Research On Automatic Dimensioning For 3D Parts Based On Feature Modeling

With the development of digital product definition technology,full-digital product definition represented by MBD(Model Based Definition)has gradually become the trend of product definition.That promotes the development of 3D dimensioning technology which is more intuitive than 2D dimensioning.But the traditional way of dimensioning consumes a lot of manpower and time costs,which immaterially reduces the efficiency of product design and production.It is of great research significance to realize rapid dimensioning of 3D dimension,and to ensure that the dimension data are complete and conform to the labeling rules.There are two kinds of research route to research automatic dimensioning for 3D model,the one is based on feature model,and the other is based on geometric model.The dimension results of the first way meet the engineering requirements,but its Correctness is limited by the development of feature recognition technology.The second way is easier to get dimension of 3D models,but its dimensioning results are lack of the practical engineering mean.So this paper combine two research routes to research automatic dimensioning for 3D model,this article develop 3D dimensioning and layout function which is based on feature modeling process on UG software.In this article,two different ways are used to realize the dimensioning of 3D model.For features which are isomorphic,such as rounded corners,chamfers,holes and arrays,dimension is labeled by treating feature as a whole,and feature dimension is labeled in fixed mode according to engineering labeling standards,so as to ensure the rationality of dimension labeling.For the rest feature surfaces,the feature surface is taken as the basic unit of dimension labeling.The labeling elements are extracted from each feature surface and grouped,and the dimension labeling sets are divided according to the grouping results,so as to realize t shaping and positioning all feature surfaces,to ensure the integrity of dimension labeling.At the same time,combined with the partition of dimension set in automatic dimension extraction process,reasonable dimension plane and location are selected for dimension of different dimension elements set,and dimension layout is carried out to prevent dimension interference and realize dimension automatic marking of three-dimensional parts.Based on Visual Studio 2010 and UG/OPEN API,the automatic dimensioning function of 3D parts is developed in UG 8.5 with C# programming language and examples are given to show the practical effect of the automatic dimensioning algorithm.