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介绍了一种大功率激光加工用新型宽带光斑成形抛物面镜的设计原理和实验结果。根据几何光学原理,采用光线追迹的方法对该抛物面镜的光斑进行分析,证明通过抛物面镜反射聚焦后,能够将原始圆形激光束整形为光强分布均匀的窄条形光斑。并利用该新型抛物面镜及横流CO2激光器,对45#钢进行了激光相变硬化研究,测量了淬火带尺寸和淬硬层深度,并对硬化层形貌及其金相组织进行了观察和分析。结果表明,当激光器输出功率为3 kW,窄条光斑长度12 mm,扫描速度15 mm/s时,该45#钢淬硬层硬度值可达540~580 HV0.3,是非淬硬层的3.5~4倍。淬硬层深度约为1 mm,单道淬火宽度10 mm以上,硬化层分布均匀。
The design principles and experimental results of a new type of wideband spot forming parabolic mirror for high power laser processing are introduced. According to the principle of geometrical optics, the light tracing method is used to analyze the light spot of the parabolic mirror. It is proved that the original circular laser beam can be shaped into a narrow strip light spot with uniform light intensity distribution after being reflected and focused by a parabolic mirror. The new type of parabolic mirror and cross-flow CO2 laser were used to study the phase transformation hardening of 45 # steel. The size of quenched zone and the depth of hardened layer were measured. The morphology and microstructure of hardened layer were observed and analyzed . The results show that the hardened layer hardness of 45 # steel reaches 540 ~ 580 HV0.3 when the output power of laser is 3 kW, the length of narrow spot is 12 mm and the scanning speed is 15 mm / s, which is 3.5 ~ 4 times. Hardened layer depth of about 1 mm, single channel quenching width of more than 10 mm, hardened layer evenly distributed.