Research Of Key Technologies On Generating And Extracting Inspection Information Of Complex Parts Based On3D CAD

With the development of CAD (Computer Aided Design) technology, it has developedgradually from2D to3D environment for extracting parts’ coordinate measuringinspection information. However, inspection information is usually got by neutral filessuch as IGES (Initial Graphics Exchange Specification), STEP (Standard for the Exchangeof Product Model Data) or by feature recognition and tolerance matching based on3Dannotation parts model. Common problems such as different ways of inspection, data lossduring transmission and complexity of extracting information are existed in the correlativeway of extracting inspection information. Model based on MBD (Model Based Definition)provides a thorough representation of inspection information in3D environment, whichmakes extraction of inspection information more intuitive and convenient.The research of key technologies on generating and extracting inspection informationof complex parts based on3D CAD is supported by the National Natural ScienceFoundation of China titled as "Research of key technologies on generating and extractingdetection information of complex parts and intelligent three coordinates measuring", GrantNo.51075119.The main research work includes the following aspects:(1) MBD model of parts is defined clearly as the object for extracting inspectioninformation aiming at the problems existed in traditional CAD model of parts whenextracting inspection information from it. At the same time, the inspection information isanalyzed, according to the modeling specifications of MBD parts model and measurementrequirements.(2) Associative geometric information is defined based on tolerance annotationsaccording to the dominant and recessive expressions of the related information of MBDdataset. The representation model of parts inspection information is established based onMBD dataset by way of taking tolerance items, relevant geometric features and modeldatum/coordinate system as constitutive elements of inspection information and definingrelationships between them.(3) The process of parts’ inspection information identifying and extracting isdetermined according to measuring information composition and representation model.(4) The inspection information of the parts is extracted in the platform of Visual C++2008aiming at MBD datasets of the parts built in Pro/E environment by usingPro/TOOLKIT development tool. (5) The inspection information is stored into the corresponding database, which is thedata foundation of the Coordinate Measuring Machine.During the study of extracting technology of parts’ inspection information, identifyingand extracting parts inspection information required by CMM measurement in full3Denvironment has been realized in the paper by using MBD model of parts as the object ofextracting inspection information.