Development Of Universal Post-processing System For Five-axis NC Machine Tools

After calculating full information of tool path has been acquired by the general CAD/CAM software. However, in order to meet the requirement of CNC machine tools,post-processing is needed to acquire NC code applied to CNC machine tools.Based on the relevant information of NC machine tools and CNC systems,universal post-processing system translates cutter-location files into NC machining programmes that NC machine tool can be identified.It is one of the key CNC programming technologies as well as an important component of NC system.Principle of universal post-processing system is presented,and on the basis of the principle,the structure of the system is designed.The three key contents for the system is researched as following.(1) The kinematics modeling for 5-axis CNC machine toolsThe motion structure of current popular 5-axis CNC machine tools is researched.According to the configuration of the two axes,motion forms of 5-axis CNC machine tools are summed up with 12 motion forms classfied into three types.Based on the characteristics of the 12 motion forms, kinematics models for the 12 kinds of CNC machine tools are built.And with the models,cutter-axis vectors and cutter-tip coordinates from CL files can be converted into motion component on the axes of NC machine tools.(2) The compensation for nonlinear machining errorThe formation mechanism of nonlinear machining error is analysed, and the distribution of nonlinear machining error is presented.The expressions for the error are derived,and the compensation for the over-error part is carried out with fractionizing cutter location(CL) points.(3) The compiler design for the post-processing systemThe compiling principle of the post-processing system is described,and the differences and relations between the code format of CL files adopted by general CAD/CAM systems and the format regulated by ISO is researched.The structure of the popular CL files is analyzed, and the universal CL rule is regulated. After summarizing the characteristics of NC codes in a variety of control systems,NC code rule is regulated.Based on the rules of CL code and NC code, the realization flow of the compiler of the universal post-processing system is schemed out.With the above-mentioned,universal post-processing system for five-axis NC machine tools is developed in Visual C++6.0.