Research And Implementation Of CAPP Expert System For Sheet Metal Distribution Box

With the rapid development of industrial automation,sheet metal manufacturing industry is facing a huge impact.Although many enterprises in sheet metal manufacturing market purchase many kinds of advanced manufacturing machinery,the mechanization and automation of production process are still low.In this paper,for the flexible manufacturing system,the group technology is used to analyze the parts of the sheet metal distribution box,and the expert system is used to realize the auxiliary design,automatic modeling and process decision-making functions according to the knowledge in the knowledge base,which can effectively improve the production efficiency and meet the actual needs of the enterprise.The main contents are as follows:(1)Group technology is used to analyze the parts of sheet metal distribution box.The parts are described by using the orientation description method combined with the main and auxiliary features.According to the spatial orientation,the parts in the box and the features on the parts are extracted as nodes,and the membership relationship is used as the connecting line to establish the part network.Through the data analysis of a large number of distribution box parts network,it can provide some knowledge basis for the judgment and reasoning of expert system,provide the basic type of parts for the automatic modeling process,and use the group technology to classify the similar parts family to get the composite parts,and use the composite parts to analyze the design process,modeling process and process flow suitable for all parts of the parts family.(2)Use VB language to develop Solid Works.That is to say,the built-in API function of Solid Works is called to make it more suitable for the actual needs of enterprises in the sheet metal manufacturing market,so as to achieve the purpose of customized functions.Through the analysis of the general modeling process of parts by group technology,the automatic modeling in the part environment and the quick assembly function of the box body in the assembly environment are realized.That is to say,the system should be able to draw a new part model according to the user’s input information,and use the series design table of parts to realize the size driven modeling that keeps the structure of the model unchanged,avoid the repeated design of the model,reduce the workload and shorten the production cycle.(3)Using VB language and Solid Works software and MATLAB software to make the sheet metal feature extraction system,which can automatically extract the features needed by the expert system.Firstly,Solid Works software is used to traverse the features and feature sketches in the model design tree to obtain the dimension information of the part features,and then MATLAB software is used to process the exported sheet metal part development drawing to obtain the processing information of the features in the development drawing.According to the order of the outer ring,inner ring and straight line,the purpose of identifying the hole shape and straight line is achieved,and two-dimensional processing coordinates of the features are output.In order to follow up the process planning according to the information of processing characteristics and knowledge base process rules.(4)Expert knowledge is used to judge the rationality of the scheme,and to infer the part modeling process and technological process.The process knowledge is expressed as symbolic numerical conditions,and the process selection is carried out in the way of forward reasoning and judgment.Then the process of NC stamping and laser cutting is optimized with artificial intelligence algorithm.The firefly algorithm is selected to optimize the machining path.Firstly,the geometric center of the closed loop is extracted to optimize the machining path of the fixed node.Then,the firefly algorithm is used to select the initial machining points on each loop to realize the variable machining path optimization of the nodes and obtain the optimal machining path.Through practical operation,this system can realize the automatic modeling,virtual assembly and process planning of common distribution box,which is accurate and reliable,and has practical value.