The Thickness Measurement System Of Cylindrical Objects Based On Ultrasonic

The wall thickness measurement of cylindrical objects is still based on manual mechanical contact method in the industry. But on one hand, it has different degrees of damage to the measured surface. On the other hand, it can not measure the wall thickness of some hermetic and irregular objects. In this paper, a high-precision thickness measurement technology and system design methodology based on ultrasonic are supposed.The paper analyzed the basic theory of ultrasonic wave, wavelet denoising method and power spectrum estimation method. To measure the wall thickness of cylindrical objects, it designed a high-precision and real-time ultrasonic thickness measurement system which consisted of ultrasonic defect detector, mechatronics control system , data acquisition system and data processing unit .First, it advanced the device selection and optimization principle for the cylindrical objects thickness measurement system and determined specific devices to meet the system requirements. It analyzed and compared several commonly ultrasonic thickness measurement methods. According to the particular of the system, this paper used pulse echo method. It designed mechanical and electrical rotary stepper control system which based on the layout method of conventional probe; used fluid coupling method and designed special shaped probe coupled device; designed high-speed data acquisition system in accordance with the collection targets; designed the data processing unit based on the noisy and cyclical characteristics of the echo signal.Then, it analysed the advantages and disadvantages of wavelet threshold denoising method and advanced an improved threshold algorithm for the ultrasonic echo signal denoising; analysed the power spectrum estimation method and deduced the wall thickness formula based on power spectrum estimation. It could bring about wall thickness measurement of cylindrical object. Finally, the papar accomplished the installing of hardware and software . Through the analysis of experimental data ,we found that the improved threshold algorithm has higher SNR than the traditional method in denoising process. Burg maximum entropy method could control the thickness errors in 0.8%. It proved that the system has high precision and reliability .