The Research Of Methods For Crankshaft Using Ultrasonic Phased Array Technology

As the core components of engine, crankshaft bears extremely complex dynamic loads during the running of engine. Fatigue cracks are produced easily inside crankshaft. So, in order to ensure the safe operation of the engine, it is necessary to detect the R-area of crankshaft.Conventional ultrasonic testing is the main way to detect R-area of crankshaft at present. But defects are easily missed by conventional ultrasonic testing because of using general probes and moving probe frequently. The full range of crankshaft can be detected completely by the function of electronic scanning, deflection and focusing of acoustic beam of ultrasonic phased array technology. The software is used to distinguished defects quickly based on VB. The main work of this paper as follows:Firstly, spatial mathematical model of crankshaft, sectional model of crankshaft, beam coverage model of cross-sectional are established by analyzing the geometric structure of crankshaft, and simulation of the real sectional figure and section of beam coverage.Secondly, each model of crankshaft is programed by Visual Basic. Section of crankshaft can be draw quickly, the status of acoustic beam coverage can be displayed vividly, defects and these locations can be identified quickly by this software.Finally, the most proper detection parameters of ultrasonic phased array are choosed based on the simulation. The ultrasonic phased array calibration block of crankshaft and a set of sample with artificial defects are designed and manufactured. Ultrasonic phased array inspection process of crankshaft is designed by this software. Detection experiments of blocks are completed by ultrasonic phased array technology and conventional ultrasonic technology. The defect location accuracy is analyzed, and the effects of two methods of detection are analyzed and compared.The research result shows that the real shape of acoustic beam cross-sectional of crankshaft can be simulated by the section model based on drawing to a certain extent. In detection process, parameters setting of ultrasonic phased array can be guided by the software which is programmed by VB, meanwhile cross-section can be drew rapidly, the echo signal can be recognized and defects can be located by this software too. The detection results of artificial blocks shows that defects can be missed by conventional ultrasonic testing technology. The notches whose width are between 0.2mm and 0.5mm, depth are between 5mm and 14 mm in the region of crankshaft R-area can be detected effectively by ultrasonic phased array. Meanwhile the echo of crankshaft itself can be identified accurately. The location error of software is validated less than 2mm by experiment of Φ2mm artificial hole. Ultrasonic phased array technology can detect defects of crankshaft effectively and overcome the disadvantages of missing defects in detection process and overcome low sensitivity with conventional ultrasonic technology, and improving the working efficiency.