Improvement of ultrasonic inspection of wheelset axles of railway rolling stock

The article set the task of improving the ultrasonic inspection of wheelset axles of railway rolling stock by increasing the reliability of the inspection results. Taken into account the specificity of the wheelset axles production defects, which may occur in it due to failures in technological processes of production, located mainly near the center of the axis and extend along the axis. Such defects are gained more complete identification as a result of the ultrasonic inspection with pulse-echo method on cylindrical side with direct converter in radial direction. During ultrasonic inspection of axles on the cylindrical side in the radial direction sensitivity setting and evaluation of the permissibility of defects is performed on standardized samples of the enterprise with standard reflectors located at different depths in the inspection range. Cylindrical flat bottom 5 mm diameter reflectors are used as reference reflector, to adjust the estimated level of sensitivity, and 3 mm for adjusting the reference sensitivity level. The main disadvantage of the use of standard samples of the enterprise is the possible non-conformity of standard reflectors with technical requirements, such as the lack of parallelism of tangent plane of the flat bottom of the reflector to the entry point of the ultrasonic wave; lack of flatness of the bottom of the reference reflector; increased roughness of the flat bottom of the reference reflector, and others. The mismatch data results in decrease of the amplitude of echoes from the reference reflector, which leads to inaccurate assessment of defects in the inspected axis. To eliminate the disadvantages of standard enterprise samples more reasonable is to make a transition to the assessment of defects by the use of charts amplitude-distance-diameter, built on the use of analytical dependencies describing the amplitude of the ultrasonic echo signal from different reflective surfaces. However, the application of the graphs method amplitude-distance-diameter leads to an increased amount of noises during the process of ultrasonic inspection at the beginning of the inspected range of flaw-detection. The paper presents a mathematical apparatus and on its basis a standardless method for the setting of time function is developed to adjust the sensitivity of the ultrasonic flaw detector during the inspection of wheelset axes of railway rolling stock, allowing to exclude disadvantages of application of standard samples of the enterprise during the control and the diagram method the amplitude-distance-diameter, and accordingly, increase the reliability of the results of ultrasonic testing. To automate the calculation when setting up the time function to adjust the sensitivity of the ultrasonic flaw detector the software “NDTRT-18” was designed (Unit 5). A method for time setting to adjust the sensitivity of the ultrasonic flaw detector with developed standardless method and software product “NDTRT-18” was described. Results of the practical setting the time function to adjust the sensitivity of the ultrasonic flaw detector UD 2 - 70 with using developed standardless method for ultrasonic isnspection of the locomotive wheel seat axis of 235 mm diameter were presented. Developed standardless method and software were implemented in the public joint stock company “Luganskteplovoz” into the process of inspection of wheelset axles of diesel locomotives 2TE116U, 3TE116U, 2TE116UD with ultrasonic pulse-echo method.

railway rolling stock, the wheelset axle, technical diagnostics, nondestructive testing, ultrasonic testing, echo pulse method, time sensitivity adjustment

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