Surface Morphology Simulation And Roughness Prediction Of Parts Facing 5-axis Side Milling

With the rapid development of the aerospace industry,people have put forward higher requirements for the streamlined shape of aviation products.Five-axis linkage CNC machine tools are widely used in the processing of aerospace products because of their excellent linkage performance.At the same time,in order to improve the processing efficiency,the features of the ruled surface on the part are mostly completed with fiveaxis synchronous side milling.In the case of five-axis simultaneous side milling,a lot of research has been done on the distribution of part surface error,but few works related to the surface topography of parts have been involved.The surface micro-topography is used as the evaluation basis for the surface quality of the workpiece,which has an important influence on the service life of the components.For this reason,we studied the surface topography simulation method of the parts in the five-axis side milling and the influence of milling vibration on the surface roughness of the parts.First,we establish a simulation model of workpiece surface topography for five-axis side milling.Through the obtained part machining code and the established geometric model of the tool with milling edge,we can calculate the spatial coordinates of any point on the milling edge at any time.Then by calculating the relative position between the tooth point and the surface point of the discrete workpiece,it is judged whether to keep the corresponding tooth point as the residual trajectory of the tooth on the workpiece surface.During the entire computational simulation process,the discrete points on the workpiece surface need to be updated as the tool teeth cut out of the workpiece surface.In order to explore the influence of milling force on the surface topography of the workpiece,we established a five-axis milling force model based on discrete surfaces.The contact area between the tool and the workpiece is calculated by performing Boolean operations on the discrete workpiece surface and the mathematical model of the tool.The tool is discretized into a series of micro-elements and a corresponding tool micro-element coordinate system is established at each micro-element.A corresponding milling force model is established at each micro-element,and the corresponding cut-in and cut-out angles can be calculated through the micro-element coordinate system and the contact area within the micro-element.By vector-synthesizing the calculated milling forces for each microelement,the total milling force at the current location can be obtained.The last part is part surface dynamic topography simulation modeling.The hammering test was performed at the tool tip to obtain the frequency response function of the machine tool system,and then the modal parameters of each mode shape were calculated by the modal analysis method.According to the obtained modal parameters,the corresponding dynamic differential equations are established,and the simulink simulation model corresponding to the differential equations is established.By simulating the milling force obtained by the simulation to the simulink model,the vibration displacement curve of the tool can be obtained.The theoretical tool trajectory is updated according to the tool's vibration displacement,and it is brought into the topography simulation model to finally obtain the dynamic simulation topography of the workpiece surface.Through the final experiment,we verified the accuracy of the topography prediction model.By adjusting the speeds of different spindles,we have found that the tool tooth passing frequency and its multiple distance from the system's natural frequency month circle,the smaller the tool vibration,and the smaller the workpiece surface roughness.