大气等离子体射流加工的热误差在线补偿方法

Online Compensation Method of Thermal Error in Atmospheric-pressure Plasma Jet Machining

大气等离子体射流加工由于其化学刻蚀的加工原理,材料去除速率极易受温度影响,然而加工区域内温度波动造成的面形误差目前仍难以有效预测与抑制。为了补偿大气离子体射流加工中热效应引起的非线性加工误差,搭建了可在线测量加工区域温度的大气等离子体射流加工系统,分析了加工过程中全局和局部热效应对材料去除速率的影响规律,建立了考虑热效应的时变非线性去除函数模型及标定方法,依据加工区域温度的实时测量数据,实现了基于驻留时间动态调整的大气等离子体射流加工热误差在线补偿技术。熔石英光学元件的修形加工实验结果表明,所提出的方法有效补偿了加工过程中由温度波动引起的面形误差,材料去除量误差PV从362.71 nm降低至132.25 nm,提升63.54%,RMS从90.02 nm降低至33.45 nm,提升62.84%。研究结果为提升大气等离子体加工的修形精度提供了新的思路与参考。

Due to the chemical etching principle of atmospheric-pressure plasma jet(APPJ)machining,the material removal rate is highly susceptible to temperature fluctuations.However,the surface residual errors caused by temperature fluctuations during the machining process are still difficult to predict and suppress.To compensate the nonlinear errors caused by thermal effects,an APPJ machining system capable of online measuring the temperature in the processing area is established.The influence of global and local thermal effects on the material removal rate during the processing is analyzed,and a time-varying nonlinear removal function model and calibration method considering thermal effects are established.Based on real-time measurement data of temperature in the processing area,an online compensation method for thermal errors in the APPJ machining based on dwell time adjustment is proposed.The experimental results of figuring fused quartz optical elements show that the proposed method effectively compensates for the surface residual errors caused by temperature fluctuations during processing.The PV of residual errors is reduced from 362.71 nm to 132.25 nm with an improvement of 63.54%,the RMS is reduced from 90.02 nm to 33.45 nm with an improvement of 62.84%.The results provide new ideas and references for improving the figuring accuracy of APPJ machining.