基于超声波的铸铁烘缸测厚研究

Study on Ultrasonic Thickness Measurement of The Cast Iorn Dryer

造纸用铸铁烘缸作为一种压力容器,在使用过程中应进行超声测厚,但由于铸铁材料的特殊性,普通测厚仪无法准确测量铸铁厚度。利用带A扫信号的超声波检测仪,在铸铁阶梯试块上进行比对实验,得知在一定的压力和温度范围内,铸铁声速、硬度和金相基本保持不变,因此可以利用烘缸凸缘部位校准声速。通过对不同超声波探头的比对实验,得知不同频率、不同晶体尺寸探头的优缺点,对提高铸铁烘缸测厚的精确度有较大帮助。

Cast iron dryers are used as a kind of pressure vessels,and the thickness should be measured in?ultrasonic tests.However,materials of cast iron are special,so ordinary thickness tester cannot accurately measure the thickness of cast iron.From the comparison experiments on Cast iron staircase test block?by ultrasonic detector with A scanning signal,it is known that the Ultrasonic sound velocity,hardness and metallographic structure of cast iron remain unchanged in a certain range of pressure and temperature.Accordingly,we can calibrate the Ultrasonic sound velocity of cast irons by edge of parts,and get the advantages and disadvantages of the Ultrasonic probes with different frequencies and chip sizes through comparison experiments of different ultrasonic probes.It is helpful to improve the accuracy of measuring thickness of cast iron dryers.