| As a typical difficult to machine material,titanium alloy has the characteristics of poor processing performance,difficult cutting,easy to cause tool wear,high cutting temperature and so on.The traditional drilling method is difficult to meet the process requirements.Helical milling technology has certain advantages in difficult to machine materials.At present,special milling cutter is widely used in helical milling,which has the problems of difficult manufacturing and high cost.Ball end milling cutter can not only meet the conditions of axial feed,but also its "S" shaped cutting edge is conducive to heat dissipation and chip removal,which is more suitable for helical milling.In this paper,the application of ball end milling cutter in helical milling technology is systematically studied,which provides a reference for further optimization of helical milling technology.Firstly,based on the kinematics of helical milling,the kinematics geometric model of ball end milling cutter is established.Through discrete cutting edge micro elements and coordinate system,the coordinate matrix transformation is carried out,and the tool path equation of helical milling of ball end milling cutter and the instantaneous undeformed chip thickness of workpiece are calculated.In this paper,the cutting geometry is used to analyze the helical milling process of opposite milling cutter and ball end milling cutter,and then the micro element calculation of cutting edge is analyzed to compare the changes of axial force,radial force and cutting force in the process of helical milling.Based on the micro element cutting principle,this paper analyzes the removal of workpiece materials at different characteristic times in the process of helical milling with ball end milling cutter,quantitatively calculates the volume of materials to be cut,and establishes the kinematics simulation model for the process of helical milling with ball end milling cutter by using UG software.The validity of the theoretical analysis is verified by the kinematics simulation of the cutter.Secondly,the 3D finite element simulation model of helical milling with ball end milling cutter is established in ABAQUS software,and the finite element simulation of helical milling process of titanium alloy is carried out to obtain the workpiece morphology of helical milling process with ball end milling cutter.The experimental platform for helical milling of titanium alloy with ball end milling cutter was built to carry out the cutting experiment.The influence of cutting force on the quality of hole making and the influence of cutting parameters on the cutting force were discussed by analyzing the experimental results.Finally,based on the theory of grey relational system,a parameter optimization method considering machining efficiency and machining quality is proposed.By quantifying the influence of cutting parameters on the optimization objective,the weight distribution coefficient is calculated by grey relational degree,and the optimization objective is solved.Through the orthogonal experimental data of titanium alloy helical milling,the proposed optimization method is verified.Compared with the empirical parameter weight distribution method,this method has better effect. |
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