A Method of Parametric Model Data Exchange and Reconstruction Based on Feature Script

Abstract

Abstract In collaborative product development (CPD), iterative design with heterogeneous CAD systems is always completed by original equipment manufacturers (OEMs) and other suppliers around the world. Therefore, product data exchanges among different heterogeneous CAD systems are crucial in CPD. However, the major bottleneck is that parametric part models of complex products cannot be exchanged among heterogeneous CAD systems. Published by the International Organization for Standardization (ISO), the Standard for the Exchange of Product Model Data (STEP) is the most common solution for geometry-based data exchanges and product annotations in the manufacturing industry. However, the exchanged STEP parts cannot be modified due to the loss of important information including modeling history, parameters and constraints, which involve the design intent. Therefore, the challenge of modification on exchanged parts needs to be overcome for iterative design in heterogeneous CAD systems of the manufacturing industry. In this paper, a method of part parametric model data exchange and reconstruction based on feature script is proposed. The main idea is features, which include reference features (like datum-plane, datum-axis, and datum-point), shape features (like extrude and rotation), auxiliary features (like fillet and chamfer), and sketch features. These features are taken as the fundamental elements of a part in CAD system, and each is defined by feature script and saved as an extensible markup language (XML) node. The feature modeling history of a part is regarded as a tree structure, which can be converted to an XML tree structure. In part model reconstruction, the proposed method utilizes a persistent naming mechanism and geometric data to identify topological entities, and then realize the persistence of constraint information and parameter driving of part model. The proposed method will be applied to part data exchange and parametric model reconstruction among heterogeneous CAD systems in the following process: (i) the feature tree and parameters of the parametric model are obtained in the source CAD system; (ii) the feature model data is translated into feature script and saved as XML format file; (iii) the feature script file is read, and the parametric model is reconstructed in the target CAD system according to modeling history. In order to verify the accuracy of data exchange and model reconstruction between Creo and CATIA, a method on constraints equivalence analysis and feature comparison is also proposed for analyzing the similarities and differences between source and target parametric models. In addition, a case study is presented to demonstrate the potentials of the proposed method for parametric-feature model exchanges among heterogeneous CAD systems in web-based collaborative product development.