The Machinability Research Of LD Cold Work Die Steel

LD steel is a typical cold working die steel.The quenched LD steel has the advantages of high toughness,high wear resistance and so on.It can meet the needs of various cold working dies.It has significant influence on tool life,production efficiency,workpiece surface quality and machining cost.The cutting performance of LD cold working die steel is studied,and suitable tool materials and tool geometry parameters are selected.It is of great significance to optimize the milling process conditions and summarize the changing rules of cutting force,temperature and chip of LD cold working die steel,which is of great significance to promote the processing and wide use of LD cold working die steel.In this paper,numerical simulation,experimental research and theoretical analysis are used to analyze the influence of cutting force and cutting temperature on the cutting force and cutting temperature,the size and distribution of cutting force and cutting temperature,the shape of chip,tool wear and surface quality of workpiece under dry cutting conditions.In the numerical simulation,the material constitutive model is established,the process parameters are defined,the orthogonal experimental scheme is designed,and the range and variance analysis of the cutting force and cutting temperature distribution in the simulation are carried out.The effects of cutting parameters on the change of forces and temperatures in each direction and the optimal process scheme are obtained.The results show that the cutting depth AP has the greatest influence on each cutting force,followed by the feed rate FZ per tooth.Finally,the feed speed v,and with the increase of cutting parameters,the three forces appear obvious increase phenomenon.The chip surface temperature is generally higher than the blade tip and the surface temperature of the workpiece.The cutting speed and the feed quantity of each tooth mainly influence the degree and length of the spiral winding of the chip,and the cutting depth mainly affects the size of the chip.In the experimental research,orthogonal design test and single factor test were used to analyze the influence of cutting parameters on cutting force,workpiece surface roughness,chip shape and tool life.The results show that the change of cutting depth AP has the most significant effect on the change of triaxial cutting force.The change of feed per tooth fz has the greatest influence on the surface roughness value Ra of the machined workpiece.With the increase of feed rate per tooth the value of Ra increases gradually and the surface quality becomes worse.With the increase of cutting speed,the surface quality of the chip decreases and the surface quality becomes better.The cutting speed v and the feed rate f?z per tooth affect the shape of C or spiral shape of chip,the degree of curl and the length of chip.For the optimization of cutting parameters oriented to the size of total force F,in order to make the total cutting force minimum,vibration minimum,energy consumption less,the optimal cutting process parameter is:v=50m/min,f_z=0.030mm/z,a_p=0.5mm.The cutting parameters oriented to the machined surface roughness are optimized.In order to make the surface quality better,the optimal cutting parameters are as follows:v=70m/min,f_z=0.025mm/z,a_p=0.5mm.through mathematical analysis,the mathematical model between cutting force and cutting parameters,between surface roughness and cutting parameters is established.The empirical formulas of cutting force and roughness are obtained,and the tool life is about 65 minutes under the optimized process parameters.