Design And Realization Of Electromagnetic Ultrasonic Thickness Measurement System

With the development of industry and the continuous improvement of smelting technology,metal materials are widely used in all walks of life,This is more and more stringent requirements of the metal sheet industry,in which the exact value of metal thickness is an important indicator.In the field of non-destructive testing,the measurement method of the thickness of the metal sheet is endless,and as a new non-destructive testing technique,electromagnetic ultrasonic technology has drawn more and more attention.Compared with the traditional piezoelectric ultrasonic technology,EMAT technology has no couplant,non-contact measurement,suitable for high temperature detection,And because of its non-contact measurement advantages,electromagnetic ultrasound can detect the thickness of thinned corrosion-resistant metal plates and coated metal surfaces.In this paper,starting from the principle of electromagnetic ultrasound,the basic mechanism of electromagnetic ultrasonic excitation is expounded,the mathematical formula of transducers is pushed from electromagnetism,According to the characteristics of electromagnetic ultrasonic excitation and some of its own characteristics,design and optimization of the hardware receiver circuit and software denoising extraction algorithm.On the basis of this theory and practice,an electromagnetic ultrasonic thickness measurement system with small size,low cost and fast and accurate measurement is designed.The system includes a high-voltage module,transducer drive module,ultrasonic receiver module and CPU data processing and transmission module.Respectively,in the standard steel experimental study,Experiments show that high-voltage power supply output amplitude can be adjusted,the output voltage range of 0 to300 V and-300 V to 0,to the drive circuit to provide enough energy to maximize the transducer trigger;The triggering of the transducer adopts the way of high-voltage pulse excitation,and the MOSFET in the driving circuit adopts the transformer-coupled driving mode to realize the isolation between the front stage and the back stage.Ultrasonic receiver module to achieve the signal extraction,amplification and filtering functions;software envelope extraction of the signal,filtering and peak time difference calculation is better handled.Realized the accurate measurement of the standard thickness of the steel,the measurement accuracy of 0.5mm.