On-line monitoring and closed-loop control of power battery welding depth

Optical coherence tomography(OCT)was used to monitor the welding depth on line.The stability and focal length adaptability of OCT were studied.The results show that the depth results of OCT are in good agreement with the metallographic results,and the error is less than 3.65%.OCT technology is not sensitive to the change of welding conditions.With the change of welding power,welding speed and protection gas flow,the error of OCT depth results is stable between 0.24%and 3.65%.Within the fluctuation range of±2.5mm,the standard deviation of OCT depth results of different height welded parts is only 0.072mm,and the process capability index CMK is 3.51.The results show that OCT depth monitoring has excellent anti-interference ability and focal length adaptability,and can realize closed-loop control of welding depth.