Development Of Cutting Temperature Monitoring System And Research On High Temperature Mechanical Properties Of Cutting Tool Material

Cutting temperature is an important physical quantity in the research of cutting process,and the actual cutting area of the tool is very small,so it is difficult to measure the cutting temperature accurately and real-time.Therefore,it is necessary to develop a real-time on-line monitoring system for cutting temperature.During the cutting process,under the action of intense force-thermal load,especially the cutting thermal load,the microstructure of the tool material evolves,and the macroscopic mechanical properties of the tool material are closely related to the material microstructure,and the mechanical properties change accordingly.Therefore,it is of great theoretical significance and engineering application value to establish the organic correlation between cutting temperature,microstructure and mechanical properties.In this paper,a real-time on-line monitoring system of cutting temperature was developed.Taking YT5 cemented carbide tool material as the research object,the influence of cutting heat on the mechanical properties of the tool was studied from the microscopic scale,and the cross-scale analysis method was used to predict the key mechanical properties of the tool material at high temperature.A tool cutting temperature monitoring system is developed by using thin film thermocouple technology.The temperature field distribution of the tool was verified by three-dimensional finite element simulation and the deposition position of the thin film thermocouple on the tool front was determined.The Ni Cr-Ni Si thin film thermocouple temperature measuring tool was prepared by femtosecond laser,electrolyte-plasma polishing,plasma-enhanced chemical vapor deposition and magnetron sputtering.Combined with high-precision signal acquisition card,a tool cutting temperature monitoring system platform was built to provide technical support for real-time online monitoring of cutting temperature.The sensitivity and accuracy of the cutting temperature monitoring system were verified and applied.The sensitivity threshold of Ni Cr-Ni Si film thermocouple is obtained by analyzing the relationship between diffused thermoelectric potential rate and film thickness.The static characteristics of thin film thermocouple were studied by static calibration experiment.The temperature measuring accuracy of the film thermocouple was verified by the temperature measuring tool system.The stability and reliability of the film thermocouple in the cutting process were verified by the cutting test,and the temperature field distribution and evolution of the front tool surface were studied by the finite element simulation,which provided the basis for the loading of the boundary conditions in the subsequent research.The microstructure model of cemented carbide tool material was constructed by Voronoi algorithm,and the high temperature mechanical properties of the tool material at the microscopic scale were studied by using the model.Scanning electron microscope was used to characterize the morphology of carbide tool materials.Based on the real microstructure characteristics of materials,the microstructure model of cemented carbide was established by Voronoi algorithm.The stress state,microstructure evolution and high temperature mechanical properties of the tool materials under thermal loading were studied by inserting cohesive units into grain boundaries and grains.By using the homogenization model and the extended finite element method,the cross-scale analysis is carried out to predict the bending strength of carbide tool materials at high temperature.The mechanical properties of different microstructure models were homogenized,and the finite element simulation model of three point bending macro homogenization was established.The crack propagation behavior during bending was studied,and the macro bending strength of carbide tool materials at different temperatures was calculated.By comparing the simulation results with the bending test results,the effective prediction of bending strength of cemented carbide tool materials at different temperatures was realized.