发动机旧连杆缺陷超声检测研究

Ultrasonic Testing of Flaws in Discarded Connecting Rod of Engine

连杆是传递发动机曲轴和活塞动力的重要零部件之一。对旧连杆进行再制造可以降低生产成本,提高企业竞争力。根据超声检测方法的优点,针对连杆材料及易损伤部位制作了相应的超声波探头,并采用小波分析方法对检测结果进行降噪处理。结果表明:连杆大头与杆身过渡处是易损伤部位,通过横波斜探头可实现该区域缺陷的检测;以sym4小波为母小波,对检测信号进行降噪处理,可在一定程度上抑制"噪声",从而提高试验结果精度;建立降噪前后回波幅值与声程的关系式,并采用指数函数对其进行拟合可初步实现缺陷定量的无损评价;根据试验验证结果可知,采用该方法对旧连杆能否进行再制造进行评价是可行的。

Connecting rod, usually used to transfer power, is a vital part of engine, so remanufacturing of discarded connecting rod can reduce production cost and improve company competitive power. In this paper, based on the merits of ultrasonic wave testing, by designing and preparing probe of shear wave, the region that is usually damaged firstly is tested, and the testing signals are treated and analyzed by the method of wavelet. The results show that the transition region from connecting rod big end to rod body, which was tested by probe of shear wave, was damaged firstly. When sym4 wavelet was regarded as mother wavelet, the noise signal could be suppressed by method of wavelet analysis, and the shape of ultrasonic wave became smoother than the shape of original wave. By calculating the fitting curve of data between sound path and amplitude of echo wave, the flaws and the size of flaws in discarded connecting rod were tested and evaluated. From the results, this method can be used to evaluate whether the discarded connecting rod can be remanufactured.