Study On The Temperature Field Modeling And The Real-time Online Temperature Measuring Technique For The High Speed End Mill

During the cutting process of machining operation, cutting heat and the cutting temperature caused by the cutting heat not only directly affect the wear and the life of the cutter, but affect the machining and surface quality of the workpiece as well. As for the cutting temperature, it is crucial in online measurement, which is of great significance in studying the wear and life decrease of the cutter caused by the cutting heat. For the cutter that is in the middle of the cutting process, the cutter temperature online measuring technique can monitor the changes of the cutting temperature, which is able to supply a powerful guarantee to the machining security and offer the technical support for the machining quality. Therefore, it is essential to study on an approach which can measure the temperature of a single point continuously without changing the structure of the principle axis and simultaneously obtain the temperature data. For analyzing the wear of the cutter caused by the cutting heat, monitoring the changes of the cutting temperature during the cutting process and ensuring the machining security and quality, this study is of great significance.For the high-speed cutting process, we apply the thermocouple in measuring the temperature. We use fusion welding to fix the thermocouple junction on the highest temperature point of the flank surface of the end mill and put the tail of the thermocouple into the lower computer of the modified hilt. Then, with the wireless transmission, we transmit the temperature data to the upper computer to process and finally achieve the continuous online temperature measurement of a specific point on the cutter during the high-speed cutting process. Furthermore, based on the general planning, we propose the explicit performance requirements through system analysis and carry out a deep theoretical and experimental research.Focused on the features of the high speed end mill, we build the mathematical model for the temperature field using the heat source method, and with the help of the finite elements software, we simulate the temperature field and temperature distribution. Based on the mathematical model and the simulation results, we analyze the temperature rise of the cutter caused by the cutting heat and further determine the position with the highest temperature, which offers the theoretical basis for the determination of the temperature measuring spot, the optimization design of the end mill and the design of the cutting experiment, etc.For the reliable thermocouple temperature measurement, in addition, we study on the installation of the thermocouple and the measured cutter, achieving the reliable online continuous temperature sensing of a certain point in the temperature field without ruin the original intensity and temperature field of the cutter. Besides, we study on the tails of the thermocouple and the installation of the lower computer. We put the tails of the thermocouple into the hilt and modify the structure of the hilt to offer the installation space for the lower computer, which still meets the original technical standard. To realize high speed sampling, we utilize two micro A/D converters while outputting the thermal electromotive force and use time-interleaved parallel sampling method to increase the sampling rate by 2 times. Moreover, we study on the reliable high speed wireless data transmission approaches. With the UDP protocol, we introduce the check bit and the check matrix. The lower computer groups, packs and transmits the temperature data and the upper computer corrects, combines and processes the received data. The improved UDP protocol is able to eliminate data disorder as well as the package error and achieve the high speed reliable wireless data transmission.For the temperature measuring system which is consisted of RC network, A/D conversion and the cold junction compensation, we build a mathematical model for it and get its static and dynamic analysis. Meanwhile, we implement the characteristic simulation and offer time constant of the system as well as the highest frequency when the amplitude loss is 0.1%. According to the built model and referred to the transmission path of the temperature signals, we carry out the uncertainty analysis, which is aimed at verifying the measuring range and accuracy of the system.For the developed high speed end mill specific point continuous online temperature measurement system, we carry out the wireless data transmission experiment. We verify that after the process of the improved UDP protocol, the data received by the upper computer has no error or disorder, which proves its reliability. Besides, we use the precise temperature verification furnace to achieve the calibration of the measuring system, and then give the static measurement error of the temperature measuring system. At last, we apply the developed temperature measuring system in the real-time online continuous measurement experiment to verify the developed system.