JPH05275002A - Manufacture of rotary anode type x-ray tube - Google Patents

Abstract

PURPOSE:To provide the manufacturing method of a rotary anode type X-ray tube provided with ball bearings made of soft metal single layer film with strong adhesive and having the excellent lubricating characteristic. CONSTITUTION:In the manufacture of rotary anode type X-ray tube, the acceleration voltage is heightened and the surface of the steel base material 45 of balls 33, 34 or races 29, 30, 31, 32 of ball bearings 27, 28 is diffused with the solid lubricant by the ion plating method to form a diffusion layer 46 on the surface of the steel base material 45, and continuously, the acceleration voltage is lowered to form a solid lubricant layer 47, and the rotary mechanism is assembled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rotary anode type X-ray tube, and more particularly to a method of coating a surface of a component of a ball bearing which supports the anode target with a solid lubricant.

[0002]

Ball bearings used in rotary anode X-ray tubes are used under severe conditions such as high temperature, high speed rotation, high vacuum, and high load. This ball bearing is composed of a steel inner race, an outer race, and a plurality of balls arranged between the races. In the X-ray tube under the above-mentioned conditions, as a matter of course, ordinary lubricating oil or grease cannot be used. For this reason,
At least one surface of the inner race, the outer race, and the ball is coated with a solid lubricant made of a soft metal such as gold, silver, or lead. As a method for forming a coating film of a solid lubricant, there are an electroplating method, a vacuum vapor deposition method, a sputtering method, an ion plating method and the like, but the ion plating method is superior in that the film has a strong adhesion. The ion plating method is a method of ionizing a vapor deposition material and accelerating and colliding with a bearing component member to which a negative potential is applied in advance to form a film, and the adhesion strength of the film is higher than that of other film forming methods. It has the advantage of being strong. As a method of ionizing the atoms of the vapor deposition substance, glow discharge plasma generated by applying a DC voltage between the substrate and ground in an inert gas atmosphere is used.

The combination of the bearing constituent member and the solid lubricant, which is less likely to diffuse into each other, tends to be preferable in terms of lubricating characteristics. Therefore, for example, when a steel material is used as the base material of the bearing component, silver or lead is suitable as the solid lubricant. However, since iron-based materials and silver or lead are difficult to diffuse into each other, the conventional ion plating method has a drawback that the solid lubricant is easily peeled off and good lubricating characteristics cannot be obtained. ..
Therefore, a technique for interposing a different metal element that easily diffuses between the base material and the solid lubricant is disclosed in, for example, Japanese Utility Model Publication No. 59-691. This method
As shown in FIG. 5, an intermediate intervening layer is first formed on the surface of the steel ball 13 by the ion plating method in the order of the nickel layer 14 and then the copper layer 15, and then the silver thin film 16 as a solid lubricant is formed. To do. Thereby, the adhesion strength is improved. The acceleration voltage in this ion plating is kept constant during film formation, as indicated by reference numeral 17 in FIG.

[0004]

In order to improve the adhesion strength between the base material of the bearing constituent member and the solid lubricant, the dissimilar metal element easily diffusing with them is used as an intermediate layer by the ion plating method. The conventional method of forming has the following drawbacks. (1) It is difficult to control the film thickness of each layer, and reproducibility is poor. (2) If the diffusion layer of the intermediate intervening element and the solid lubricant is projected on the surface, the lubrication characteristics of the bearing deteriorate. (3) Compared with the single layer film, the number of steps is increased and the manufacturing time is lengthened.

The present invention has been made to solve the above-mentioned inconveniences and is a manufacturing method for a rotary anode type X-ray tube provided with a ball bearing having a soft metal monolayer film having a high adhesion strength and good lubricating properties. The purpose is to provide.

[0006]

According to the present invention, the surface of a steel base material constituting at least one of balls and races of a ball bearing is first subjected to an ion plating method to increase its accelerating voltage to form a base material. This is a method of manufacturing a rotary anode type X-ray tube in which a diffusion layer in which a solid lubricant is diffused is formed, and then an accelerating voltage is lowered to form a coating of the solid lubricant layer, and a rotating mechanism is assembled.

[0007]

According to the present invention, the adhesion strength is improved by increasing the ion accelerating voltage at the initial stage of ion plating and driving the solid lubricant in the depth direction of the base material to form a diffusion layer on the surface portion. At the same time, the solid lubricant having a desired film thickness can be easily obtained by lowering the acceleration voltage in the latter half of the ion plating. This makes it possible to efficiently obtain a rotating anode type X-ray tube equipped with a ball bearing having good lubrication characteristics without peeling of the solid lubricant.

[0008]

Embodiments will be described below with reference to the drawings.
The same parts are denoted by the same reference numerals. The embodiment shown in FIGS. 1 to 6 has the following configuration. That is, FIG. 1 is a sectional view of an anode portion of a rotary anode type X-ray tube provided with a solid lubricating ball bearing according to the present invention. Anode target
21 is integrally fixed to a shaft 22, a rotor cylinder 23, and a rotary shaft 24. The substantially cylindrical anode fixed base 25,
It is located between the rotor cylinder 23 and the rotary shaft 24, and its outer end is
26 is an anode support terminal. Two sets of ball bearings 27 and 28 are interposed between the rotary shaft 24 and the anode fixed base 25. Bearings 27 and 28 are inner ring race 29.3
0, outer races 31, 32, and a plurality of balls 33, 34 inserted between them. These inner races, outer races, and balls are made of steel having a high hardness as a base material, and at least one surface of them is coated with a solid lubricant such as silver. The coating method is ball 33
As a typical example, the case of forming on the surface of will be described below.

FIG. 2 schematically shows a DC excitation type ion plating apparatus used in the present invention. First, a large number of steel bearing balls 33 are placed in a rotary barrel 35 provided inside the ion plating apparatus. Next, in the evaporation boat 36, a silver material with a purity of 99.999% or more as an evaporation material.
Insert 37. After evacuating the inside of the vacuum chamber 38 to a vacuum degree of about 10 ^-6 Torr, argon gas is used as an inert gas for 10 ^-2.
Introduce up to about Toll. High voltage DC power supply for rotating barrel 35
Glow discharge is generated by applying a negative DC voltage from 39. In this process, since the silver material 37 does not evaporate, ion bombardment with argon ions is performed,
The surface of the ball 33 is sufficiently cleaned. Then the rotating barrel
35 drive motor 40, gear 41, support rail 42, roller 43,
The rotating shaft 44 rotates and revolves as indicated by the arrow. Then, the accelerating voltage is raised to 10 kV and the temperature of the vapor deposition boat 36 is raised to about 1200 ° C. or higher to evaporate the silver material 37. This initial stage is represented by symbol P1 in FIG. After about 5 minutes, the accelerating voltage is lowered to 3 kV, and ion plating is performed for about 10 minutes. This step is represented by the symbol P2 in FIG.

By the above operation, as shown in FIG.
On the surface of the steel base material 45 of the ball 33, a diffusion layer 46 in which silver ions of a solid lubricant are implanted and diffused is formed thinly. Then, a silver lubricating film 47 having a thickness of about 0.1 μm is coated on the diffusion layer 46. The boundaries between the layers are not clear and are almost continuous, and therefore peeling is unlikely to occur. By the way, it is generally known that, when a solid surface is irradiated with metal ions, the following three phenomena occur depending on the magnitude of the kinetic energy E thereof. (a) Deposition phenomenon (E ≦ 500 eV) (b) Sputtering phenomenon (E ≧ 50 eV) (c) Ion implantation phenomenon (E ≧ 500 eV)

In the above operation of the present invention, in the initial film formation (P1
) Is 2 to 3 times higher than the accelerating voltage during the formation of the lubricating film 47 (P2), and the silver ion is moved in the depth direction of the base material 45 by the phenomenon of (c) above. Implantation, diffusion layer 46
Is formed. Then, subsequently, the acceleration voltage is lowered, and the sufficiently thick silver lubricating film 47 is attached by utilizing the phenomenon (a). In the ion plating apparatus used in the present invention, the phenomenon (c) above could be realized at an accelerating voltage of 8 kV or more. However, if vapor deposition is continued while the accelerating voltage remains high, the reverse sputtering phenomenon causes the silver deposition rate to decrease, and it takes an undesirably long time to obtain a desired film thickness. Therefore, the accelerating voltage is lowered from the middle, and the above (a)
By this phenomenon, a silver film is rapidly deposited to obtain a lubricating film 47 having a desired film thickness. In the ion plating device used in the present invention, the lubricating film 47 could be realized with an acceleration voltage in the range of 2 to 4 kV. In addition, as the material of the solid lubricant,
Not only silver, but also known solid lubricants such as gold, lead and other rolling bearings for high temperature and high vacuum can be used.

[0012]

As described above, according to the present invention,
By forming the diffusion layer on the surface of the base material of the ball bearing component, the adhesion strength is improved and a solid lubricating film having a desired thickness can be easily obtained. As a result, there is no risk of the solid lubricating film peeling off, and it is possible to efficiently manufacture a rotary anode type X-ray tube provided with a bearing having good lubricating characteristics.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotary anode type X-ray tube showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of an ion plating device used in the present invention.

FIG. 3 is a half sectional view of a ball manufactured according to the present invention.

FIG. 4 is a graph showing the manufacturing method of the present invention.

FIG. 5 is a half sectional view of a conventional ball.

FIG. 6 is a graph showing a conventional manufacturing method.

[Explanation of symbols]

 21… Anode target, 27,28… Ball bearing, 29,30… Inner ring race, 31,32… Outer ring race, 33,34… Ball, 45… Base material, 46… Diffusion layer, 47… Solid lubricating film. P1 ... Acceleration voltage when forming the diffusion layer, P2 ... Acceleration voltage when forming the solid lubricating film.

Claims (1)

[Claims] 1. A method of manufacturing a rotary anode X-ray tube in which at least one of a ball and a race has a ball bearing coated with a solid lubricant so as to rotatably support an anode target. On the surface of the steel base material that composes the ball or race, the acceleration voltage is first increased by the ion plating method to form a diffusion layer in which the solid lubricant is diffused in the base material, and then the acceleration voltage is applied. A method of manufacturing a rotating anode type X-ray tube, which comprises lowering and coating a solid lubricant layer to assemble a rotating mechanism.