Part Feature Obtaining And Process Sequencing Using Genetic Algorithm In 3D CAPP

Process planning is the bridge to link product design and manufacture. The CAPP system in 3D environment (3D-CAPP) is an important means to realize the quantitative and intelligent process planning. It has significant meaning to improve product research and development. According to the project supported by the 863 Program, two important technologies about 3D-CAPP, including part feature obtaining and process sequencing based on genetic algorithm, are studied. First, the framework of 3D-CAPP system is built up and the working flow of 3D-CAPP system is discussed. Several methods of CAD/CAPP integration, including neutral file based method, PDM based method, direct integration method, are compared. Secondly, the process describing method is given based on researches of the STEP standard, STEP files structure and EXPRESS modeling language. Via reading and analyzing the information in STEP files, the part feature identification and obtaining is realized. Then, taking a box part as an example, a process sequencing question using genetic algorithm (GA) is described. The mathematics model of process compositor using GA is built up, and the basic working process, including coding and decoding the working procedure, fitness function, crossover and mutation, is put forward. Then this method is used is the process sequencing of a box part. A prototype of 3D-CAPP system has been developed. Some primary functions of this system are described. Finally the work is summarized and further research is pointed out.