超声振动辅助激光抛光加工理论及实验研究

Laser polishing can achieve precise polishing of complex surfaces. It not only has the selective polishing speed and friendly environment, but also is a non-contact way to avoid tool wear. Based on traditional laser polishing, the energy distribution on the focus point of laser beam is changed by changing the frequency and amplitude of ultrasonic vibration lens, so that the surface quality of the workpiece after ultrasonic vibration assisted laser polished is better than that of the surface after traditional laser polished in this project. A model of ultrasonic vibration assisted laser polishing process and traditional laser polishing process will be established, and the above processes will be simulated by using open source CFD software and experiment calibration accurately, then the frequency and amplitude in ultrasonic vibration laser polishing process will be optimized, and the ultrasonic vibration setup will be designed, manufactured and tested. A large number of experiments will be done to prove the theory of ultrasonic vibration assisted laser polishing using aluminum alloy, titanium alloy, stainless steel, quartz glass and so on, and the parameters of ultrasonic vibration assisted laser polishing will be optimized. In addition, the workpiece surfaces after ultrasonic vibration assisted laser polished, traditional laser polished and the originals will be analyzed and compared on hardness, corrosion resistance, friction coefficient and section structure and so on in order to optimize the polishing parameters further, it will enrich and perfect the theory of laser polishing, which will play an active role in the promotion and application of laser polishing technology.

激光抛光可实现复杂型面的精密抛光，不仅具有可选择的抛光速度、环境友好，而且是一种非接触方式，避免刀具磨损。本项目在普通激光抛光基础上，通过控制透镜的超声振动频率和振幅来改变激光聚焦焦点处能量分布，从而使抛光后的工件表面质量比普通激光抛光后的工件表面质量更好。项目将对超声振动辅助激光抛光过程和普通激光抛光过程建立数学模型，并利用开源CFD（计算流体动力学）软件和实验标定进行仿真，优化超声振动频率和振幅，设计制造并测试超声振动辅助装置。在此基础上，对铝合金、钛合金、不锈钢、石英玻璃等材料进行超声振动辅助激光抛光实验，来验证超声振动辅助激光抛光理论并对激光抛光参数进行优化。另外，将超声振动透镜辅助激光抛光工件、普通激光抛光工件和原工件表面硬度、抗腐蚀性、摩擦系数和剖面组织结构等进行分析对比，进一步优化超声振动辅助激光抛光参数，丰富和完善激光抛光技术理论，为激光抛光技术的推广应用起到积极推动作用。

近年来，超声振动辅助加工与各种先进制造方法相结合形成新的复合加工技术，复合后的加工技术可以实现更加理想的加工效果，因此被国内外学者们广泛关注。激光抛光是一种新兴的表面处理技术，与传统抛光方法相比，具有非接触、效率高、不受材料限制、加工灵活性高以及环保无污染等特性，被应用于模具、3D打印件、光学元件、半导体器件等。本项目将透镜超声振动与激光抛光相结合，提出了超声振动辅助激光抛光技术，用于进一步提高激光抛光后的表面质量。. 本项目深入研究了透镜超声振动辅助激光抛光的加工机理，设计并搭建了透镜超声振动辅助激光抛光试验系统，使用COMSOL有限元分析软件对激光抛光过程进行了数值模拟，分析了透镜超声振动对激光抛光过程的影响机制，采用多维度指标对超声振动辅助激光抛光的表面质量进行了综合的评价。在透镜超声振动的作用下工件表面的光斑半径将发生周期性变化，会改变工件表面激光能量的分布。阐明了在透镜超声振动作用下将传统的激光抛光过程转变为间歇式激光抛光过程，为透镜超声振动辅助激光抛光304不锈钢提供了理论基础。根据正交试验的极差分析与方差分析获得了透镜超声振动辅助激光抛光304不锈钢材料的最佳工艺参数组合，在此加工参数条件下表面粗糙度可降低81%。通过对激光抛光形成的熔池形貌分析可知，在透镜超声振动作用下将使工件表面的激光能量发生周期性变化，减少了激光能量在工件表面的积累。熔池横截面的微观组织分析表明，在适当的透镜超声振动参数作用下熔池内晶粒可以被细化。通过本项目相关研究工作可有力推动超声振动辅助激光加工技术的推广与产业化应用。

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