Study On Ultrasonic Testing Technology Of RD₂ Type Wheel Of Rail Vehicles

With the development of railway transportation towards the direction of high speed and heavy load, as well as the extension of the maintenance kilometers of car depots, the running gear for rail vehicles are required higher quality. Wheel is one of the most important component of bogie, which play a role in transmitting the static loads and traction to the steel rail during the running. In addition, it is a component with a complicated stress condition and the severe condition of the work, and also rigid withstand the perpendicular and horizontal acting force from rail joint, turnout and uneven circuit. No matter what structure form the wheel set use, as the continuous improvement of running kilometers of rail vehicles, the axle will generate the fatigue source finally due to the fatigue and extend to form the fatigue crack. The application of ultrasonic detection technology is an important aspect to ensure the safety operation. Ultrasonic testing is applied to fatigue area of the wheel axle in order to find whether the axle generates fatigue cracks and its development, to timely obtain the status of wheel axle and take measures to ensure the safety of railway transportation, which is of great significance to the people and the country.In this paper, the research object is RD₂ type of the wheel set of railway wagons, according to its fatigue corrosion cracks and the position and morphological characteristics of press-fit defects, based on the analysis of limitations of regular NDT techniques, material object contrast block for RD₂ overhaul wheels and the dedicated ultrasound probe for overhaul wheels are designed and manufactured. A variety of testing schemes are used for detecting the fatigue corrosion cracks and press-fit defects of the RD₂ overhaul wheels of the rail vehicles, and the magnetic particle testing method is used for verification. The results show that the best ultrasonic testing process for RD₂ overhaul wheels of rail vehicles is: simply apply the magnetic particle testing method for the unloading tank parts of overhaul wheels at the back bearing state; on the contrary, testing from the axial end surface by the use of the deformation of shear wave of longitudinal wave probes with the small angle or the secondaries of shear wave angle probe. For the fatigue corrosion cracks on the lateral inlaid part and the press-fit strain defects, the best testing scheme is : if for overhaul wheels of the removable bearings, using the primary reflection of 40°shear wave probe for the testing from the outer surface of the cross-rod, if necessary, confirming the defects from the axial end surface supplemented by the small angle probe; if for overhaul wheels of the non-removable bearings, using the primary reflection of the small angle probe for the testing from the axial end surface, if necessary, confirming the defects from outer surface of the axle body supplemented by the shear wave probe of big angle. For the fatigue corrosion defects inside the inlaid part and the arc transition part, the best testing scheme is : using the primary reflection of 40°shear wave angle probe for the testing from the surface of axle body, if necessary, confirming the defects from the axial end surface supplemented by the small angle probe. The study solves the deficiencies in the current ultrasonic testing method and process for the rail vehicle wheels, laying the foundations for the perfection of ultrasonic testing process method for the axle shaft, the improvement of the testing process and level, as well as the promotion and application of the process.