面向制造的并联机床精度设计

Manufacturing Oriented Tolerance Design of Parallel Machine Tools

精度设计是机床误差避免技术的重要手段，涉及在工作空间中给定刀具的最大位姿允差后，合理地制定零部件制造公差及装配工艺的问题。以３—ＨＳＳ型并联机床为对象，利用空间矢量链模型建立零部件制造误差与动平台位姿误差的映射关系。给定零部件制造公差后，利用该模型即可预估出动平台的位姿误差。在此基础上，根据灵敏度分析结果，提出一种在给定刀具位姿允差条件下，以零部件制造公差加权欧氏范数最大为目标，以角性公差和线性公差在同一精度等级下达到均衡为约束条件的精度设计方法。研究成果已成功地应用于一台并联机床样机的开发。

Tolerance design plays an important role in error avoidance of parallel machine tools, which is primarily concerned with determination of the manufacturing tolerances of components and subassemblies for the specified pose accuracy in the overall workspace. In this paper, the methodology for error analysis and synthesis of a 3 DOF parallel machine tool are investigated. The statistic model is formulated, which describes the mapping relationship between the manufacturing errors of components and the volumetric error of the platform. The sensitivity analysis is implemented to find the sensitive error sources. A new approach for determining the manufacturing tolerances is presented, which allows the angular and linear tolerances to be maximized and properly balanced with respect to the same manufacturing accuracy level. The results have been successfully applied to the development of a prototype machine.