JPH0613007A - Rotating anodic x-ray tube - Google Patents

Abstract

PURPOSE:To maintain stable bearing operation by preventing the damage of a bearing by forming a spiral groove on a dynamic pressure sliding bearing. CONSTITUTION:Radial channels 25, one end of which is connected to a lubricant storage chamber 23, and the other end of which is opened to the outer peripheral surface of a fixed body 15, is formed at five points symmetrically around an axis, at an interval of 90 deg.. The radial channel 25 of the center part in the axial direction, is opened to a small diameter part 24. Remaining four channels 25 are opened in the vicinity of the outer end part in the region of spiral grooves 19a, 19b of herringbone pattern of radial sliding bearings 20a, 20b. Even when a liquid metal lubricant supplied to the spiral grooves and a bearing gap G is relatively reduced during high speed rotation of a rotor 12 as indicated by an arrow P, the lubricants filled in the chamber 23 and the channels 25 are promptly supplied since the channels 25 extending from the chamber 23 are opened. The lubricant is surely distributed, and damage of bearing surface is prevented, while stable bearing operation of a dynamic pressure sliding bearing can thus be maintained.

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 a bearing structure.

[0002]

2. Description of the Related Art As is well known, a rotary anode type X-ray tube supports a disk-shaped anode target with a rotating body and a fixed body having bearings between them, and energizes an electromagnetic coil arranged outside the vacuum container. While rotating at a high speed, an electron beam is emitted from the cathode and hits the anode target to emit X-rays. The bearing is a rolling bearing such as a ball bearing, or a metal that forms a spiral groove on the bearing surface and becomes liquid during operation, such as a gallium (Ga) or gallium-indium-tin (Ga-In-Sn) alloy. It is composed of a dynamic pressure type sliding bearing using a lubricant. Examples of the latter slide bearing are disclosed, for example, in Japanese Examined Patent Publication No. 60-21463, Japanese Patent Laid-Open No. 60-97536,
JP-A-60-117531, JP-A-62-287555, JP-A-2-22
It is disclosed in each publication such as 7947 or JP-A-2-227948.

[0003]

In the rotary anode type X-ray tube provided with the dynamic pressure type slide bearing using such a liquid metal lubricant, the herringbone pattern spiral groove is adopted, and the lubricant is patterned during the rotating operation. The dynamic pressure is generated by being scraped up from the peripheral part of the to the part that is folded back into a dogleg in the central part. The bearing surface is kept in a non-contact state at intervals of, for example, about 20 μm during the rotating operation. However, when the rotation is stopped, at least a part of the bearing surface contacts due to the weight of the rotating body. If the lubricant is present as a thin film on this contact surface, the bearing surfaces will not be rubbed against each other and scratches will not occur even when the next rotation is started. However, in the bearing surface in the region where the lubricant is diluted during operation, there may be a state where the lubricant does not exist between the contacting bearing surfaces when the rotation is stopped. If the lubricant is not present between the bearing surfaces, at the time of the next rotation start, rubbing occurs, and the bearing surfaces are likely to be scratched or seized.

The present invention eliminates the above-mentioned inconveniences, and can reliably supply the liquid metal lubricant to the sliding bearings at the time of starting the rotation and at the time of continuous rotation, so that the bearings are not damaged and the dynamic pressure type sliding is stable. An object of the present invention is to provide a rotating anode type X-ray tube capable of maintaining the bearing operation.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a lubricant passage or a lubricant accommodating recess which opens in a region of a dynamic pressure slide bearing where a spiral groove is formed is formed, and a lubricant is retained in the slide bearing region. Rotating anode type X configured to surely spread
It is a line tube.

[0006]

According to the present invention, the liquid metal lubricant is surely spread over the bearing surface of the slide bearing during rotation start and continuous rotation, damage to the bearing surface is prevented in advance, and a stable dynamic pressure slide bearing is provided. Operation is maintained.

[0007]

Embodiments will be described below with reference to the drawings.
The same parts are represented by the same symbols. The embodiment shown in FIGS. 1 to 4 has the following configuration. That is, a disk-shaped anode target 11 made of heavy metal is integrally fixed to a rotating shaft 13 protruding from one end of a bottomed cylindrical rotating body 12 by a nut 14. The rotor 12 is coaxially fitted and fixed to the outer periphery of a double rotor cylinder including a ferromagnetic cylinder 12a such as iron and a good conductor cylinder 12b such as copper.
A cylindrical fixed body 15 is inserted inside the rotating body 12. The lower end of the fixed body 15 in the figure, that is, the rotary body opening 12
A fixed body small diameter portion 15a having a reduced outer diameter is formed in the vicinity of c. A ring-shaped opening closing body 16 that closely surrounds the fixed body small diameter portion 15a and substantially closes the opening is fixed to the rotating body opening 12c by a plurality of bolts 16a. . An iron alloy anode support 17 for mechanically supporting the rotating body 12 and the fixed body 15 is fixed to the small fixed body diameter portion 15a by brazing, and this is an auxiliary ring 17a.
a vacuum container 18 made of glass via a and the seal ring 18b
It is airtightly joined to.

A dynamic pressure type spiral groove slide bearing as shown in each of the above-mentioned publications is formed at the fitting portion of the cylindrical rotating body 12 and the fixed body 15. That is, on the outer peripheral wall of the fixed body 15, spiral grooves 19a and 19b of a herringbone pattern are formed at predetermined intervals in the axial direction, and two radial slide bearings 20a and 20b are formed. Also, the fixed body 15
On the upper end wall of the figure, that is, on the surface perpendicular to the rotation axis, there is formed a spiral groove 21a having a circular herringbone pattern shown in FIG. 3, and one thrust slide bearing 22a is constituted. Similarly, on the upper surface 16c of the opening blocker 16, a spiral groove having a circular herringbone pattern shown in FIG.
21b is formed, and the other thrust slide bearing 22b is formed. Both the bearing surfaces of the rotating body and the fixed body face each other with a bearing gap G of about 20 μm during the rotating operation.

Therefore, the fixed body 15 is provided with a lubricant accommodating chamber 23 whose central portion is a hole cut out along the axial direction. The illustrated upper end opening 23a of the lubricant containing chamber 23
Is located in the center of the inside of the circular spiral groove 21a at the top of the drawing and communicates with the bearing gap G of the thrust bearing 22a. The lower end 23b in the figure of the lubricant accommodating chamber 23 is extended to a position near the lower thrust spiral groove slide bearing 22b and terminates. Further, the fixed body 15 has a small diameter portion 24 formed by cutting the outer peripheral wall of the intermediate portion thereof.
The radial passages 25, 25 ... Each of which has one end connected to the lubricant accommodating chamber 23 and the other end opening located on the outer peripheral surface of the fixed body 15 are axially symmetric at intervals of 90 degrees at five axial positions. Is formed in. The radial passage 25 at the center in the axial direction is
It is open to. The remaining four radial passages 25,25 ...
Respectively open in the region of the spiral grooves 19a, 19b of the herringbone pattern of each radial plain bearing 20a, 20b, particularly preferably in the vicinity of the outer end portion, that is, the portion near the upper and lower ends in the drawing. These opening positions are regions where the liquid metal lubricant supplied to the spiral groove and the bearing gap becomes relatively small when the rotating body 12 rotates at a high speed as indicated by an arrow P.
That is, the lubricant in the spiral groove and the bearing gap G in this portion is scraped up in the axial center of the spiral groove of the herringbone pattern, so that the lubricant is diluted in the outer end region. However, since the radial passages 25, 25 ... That extend from the lubricant accommodating chamber 23 are opened in this portion, the lubricant filled in the lubricant accommodating chamber and the radial passage is promptly bearing during both rotation start and continuous rotation. Supplied to the area. Therefore, the lubricant is always interposed between the bearing surfaces. Further, since the lubricant is supplied from the lubricant containing chamber 23 through the radial passage 25 to the circumferential space S1 formed by the small diameter portion 24, the lubricant is also spread to the bearing surface having no spiral groove. Furthermore, the thrust bearing is also supplied with the lubricant from the opening of the lubricant containing chamber and the adjacent radial passage 25. In this way, the lubricant is reliably supplied to all the bearing surfaces. In this embodiment, the radial passages 25, 25 ... Open into the spiral grooves 19a, 19b. As a result, the lubricant supplied from each radial passage 25 enters the spiral grooves and spreads also to the bearing surface between the spiral grooves, so that a smooth rotation start is guaranteed.

The opening closing body 16 and the small fixed body diameter portion 15a
A circular cavity 26 formed by cutting a part of the small-diameter portion of the fixed body into a circular shape is provided between and. The cylindrical portion 16b of the closing body forms a slight gap Q with the inner small diameter portion 15a of the fixed body, and has a screw pump groove 27 on the inner peripheral surface. The screw pump groove 27 and the gap Q form a lubricant leakage suppressing means. The circumferential cavity 26 has a size sufficiently larger than the size of the gap Q in the radial direction.
As described above, in the spiral groove of each bearing 20a, 20b, 22a, 22b, the bearing gap, and the lubricant accommodating chamber 23 and the radial passages 25, 25 ... A liquid metal lubricant such as Ga alloy is supplied. The amount of lubricant filled is the end of the spiral groove slide bearing closest to the space in the vacuum vessel on the passage, that is, the thrust bearing 22b at the bottom of the figure.
From the internal spiral groove and bearing gap, the lubricant containing chamber, the radial passage, and the space S1 formed by the small diameter portion, the volume of the internal space in which the lubricant can flow is approximately 20% to 90%. Is desirable. As a result, the leakage of the lubricant can be suppressed, and the lubricant can be spread to each part without excess or deficiency.

The opening position of the radial passage may be in the region where the spiral groove is formed. Also, since some of the radial passages, where the lubricant is almost completely lost by its own weight when the rotation is stopped, form gas passages, even if a gas were generated inside, gas bubbles would lubricate the outside through this gas passage. The drug is discharged without leakage.

Further, in the above-mentioned embodiment, the spiral groove 19a, 19b, 21a is formed on the outer surface of the fixed body 15,
The invention is not limited to this, and each spiral groove may be formed on the opposite bearing surface, that is, the inner surface of the rotating body 12. Also in that case, the radial passage 25 is formed so as to open at a position corresponding to the region having the spiral groove. This also applies to each of the following embodiments.

In the embodiment shown in FIGS. 5 and 6, each radial passage 25 is opened in the bearing surface between the adjacent spiral grooves 19a. In this case, a tapered opening 25a is formed in each opening along the direction of rotation P of the rotating body 12.

Accordingly, for example, when rotation is stopped, even if the bearing surface of the opening portion of the radial passage 25 between the rotating body 12 and the fixed body 15 is brought into close contact with the rotating surface, the liquid metal lubricant does not rotate in the radial direction. It is reliably supplied from the passage 25 through the tapered opening 25a to between the bearing surfaces. Therefore, the rotation start is facilitated, and the bearing surface is hardly damaged.

In the embodiment shown in FIG. 7, the length L1 of the spiral groove on each side of the spiral grooves 19a, 19b of the herringbone pattern,
L2 is different, and L1> L2. A plurality of radial passages are formed near the outer ends of the spiral grooves of each set.
25 is opened. Each radial passage 25 communicates with a lubricant containing chamber 23 formed in the center of the fixed body 15.

According to this embodiment, at the time of high speed rotation, a relatively long spiral groove (L1) has a relatively short spiral groove (L1) in which the amount of lubricant taken in in the direction of the top T of the dogleg pattern is relatively short. L2) more than that. Thereby,
A part of the lubricant passes through the bearing region from the opening of the radial passage 25 formed at the outer end of the region of the relatively long spiral groove from the lubricant containing chamber 23, passes through the bearing region, and the region of the relatively short spiral groove. Flow returning to the lubricant accommodating chamber 23 occurs from the opening of the radial passage 25 formed at the outer end of the. Therefore, part of the lubricant circulates automatically during rotation and is reliably supplied to the bearing area.

In the embodiment shown in FIG. 8, the spiral grooves 19a and 19b of the herringbone pattern are continuously formed on both sides of the spiral groove, and the spiral grooves on the upper and lower sides of the fixed body in the figure are short and the spirals near the center are formed. The groove is formed long. A relatively long spiral groove near the center is connected to the small diameter portion 24 formed in the center of the fixed body 15. As a result, the spiral grooves 19a and 19b communicate with the space S1 of the small diameter portion 24. Further, the openings of the plurality of radial passages 25 are located near the outer ends of the relatively shorter spiral grooves.

According to this embodiment, the space S1 of the small diameter portion 24 is
The lubricant is supplied to the relatively long spiral groove, passes through the bearing area, and is opened from the opening of the radial passage 25 formed at the outer end of the relatively short spiral groove area to the lubricant containing chamber. Flow back to 23. In this way, some of the lubricant circulates automatically during rotation and is reliably delivered to the bearing area. Further, in this embodiment, it is not necessary to provide a radial passage in the region of the spiral groove which is relatively long, which facilitates manufacturing.

In the embodiment shown in FIGS. 9 and 10, the tip of the fixed body 15 constituting the thrust slide bearing 22a is opened near the outer peripheral portion in the region of the spiral groove 21a of the tip surface.
The individual concave portions 31, 31, ... Are drilled. In other words, the spiral groove 21a of the herringbone pattern that has a circle shape.
In this region, the recess 31 is provided in the outer peripheral portion where the lubricant is diluted during operation. The depths of these recesses 31 are 50 times or more the depth of the spiral groove, and the lubricant is contained therein. Therefore, at the time of rotation start or continuous rotation, the lubricant in these recesses flows to the spiral groove and the bearing surface of the thrust bearing and is supplied to the bearing gap. It should be noted that the spiral groove 21 of the circular herringbone pattern
The lubricant is supplied from the opening 23a of the lubricant accommodating chamber 23 to the inside area of a. Fabrication of the recess 31 is relatively easy.

A similar concave portion may be provided near the outer end portion in the region of the spiral groove of the radial slide bearing. Although the embodiment described above is one in which the anode target is fixed to the cylindrical rotating body, the present invention is not limited to this, and as shown in FIG. The present invention can be applied to those arranged on the central axis. That is, the rotating shaft 13 is fixed to the upper part of the cylindrical rotating body 12 in the figure, and the anode target 11 is fixed thereto. Further, a cylindrical fixed body 15 having a bottom is provided so as to surround the rotating body 12. At the upper end opening 15b of the fixing body 15 shown in the figure, an opening closing body 16 is provided with a plurality of bolts 16a.
It is concluded by. On the outer circumference of the fixed body 15, a ferromagnetic cylinder 41 functioning as a rotor cylinder of a motor and a copper outermost cylinder 42 fitted to the outside thereof are coaxially arranged. The upper end 41a of the ferromagnetic cylinder 41 is attached to the rotary shaft 13
It is firmly mechanically fixed to. The opening blocker 16 is
It is in contact with the upper end surface of the rotating body 12, and its contact surface has a spiral groove.
21 are formed. Around the rotation axis of the lower half of the inner peripheral wall and the rotation body 12 close to the rotation axis of the opening blocker 16,
A cavity 26 that is hollowed out in a circumferential shape is formed. The cavity 26 is provided in communication with the inner end of the bearing gap of the thrust bearing 22b. Further, in the middle of communicating with the space inside the vacuum container through the gap between the cavity 26 and the outer peripheral wall of the fixed body and the inner peripheral wall of the ferromagnetic cylinder, a minute gap Q for preventing lubricant leakage and a folded portion 43 in the radial direction. Is provided. In addition, a coating film to which the liquid metal lubricant adheres and reacts may be formed on the inner surface of the folded portion 43. As a result, even if a part of the lubricant leaks out to around this, it will adhere to the inner surface of the folded-back portion 43 and will not leak out to the outside.

Therefore, the rotating body 12 is provided with a lubricant accommodating chamber 23 whose center portion is a hole bored along the axial direction. The illustrated lower end opening 23a of the lubricant accommodating chamber 23
Is located in the center of the inside of the circular spiral groove 21a at the lower part of the drawing and communicates with the bearing gap of the thrust bearing 22a. The radial passages 25, 25 ... Extend from the lubricant accommodating chamber 23, and open in the vicinity of each outer end portion in the region of the spiral groove 19a, 19b of the herringbone pattern of each radial plain bearing 20a, 20b. There is. This ensures that the lubricant is supplied to each slide bearing. It should be noted that the radial bearing may be formed with a recess as shown in FIGS. 9 and 10 so as to open in the spiral groove region. As a result, the radial passage can be limited to only the passage 25 opening to the small diameter portion 24. Further, a reaction layer of the bearing base material and the lubricant may be thinly formed in advance on the slide bearing surface having at least the spiral groove of each bearing constituent member. Alternatively, a reaction layer of the bearing base material and the lubricant may be thinly formed on each bearing surface by vacuum heat treatment. In this case, the filling amount of the lubricant is larger than that consumed by the formation of the reaction layer, and it is desirable to inject the lubricant.

The metal lubricant is Ga or Ga-I.
An alloy mainly composed of Ga such as an n alloy or a Ga—In—Sn alloy can be used, but is not limited thereto. For example, Bi—In—Pb containing a relatively large amount of bismuth (Bi).
-Sn alloy or In-B containing a relatively large amount of In
An i alloy or an In-Bi-Sn alloy may be used. Since these have a melting point of room temperature or higher, it is desirable to preheat the metal lubricant to a temperature equal to or higher than the melting point before rotating the anode target and then rotate the target.

[0023]

As described above, according to the present invention,
The liquid metal lubricant is surely spread between the bearing surfaces of the slide bearing during both rotation start and continuous high-speed rotation, damage to the bearing surface is prevented in advance, and stable dynamic pressure type slide bearing operation is maintained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of the same as FIG.

FIG. 3 is a top view showing a main part of FIG.

FIG. 4 is a top view showing a main part of FIG.

FIG. 5 is a longitudinal sectional view of an essential part showing another embodiment of the present invention.

6 is a transverse sectional view taken along line 6-6 of FIG.

FIG. 7 is a longitudinal sectional view of a main part showing still another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a main part showing still another embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of a main part showing still another embodiment of the present invention.

FIG. 10 is a top view showing a main part of that of FIG. 9;

FIG. 11 is a top view of essential parts showing still another embodiment of the present invention.

[Explanation of symbols]

 11 ... Anode target, 12 ... Rotating body, 15 ... Fixed body, 18 ... Vacuum container, 19a, 19b, 21a, 21b ... Helical groove, 20a, 20b ... Radial plain bearing, 22a, 22b ... Thrust plain bearing, 23 ... Lubrication Agent storage chamber, 25 ... Radial passage, 31 ... Recess.

Claims (4)

[Claims] 1. A rotating body to which an anode target is fixed,
A fixed body which is fitted coaxially to the rotating body and holds the rotating body rotatably, a dynamic pressure slide bearing having a spiral groove provided in a fitting portion of the rotating body and the fixed body, and the bearing. In a rotating anode type X-ray tube provided with a supplied metal lubricant which is liquid at least during operation, a part of the lubricant is contained in the fixed body or the rotating body located on the central axis of rotation. A lubricant storage room is provided,
Further, at least one lubricant passage is formed, one end of which communicates with the lubricant storage chamber and the other end of which opens into a region of the bearing where the spiral groove is formed. X-ray tube. 2. The rotating anode type according to claim 1, wherein the spiral groove of the dynamic pressure sliding bearing has a herringbone pattern, and the opening of the lubricant passage is located at least near the grooved outer end portion of the pattern on one side. X-ray tube. 3. The rotary anode type X-ray tube according to claim 2, wherein the spiral grooves of the herringbone pattern are different from each other in length of the spiral grooves on both sides. 4. A rotating body to which an anode target is fixed,
A fixed body which is fitted coaxially to the rotating body and holds the rotating body rotatably, a dynamic pressure slide bearing having a spiral groove provided in a fitting portion of the rotating body and the fixed body, and the bearing. In a rotary anode type X-ray tube provided with a supplied metal lubricant which is liquid at least during operation, a region where a spiral groove of the slide bearing is formed in a rotating body or a fixed body which constitutes the slide bearing. The rotary anode type X is characterized in that at least one concave portion is formed in which the lubricant is accommodated inside.
Line tube.