JP2003217491A - Rotary positive electrode type x-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary positive electrode type X-ray tube preventing leakage of a liquid metal antifriction. <P>SOLUTION: This rotary positive electrode type X-ray tube is provided with: a positive electrode target 13; a rotary support mechanism 14 for rotatably supporting the target 13; radial-direction dynamic pressure type sliding bearings Ra and Rb formed on a fitting surface in the tube axis direction (m); thrust- direction dynamic pressured type sliding bearings Sa and Sb formed on a fitting surface in a direction perpendicular to the tube axis (m); and the liquid metal antifriction fed to the respective parts of the sliding bearings Ra, Rb, Sa and Sb. The X-ray tube is so structured that a recess 19 is formed on the thrust ring 17, protrusions 20 are formed on a fixed body 18, and the thrust ring 17 comes into contact with the fixed body 18 when the rotary part of the support mechanism 14 moves in the tube axial direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rotary anode X-ray tube.

[0002]

2. Description of the Related Art A rotary anode X-ray tube is an electron tube that emits X-rays and has a structure in which an anode target placed in a vacuum container is irradiated with an electron beam to emit X-rays. The anode target is supported by a rotation support mechanism so that it can rotate during X-ray emission. The rotary support mechanism is composed of a rotary portion and a fixed portion that are fitted to each other, and a dynamic pressure type slide bearing, for example, is provided at the fitting portion of both. In the dynamic pressure type slide bearing, a spiral groove is formed on the bearing surface, and a liquid metal lubricant is supplied to the spiral groove portion.

Now, a conventional rotary anode type X-ray tube will be described with reference to a partial sectional view of FIG.

Reference numeral 41 is an anode target that emits X-rays, and the anode target 41 is rotatably supported by a rotation support mechanism 42. The rotation support mechanism 42 is composed of a rotating portion and a fixed portion. The rotating portion includes, for example, a joint portion 43 to which the anode target 41 is connected, a bottomed cylindrical rotor 44 to which the joint portion 43 is connected, and a rotor. 44
Of the thrust ring 45 for sealing the opening at the lower end of the figure.

The fixed portion of the rotation support mechanism 42 is a rotating body 44.
And a cylindrical fixed body 46 and the like fitted inside the thrust ring 45. The fixed body 46 penetrates the opening portion at the center of the thrust ring 45 and extends to the lower side thereof. The lower end 46a of the fixed body 46 is used as a mounting portion for fixing the anode.

Spiral grooves 47a and 47b are formed in pairs at upper and lower portions of the outer peripheral surface of the fixed body 46 to form radial dynamic pressure type sliding bearings Ra and Rb. In addition, the upper end surface of the fixed body 46 in the figure and the thrust ring 45.
A spiral groove (not shown) is formed on the step surface facing
Dynamic pressure type slide bearings Sa and Sb in the thrust direction are formed.

Radial dynamic pressure type sliding bearings Ra, R
b supports a radial load centered on the pipe axis m, and thrust dynamic bearings Sa and Sb support a load in the pipe axis m direction. These dynamic pressure type sliding bearings Ra, R
A liquid metal lubricant is supplied to the portions b, Sa and Sb during operation.

Next, another conventional rotary anode type X-ray tube will be described with reference to a partial sectional view of FIG. In FIG. 5, parts corresponding to those in FIG.

In this example, the anode target 41 and the joint portion 43 are provided with openings, and the upper end 4 of the fixed body 46 is
6b penetrates the joint portion 43 and the anode target 41 and extends above the joint portion 43 and the anode target 41.

[0010]

In the conventional rotary anode type X-ray tube shown in FIG. 4, for example, when the anode target 41 is vertically placed in a vertical position, the rotary portion of the rotary support mechanism 42 descends by its own weight. . At this time, the fitting surface in the region where the dynamic pressure type sliding bearing Sa located above the anode target 41 in the figure is brought into surface contact with the fitting surface where the dynamic pressure type sliding bearing Sb located below the figure is provided. A gap occurs.

In this state, when the clearance between the fitting surfaces provided with the dynamic pressure type slide bearing Sb is narrow, the liquid metal lubricant filled in the bearing portion does not immediately leak out. However, if this state continues for a long time, the liquid metal lubricant may leak from the clearance between the fitting surfaces.

For example, in the exhaust and vacuum heat treatment steps for manufacturing an X-ray tube, when the vertical position with the anode target 41 facing upward continues, the fitting gap of the dynamic pressure type sliding bearing Sb causes a seal gap G. For example, the liquid metal lubricant may leak out through a gap between the fixed body 46 and the thrust ring 45.

When the anode target 41 is vertically placed in a downward posture, since the fitting surface provided with the dynamic pressure type sliding bearing Sa is a closed structure, liquid metal lubricant may leak out. There is no such thing.

However, in the case of the rotary anode type X-ray tube shown in FIG. 5, the fixed body 46 extends in both the upper and lower directions, and the fitting surface provided with the two dynamic pressure type sliding bearings Sa and Sb in the thrust direction is Both are open and not a closed structure. Therefore, there is a problem that the liquid metal lubricant leaks out when the anode target is placed vertically regardless of whether the anode target is above or below.

It is an object of the present invention to solve the above-mentioned drawbacks and to provide a rotary anode type X-ray tube which prevents leakage of a liquid metal lubricant.

[0016]

According to the present invention, there is provided an anode target which emits X-rays, a rotary support mechanism which has a rotating portion and a fixed portion which are fitted to each other, and which rotatably supports the anode target, and Radial dynamic pressure slide bearings formed on the fitting surfaces of the rotating portion and the fixed portion in the pipe axis direction, and a fitting surface formed in the fitting direction of the rotating portion and the fixed portion in a direction orthogonal to the pipe axes. A rotary anode type X equipped with a thrust direction dynamic pressure type slide bearing, and a liquid metal lubricant supplied to each part of the radial direction dynamic pressure type slide bearing and the thrust direction dynamic pressure type slide bearing.
In the wire tube, when the rotating portion relatively moves in the tube axis direction with respect to the fixed portion in a region displaced in the tube axis direction from the fitting surface on which the thrust direction dynamic pressure type slide bearing is formed, It is characterized in that a contact portion that contacts each other is provided in each of the rotating portion and the fixed portion.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to a partial sectional view of FIG. A cathode 12 that generates an electron beam and an anode target 13 that emits X-rays are arranged to face each other in a vacuum chamber 11. The anode target 13 is connected to the rotation support mechanism 14, and the rotation support mechanism 1
It is rotatably supported by 4. Rotation support mechanism 1
Reference numeral 4 denotes a rotating portion and a fixed portion. The rotating portion 4 has, for example, the joint portion 1 to which the anode target 13 is connected.
5 and this joint portion 15 are connected to each other, and are composed of a bottomed cylindrical rotary body 16, a thrust ring 17 for sealing an opening at the lower end of the rotary body 16 in the figure, and the like.

The fixed portion of the rotation support mechanism 14 is composed of, for example, a cylindrical fixed body 18 fitted inside the rotary body 16 and the thrust ring 17. The fixed body 18 penetrates through the central opening portion of the thrust ring 17 and extends further downward, and the lower end 18a thereof is used as a mounting portion for fixing the anode.

Thrust ring 17 through which fixed body 18 penetrates
A concave portion 19 is formed in an annular shape in the inner peripheral portion of the so as to surround the fixed body 18. A convex portion 20 that fits into the concave portion 19 is formed in the fixed body 18 in an annular shape.

Spiral grooves 21a and 21b are formed in a pair at upper and lower portions of the outer peripheral surface of the fixed body 18 to form radial dynamic pressure type sliding bearings Ra and Rb. For example, the upper end surface of the fixed body 18 in the figure and the thrust ring 17
A spiral groove (not shown) is provided on the stepped surface 18b facing to, and dynamic pressure type sliding bearings Sa and Sb in the thrust direction are formed.

Radial dynamic pressure type sliding bearings Ra, R
b supports a radial load centered on the pipe axis m, and thrust dynamic bearings Sa and Sb support a load in the pipe axis m direction. These dynamic pressure type sliding bearings Ra, R
A liquid metal lubricant is supplied to the portions b, Sa and Sb during operation.

Here, the structure of the fitting portion between the concave portion 19 of the thrust ring 17 and the convex portion 20 of the fixed body 18 is shown in FIG.
Will be described with reference to. FIG. 2 is an enlarged view of the fitting portion between the two, showing a gap L1 between the concave portion 19 and the convex portion 20 in the tube axis direction.
Is, for example, a dynamic pressure type sliding bearing Sa, S in the thrust direction.
It is smaller than the interval L2 in the pipe axis m direction between the rotating portion of the region where b is provided, for example, the upper surface 17a of the thrust ring 17 and the step surface 18b of the fixed body 18.

In this case, for example, when the fixed portion is fixed and the rotating portion moves downward in the figure due to its own weight or the like, the concave portions 19 and the convex portions 20 face each other at right angles to the tube axis m.
For example, the downward surface of the concave portion 19 and the upward surface of the convex portion 20 make surface contact in the annular region. At this time, the rotating portion and the fixed portion in the region where the dynamic pressure type slide bearings Sa and Sb are provided are in a non-contact state.

According to the above configuration, the anode target 1
When vertically placed so that 3 is on top, the concave portion 19 of the thrust ring 17 and the convex portion 20 of the fixed body 18 are in surface contact with each other.
Then, the flow of the liquid metal lubricant is stopped at this surface contact portion and leakage is prevented.

The position where the concave portion 19 of the thrust ring 17 and the convex portion 20 of the fixed body 18 are fitted is lower than the dynamic pressure type sliding bearing Sb, for example, from all the dynamic pressure type sliding bearings Ra, Rb, Sa and Sb. Also, a position close to the space inside the vacuum container 11 is desirable.

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 are denoted by the same reference numerals, and overlapping description will be partially omitted.

A through hole 13a is formed in the center of the anode target 13.
Are formed. Further, the rotating portion of the rotary support mechanism 14 that rotatably supports the anode target 13 includes, for example, an outer cylinder 31 to which the anode target 13 is connected and an inner cylinder 32 and an inner cylinder 32 joined to the inside of the outer cylinder 31. The first thrust ring 33 seals the upper opening portion, the second thrust ring 34 seals the lower opening portion of the inner cylinder 32 in the figure, and the like.

The cylindrical fixed body 18 constituting the fixed portion of the rotary support mechanism 14 has its upper end 18c penetrating the first thrust ring 33 and the anode target 13 and extending above it, and its lower end 18a is second. Thrust ring 34
It penetrates through and extends to the bottom.

An annular recess 35 is formed in the inner peripheral portion of the first thrust ring 33 through which the fixed body 18 passes.
The fixed body 18 has an annular projection 3 that fits into the recess 35.
6 is formed. In addition, the second through which the fixed body 18 penetrates
An annular recess 37 is formed in the inner peripheral portion of the thrust ring 34, and an annular protrusion 38 that fits into the recess 37 is formed in the fixed body 18.

In this case, when the anode target 13 is placed vertically with the anode target 13 positioned above, the concave portion 37 and the convex portion 38 positioned below in the figure make surface contact with each other, as in the case of FIG. To be prevented. Further, when the anode target 13 is placed vertically with its lower position, in this case as well, similar to FIG. 1, the concave portions 35 and the convex portions 36 located in the upper portion of the drawing are in surface contact with each other to prevent leakage of the liquid metal lubricant. .

In the above embodiment, the contact surface for preventing leakage of the liquid metal lubricant is orthogonal to the pipe axis. However, the contact surface does not need to be orthogonal to the tube axis, and can be formed as a surface inclined with respect to the tube axis.

Further, in the above embodiment, the contact surface for preventing the leakage of the liquid metal lubricant is located closer to the space in the vacuum container 11 than all the dynamic pressure type slide bearings Ra, Rb, Sa and Sb. It is provided. However, in the case of the structure of FIG. 1 or the like, a contact surface for preventing leakage of the liquid metal lubricant may be provided between, for example, the dynamic pressure type slide bearing Rb and the dynamic pressure type slide bearing Sb. In this case, the contact surface seals the liquid metal lubricant located above it. As a result, the load of the liquid metal lubricant applied to the dynamic pressure type slide bearing Sb and the seal gap, that is, the gap in the portion where the fixed body 18 penetrates the thrust ring 17 is reduced, and the leakage prevention effect is obtained.

Further, in the above-mentioned embodiment, the contact portions of the rotating portion and the fixed portion which come into contact with each other are planar. However, for example, one of the contact portions of the rotating portion and the fixed portion may be linear.

[0034]

According to the present invention, it is possible to realize a rotary anode type X-ray tube in which the liquid metal lubricant is prevented from leaking.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view for explaining an embodiment of the present invention.

FIG. 2 is an enlarged view for explaining a contact surface structure for preventing leakage of the liquid metal lubricant used in the embodiment of the present invention.

FIG. 3 is a partial cross-sectional view for explaining another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view for explaining a conventional example.

FIG. 5 is a partial cross-sectional view for explaining another conventional example.

[Explanation of symbols]

11 ... Vacuum container 12 ... Cathode 13 ... Anode target 14 ... Rotation support mechanism 15 ... Joint 16 ... Rotating body 17 ... Thrust ring 18 ... Fixed body 19 ... Recess 20 ... Projection 21a, 21b ... spiral groove Ra, Rb ... radial dynamic bearings Sa, Sb ... Dynamic pressure type sliding bearing in thrust direction m ... tube axis

Claims (4)

[Claims] 1. A rotary support mechanism that has an anode target that emits X-rays, a rotating portion and a fixed portion that are fitted to each other, and that rotatably supports the anode target, and tubes of the rotating portion and the fixed portion. A radial dynamic pressure type slide bearing formed on the axial fitting surface, and a thrust direction dynamic pressure type slide bearing formed on the fitting surface orthogonal to the pipe axes of the rotating portion and the fixed portion, In a rotary anode type X-ray tube provided with the radial direction dynamic pressure type slide bearing and the liquid metal lubricant supplied to each part of the thrust direction dynamic pressure type slide bearing, the thrust direction dynamic pressure type slide bearing is formed. A contact portion that comes into contact with each other when the rotating portion relatively moves in the pipe axis direction with respect to the fixed portion, in a region displaced from the fitted surface in the pipe axis direction; A rotary anode type X-ray tube provided on each of the minute portion and the fixed portion. 2. The rotating anode type X-ray tube according to claim 1, wherein the contact portions for contacting the rotating portion and the fixed portion are provided at two positions apart from each other in the tube axial direction. 3. The contact portion where the rotating portion and the fixed portion come into contact is provided at a position closer to the space in the vacuum container than the region where the dynamic pressure type slide bearings in the radial direction and the thrust direction are provided. Item 2. A rotating anode X-ray tube according to item 2. 4. The distance between the contact portion of the rotating portion and the contact portion of the fixed portion in the pipe axial direction is determined by a pipe between the rotating portion and the fixed portion in a fitting region in which a thrust type dynamic pressure type slide bearing is formed. The rotating anode type X-ray tube according to any one of claims 1 to 3, which is smaller than the axial distance.