Simulation And Experimental Study On Surface Topography Of Multi-media WEDM

Due to the continuous development of high-speed WEDM technology in recent years,when WEDM is processed in gas for multiple times,although the workpiece surface quality is continuously improved due to the increase of cutting times,certain straightness errors tend to appear when the workpiece reaches a certain thickness,that is,the size is large in the middle and small at both ends,which greatly affects the surface topography of the workpiece.It is found that excessive vibration of electrode wire will not only affect the surface quality of workpiece but also affect the straightness error.So the research on surface morphology of workpiece in atmospheric medium has become the focus in recent years.In this paper,the mechanism of WEDM discharge was studied,the fluid field model was established,the boundary conditions of fluid simulation were determined,and the fluid field simulation was carried out on the workpiece with thickness of20 mm,40mm,60 mm and 80 mm respectively in different media.The pressure and velocity cloud map under different injection speeds and pressures were obtained,and the optimal injection pressure parameters were optimized.The influence on the vibration of electrode wire is analyzed.The vibration model of the electrode wire was established,and the modal analysis was carried out to analyze the natural frequency and amplitude of the electrode wire under different tensioning forces and regulating wheel span.The amplitude simulation of the electrode wire was carried out to analyze the amplitude of the workpiece with different thickness in the atmospheric medium,and the transverse amplitude during finishing was obtained.Combined with the actual processing situation and the research content of the fluid field,the fluid-structure coupling simulation of the electrode wire was carried out,so as to study the influence of the flow field force on the amplitude of the electrode wire,and optimize the basic parameters of the experimental design of the machine tool.Finally,the deflection of electrode wire with different electrical parameters was simulated,the influence of workpiece thickness variation on straightness error was analyzed,and the influence law of straightness error was obtained.According to the actual processing situation,the single factor temperature field simulation analysis was carried out for the 80 mm thickness workpiece,and the temperature field simulation was carried out for the workpiece with different thickness according to the experimental parameters.According to the simulation results,the size parameters of the pitting are obtained,and the volume of a single pitting is calculated.According to the actual distribution of discharge points,the workpiece with different thickness is divided into corresponding regions,and the uniformity of discharge points within the region is assumed,and the erosion volume is calculated by region.Orthogonal experiment was designed for workpiece with different thickness and range analysis was carried out to find the influence law of different electrical parameters on the evaluation parameters of workpiece surface topography.The straightness obtained in water-based working fluid is compared with that in atmospheric medium.The measured surface roughness,straightness and erosion volume are used to verify the accuracy of the above simulation results.