JPH06302288A - Rotary anode type x-ray tube - Google Patents

Abstract

PURPOSE:To positively catch unreqauired foreign matter generated on or reached to a bearing section and to retain stable dynamic pressure sliding bearing operation without disturbing generation of dynamic pressure by means of helical grooves by providing recessed parts for accommodating the foreign matter to a region for scraping up a lubricant by means of the helical grooves during the rotating operation of the dynamic pressure sliding bearing. CONSTITUTION:A region for scraping up a lubricant by means of heringbone.patterned helical grooves 19a, 19b, 22a, 22b during the rotating operation of a dynamic pressure sliding bearing and having a max. or nearly max. value of lubricant pressure is provided with a recessed part 21 for accommodating foreign matter and comprising circumferentially formed deep grooves at two places, respectively. Thus, even if foreign matter is mixed in the lubricant, the foreign matter and the lubricant enter the recessed parts 21 for accommodating the foreign matter by means of the helical grooves for gradual accumulation. The recessed parts for accommodating the foreign matter have depth sufficiently deeper than the helical grooves, being not readily filled with the foreign matter. Thus, lubricant scraping up action and dynamic pressure generation action by means of the helical grooves are stably continued without any assistance.

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 this is supported by an electromagnetic coil arranged outside a vacuum container. While energizing and rotating at high speed, the electron beam emitted from the cathode is applied to the anode target to emit X-rays. The bearing may be a rolling bearing such as a ball bearing, or may be a gallium (Ga) or gallium-indium-tin (Ga-In-Sn) alloy that has at least one set of herringbone pattern spiral grooves formed on the bearing surface. It consists of a dynamic pressure type sliding bearing that uses a metal lubricant that turns into a liquid during various operations. An example using the latter slide bearing is
For example, JP-B-60-21463 and JP-A-60-97.
536, JP-A-60-117531, and JP-A-62-162.
No. 287555, Japanese Patent Laid-Open No. 2-227947, Japanese Patent Laid-Open No. 2-227948 and the like.

[0003]

In a rotary anode type X-ray tube provided with a dynamic pressure type sliding bearing using such a liquid metal lubricant, the lubricant is supplied from the peripheral portion of the spiral groove of the herringbone pattern during the rotating operation. Dynamic pressure is generated by being scraped up in the part of the central part that is folded back into a dogleg. 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 rotating operation. However, when the rotation stops, at least a part of the bearing surface comes into contact with itself 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 there is no lubricant between the bearing surfaces, rubbing will occur and the bearing surface will be scraped at the next rotation start. When the bearing constituent member is made of a relatively soft material such as iron or an iron alloy, the bearing constituent member is particularly abraded, so that a large amount of foreign matter such as fine iron powder is generated and easily mixed with 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 the foreign matter is also mixed in the lubricant. When such foreign matter gradually accumulates inside the herringbone pattern spiral groove of the bearing, the depth of the groove gradually becomes shallower, the required dynamic pressure is not generated, and the performance of the dynamic pressure bearing deteriorates. I will end up.

On the other hand, in a dynamic pressure type slide bearing having a herringbone pattern groove, the idea of providing a large number of circumferential or independent recesses for accumulating lubricant and foreign matter outside the area of the herringbone pattern spiral groove is disclosed in, for example, Japanese Unexamined Patent Publication 1-1
No. 41218, No. 141219, etc. However, even if the recess is provided outside the herringbone pattern spiral groove region, the probability that foreign matter will enter the hollow and be accommodated 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 can reliably trap undesired foreign matter that is generated or reaches the bearing portion, and that dynamic pressure is generated by the herringbone pattern spiral groove. An object of the present invention is to provide a rotating anode type X-ray tube capable of maintaining stable dynamic pressure type sliding bearing operation without hindrance.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a rotary anode type X-ray in which a concave portion for accommodating a foreign substance is formed in a region where a lubricant is scraped by a spiral groove of a herringbone pattern during a rotational operation of a dynamic pressure sliding bearing. It is a tube.

[0007]

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

[0008]

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, the disk-shaped anode target 11 made of a heavy metal has a bottomed cylindrical rotor 1.
A rotating shaft 13 projecting from one end of the nut 2 is integrally fixed by a nut 14. The rotating body 12 includes an inner cylinder 12a made of tool steel, a ferromagnetic cylinder 12b such as iron fitted to the outer periphery thereof, and a good conductor cylinder 12c such as copper fitted to the outer side thereof. Is equipped with. A cylindrical fixed body 15 is inserted inside the rotary body 12. A fixed body small diameter portion 17 having a reduced outer diameter is formed at the lower end of the fixed body 15 in the figure. A ring-shaped opening closing member 16 is fixed to the lower end of the rotary member in the figure by surrounding the fixed member small diameter portion 17 in close proximity with a plurality of bolts. The small fixed body diameter portion 17 is airtightly joined to a vacuum container 18 made of glass through an auxiliary ring 17a made of an iron alloy and a seal ring 17b.

At the fitting portion between the cylindrical rotary body 12 and the fixed body 15, there is formed a dynamic pressure type herringbone pattern spiral groove slide bearing as shown in the above-mentioned respective publications. That is, the spiral grooves 19a, 1 of the herringbone pattern are formed on the outer peripheral wall of the fixed body 15 at predetermined intervals in the axial direction.
9b is formed, and two sets of radial plain bearings 20 are formed.
a and 20b are configured. The herringbone pattern spiral grooves 19a and 19b forming each slide bearing are
The V-shaped grooves are axially separated from each other, and
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 scraped by the spiral groove during the rotation operation and the lubricant pressure becomes the maximum value or a value close to it, the foreign matter accommodating recess formed of the deep groove formed in the circumferential shape is formed. 21 and 21 are provided, respectively. The foreign matter containing recess 21 has a depth of about 0.5 mm and an axial width of about 1 mm.
mm.

Further, 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, and one thrust slide bearing is formed. 23a is configured. The depth of each groove is still about 20 μm. And
A fold-back region in the middle of the substantially V-shaped spiral groove 22a, that is, a region where the lubricant is scraped up by the spiral groove and the lubricant pressure reaches a maximum value or a value close to it, is formed by a circular deep groove. A recessed portion 24 is formed.
The recess 24 has a depth and a radial width of about 0.5 mm.
Is. Similarly, on the upper surface of the opening blocker 16, a circular herringbone pattern spiral groove 22b shown in FIG. 4 is formed, and the other thrust slide bearing 23b is formed. The depth of each groove is still about 20 μm, and the foreign matter accommodating concave portion 24 also formed of a circular deep groove is formed in the region where the lubricant is scraped up by the spiral groove and the lubricant pressure reaches a maximum value or a value close to it. Has been done. This recess 2
4 also has a depth and radial width of about 0.5 mm.

Both the bearing surfaces of the rotating body and the fixed body face each other with a bearing gap of about 20 μm during the rotating operation. The fixed body 15 is provided with a lubricant accommodating chamber 25 that is a hole formed in the center of the fixed body 15 along the axial direction. The illustrated upper end opening 25a of the lubricant accommodating chamber 25 has a circular spiral groove 22a at the upper part of the drawing.
Is located in the center of the inside and communicates with the bearing gap of the thrust bearing 23a. Lower end portion 2 of the lubricant containing chamber 25 in the drawing
5b extends to a position in the vicinity of the lower thrust spiral groove slide bearing 23b and terminates. The outer peripheral wall of the intermediate portion of the fixed body 15 is shaved to reduce the small diameter portion 26.
Are formed. Then, at five locations in the axial direction, one end is connected to the lubricant accommodating chamber 25 and the other end opening is fixed body 15
The radial passages 27, 27 ...
It is formed axially symmetrically at intervals of degrees. The radial passage 27 at the central portion in the axial direction is open to the small diameter portion 26. The remaining four radial passages 27 ... Are the spiral grooves 19 of the herringbone pattern of each radial plain bearing 20a, 20b.
The openings are formed in the vicinity of the outer end in the area 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 indicated by an arrow P. A radial passage 27 extending from the lubricant accommodating chamber 25 is opened in this portion, so that the lubricant filled in the lubricant accommodating chamber and the radial passage is quickly supplied to the bearing region at the time of rotation start and continuous rotation. To be done. Therefore, the lubricant is always interposed between the bearing surfaces. Further, since the lubricant is also supplied from the lubricant containing chamber 25 to the circumferential space S formed by the small diameter portion 26 via the radial passage 27, the lubricant is distributed even on the bearing surface having no spiral groove. Furthermore, the lubricant is also supplied to the thrust bearing through the opening 25a of the lubricant containing chamber. Thus
Lubricant is reliably supplied to all bearing surfaces.

As described above, in the spiral groove of each bearing, the bearing gap, the lubricant accommodating chamber communicating therewith, the radial passages, and the space S formed by the small diameter portion, a liquid metal lubricant such as Ga alloy is used. Is being supplied. Even if foreign matter is mixed with the lubricant, the foreign matter is efficiently collected together with the lubricant by the spiral groove in the region where the lubricant pressure is maximum during the rotating operation, and the foreign matter is formed by the deep groove formed therein. It enters the recesses 21 and 24 for accommodation and gradually accumulates. Since the depth of the foreign matter accommodating recess is sufficiently deeper than that of the spiral groove, it is not easily filled with the foreign matter. Therefore, it is less likely that the depth of the spiral groove will be shallow or the bearing gap will be narrowed. In addition, the lubricant scraping action and the dynamic pressure generating action by the spiral groove are maintained as they are. In this way, the operation of the dynamic slide bearing is guaranteed for a long time. Further, a relatively clean lubricant is supplied to the spiral groove bearing from the lubricant accommodating chamber and the radial passage, and 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 matter accommodating recesses 21 and 21 formed of deep grooves are continuously formed. As a result, the foreign matter is scarcely accumulated in the spiral groove, is scraped along the spiral groove, and is captured and accommodated in the foreign matter accommodation recess. 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 is a circular herringbone pattern spiral groove 22a forming a thrust bearing.
And a recess 24 for accommodating a foreign matter, which is a deep groove, are continuously formed. According to this, as in the above-described embodiment, the accumulation of foreign matter in the spiral groove is suppressed.

In the embodiment shown in FIG. 7, the foreign matter containing recess 21 is provided.
Is formed on the inner peripheral surface of the inner cylinder 12a which is a bearing constituent member of the rotating body 12. Similarly, in the thrust bearing as well, the foreign matter accommodating recess may be formed in the bearing constituent member facing the bearing constituent member 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 foreign matter accommodating concave portion 21 formed of a deep groove has a narrow portion 21a and a wide portion 21a.
b and b are alternately and continuously formed. According to this
Since the foreign matter is likely to stay in the wide portion 21b, the foreign matter capturing action is enhanced.

In the embodiment shown in FIG. 9, the lubricant is scraped up in the spiral groove, and the foreign substance accommodating recess 2 formed of a plurality of circular recesses is formed in the region where the lubricant pressure is at or near the maximum value.
1 are formed at predetermined intervals in the circumferential direction. Foreign matter is deposited 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 scraped up in the spiral groove to form the deepest groove folded portion (depth d1) where the lubricant pressure is maximized, and both ends (depth d2) are formed shallow. According to this, a large amount of foreign matter mixed in the lubricant is accumulated in the deep groove folding portion (24). In addition, (a) of the figure
Is a partial side view of the fixed body 15, and FIG. 6B is a partial vertical cross-sectional view taken along line bb of FIG.

Incidentally, the structure for forming the foreign matter accommodating concave portion or the spiral groove itself shown in each of the above embodiments deeply in the central portion,
It is also possible to appropriately combine each bearing portion. Further, it is also applicable to a structure in which a rotating body is provided on the center axis of rotation and a fixed body is coaxially fitted and arranged around the rotating body. Furthermore, the recess for accommodating foreign matter may be formed in either or both of the fixed body and the rotating body that form the bearing.

Further, the liquid metal lubricant is Ga, Ga
-In alloy or G such as Ga-In-Sn alloy
The material mainly composed of a can be used, but is not limited thereto, and for example, Bi-In-containing a relatively large amount of bismuth (Bi).
Pb-Sn alloy or In containing a relatively large amount of In
-Bi alloy or 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.

[0021]

As described above, according to the present invention,
The foreign matter is scraped together with the lubricant in the herringbone pattern spiral groove and is trapped and accumulated in the foreign matter accommodating recess or the deep groove portion of the spiral groove. Therefore, it is less likely that the main portion of the spiral groove will be shallow or the bearing gap will be narrowed. In this way, a stable and necessary and sufficient dynamic pressure slide bearing operation is maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an 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.

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

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

FIG. 6 is a top view of a main part 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 an essential 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 container, 19a, 19b, 22a, 22b ... Helical groove, 20a, 20b ... Radial plain bearing, 23a, 23b ... Thrust plain bearing, 21, 24 ... A recess for accommodating foreign matter.

Claims (4)

[Claims] 1. A rotating body to which an anode target is fixed,
A fixed body that is coaxially fitted to the rotating body and rotatably holds the rotating body; and a dynamic pressure slide bearing having a herringbone pattern spiral groove provided in the fitting portion of the rotating body and the fixed body. A rotary anode type X-ray tube provided with a metal lubricant that is liquid at least during operation supplied to the bearing, wherein at least one of a fixed body and a rotary body constituting the dynamic pressure sliding bearing is rotated. A rotating anode type X-ray tube, wherein a concave portion for accommodating foreign matter is formed in a region where the lubricant is scraped by the spiral groove of the herringbone pattern during operation. 2. The rotary anode type X-ray tube according to claim 1, wherein the foreign matter accommodation recess is formed in a circumferential shape on at least one of the rotating body and the fixed body. 3. The rotary anode type X-ray tube according to claim 2, wherein the foreign matter accommodating recess is continuous with the spiral groove of the herringbone pattern. 4. A rotating body to which an anode target is fixed,
A fixed body that is coaxially fitted to the rotating body and rotatably holds the rotating body; and a dynamic pressure slide bearing having a herringbone pattern spiral groove provided in the fitting portion of the rotating body and the fixed body. A rotary anode X-ray tube provided with a metal lubricant that is liquid at least during operation supplied to the bearing, wherein the lubricant is retained in the spiral groove of the herringbone pattern during the rotational operation of the hydrodynamic slide bearing. A rotary anode type X-ray tube characterized in that the depth of the spiral groove in the region to be scraped is formed deeper than the groove depth in other regions.