Research And Implementation On Thermal Monitoring System For Machine Tool Spindle Based On The Passive Wireless Surface Acoustic Wave Technology

With the increasing requirement for machine tools’machining precision, the research on thermal error of machine tools becomes more important. The thermal deformation on spindle which is the core function part of machine tools, will affect the entire working performance, so the research on thermal monitoring technology of machine tool spindle is of great significance. This paper, with study of the related theory of surface acoustic wave (SAW) temperature sensor technology, proposes a spindle thermal monitoring method based on passive wireless SAW sensor technology which is verified by experiments.Firstly, the background and significance of the research are presented and the research status of machine tool spindle thermal monitoring technology and passive wireless SAW sensor technology are introduced in detail. Then, the basic related theory of SAW sensor technology including the structure and classification of SAW sensor is elaborated. Considering the features of different SAW sensors and application environment of this paper, single port resonant SAW temperature sensor is chosen for temperature monitoring with the temperature measurement principle and frequency response characteristics are discussed.Secondly, after the integrated design of SAW thermal monitoring system is done, the paper expounds the design and implementation of the RF transmitting chain and RF receiving chain in detail. The RF transmitting chain includes local oscillator module, power amplifier module and RF switch module, and the RF receiving chain mainly includes down-conversion module while every module is designed, made and tested carefully to meet the requirement of transmitting and receiving chains. Besides, the upper computer software is designed and programming realized.Finally, with research of antenna design theory, in order to analyze and optimize performance of the SAW thermal monitoring system, different experiments are made to research the influence of different factors to signal transmission quality, such as signal transmission distance, angle between transmitting antenna and receiving antenna and metal surroundings. And based on the experiment results, the optimization of signal transmission quality can be made. Based on that optimization, the static thermal monitoring experiments and spindle thermal monitoring experiments are made. The static experiment proves approximate linear relationship between resonance frequency and temperature. The spindle thermal monitoring experiments is made by comparing SAW thermal monitoring system with the traditional cable thermal monitoring system. The result shows that the SAW thermal monitoring system is better than the cable thermal monitoring system, because the former can acquire temperature field data more directly and reflect the spindle temperature changes more clearly. In conclusion, the method of spindle thermal monitoring based on passive wireless SAW sensor technology is effective and superior.