Principle And Development Of Thin Film Thermocouple Sensor For Measuring Dynamic Cutting Temperature Of Chemical Explosive Material

The dissertation is supported by China Academy of Engineering physical important fund subject (No. 2001Z0301). The present work dedicates to the research on the dynamical cutting temperature and cutting force measuring system when machining chemical explosive material. The newly developed NiCr/HSS semi-artificial thermocouple and NiCr/NiSi thin film thermocouple measuring systems are submitted to use on the spot.Hard particles distribute randamly inside chemical explosive materials. Large quantities of heat generates and instantaneous high workpiece temperature pulse will occur when cutting one of these particles. There will be much danger when the workpiece temperature exeeds a special value. An effective method for measuring such instananeous workpiece temperature in war industry enterprise is badly needed in order to improve the productivity and assure the safety of processing.The tool/chip thermocouple is a widely used technique for measuring cutting temperature. But the tool and chip cannot form into a natural thermocouple when machining non-metal materials such as chemical explosive material. The implanted thermocouple cannot measure the workpiece temperature directly because the thermocouple junction is away from the workpiece. Infrared radiation pyrometer can response fast. Unfortunately, such systems are costly and the machining has to be performed dry. In allusion to the features of cutting chemical explosive material, new type of fast response temperature sensors-NiCr/HSS semi-artificail thermocouple and NiCr/NiSi thin film thermocouple are developed, which integrate both cutting and temperature measuring functions. The main works dedicate to:(1) Structure design, machining and fixing of NiCr/HSS (W18Cr4V high speed steel) semi-artificial thermocouple temperature measuring cutter. Static calibration of the semi-artificial thermocouple is carried out within the temperature range: 0 ℃~600℃. The sensitivity of the thermocouple is not less than 12.9 μ V/℃. The non-linearity error is less than 0.3%. The response time of the thermocouple is calibrated and calculated as 12.5 ms.(2) The LC-EX-03 I type of reference temperature compensation and output signal amplifier for the semi-artificial thermocouple is developed. The dynamical cutting temeprature and cutting force measuring system for chemical explosive material machining is contrived. The response time of the whole measuring system after adopting the phase-leading circuit is decreased to 1.94 ms. The relative temperature error of the measuring system is less than 2.13%. The repetition error of the system is within 1%.(3) SiO2 insulating film is deposited on HSS substrate for the first time by means of Microwave Electron Cyclotron Resonance (MW-ECR) plasma enhanced Radio Frequency (RF) reaction non-balance magnetron sputtering technique. The SiO2 film has good insulating performance, density, uniform and proper stoichiometry. The optimal parameters for preparing SiO2 film are found.(4) The AFM and SEM images of surface topograph for SiO2 film are detected. Theelement percentage of the film are analysed by XPS and FT-IR. The DC insulation resistence, adhesion force, friction and thickness of the SiO2 film are measured.(5) The measuring principle of the thin-film thermocouple and the size effect of thin-film are expatiated. Structure design, manufacturing and fixing of the NiCr/NiSi thin film thermocouple temperature measuring cutter are completed. NiCr/NiSi thin films are plated on the insulated HSS cutter. Static calibration of the thin film thermocouple is carried out. The sensitivity of the thermocouple is 20.9 μV/℃. The non-linearity error is less than 0.32%.(6) The theoretic thermal conduction model of the thin film thermocouple is deduced. And the response time of the thin film thermocouple is carried out.(7) Newly developed LC-EX-03II type of reference temperature compensation and output signal amplifier for the thin film thermocouple has better noise filter performance. Dynamic calibration of the NiCr/NiSi...