Study On Cutting Force And Surface Topography In Milling Of Hardened Steel Mold Considering Machining Inclination Angle

Automotive panel mold has a large size,complex surface,surface quality requirements of higher characteristics.With the development of hard cutting technology,in order to ensure the processing efficiency,milling technology is widely used in the field of mold manufacturing.Milling force is one of the most important physical parameters in milling.Milling force not only affects the cutting heat,but also causes deformation of the tool and vibration of the processing system to affect the quality of the surface processing.The changeable directions and cutting forces is easy to result in decreased stability,machined surface quality and accuracy,and the reduction of cutter life in ball-end milling of hardened steel molds with free form surface by three-axis NC machine tool.Therefore,it is of great practical significance to study the cutting force,tool deformation and surface topography of free-form surface hardened steel ball milling process for improve the manufacturing technology of automobile panel mold and the development of the processing technology of the free form surface.When the ball-end mill milling free-form surface,the tool inclination and the curvature of the workpiece cause the actual contact position of the cutting edge and the contact area of the cutter constantly changing.The micro milling force analysis method is used to establish the milling force model of the ball-end mill.Based on the experiment of variable feed slot cutting,linear regression analysis method is used to fit the regression equation of average milling force and feed per tooth,and obtain the cutting force coefficient.Aiming at the problem that the machining inclination angle and the curvature of the workpiece cause the change of direction and size of the milling force,the curvature characteristics of the freeform surface and the machining inclination are characterized.The instantaneous cutting force model considering the machining lead angle,slip angle and uncut chip thickness is established.The model is modified to study the effect of workpiece curvature and machining inclination angle on theinstantaneous milling force.Matlab software is used to simulate the threedimensional milling force of free form surface,and the experimental verification is carried out to provide the basis for tool deformation analysis.The effect of tool deformation on the actual three-dimensional trochoidal trajectory of cutter is analyzed by finite element method.The deformation of ball-end cutter caused by free-form surface instantaneous milling force is studied.The uncut chip thickness considering the amount of tool deformation and the initial angle of tool deformation is established.The free-form surface milling force prediction model model is validated experimentally to provide a theoretical basis for the prediction of surface topography.Based on the actual three-dimensional trochoidal trajectory movement of tool teeth,the prediction model of surface topography considering tool deformation and machining inclination angle is established.The influences of tool inclination on three-dimensional arithmetic average deviation of surface topography,and on scallop height are analyzed.it provides a theoretical guide for processing technology.