Main hazard of train wheels and its detection method

Railway rolling stock wheels are extremely important components to ensure the safe operation of trains, and they play the role of bearing and guiding. In the event of a problem with the wheel, it will cause the wheel to break, cut the shaft, and further cause a major traffic accident. Therefore, how to detect the wheels and ensure the safety of the wheels is essential.

First, the main types of dangerous defects of railway locomotive wheels

1. Cleft palate

When the train is running, a certain depth range (10 mm~20 mm) under the wheel contact surface is the largest distribution area of the wheel-rail contact shear stress. If there are metallurgical defects such as non-metallic inclusions in the area, the inclusions are under shear stress. It will become a source of fatigue cracks, and then the fatigue cracks will continue to expand. Wheel-rail contact shear stress is inherent in wheel alignment during train operation. When the crack source nucleates and promotes crack initiation under shear stress, the faster the train runs, the faster the crack propagation will be. When the crack develops to a larger extent In the rapid expansion phase of the size, the crack will develop to the outer side, inner side or tread of the rim. If it is not found in time, the wheel will be “dropped”. This type of defect is called splitting.

It can be clearly seen from the open splitting defect that the cracking defect has a fatigue source and a fatigue expansion process (shell-like crack). From the development of the cleft, it extends in the circumferential direction of the wheel and is therefore called a circumferential defect.

2, wheel crack

Due to abnormal strong braking, metallurgical defects in the wheel or manufacturing process defects, the wheel is radially cracked, which may cause train subversion accidents during train operation.
The wheel crack is along the diameter of the wheel and is called a radial defect.

Second, the wheel defect ultrasonic flaw detection process

1. Detection of circumferential cracks

According to the principle of ultrasonic flaw detection, when the ultrasonic wave is perpendicular to the crack surface, the ultrasonic reflection energy is the largest. Ultrasonic waves are incident perpendicular to the circumferential defect when incident radially in the wheel. Therefore, the circumferential defect of the wheel is detected using ultrasonic radial incidence.
 
 

2. Detection of radial defects

Detection using conventional ultrasonic transverse waves发送反馈