Developing Feature-based Manufacturing Applications Using PDES/STEP

Abstract

This paper provides an object-onented approach to implement the PDES/STEP-based information model for concurrent engin eering applications. The PDES/STEP-based information model is the global foundation of concurrent engineering communication. To demonstrate the approach, a schema for assembly operations is defined, using the EXPRESS language, in the form of a prototype data model. The assembly_model entity is designed to carry the assembly system configuration information: bill of material (BOM) and assembly sequence. The assembly entities, called joints, are designed to work with each component part's PDES/STEP geometry, form feature, and tolerance definition. The connectivity of each joint is directly related to mating or joining parts' assembly-related form features. Examples are given to illustrate the use of PDES/STEP entities to construct the feature- based part definition and proposed assembly schema. The assembly schema is translated into the classes that both C++ and ROSE (an object-oriented database designed to support concurrent engineering and work with PDES/STEP) can accept. The classes serve as object templates for both application programs and ROSE, which has the capability to output the object in a STEP file format. The assembly functions and constraints related to the assembly entities are also defined to represent the dynamic properties of assembly schema.