pallet through the laser work zone.  
 
     
     
         29 . The method of  claim 28  in which: 
 the step of providing a workpiece on the transport device includes the additional step of supporting at least one additional workpiece on the pallet; and  
 the welding step includes causing the laser beam manipulator to direct the laser beam at interfacing portions of each workpiece as they move together through the laser work zone.  
 
     
     
         30 . The method of  claim 28  including the additional steps of: 
 providing a plurality of pallets;  
 supporting different numbers of workpieces on certain of the pallets,  
 providing the pallets on the transport device;  
 causing the transport device to serially transport the pallets through the laser work zone; and  
 adjusting the speed of the transport device to correspond to the number of workpieces supported on each pallet as it passes through the laser work zone.  
 
     
     
         31 . The method of  claim 25  in which the step of welding interfacing portions of the workpiece together includes configuring the manipulator to automatically weld the workpieces without halting workpiece motion through the laser work zone.  
     
     
         32 . The method of  claim 25  including the additional steps of: 
 providing a pallet programmer adjacent the transport device;  
 connecting the programmer to the controller;  
 configuring and positioning the programmer to upload information to a memory device supported on the pallet as the pallet passes by the programmer;  
 transmitting information to the memory device by causing the controller to transmit information to the programmer; and  
 causing the programmer to upload corresponding information to the memory device.