A database realization method to product information model based on STEP

Product data exchange and interfacing between different CAD/CAM systems are very important to the development of concurrent integrated design. In this paper, an integrated STEP-based production information model for mechanical systems is presented. First, an architecture of this system is established using a three-layer architecture (application, logic and physical layers) recommended by STEP, and an information model using database implementation approach is defined using STEP's EXPRESS language. This model includes GIM (general information model), SIM (structure information model), SCM (shape construction model), PFM (physical feature model), and MIM (management information model). Then, the database implementation method to information model is analyzed thoroughly, which include how to build data dictionary, how to transfer EXPRESS entity to base table in relational database and how to access product data in database. The information model and its application can make heterogeneous CAD system integration more convenient.