纳米级精度的竖直液体静压滑台设计

为了满足航天关键件的加工精度要求,需要设计并制造满足设计要求的纳米级精度的竖直液体静压滑台。本文针对滑台结构、关键部件及公差设计方法展开了研究。首先,根据高精度竖直滑台的设计要求,采用不等流量的滑块结构及控制方法整体设计滑台结构。设计时,将所有液压油管路均设置在滑块中,以减小油压损耗,且使得滑台结构紧凑。接着,为使圆孔加工时圆度误差不受导轨刚度的影响,采用等导轨刚度的设计方法,同时给出了该方法下油膜厚度、刚度、压力的计算方法。文中还证明了上下油腔不等承载面积法能够降低竖直滑台由于倾覆力矩产生的倾角误差,提高导轨运动精度。在此基础上,提出了基于不等流量结构的几何精度设计方法,计算并证明了不等流量的结构和控制方法可以降低导轨和滑块极高的制造等级要求和制造成本。最后,根据上述设计方法设计并制造了数控纳米曲面磨床竖直滑台,并测试了该磨床竖直Z滑台的运动精度。结果显示采用不等流量结构的滑台制造公差要求由IT1降低到IT3。Z滑台精度测试结果为:定位误差为±80nm,重复定位误差为48nm。

Design for vertical liquid hydrostatic slide with nano-scale precision

In order to satisfy maching accuracy requirements for aerospace key parts, this paper designed and formulated a vertical liquid hydrostatic slide with nano-scale precision.The research was carried out from aspects of slide structure, key parts and tolerance design method of slide.Firstly, according to the design requirements for vertical slide with super-precision, unequal flow structure and control method was introduced to realize overall design of slide structure.In this scheme, all liquid hydraulic oil lines were in slide with compact structure, which could reduce loss of oil pressure.Then, in order to guarantee that roundness error at the time of processing for round hole was not affected by guideway stiffness, the design method of equal guideway stiffness was presented.Meanwhile,calculation methods for thickness, rigidity and pressure of oil film were derived.It was proposed and proven that unequal bearing area method for up and down oil chamber could decline inclination error of vertical slide caused by overturning moment, thus could improve movement precision of guideway.On this basis, design method for geometric accuracy based on unequal flow structure was proposed, and it was proven that this proposed structure and control method could decline extremely high requirements for manufacturing level and manufacturing cost of guideway and slide.Finally, vertical slide for hook face grinder of CNC nano was designed and manufactured according to the above design method, and movement precision for vertical Z slide of the grinder was tested.It is concluded that requirement for manufacturing tolerance of slide with unequal flow structure declines from IT1 to IT3, and unequal bearing area makes the slide back 0.3μm.Test result for Z slide precision is: position error is ±80nm, and repeated position error is 48 nm.