Research On Milling Temperature Testing Technique Based On Thin Film Thermocouple

The complex thermal coupling effect of cutting area produces much cutting heat,which is directly related to machining quality and tool wear.The measurement of cutting temperature is of guiding significance for the research of cutting process.For Traditional methods have many disadvantages,such as difficult to wire and long response time thermo sensitive elements,which makes it difficult to measure the temperature of milling area accurately and in real time since the spindle is rotating at high speed.Aiming at the above problem,the research on milling temperature testing technique based on thin film thermocouple is studied by depositing thin film thermocouple temperature sensor in milling tool tip and combining with wireless transmission technique,which realizes the in-situ measurement of cutting area temperature in milling process accurately and in real-time.The specific research contents are as follows:The milling process is simplified as a problem of plane strain and 3D orthogonal cutting model is built by utilizing ABAQUS finite element software to obtain the temperature distribution nephogram in cutting area and cutting edge nearby.The temperature of rake face has little difference to the rear face near the cutting edge of tool tip,which is also the maximum temperature distribution area of tool.The simulation provides reference basis for subsequent deposition position of thin film thermocouple.The thin film thermocouple temperature sensor is prepared by DC pulse magnetron sputtering.It is found that SiO2 insulation film is uniform in thickness and excellent in insulation performance with insulation resistance about 3.65×107? by fractionated deposition method,which overcomes the drawbacks of needle hole defects in traditional preparation process.The prepared NiCr/NiSi thin film thermo electrode has regular shape and neat border.The heat electrodes are tightly bonded and form temperature measuring terminals,which ensures good conduction of temperature measuring loop.Static and dynamic characteristics of prepared thin film thermocouple blade are analyzed.The Seebeck coefficient is around 41.17?V/? and dynamic response time is 83?s.Theoretical analysis shows that the dynamic response time of thin film thermocouple is related to film density,specific heat,thermal conductivity and thickness of thermo junction,and has nothing to do with the surface area of thermo junction.The wear condition of film thermocouple in cutting process is simulated through preparing different widths of thermal contacts.The technical characteristic of wear thin film thermocouple maintains stability,which means the milling temperature can be accurately measured in some degree.A wireless acquisition system for milling temperature measurement is designed through applying ZigBee wireless transmission technology and combining with self-developed PC temperature monitoring system,which realizes the milling temperature data real-time storage,processing and display.The performance of milling temperature in-situ measurement system is tested through field milling experiment and the best deposition position of thin film thermocouple on tool tip is determined.The experiments show that the measurement system can realize real-time monitoring of milling temperature region and detect the change of temperature within 200ms,which provides a new technical support for milling temperature measurement.