全气体静压环形抛光机床的研制及应用

Development and application of full gas hydrostatic ring polishing machine

针对单轴抛光机面形控制难度大、较多依赖人工经验,无法满足光学元件激增的数量和精度需求的问题,提出研制一种新型超精密环形抛光机床。首先引入抛光盘跳动为变量构建基于Preston公式和赫兹接触理论的材料去除模型;模型仿真分析表明抛光盘跳动误差变化会导致材料不均匀去除,而主轴跳动误差和导轨直线误差会直接影响抛光盘的面形修正和测量精度。然后基于此结论,利用静态、模态、谐响应分析对机床整体布局和横梁支撑形式进行优化;同时设计气体静压导轨和主轴以提高直线运动精度和主轴回转精度。最后为了验证机床精度和加工指标,采用LK-G5000激光传感器检测导轨和转台的运动误差分别优于1.2μm/400 mm和0.4μm。对φ300 mm的UBK7光学元件进行抛光,8小时后粗糙度和PV值分别优于R_(a)0.56 nm和1/10λ。结果表明:所研制的超精密环形抛光机床达到了设计要求。

Considering key challenges that include controlling the surface shape of a single-axis polishing machine,greater reliance on manual experience,and the necessity to meet demands such as the increasing number and precision of optical elements,a new ultra-precision ring polishing machine is proposed.First,a material removal model based on the Preston formula and Hertz contact theory was constructed by intro⁃ducing the thrown disc runout as variable.Model simulation analysis shows that runout error variation leads to uneven removal of materials,and that the runout error of the spindle and the linear error of the guide rail will directly affect the surface shape correction and measurement accuracy of the disc.Based on this conclusion,the machine tool overall layout and beam support form were optimized using static,modal and harmonic response analysis.At the same time,the hydrostatic guide rail and spindle were designed to improve linear motion and spindle rotation accuracy.Finally,to verify the machine tool accuracy and ma⁃chining index,the motion errors of the guide rail and turntable are better than 1.2μm/400 mm and 0.4μm,respectively,using the LK-G5000 laser sensor.φ300 mm UBK7 optical element in polishing,roughness and PV value superior to eight hours after R_(a)0.56 nm and 1/10λ.Finally,the results demon⁃strate that the proposed ultra-precision ring polishing machine meets design requirements.