Finite Element Analysis Of Milling Performance Of Die Steel Cr12MoV Based On Equivalent Tool Parameters

As it is well known,milling finite element simulation method can effectively predict the milling force,milling chip morphology,instantaneous temperature distribution,residual stress and other important physical quantities in milling process,and can provide reference for the selection of suitable milling machining parameters.Two dimensional numerical simulation method is widely used in the research of milling mechanism because of its simple structure and high efficiency.Two dimensional simulation model is transformed from the actual 3D milling model based on the conversion rule,so there are some errors in the two-dimensional milling simulation in comparison with the actual milling process.In order to improve the accuracy of two-dimensional simulation results,and make it more reliable and close to the actual,based on the previous research results,the improvement of the two-dimensional milling model is made by taking the real chip shape and the equivalent tool parameters into consideration in this thesis.And the improved model is applied to the forecast analysis of the change rule of Cr12MoV milling performance.The main work is as follows:Helical milling belongs to oblique cutting.According to the differences of tool action parameters between the oblique cutting process and orthogonal cutting process,the function expressions of the equivalent tool parameters of the cutting tool in oblique cutting,such as the equivalent rake angle,the equivalent clearance angle and the equivalent cutting edge radius of the tool,are deduced.The improved two-dimensional milling model is established based on the equivalent parameters of the tool and the true undeformed chip morphology under the true trochoid trajectory of the tool tip.In addition,ignoring the influence of helix angle,the original two-dimensional milling simulation model is constructed based on the actual tool action parameters under the orthogonal cutting,and the original model has been widely used in the two-dimensional milling simulation.Experimental verification of milling force and chip morphology show that the improved model can properly improve the accuracy of the simulation results of the two dimensional milling.Based on the improved model,the improved simulation model is established which is more suitable for the actual milling condition at the joint of hardness.The variation rules of milling force,the degree of chip curling,the serrated shape of the chip and the temperature of the cutting tool during the milling process of the joint are predicted.And the milling force,tool temperature,surface roughness under different milling methods are compared,it can provide guidance for the milling method during actual milling process of joint.The prediction model of milling residual stress is established,and the effects of different processes,cutting speed,feed rate and workpiece hardness on the residual stress are analyzed.And the residual stress distribution of the workpiece at different thickness of chip is discussed.The residual stresses at the joint of hardness under different milling methods are compared,it is found that cutting method with cutting from low hardness is not only beneficial to the uniform distribution of the residual stress on the surface of the workpiece,but also can reduce the stress concentration.