Study On Performance Of High Speed Dry Cutting P20 For Cemented Carbide Coated Tools

P20 steel belongs to pre-hardened plastic mold steel,which is widely used in the manufacture of various precision molds.However,the hardness of the material reaches 30-36HRC,and the hard alloy cutting tool is used for high-speed cutting and processing,which has problems such as large cutting force,high cutting temperature and serious tool wear.At present,the research on coated carbide tools for machining P20 die steels is mostly high-speed milling,while the research on high-speed turning machining is rarely reported.The research of coated carbide tools for turning P20 die steel and optimization of cutting parameters is of great significance for ensuring the quality of mold processing,reducing production costs,and increasing productivity.This paper investigates the differences in the processing of P20 die steels using different coated carbide tools in high-speed dry turning.In this paper,the performance of CVD hard alloy coated tools,PVD coated hard alloy tools and self-made Ni-CVD coated hard alloy tools were studied in high-speed machining of P20 die steel.CVD carbide coated tools and PVD coated carbide tools are purchased tools,and Ni-CVD coated carbide tools are self-made tools.The Ni-CVD coating applies a method of electroless Ni plating to the cemented carbide substrate.In order to increase the autocatalytic performance of the plating solution,I g/L of copper sulfate(CuSO4 · 5H2O)is added to the electroless Ni plating formulation.The cemented carbide is plated in an ultrasonic bath at 60-70°C environment for plating about 2 hours.A 2-3 ?m thick nickel-copper-phosphorus ternary alloy coating will be deposited on the surface of the cemented carbide,and then under the temperature of 1000°C coating CVD about 15?m thickness.In this paper,based on the orthogonal test,high-speed machining of P20 die steel is performed using CVD hard alloy coated tools,PVD coated carbide tools,and self-made Ni-CVD coated carbide tools.Axio CSM 700 confocal microscope was used to observe the machined surface and measure the roughness of the machined surface.The influence of the three cutting factors on the machining surface quality of P20 die steel was studied,and the cutting parameters were optimized.Scanning Electronic Microscope(SEM)and EDS spectrometers were used to observe and analyze the front and back surfaces of the tools respectively.The wear of different coated cemented carbide tools was studied,and the wear mechanism of coated cemented carbide tools was explored.The results show that three different coated carbide tools for dry cutting of P20 die steel,the cutting depth has the greatest effect on the surface roughness,followed by the cutting speed,and the influence of the feed rate is the smallest.At the same time,it was found that for different carbide coated tools,the optimal cutting process parameters are different.CVD coated hard alloy tools are suitable for roughing under cutting parameters of Vc= 150(m/min),f=0.2(mm/r),ap=0.4(mm),and PVD coated carbide tools are suitable for finishing under cutting parameters of Vc =400(m/min),f=0.05(mm/r),ap=0.1(mm),while Ni-CVD coated carbide tools are suitable for finishing under parameters of Vc=150(m/min),f = 0.05(mm/r),ap = 0.1(mm).At the same time,the study also found that when using Ni-CVD coated carbide cutting tools for rough cutting of P20 die steel,the tool wear is very serious,mainly manifested as diffusion wear.At last,based on the Deform-3D simulation software,the cutting of P20 die steels with cemented carbide tools were simulated.The influence of cutting parameters on the cutting force was studied,and the distribution of cutting temperature during the cutting process was analyzed,and the tool wear mechanism was further analyzed.The analysis results obtained are in good agreement with the experimental results.