Study On Three-dimensional Morphology And Corrosion Resistance Of Milling Surface Of Hardened Steel Die

Milling production of hardened steel plastic molds has huge market demand.Compared with traditional grinding processing,hard milling processing has higher processing flexibility and processing efficiency,can reduce pollution,save energy and obtain better processing surface quality.Hard milling has become one of the key technologies for the research and development of China's mold manufacturing industry.In order to improve production efficiency,try to avoid manual polishing and subsequent surface treatment.The hard milling surface as the final use surface has become the goal and trend of mold processing.However,the plastics processed in the mold are easily heated to decompose hydrogen chloride and hydrogen fluoride which are corrosive gases,and these gases can cause corrosion on the cavity surface of the plastic mold,leading to failure,which is difficult to control.At present,the problem of corrosion prevention and control is seldom solved from the aspect of hard cutting technology.The surface morphology produced by different milling processes is different,so that the parts have different corrosion resistance.Through a series of milling experiments and corrosion tests,the relationship between machining parameters,the three-dimensional morphology of the machining surface and the corrosion resistance of the machining surface is studied in this paper.The specific research contents are as follows:Based on the metal cutting theory,a theoretical model of the residual height of the milling surface of a ball-end milling cutter is established according to the characteristics of ball-end milling.It is concluded that simply reducing the machining distance and feed amount,or increasing the radius of the ball-end milling cutter will reduce the residual height of the machining surface,which can better provide theoretical guidance for cutting experiments.Taking Cr12MoV hardened steel as the research object firstly,the magnitude of the correlation between the three-dimensional morphological parameters and the corrosion resistance of the workpiece was obtained through the periodic corrosion test combined with the gray correlation analysis method.Then the influence of machining parameters on the three-dimensional topography of the machined surface was studied by single-factor milling experiments.The test results show that when the cutting speed is equal to 197m/min,the machined surface is relatively flat,the arithmetic mean deviation of the surface contour is the smallest,the surface support index is the largest,and the machined surface has good wear resistance.When the feed rate is small,the skewness of the processed surface is negative and the surface support index is large.When the cutting depth is equal to 0.2mm,the machining surface is relatively flat,and the arithmetic mean deviation of surface contour is the smallest.When the row spacing is equal to 0.1mm,the contour amplitude of the processed surface is evenly distributed,the arithmetic mean deviation of the surface contour is the smallest,and the surface support index is the largest.The smaller the tool radius,the fewer burrs and peaks on the machined surface,the smoother the machined surface,and the greater the surface support rate.Based on the orthogonal experiment,the variance analysis and multivariate nonlinear regression modeling of the 3d morphology parameters of the processed surface were conducted,and the significance of the influence of the processing parameters on the 3d morphology parameters was obtained.It can be seen from the coefficient table of the multi-component nonlinear regression model that the interaction of factors has a significant influence on the three-dimensional topography.BP neural network is used to model and predict the three-dimensional topography of the processed surface,and the prediction accuracy meets the requirements.The acid corrosion environment was simulated.Through electrochemical corrosion experiments,the machining surface of the workpiece had the best corrosion resistance when the cutting speed was equal to 197m/min,the feed rate was equal to 0.15mm/r,the cutting depth was equal to 0.2mm,the row spacing was equal to 0.1mm,and the tool radius was equal to 5mm.When the skewness is close to 0,the smaller the kurtosis value,the more corrosion resistant it is.