JP2003068239A - Rotation anode x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation anode X-ray tube in which a stable bearing operation can be maintained. SOLUTION: In the rotation anode X-ray tube comprising an anode target 12 arranged in a vacuum container 11 and a rotating mechanism for rotatably supporting the anode target 12, having dynamic pressure slide bearings arranged in bearing regions L1 to L4 where a rotor 13 is opposed to a fixed body 17 interposing the clearance of a first size, a liquid metal lubricant is supplied into the clearance in a non-bearing region L5 where the rotor 13 is opposed to the fixed body 17 interposing the clearance of a second size larger than the first size, and the anode target 12 is combined to the rotor 13 in the non- bearing region L5 directly or indirectly.

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 in which a rotary mechanism for rotatably supporting an anode target is provided with a dynamic pressure type slide bearing.

[0002]

2. Description of the Related Art A rotating anode type X-ray tube rotatably supports an anode target that emits X-rays by a rotating mechanism, irradiates an electron beam on the anode target that rotates at high speed, and the X-rays are emitted from the anode target. It has a structure that emits. The rotating mechanism that supports the anode target is composed of a rotating portion that rotates and a stationary portion that does not rotate, and a bearing is provided between the rotating portion and the stationary portion.

The bearing of the rotary anode type X-ray tube is a rolling bearing such as a ball bearing, or a spiral groove is formed on the bearing surface to form gallium (Ga) or gallium (Ga) -indium (In) -tin (Sn). ) A dynamic pressure type sliding bearing is used which supplies a liquid metal lubricant such as an alloy to a portion of a spiral groove.

Here, a conventional rotary anode type X-ray tube will be described with reference to FIG. 9 by taking a case of using a dynamic pressure type slide bearing as an example. Reference numeral 91 is a storage container, which is a storage container 91.
A rotary anode type X-ray tube 92 is housed therein. The rotary anode X-ray tube 92 is composed of a vacuum container 93 and the like.
A cathode 94 and an anode target 95 are arranged to face each other in the vacuum container 93. The anode target 95 is connected to a rotating mechanism 97 such as a rotating column 96, and is rotatably supported by the rotating mechanism 97. The rotating mechanism 97 includes a rotating body 98 to which the rotating columns 96 are connected and the rotating body 98.
It has a fixed body 99 and the like fitted to. The opening at the lower end of the rotating body 98 in the figure is sealed with thrust ring 100,
The fixed body 99 penetrates the thrust ring 100 and extends to the outside thereof.

Inside the fixed body 99, a hole 101 which forms a cooling passage through which a cooling medium flows is provided along the tube axis. One end of the fixed body 99 is airtightly bonded and fixed to a sealing ring 102 that seals the lower end of the vacuum container 93 in the drawing.
The stator 103 is arranged outside the vacuum container 93.

In the above structure, when the rotating anode type X-ray tube operates, the rotating body 98 and the anode target 95 are rotated at a high speed by the rotating magnetic field generated by the stator 103. In this state, the electron beam e generated by the cathode 94 is accelerated by a high voltage between the anode and the cathode, collides with the anode target 95, and X-rays are emitted from the anode target 95. X
The line is taken out through the output window W1 provided in the vacuum container 93 and the output window W2 provided in the storage container 91, as shown by an arrow Y.

Next, the anode structure of the rotary anode type X-ray tube will be described with reference to FIG. In FIG. 10, parts corresponding to those in FIG. 9 are denoted by the same reference numerals, and overlapping description will be partially omitted.

The rotary body 98 has, for example, a three-layer structure of an intermediate cylinder 98a directly connected to the rotary column 96, an inner cylinder 98b joined to the inside of the intermediate cylinder 98a, and an outer cylinder 98c joined to the outside of the intermediate cylinder 98b. It is configured. On the outer surface of the outer cylinder 98c, a blackened film 104 that has been blackened for heat release is formed. The opening at the lower end of the inner cylinder 98b in the figure is sealed with a thrust ring 100.
The fixed body 99 is fitted inside the inner cylinder 98b, and the lower end of the fixed body 99 penetrates the thrust ring 100 and further extends therebelow.

A dynamic pressure type slide bearing is provided on the fitting surface of the inner cylinder 98b and the fixed body 99. For example, dynamic pressure type sliding bearings 105a and 105b in the radial direction are provided at two locations on the outer peripheral surface of the fixed body 99, which are separated from each other in the tube axis direction. Also, the end surface of the fixed body 99 at the upper side in the drawing and the fixed body 9
Dynamic pressure type slide bearings 106a and 106b in the thrust direction are provided on the step surface below 9 in the figure.

Dynamic pressure type sliding bearing 105 in the radial direction
Helical grooves 111 having a helibone pattern as shown in FIG. 11A are formed in pairs at portions a and 105b. Thrust direction dynamic pressure type slide bearing 106
Helical grooves 112 having a helibone pattern as shown in FIG. 11B are formed in the portions a and 106b.

A liquid metal lubricant such as gallium or a gallium alloy is supplied to the fitting gap between the spiral groove 111, 112 and the inner cylinder 98b and the fixed body 99.

Two bearings 105a on the outer peripheral surface of the fixed body 99,
In the region sandwiched by 105b, the gap between the inner cylinder 98b and the fixed body 99 is wider than that of the bearings 105a and 105b,
A non-bearing region 113 that does not function as a bearing is provided. The gap of the non-bearing region 113 functions as, for example, a liquid metal lubricant storage portion.

The dimensions of the bearing portion such as the gap between the inner cylinder 98b and the fixed body 99 are set to an appropriate size so that the rotating portion can rotate stably, and the size thereof is the rotation speed of the rotating portion and the shape of the shaft. Depends on For example, in FIG.
In the case of the dynamic pressure type slide bearing as described above, a gap between the rotating body 98 and the fixed body 99, for example, the inner peripheral surface of the inner cylinder 98b and the fixed body 9 is formed.
The gap between the outer peripheral surface of 9 and the outer peripheral surface of 9 is set to about 1/1000 or less of the diameter of the bearing portion of the fixed body 99.

During operation of the rotating anode type X-ray tube, the temperature of the anode target 95 rises due to the irradiation of the electron beam.
When the heat of the anode target 95 is released to the outside of the tube, in a rotating anode type X-ray tube using a dynamic pressure type slide bearing, for example, the heat of the anode target 95 is transferred to the rotating body 98 to which the anode target 95 is connected, and the rotating body is further rotated. A method is used in which the liquid metal lubricant from 98 is transmitted to the fixed body 99 via the liquid metal lubricant, and the fixed body 99 discharges it outside the X-ray tube (Patent No. 2).
856531, Patent 2960085, Patent 29
30255 and US Pat. No. 5,838,763.
See the specification etc.).

[0015]

In the conventional rotary anode type X-ray tube, when heat generated by the anode target is released, for example, the heat is transferred from the rotating body to which the anode target is fixed to the fixed body through a dynamic pressure type slide bearing. It is released from the fixed body. In this method, in order to increase the heat transfer coefficient from the anode target to the rotating body, for example, when the area of the connecting portion between the anode target and the rotating body is widened, the temperature of the bearing portion increases during operation. As a result, the bearing surface may be roughened due to the mutual reaction between the material forming the bearing and the liquid metal lubricant, or the size of the bearing gap may change due to the reaction product, and stable bearing operation may not be maintained. is there.

Further, when the bearing surface of the dynamic pressure type sliding bearing is made of a refractory metal such as molybdenum alloy, it is difficult and expensive to process, which causes a problem of increasing the cost of the X-ray tube. Further, when the rotation-side bearing surface and the fixed-side bearing surface are mechanically rubbed with each other at the time of starting or stopping rotation, there is a problem that galling is likely to occur.

The dynamic pressure type slide bearing has the advantages of low noise and vibration during rotation, low wear and long life. However, a heat insulating structure is required to suppress the temperature rise of the bearing surface, which complicates the structure.

For example, when the rotating anode type X-ray tube enters the operating state and the rotating portion of the rotating mechanism starts rotating, the shearing energy of the liquid metal lubricant is converted into heat and the bearing portion generates heat. The heat of the anode target and the stator is also applied to the bearing portion, and the temperature of the bearing portion rises.

Therefore, the heat of the anode target and the heat of the rotating body due to the induction electromagnetic field are prevented from being transmitted to the bearing portion. For example, the cross-sectional area of the rotating column is reduced to reduce the amount of heat transfer, or the heat transfer path from the collision region of the electron beam on the anode target to the rotating column is lengthened.
In addition, there are a method of cooling by flowing a cooling medium through a cooling passage provided inside the fixed body, and a method of providing a blackening film on the outer surface of the rotating body to accelerate radiation and release heat.

The above method of reducing the heat transfer area of the rotating column has a problem that the mechanical strength becomes weak. Further, since the joining portion between the rotating column and the rotating body becomes high in temperature, mechanical strength at high temperature is required.

In the method of lengthening the heat transfer path, the deflection tends to occur as the weight of the anode target increases. C
An X-ray tube used for a T-apparatus or the like is likely to be bent because a strong centrifugal force is applied to the tube. In addition, if the heat transfer path is long, the study of the spring constant for stabilizing the rotation becomes complicated and a design error is likely to occur. However, when the heat transfer path is shortened, the amount of heat transferred from the anode target to the bearing portion is increased, the reaction between the member forming the bearing surface and the liquid metal lubricant is promoted, and the rotation characteristics are deteriorated.

The method of providing the blackening film raises the manufacturing cost, and when it is removed, it becomes a foreign substance to become a gas generation source and deteriorates withstand voltage characteristics.

There is also a method in which the heat of the anode target is positively escaped and cooled via the bearing surface or the like. With this method, a large amount of heat of a few hundred W level flows into the bearing,
It is necessary to increase the cooling capacity inside the bearing. Therefore,
The cooler capacity has to be improved, and it becomes large and expensive. Further, since the bearing surface becomes high in temperature, a metal material having heat resistance is used for the bearing surface in order to prevent the diffusion reaction with the liquid metal lubricant, which is expensive.

It is an object of the present invention to solve the above-mentioned drawbacks and to provide a rotating anode type X-ray tube capable of suppressing the temperature rise of the dynamic pressure type sliding bearing portion and maintaining stable bearing operation.

[0025]

According to the present invention, an anode target provided in a vacuum container is rotatably supported, and a rotating portion and a fixed portion are opposed to each other with a first gap having a predetermined size. In a rotary anode type X-ray tube including a rotating mechanism having a dynamic pressure type slide bearing provided in one region, the rotating portion and the fixed portion face each other with a second gap larger than the first gap and the second gap. Is provided with a second region filled with a liquid metal lubricant, and the anode target is directly on the rotating portion of the second region,
Alternatively, it is characterized by being indirectly connected.

[0026]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIG. Reference numeral 11 is a vacuum container that constitutes a rotary anode type X-ray tube, and a part thereof is shown in the drawing. A disk-shaped anode target 12 that emits X-rays into the vacuum container 11
Are arranged. The anode target 12 is formed of a heavy metal or the like, and is fixed to the outer peripheral portion of a cylindrical rotating body 13 made of a high melting point metal with a screw 14.

The rotating body 13 constitutes a rotating portion of a rotating mechanism that rotatably supports the anode target 12, and has, for example, a first portion 131 located at the upper end in the drawing and an outer diameter larger than that of the first portion 131 and in the middle. Positioned second part 13
2. The third portion 133 has an outer diameter larger than that of the second portion 132 and is located at the lower end in the figure. The highly conductive tubular rotating body 15 is joined to a part of the third portion 133.

The upper end portion of the first portion 131 penetrates the through hole of the anode target 12, and the anode target 1 is provided on the outer peripheral portion thereof.
2 is fixed. The lower end opening of the third portion 133 is sealed by the thrust ring 16. The fixed body 17 is fitted in the internal space provided, for example, from the first portion 131 of the rotating body 13 to the lower portion in the figure.

The fixed body 17 is made of, for example, a high melting point metal and constitutes a fixed portion of a rotating mechanism for rotatably supporting the anode target 12. The fixed body 17 includes a first small diameter portion 171 and a first small diameter portion 171 each having a small outer diameter at the upper end in the drawing.
Larger diameter portion 172 having a larger outer diameter than the larger diameter portion 172
The outer diameter is smaller than that of the second small diameter portion 173 at the lower end of the drawing. The fixed body 17 has a bottomed cylindrical shape whose bottom is the upper end portion, that is, the upper end portion of the first small diameter portion 171, and the second small diameter portion 173 penetrates the thrust ring 16, and the tip thereof is
It is airtightly joined to the vacuum container 11 made of glass through a tubular sealing member 18.

A pipe 20 is inserted into a hole 19 provided in the fixed body 17 along the pipe axis. The lower ends of the hole 19 and the pipe 20 in the drawing are opened outside the vacuum container 11. The upper end of the pipe 20 opens near the bottom inside the first small diameter portion 171 of the fixed body 17. At this time, in the fixed body 17, for example, as shown by an arrow C, the cooling medium introduced from the outside of the vacuum container 11 rises in the gap between the pipe 20 and the fixed body 17, and then descends in the pipe 20, Vacuum container 11
A cooling passage leading to the outside is formed.

A dynamic pressure type slide bearing is formed at the fitting portion between the rotating body 13 and the fixed body 17 having the above-mentioned structure. For example, a pair of herringbone pattern spiral grooves 22 are formed in upper and lower two locations on the outer periphery of the large diameter portion 172 of the fixed body 17, for example, in the areas designated by reference numerals L1 and L2, respectively, to form a dynamic pressure type sliding bearing in the radial direction. ing. Further, both upper and lower end surfaces of the large diameter portion 172 of the fixed body 17, for example, the reference symbol L3,
Helical groove 23 having a herringbone pattern is formed in each of the regions marked with L4 to form a dynamic slide bearing in the thrust direction.

Bearing region L in which a dynamic pressure type slide bearing is formed
In 1 to L4, the gap between the rotating body 13 and the fixed body 17 or the gap between the thrust ring 16 and the fixed body 17 is, for example, 1
It is in the range of 0 μm to 30 μm. Bearing area L1
Liquid metal lubricant is supplied to each of the gaps such as ~ L4 and the spiral grooves 22 and 23. The bearing surface on the rotor 13 side or the thrust ring 16 side may be a smooth surface or may be formed with a spiral groove.

Further, the rotating body 13 is located nearer the anode target 12 than the bearing regions L1 to L4, the fitting portion of the rotating body 13 and the fixed body 17, for example, at least the portion surrounded by the through hole of the anode target 12. The clearance between the fixed body 17 and the fixed body 17 is larger than the bearing regions L1 to L4, and a so-called non-bearing region L5 having almost no function as a bearing is provided. In the case of FIG. 1, the first portion 131 and the second portion 132 of the rotating body 13, the respective portions of the third portion 133 adjacent to the second portion 132, and the first small diameter portion 171 of the fixed body 17 are The non-bearing region L5 is provided in the portion facing in the tube axial direction.
Is provided.

The clearance of the non-bearing region L5 is, for example, 30 μm.
It is set in the range of m to 500 μm, and is set to a dimension such that the rotating body 13 and the fixed body 17 do not contact each other in a normal use state. Further, as shown enlarged in the circle R, the gap G between the rotating body 13 and the fixed body 17 in the non-bearing region L5 is filled with the liquid metal lubricant 28, as in the bearing regions L1 to L4.

When the X-ray tube having the above-described structure enters the operating state, the temperature of the anode target 12 rises due to the irradiation of the electron beam. The heat of the anode target 12 is dissipated by, for example, radiation. Part of the heat is transferred from the anode target 12 to the rotating body 13, and further from the rotating body 13 to the fixed body 1.
7 and is dissipated to the outside by, for example, a cooling medium flowing inside the fixed body 17.

In this case, the distance from the anode target 12 is shorter in the non-bearing region L5 than in the bearing regions L1 to L4. Therefore, most of the heat transfer from the rotating body 13 to the fixed body 17 is performed via the non-bearing region L5. Therefore, the heat passing through the bearing regions L1 to L4 is reduced, and the temperature rise in the bearing regions L1 to L4 is suppressed. As a result, mutual reaction between the material forming the bearing surface and the liquid metal lubricant is prevented, the roughness of the bearing surface and the dimensional change of the bearing gap are reduced, and stable bearing operation is maintained.

The non-bearing region L5 rises to 400 to 500 ° C. during operation. Therefore, the rotating body 13 and the fixed body 1
The material of the non-bearing surface of No. 7 may react with the liquid metal lubricant to grow a reaction layer. However, since the non-bearing region L5 has a large gap, adverse effects on the rotation characteristics are avoided.

In the case of the above embodiment, the anode target 1
2 is directly connected to the outer peripheral portion of the rotating body 13 portion of the non-bearing region L5. However, the anode target 12 may be fixed to a heat conducting member or the like, and the anode target 12 and the rotating body 13 part of the non-bearing region L5 may be mechanically or thermally indirectly connected via the heat conducting member. it can.

The above-mentioned structure has the rotating body 13 and the fixed body 1.
7. As the material of the thrust ring 16, for example, molybdenum or molybdenum alloy is used. However, instead of these materials, tungsten, a tungsten alloy, tantalum, a tantalum alloy, or the like can be used. Tungsten and tantalum have a property that they are less likely to be corroded by a liquid metal lubricant than molybdenum and molybdenum alloys.

However, on the surface of these materials located in the non-bearing region L5, chromium oxide, boride, vanadium nitride, carbide, boride, hafnium oxide, nitride, carbide, boride, titanium. Oxide, nitride, carbide, boride, tungsten, tungsten nitride, carbide, boride, molybdenum, molybdenum nitride, carbide, boride, zirconium oxide, nitride, carbide,
Boride, tantalum, tantalum nitride, carbide, boride, niobium, niobium nitride, carbide, boride, ruthenium, rhenium, osmium, iridium, boron nitride,
At least one selected from boron carbide, aluminum oxide, aluminum nitride, aluminum carbide, aluminum boride, silicon nitride, silicon carbide, silicon boride, diamond, carbon (including DLC and graphite), magnesium oxide, beryllium oxide. If a heat-resistant coating having a high melting point as a main component is applied, the temperature of the non-bearing region L5 during use can be increased and the cooling capacity of the anode target is increased.

In addition, the base material is a metallic material mainly composed of iron, and the bearing regions L1 to L4 and the non-bearing region L5 are included.
It is also possible to adopt a structure in which a heat resistant coating of the above-mentioned high melting point substance is applied to the surface thereof.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and overlapping description will be partially omitted.

In the case of this embodiment, the second portion 132 and the third portion 133 of the rotating body 13 are joined together at the portion X1. Further, the first small diameter portion 171 and the large diameter portion 172 of the fixed body 17 are joined at the portion indicated by the reference symbol X2. Then, the first portion 131 and the second portion 132 of the rotating body 13 indicated by the symbol A, and the first small diameter portion 171 of the fixed body 17 indicated by the symbol B.
Are made of molybdenum or a refractory metal selected from molybdenum alloy, tungsten, tungsten alloy, tantalum, and tantalum alloy. The third portion 133 of the rotating body 13 and the large diameter portion 172 and the second diameter of the fixed body 17 are The small portion 173 is formed of iron or iron-based metal such as iron, steel, alloy steel, iron-nickel alloy, iron-chromium alloy, or iron-nickel-chromium alloy.

In this case, the liquid metal lubricant is present in the joint portions X1 and X2. Most brazes are attacked by liquid metal lubricants. Therefore, the joining portions X1 and X2 are joined by an atomic diffusion joining method such as friction welding.

According to the above construction, the bearing regions L1 to L
The bearing surface of No. 4 is made of a metal mainly composed of iron. Since iron-based metal is easily processed, the bearing can be manufactured with high precision. In addition, the iron-based metal is a ferromagnetic material, so that the magnetic coupling efficiency with the rotating magnetic field is improved. In addition, the non-bearing area L
If a thin film of titanium nitride ceramics or the like is provided on the non-bearing surface of No. 5, the mechanical strength at high temperature is increased, and corrosion by the liquid metal lubricant can be prevented.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In FIG. 3, parts corresponding to those in FIG. 1 and FIG. 2 are denoted by the same reference numerals and overlapping description will be partially omitted.

In the case of this embodiment, the rotating body 13 has the structure shown in FIG.
Similar to the case of, the second portion 132 and the third portion 133 are joined at the joining portion X1, and the first portion 131 and the second portion 132 and the third portion 133 indicated by the symbol A are formed of different metals.

For example, the first portion 131 and the second portion 1
32 is made of a refractory metal, and the third portion 133 is made of a metal mainly composed of iron. The base material of the fixed body 17 is made of an iron-based metal that is easy and inexpensive to process, and as shown in an enlarged view within a circle R, the fixed body 17 is provided on the non-bearing surface on the fixed body 17 side in the embodiment of FIG. As described above, the heat resistant coating 31 is applied.

When the heat resistant coating is provided, for example, the portion other than the non-bearing surface of the base material is masked and the non-bearing surface is subjected to the CVD (chemical vapor deposition) method, the PACVD (plasma activated chemical vapor deposition) method, the MOCVD ( PVD such as metalorganic chemical vapor deposition) method or ion plating
(Physical Vapor Deposition) method, thermal spraying method, or the like, a method of depositing to a predetermined thickness of about 0.5 μm to 20 μm, or a method such as a molten salt bath dipping method or a heat treatment method in a gas atmosphere is adopted. .

In this case, as the material of the non-bearing surface of the rotating body 13, molybdenum, molybdenum alloy, tungsten, tungsten alloy, tantalum, tantalum alloy or the like is used.

Further, it is desirable to limit the formation of the heat resistant coating layer to a region of the non-bearing surface where the facing surfaces of the rotating body 13 and the fixed body 17 do not come into direct mechanical contact. However, if the heat-resistant coating layer has sufficiently high adhesion and wear resistance, it can be formed on the bearing surface. As the material of the heat resistant coating layer, a mixture of the substances described in the embodiment of FIG. 1 is used, or a material containing a slight amount of another substance is used.

FIG. 4 shows another embodiment of the present invention.
Will be described with reference to. In FIG. 4, parts corresponding to those in FIGS. 1 to 3 are denoted by the same reference numerals and overlapping description is partially omitted.

In the case of this embodiment, a cylindrical fixing ring 41 is provided in a part of the vacuum container 11, and a cylindrical fixing member 42 made of an insulating material is joined to a bent portion 41a bent inside the upper end thereof. Further, the tubular joining member 43 is joined to the inside of the tubular fixing member 42. The upper end of the fixed body 17 shown in the drawing penetrates the anode target 12 and is fixed inside the joining member 43 to be airtightly joined. An upper end portion of the fixed body 17 is formed by joining different metals at a joint portion indicated by reference numeral X3.

Further, a flange-like protruding portion 44 is formed at a portion of the fixed body 17 adjacent to the thrust ring 16. A through hole 45 penetrating from the upper end in the figure to the lower end in the figure is formed along the tube axis in the fixed body 17, and both upper and lower ends of the through hole 45 are open to the outside of the vacuum container 11. In addition, on the outer peripheral surface of the rotating body 13, the cylindrical outer rotating body 4 is provided.
6 is joined. The opening at the lower end in the figure of the through hole 45 constitutes, for example, the inlet of the cooling medium, the opening at the upper end in the figure constitutes, for example, the outlet of the cooling medium, and the cooling passage shown by the arrow C is formed in the fixed body 17.

Helical grooves are formed on the end surface of the rotating body 13 facing the upper surface of the protruding portion 44 of the fixed body 17 and on the surface of the thrust ring 16 facing the lower surface of the protruding portion 44 in the drawing. A thrust-direction dynamic pressure type slide bearing is formed, and bearing regions L3 and L4 are provided.

As in the case of FIG. 2, the rotating body 13 and the fixed body 17 are formed by joining different metal materials at the joint portions X1 and X2.

According to the above-mentioned structure, the fixed body 17 is fixed to the vacuum container 11 at two places, the upper and lower sides in the figure, and the bearing regions L1 to L4 are provided on one side when viewed from the anode target 12. In this case, since there is no dynamic pressure type slide bearing on the cathode side, the outer diameter of the rotating body 13 can be formed small, and the withstand voltage performance is secured. Further, since the cooling passage is linearly provided along the tube axis, more heat can be transferred to the cooling medium flowing in the fixed body 17. Therefore, the temperature rise in the bearing regions L1 to L4 is suppressed, corrosion of the bearing surface by the liquid lubricant is prevented, and stable bearing operation is maintained.

When the rotary anode type X-ray tube is used by grounding the anode, for example, by grounding the vacuum container 11 or the anode, the cylindrical fixing member 42 is made of a metal material instead of an insulating material such as ceramics or glass. To be done.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In FIG. 5, parts corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals and overlapping description is partially omitted.

In the case of this embodiment, the rotating body 13 and the fixed body 17 are divided into an upper portion J, an intermediate portion K, and a lower portion L with the two joint portions Y1 and Y2 separated from each other in the tube axis direction as boundaries. The opening of the lower portion L of the rotating body 13 is sealed by the thrust ring 16 and the opening of the upper portion J of the rotating body 13 is sealed by the second thrust ring 51.

In the rotating body 13 and the fixed body 17, the upper portion J and the lower portion L are formed of the same metal material, and the metal material different from the intermediate portion K is used.
The bearing regions L1 and L3 correspond to the rotating body 13 and the fixed body 1.
In the upper part J of 7, the bearing regions L2, L4 are in the lower part L
Are provided separately.

For example, a spiral groove 22 is formed on the outer peripheral surface of the upper portion J and the lower portion L of the fixed body 17, and a radial dynamic bearing is provided. Further, the spiral groove 23 is formed in each of the end surface of the upper portion J of the fixed body 17 facing the second thrust ring 51 and the end surface of the lower portion L of the fixed body 17 facing the thrust ring 16 to extend in the thrust direction. A hydrodynamic slide bearing is provided.

Below the thrust ring 16, a highly conductive tubular rotating body 52 is mounted, which induces an induced current by an externally arranged stator to generate a rotating force.

Also in this structure, the anode target 12 is directly connected to the non-bearing region L5, for example, the rotating body 13 in the intermediate portion K.

In the case of the above structure, the anode target 12
Bearing regions are separately provided on both sides of the. For this reason,
The load balance in the upper and lower bearing regions is well balanced, and the stability of the bearing is improved.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. Reference numeral 61 is an anode target that constitutes a rotating anode X-ray tube, and the anode target 61 is arranged in a vacuum container together with a cathode that generates an electron beam. The anode target 61 is, for example, a rotating column 62.
It is connected to a rotating mechanism 63 including a rotating body 64 and the like, and is rotatably supported by the rotating mechanism 63.

In order to reduce the heat transfer cross section, a part of the rotating support column 62, for example, the lower portion in the figure, is formed in a cylindrical shape.

The rotating body 64 constitutes a rotating portion of a rotating mechanism for rotatably supporting the anode target 61, and is, for example, an intermediate cylinder 64 joined to the outer peripheral surface of the lower end of the rotating column 62.
a and the inner cylinder 6 whose upper end is joined to the inner peripheral surface of the lower end of the rotating column 62 and whose lower end is joined to the inside of the intermediate cylinder 64a.
4b, and an outer cylinder 64c joined to the outside of the intermediate cylinder 64a has a three-layer structure. Outer cylinder 64
c is formed of copper or the like, and the intermediate cylinder 64a is formed of a ferromagnetic material such as an iron-based alloy.

The inner cylinder 64b is composed of a large-diameter portion b1 having a large outer diameter which constitutes a lower portion shown in the figure, and a small-diameter portion b2 which has an outer diameter smaller than that and constitutes an upper portion shown in the figure. The outer peripheral surface of the small diameter portion b2 is joined to the inner peripheral surface of the rotating column 62, and a part of the outer peripheral surface of the large diameter portion b1 is joined to the inside of the intermediate cylinder 64a. The opening at the lower end of the inner cylinder 64b in the figure is sealed with a thrust ring 65. Inner cylinder 6
A fixed body 66 is fitted inside 4b, and the fixed body 66 penetrates the thrust ring 65 and extends to the lower side in the drawing.

The fixed body 66 constitutes a fixed portion of a rotating mechanism that rotatably supports the anode target 61, and for example, a large diameter portion a fitted to a large diameter portion b1 of the inner cylinder 64b.
1, the first fitting in the small diameter portion b2 of the inner cylinder 64b
It is composed of a small diameter portion a2 and a second small diameter portion a3 penetrating the thrust ring 65 and extending downward.

A hole 67 is provided inside the fixed body 66 along the tube axis, and a pipe 68 is inserted into the hole 67.
As a result, a cooling medium such as insulating oil rises outside the pipe 68 and then descends inside the pipe 68, as shown by arrow C.

Further, a dynamic pressure type slide bearing is provided at a fitting portion between the inner cylinder 64b of the rotating body 64 and the fixed body 66, for example, at a portion where the inner cylinder 64b and the fixed body 66 face each other with a gap of a predetermined size. For example, dynamic pressure type slide bearings in the radial direction are provided at two locations L1 and L2 on the outer peripheral surface of the fixed body 66, which are separated from each other in the tube axis direction. In addition, the fixed body 66
Regions L3, L where the rotating portions face the upper and lower step surfaces of the drawing
4 is provided with a thrust direction dynamic pressure type slide bearing.

Helical grooves of a helibone pattern are formed on the bearing surface of each of the bearing regions L1 to L4, and the helical grooves and the gap between the rotor 64 and the fixed body 66 are filled with a liquid metal lubricant.

In the above structure, for example, the fixed body 66.
A region L sandwiched between two bearing regions L1 and L2 provided on the outer peripheral surface of the inner peripheral surface of the fixed body 66, and an inner peripheral surface of the inner peripheral portion 64b of the small diameter portion b2 of the fixed body 66. L
5. In the area L6 sandwiched between the upper end surface of the fixed body 66 and the bottom surface of the inner cylinder 64b shown in the figure, the clearance between the inner cylinder 64b and the fixed body 66 is larger than the clearance between the bearing areas L1 to L4. It is a so-called non-bearing region that is formed and functions little as a bearing.

The gaps between the non-bearing regions L, L5, L6 and the gaps between the bearing regions L1 to L4 are continuous, and the non-bearing regions L, L
A liquid metal lubricant is also filled in the gaps 5 and L6.

FIG. 6 is shown in an exaggerated manner for convenience of explanation. For example, the diameter of the fixed body 66 in the bearing regions L1 and L2 is, for example, 50 mm, and the clearance is, for example, approximately 10 to 50.
μm, the clearance in the bearing regions L3 and L4 is about 1
The gap between 0 to 50 μm and the non-bearing regions L5 and L6 is set in the range of 30 μm to 500 μm, for example.

FIG. 7 shows a structure in which the fixed body 66 is extracted from the rotary anode type X-ray tube. In Figure 7,
The parts corresponding to those in FIG. 6 are designated by the same reference numerals, and overlapping description will be omitted.

When the above rotary anode type X-ray tube enters the operating state, the anode target 61 generates heat due to the irradiation of the electron beam. This heat is transferred from the anode target 61 to the rotating column 6
2. Rotating column 62 to rotating body 64, and further rotating body 64
Is transferred to the fixed body 66 and is radiated by the cooling medium flowing through the cooling passage.

At this time, for example, the rotating body 64 part of the non-bearing area L5 is joined to the rotating column 62, and the rotating body 64 part of the non-bearing area L5 is more than the rotating body 64 part of the bearing areas L1 to L4. The mechanical and thermal paths with the anode target 61 are shortened. Therefore, most of the heat of the anode target 61 is transferred to the fixed body 66 via the joint between the rotating body 64 and the rotating strut 62 and the non-bearing area L5, and the temperature rise in the bearing areas L1 to L4 is suppressed. . Further, since the joint portion between the rotating body 64 portion and the rotating strut 62 in the non-bearing region L5 is closer to the anode target 61 than the bearing regions L1 to L4 and closer to the center of gravity of the rotating portion,
Can be joined at mechanically stable parts.

In the case of the above-mentioned structure, the joint between the rotating column 62 and the rotating body 64, for example, the intermediate rotating body 64a is also farther from the anode target 61 than the rotating body 64 portion in the non-bearing region L5. Therefore, the rotating column 62
The junction between the intermediate rotating body 64a and the intermediate rotating body 64a is not the main path of heat of the anode target 61, the temperature rise is suppressed, and the mechanical strength is prevented from deteriorating.

Further, since the temperature rise in the bearing regions L1 to L4 is suppressed, the heat transfer path from the anode target 61 to the fixed body 66 can be shortened and the deflection of the anode part can be reduced.
It becomes easy to adopt a heavy anode target.

Further, the joint between the rotating column 62 and the intermediate rotor 64a can be brought close to the anode target 61,
For example, the joint can be located near the center of gravity of the mechanically stable rotating anode part.

Further, a brazing material having a low melting point and good workability can be used for joining the rotary column 62 and the intermediate rotating body 64a, and the cost is reduced as compared with the case of using a brazing material of a high melting point metal. Further, the blackening treatment of the outer surface of the rotating body 64 is not always necessary, the decrease in withstand voltage is prevented, and the cost is reduced.

In FIG. 6, the cooling passage inside the fixed body is provided in a region where the rotating column 62 and the inner cylinder 64b are joined, and cooling is performed by a collision jet system in which a cooling medium is blown to the bottom of the cooling passage. Therefore, the heat transfer efficiency in the vicinity of the main heat transfer path is improved, and good heat release is possible. In this case, the cooling capacity of the cooling medium flowing in the fixed body may be small, and the cooling system can be downsized. Since the temperature rise is small, the conditions of materials used are relaxed and the selection range of materials is expanded.

For example, with respect to the structure of FIG. 6 and the structure of FIG. 10 described in the prior art, the material of the anode structure is the same, the average heat input of the anode target is 5 kW, and a general electric insulating oil is used as a cooling medium for cooling. 8-9 L / mi with the same flow rate
When calculated in the case of n, the structure of the invention of FIG. 6 is about 100 to 150 ° C. at the bearing-side end of the rotating column 62, and
The temperature of the outer rotating body 64c drops by about 150 ° C. on average.

Next, another embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In FIG. 8, parts corresponding to those in FIG. 6 are designated by the same reference numerals, and overlapping description will be partially omitted.

In the case of this embodiment, for example, a blocking wall 81 for closing the internal space of the rotary column 62 in the direction orthogonal to the tube axis is provided in the tubular section. And the blocking wall 81
The surface of the inner rotating body 64 on the side of the anode target 61 is joined to the surface on the side of the fixed body 66, and this joined portion is used as a heat transfer region. In this case, the non-bearing region L6 forms the main heat transfer path for the heat of the anode target.

In each of the above-described embodiments, the distance from the anode target to the non-bearing region of the rotor is shorter than the distance from the anode target to the rotor region of the bearing region. With this configuration, the amount of heat transferred from the rotating body to the fixed body via the non-bearing region is increased, and the temperature rise in the bearing region is suppressed.

However, the shape and material of the connecting portion connecting the rotating body portion and the anode target in the non-bearing area and the connecting portion connecting the rotating body portion and the anode target in the bearing area,
When the cooling conditions are different, the same effect can be obtained by making the former connection portion shorter in thermal distance than the latter connection structure portion.

For example, the connecting portion that connects the rotating body portion facing the non-bearing region and the anode target is formed with a structure or material that has a faster heat transfer rate, or the connecting portion that faces the non-bearing region is The rotating body part is formed of a structure or material that increases the amount of heat transfer per unit area at the same time, or the rotating body part facing the non-bearing area is It is formed in a structure or material that increases the amount of heat transfer per unit area. In these cases as well, when heat is transferred from the rotating body to the fixed body, a large amount of heat passes through the non-bearing region, and the temperature rise in the bearing region is suppressed.

Further, a spiral groove can be formed on the surface of the rotating body or the fixed body in the non-bearing region. When the spiral groove is provided, the spiral groove functions to retain the liquid metal lubricant in the gap when the rotating body rotates, and the heat transfer from the rotating body to the fixed body through the non-bearing area is performed well. Be seen.

The liquid metal lubricant used in each of the above-described embodiments includes, for example, G such as Ga or Ga-In-Sn.
A material mainly composed of a is used. However, a Bi-In-Pb-Sn alloy containing a relatively large amount of bismuth (Bi), or an In-Bi alloy containing a relatively large amount of In,
In-Bi-Sn alloy etc. can also be used.

Since the liquid metal lubricant has a melting point of room temperature or higher, it is desirable to preheat the liquid metal lubricant to a temperature higher than the melting point to turn it into a liquid state before rotating the anode target.

Further, according to the above structure, the average value of the input power to the anode target can be made relatively large, the bearing operating performance is stable for a long time, and the rotating anode type X-ray having a high cooling rate is provided. A tube is obtained. Furthermore, galling of the bearing part is prevented when starting and stopping rotation,
It is possible to obtain an inexpensive rotary anode type X-ray tube with stable bearing operation.

[0095]

According to the present invention, a rotary anode type X-ray tube which maintains stable bearing operation can be realized.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part for explaining an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an essential part for explaining another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of an essential part for explaining another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of an essential part for explaining another embodiment of the present invention.

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

FIG. 6 is a longitudinal sectional view of an essential part for explaining an embodiment of the invention.

FIG. 7 is a perspective view of the fixed body of FIG. 6 extracted.

FIG. 8 is a longitudinal sectional view of an essential part for explaining another embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of a main part for explaining a conventional example.

FIG. 10 is a cross-sectional view of the rotary anode portion of FIG.

11 is a perspective view for explaining the spiral groove of FIG.

[Explanation of symbols]

11 ... Vacuum container 12 ... Anode target 13 ... Rotating body 16 ... Thrust ring 17 ... Fixed body 22, 23 ... Helical groove 28 ... Liquid metal lubricant L1 to L4 ... Bearing area L5 ... Non-bearing area G: Gap in non-bearing area

Claims (11)

[Claims] 1. An anode target provided in a vacuum container,
A rotary anode type X-ray tube including a rotating mechanism that rotatably supports the anode target, and a rotating mechanism in which a dynamic pressure type slide bearing is provided in a first region in which a rotating portion and a fixed portion face each other with a first gap having a predetermined size. In the above, the rotating portion and the fixed portion are opposed to each other with a second gap larger than the first gap, and the second gap is provided with a second region filled with a liquid metal lubricant, and the anode target is the first region. Two
A rotary anode X-ray tube, characterized in that it is directly or indirectly connected to the rotating part of the region. 2. An anode target provided in a vacuum container,
A rotary anode type X-ray tube including a rotating mechanism that rotatably supports the anode target, and a rotating mechanism in which a dynamic pressure type slide bearing is provided in a first region in which a rotating portion and a fixed portion face each other with a first gap having a predetermined size. In, the rotating portion and the fixed portion are opposed to each other with a second gap larger than the first gap, and the second gap is provided with a second region filled with a liquid metal lubricant, and the second region has a surface. The rotating anode type X-ray tube, wherein the rotating portion is located at a position where the heat transfer time from the anode target is earlier than the rotating portion facing the first region. 3. An anode target provided in a vacuum container,
A rotary anode type X-ray tube including a rotating mechanism that rotatably supports the anode target, and a rotating mechanism in which a dynamic pressure type slide bearing is provided in a first region in which a rotating portion and a fixed portion face each other with a first gap having a predetermined size. In, the rotating portion and the fixed portion face each other with a second gap larger than the first gap, and the second gap is provided with a second region filled with a liquid metal lubricant, and the second region has a surface. The rotating anode type X-ray tube, wherein the rotating portion is located at a place where more heat of the anode target is transferred per unit area than the rotating portion facing the first region. 4. An anode target provided in a vacuum container,
A rotary anode type X-ray tube including a rotating mechanism that rotatably supports the anode target, and a rotating mechanism in which a dynamic pressure type slide bearing is provided in a first region in which a rotating portion and a fixed portion face each other with a first gap having a predetermined size. In, the rotating portion and the fixed portion are opposed to each other with a second gap larger than the first gap, and the second gap is provided with a second region filled with a liquid metal lubricant, and the second region has a surface. The rotating anode type X-ray is characterized in that the rotating portion is located at a place where more heat of the anode target is transferred per unit time and per unit area than the rotating portion facing the first region. tube. 5. An anode target provided in a vacuum container,
A rotary anode type X-ray tube including a rotating mechanism that rotatably supports the anode target, and a rotating mechanism in which a dynamic pressure type slide bearing is provided in a first region in which a rotating portion and a fixed portion face each other with a first gap having a predetermined size. In, the rotating portion and the fixed portion face each other with a second gap larger than the first gap, and the second gap is provided with a second region filled with a liquid metal lubricant, and the second region has a surface. The rotating anode type X-ray tube, wherein the rotating portion is located at a position where the mechanical distance to the anode target is shorter than that of the rotating portion facing the first region. 6. An anode target provided in a vacuum container,
A dynamic pressure type slide bearing is provided in a rotating portion penetrating the through hole of the anode target and fixing the anode target to an outer peripheral portion thereof, and in a first region facing the rotating portion with a first gap having a predetermined size. In a rotating anode type X-ray tube comprising a rotating portion and a fixed portion that constitutes a rotating mechanism that rotatably supports the anode target, in the portion surrounded by the through hole of the anode target, the rotating portion and the A rotary anode type X-ray tube, wherein fixed parts face each other with a second gap larger than the first gap and a second region filled with a liquid metal lubricant is provided in the second gap. 7. An anode target provided in a vacuum container,
A first rotation in which a dynamic pressure type slide bearing is provided in a fixed region that constitutes a fixed portion of a rotation mechanism that rotatably supports the anode target, and a first region facing the fixed portion with a first gap of a predetermined size. A rotating anode type X-ray tube having a body and a second rotating body to which the anode target is fixed, and a rotating portion constituting a rotating portion of the rotating mechanism, wherein the first rotating body and the fixed portion are A second region facing the second gap larger than the first gap and having a second region filled with a liquid metal lubricant in the second gap, and the portion of the first rotating body facing the second region, A rotary anode type X-ray tube, wherein the rotary anode type X-ray tube is joined to the second rotary body at a location where the mechanical distance to the anode target is shorter than the portion of the first rotary body facing the first region. . 8. The rotary anode type X-ray tube according to claim 1, wherein the second region is located closer to the center of gravity of the rotating portion than the first region. 9. The rotary anode type X according to claim 1, wherein a spiral groove is formed on at least one surface of the rotating portion and the fixed portion facing the second region.
Line tube. 10. The rotating anode type X-ray according to claim 1, wherein at least one surface of the rotating portion and the fixed portion facing the second region is coated with a high melting point substance. tube. 11. A passage through which a cooling medium flows is formed inside the fixed portion of the second region.
The rotating anode type X-ray tube according to any one of 1.