JP2989086B2 - Rotating anode X-ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As is well known, a rotating anode type X-ray tube has a disk-shaped anode target supported by a rotating body and a fixed body having bearings therebetween and attached by an electromagnetic coil disposed outside a vacuum vessel. The X-rays are emitted by applying an electron beam emitted from the cathode to the anode target while rotating at a high speed. The bearing may be a rolling bearing such as a ball bearing, or a gallium (Ga) or gallium-indium-tin (Ga-In-Sn) alloy having at least one set of herringbone pattern helical grooves on the bearing surface. It consists of a dynamic pressure-type sliding bearing that uses a metal lubricant that becomes liquid during various operations. An example using the latter plain bearing is
For example, JP-B-60-21463, JP-A-60-97
536, JP-A-60-117531, JP-A-62-2
No. 287555, JP-A-2-227947, and JP-A-2-227948.

[0003]

In a rotating anode type X-ray tube provided with a dynamic pressure type slide bearing using such a liquid metal lubricant, during rotation operation, the lubricant flows from the periphery of the spiral groove of the herringbone pattern. A dynamic pressure is generated by being raked up at the center of the central portion that is folded back. The spiral groove of the herringbone pattern has a depth of about 20 μm, and the bearing surface is kept in a non-contact state at a bearing interval of about 20 μm during the rotation operation. However, when the rotation stops, at least a part of the bearing surface comes into contact with the weight of the rotating body. If the lubricant is interposed as a thin film on the contact surface, the bearing surfaces will not be rubbed with each other even at the start of the next rotation, and no damage will be caused thereby. However, when the rotation of the bearing surface in the region where the lubricant becomes thin during operation is stopped, the lubricant may not exist between the contacted bearing surfaces. If the lubricant does not exist between the bearing surfaces, at the next rotation start, rubbing occurs and the bearing surface is scraped. When the bearing component is made of a relatively soft material such as iron or an iron alloy, the bearing component is particularly cut off, and a large amount of foreign matter such as fine iron powder is generated, and is easily mixed into the lubricant. Alternatively, it is conceivable that a reaction product is generated by the reaction between the bearing constituent member and the liquid metal lubricant, and this foreign matter is mixed into the lubricant. When such foreign matter gradually accumulates inside the herringbone pattern spiral groove of the bearing, the depth of the groove gradually decreases, and the required dynamic pressure is not generated, and the performance of the dynamic pressure bearing is reduced. I will.

On the other hand, in a hydrodynamic sliding bearing having a herringbone pattern groove, the idea of providing a large number of circumferential or independent depressions for storing lubricant and foreign matter outside the region of the herringbone pattern spiral groove is disclosed in, for example, Japanese Patent Application Laid-Open No. HEI 9-163572. 1-1
No. 41218 or 141219. However, even if the dent is provided outside the herringbone pattern spiral groove region, the probability that foreign matter enters and is contained in the dent is small, and the foreign matter capturing effect cannot be sufficiently obtained.

The present invention has been made in view of the above circumstances, and it is possible to reliably capture undesired foreign matter which is generated or arrives at a bearing portion, and to reduce generation of dynamic pressure due to a herringbone pattern spiral groove. It is an object of the present invention to provide a rotating anode type X-ray tube capable of maintaining a stable dynamic pressure type sliding bearing operation without hindrance.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a rotary anode type X-ray having a foreign substance accommodating recess formed in a region where lubricant is raked up by a spiral groove of a herringbone pattern during a rotating operation of a dynamic pressure sliding bearing. Tube.

[0007]

According to the present invention, even if undesired foreign matter is generated in the bearing portion and mixed into the lubricant, the foreign matter is raked together with the lubricant in the spiral groove of the herringbone pattern and captured by the foreign matter accommodating recess. You. Then, the herringbone pattern spiral groove is prevented from being easily made shallow, and a stable and necessary and sufficient dynamic pressure sliding bearing operation is maintained for a long time.

[0008]

Embodiments of the present invention 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 4 has the following configuration. That is, the disk-shaped anode target 11 made of heavy metal is a rotating body 1 having a bottomed cylindrical shape.
2 is integrally fixed by a nut 14 to a rotating shaft 13 protruding from one end. The rotating body 12 includes an inner cylinder 12a made of tool steel, a ferromagnetic cylinder 12b such as iron fitted on the outer periphery thereof, and a good conductor cylinder 12c such as copper fitted on the outer cylinder. It has. A cylindrical fixed body 15 is inserted inside the rotating body 12. A fixed body diameter small portion 17 having a reduced outer diameter is formed at the lower end of the fixed body 15 in the figure. At the lower end in the figure of the rotating body, a ring-shaped opening closing body 16 is fixed by a plurality of bolts so as to closely surround the fixed body diameter small portion 17. The fixed body diameter small portion 17 is hermetically joined to a glass vacuum vessel 18 via an iron alloy auxiliary ring 17a and a seal ring 17b.

A helical groove slide bearing of a dynamic pressure type herringbone pattern as described in each of the above-mentioned publications is formed in a fitting portion between the cylindrical rotating body 12 and the fixed body 15. That is, the spiral groove 19a, 1 of the herringbone pattern is provided on the outer peripheral wall of the fixed body 15 at a predetermined interval in the axial direction.
9b, and two sets of radial sliding bearings 20
a, 20b. Herringbone pattern spiral grooves 19a and 19b constituting each plain bearing are:
The grooves in the shape of a letter are axially separated from each other,
The depth of each groove is about 20 μm. Then, in the intermediate region of each groove group, that is, in the region where the lubricant is raked up by the spiral groove in the rotation operation and the lubricant pressure becomes the maximum value or a value close to it, the foreign matter accommodating concave portion formed of the circumferentially formed deep groove 21 and 21 are provided respectively. The foreign matter accommodating recess 21 has a depth of about 0.5 mm and an axial width of about 1 mm.
mm.

As shown in FIG. 3, a spiral groove 22a having a circular herringbone pattern is formed on the upper end wall of the fixed body 15, that is, a surface perpendicular to the rotation axis. 23a is configured. The depth of each groove is also about 20 μm. And
A foreign substance containing a circular deep groove is provided in a folded area in the middle of the spiral groove 22a having a substantially U-shape, that is, in a region where the lubricant is raked up by the spiral groove and the lubricant pressure becomes a maximum value or a value close to the maximum value. Recess 24 is formed.
The recess 24 has a depth and a radial width of about 0.5 mm.
It is. Similarly, a circular herringbone pattern spiral groove 22b shown in FIG. 4 is formed on the upper surface of the opening closing body 16, and the other thrust slide bearing 23b is formed. The depth of each groove is also about 20 μm, and a foreign matter accommodating recess 24 also formed of a circular deep groove is formed in a region where the lubricant is raked up by the spiral groove and the lubricant pressure becomes a maximum value or a value close to the maximum value. Have been. This recess 2
No. 4 also has a depth and a radial width of about 0.5 mm.

Incidentally, the bearing surfaces of the rotating body and the fixed body face each other with a bearing gap of about 20 μm during the rotation operation. The fixed body 15 is provided with a lubricant accommodating chamber 25 formed of a hole whose center portion is hollowed out along the axial direction. The illustrated upper end opening 25a of the lubricant accommodating chamber 25 is formed in a circular spiral groove 22a in the upper part of the figure.
And communicates with the bearing gap of the thrust bearing 23a. The illustrated lower end portion 2 of the lubricant accommodating chamber 25
5b is extended to a position near the lower thrust helical groove sliding bearing 23b and is terminated. The fixed body 15 has a small-diameter portion 26 whose outer peripheral wall at the intermediate portion is cut.
Are formed. Each of the five ends in the axial direction has one end connected to the lubricant accommodating chamber 25 and the other end opened to the fixed body 15.
The radial passages 27, 27,...
It is formed axially symmetrically at intervals of degrees. The radial passage 27 at the axial center is open to the small diameter portion 26. The remaining four radial passages 27 are formed by the spiral grooves 19 of the herringbone pattern of each of the radial sliding bearings 20a and 20b.
Each opening is located near the outer end in the region a. These opening positions are regions where the liquid metal lubricant supplied to the spiral groove and the bearing gap becomes relatively thin when the rotating body 12 rotates at a high speed as shown by the arrow P. Since the radial passages 27 extending from the lubricant accommodating chamber 25 are opened in this portion, the lubricant filled in the lubricant accommodating chamber and the radial passage is quickly supplied to the bearing area both at the start of rotation and during continuous rotation. Is done. Therefore, the lubricant is always interposed between the bearing surfaces. Further, since the lubricant is also supplied from the lubricant accommodating chamber 25 through the radial passage 27 to the circumferential space S defined by the small diameter portion 26, the lubricant spreads to the bearing surface without the spiral groove. Further, the lubricant is also supplied to the thrust bearing from the opening 25a of the lubricant storage chamber. Thus,
Lubricant is reliably supplied to all bearing surfaces.

As described above, the spiral groove of each bearing, the bearing gap, and the space S defined by the lubricant accommodating chamber, each radial passage, and the small diameter portion communicating therewith are provided with a liquid metal lubricant such as a Ga alloy. Is supplied. Even if foreign matter is mixed in the lubricant, during the rotation operation, the foreign matter is efficiently collected by the spiral groove together with the lubricant in a region where the lubricant pressure is maximum, and the foreign matter is formed by the deep groove formed therein. It enters the recesses 21 and 24 for storage and gradually accumulates. Since the concave portion for accommodating foreign matter is deeper than the spiral groove, the concave portion is not easily filled with foreign matter. Therefore, there is little possibility that the depth of the spiral groove becomes shallow or the bearing gap becomes narrow. Further, the action of scraping the lubricant and the action of generating the dynamic pressure by the spiral groove are maintained as they are. In this way, the operation of the hydrodynamic sliding bearing for a long time is guaranteed. Further, relatively clean lubricant is supplied to the spiral groove bearing from the lubricant storage chamber and the radial passage, so that stable bearing operation is continued.

In the embodiment shown in FIG. 5, the spiral grooves 19a and 19b of the herringbone pattern and the foreign substance accommodating recesses 21 and 21 formed of deep grooves are formed continuously. As a result, the foreign matter is raked up along the spiral groove without being substantially deposited in the spiral groove, and is captured and accommodated in the concave part for accommodating the foreign matter. Therefore, the dynamic pressure bearing operation by the herringbone pattern spiral groove for a long time becomes more stable.

The embodiment shown in FIG. 6 shows a circular herringbone pattern spiral groove 22a constituting a thrust bearing.
And a foreign matter accommodating concave portion 24 formed of a deep groove. According to this, as in the above-described embodiment, the accumulation of foreign matter in the spiral groove is suppressed.

The embodiment shown in FIG.
Are formed on the inner peripheral surface of the inner cylinder 12a which is a bearing component of the rotating body 12. Similarly, in the thrust bearing, the foreign matter accommodating recess may be formed in the bearing component facing the bearing component in which the herringbone pattern spiral groove is formed. According to this, there is an advantage that the formation region of the spiral groove is not narrowed.

In the embodiment shown in FIG. 8, the concave portion 21 for accommodating a foreign substance formed of a deep groove has a narrow portion 21a and a wide portion 21a.
and b are alternately and continuously formed. According to this,
Since the foreign matter easily stays in the wide portion 21b, the foreign matter capturing action is enhanced.

In the embodiment shown in FIG. 9, the foreign matter accommodating recess 2 composed of a plurality of circular depressions is provided in a region where the lubricant is raked up in the spiral groove and the lubricant pressure is at or near the maximum.
1 are formed at predetermined intervals in the circumferential direction. Foreign matter accumulates in these recesses 21, 21,.

In the embodiment shown in FIGS. 10A and 10B, the groove depth of the herringbone pattern spiral groove 19a is
The lubricant is raked up in the spiral groove to form the groove turn-up portion (depth d1) where the lubricant pressure becomes maximum, and the both ends (depth d2) are gradually reduced. In this way, during the rotation operation of the hydrodynamic slide bearing,
The area where lubricant is raked up in the spiral groove of the Bonn pattern
The helical groove in the area becomes continuously deeper from other areas
Because it is urchin formed, foreign matter mixed in the lubricant to many deposition in the deep groove folded portion depths (24) Rutotomo
In addition, since there is no sharp step on the bottom of the groove,
Turbulence hardly Okoshira, stable bearing operation Ru guaranteed.
(A) of the figure is a partial side view of the fixed body 15,
FIG. 2B is a partial vertical cross-sectional view taken along line bb of FIG.

The configuration in which the concave portion for accommodating foreign matter or the spiral groove itself shown in each of the above embodiments is formed deep in the center portion is as follows.
Each of the bearing portions may be appropriately combined and configured. Further, the present invention can also be applied to a structure in which a rotating body is provided on a rotation center axis, and a fixed body is coaxially fitted around the rotating body. Furthermore, the foreign matter accommodating concave portion may be formed on one or both of the fixed body and the rotating body constituting the bearing.

The liquid metal lubricant is Ga, Ga
-In alloy or G such as Ga-In-Sn alloy
a-based material, but not limited thereto, for example, Bi-In- containing a relatively large amount of bismuth (Bi).
Pb-Sn alloy or In containing relatively large amount of In
-Bi alloy or In-Bi-Sn alloy may be used.
Since these materials have a melting point of room temperature or higher, it is desirable to rotate the metal lubricant after preheating the metal lubricant to a temperature equal to or higher than the melting point before rotating the anode target.

[0021]

As described above, according to the present invention,
The foreign matter is raked together with the lubricant in the herringbone pattern spiral groove, and is captured and deposited in the foreign matter accommodating concave portion or the deep groove portion of the spiral groove. Therefore, there is little possibility that the depth of the main part of the spiral groove becomes shallow or the bearing gap becomes narrow. In this way, stable and necessary and sufficient dynamic pressure sliding bearing operation is maintained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of FIG.

FIG. 3 is a top view showing a main part of FIG. 1;

FIG. 4 is a top view showing a main part of FIG. 1;

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

FIG. 6 is a main part top view showing still another embodiment of the present invention.

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

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

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

FIG. 10 is a side view and a partial cross-sectional view of a main part showing still another embodiment of the present invention.

[Explanation of symbols]

 11: anode target, 12: rotating body, 15: fixed body, 18: vacuum vessel, 19a, 19b, 22a, 22b: spiral groove, 20a, 20b: radial sliding bearing, 23a, 23b: thrust sliding bearing, 21, 24 ... Recess for accommodating foreign matter.

Claims (3)

(57) [Claims] A rotating body to which an anode target is fixed;
A fixed body fitted coaxially to the rotating body and rotatably holding the rotating body; and a dynamic pressure sliding bearing having a spiral groove of a herringbone pattern provided at a fitting portion of the rotating body and the fixed body. , at least during operation is supplied to the bearing in the rotating anode X-ray tube and a metal lubricant is liquid, at least one of the shaft receiving surface of the fixed body or the rotating body constituting the dynamic push Beri bearing The above-mentioned herringbone
A rotating anode type X-ray tube, wherein a foreign matter accommodating concave portion is formed intermittently or continuously along a circumferential direction in a region where a lubricant is raked up by a spiral groove of a pattern. 2. A dust containing recess, the rotary anode X-ray tube according to claim 2, characterized in that continuously spiral groove of a herringbone pattern. 3. A rotating body to which an anode target is fixed,
A fixed body fitted coaxially to the rotating body and rotatably holding the rotating body; and a dynamic pressure sliding bearing having a spiral groove of a herringbone pattern provided at a fitting portion of the rotating body and the fixed body. A rotating anode type X-ray tube comprising a metal lubricant that is supplied to the bearing and is at least liquid during operation, wherein the lubricant is provided in a spiral groove of the herringbone pattern during rotation of the dynamic pressure sliding bearing. the depth of the spiral groove of the raking is area, rotating anode X-ray tube, characterized in that it is continuously deeper as <br/> formed from other realm.