Waveform characteristics When there is no defect in the spring, the ultrasonic wave is reflected multiple times inside the spring to form an ultrasonic channel in the spring. The ultrasonic wave will always propagate to the lower end surface and be received by the probe. Only the initial wave and the lower surface angular wave are on the instrument, if it is in the spring. If there is a defect, part of the acoustic wave is reflected back by the defect during the propagation of the ultrasonic wave, and is received by the probe to form a defect wave. The other part of the acoustic wave continues to travel forward to the lower end of the spring to form a lower end face angle wave if there is a serious defect in the spring or If the material is poor, all the sound waves in the ultrasonic wave are reflected or scattered by the defect. The sound wave cannot continue to travel forward to the lower end of the spring. The initial wave and the defect wave are displayed on the instrument.
Ultrasonic testing springs should pay attention to the problem using ultrasonic testing springs should pay attention to the following issues: 1 due to locomotive second spring length of 7.8m, ultrasonic flaw detector transverse wave flaw detection range must be adjusted to greater than or equal to 7.8m, so the analog instrument can not be used to detect For springs, a digital ultrasonic flaw detector with a transverse wave flaw detection range of more than 8m must be used. 2 The quality of the spring is detected with this method with high accuracy, and the missed detection rate is small. However, in the detection, the ultrasonic wave forms an ultrasonic channel after multiple reflections. In the spring, there are both transverse wave and surface wave, so there is a certain error in the defect location. .
Improvement measures 1 It is necessary to ensure that the dynamics of the branches of each bridge arm of the locomotive rectifier cabinet are well balanced, and the positive characteristics of the triode thyristors must be as uniform as possible. Therefore, the strict selection of each component is required when the locomotive rectifier cabinet gets off the train. , Detect the components of the positive and negative characteristics, pressure drop and other parameters, according to the detection results of the assembly, so that the characteristics of the basic components of the same assembly in the same bridge arm. At the same time, the current sharing test of each bridge arm shall be carried out. The maximum and minimum current sharing coefficient must be greater than 0.85. The arm of this requirement cannot be reached. Replace the silicon element and adjust it until it meets the requirements. When the locomotive is minor repaired, the current sharing coefficient is tested on the bridges of the full-control bridge of the rectifier cabinet of the vehicle with a portable current-equalizing tester, and the replacement components less than 0.85 are adjusted. 2 Add pulse connection on the thyristors of each bridge arm to eliminate individual thyristors from triggering when the original wiring is not properly crimped. (3) In daily minor and minor repairs of locomotives, the resistive state of the traction winding RC over-voltage protection components, surge absorbers, and each pulse box shall be tested to deal with defective components in time. 4 Regularly flush the side wall screen of the locomotive, and use a vacuum cleaner to dust the ventilation duct of the rectifier cabinet to ensure that the rectifier cabinet is well ventilated. The hot weather requires the locomotive crew to put the silicon fan into operation when the driver controller is no more than 3 digits. It must not be turned off to ensure good ventilation of the rectifier cabinet.
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