Research On Decision Of Process Route And Cutting Parameters In Intelligent CAPP Systems

The process design is an important basic work in mechanical manufacturing industry and the bridge which connects the product design and the product manufacturing and an empirical decision-making process which varies with the manufacturing environment. The configuration and optimization of enterprise manufacturing resources and the product quality and cost and the production efficiency are influenced directly by the quality and efficiency of process design. At present, products are upgraded frequently and the enterprises have to produce a large variety of products in little batch sizes with the fast development of manufacturing industry. There are a lot of shortcomings of traditional process design such as poor consistency, inefficiency and it is difficult to ensure correct data. Early CAPP expert systems put one-sided emphasis on automation decisions and the knowledge acquisition is very difficult and the reasoning method is simple. It can be seen that traditional process design and early CAPP expert systems are unable to meet the development needs of modern manufacturing industry. This paper presents related research and exploration on such issues based on research results of artificial intelligence especially computational intelligence technology. The main research content and achievements are as follows.1. The overall frame of an intelligent CAPP system based on knowledge is set up on the analysis of shortcomings of traditional CAPP expert systems. The system composition and the information transmission are analyzed and the implementation and related technologies of the function of its sections are studied from multiple perspectives.2. According to the characteristics of representation method of knowledge frame and object-oriented, an approach of knowledge representation based on part feature is introduced on the basis of the feature-based modeling technology. The part feature information is divided into three layers, namely, feature cell, operation cell, cutting cell. Then the part feature information is described structurally by using XML language and the knowledge base of part feature information is built in this way.3. Based on the improved ant colony algorithm, an algorithm is put forward for the process route optimization to solve the decision-making problems of the process route in a intelligent CAPP system. First each part was divided into some feature cells, and the operation cells were generated by machining chains of feature cells. The similarity of every two operation cells was represented by the weighted Hamming distance between them on the basis of their properties. According to the constraints of the operation cells,the preference sequences of the operation cells can be determined, and the fore cells of each operation cell can be obtained and were stored in the fore tables. The validity of calculations will be ensured and the efficiency will be promoted. A process route was generated and optimized under the control of the tabu criterion and constraints.4. Based on the Pareto genetic algorithm, an algorithm based on a solving mode of optimization before decision is proposed for the cutting parameters selection and optimization to solve the decision-making problems of the cutting parameters in a intelligent CAPP system. First, a muti-objective model was built by analysis of restraint with cutting speed and feed as optimization variables and cutting efficiency and the tool life as optimization objectives. Second, the selection operator was improved. The fitness of individuals which fail to meet the constraint requirements equal to zero.In order to ensure the search direction, a non-inferior set was set up to save Pareto optimal solutions which were generated by competition during evolutionary processes. The crowing mechanism based on niche technology was established to keep population diversity. And then, genes were recombined by means of mixed crossover operator and step-size mutation operator and an optimal set which distributed uniformly along the Pareto front was obtained after a few times iteration.According to the theoretical studies above, this paper which takes the ERP system of TDNC corporation as the background introduces the development of a CAPP system based on computational intelligence technology by using the 3-tiered architecture based on the Browser/Server model.