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由于铸铁件毛坯表面粗糙以及游离石墨的存在,当用超声波探伤时,使超声波被大量散射,信噪比下降,且盲区大,使对铸件区表面的缺陷检测尤为困难.因此,迄今一直适用X、γ射线作为无损探伤的主要手段.近年来,作者(属日本大学工程学院)研究了一种探测铸件近表面缺陷的方法,并开发了一种名叫“多换能器”的新型探头,这是一种由三个压电晶片组合成的一个整体探头.晶片尺寸均为5×5mm,工作频率为5MHz,其显著特
Due to the rough surface of cast iron blank and the presence of free graphite, when ultrasonic flaw detection, the ultrasonic wave is scattered a large number, the signal to noise ratio is decreased, and the blind spot is large, so that it is very difficult to detect the defects on the surface of the casting area.Therefore, , Γ ray as the main means of non-destructive testing.In recent years, the author (School of Engineering, Nihon University) has studied a method of detecting near surface defects of castings and developed a new type of probe called “multi-transducer” This is an integrated probe made up of three piezo-electric chips with a chip size of 5 × 5 mm and a working frequency of 5 MHz,