基于运动学方法的线性尺寸定位误差通用建模与分析

定位误差是评价夹具性能的重要指标 ,分析定位误差是夹具设计中的一个重要环节。由于定位元件与工件的制造误差 ,工件安装后将不可避免地产生位置偏移 ,定位误差就是由于工件上的工序基准点位置在加工方向上发生偏移而引起的。现有夹具定位方案误差分析方法 ,如合成法、极限位置法以及微分法所建立的定位误差计算模型仅适用于特定类型的定位方案 ,不具备通用性 ;而目前利用运动学方法所建立的夹具模型仅考虑了定位接触点位置的影响 ,没有考虑调刀基准点位置偏移的影响。为此 ,根据运动学方法 ,在完善夹具模型的基础上 ,本文提出线性尺寸定位误差的通用模型与分析技术。

Generalized Modeling and Analysis Techniques of Fixture Locating Errors on Linear Dimensions Based on Kinematics

Locating error is a crucial index to evaluate fixture performances. Analyzing locating error is an important step of fixture design. Owing to manufacturing errors of locators and workpieces, the workpieces will inevitably shift with respect to its prescribed position after locating. Consequently, it is the displacement of process reference points on the workpiece that causes locating errors. Actual methods such as combination, extreme position and differentiation methods are available to modeling and analyzing locating errors, but they are limited to homologous fixture locating schemes. On the other hand, current fixture model using kinematics only takes into account the influence of contact points, and neglects the influence of tool-setting reference points. Therefore, by means of kinematics, the fixture model is firstly improved in this paper and then a generalized modeling and analysis techniques of fixture locating errors on linear dimensions model are presented.