| As a new type of machining method,plung milling has been widely used in aerospace,hydropower and other industries because of its characteristics of large metal margin removal,stable processing process and not easy to vibrate.Cr13 stainless steel is generally used in the part of the water bucket of hydraulic turbine,and the energy consumed in the process is mostly converted into heat energy.The long term unreasonable use will cause the cutter to break down and affect the precision of the machine to be processed.Therefore,it is very important to understand the cutting performance of the cutter.However,the research on the cutting performance of the plunge milling tool is still relatively few.In this paper,the following research is mainly done on the plunge milling tool with different rake angles:Firstly,the temperature field of cutting area in plunge milling machining is analyzed.According to the characteristics of plunge milling machining,the cutting temperature field model is established,according to the characteristic that cutting temperature accumulates up Z,Based on the superposition of heat sources,a heat transfer model of finite instantaneous heat source is established.Based on the inverse method,the required heat source intensity is solved,and the temperature changes of cutting tools in two different states are analyzed.The empirical formula is established according to the characteristics of discontinuous machining,and the instantaneous cutting force modeling is completed.Based on the finite element analysis method,the strength theory analysis is completed,which lays a theoretical foundation for the subsequent simulation analysis.Finally,the thermodynamic coupling equation in the cutting process is established.Secondly,the workpiece of this paper is a hydraulic turbine bucket,and its material is Cr13 stainless steel.According to the characteristics of the material,such as high thermal strength and easy bond breakage with the cutter,the suitable blade and blade body material are selected.The structural design based on UG,including cutter type,geometric dimension,is used to design four kinds of plunge and milling cutters with a front angle of(+1°,-1°),(+3°,-3°),(+5°,-5°),(+7°,-7°)respectively.Thirdly,by using DEFORM to simulate the machining process of plunge milling,the relationship among cutting force,cutting temperature and cutting tool strength of four kinds of plunge with the rake angles are analyzed under the same cutting conditions,and the influence of the rake angle of the cutting tools on the cutting force,strength and temperature is analyzed.The influence of the cutting tool rake angle on the tool deformation and the distribution of the temperature field are obtained through the analysis of statics,thermal stress and tool deformation by ANSYS.Based on this angle,the influence of spindle speed,feed rate per tooth and radial cutting width on cutting temperature and cutting force is analyzed.Finally,the influence of spindle speed,feed rate per tooth and radial cutting width on the cutting force is analyzed by using the orthogonal test method and the experimental data measured by the dynamometer.The results are compared with the results of DEFORM simulation analysis.The prediction model of cutting force of plunge milling is established by means of range analysis of test results.The optimal cutting parameters are selected according to the maximum removal rate and the minimum deformation of the tool,and the wear experiments are carried out to observe the tool wear. |
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