Research On OCT Based Laser Welding Quality On-line Inspection Technology

As an efficient and precise processing method,laser welding plays an important role in automobile manufacturing,electronic processing and other fields.The weld quality has an extremely important influence on the overall quality of the processed workpiece.Affected by factors such as the state of the workpiece,processing technology,environment,etc.,welding defects may occur during the forming process of the laser weld seam,and the size of the weld seam may be deviated.The weld forming size and welding defects are important factors that affect the reliability and stability of welding quality.Therefore,the precise detection of weld forming dimensions and welding defects is very important in the evaluation criteria of the overall quality of processed workpieces.The main research work of this paper is to propose an on-line detection method of weld size and welding defects,which can realize highprecision detection of weld size and welding defects.In this solution,the scanning device and the measuring device share a part of the optical components,which reduces the modification of the processing head.First of all,this paper has determined the on-line inspection system of weld quality by analyzing the principle of the spectral domain OCT system.A spectral domain OCT system with a central wavelength of 850 nm is designed and built.The influence of light source,optical fiber coupler,linear CCD and other components on the imaging quality of spectral domain OCT detection system is analyzed in detail,and the parameters and models of each component are determined according to the actual demand.Secondly,through the digital image processing algorithm,the scanned metal weld contour image is optimized to measure the weld size more accurately.The specific process is as follows: eliminating image noise,repairing weld contour fracture,extracting weld contour center line,extracting weld highest(low)point and weld boundary point,Then,the measurement of metal weld size and the detection of welding defects are completed by using the built spectral domain OCT system,and the detection results are compared with the manual detection results.This paper has completed the inspection of the quality of the plastic weld through the inspection of the size of the plastic weld,the gap between the two base metals and the bubble defect in the weld.The feasibility of on-line detection of weld quality by optical coherence tomography is verified,which provides a stable and reliable new method for weld quality detection.