Resrarch And Development Of Feature-based On-machine Measurement System For Nc Machining Center

There are lots of parts(contain hole and surface)with high accuracy requirements need to be manufactured in many application areas such as aerospace and automobile industry.Those parts desire for high surface profile accuracy.However,influenced by the flexibility of part,unwanted dimensional errors cannot be avoided,the part requires being moved to a Coordinate Measurement Machine to check its dimensional accuracy.It will cause re-setup error if the part need to rework.On-machine measurement can be adopted to avoid above problems,to ensure the quality of processing,has important research significance and engineering application value.Based on science and technology major project “High-grade CNC Machine Tools and Basic Manufacturing Equipment”,this paper carries out research on key technologies of model-based machining center OMM system.First,the details of overall technical scheme,measurement principle and procedure,software and hardware composition and integration method of probe and machining center have been described and analyzed.The factors affecting measurement accuracy and compensation method are analyzed.Then,model-based OMM planning has been researched.Based on the proposed method of judging the direction of normal vector of a certain point on the surface,the internal and external properties of cylindrical,conical and spherical surface are judged.Finally,with an example of a feature block,the feature extraction module and measuring program auto-generation module are introduced.The OMM system platform has been built based on above research and the software system has been developed based on Open CASCADE geometric kernel.The block and ring gauge are inspected and the maximum error is under 10?m.Besides,through the experiment of coordinate system set-up and the feature block inspection,shows that the OMM system can improve the accuracy and efficiency of manufacturing.