液体静压主轴零件磨削的形位误差传递机理及精度循环递升方法

With the tendency of rotational error of hydrostatic spindles becoming smaller and smaller, the effect of geometrical error of spindle workpieces on rotational error of spindles are significant. How to minimize the workpieces geometrical error is very important for upgrading precision. However, in precision grinding processes of workpieces of hydrostatic spindles, the mechanism of the geometrical errors coming into being in the complex grinding system and the corresponding principles are not clear. How to upgrade the precision of workpieces, spindles and grinders continuously, and exhaust the precision potential based on the mechanism and principles ? So far, the problems have not been satisfactorily solved on science nature level. A method of cycle-upgrading precision of spindles and grinders based on all hydrostatic spindles are proposed. Research approach of modeling and analyzing dynamic charateristics of grinding system based on the spindle rotational error and the workpieces geometrical error are provided. The theory system of geometrical error transmission of grinding workpiecess of hydrostatic spindles will be established in the project. Rotational error of hydrostatic spindles and geometrical error of the workpieces of grinding systems will be quantitatively simulated. The effects of the spindle rotational error and grinding system parameters on the geometrical error of the workpieces will be revealed. Specific strategies of cycle-upgrading hydrostatic spindle rotational precision and grinder precision will be proposed. Theoretical and technical support for developing advanced ultra-precision machine tools will be provided.

在液体静压主轴回转误差越来越趋于极小化的情况下，零件形位误差对回转精度的影响已逐步凸现。如何最大限度地降低零件形位误差已成为挖掘精度潜力的关键。但是在零件精密磨削过程中，形位误差是如何在复杂的磨削工艺系统内部传递的，其形成机理和定量规律一直不明确。如何根据这些机理和规律，在现有主轴精度和机床精度条件下，持续提升零件、部件和机床精度，穷尽精度潜力等问题，迄今未在科学本质层面圆满解决。本项目提出了基于完全液体静压主轴部件的磨床精度循环递升方法，以及将主轴回转误差和工件形位误差统一于磨削工艺系统动力学研究的新思路。项目将建立液体静压主轴零件磨削形位误差传递理论体系，实现磨削工艺系统主轴回转误差和工件形位误差的定量仿真，揭示主轴回转误差和磨削系统参数对工件形位误差的影响规律，提出液体静压主轴回转精度和磨床精度循环递升的具体途径，为研制开发国际前沿水平的超精密机床提供理论和技术支撑。

本项目从磨削系统动力学和磨削工艺优化等角度，建立了液体静压主轴磨削工件形位误差传递机理及精度循环递升方法的理论体系。针对超精密液体静压主轴的核心零件主轴和轴承在磨削过程中的圆度误差形成过程，建立了计入砂轮主轴回转误差、工件主轴回转误差和零件圆度误差的双转子磨削工艺系统耦合动力学模型。该模型基于有限元和铁木辛柯梁理论，针对双转子磨削系统动力学模型中磨削力与磨削参数和圆度误差相互耦合的特点，通过整体组装单元质量矩阵、刚度矩阵、陀螺矩阵和阻尼矩阵，采用数值积分法提出了基于磨削力-磨削变形量循环迭代收敛的磨削成型过渡过程仿真算法，定量模拟了磨削过程中零件形状误差的形成过程。揭示了典型磨削工况条件下砂轮主轴转速、工件主轴转速、磨削深度、磨削进给速度、主轴初始形位误差、动不平衡和回转精度等对工件磨削圆度误差形成的影响规律，提出了降低工件形位误差的有效途径。研究了磨削工件精度、主轴部件精度和磨床精度的循环递升规律，提出了零件加工精度最优化的具体策略及“零件—主轴部件—磨床”精度循环递升的评判依据和具体途径。搭建了主轴外圆磨削和静压轴承内孔磨削实验台并开展了系统的磨削工艺试验，通过对比理论计算值与实验测量值发现：理论计算值和实验测量值之间的相对误差均小于20%，证实了所提出的耦合模型、仿真算法和研究结论的合理性和有效性。 .本项目研究成果“极端工况液体静压（电）主轴及转台关键技术与应用”，获2016年教育部科技进步奖二等奖；研究成果“高速精密机床主轴轴承磨削关键技术及应用”获2018年机械工业科学技术奖二等奖。本项目研究揭示的磨削成圆规律和工艺方法在湖南大学和广州市昊志机电股份公司联合开发的6款超精密液体静压电主轴研制过程中成功应用，磨削主轴轴颈圆度优于0.2μm，装配完成的静压主轴回转精度优于0.1μm；该成果通过了2019年广东省机械工业质量管理协会组织的技术评审, 评价委员会一致认为整体技术达到“国际先进水平”。