515 nm皮秒激光环切加工微孔实验研究

Experimental Study on 515 nm Picosecond LaserRing Cutting of Microholes

为解决毫/纳秒激光加工微孔质量差的问题,利用515nm皮秒激光对厚度为0.1mm的不锈钢进行环切法加工直径100μm的微孔实验。采用激光共聚焦显微镜对加工后形貌和质量进行观察与表征,研究激光能量密度、扫描速度和离焦量等因素对加工后微孔形貌与质量的影响规律。实验结果表明,能量密度对微孔内壁质量有直接的影响,在保证去除能力前提下,控制能量密度在6.45J/cm^2以下,可有效减小微孔内壁的热影响区。同时实验还发现,适当增加扫描速度能够改善环切加工微孔切口和内壁的质量。在激光能量密度6.45J/cm^2扫描速度200mm/s时,孔锥度为2.72°随着扫描速度的增大,锥度减小,最后稳定在2.29°左右,正离焦加工也能一定程度上减小孔的锥度。此研究结果表明,优化工艺参数能够加工出热影响区小、边缘质量好且锥度小的微孔。

In order to solve the problem of poor microhole quality in millisecond/nanosecond laser processing, the 515 nm picosecond laser was used to ring cutting stainless steel with a thickness of 0.1 mm to process microholes with a diameter of 100 μm. Laser confocal microscopy was used to observe and characterize the morphology and quality of the processed microstructure. The effects of laser energy density, scanning speed and defocusing amount on the morphology and quality of microholes after processing were studied. The experimental results show that the energy density has a direct influence on the inner wall quality of the microholes. Controlling the energy density below 6.45 J/cm^2 can effectively reduce the heat affected zone of the inner wall of the microholes under the premise of ensuring the removal ability. At the same time, it is found that appropriately increasing the seanning speed can improve the quality of the microhole incision and the inner wall of the ring cutting. When the laser energy density is 6.45 J/cm^2 and the scanning speed is 200 mm/s, the hole taper is 2.72 degrees. As the scanning speed increases,the taper decreases, and finally stabilizes at about 2.29 degrees. The taper of the hole can also be reduced to some extent by the positive defocusing process. The results of this study show that the optimized process parameters can process microholes with small heat affected zone, good edge quality and small taper.