Design Of Cermet Tool Material Based On Wear Prediction And Its Cutting Performance

In order to meet the machining requirements of difficult-to-machine materials in various fields of production and life,the tool should have the ability to cut difficult-to-machine materials at high speed.Cermet cutting tools have the advantages of high hardness and high temperature resistance of traditional ceramic cutting tools and good strength of cemented carbide cutting tools,it can maintain good cutting ability when cutting difficult-to-machine materials at high speed,it will become the key cutting tool materials in the future.However,the research and development of cutting tool materials still adopts the experimental method,which has disadvantages such as high cost,time-consuming and labor-intensive.In addition,tool wear is the most intuitive criterion for evaluating tool cutting performance in the test.Therefore,this topic combines simulation technology and tool wear theory to predict tool wear,reveals the influence of tool material components and its volume fractions on wear.Thus guide the design of cermet tool materials,reduce tool development time and cost,improve tool development efficiency.The thermal-mechanical coupling relationship between tool and chip during high-speed cutting were studied.The deformation and failure characteristics of 06Cr19Ni10 stainless steel during high-speed cutting were analyzed.A reasonable constitutive model,damage model,failure criterion and friction model were selected.The Ti(C₇,N₃)/Ti B₂/WC cermet tool as the research object was taked,the heat transfer and force relationship between the tool-chip contact surface were analyzed.The calculation method of the average temperature of the rake face of the tool was used.A method for solving the friction heat distribution coefficient of the tool-chip contact surface in cutting simulation was proposed.The above-mentioned influencing factors of thermal-mechanical interaction in cutting process was considered,a thermal-mechanical coupling model of 06Cr19Ni10 stainless steel cutting process was established.A prediction method for cermet tool wear at the micro-scale was proposed.A tool material microstructure model considering components and its volume fractions was established,material properties was set by using of subprograms;combined the cermet tool microstructure model and the thermal-mechanical coupling model of the cutting process,the cutting process of different components of tools was simulated by finite element simulation;the tool wear subroutine was compiled according to the tool wear model.The tool temperature,contact stress and slip velocity obtained in the cutting simulation were input into the tool wear subroutine.The wear rate of each node of the tool model was obtained.Tool wear profile generated by nodal displacement method;Compared the changes of the tool wear morphology of different components,it was found that the wear change of Ti(C₇,N₃)/Ti B₂/WC tool was the smallest,when the proportion of Ti B₂ was 20%and the proportion of WC was 15%.The influence of the tool material composition and its volume fraction on the changes of peak temperature,cutting force and contact stress during the cutting process was analyzed,the influence rule of the tool material composition and its volume fraction on the evolution of tool wear was revealed.The optimal composition of the tool material based on the wear prediction results was determined.The Ti(C₇,N₃)/Ti B₂/WC tool material was prepared by plasma sintering process,and the sintering process parameters of the tool material were optimized.The optimal sintering temperature and holding time were 1550?and 30 min,respectively.The mechanical properties of the developed tool material were tested,its bending strength was 1096.45 Mpa,the hardness was 18.9 Gpa,and the fracture toughness was 9.85 Mpa·m^1/2.Through the cutting experiment of 06Cr19Ni10 stainless steel,the cutting performance of the prepared tool was studied and compared with the commercial cermet tools SNMN120708.The results show,the optimal cutting speed of the two tools was 150 m/min,when the cutting speed was 100 m/min and 150 m/min,the cutting distance of the prepared tool was greater than that of SNMN120708;when the cutting speed was 200 m/min and 250 m/min,the cutting distance of the SNMN120708 tool was larger.The main wear mechanism of Ti(C₇,N₃)/Ti B₂/WC and SNMN120708 tools was adhesive wear,and no trace of abrasive wear was found.