液体静压运动副的四轴联动精密加工机床结构设计

Structure design of four-axis linkage precision machine tool for hydrostatic motion pair

大口径平面、球面、非球面光学元件广泛应用于光刻机、高能激光器、高分相机等高端装备的光学系统中,尺寸大于400 mm×400 mm、表面轮廓精度均方根值(root mean square,RMS)优于1μm等技术指标是大口径光学元件在磨削加工阶段的目标精度要求。磨削工艺主要面临如何实现高平滑的表面轮廓加工以及控制亚表面损伤层深度等问题。根据已有的实验研究,磨削机床采用高精度的液体静压运动副,可以有效地提高光学元件抛光后表面轮廓的平滑程度以及降低亚表面损伤层的厚度。具备上述特性的高性能磨削机床国外对中国禁运,而国内尚无成熟的商品。因此,文章研制了一种采用液体静压运动副的四轴联动精密加工机床,分析了机床的主要构型,进行了机床主要运动部件的精度分配,完成了基于液体静压运动副的X/Y/Z/C四轴的设计方案,最后进行了光学元件磨削加工工艺实验,实现了380 mm×541 mm口径微晶玻璃磨削面形精度±0.471μm(RMS值)、表面粗糙度Ra0.3μm的加工目标。

Large aperture planar,spherical and aspherical optical components are widely used in optical systems of lithography machine,high energy lasers,high resolution cameras and other high-end equipment.In the grinding stage of large aperture optical components,the size≥400 mm×400 mm,surface profile accuracy Root Mean Square(RMS)≤1μm are the key technical indicators.The main problems in grinding process are high smooth surface profile machining and depth control of sub-surface damage layer.According to the available results,the high precision hydrostatic motion pair is used in grinding machine,which can effectively improve the smoothness of the surface profile and reduce the thickness of the sub-surface damage layer after polishing the optical element.High-performance grinding machines with the above characteristics are prohibited to China abroad,and there are no mature products in China.In this paper,a four-axis linkage precision machining machine tool with hydrostatic motion pair is developed.The main configuration of the machine tool is analyzed.The precision distribution for the main moving parts of the machine tool is carried out.The design scheme of the X/Y/Z/C four axis based on the hydrostatic motion pair has been completed.Finally,experiments on the grinding process of optical components were conducted.For the 380 mm×541 mm size microcrystalline glass,the surface shape accuracy and surface roughness reached±0.471μm and Ra 0.3μm,respectively.