X-ray tube manufacturers: How difficult is it to develop and produce a tube?

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X-ray tube is used to produce the core components of X-ray imaging equipment, the quality of the tube, which directly affects the imaging quality of the equipment and the service life of the x-ray machine.

X-ray tube production has always been the pain point of each manufacturer, although in China there are a number of manufacturers with the production capacity of X-ray tube, but the quality of its products and some well-known foreign enterprise parts there is still a gap. How difficult is the development and production of the tube, the main difficulty in which areas?

First, the production of the tube involves a number of principles

X-ray source, the tube, we know that the radiation produced by the high-speed impact of electrons on large atoms, and the use of which the effective X-rays to penetrate the human body. However, this impact mechanism of continuous investigation, effective control, efficient use has been carried out, involving dozens of basic theories, principles and laws, requires strong theoretical background.

Second, the production of the tube involves special materials

None of the components of the tube is an ordinary component, they are all special materials. For example, the filament, both to withstand 2200-2500 ℃ high temperature, but also efficient emission of electrons, but also must be able to maintain mechanical strength at high temperatures, can withstand 40G centrifugal force, can withstand the ion bombardment is not bad, the shape of the best small, the life of the best longer, the best volatilization at high temperatures, the best small, ion adsorption is best to do not affect the electron emission to meet all of the above. Ordinary tungsten filament can not do, must be specially designed – add special raw materials, the surface must be deposited special substances, in short, a small tungsten filament must be carefully designed, well forged, not ordinary. And the anode involves more, such as target materials include tungsten, molybdenum, rhodium, rhenium, also need to weld the graphite layer to increase the heat capacity, the use of target materials under different conditions are not the same.

Third, the complexity of the process of producing the tube

In particular, the filament, which needs to be firmly welded to the column of the filament cover, requires argon arc welding. The metal core body and the glass part of the two sides need special brazing, liquid bearings need special laser inscription on the herringbone pattern, so that the liquid metal in the space of 20 microns, under the guidance of the pattern to play a zero-friction bearing role. The tube core needs a long time of exhaust before assembly, the first room temperature exhaust air, and then let the tube core in the quasi-use conditions of anode heating to 1200 ℃ to exclude adsorbed gases and ions, waiting for high-temperature stabilization of the exhaust for dozens of hours and then pinch the tube, and to maintain a certain degree of vacuum, the ideal vacuum is 10-7 Pascal.

Fourth, the use of the production of poor conditions of use of the tube

Usually the power of the balloon for 20-100kW, 100kW for example tube, its effective power is only one ten thousandth, about 10W, i.e., only one percent of the energy converted into X-rays, only about one percent of the X-rays can be effectively detected, 99.99% of the 100kW are turned into heat. Equivalent to the tube is in its own huge heat generation “hot stove” within the work of any component of the tube are harmless, so overcome high temperature, discharge heat is the focus of the tube. Furthermore, the anode speed of the tube is generally 3000-12000 revolutions per minute, and the high-speed rotation of the tube assembly together with 3-4 revolutions per second in the frame, which means that not only the centrifugal force of the anode rotor itself is very strong, but also to withstand about 40 times the acceleration of gravity (0.25s/r), a little defect will immediately destroy the tube.

Fifth, the tube of the mass production is difficult

Because of historical and development reasons, various periods, various manufacturers, various models are developed with different tube, so far the global production of tube on a few, part of it is only for their own use, never sell out. Such as Nanjing Perlove Medical, is one of the few domestic core parts manufacturers, currently has a tube, high-voltage generator of independent and manufacturing capacity, its main C-arm and DR two major products have a very high cost-effective, in recent years in the market share have achieved remarkable results.

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