JPS58216347A - Rotary anode x-ray tube device - Google Patents

Abstract

PURPOSE:To obtain an oscillation attenuator with high reliability by constituting facing portions of a movable body outer surface and a ring inner surface in a curved shape respectively so as to form a clearance which is extremely easy to adjust its size. CONSTITUTION:An oscillation attenuator 20a is formed by utilizing the flow of insulation oil 15 through a fine curved conical cylindrical clearance g' constituted with a movable body 18a having an outer curved surface and a ring 19a having an inner curved surface of the same shape. The clearance g' in the tube axis direction between the movable body 18a and the ring 19a can be easily adjusted by inserting a spacer 21 between an anode supporter 11a and the movable body 18a. In addition, by properly selecting the thickness of the spacer 21 for use in response to the size deviation in production of the anode supporter 11a, movalbe body 18a, and ring 19a, the clearance g' with a fixed size value can be available and the degree of oscillation attenuation can be easily adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating anode X-ray tube device, and more particularly to an improvement in a vibration damping device (oil film damper) for an X-ray tube.

FIG. 1 is a cross-sectional structural diagram showing an example of a conventionally proposed rotating anode X-ray tube device. In the figure, an anode target 2, which is an anode member, is fastened to one end of a drive motor rotor 1, which is a rotating member, and a shaft 3 is fastened to the other end. A drive motor rotor 1. The entire rotating body including the anode target 2 and shaft 3 is vacuumed, and a cathode body 1 serving as a negative member is provided on the surface facing the anode target 20, and this cathode body 7 is fixed in a glass tube 6. has been done. In this case, a glass tube 6f in which a cathode body 7, a rotating anode target 2, etc. are assembled, a rotating anode
It is called a Xia tube (hereinafter referred to as Xia tube). This xfJJ tube is fixed within the housing 8. That is, a frame 9 is provided at the side end of the housing 8, and a support body 11 is fixed to the side end of the frame 9 by a presser ring 10. One end of the X-ray tube is fastened to the support 11 with a bolt 12, and the other end of the X-ray tube is supported by the housing 8 via a tube support 13.

On the other hand, the frame 91C is provided with a motor stator 14 serving as a magnetic field generator, and generates a rotating magnetic field to drive the X-ray tube drive motor rotor 1 and the anode target 2 integrated therewith.
is 3000-9000 r, p, m.

rotated at a high speed. When X-rays are generated, a high voltage is applied between the cathode body 7 and the anode target 2.
Insulating oil 15 is sealed within the housing 8 to improve overall electrical insulation.

Note that 16a is attached to the frame 9, and 16o is attached to the support body 11.
a hole for inflowing insulating oil 15 provided in each of the holes;
17a and 17'o are lead wire connectors.

In the rotating anode X-ray tube device configured as described above, when an electron beam is emitted from the cathode body 7 to the anode target 2, it moves from the surface of the anode target 20 in the direction rI indicated by the arrow in the figure.
CX-rays are emitted. At this time, the average temperature of the anode target 2 is about 1200° C., and since the inside of the glass tube 6 is kept airtight in a high vacuum, most of the heat is radiated and transferred to the outside.

However, some of the heat of the anode target 2 is transferred to the axis 3. The heat is transferred to the ball bearing 4 and the bearing box 5, and at this time the ball bearing 4 reaches a temperature of about 500°C. For this reason,
Considering thermal expansion for ball bearing 4, the bearing clearance is 30 to 60μ.
m (5 to 10 μm for normal electric motors) is used. Therefore, when the anode target 2 is operated at room temperature in the initial stage of rotation, the gap between the ball bearings 4 is large, so that the anode target 2 causes unstable rotational vibrations and generates large rotational noise.

Particularly in a critical speed range where rotational vibration rapidly increases, an abnormal load is applied to the ball bearing 4, which often causes early damage.

Therefore, as a method for reducing the dynamic load acting on the ball bearing 4, Japanese Patent Publication No. 45-12162 was published in Japanese Patent Application Laid-Open No. 49-577.
No. 86 and Japanese Unexamined Patent Publication No. 49-44691 propose a structural system in which the support rigidity of the rotating system is lowered to set the critical speed at a lower speed.

These proposals lower the critical speed of the rotating system, and improve the ball bearing 4.
Although this is effective in reducing the total dynamic load due to the applied texture imbalance, it is not sufficient to prevent damage to the ball bearing 4 when considering the entire speed range.

This is because, according to actual measurement results of the rotational vibration characteristics of the X-ray tube, even in an elastic support structure, rotational vibration rapidly increases in the high-speed region C after passing the critical speed, resulting in unstable vibration characteristics. It became clear. In addition, vibration damping elements are placed around the bearings for normal vibration isolation designs for high-speed rotating machines.
Absorbs abnormal or unstable vibrations. However, as mentioned above, the X-ray tube has a special atmosphere such as high vacuum and high temperature conditions, and therefore a normal damping device using an oil film damper or vibration-proof rubber cannot be used inside the X-ray tube. Although solid friction dampers can be used, they have the drawback that the high temperature and high vacuum conditions cause galling on the friction surface and the function deteriorates early. Such vibration isolation of the anode target 2 is necessary to extend the life of the ball bearing 4 and to reduce rotational noise. However, especially when the vibration of the anode target 2 becomes large, it causes the X-rays to become out of focus, so it is not enough. Not only is this a problem in that poor image quality cannot be obtained, but in the case of a microfocus, excessive vibration of the anode target 2 has become a fatal defect in X-ray photography.

In order to overcome these drawbacks, a rotating anode X-ray tube having a structure shown in a cross-sectional view of a main part in FIG. 2 has been proposed. That is, in the same figure, the anode support 11a fixed to the frame 9 with the presser ring 10 is designed to have optimal rigidity according to the plate thickness t. In this case, the rigidity of the support 11a can be determined not only by the plate thickness but also by providing slits in the support 11a. Further, a bearing box 5 is connected to one center of the support 11a, and a movable body 1B is connected to the other. A ring 19 is disposed across the outer periphery g2 of the movable body 18, and the vibration damping device 20 uses the flow of the insulating oil 15 in the minute cylindrical gap g formed between the movable body 18 and the ring 19. is configured. That is,
This vibration damping device 20 is an oil film damper that utilizes the squeezing action of the insulating oil 15. As shown in the figure, the housing 8 is filled with the insulating oil 15, so that the movable body 18 is When it vibrates, pressure is generated in the rotary cylindrical gap g made up of the movable body 18 and the ring 19, and the insulating oil 15 in the gap g moves in the tube axis direction and its circumferential direction, so the vibration energy is transferred to the gap. Where will it be absorbed?

The vibration absorption effect of this oil film damper increases in proportion to the vibration speed of the movable body 18, so the vibration transmitted from the rotating system to the bearing box 5 is absorbed by the damping device using the oil film damper described above via the support 11a. be done. Moreover, the support body 11. is through frame 9...Using 8
Since external vibrations are also absorbed by the damping device, external vibrations are not transmitted to the rotating system, and the focus of the X-rays described above is stabilized. Furthermore, since the bearing box 5 is supported by the support body 11a with appropriate rigidity, the dynamic load acting on the ball bearing 4 is reduced.

However, in the rotary positive xsy device with the above configuration, the minute cylindrical gap g formed between the movable body 1B and the y-guts 9 for determining the magnitude of vibration is
Support body 11a, movable body 1B.

Since the deviation (variation) K of the dimensions of parts such as the gap 19 is determined by the deviation K, in each completed rotating anode X-ray tube device, it is possible to obtain a gap g that has a constant dimensional value with a small degree of vibration absorption. In addition, it was extremely difficult to create an adjustment chart to obtain constant dimensional values.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the conventional art, and an object of the present invention is to configure the opposing portions of the outer surface of the movable body and the inner surface of the ring into curved shapes, thereby creating a gap between the two opposing surfaces. Rotating anode
We provide wire tube equipment.

Embodiments of the present invention will be described in detail below using the drawings.

FIG. 3 is a cross-sectional view of essential parts showing one embodiment of a rotating anode X-ray tube device according to the present invention. Since the same symbols as those in the previous drawings represent the same elements, a description thereof will be omitted.

In the figure, a cone-shaped movable body 18a having a curved outer periphery is fastened and fixed with a bolt 12 via a spacer 21 at the center of the end opposite to the bearing box 5 of the anode support 11a. Further, on the outer circumference of the cone-shaped movable body 18a having a curved outer surface, a ring 19a is formed on the inner side with a curved surface substantially the same as the outer surface of the movable body 18a.
are arranged so as to surround the outer periphery of the movable body 18a. The vibration damping device 20a uses the flow of the insulating oil 15 in a minute curved conical cylindrical gap i formed by a movable body 18a having a curved surface on its outer surface and a ring 19a having a curved surface of the same shape on its inner surface. is configured.

According to such a configuration, the movable body 1 is attached to the anode support 11a.
B, t - When fixing, by inserting the spacer 21 between the anode support 11a & OJ moving body 18a,
The gap g' in the tube axis direction between the movable body 18a and the ring 19a can be easily adjusted. In addition, the solar support 11a
, by appropriately selecting and using the thickness of the spacer 21 in response to manufacturing dimensional deviations (variations) of the movable body 18a and the ring 19a), a gap g having a constant dimensional value is created.
′ can be obtained, and the degree of vibration damping can be easily adjusted.

FIG. 4 is a cross-sectional view of main parts showing another embodiment of the rotary anode X-ray tube device according to the present invention, and since the same symbols as in the previous figure represent the same elements, a description thereof will be omitted. The difference between this figure and FIG. 3 is that in FIG. On the other hand, movable body 1
The vibration damping device 20b is configured so that the outer surface of the ring 8b has a concave shape when viewed in cross section, and the inner surface of the ring 19i) has a convex shape.
ffi configuration. Even in such a configuration, the same effects as described above can be obtained.

As explained above, according to the present invention, by configuring the vibration damping device (oil film damper) to form a tapered gap between the movable body and the ring,
Since the dimensions of this gap can be adjusted easily, a gap with a constant size value with a small degree of vibration absorption can be easily formed, and a highly reliable vibration damping device can be obtained with high productivity. In addition, with this configuration, the vibrations of the entire rotating anode X-ray tube are effectively absorbed, reducing the dynamic load acting on the ball bearings, resulting in a system that can be used with stable rotational characteristics over a long period of time. However, it has extremely excellent effects such as being able to obtain high-quality X-ray photographs.

[Brief explanation of drawings]

1 and 2 are cross-sectional configuration diagrams showing an example of a conventional rotating anode X-ray tube device, FIG. 3 is a cross-sectional configuration diagram of essential parts showing an example of a rotating anode X-ray tube device according to the present invention, and FIG. The figure is a cross-sectional configuration diagram of main parts showing another embodiment of the rotating anode X-ray tube device according to the present invention. 1--Drive motor rotor, 2--Anode target, 3--Axis, 4--Ball bearing, 5--Bearing box, 6--Glass tube, T- φ... Between cathodes, 8...
War/Housing, 9...Frame, 10/1-Φ/
Presser ring, 11, 11a--Support, 12...
・Bolt, 13... Support, 14... Fist/Motor stator, 15 q... Absolute stay, 16a, 161
) ... Hole, 17a - rg 17b ... Connector, 18, 189L, 18o
-Fist...Movable body, 19, 19a, 19b@...Ring, 20° 20a, 20b @・@-Vibration damping device,
21... Spacer. Agent Patent Attorney Toshiyuki Usuda 2 illustrations and 3 illustrations

Claims (1)

[Claims] An X-ray tube is attached to one end of an anode support whose periphery is fixed to a frame inside a housing filled with insulating oil.
A rotary anode X-ray tube device comprising a vibration damping device having a movable body fastened and fixed to the other end thereof with a bolt, and a ring disposed through a minute gap between the movable body. Rotary anode