JPH10241614A - Vacuum bearing, manufacture thereof and rotary anode type x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum bearing that can maintain a good lubricating characteristics without deteriorating a rotating characteristics by providing a surface phase, formed of Ni, Cr, Pt or an alloy of these elements, between a solid lubricating layer and a bearing part with the solid lubricating layer formed, thereby shutting out gas, penetrating the solid lubricating layer by the surface phase to prevent oxidation of the bearing part. SOLUTION: Solid lubricating layers formed of lead, silver, or the like are formed at the mutual contact parts of a plurality of bearing parts, constituting a vacuum bearing. At this time, a metal surface phase 31, formed on at least one material from among Ni, Cr, Pt, and an alloy of these element is formed between the bearing part, such as a ball R3 and the solid lubricating layer 32 provided thereon. If is preferable that this surface phase 31 be formed to a film thickness of about 0.05-0.1μm by an ion planting method, while the solid lubricating layer 32 be formed to a film thickness of about 0.3-0.5μm by an ion-implantation using different material from the surface phase 31. A shift preventive film formed of Ni, Ti, Sn, Pt, or the like can also be provided on the solid lubricating layer which is provided on the bearing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum bearing used in a vacuum or the like, a method for manufacturing the same, and a rotary anode type X-ray tube using the vacuum bearing.

[0002]

2. Description of the Related Art A rotating anode X-ray tube is an electron tube that irradiates a rotating anode target with an electron beam and generates X-rays from the rotating anode target, and is used for medical X-ray diagnostic equipment and the like. Have been. In the rotating anode X-ray tube having such a structure, a vacuum bearing is used between a rotating mechanism that rotates integrally with the anode target and a fixed mechanism that supports the rotating mechanism.

[0003] The inside of a rotating anode type X-ray tube is kept in a high vacuum state of 10 ^-3 Pa or more, and the temperature of the anode rises during use. For this reason, the temperature of the bearing portion disposed between the rotation mechanism and the fixing mechanism also becomes high at 300 ° C. to 500 ° C.
Under such conditions of high vacuum and high temperature, grease or the like generally used as a lubricant for the bearing cannot be used. Therefore, a solid lubricant mainly containing a soft metal such as lead or silver is used.

In the case of using a solid lubricant, a method of forming a layer of the solid lubricant on the surface of a vacuum bearing component by plating has been widely adopted. However, recently, an ion plating method has been used because a solid lubricant having excellent uniformity can be obtained.

[0005]

A soft metal such as lead or silver used as a solid lubricant has good properties as a lubricant even in a high vacuum state or a high temperature state. However, when a solid lubricant is adhered to a vacuum bearing component using an ion plating method, it is usually formed as a solid lubricant layer in a vacuum of about 1 to 10 ⁻² Pa. Therefore, the solid lubricating layer tends to be a porous thin film. As a result, the solid lubricating layer easily adsorbs gas and easily permeates gas.

At this time, when lead is used as the solid lubricant, the oxidation of lead does not cause much problem because lead oxide has lubricity. However, when the solid lubrication layer allows gas to permeate,
The race surface and ball surface of the vacuum bearing may be oxidized. When the surface of the vacuum bearing oxidizes, a layer of iron oxide is formed between the solid lubrication layer and the bearing component. The iron oxide layer is hard,
Also, since it is brittle, it has a bad influence on lubrication characteristics. For example,
During use, the iron oxide layer may peel off, impairing rotational characteristics.

When lead or silver is used as a solid lubricant, the remaining oxidizing gas and lead or silver react with each other to form an oxide, thereby rotating the rotating anode X-ray tube. Characteristics may be impaired.

Further, a part of the solid lubricant formed on a bearing component such as a ball may peel off, and the peeled solid lubricant may move and adhere to another race surface. When the solid lubricant thus peeled is transferred to another race surface, the lubrication state changes and the rotational characteristics of the rotary anode X-ray tube are impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks and to provide a vacuum bearing which does not impair the rotational characteristics, a method for manufacturing the same, and a rotary anode type X-ray tube.

[0010]

According to the present invention, there is provided a vacuum bearing comprising a plurality of bearing parts, wherein at least one of the bearing parts in contact with each other has a solid lubrication layer formed thereon. An interface layer of Ni, Cr, Pt and at least one material selected from alloys of Ni, Cr, and Pt is provided between the bearing component and the solid lubricating layer. .

Further, the method for producing a vacuum bearing according to the present invention comprises:
Ni, C is formed on at least one of the contacting parts of the vacuum bearing composed of a plurality of bearing parts.
forming an interface layer using at least one material selected from r, Pt, and alloys of Ni, Cr, and Pt; and a solid lubricant of a material different from the interface layer on the interface layer. And a step of forming a solid lubricating layer by using

Further, the present invention is characterized in that the interface layer is formed by an ion plating method, and the solid lubricating layer is formed by an ion implantation method.

The rotating anode type X-ray tube according to the present invention comprises a rotating mechanism that rotates integrally with an anode target that generates X-rays, a fixing mechanism that supports the rotating mechanism, the rotating mechanism and the fixing mechanism. And the vacuum bearing according to claim 1 which is disposed between them.

The present invention also relates to a vacuum bearing comprising a plurality of bearing parts, wherein at least one of the bearing parts in contact with each other has a solid lubrication layer formed thereon, wherein Ni, Ti , Sn, Pt, and N
It is characterized in that a transfer prevention film of at least one material selected from the compounds of i, Ti, Sn and Pt is provided.

Further, the method for manufacturing a vacuum bearing according to the present invention comprises:
Forming a solid lubricating layer on at least one of the bearing parts of the vacuum bearing composed of a plurality of bearing parts using a solid lubricant on at least one of the contacting parts; Ni, Ti, Sn, Pt and Ni, Ti, S
forming a transfer prevention film using at least one material selected from the compounds of n and Pt.

The rotating anode X-ray tube according to the present invention comprises a rotating mechanism that rotates integrally with an anode target that generates X-rays, a fixing mechanism that supports the rotating mechanism, the rotating mechanism and the fixing mechanism. The vacuum bearing according to claim 5, which is disposed between them.

According to the above configuration, an interface layer of a metal material different from the material of the solid lubrication layer is provided between the bearing component and the solid lubrication layer formed on the bearing component. In this case, even if gas permeates the solid lubrication layer, it can be blocked by the interface layer, oxidation of the race surface and ball surface of the vacuum bearing can be prevented, and good lubrication characteristics can be maintained without impairing the rotation characteristics.

Further, on the solid lubricating layer formed on the bearing component, a transfer preventing film of a metal material different from the material of the solid lubricating layer is provided. In this case, deterioration of the solid lubricant can be prevented by the transfer prevention film, and transfer of the solid lubricant can be prevented. As a result, good lubrication characteristics can be maintained for a long period of time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows the entire structure of a rotating anode type X-ray tube, in which a part of the upper half of a tube axis M is shown in cross section.

Reference numeral 11 denotes a vacuum envelope constituting a rotary anode type X-ray tube. A cathode 13 for generating an electron beam 12 is disposed at one end of the vacuum envelope 11, and at the other end of the vacuum envelope 11. An anode 14 is arranged. The anode 14 includes an anode target 15 located near the cathode 13 and an anode target 1.
5 is constituted by a rotation device 16 for rotating the rotating member 5 and the like.
The rotating device 16 includes a rotating mechanism that rotates integrally with the anode target 15 and a fixed mechanism that supports the rotating mechanism. The rotating mechanism includes a rotating shaft 16a serving as a rotating shaft.
And a rotor 16b surrounding the rotating shaft 16a. The fixing mechanism includes a fixed body 16c located in a space inside the rotor 16b. And
A vacuum bearing 16d is arranged between the rotating shaft 16a of the rotating mechanism and the fixed body 16c of the fixing mechanism. Bearing for vacuum 1
6d is, for example, an outer ring R1, an inner ring R2, and an outer ring R
1 and a ball R3 sandwiched between the race surfaces of the inner ring R2. In addition, the envelope 11 close to the rotation mechanism 16
A stator coil 17 for applying a rotating force to the rotating mechanism is disposed outside the rotating shaft.

In the above configuration, when a current flows through the stator coil 17, the stator coil 17 generates a rotating magnetic field, and the rotating shaft 16a and the rotor 16b rotate. As a result, the anode target 15 rotates. In this state, the electron beam 12 is irradiated from the cathode 13 to the anode target 15, and the anode target 15 generates X-rays 18.

Here, the vacuum bearing 16d used in the rotary anode type X-ray tube having the above-described configuration will be described with reference to FIG. In FIG. 2, portions corresponding to FIG. 1 are denoted by the same reference numerals. The vacuum bearing 16d is provided with the outer ring R1 and the inner ring R
2, and each bearing component such as a ball R3 sandwiched between the race surfaces of the outer ring R1 and the inner ring R2. In the figure, a part of the outer ring R1 is shown in cross section. Each of the bearing components R1 to R3 is made of, for example, high-speed tool steel and has an outer ring R1.
For example, a solid lubricating layer is formed on one of the bearing component surfaces that are in contact with each other such as the race surface of the inner ring R2 or the surface of the ball R3.

Next, a case where a solid lubricating layer is formed on, for example, the surface of the ball R3 of the bearing component will be described with reference to FIG. Reference numeral R3 denotes a ball. An interface layer 31 is formed on the surface of the ball R3 using a metal material, and a solid lubricating layer 32 is formed on the interface layer 31. The interface layer 31 is made of, for example, nickel (Ni) and has a thickness of 0.005 to 0.1 μm by an ion plating method. The solid lubricating layer 32 is made of, for example, lead (Pb). The solid lubricating layer 32 is formed to have a thickness in the range of 0.3 to 0.5 μm by an ion implantation method in which the ion acceleration voltage is higher than in the case of the ion plating method.

The material of the interface layer 31 is not limited to Ni,
Chromium (Cr), platinum (Pt), Ni, Cr,
An alloy of each of Pt can also be used.

According to the above configuration, since the interface layer is formed between the solid lubricating layer 32 and the bearing component such as a ball, oxidation of the bearing component can be prevented, and good rotational characteristics can be maintained.

Next, another example of forming a solid lubricating layer on the surface of the ball R3 as a bearing component will be described with reference to FIG. Reference numeral R3 denotes a ball, on which a solid lubrication layer 41 is formed and on the solid lubricant layer 41, a transfer prevention film 42 is formed. Silver (A
g) is used, and the film thickness is formed to be 0.1 μm.
Further, Ni is used for the transfer prevention film 42 and the film thickness is set to 0.1.
It is formed to 1 μm. In this case, the solid lubrication layer 41 and the transfer prevention film 42 are formed by an ion plating method or a sputtering method, respectively.

As the metal material for forming the transfer prevention film 42, in addition to Ni, Ti, tin (Sn), Pt, or a compound of each of Ni, Ti, Sn, and Pt can be used.

According to the above configuration, since the transfer preventing film 42 is provided on the solid lubricating layer 41, deterioration and transfer of the solid lubricant can be prevented, and good lubricating properties can be maintained for a long time.

Further, in the above-described embodiment, the solid lubricant layer, the interface layer, and the transfer prevention film are formed on the bearing component, for example, the ball R3. In the case of the present invention, it can be formed on the race surface of the outer ring R1 or the inner ring R2 of another bearing component. Although the case where the solid lubricating layer 32 is made of lead has been described, a soft metal such as Ag, gold (Au), or MoS2,
WS2 or the like can also be used.

[0030]

According to the present invention, it is possible to realize a vacuum bearing, a method of manufacturing the same, and a rotating anode type X-ray tube in which rotation characteristics are not impaired.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a part of a rotary anode X-ray tube for describing an embodiment of the present invention.

FIG. 2 is a schematic structural view for explaining an embodiment of the present invention, in which a part of a vacuum bearing is shown in cross section.

FIG. 3 is a view for explaining an embodiment of the present invention, and is a cross-sectional view of a ball as a bearing component.

FIG. 4 is a view for explaining another embodiment of the present invention, and is a cross-sectional view of a ball as a bearing component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Vacuum envelope 12 ... Electron beam 13 ... Cathode 14 ... Anode 15 ... Anode target 16 ... Rotating mechanism 16a ... Rotating shaft 16b ... Rotor 16c ... Fixed body 16d ... Vacuum bearing 17 ... Stator 18 ... X-ray 31 ... Interface Layers 32, 41: Solid lubrication layer 42: Transfer prevention film R1: Outer ring R2: Inner ring R3: Ball

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hisayuki Tamura 1385-1 Shimoishigami, Otawara-shi, Tochigi Prefecture Inside the Toshiba Nasu Electron Tube Factory (72) Inventor Hidemichi Ozaki 1385-1 Shimoishigami, Otawara-shi, Tochigi Company Toshiba Nasu Electron Tube Factory

Claims (7)

[Claims] 1. A vacuum bearing comprising a plurality of bearing parts and having a solid lubrication layer formed on at least one of the bearing parts in contact with each other, wherein the solid lubrication layer and the solid lubrication layer are formed. Ni, between the bearing parts
A vacuum bearing provided with an interface layer of Cr, Pt, and at least one material selected from alloys of Ni, Cr, and Pt. 2. A vacuum bearing composed of a plurality of bearing parts, wherein at least one of the bearing parts in contact with each other is selected from Ni, Cr, Pt and alloys of Ni, Cr, and Pt. Manufacturing a vacuum bearing comprising: a step of forming an interface layer using at least one material; and a step of forming a solid lubricant layer on the interface layer using a solid lubricant of a different material from the interface layer. Method. 3. The method according to claim 2, wherein the interface layer is formed by an ion plating method, and the solid lubricant layer is formed by an ion implantation method. 4. The rotating mechanism according to claim 1, wherein the rotating mechanism rotates integrally with the anode target that generates X-rays, a fixing mechanism supporting the rotating mechanism, and the rotating mechanism is disposed between the rotating mechanism and the fixing mechanism. A rotary anode type X-ray tube comprising a vacuum bearing. 5. A vacuum bearing comprising a plurality of bearing parts, wherein at least one of the bearing parts in contact with each other has a solid lubrication layer formed thereon, wherein the solid lubrication layer has
Ni, Ti, Sn, Pt, and Ni, Ti, Sn,
A vacuum bearing comprising a transfer prevention film of at least one material selected from each compound of Pt. 6. A step of forming a solid lubricating layer using a solid lubricant on at least one of the bearing parts of a vacuum bearing composed of a plurality of bearing parts, the parts being in contact with each other; , Ni, Ti, Sn, Pt, and
Forming a transfer prevention film using at least one material selected from compounds of Ni, Ti, Sn, and Pt. 7. The rotating mechanism according to claim 5, wherein the rotating mechanism rotates integrally with the anode target that generates X-rays, a fixing mechanism supporting the rotating mechanism, and the rotating mechanism is disposed between the rotating mechanism and the fixing mechanism. A rotating anode type X-ray tube equipped with a vacuum bearing.