Research On Influencing Factors Of Surface Quality In Multi-axis Machining Of Free-form Surface Based On Trajectory Characteristics

Improving the processing quality of parts and improving the performance of products is the direction of manufacturing technology development.As a typical material reduction manufacturing technology,NC milling has made great progress in improving the surface quality of parts.Whether it is to study the milling cutter or to analyze the influence of processing parameters on the surface quality,it can improve the surface quality of parts in CNC milling to a certain extent.However,these are all based on the study of surface quality at the actual processing level,and little attention has been paid to the effect of trajectory characteristics on surface quality.In this paper,the influence of trajectory characteristics on the surface quality of multi-axis milling is studied.The effects of cutter location transverse distribution,trajectory transverse density and tool axis direction continuity on surface roughness of parts are studied in this paper by milling experiments.On this basis,an orthogonal experiment was designed,which included four factors: radial cutting depth,feed engagement,drift rate of cutter location and transverse density of trajectory.The influence of each factor on roughness was compared and then as a reference for improving the quality of NC milling.The effects of trajectory characteristics on surface quality are studied as follows:1)In order to study the effect of tool location transverse distribution on surface roughness,a parameter describing tool location transverse distribution,transverse migration rate,is defined in this paper.Then,in NX software,different driving surfaces are created according to the different transverse drift ratio,so that the processing trajectory meets the experimental requirements.A single factor experiment is carried out to study the effect of tool location transverse distribution on roughness under the same conditions.2)To study the influence of trajectory lateral density on surface roughness,a parameter describing the density of adjacent trajectories is defined.Then,in NX,the programming of the tool paths are completed by constructing the driving line and projecting the driving line to the machining surface.A single factor experiment is carried out to study the effect of transverse density of trajectory on roughness under the same conditions.3)As for the influence of tool axis direction continuity on surface quality of parts,this paper studies the effect of tool axis direction discontinuity on surface quality by changing the tool axis tilt angle.There are two kinds of experiments.The first is to study the effect of discontinuity of tool axis direction on the surface quality of parts.The second is to study the effect of singularity on the surface quality of parts.4)In order to compare the influence of trajectory characteristics and actual processing parameters on surface roughness,orthogonal test of four factors and three levels is carried out.These factors are radial cutting depth,feed engagement,drift rate of cutter location and transverse density of trajectory.Through the range analysis of the experimental data,the influence of different factors on the roughness can be obtained,which can provide reference for improving the surface quality.