随机磨损影响下多轴机床加工精度保持性预测及稳健设计

Accuracy retaining ability is the core performance and a very important technical indicator to evaluate the working performance of NC machine tools. So, how to improve the retaining ability of machining accuracy is one of the technical bottlenecks of the research and development of high-grade precision machine tool. The project aims to predict the machining accuracy retaining ability and resolve the robust optimization design problem, with consideration of the stochastic and time-varying characteristics of guide and ball screw under complex loading conditions and time course. In the project, the influence of random wear of the guide and ball screw pairs to the geometric accuracy and motion accuracy of machine tools will be revealed, the time-varying prediction model of the machining accuracy retaining ability with considering of the relevance of different loss models of machining accuracy will be established; based on the global sensitivity analysis, the random error sources and accuracy loss model correlation influence on machining accuracy will be investigated, the robust optimal distribution model for machining accuracy retaining ability will be established, and the method of machining accuracy retaining ability prediction and robust optimization design for multi-axis machine tool will be proposed systematically. A specific machine tool product will be selected to validate the proposed method. The project can provide theory and method support for the accuracy design and inversion of high precision machine tools, reasonable distribution of accuracy grade of key parts, and is of important theoretical and practical significance to the independent research and development and technological innovation of high precision NC machine tools in China.

精度保持性是机床的核心性能，是衡量数控机床工作性能非常重要的技术指标，如何提升加工精度的保持性更是制约我国高档高精度机床研发的技术瓶颈之一。项目考虑导轨副与丝杠副在复杂载荷环境和时间历程下磨损的随机性与时变性，研究加工精度保持性预测及稳健优化设计问题；揭示导轨副与丝杠副的随机磨损对机床几何精度与运动精度时变衰退的影响规律，考虑加工精度不同丧失模式的相关性并建立多轴机床加工精度保持度的时变预测模型，基于全局敏感度分析探讨随机误差源及加工精度丧失模式相关性对加工精度保持性的反向影响趋势，建立面向加工精度保持性的机床稳健优配模型，系统提出多轴机床加工精度保持性预测与稳健优化设计方法，并结合具体的产品进行实验验证。项目的研究为高档精密数控机床的精度设计与精度反演及优配、合理确定多轴机床各环节的精度等级提供理论与方法支持，对我国高档精密数控机床自主研发与技术创新具有重要的理论与实际意义。

精度保持性是机床的核心性能，是衡量数控机床工作性能非常重要的技术指标，如何提升加工精度的保持性更是制约我国高档高精度机床研发的技术瓶颈之一。项目考虑导轨副与丝杠副在复杂负载与进给速度等工况和时间历程下磨损的随机性与时变性，研究加工精度保持性预测及稳健优化设计问题。针对导轨副与丝杠副的精度衰退及预测研究主要包括：采用准连续介质原理的多尺度判定方法，实现了对导轨时变工况下磨损导致直线精度损失过程的描述；基于Archard磨损理论，提出并建立了滚珠丝杠副复杂工况动态波动因素下的磨损数学模型，并对时变工况下的精度衰退进行了预测。针对数控机床加工精度保持性预测及稳健优化设计主要展开以下研究：分析影响数控机床加工精度的主要误差源关联到数控机床综合误差预测中，建立了一个包含几何误差﹑主轴热误差和磨损引起的刀具几何误差的数控机床加工精度模型，实现了面向多误差源的数控机床加工精度预测；建立了基本变量服从任意分布的数控机床加工精度可靠性模型和可靠性敏感度模型，实现了基本变量服从任意分布的数控机床加工精度可靠性分析和可靠性敏感度分析；将可靠性理论从面向几何误差的数控机床精度设计领域拓展到面向多误差源的数控机床动态精度设计领域，解决了任意时刻误差参数变量服从任意分布的数控机床可靠性稳健设计问题，形成了一套面向多轴机床加工精度保持性的共性设计方法。系统提出多轴机床加工精度保持性预测与稳健优化设计方法，并结合五轴数控立式加工中心XKH800产品进行实验验证。项目的研究为高档精密数控机床的精度设计与精度反演及优配、合理确定多轴机床各环节的精度等级提供理论与方法支持，对我国高档精密数控机床自主研发与技术创新具有重要的理论与实际意义。