Battery Laser Welder

A major EV manufacturing company developed a novel clamping device to hold EV battery cells in position for welding the current collector in place. An OEM had built a machine with a 3 axis linear motor gantry, multiple confocal displacement sensors, and a laser welder. However, they had not been able to get the system to work consistently or come close to the required cycle time. The system needed to be entirely rewritten to take advantage of the high-end hardware to accurately scan and weld the battery packs. In addition, this Beckhoff system needed to be integrated into the Allen-Bradley line controller PLC.
Maskine worked with the mechanical engineer to develop an algorithm which would calibrate the confocal laser sensors to the frame of reference of the fixture. This involved both simple Linear X, Y, Z offset calibrations, but also developing a rotation offset which would calibrate X, Y, Z encoder position to the appropriate rotation angle.
Once a calibrated frame of reference had been established, Maskine programmed the system to scan the Z positions of the pack and determine the actual positions in relation to the fixture frame of reference at the lowest cycle time possible. In order to achieve this, the distance sensors were used to develop a plane compensation calibration which is communicated to the laser to weld the cells. To minimize cycle time, a high end Beckhoff CX6030 was used which allowed the motion calculation to take place every 250us allowing a high resolution even at high speed.
After the pack calibration has finished, the plane compensation offset data is communicated to the laser to fine tune the original welding patterns. Finally, the current collector is welding to cells through coordinated motion of the gantry and the laser welder.
The combination of the novel clamping fixture, high-accuracy calibration and welding procedure resulted in a reduction in cycle time from 8 minutes to 1.5 minutes at a critical bottleneck in the vehicle manufacturing line.