【作者】 张华；

【导师】 徐家文；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 随着现代制造业的发展,集成创新成为制造业技术创新的重点。喷射液束电解—激光复合加工正是基于制造技术集成创新理念而提出的一项将电解加工与激光加工进行复合的新型加工方法。该方法通过施加与聚焦激光束同轴的带负电喷射电解液束形成工具阴极,并和激光束共同作用于工件,其加工原理是以激光加工为主快速去除材料,同时被阴极化的喷射电解液束对加工区的冲刷、冷却和电解作用在线去除激光加工所产生的再铸层。该方法涉及激光在电解液中的衰减特性、激光在电解液中作用于金属靶材的力学效应以及激光作用材料的热物理过程和喷射电解液束作用材料的电解过程之间的交互作用等有待研究的学科交叉知识点。本文以实现喷射液束电解—激光复合加工技术为主要目的,进行了以下研究工作:1.根据水溶液对激光的吸收、散射的理论分析,采用自行设计制造的装置实验研究了激光在电解液中的衰减特性及电解液浓度和温度的影响,为设计喷射液束电解—激光复合加工试验系统提供了重要的理论与试验依据。2.根据激光在液体中作用于金属靶材产生的力学效应的理论分析,基于压电加速度传感器测振原理,通过对电解液中悬臂梁不锈钢靶材在激光作用后的振动测试,研究了电解液中激光作用于金属靶材的力学效应,分析了喷射液束电解—激光复合加工中激光热—力效应去除材料的作用机理,揭示了激光在电解液中作用于金属靶材的力学效应有利于排除金属熔化物而减薄再铸层。3.基于喷射液束电解—激光复合加工特点的分析,总结出了该加工方法对试验系统的总体技术要求。根据这些技术要求以及激光在电解液中的衰减特性和力学效应的研究结果,研制了符合喷射液束电解—激光复合加工条件的试验系统,并对关键部件——喷射装置进行了分析和优化设计。4.根据对激光加工热—力作用机理和电解加工电化学作用机理的分析,基于温度场和电场理论,建立了喷射液束电解—激光复合加工二维数学模型,利用时域上独立计算,空域上边界迭加变换的方法,采用有限元分析软件进行了数值模拟并进行了试验验证,揭示了喷射液束电解—激光复合加工的作用机理,为后续试验研究奠定了基础。5.采用自行研制的试验系统,利用纳秒红外激光、毫秒绿光激光对不锈钢材料、镍基高温合金材料进行了喷射液束电解—激光复合加工的试验研究,证实了喷射液束电解—激光复合加工的可行性,复合加工在保持激光加工相对高的加工效率的前提下,使再铸层厚度减薄至5μm以下,而且加工表面无热影响区,加工精度更好。在此基础上,根据不同工艺参数的对比试验结果,总结出了该复合加工的基本工艺规律。通过上述理论分析和试验研究,表明了喷射液束电解—激光复合加工可以实现激光加工与电解加工的复合,能够获得优质高效的加工效果,该加工方法为航空发动机热端部件气膜冷却孔的加工提供了新的技术途径。更多还原

【Abstract】 With the development of modern manufacturing technology, integrated innovation has become the focus of innovation in manufacturing technology. The hybrid processing of jet electrochemical machining and laser beam machining (JECM-LBM) is a new processing method which is combined with laser processing and electrochemical machining based on the idea of manufacturing innovation. The method bases on the application of a jet electrolyte, being aligned coaxially with the focused laser beam, on the workpiece surface. The processing principle is that material is removed mainly by laser processing and the recast layer is removed by the effect of jet electrolyte which consists of cooling to workpiece, transporting debris and electrochemical reaction with materials. The research of the new processing method involves some interdisciplinary knowledge points to be studied such as the laser attenuation in the electrolyte, the mechanical effect of the metal target by the laser in the electrolyte, and the interaction between the thermal physical process of laser and electrolytic process of jet electrolyte.The achievement of the new technology of JECM-LBM was the main goal in this research subject and the main research contents were included:1. According to the theoretical analysis of laser absorption and scattering of solution, the properties of laser attenuation in the electrolyte and the influence coefficient with concentration & temperature were researched with self-designed and manufactured set up. The results of the laser attenuation in the electrolyte provided the theoretical and experimental basis for the design of the JECM-LBM experimental system.2. According to the theoretical analysis of laser-induced mechanical effect of metal target in liquid, the vibration of stainless cantilever target by laser in the electrolyte were tested based on the test mechanism of piezoelectric accelerometer. The processing mechanism with the thermal- mechanical effects of laser in JECM-LBM was analyzed by the test. It was revealed that laser-induce mechanical effect of metal target has the benefit to carry debris away and reduce the recast layer.3. The general technical requirements for experimental system of JECM-LBM were summarized based on the analysis on the characteristics of JECM-LBM. The experimental system was developed by the general technical requirements, the results of research on the laser attenuation and laser-induced mechanical effect in the electrolyte. The jet equipment, the key component of the experimental system, was analyzed and optimum designed.4. According to the thermal-mechanical effect of laser and electrochemical effect of ECM, a two-dimension mathematical model for JECM-LBM was proposed based on the theory of temperature field and electric field. Based on the model, the shape of the machined holes by JECM-LBM was simulated by FEM software with the method of independent computing in time domain and superposition transform on boundaries. The simulation results have been verified by the experimental results. This modeling and experimental verification revealed the processing mechanism of JECM-LBM and laid the basis for the subsequent processing experimental research.5. Using the self-developed experimental system, JECM-LBM experiments were performed on stainless and nickel-based superalloy with nanosecond infrared laser and millisecond green laser. The experimental results were confirmed that JECM-LBM is feasible. Under the premise of maintaining a relatively high processing efficiency, the new hybrid process can reduce the thickness of recast layer to be less than 5μm, obtain high machining quality with none heat affected zone and better machining accuracy. The basic processing rules have been summarized by the comparison of the experimental results with different process parameters.The above theoretical analysis and experimental investigation were shown that JECM-LBM successfully combines laser beam machining and jet electrochemical machining and obtains the high machining quality & efficiency. The hybrid process has great potential as a new technical approach for the cooling holes in aeroengine hot components.更多还原