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热透镜效应是影响激光焊接质量的重要因素之一。本文描述了激光焊接的模式转变规律，实验测定了透镜焦距变化量与激光功率、激光作用时间的关系，研究了热透镜效应对焊接过程及焊缝成形的影响。结果发现，大功率激光焊接时，热透镜效应使聚焦透镜的焦距缩短并可能使焊接过程逐渐偏离预先设计的稳定焊接模式，从而导致焊接过程的不稳定和熔深的剧烈波动。并通过分析热透镜效应引起焊接模式转变的机理，提出了防止这种因热透镜效应引起的不稳定现象的措施。
Thermal lens effect is one of the important factors affecting the quality of laser welding. In this paper, the pattern transformation of laser welding is described. The relationship between the variation of lens focal length and the laser power and laser action time is experimentally determined. The effect of thermal lensing on the welding process and the weld formation is also studied. The results show that the thermal lens effect causes the focal length of the focusing lens to shorten during high-power laser welding, and may cause the welding process to deviate from the pre-designed stable welding mode, resulting in instability and sharp fluctuations of welding penetration. And by analyzing the mechanism of the thermal lens effect causing the welding mode transition, measures to prevent such instability caused by the thermal lens effect are proposed.