| Thread connection,as a common connection mode,has good connection and disassembly characteristics,which makes it widely used in mechanical equipment.With the development of electronic technology and computer control technology,thread milling has been rapidly popularized.Thread milling force is directly related to the thread processing quality,tool life and processing efficiency.At present,there are some deficiencies on the prediction model of thread milling force: First,the prediction model of thread milling force based on simplified chip thickness does not consider the influence of instantaneous chip thickness,and the prediction error is large.;Second,the instantaneous chip thickness model established at present is complex,which is difficult to solve,and is not convenient for engineering application.Therefore,how to establish a more accurate and easy-to-solve instantaneous chip thickness model to improve the thread milling force model and its calculation efficiency and prediction accuracy is the key problem to be solved urgently in order to realize the application of thread milling force model in engineering.So,in view of the cylindrical thread milling process,this paper uses metal cutting theory,UG modeling software,MATLAB numerical simulation software,AdvantEdge finite element cutting simulation software,multi-axis CNC machining center and so on.By analyzing the principle of thread milling and simplifying the process of thread milling,the equation of cutting edge generating surface and the calculation model of instantaneous chip thickness are established.According to this chip thickness model,the simplified mathematical model of cylindrical thread milling force is obtained.The specific research work is as follows:(1)The establishment of the equation of cutting edge generating surface and instantaneous cutting thickness model.According to the characteristics of thread milling,the thread milling process is simplified to the side milling process.Combining with the process of tool rotation and compound motion of superimposed tool feed,the equation of cutting edge generating surface in the process of simplified milling is established,and according to the generating surface equation,the calculation model of the instantaneous cutting thickness is established.(2)Establishment of simplified prediction model for thread milling force.The cutting edges of each cutter tooth are discretized into several micro-element cutting edges,and the cutting process of each micro-element cutting edge is equivalent to the oblique cutting process.Based on the instantaneous rigid mechanics model of orthogonal cutting and oblique cutting theory,the cutting force of micro-element cutting edge is calculated by combining with the cutting thickness model established by(1).Then the cutting force of micro-element is integrated axially,and the simplified mathematical model of milling force of single-layer cutter teeth is obtained.Finally,according to the time-domain relationship of cutting process between adjacent cutter teeth,the simplified prediction model for thread milling force of multi-layer cutter teeth is obtained by superposition calculation.(3)The optimization of Tool and cutting parameters based on thread milling simulation.According to the parameters of threaded milling cutter,an accurate UG solid model of the milling cutter is established,and the influence of the AdvantEdge mesh parameters of workpiece and cutter on the simulation results of threaded milling is explored.The appropriate mesh parameters are selected by comparing the simulation results.Then carrying out 3 factor 3 horizontal orthogonal cutting simulation experiment and single factor simulation experiment to optimize the thread milling tool and cutting parameters.(4)Verification of simplified prediction model of cylindrical thread milling force.The correctness of the mathematical model of cylindrical thread milling force is verified by the simulation experiment of AdvantEdge thread milling force and the comparative experiment of cylindrical thread milling force.In summary,the simplified prediction model of the thread milling force established in this paper is simple,the prediction accuracy is high,and the calculation is stable and reliable.It will lay an important theoretical foundation for exploring the influence of cutting parameters and tool parameters on the performance of cylindrical thread milling. |
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