Research On Open And Intelligent CNC System Based On STEP-NC And PMAC

To date,most CNC systems use the ISO 6983 programming standard,also called G/M code.Because the standard only contains tool path information,conventional CNC systems are poor in the adaptivity,intelligence and interoperability,which seriously hinder the development of open and intelligent CNC system.To overcome the drawbacks of ISO 6983,a novel programming standard called STEP-NC(STEP-compliant Numerical Control,STEP-NC)has been developed by International Organization for Standardization.Based on object-oriented concepts,it utilizes machining features to describe the machining tasks and uses workingsteps to describe the machining process,which provides a good condition in the function level for the realization of the open and intelligent CNC system.In addition,the PMAC card is amulti-axis motion controller with good openness and stability,which provides a good support in the hardware for the realization of the open and intelligent CNC system in the hardware level.Therefore,the thesis works on the research about the open and intelligent CNC system based on STEP-NC and PMAC after comprehensivly analyzing the research about STEP-NC-compliant CNC system and its relevant technologies at home and abroad.The main research contents are described as follows:(1)The background of the research is firstly introducted.Then,the research about STEP-NC-compliant CNC system,STEP-NC-compliant program interpreter,STEP-NC-compliant process planning and STEP-NC-compliant tool path planning at home and abroad are elaborated and the existing shortcomings are summarized.Based on it,the research contents of this thesis are given.(2)Aiming at the exsiting problems of current STEP-NC-compliant CNC system,the architecture of a novel open and intelligent CNC system based on STEP-NC and PMAC is established,which includes software architecture and hardware architecture.On this basis,the cross-platform STEP-NC-compliant program interpreter is established,which mainly includes the lexical analysis module based on finite stste machine,the information extraction module based on DOM4J,the information display module based on tree structure and JAVA3D and the information storage module based on MYSQL.(3)Aiming at the existing problems of present STEP-NC-compliant process planning,an oriented-workshop intelligent process planning method is proposed.Firstly,according to the proposed matching rules of machining resources,the corresponding machine tools and cutting tools are chosed for each machining workingstep.Then,taking the auxiliary machining time as the optimization objective,the improved chaotic Hopfield neural network algorithm is used to optimize the STEP-NC machining workingstep sequence.Finally,combined with Pareto theory and congestion theory,the improved multi-objective chaotic Hopfield neural network algorithm is applied to the multi-objective optimization of STEP-NC machining parameters,which realizes the adaptive and intelligent process planning.(4)Aiming at the existing problems of STEP-NC-compliant tool path planning,the shortest tool path for multi-island complex cavity based on STEP-NC is studied.Firstly,a Voronoi diagram algorithm for multi-island complex cavities is proposed.Based on it,the Voronoi diagram for multi-island complex cavities is generated,and its tool cutting paths are generated according to the cutting distance.Then,the tool transition paths are generated by PH splines curve and oblique double arcs.Finally,the improved chaotic Hopfield neural network algorithm is used to optimize the tool path,which results in the generation of the shortest tool path for multi-island complex cavity based on STEP-NC.(5)Taking Visual C#as the development environment and using the WinForm application development framework,an open and intelligent CNC prototype system based on STEP-NC and PMAC was developed on the platform of Win 10 system.And,its functions are demonstrated by a case.