Investigation Of Temperature Field And Thermal Shock Features Of End Mills In High-Speed Milling

The process of high speed milling(HSM) is interrupted cutting. There exists thermal shock effect in the tool with cutting edge cutting in and out the workpiece periodically. It is very important to research on high-speed cutting temperature for the mechanism of high-speed cutting. The tool cutting temperature and the thermal shock characteristics have been the research emphasis in the field of high-speed machining.According to the complexity of milling process, the difficult of measuring milling cutter temperature and so on. In this paper, taking solid cemented carbide milling cutter as the research object, based on the extensive collection and analysis of related information of temperature field mathematical modeling in high-speed machine. The characteristics of heat conduction problem is that the heat source has a certain shape, size and heating output, while most boundary conditions are unknown during milling process. Therefore, the heat source method has advantages in heat conduction problem of milling process compared with other methods. Based on the heat source method, the dynamic temperature field mathematical modeling is established.Because of the sealing property of motorized spindle and complexity of milling process, there are not mature and accurate methods to measure the cutting temperature of high speed. In order to study the temperature change legislation in cutter cutting process and reverse the heat flux input knife internal body the temperature measuring experiment is designed. In this experimental work, the embedded temperature measuring tool holder system is employed. Finally, the measuring point temperature curve of milling 304 stainless steel plate by XH714 D machining center is obtained. There exists good agreement with the real milling temperature changes through the analysis of the cutting process temperature curve, the initial milling temperature rises rapidly and then the temperature gradually stabilized.The material of the end milling is cemented carbide, belongs to brittle material, so the thermocouple must be placed on the surface of material. Meanwhile, the flat end milling cutting process is interrupted cutting, therefore the cutting temperature is a fast unsteady process. Although the temperature can be measured, the surface heat flux cannot be derived directly by simple calculation the internal temperature gradient of the flat end mill. The heat distribution cannot be calculated accurately. However, the heat flux of flat end milling rake face can be obtained by solving inverse heat conduction problem through surface temperature. In this paper, the series expression of heat source is obtained with particle swarm optimization algorithm, based on the forward problem solving of the dynamic temperature field mathematical modeling of end milling.Using ANSYS transient thermal analysis module, the reversed heat flux is loaded, according to different time periods, to tool chip contact area of end milling rake face. Then, write a DO loop through APDL of ANSYS secondary development module load implements the Leads imitate the real cutting process of the cycle. At last, the characteristic of the end mills transient temperature field distribution and temperature gradients are derived.The change of surface morphology and microstructure in end milling cutting zone are observed by Hitachi S-4800 scanning electron microscope(SEM) after milling process completed. Based on the ANSYS analysis of transient temperature field, re-entering the pre-treatment of the thermal unit to the corresponding structural units. Then the temperature analytical results is applied to the structural analysis model as a load. As a result, the distribution of thermal stress is obtained. The comparison results show a good agreement between the SEM pictures and simulation results.