Error Evaluation And Compensation Of Complex Surface Parts Through On-line Inspection

In digital manufacturing era, higher speed, higher precision and higher efficiency put forward a higher demand to Numerical control machining, meanwhile, the inspecting technique of workpiece get a rapid development on basis of CAD module, high-precision inspection technique and error evaluation of workpiece faced a great challenge. Coordinate measuring machine (CMM) have been used in advanced manufacturing environments to make sure that the manufactured parts have a high dimensional accuracy, However, some problems still exist such as the errors caused by the second fixing operation and incapable of large part measurement measure large parts. Therefore, for the problem that it is difficult to measure and evaluate the machine error of complex surface part. This paper focus on the research on on-line inspection system development based on standard CAD model of STL format, the main work will be concentrate on error compensation of measure data, surface reconstruction, surface error, machine error compensation, then it contains the following respects:(1) For the on-line inspection technology on machine error of complex curved surface part. It will do some survey research include measure mode, surface reconstruction, and pre-travel error compensation. On the basis of analyses on present research situation of home and abroad, we will confirm the key technique in the respective area.(2) On basis of fully understanding online inspection technique, in this thesis, A great deal of analysis have been concentrated on pre-travel error compensation which based on BP neural network, and probe radius error compensation which based on three-dimensional compensation method, all of this depended on a detailed analysis and research on error source of online inspection system. (3) After measure the finished workpiece, surface reconstruction based on bicubic non-uniform B-splines will be used to express the shape of complex surface parts digitally.(3)On the basis of surface reconstruction, It will propose a method how to get the surface error on the use of Differential Evolution algorithm, from which compare the position deviation between reconstructed surface and CAD module. Meanwhile, A method will be proposed to realize the machine error compensation from modify the original NC machining code has been proposed.(5) Based on the VisualC++6.0 and OpenGL 3D graphics interface, an online inspection and error evaluation system of machining tools for free-form surfaces parts has been developed and put in practice. An experiment to testify the precision, reliable and trustworthy was implemented.