Wear Simulation Of Cold Extrusion Punch And Research Of Coating Strengthening

In this paper,the forming process of cold extrusion piece was simulated by a finite element simulation software.The response surface was utilized to study the influence of the fillet radius and forming speed on surface temperature and wear depth of the top die.Based on the numerical simulation results,a multi-objective genetic algorithm was used to optimize the fillet radius and forming speed,so as to simultaneously reduce the maximum temperature and maximum wear depth of top die.Subsequently,Ti N,Ti Al N and Ti Al Cr N coatings were designed on the surface of top die,so as to strengthen the mold surface and further improve the die life.The wear behaviors of W6Mo5Cr4V2 substrate and three kinds of coatings were researched by experiments.The results show that the coating materials can greatly enhance the surface hardness,wear resistance and service life of top die.Specific research contents were as follows:1)In the finite element simulation software Deform,the extrusion process was simulated,and the surface temperature distributions and wear behaviors of top die were detailedly analyzed.The influence of fillet radius,forming speed,and friction factor on the maximum surface temperature and maximum wear depth was studied.2)The fillet radius and forming velocity were set as independent variables,and the maximum surface temperature and maximum wear depth were set as target response variables to establish response surfaces,so as to explore the influence law among them.Through the analysis of variance,the regression relationships between the target response variables and independent variables are highly significant.In order to simultaneously reduce the maximum temperature and maximum wear depth of top die,based on the numerical simulation results,a multi-objective genetic algorithm was used to optimize the fillet radius and forming speed.The results show that the optimization effect of multi-objective genetic algorithm is significant.3)TiN,TiAlN,and Ti AlCrN coatings were successfully coated on W6Mo5Cr4V2 substrate by the arc ion plating technique.Vickers hardness values of W6Mo5Cr4V2,Ti N,Ti Al N,and Ti Al Cr N were measured by microhardness tester.The binding forces between coatings(Ti N,Ti Al N,Ti Al Cr N)and W6Mo5Cr4V2 matrix were qualitatively and quantitatively determined by Rockwell hardness tester and scratch tester,respectively.Subsequently,the wear tests of several materials were conducted by the HT-2001 POD pin disk wear tester.The surface profiles of W6Mo5Cr4V2 matrix and coatings were measured by Dektak 150 profilometer.Their wear coefficients were calculated,so as to evaluate wear resistance.4)After optimizing the fillet radius and the forming speed,the service life of W6Mo5Cr4V2 die is 1.06 times as long as the original die.After optimizing the fillet radius and forming speed and coating Ti Al N material,the service life of top die is 3.8 times as long as the original die.