JPS59221949A - Rotary anode x-ray tube - Google Patents

Abstract

PURPOSE:To lengthen a life of a ball bearing with low friction torque for improved performance and a long life by arranging an evaporating lubrication member with high vapor tension and a lubrication property as well in the position near a rotary member or a ball bearing of an axis besides having higher temperature than the ball bearing. CONSTITUTION:When an evaporation lubrication member 12, for instance, silver is covered by the mounting part 4a of an axis 4, while the opening end 4b of said mounting part 4a faces the ball and still its area is narrowed, the direction of progress of the generated evaporation silver molecules is limited to the direction of the ball bearing 5. That is to say that silver molecules are evaporated in the free direction while making straight movement so as to rebound or to stick to in case of an existing wall in front and to finally fly out from the opening end 5b of the mounting part 4a solely toward the ball bearing 5. In this way, a silver lubrication film can be constantly formed on the ball bearing 5 when using an X-ray tube. Thereby, the ball bearing 5 is coated with the silver lubrication film whenever the X-ray tube is used even when the silver lubrication film is worn out thus making it possible to use the ball bearing for a long time under the best condition.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to bearing lubrication technology for rotating pickled X-ray tubes.

[Background of the invention]

FIG. 1 shows a conventionally known rotating anode X-ray tube. The structure and 1aIJ construction will be briefly explained according to FIG. An anode target 1, which is an anode member, is fastened to one end of a drive motor rotor 3v, which is a rotating member, and a shaft 4 is fastened to the other end. It is rotatably supported. The ball bearing 5 is a bearing support member 6
A part of this bearing support member 6 and the glass tube 8 are held together.
The entire rotating body consisting of the drive motor rotor 3, the anode target 1, and the shaft 4 is covered in a shape A, and a cathode body 2 serving as a cathode member is provided opposite the lever target 1, and this cathode body 2 is fixed inside the glass tube 8.

Inside, there is a cathode body 2 and a rotating anode target (1).
The glass tube 8 having the above structure is called a rotating anode x3 tube (hereinafter referred to as an X-ray tube).

A motor stator 7 serving as a magnetic field generator is provided on the outer periphery of the glass tube 8, and by generating a rotating magnetic field, the drive motor rotor 3 of the XfIM tube and the anode target 1 integrated therewith are
It rotates with business luck of 3,000 r to 9,000 f.

When thermoelectrons are emitted from the cathode body 2 to the anode target 1 at high speed, X-rays are generated from the surface of the anode target 1 in the direction of the arrow in the figure. At this time, the anode target 1 is rapidly heated by the injection of thermoelectrons, and the average temperature of n1 reaches a maximum of 140.
It becomes 0C. On the other hand, the inside of the glass tube 8 is 10""t
Since it is kept airtight in a high vacuum of less than Orr, most of the heat is radiated to the outside. However, anode target 1
A part of the heat is transferred to the shaft 4, ball bearing 5, and bearing support member 6 by conduction, so that the ball bearing 5 has a maximum temperature of 550C.
is heated to.

Therefore, lubrication technology becomes the most important issue in developing and manufacturing pipes. As is well known, under this condition,
Ordinary lubricating oils (including grease) cannot be used at all because they evaporate or deteriorate.On the other hand, metal surfaces become clean in high temperatures and high vacuums, so they tend to stick to each other, making friction and sliding parts easier. To prevent the ball bearings from seizing and sticking, the ball bearings 5 must be lubricated, and are lubricated with a stable solid that does not evaporate or deteriorate even under these conditions.Solid lubricants for X-ray tube ball bearings include silver, lead, etc. Soft metals and nonmetallic solid lubricants such as MO82 and wse2 are generally used.

These lubricant films are coated on the balls or the transfer surface of the ball bearing 5 to prevent direct contact between the balls and the transfer surface, thereby preventing seizure. Conventionally known techniques for coating the balls or inner and outer rolling surfaces of the ball bearing 5 with a solid lubricant are as follows. Soft metals such as silver and lead are electroplated and ion brated.

The coating may be applied by dipping, sputtering, vapor deposition, or "rubbing" using the apparatus shown in FIG. 2, for example. In the apparatus shown in FIG. 2, a plurality of ball bearings 5 are arranged in a glass container 81 kept at a vacuum and high temperature similar to that in the X-ray tube, and a metal 9 to be coated is arranged in the center of a divided inner ring 52. and rotate the outer ring 53 and the bearing box 54. During rotation, the metal 9 and the ball 51 roll into contact, and a film of the metal 9 is gradually formed on the surface of the ball 51 and the transfer surface of the outer ring 530.Then, the ball 51 and the outer ring 53 are transferred to the X-ray tube ball bearing 5. Incorporate into.

In the method shown in Fig. 3, an iron wire 1.0 with a U-shaped cross section is provided at the position shown inside the X-ray tube, and metals that easily evaporate, such as barium (Ba), zinc (Zn), and chromium ( During the manufacturing process of the X-ray tube, the wire 10 is heated with a heating power source 11 to remove easily vaporized metals such as Cr).
For example, Ba is evaporated.

Since the ball bearing 5 is rotating, the evaporated metal is uniformly coated over the entire surface of the ball.

Non-metallic solid lubricants such as MO82 are sputtered and coated9. Baking with an inorganic binder can be done by coating the ball surface or rolling contact, or by incorporating these solid lubricants into the bearing cage to coat the ball surface with a lubricating film during friction between the cage and the balls. . Combining the data so far, non-metallic solid lubricants such as MO82 have the advantage of reducing bearing torque due to their small coefficient of friction, but they wear easily and the front part of the lubricating film is short, and wear particles are transmitted to the X-ray tube. This has the disadvantage that it contaminates the inside of the bulb and prevents the generation of X-rays.

For this reason, soft metals are mainly used, which have a slightly higher friction, but are resistant to wear and have a long coating life.

Conventionally, ball bearings coated with a lubricating film are used in the X-ray tube, but since soft metal lubricants have extremely poor fluidity compared to normal lubricating oils, the film may form locally. However, the ability to repair it when it wears out is almost non-existent. Also, wear is unavoidable. To compensate for these drawbacks, thickening the coating increases frictional torque, vibration, and noise due to the deformation resistance of the soft metal, or even accelerates wear, resulting in long life, stable, and low-noise rotation. An anode X-ray tube is not available.

[Purpose of the invention]

The purpose of the present invention is to provide a rotating anode X-ray tube that can improve performance and extend the life of the ball bearing by coating the ball bearing with a soft metal at any time during use of the X-ray tube, thereby making the ball bearing have a long life with low friction torque. is to provide.

[Summary of the invention]

A feature of the present invention is that an evaporative lubrication member with high vapor pressure and lubricity is disposed near the rotating member or the ball bearing of the shaft, and at a higher temperature than the ball bearing. be.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. Fourth
The figure shows an embodiment of the X-ray tube of the present invention.

The mounting of the shaft 4 with the drive motor rotor 3 is difficult because the portion 4a has a cylindrical thin-walled structure which increases thermal resistance. It has been confirmed through calculations that it will reach a maximum of 6,500. To attach the shaft 4, a silver washer 12 serving as an evaporative lubricating member is attached to the portion 4a. Note that the method of attaching the washer 12 is not limited to welding, and mechanical fastening may also be used as long as a close contact with the portion 4a is achieved. Silver, like other metals, has a high vapor pressure at high temperatures, and according to the experimental data shown in Figure 5, at 650C, the vapor pressure
The evaporation rate is about 10 times that of 0c. Therefore, when the X-ray tube is used, the temperature of the p-ball bearing 5 increases due to transmission from the target 1, and the evaporation rate of silver molecules generated from the washer 12 increases at the time when lubrication is most needed. Evaporated molecules move in a straight line, so if there is a barrier in front of them, they will collide with the wall and either bounce off or stick to it. Therefore, as shown in the partially enlarged view of the vicinity of the evaporative lubrication member 12 in FIG. 4 and in FIG.
When the opening end 4b of the portion 4a faces the ball bearing 5 and its area is narrowed, the traveling direction of the generated evaporated silver molecules is limited only to the direction of the ball bearing 5. That is,
Although the silver molecules evaporate in any direction, they move in a straight line, so if there is a wall in front of them, they bounce off but stick to it, and eventually fly out only toward the ball bearing 5 through the opening FJ5b of the mounting portion 4a. In this way, a silver lubricating film can be constantly formed on the ball bearing 5 when the X-ray tube is used. Since the pressure bearing 5 is rotating,
Silver molecules are uniformly coated over the entire surface of the ball. The rate at which evaporator molecules adhere to the ball bearing 5 is extremely slow, and even if the attached portion 4a is held at 65 oc for one hour, the thickness of the molecules that adhere to the ball bearing 5 is about 0.01 μm. Note that the adhesion thickness here is based on the case where the ball bearing 5 is a total pressure bearing with a shaft diameter of 6wn. However, as long as the solid lubricant film is uniformly coated, it can exhibit the groove opening effect even if it is thin, and o or oi μm is sufficient. On the other hand, the thinner the bearing, the better the surface precision of the contact area between the balls of the ball bearing 5 and the raceway surface, the higher the load carrying capacity, and the lower the deformation resistance of the soft metal lubricating film, which reduces the resistance of the rollers 9. , the friction torque becomes smaller. Furthermore, since the lubricating film is thin and uniform, it is effective in reducing rotational vibration and noise.

Therefore, according to this embodiment, even if the silver lubricating film is worn out,
Since the silver lubricating film is coated on the ball bearing 5 each time the wire tube is used, the ball bearing 5 can be used in the best condition for a long period of time.

As another embodiment of the present invention, if the ball bearing 5 is coated with a thin film of silver in advance, good lubrication performance can be obtained from the beginning of use, and furthermore, the adhesion force of the evaporator molecules to the ball surface is increased. Lubrication life is extended. This is the same metal,
That is, this is because the bonding force between silver and silver is the strongest compared to other combinations.

FIG. 7 shows another embodiment of the invention. The installation of shaft 4 is part 4.
A washer 12 that serves as an evaporative lubrication system is bath-bonded and formed, and the part 4a covers the inner diameter and outer diameter of the silver washer 12, and its openings yiiiA4b are two, and the opening end 4b is
The side closer to the ball bearing 5 is made smaller.

Therefore, the flow t of the evaporated silver molecules is further narrowed down by the two openings, and the directivity of the evaporated iron molecules toward the ball bearing 5 is further improved.

In yet another embodiment of the present invention, the washer 12 is made of barium (
It is made of an alloy of so-called getter materials such as Ba), magnesium (Mg), titanium ('I'i), and silver. The getter is oxygen (02) and nitrogen (N2).

It absorbs all the constituent gas components of the desired air, such as moisture (1-120) and carbon dioxide (CO2), and works to increase the degree of vacuum.

However, getters require heating to begin their action, and all begin operating at approximately 5000-800C. Of these, Ba and Mg are evaporative getters that evaporate themselves to form an evaporated film and not only absorb the aforementioned gases, but it is clear that the film formed on the ball bearing 5 has good lubricity. It is being done. According to this embodiment, the lubrication performance of the ball bearing 5 can be improved over a long period of time, and the inside of the X-ray tube can be maintained at a high vacuum.

Next, an example in which lead PB is used as a lubricant for the ball bearing 5 will be described. As shown in FIG. 8, the washer 12 is made of an alloy material exhibiting a texture of lead and copper or lead and iron. This material can be easily manufactured by powder metallurgy, but the manufacturing method is not limited.

Lead has a low melting point of 327C, and when heated above this temperature it melts and exhibits fluidity, and if the washer 12 is made of only lead, it cannot be heated to a temperature that generates a large amount of steam. However, as shown in Figure 8, copper (Cu, melting point 1083C)
If iron (Fe, melting point 1535C) forms the skeleton of the washer 12, the original shape will be maintained even if the lead is melted, so the upper limit heating temperature can be increased.

According to FIG. 5, the amount of evaporation of lead is greater than that of silver, so in this example, a lead film can be formed on the ball bearing 5 at a lower temperature, and a lubricating film can be formed in a shorter time than with silver at the same temperature. It will be done.

FIG. 9 shows another embodiment. The amount of lubricant coated on the ball bearing 5 is increased by narrowing the diameter of the open end of the drive motor rotor 3 to prevent evaporated metal from flowing out of the anode. This embodiment also has the effect of preventing the inner wall of the glass tube from being contaminated by evaporated metal.

FIG. 10 shows an example in which the present invention is implemented in an X-ray tube with a rotating outer ring structure. The ball bearing 5 is attached to the drive motor rotor 3 with a heat resistance section 3a.
The washer 12 is installed at the innermost end of the drive motor rotor 3. The temperature of the washer 12 can be maintained approximately 150C higher than that of the ball bearing 5 by the thermal resistance portion 3a.

〔Effect of the invention〕

Frictional torque and vibration of ball bearings according to the invention.

It is possible to reduce noise, extend the life of the X-ray tube, and increase the degree of vacuum inside the X-ray tube, which is effective in improving the performance and extending the life of the X-ray tube.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of a conventional rotating pickle X-ray tube, Figure 2 is a schematic cross-sectional view of a conventional ball bearing lubricating film coating device, and Figure 3 is a schematic cross-sectional view of a conventional ball bearing lubricating film coating device. Cross-sectional view, Figure 4,
6, 7, 9, and 10 are partial vertical cross-sectional views of the rotating anode X-ray tube of the present invention, FIG. 5 is an evaporation rate diagram of silver and lead in a vacuum high temperature atmosphere, and FIG. The figure is an assembly diagram (b) of a washer (a) which is a component of the present invention. 3... Drive motor rotor, 4... Shaft, 5... Ball bearing, $2 figure $3 K figure 5 figure 5 /L T('c)

Claims (1)

[Scope of Claims] 1. A cathode member, an anode member disposed opposite the anode member, a rotating member integrally formed with the anode member, a bearing device that rotatably supports the rotating member, and a bearing device of the bearing device. In a rotating anode X-ray tube configured in a true nitrogen shape, the four members are covered with a bearing support member that fixes a stationary part, a part of this bearing support member and a container, and the rotating member is adjacent to the bearing device. A rotating anode X-ray tube characterized in that an evaporative lubricating member having a higher vapor pressure and lubricating property than the material of the rotating member is disposed at a position where the temperature is higher than that of the bearing device. 2. The inner diameter and outer diameter of the evaporative lubrication member are covered by the rotating member, the open end of the rotating member faces the bearing device, and the inner diameter and outer diameter of the open end are larger than those at other positions. 2. The rotary anode X-ray tube according to claim 1, wherein the outer diameter of the rotary anode X-ray tube is made small so that the area of the opening end is smaller than that of the evaporative lubrication member. 3. By providing a plurality of open ends of the rotating member that share the inner diameter and outer diameter of the evaporative lubrication member, and making the inner diameter and outer diameter smaller in order of proximity to the bearing device. A rotating anode X-ray tube, characterized in that the area of the open end is made smaller closer to the bearing device. 4. The rotating anode X-ray tube according to claim 1, wherein the bearing device is coated with a thin film of silver or lead, and the evaporative lubricating member contains silver or lead. 5. The rotating anode X-ray tube according to claim 1, wherein the evaporative lubricating member contains barium or zirconium. 6. The rotating anode X-ray tube according to claim 1, wherein the open end on the outer peripheral side of the bearing support member of the rotating member has a diameter smaller than that at other positions.