JPS59691Y2 - rotating anode x-ray tube - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of the anode bearing of a rotating anode X-ray tube.

The anode bearing of the rotating anode X-ray tube, which is used as a diagnostic X-ray tube in an X-ray device and can pass a large tube current at a small focal point and provide sharp images, can be used in high vacuum and at high temperatures.
The performance of rolling bearings (mainly ball bearings) that support high-speed rotating bodies of 000 r, pm is determined by the oil-free lubrication technology.

The currently commonly used lubrication method is:
A thin film of Pb is mainly formed on the steel balls, inner and outer rings, cage, etc. of a bearing by sputtering or the like.

In addition to the above-mentioned Pb, Sn is also used as a lubricating solid material, but lubricants made of these metals with low hardness have low rotational noise at high speed rotation and exhibit good lubricity, but their melting point is low at 350 ° C or less. Therefore, in order to prevent melting and evaporation, it is necessary to take measures to suppress the transmission of the high temperature of the target to the bearing as much as possible.

This is an obstacle to improving the performance of the rotating anode X-ray tube, especially to increasing its load.

In order to solve this problem, recently developed ion blating is used to melt Au, Ag, etc.
By depositing this metal film on bearing parts, it is possible to produce a bearing with excellent lubricity without the risk of evaporation.

However, the above-mentioned metal films such as Au and Ag have the drawbacks of high hardness and high rotational noise during high-speed rotation, and also have the problem of being easy to peel off, so they are not yet used in bearings for rotating anode X-ray tubes. It is.

This idea was created in view of the above-mentioned current situation, and it solves the problem of oil-free lubrication, which is an obstacle to improving the performance of conventional rotating anode X-ray tubes, and prevents the peeling and evaporation of the lubricating solid components. The purpose of this invention is to provide an X-ray tube that can withstand heavy loads and has low rotational noise.

In other words, in a rotating anode X-ray tube in which the rotating shaft of a disk target is rotatably supported on an anode fixed base by a plurality of ball bearings provided in the axial direction of the disk target, the ball bearings located close to the disk target are made of gold. Melting point of silver etc. 800~
The friction surface of the solid lubricating member is treated with a solid lubricating member made of hard metal at a temperature of 1200°C, and the lower layer of the solid lubricating member has an ionic radius between that of iron, which is the ball bearing material, and that of gold and silver. A metal film such as copper or chromium is formed, and the friction surface of the ball bearing at a distance from the disc target is treated with a solid lubricating material made of soft metal such as lead or tin with a melting point of 200 to 400°C. Rotating anode
This applies to the wire tube.

An X-ray tube according to an embodiment of this invention will be explained below with reference to the drawings.

Figure 1 shows a rotating anode type X using ball bearings according to this invention.
1 is a cross-sectional view showing the anode structure of a wire tube. Reference numeral 1 denotes a disk target, which is tightened with a nut 3 at the tip of an anode rotating body 2.

A rotating shaft 5 is connected to the rotating body 2 by several mounting screws 4.

An inner ring is fitted to the rotating shaft 5, and a ball bearing B1 is provided at a position where the inner ring contacts the stepped portion 5A of the rotating shaft, and a rotating shaft is also provided at a position separated by an inner pipe 7 that fits into the rotating shaft 5. Ball bearing B2 with inner ring fitted to 5
The above-mentioned Bl, B
It holds two ball bearings.

The outer rings of the ball bearings B1 and B2 sandwich and support both ends of the outer pipe 10, which is concentric with the inner pipe 7.

This outer pipe 10 and the outer rings of Bl and B2 are fixed cylinders 11
After being fitted and inserted into the inner wall 11H of the recess, it is fixed with two pointed screws 12 in the right angle direction so as not to be pulled out from the fixed cylinder 11.

Reference numeral 13 is a glass tube, and a motor stator (not shown) is provided on the outer periphery of the tube to generate a rotating magnetic field to rotate the rotating body 2 at, for example, 300 Or, p, m at 60 Hz, and 9000 r, p, m at 180 Hz. be.

Is the above structure very similar to a conventional X-ray tube?
This invention is explained in Figures 2A and B and Figure 3.
The main part is the ball bearing B2.

That is, in the conventional one, both Bl and B2 were made of the aforementioned Pb or Sn as a lubricating solid film, but in this invention, first, a partial cross-section of the ball bearing B1 on the side closer to the target 1 was At A, the steel ball 20, the inner ring 21. Outer ring 2
2 by an appropriate method (including talin up by ion bombardment in an ion blating device).

Next, using only the steel ball 20 as a substrate, Cu was heated while maintaining the substrate temperature at 200 to 600°C during a gas discharge of Ar or the like at 10-2 Torr using an ion brating device.
Alternatively, Cr is used as an evaporation source, and while heating it, the substrate is used as a cathode, the evaporation source boat is used as an anode, and a DC voltage of -1 to -5 KV is applied between the two poles.

The evaporated atoms of Cu or Cr are partially ionized as they pass through the glow discharge (plasma), and are driven into the surface of the substrate by the combined force of kinetic energy due to heating and acceleration energy due to the electric field.

This is ion blating, and the substrate (in this case, the steel ball 20) can be coated with a uniform Cu or Cr film 23 over the entire surface with an arbitrary thickness in the range of 5 to 20 μm, as shown in FIG. 2B. It's Chino.

The surface layer of this film 23 is completely covered with Cu or Cr, but it also diffuses into the steel ball 20 to form an intermediate layer, so it has excellent adhesion.

Next, the steel ball 20 coated with Cu or Cr
is used as a substrate, and while the temperature is maintained at 200 to 600° C., the evaporated atoms of Au or Ag are ion-blasted in the same manner as above.

This becomes the deposited film 24 in FIG. 2B, which becomes a hard solid lubricant with a high melting point.

By forming Cu or Cr as an intermediate layer as described above without directly applying Au or Ag ion blating to the steel ball 20, the steel ball 2
This makes it possible to increase the adhesion strength between the lubricant film 24 and the lubricant film 24 and eliminate peeling during use.

That is, Cu and Cr have ionic radii intermediate between the ionic radius of Fe, which is the main component of the steel ball 20, and the ionic radius of Au and Ag, and in particular, Cu is homologous to Au and Ag as seen from the periodic table. And it has the same period (same period) as Fe.

Furthermore, from a macroscopic perspective, Young's modulus and expansion coefficient have values between those of Fe (Ag or Au).

These factors make the adhesion strength high.

The above is the bearing B1 on the target 1 proximal side shown in Figure 1.
Next, the solid lubricant in the bearing B2 at the position away from the target 1, that is, at the anode end, will be described.

FIG. 3 shows the cross sections of the steel ball 25, inner ring 26, and outer ring 27, each surface of which is coated with metal powder such as Pb or Sn, which has a low melting point and hardness, dissolved in alcohol or the like. The membrane is shown.

In addition to the above-mentioned methods, various methods such as vacuum evaporation and sputtering can be used to form this film.

This solid lubricant made of the soft metal film of B2 allows the first
As can be seen in the figure, the rotation noise during high-speed rotation of the anode can be reduced, and the high temperature of target 1 is hardly transmitted to B2 due to the long distance to B2 due to the cooling effect of the cooling oil, so that PB and Sn are No worries about melting or evaporation.

In addition, a large load from the evening target is applied to bearing B1 on the target 1 side, approximately twice the load applied to B1, but as mentioned above, the hard lubricant is able to withstand this sufficiently, and the intermediate Since the layers Cu and Cr act as buffer materials, the rotation noise is also low.

The above is an explanation of the anode bearing of an X-ray tube as an example of this invention. However, this invention is not limited to what is shown in the drawings or the materials and methods described. By using a low melting point soft solid lubricant on the high temperature target side and a low melting point soft solid lubricant on the anode end, we take advantage of the advantages of both.
The key point is to improve the performance of the X-ray tube.

This invention is constructed as described above, so it eliminates the disadvantage of the oil-free lubricant of the anode bearing of the conventional rotating anode X-ray tube, which is an obstacle to improving the performance of the X-ray tube, and reduces the mechanical load. Utilizing new coating technology, we have made the lubricant for the bearings near Targetera 1, which is large and high in temperature, sufficiently resistant to the heat and there is no risk of peeling. By using a conventional solid lubricant, the rotation noise is low and the load on the X-ray tube is increased without the risk of evaporation or peeling of the lubricant, providing a highly reliable X-ray tube that provides sharp images. It was established.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of the anode of a rotating anode X-ray tube according to an embodiment of this invention, Fig. 2 is an explanatory diagram of the ball bearing near the target, Fig. A is a partial cross section of the assembled state, and Fig. B is the steel structure of the rotating anode X-ray tube. FIG. 3 is an explanatory diagram of the formation of a solid lubricant on a ball, and FIG. 3 is an explanatory diagram of a solid lubricant on a ball bearing separated from a target. 1... Rotating anode disk target, 5...
...Above rotating shaft, B1...Ball bearing located close to the disc target, B2...Ball bearing located away from the disc target, 11...Anode fixing base , 20.25... Steel ball, 24... High hardness solid lubricating member coating (Au, Ag, etc.), 23.
...Intermediate layer film (Cu, Cr, etc.) formed between the above coating and the steel ball base, 28...Low hardness solid lubricating member coating (Pb, Sn, etc.).

Claims (1)

[Scope of utility model registration request] In a rotating anode X-ray tube in which the rotation axis of a disk target is rotatably supported on an anode fixed base by a plurality of ball bearings provided in the axial direction, the ball bearings located close to the disk target are made of gold or silver. Melting point 800-1200
The friction surface of the solid lubricating member is treated with a solid lubricating member made of a hard metal at 30°F, and the lower layer of the solid lubricating member is made of copper having an ionic radius intermediate between that of iron, which is a ball bearing material, and that of gold and silver.・A metal film made of chromium or other material is formed, while a ball bearing located at a distance from the disc target is made of lead, tin, etc. with a melting point of 20
A rotating anode X-ray tube characterized in that its friction surface is surface-treated with a soft metal solid lubricating member having a temperature of 0 to 400°C.