电解液射流辅助激光微细加工技术研究

发布时间：2018-08-14 14:13

【摘要】：激光加工过程中,高功率、高能量的激光光束聚焦照射在材料表面,致使材料迅速熔化、汽化脱离材料表面,达到加工目的。激光加工具有加工效率高、无接触式加工、加工材料广泛等特点,但传统激光加工方式会不可避免地产生再铸层、微裂纹及热影响区高度集中等加工缺陷,降低了微结构的加工表面质量和使用寿命。本文提出电解液射流辅助激光微细加工技术,该技术将激光束与腐蚀性电解液射流束同轴作用于工件,在激光作用的同时腐蚀性电解液射流不断对加工区域进行冲刷、冷却和微腐蚀作用,可以降低再铸层厚度、减少微裂纹数量、消除热影响区高度集中现象。具体研究内容为:本文首先分析了激光加工中再铸层产生原因,研究了电解液射流辅助激光微细加工中涉及的材料去除机理和激光耦合电解液射流束机理;研究了电解液中激光的吸收理论、散射理论,并进行了两种波长激光(532nm、1064nm)在不同浓度、温度、流速的动态弱酸性电解液(NaHSO4、HF)中能量衰减性规律的试验研究,为复合加工中电解液工艺参数的选取提供了参考依据;建立了电解液射流辅助激光打孔加工中流场和温度场的数学模型,并利用有限元差分法在fluent 14.0、ANSYS软件上对数学模型进行迭代计算,得到了孔的演变过程及仿真加工工艺参数对孔形的影响规律,利用仿真加工参数进行实际复合加工打孔,对比孔的外观及尺寸,两者一致性好,验证了本文仿真的有效性;对比了不锈钢材(1Cr18Ni9Ti)和单晶硅材料(Si)在空气中激光加工、水射流辅助激光加工和电解液射流辅助激光加工孔的形貌及再铸层,验证电解液射流辅助激光加工可以减薄再铸层厚度、降低微裂纹数量及减少热影响区高度集中现象,最后在不锈钢材料(1Cr18Ni9Ti)上进行了打孔试验,研究了激光脉冲能量、激光重复频率、电解液浓度、电解液射流速度对材料去除量、再铸层厚度的影响规律,初步掌握了电解液射流辅助激光微细加工的基本加工工艺规律,为电解液射流辅助激光微细加工技术的进一步研究奠定基础。
[Abstract]:In the process of laser processing, high power and high energy laser beams focus on the surface of the material, which causes the material to melt rapidly and vaporize away from the surface of the material to achieve the purpose of processing. Laser machining is characterized by high processing efficiency, contactless machining, extensive processing materials, etc. However, the traditional laser machining method will inevitably produce defects such as recast layer, micro-cracks and high concentration of heat affected zone, etc. The machined surface quality and service life of microstructures are reduced. In this paper, the electrolytic jet assisted laser micro-machining technology is proposed. The technology coaxial the laser beam with the corrosive electrolyte jet beam on the workpiece, and the corrosive electrolyte jet continuously scour the processing area while the laser is acting on the workpiece. Cooling and micro-corrosion can reduce the thickness of the recast layer, reduce the number of microcracks and eliminate the phenomenon of high concentration of heat affected zone. The main contents of this paper are as follows: firstly, the causes of the recast layer in laser machining are analyzed, the material removal mechanism and the laser coupling electrolyte jet beam mechanism in the laser micro-machining assisted by electrolyte jet are studied. The absorption theory and scattering theory of laser in electrolyte have been studied, and the energy attenuation law of two kinds of wavelength laser (532nmNm ~ (1064nm) in dynamic weak acid electrolyte (NaHSO _ 4 / HF) with different concentration, temperature and flow rate has been studied. The mathematical model of flow field and temperature field in the process of electrolyte jet assisted laser drilling is established. The mathematical model is calculated iteratively by using finite element difference method in fluent 14.0ANSYS software. The evolution process of the hole and the influence of the simulation processing parameters on the hole shape are obtained. The simulation machining parameters are used to carry out the actual compound drilling. The appearance and size of the contrast hole are consistent, which verifies the validity of the simulation in this paper, and compares the laser processing of stainless steel (1Cr18Ni9Ti) and monocrystalline silicon material (Si) in air. Water jet assisted laser machining and electrolyte jet assisted laser machining can reduce the thickness of the recast layer, reduce the number of microcracks and reduce the high concentration of heat affected zone, and verify that the electrolyte jet assisted laser machining can reduce the thickness of the recast layer and the high concentration of the heat affected zone. Finally, the drilling experiments were carried out on stainless steel (1Cr18Ni9Ti), and the effects of laser pulse energy, laser repetition rate, electrolyte concentration and electrolyte jet velocity on the material removal and the thickness of the recast layer were studied. The basic processing rules of electrolyte jet assisted laser micromachining are preliminarily grasped, which lays a foundation for the further study of electrolyte jet assisted laser micro machining technology.
【学位授予单位】：沈阳理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG665

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