超高速精密微主轴刀具动态误差分析及其控制方法研究

Micro-cutting and micro-grinding technologies with micro-machine tools have incomparable advantage in the production of geometrically complex 3D miniature components in a wide range of engineering materials. But the tool motion error of micro-spindles currently developed is quite large at ultra-high speeds, which seriously affects machining quality and machining efficiency of micro-machine tools. This project proposes the control methods including advance error evaluation with the combination of static and dynamic states and on-line compensation, and corresponding theory for dynamic error of the tool of ultra-high speed and precision micro-spindle, in order to break the technological bottleneck of submicron error motion of the micro-spindle at ultra-high speeds and effectively resolve the problem of its poor machining quality at ultra-high speeds. It will study stiffness transfer rule and dynamic characteristics of the micro-spindle system and establish stiffness chain model and relation model between cutting parameters and tool tip displacement, which can provide a basis for error evaluation of the micro-spindle at static and dynamic states. It will study various factors that influence the error motion of the tool at ultra-high speeds and reveal the variation laws of motion error with rotational speed, load and time, which can provide technical support for on-line tool dynamic error compensation. Based on above study, it will establish the control methods and corresponding theory for dynamic error of the tool of ultra-high speed and precision micro-spindle, so as to provide theoretical basis and lay solid foundation for the research of micro-cutting equipment and process of our country. This project has strong theoretic significance and practical value.

采用微机床的微细切削磨削加工技术在复杂形状三维微小零件加工方面具有无可比拟的优势。但是目前研制的微主轴在超高速回转时刀具的跳动误差很大，严重影响了微机床的加工质量和效率。本项目提出结合静动态误差预估方法与刀具跳动误差在位补偿技术的超高速精密微主轴刀具动态误差控制方法及理论，突破微主轴超高转速下刀具亚微米跳动的技术瓶颈，有效解决微主轴超高转速时加工质量低的问题。研究微主轴系统刚度传递规律及动力学特性，建立系统刚度链模型及切削参数与刀尖位移量之间的关系模型，为静态与动态下误差的预估提供理论依据；研究超高转速下刀具跳动误差的各种影响因素，揭示刀具跳动误差随转速、载荷、时间的变化规律，为在位补偿其跳动误差提供技术支持；在上述研究基础上，最终建立超高速精密微主轴刀具动态误差的控制方法及理论，为我国微细切削加工装备及工艺研究提供理论依据并打下坚实的基础。本研究具有很强的理论意义和实用价值。

采用微机床的微细切削磨削加工技术在复杂形状三维微小零件加工方面具有无可比拟的优势。但是目前研制的微主轴在超高速回转时刀具的跳动误差很大，严重影响了微机床的加工质量和效率。本项目提出静、动态误差预估与综合误差在位补偿控制技术以及新型的气动微涡轮驱动、多孔质气体静压轴承支承的微主轴结构，旨在突破微主轴超高转速下刀具亚微米跳动的技术瓶颈，有效解决微主轴超高转速时加工质量低的问题。深入研究了微主轴—刀具系统各零部件的刚度特性，揭示了刀尖热误差以及刀尖跳动误差随加工时间、刀具悬长、主轴转速的变化规律，建立了微主轴转子—夹头—刀具系统的刚度链模型和刀尖综合误差补偿模型；深入研究了冲击式气动微涡轮、多孔质气体静压轴承等关键部件的设计理论，重点得出了微主轴切削受载时的静态误差和动力学响应特性的理论模型，建立了新型微主轴的设计理论和方法；研制了超高速精密微主轴样机2台，其外部结构尺寸Ø28mm×长49mm，最高转速达300000r/min；应用上述成果构建了微细机械加工试验台，微细磨削试验结果表明磨头尖端的径向误差由原来的5.6µm减小到0.7µm，验证了本项目技术成果的可行性和有效性。本项目所开发的微主轴结构简单，在现有一般加工条件下就可实现较大技术水平突破，降低了制造难度及成本，有利于微主轴的市场化开发及应用。因此本项目研究成果为我国微主轴、微机床和微细切削磨削加工技术的研究提供了很好的技术支撑。