Research And Application Of Automatic Feature Recognition And Process Planning For Prismatic Machining Process

The integration of CAD/CAPP/CAM is the critical technique to realize intelligentization and automatization for modern manufacturing system.The sharing and transfer efficiency of data between processes restricts the integration technique.At present,automatic feature recognition techniques may be implemented for CAD / CAPP integration.As for the integration of CAM,it mainly relies on manual operations to process the identified features,which is separate from feature recognition,leading to reduced efficiency.A scheme that integrates automatic feature recognition and process planning based on prismatic machining process is proposed in this thesis.The scheme takes the automatic feature recognition as the core,and combines the processing requirements to extracting prismatic features from the solid model.Based on the processing related information analyzed from the identified features,machining data can be obtained from process database.Then process planning can be carried on using these related information.Based on the scheme described above,the main contents of this thesis are as follows:(1)Recognition of transitions and features consisting of cylinder or cone with rule-based technique.For simple features consisting of a few faces,use rule-based technique could improve recognition efficiency.(2)Extension of model attributed adjacency graph(AAG)with the attributes of B-rep model elements.The geometry and topology properties of B-rep model face and edge elements can be obtained from solid model and assigned to model AAG.This method provides detailed predefined rules for feature recognition based on graph-subgraph matching.(3)Recognition of prismatic features based on machining reverse order using graph-subgraph matching.Recognizing machining feature in reverse order of actual feature processing.Then update model AAG based on the identified features to obtain the AAG before the stage reduction of the workpiece.This method has the advantage for identifying features in different processing stages.(4)Process planning based on machining data filtered from process database by feature information.Analyze processing related information for identified features.Then the predefined operations can be obtained by the related information.Optimize the process and complete the process planning of the identified prismatic features.