Common X-ray Tube Failure Analysis
Failure 1: Failure of the rotating anode rotor
(1) Phenomenon
① The circuit is normal, but the rotation speed drops significantly; the static rotation time is short; the anode does not rotate during exposure;
② During exposure, the tube current increases sharply, and the power fuse is blown; a certain point on the anode target surface is melted.
(2) Analysis
After long-term work, the bearing wear and deformation and the clearance change will be caused, and the molecular structure of the solid lubricant will also change.
Fault 2: The anode target surface of the X-ray tube is damaged
(1) Phenomenon
① The X-ray output decreased significantly, and the sensitivity of X-ray film was insufficient; ② As the anode metal was evaporated at high temperature, a thin metal layer can be seen on the glass wall;
③ Through the magnifying glass, it can be seen that the target surface has cracks, cracks and erosion, etc.
④ The metal tungsten splashed when the focus is severely melted may burst and damage the X-ray tube.
(2) Analysis
① Overload use. There are two possibilities: one is that the overload protection circuit fails to overload one exposure; the other is multiple exposures, resulting in cumulative overload and melting and evaporation;
② the rotor of the rotating anode X-ray tube is stuck or the start-up protection circuit is faulty. Exposure when the anode does not rotate or the rotation speed is too low, resulting in instantaneous melting and evaporation of the anode target surface;
③ Poor heat dissipation. For example, the contact between the heat sink and the anode copper body is not close enough or there is too much grease.
Fault 3: X-ray tube filament is open
(1) Phenomenon
① No X-rays are generated during exposure, and the milliamp meter has no indication;
② The filament is not lit through the window of the X-ray tube;
③ Measure the filament of the X-ray tube, and the resistance value is infinite.
(2) Analysis
① The voltage of the X-ray tube filament is too high, and the filament is blown;
② The vacuum degree of the X-ray tube is destroyed, and a large amount of intake air causes the filament to oxidize and burn quickly after being energized.
Fault 4: There is no fault caused by X-ray in photography
(1) Phenomenon
① Photography does not produce X-rays.
(2) Analysis
①If there is no X-ray generated in the photography, generally first judge whether the high voltage can be sent to the tube normally, and directly connect the tube.
Just measure the voltage. Take Beijing Wandong as an example. Generally, the primary and secondary voltage ratio of high-voltage transformers is 3:1000. Of course, pay attention to the space reserved by the machine in advance. This space is mainly due to the internal resistance of the power supply, autotransformer, etc., and the loss increases during exposure, resulting in a drop in the input voltage, etc. This loss is related to the selection of mA. The load detection voltage should also be higher. Therefore, it is normal when the voltage measured by the maintenance personnel exceeds the value within a certain range other than 3:1000. The exceeding value is related to the selection of mA. The greater the mA, the greater the value. From this, it can be judged whether there is a problem with the high-voltage primary circuit.
Post time: Aug-05-2022