基于UG的三维装配尺寸面链表组自动生成方法研究

Automatic generation of 3D assembly feature surface chain groups associate to dimension based on UG platform

针对目前装配尺寸链不能实现真正意义上的自动生成及在装配尺寸链中很少考虑几何要素的几何公差的问题,提出了一种基于几何要素控制点理论公差表示模型的三维装配尺寸面链表组自动生成方法。在分析装配公差建模的信息组成的基础上,建立了装配公差信息的计算机储存储数据混合图结构。以UG NX7.5为二次开发平台,提取了三维装配体内零件上尺寸公差、几何公差、装配基准以及装配目标等信息。首先,确定了封闭环;然后,根据建立装配尺寸链的最短路径的原则搜索装配公差信息图,建立了三维装配尺寸面链表;最后,根据装配顺序及设计基准将其按零件拆分为三维装配尺寸面链表组。以三正交平面作为装配基准的轴孔装配为例,对该方法进行了验证。研究结果表明,该方法能够综合考虑几何要素的尺寸和几何公差,为后续的公差分析工作打下坚实的基础。

Aiming at the problems that assembly dimension chain couldn＇t generate automatically in real sense and rarely considered geometric tolerance in the current, a method for the automatic generation of 3D assembly feature surface chain groups associate to the dimension was proposed based on the theory of tolerance model representing by control points of geometric elements. According to the information requirement of the assembly tolerance modeling, the data structure of a mixed graph stored by computer for assembly tolerance information modeling was established. On the platform of UG NX7.5 OPEN, the assembly information, such as the dimension and geometry tolerance, geometry structure data, the assembly datum and target information, were removed from the feature model of the assembly and parts. Firstly, the closed loop was determined, and then the 3D assembly feature surface chain associate to the dimension was constructed by searching the assembly tolerance information graph according to the rule of shortest path of establishing assembly dimension chain. Finally, it was broken into 3D assembly feature surface chain groups associate of the dimension one of which just belong to one part of the assembly based on the assembly sequence and design datum. At last,the method was verified by the pin-hole assembly with three orthogonal planar assembly data. The results indicate that dimensions and geometric tolerances are taken into account and a solid foundation is laid for the subsequent tolerance analysis.