JPS5845139B2 - All-round radiation type X-ray tube - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD This invention relates to a full-circle radiation type X-ray tube.

In general, all-round radiation type X-ray detectors are used to inspect steel pipes for the presence or absence of welds and other defects using the so-called transmission inspection method, and are installed at the center of the steel pipe and emit X-rays in 360° directions. I'm in the middle of the day.

Most of these all-round emitting X-ray tubes are fixed anode X-ray tubes.
There are two types of anodes, or targets, in conventional all-round radiation type X-ray tubes, as shown in FIGS. 1a and 1b.

That is, a in FIG. 1 shows an all-round radiation type X-ray tube 2 disposed inside a steel pipe 1, and this X-ray tube 2 has a flat target 3, and a plane perpendicular to the tube axis. Target 3 with
X-rays 4 are emitted as shown in the figure.

In the figure, 5 is a cathode and 6 is a film.

In this case, since the X-rays 4 obliquely pass through the welded portion 7 of the steel pipe 1, it becomes difficult to see the defect image of the welded portion 7, and the defect detection accuracy decreases.

The end of FIG. 1 shows a full-circle radiation type X-ray tube 9 disposed inside the steel pipe 8, and this X-ray tube 9 has a conical target 10. is a cathode, and 12 is a film.

In this case, the X-rays 14 can be radiated perpendicularly to the welded portion 13, thereby improving detection accuracy.

However, a problem arises in that the X-ray dose distribution changes depending on the shape and position of the focal point.

That is, it is safe to have a circular focal point, and if it is rectangular like a general X-ray tube, the amount of X-rays will be large in the long side direction and small in the short side direction.

Also, if the center of the focus does not hit the apex of the cone of the target, this will also cause a difference in the X-ray dose.

The object of the present invention is to provide a new type of all-round radiation type X-ray tube that eliminates the above-mentioned conventional drawbacks.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The all-round radiation type X-ray tube of the present invention is constructed as shown in FIG. A stator 18 is disposed outside the enclosure 15 in correspondence with the cathode structure 17.

In this case, the anode structure 16 is fixed, but the cathode structure 17 is rotatable.

That is, when the cathode assembly 17 is enlarged, it becomes as shown in FIG. 3, and a coiled directly heated filament 21 is placed inside the focusing groove 20 provided in the focusing electrode 19, and the end thereof is connected to the focusing electrode. It is electrically connected to 19.

The other end passes through the focusing electrode 19 in an insulated state and is electrically connected to an inner rotor (described later).

The lower end of the focusing electrode 19 is connected to a cylindrical outer rotor 22.
is integrally fixed and supported.

Inside this outer rotor 22, an inner rotor 23 in the form of a covered cylinder is coaxially arranged near the MiJ memo bundle electrode 19. 22Q
) are partially connected.

Furthermore, a cylindrical stator 25 is disposed inside the outer rotor 22 along its axis, and its lower portion is fixed to the vacuum envelope 15 via a sealing portion 26 .

The stator 25 is made up of a cylindrical conductor 27, an insulator 28, and a conductor 29, and a portion thereof is located inside the inner rotor 23.

The inner rotor 23 is held by a bearing device 30 in contact with the conductor 27, and the outer rotor 22 is held by a bearing device 31 in contact with the conductor 29.

Note that the conductor 29 is connected to the terminal A.

Moreover, a rod-shaped conductor 32 is provided inside the stator 2-5 along the axis.
is arranged, one end is electrically connected to the conductor 27, and the other end is connected to the terminal B.

During operation, an AC voltage is applied to both terminals A and B, but the current is terminal A → conductor 29 → bearing device 31 → outer rotor 22 → focusing electrode 19 → filament 21 → inner rotor 23 → The flow follows the path of bearing device 30 → conductor 27 → rod-shaped conductor 32 → terminal B.

Incidentally, the cathode assembly 1γ having the above-mentioned configuration has a stator 18.
It rotates by electromagnetically coupling with the rotating anode type, but the rotation speed does not need to be as high as 3,000 rpnn like the rotating anode type.
It may be 0 rpm to 1 rpm.

Of course, there is no problem even if it rotates at high speed.

Also, in order to reduce the frictional resistance during rotation, the number of bearings in the bearing device 30, 31 may be increased,
It's a good idea to add plush in appropriate places.

The all-round radiation type X-ray tube of the present invention is constructed as described above and shown in the drawings, and even though the anode structure 16 is fixed, the cathode structure 17 rotates, so that the focal point shape of the target of the anode structure 16 is rectangular. Even if the cathode structure 1T rotates once, the X-ray dose becomes uniform in all directions, even if it is not coaxial with the target tip.

Therefore, the above-mentioned drawbacks of the conventional method are eliminated, and the present invention is extremely suitable for use in inspecting the presence or absence of defects in the internal joints of steel pipes and other areas.

As explained above, according to the present invention, it is possible to provide an all-round radiation type X-ray tube with great practical value.

[Brief explanation of the drawing]

Figures 1a and b are cross-sectional views showing how steel pipes are inspected using two types of conventional all-round radiation type X-ray tubes, and Figure 2 is an all-around radiation type X-ray tube according to an embodiment of the present invention. FIG. 3 is a sectional view showing the end portion (cathode structure) of the all-round radiation type X-ray tube of FIG. 2. 16... Anode structure, 1-7... Cathode structure.

Claims (1)

[Scope of Claims] 1. A full-circle radiation type X-ray tube in which an anode assembly and a cathode assembly having a filament are disposed facing each other within a vacuum envelope, wherein the anode assembly is located inside the vacuum envelope. An all-round radiation type X-ray tube, wherein the cathode structure is rotatably provided through a pair of bearings, and a current is supplied to the filament through the pair of bearings.