| The manufacturing industry is the key of a country,the cornerstone of a country’s economic development and the basis of enhancing national competitiveness.Displacement sensor is an essential part of closed-loop detection or accurate control,and plays a pivotal role in the field of processing and manufacturing.However,in metallurgy,mining,power generation equipment and other large or heavy machinery industries,there are extreme conditions such as large and heavy loads,or special occasions such as narrow,hollow and weight limits.The traditional displacement sensor is difficult or even impossible to install,but these industries have this demand,the embedded time-grating(ETG)displacement sensor for its opened up a new way.The ETG displacement sensor is a new type of displacement sensor that can realize embedded measurement based on time grid displacement sensor.It can take the given transmission parts(such as gear and rack)as a part of the sensor without changing the original transmission characteristics of the mechanical system,targeted design of the corresponding sensor probe,so as to construct the ideal traveling wave signal,which puts forward high requirements on the design of sensor probe.However,the theory of ETG displacement sensor is rough and imperfect.Based on it,this paper carries out the research work of ETG displacement sensor for gear parts,including the following aspects: 1)The magnetic circuit analysis model of ETG displacement sensor for gear parts based on magnetic equivalent circuit method is established.Taking sinusoidal and cosine core as specific examples,the variation laws of air-gap reluctance/permeance under various conditions are discussed in detail.Finally,the traveling wave equation is established;2)Taking the spur gear with modulus 3.5 and number of teeth 84 as the specific object,the rationality and correctness of the previous theoretical results are verified from the perspectives of theoretical calculation and finite element simulation;3)The prototype was developed and the experimental platform was built.The basic signal,resolution and accuracy of the ETG displacement sensor with sinusoidal and cosine cores were tested.The experimental results show that the resolution of the two sensors is 0.46 " and 3.78",the measurement errors in the entire range are 0.056° and 0.015°,and the linearity is 0.016% and 0.004%,respectively.The main measurement error components of the sensors were analyzed,which are mainly caused by the original error,eccentric installation and induced residual signal.Three important conclusions are obtained from the above research and analysis: 1)There is a correlation between the core width and the fourth harmonic of the sensor measurement error.Selecting an appropriate value can greatly suppress or even eliminate the higher harmonic and improve the quality of traveling wave;2)For the sinusoidal core,if the pitch is constant,half of the pitch is the optimal for the designed core width,regardless of the tooth thickness and space at the tip line/circle.For the cosine core,the maximum value of the tooth thickness and space at the tip line/circle is the optimal for the core width;3)The structure of the ETG displacement sensor optimized in this paper still inevitably has a certain original error,which is embodied in the first harmonic with a small amplitude,but can be suppressed by shortening the length of the core.To sum up,the magnetic circuit analysis model of ETG displacement sensor for gear parts proposed in this paper can effectively guide the design and optimization of core,and also improve and refine the relevant theories of ETG displacement sensor.Compared with the previous ETG displacement sensor,the sensor in this paper has higher resolution,higher original accuracy,and more compact structure,which can be applied to the large or heavy machinery industries in the presence of large,heavy and other extreme conditions or narrow,hollow,weight limit and other special occasions. |
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