Study On Damage Behavior Of Carbide Tools In Heavy Cutting Process

Heavy cutting is an important part of extreme manufacturing,nuclear power water chamber head is the main parts,material is the 508? steel,as difficult-to-cut materials with high strength,hardness and plasticity,the cutting tool is subjected to a large cycle impact load in the process of machining,which leads to the serious problem of the tool damage failure.At the same time,the heavy cutting process has the characteristics of large cutting parameters and unequal machining allowance.The cutting force and the cutting heat change violently,and the tool damage is accelerated.Cemented carbide is the main material for cutting tools,the initial damage in the process of preparation and the damage defect in the process will be continuously germination and accumulation under the action of heavy cutting machine-thermal load,with the increase of cutting time,the micro defect in the tool material evolves gradually to form the macroscopic damage crack.,the crack continues to expand,and the tool damage fracture occurs eventually.Aiming at the above problems,the damage behavior of cemented carbide tools in heavy cutting process is studied.First of all,the machining characteristics of heavy cutting process are analyzed mainly from the structure,material and machining technology of water chamber head;Combined with milling experiment and simulation,the cutting force and cutting heat are studied,and the influence of load characteristics on the damage during heavy cutting process is discussed;It provides a theoretical basis for the study of the damage behavior of cemented carbide tools.Secondly,the research process and basic theory of damage mechanics are discussed;The milling experiment of water chamber head is carried out to determine the main failure modes of cemented carbide tool;Based on the damage theory and the properties of cemented carbide materials,the micro and micro damage analysis of cutting tools is carried out,and the formation and evolution process of tool damage are defined;Combined with the finite element simulation,the model of tool damage failure is predicted and analyzed,and then the mechanism of tool damage is revealed,which provides a basis for the study of the damage model of cemented carbide tools.Thirdly,the damage constitutive model and the basic theorem of damage variables are summarized;The microstructure of cemented carbide is analyzed,and the constitutive relation of material is studied;The damage model of cemented carbide tool is established;The experiment of cemented carbide Hopkinson pressure bar is carried out to study the dynamic characteristics of materials;The damage characteristics of the materials are discussed by the tensile test of the cemented carbide at high temperature;The macroscopic influence of the temperature on the materials is analyzed from the micro perspective,and the damage variables are characterized by different parameters.It is of great significance to improve the research on the failure mechanism of the tools.Finally,the main factors affecting the damage behavior of cemented carbide tools are analyzed;In order to reduce the damage,the cutting tool parameters are optimized to improve the tool life and production efficiency,and provides technical support for heavy and efficient cutting.