Research On Cutting Service Of TiB₂-ZrC Cermet Tool Toughened By Nano-Carbide

The application of advanced engineering materials and the development of high-speed mechining technology have placed higher requirements on the performance of tool materials.TiB₂ ceramics are regarded as one of the most promising cutting tool materials for their excellent physical and chemical properties and mechanical properties.However,the low fracture toughness of TiB₂ ceramic has severely limited its development and application.Therefore,this paper combined the toughening needs of TiB₂-ZrC cermet tool materials with the performance requirements of advanced cutting tools to design and optimize TiB₂-ZrC cermet tool materials with excellent microstructure and mechanical properties,verify the cutting performance of the tool when continuously cutting Ti6Al4V,monitor and recognize the wear status of novel tools during cutting service by deep learning theory,finally,realize the design concept of“design–preparation–cutting–monitoring”.Firstly,TiB₂-ZrC cermet tool materials containing different nano-carbides were fabricated by vacuum hot-pressing at different sintering temperatures.The effects of nano-carbides and sintering temperature on phase composition,microstructure and mechanical properties were evaluated,and the relationship between mechanical properties and microstructures was discussed.The toughening mechanism of sintering temperature and nano-carbide additives on TiB₂-ZrC cermet tool materials were revealed.The black core-gray rim structure solid solution generated in TiB₂-based cermet tool materials contributed to the improvement of toughness.The nano-carbides additives can significantly decrease the grain size of TiB₂.The incorporation of vanadium carbide(VC)and niobium carbide(NbC)significantly improved the flexure strength and hardness of the composites,while the introduction of VC and tantalum carbide(TaC)significantly improved the fracture toughness of the composites.The grain size,relative density and mechanical properties of the composites were optimal at a sintering temperature of 1650°C.In this study,the typical core-rim structure,the good solubility of VC,the pinning effect of Ta C,and the deflection and branching of cracks jointly improved the mechanical properties of TiB₂-ZrC cermet tool materials.Secondly,taking cutting force and workpiece surface roughness as optimization targets,the cutting performance of TBV1650 tool for continuous cutting of titanium alloy Ti6Al4V was studied based on response surface method(RSM)and the Box-Behnken design(BBD).It was found that the feed rate and cutting depth significantly affected the surface roughness and cutting force,respectively.The optimal cutting parameters were v_c=120m/min,a_p=0.16mm,and f=0.1mm/rev for cutting force as the optimization target.The cutting length and cutting time can reach 1326m and 13.3 min,respectively.In the verification experiment,the forecasting errors of cutting component forces F_a,F_r,and F_v were 5.64%,18.11%,and 9.14%,respectively.The optimal cutting parameters of were v_c=100m/min,a_p=0.15mm,and f=0.1mm/rev for surface roughness as the optimization target,and the cutting length and cutting time can reach 3233m and 29.4min,respectively.The forecasting error of surface roughness in verification experiment is 3.19%.Due to the excellent fracture toughness and surface hardness of TBV1650,the main wear mechanisms were adhesive wear and diffusion wear.Lastly,aiming at the problems of high cost and low efficiency of traditional tool wear status determination methods during the serviceof tools,this paper proposed a method for online monitoring of tool wear status based on deep learning theory,which combines adaptive feature extraction and wear status classification,and used the time domain signal of cutting forces directly judges the tool wear status.The study showed that the accuracy of tool wear condition monitoring based on convolutional neural network can reach more than 94%.