JPH06314549A - Rotation anode x-ray tube - Google Patents

Abstract

PURPOSE:To provide a rotation anode X-ray tube in which a solid lubricant is restrained from being transferred to inner and outer rings so that it has a good lubrication characteristic. CONSTITUTION:A rotation anode X-ray tube has a rotor to which an anode target 3 is secured, a fixed body coaxially fitted into the rotor, a pair of ball bearings 8, 9 each comprising a ball 12, an inner 13 and outer 14 ring all of which are disposed between the fixed body and the rotor, and a solid lubricant covering the ball. A coat made from a material with which the solid lubricant is hard to form a solid solution is attached to the area of contact between the inner or outer ring and the ball.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary anode type X-ray tube, and more particularly to improvement of its rotating mechanism.

[0002]

2. Description of the Related Art Generally, an X-ray tube is used for medical purposes as an X-ray diagnosis, for example, but a rotary anode type X-ray tube is used for a gastric examination. In this rotary anode type X-ray tube, an eccentric cathode and a substantially umbrella-shaped anode target are disposed opposite to each other in a vacuum envelope, and the anode target is supported by a rotating mechanism and can rotate. ing.
Furthermore, outside the vacuum envelope, there is a stage corresponding to the rotating mechanism.
Is installed to drive the rotating mechanism.

This rotating mechanism has a rotating cylinder to which an anode target is fixed, a rotating shaft coaxially fixed to the inside of the rotating cylinder, and a coaxial fitting between the rotating shaft and the rotating cylinder. It has a bottomed cylindrical anode fixing base and a pair of ball bearings, which are interposed between the anode fixing base and the rotating shaft, and which are composed of a ball, an inner ring and an outer ring.

By the way, the ball bearing is used under severe conditions such as high temperature, high speed rotation, high vacuum and high load. Under such conditions, as a matter of course, ordinary lubricating oil, grease, etc. cannot be used. Therefore, in general, Au (gold) or Ag is attached to the surface of the ball or the race surface of the inner ring or the outer ring or the race surface of either the inner ring or the outer ring.
A soft metal such as (silver) or Pb (lead) is coated as a solid lubricant. As a coating method of the 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 often used because of the strong adhesion of the coated film. And, the material of the ball, the inner ring and the outer ring and the solid lubricant are more preferable in terms of the lubrication characteristics as the combination in which mutual diffusion is difficult.
For example, when a steel-based material is used as the material for the balls, the inner ring, and the outer ring, Ag or Pb is generally used as the solid lubricant. However, as described above, the rotary anode type X-ray tube is used under severe conditions such as high temperature, high speed rotation, high vacuum, and high load load, and therefore, for example, a ball bearing ball made of a steel material. Even when only the solid lubricant was coated, the transfer of the solid lubricant to the race surfaces of the inner and outer rings was unavoidable.

[0005]

When a solid lubricant composed of a soft metal is used by coating only the ball, it is considered that the solid lubricant is roughly classified into the following four states with time. . (1) Soft metal is not transferred to the race surface, and most of the soft metal is present on the ball surface in the initial state. (2) Thin on the race surface and the ball surface Middle state where uniform soft metal is present, (3) Late state where base metal is locally exposed due to roughened soft metal present on race surface and ball surface, (4) The state where (3) above progresses further and lubrication is cut off, and the base metal is damaged.

From the viewpoint of lubrication characteristics, it is desirable that the above conditions (1) and (2) continue stably for a long time. However, as described above, under the severe conditions such as the rotary anode type X-ray tube. Used box
It is difficult for the ru-bearing to maintain the state of (1) and (2) stably for a long time, and it is a major factor that influences the rotation characteristics and the life of the rotary anode type X-ray tube.

The present invention solves the problem of deterioration of lubrication characteristics due to the transfer of the solid lubricant coated on the balls to the race surfaces of the inner ring and the outer ring. It is an object of the present invention to provide a rotating anode type X-ray tube which suppresses the transfer to the outer ring and has good lubricating characteristics.

[0008]

According to the present invention, there are provided a rotating body having an anode target fixed thereto, a fixed body coaxially fitted to the rotating body, and the fixed body and the rotating body. A pair of ball bearings formed of a ball, an inner ring, and an outer ring, and a solid lubricant coated on the ball,
Further, it is a rotary anode type X-ray tube in which a coating film made of a material in which a solid lubricant is difficult to form a solid solution is attached to a region of the inner ring or the outer ring which contacts the ball.

[0009]

According to the present invention, since the solid lubricant is suppressed from transferring to the inner ring and the outer ring, it becomes possible to maintain the state in which the solid lubricant is present on the ball surface for a very long time. Improves ball bearing rotation characteristics and life.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. The rotating mechanism of the rotary anode type X-ray tube according to the present invention is constructed as shown in FIGS. 1 and 2, FIG. 2 shows the whole, and FIG. 1 shows a ball bearing in an enlarged manner. That is, reference numeral 1 in FIG. 2 is a rotary cylinder, and a support column 2 is coaxially and integrally provided on the rotary cylinder 1 by brazing, and an anode target 3 and a screw 4 are provided on the support column 2. It is fixed by a stopper. A rotary shaft 5 is coaxially fixed to the inside of the rotary cylinder 1. in this case,
A disc 5a is integrally formed at one end of the rotary shaft 5,
This disc 5a is fixed to the inner surface of the lid of the rotary cylinder 1 by the mounting screw 6. The rotating cylinder 1, the supporting column 2 and the rotating shaft 5 constitute a rotating body.

Further, between the rotary shaft 5 and the rotary cylinder 1, a bottomed cylindrical anode fixing base 7 which is a fixed body is coaxially fitted, and the anode fixing base 7 is a rotary anode type X-ray tube. Is fixed to a vacuum envelope (not shown). This anode fixed base 7
A pair of ball bearings 8 and 9 are provided between the rotary shaft 5 and the rotary shaft 5.
The ball bearings 8 and 9 are fixed at a predetermined interval by a cylindrical spacer 10 and fixed by a fixing ring 11.

The ball bearings 8 and 9 are composed of a ball 12, an inner ring 13 and an outer ring 14, and the ball 12 is made of Au (gold), Ag (silver) or Pb (lead). Soft metal is coated as a solid lubricant. Further, in this embodiment, as shown in FIG. 1, in the regions of the inner ring 13 and the outer ring 14 in contact with the balls 12, the coating 15 made of a material in which the above solid lubricant is hard to form a solid solution, for example, TiC, has a thickness of 0. 1 to
0.2 μm is attached.

The coating 15 is formed by an ion plating method, and the direct current excitation type ion plating shown in FIG. 3 is used.
Use a touching device. In the drawing, reference numeral 16 is a vacuum envelope, 17 is a holding jig, 18 is a crucible, 19 is a Ti material, 20 is an electron gun, 21 is a drive motor, 22 is a high voltage DC power supply, and 23 is an electron gun. Power supply, 24 is ethane gas inlet,
Reference numeral 25 is an inert gas introduction port, and 26 is an exhaust port. In order to form the coating 15 using this apparatus, first, the holding jig 17 is used to form the inner ring 13 or the outer ring 14 of the ball bearings 8 and 9.
A plurality of are held and the crucible 18 is filled with the Ti material 19. Then, after evacuating the inside of the vacuum envelope 16 to about 10 ⁻⁶ Torr, an argon gas of 10 ^{−3 is used} as an inert gas.
After introducing about Torr and applying a negative DC voltage to the holding jig 17, plasma is generated by glow discharge, and the holding jig 17 is ion bombarded. In this step, the holding jig 1 that was not completely removed by solvent washing
The removal of impurities on the surface 7 and the heating of the holding jig 17 are performed at the same time, which contributes to improving the adhesion of the coating 15.

In this ion bombardment process, the applied voltage (-3 KV) is continued for about 10 minutes. Next, the holding jig 17 is rotated about 20 revolutions per minute to drive the electron gun power source 22 to heat the Ti material 19. At this time, by increasing the acceleration voltage of the electron gun 20 to about 5 KV,
The Ti material 19 reaches its melting point and evaporates. At the same time, about 100 cm ³ of ethane is introduced into the vacuum envelope 16 per minute. Since this ethane decomposes in plasma to form carbon, it combines with evaporated Ti to form TiC.

By continuing the above-mentioned operation for about 10 minutes, as shown in FIG. 1, the inner ring 13 or the outer ring 14 or both of the race surfaces are coated with Ti having a thickness of 0.1 to 0.2 μm.
A coating film 15 made of C is formed.

FIG. 4 shows a friction torque characteristic 27 in the rotary anode type X-ray tube of the present invention and a friction torque characteristic 28 in the conventional rotary anode type X-ray tube. In the case of the conventional structure, the fluctuation of the friction torque is large, and the life is reached at about 1 × 10 ⁸ rev. However, in the case of the present invention, the friction torque is stable at a relatively low level from the initial stage and is 1.5 × 10 8. ⁸
Even when it exceeded rev, it did not reach the end of its life and was in a good lubricating state.

[0017]

According to the present invention, since the coating made of a material in which the solid lubricant is difficult to form a solid solution is adhered to the region of the ball bearing which contacts the ball of the inner ring or the outer ring, the solid lubricant is The transfer to the inner or outer ring is suppressed. As a result, the state in which the solid lubricant is present on the surface of the ball can be maintained for a very long time, and the rolling characteristics and life of the ball bearing are improved.

[Brief description of drawings]

FIG. 1 is a partially sectional perspective view showing an enlarged main part of a rotating mechanism of a rotary anode type X-ray tube according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an entire rotating mechanism of a rotary anode type X-ray tube according to an embodiment of the present invention.

FIG. 3 is a schematic vertical sectional view showing a DC excitation type ion plating apparatus used for manufacturing the rotating anode type X-ray tube of the present invention.

FIG. 4 is a characteristic curve diagram showing a relationship between cumulative rotational speed and friction torque in a conventional rotary anode type X-ray tube of the present invention.

[Explanation of symbols]

1 ... Revolving cylinder, 3 ... Anode target, 5 ... Rotating shaft, 7 ...
Anode fixing base, 8, 9 ... Ball bearing, 12 ... Ball
Le, 13 ... Inner ring, 14 ... Outer ring, 15 ... Coating.

Claims (1)

[Claims] 1. A rotating body having an anode target fixed thereto,
A fixed body which is coaxially fitted to the rotating body, and a ball, an inner ring, which is arranged between the fixed body and the rotating body,
In a rotary anode X-ray tube comprising a pair of ball bearings composed of outer rings and a solid lubricant coated on the balls, the solid material is provided in a region in contact with the balls of the inner ring or the outer ring. A rotating anode type X-ray tube having a coating film made of a material in which a lubricant hardly dissolves.