Study And Development Of CAPP Based On Manufacturing Resource Restriction

With the widespread use of CAD and the continuous improvement of NC machining technology, machinery manufacturing enterprises wish to achieve structure updating to obtain long term growth by establishing the advanced CIMS(Computer Integrated Manufacturing System).CAPP, as a significant module of the CAD/CAPP/CAM integrated system, is the information exchange center of the system, and links the integrated system and the enterprise environment. So information processing capability of CAPP decides the quality of the entire system. There is important and pressing practical significance to study the CAPP based on the CAPP/CAM integrated environment. Under this background, based on the actual demand of gear case manufacturing enterprise, the Computer Aided Process Planning which orients the box part and the integration of CAD/CAPP based on the manufacturing resource restriction, is developed and studied in this paper.The manufacturing resource are classified after the study of the need for manufacturing resource in the process of the manufacture and the process decision. And then the attributes of every kind of the resource are analyzed and inducted, the resource models are built. On the base of the resource models the manufacturing resource database is built and the management module of the manufacturing resource is developed. On the one hand, the management module can achieve the change of the enterprise's resource and the resource' processing capacity instantly. And then the resource' capacity is offered to the CAD module in the form of file to aid the designer to make more reasonable product design. The contradiction between the design and enterprise's process capacity will be found in time, and the design's manufacturability will be guaranteed. On the other hand, the management module offers the manufacturing resource restrictions to process decision to make the tasks such as process planning and the cutter tool selection be completed in the feasible field. So the generated manufacturing process's feasibility will be guaranteed.The feature-file is the information exchange interface of CAD/CAPP system. CAPP module achieves product information from the feature-file to make the process decision. As the prismatic part's process decision is made, the influence of casting technique to the roughcast is considered. The casting technique knowledge is referred to modify the roughcast and calculate the dimensions reasonably. After that, every manufacturing feature's rational roughcast dimensions are achieved, the feature-file of roughcast will be generated based on the part's feature-file. And then the roughcast's feature-file will be read by the CAD module to display and modify. So the previous CAD/CAPP integrated system can extend to the field of casting technique.The improved Genetic Algorithm is adopted to implement the multi-objective optimization to the process planning and machine tools selection by the lowest cost and the highest efficiency as the targets. Dual mutation mode is applied to reduce the amount of the iterative algorithm's computation, improve the optimization efficiency. After the process planning,the selection of tools and cutting data are accomplished, the tool paths of digital control processes are generated and the tool paths with the same cutter and clamp are connected to assist the CAM module in compiling the NC codes.