JP3811077B2 - Rotating anode X-ray tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary anode X-ray tube.
[0002]
[Prior art]
The rotary anode X-ray tube is an electron tube that emits X-rays, and has a structure in which an anode target disposed in a vacuum vessel is irradiated with an electron beam and X-rays are emitted from the anode target. The anode target is supported by a rotation support mechanism so that it can be rotated when X-rays are emitted. The rotation support mechanism is composed of a rotating portion and a fixed portion that are fitted together, and a hydrodynamic slide bearing is provided at the fitting portion of both. In the hydrodynamic slide bearing, a spiral groove is formed on the bearing surface, and a liquid metal lubricant is supplied to the spiral groove portion.
[0003]
Here, a conventional rotary anode X-ray tube will be described with reference to a partial sectional view of FIG.
[0004]
Reference numeral 41 denotes an anode target that emits X-rays. The anode target 41 is rotatably supported by a rotation support mechanism 42. The rotation support mechanism 42 includes 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 rotating body 44 to which the joint portion 43 is connected, and a rotating body. The thrust ring 45 is configured to seal the opening at the lower end of the figure 44.
[0005]
The fixed portion of the rotation support mechanism 42 includes a rotating body 44 and a columnar fixing body 46 fitted inside the thrust ring 45. The fixed body 46 extends through the opening portion in the center of the thrust ring 45 to the lower side. The lower end 46a of the fixed body 46 is used as an attachment portion for fixing the anode.
[0006]
In addition, spiral grooves 47a and 47b are formed in pairs at two locations on the upper and lower sides of the outer peripheral surface of the fixed body 46, and dynamic pressure type sliding bearings Ra and Rb in the radial direction are formed. In addition, a spiral groove (not shown) is formed on the upper end surface of the fixed body 46 shown in the figure and a step surface facing the thrust ring 45, and dynamic pressure type sliding bearings Sa and Sb in the thrust direction are formed.
[0007]
The radial dynamic pressure bearings Ra and Rb support a radial load centered on the tube axis m, and the thrust dynamic pressure bearings Sa and Sb support a load in the tube axis m direction. During operation, liquid metal lubricant is supplied to these hydrodynamic slide bearings Ra, Rb, Sa, Sb.
[0008]
Next, another conventional rotary anode X-ray tube will be described with reference to a partial cross-sectional view of FIG. In FIG. 5, parts corresponding to those in FIG.
[0009]
In the case of this example, the anode target 41 and the joint portion 43 are provided with openings, and the upper end 46b of the fixed body 46 extends through the joint portion 43 and the anode target 41 to the upper side.
[0010]
[Problems to be solved by the invention]
For example, when the conventional rotary anode X-ray tube shown in FIG. 4 is placed vertically with the anode target 41 facing upward, the rotating portion of the rotary support mechanism 42 is lowered by its own weight. At this time, the fitting surface in the region provided with the dynamic pressure type sliding bearing Sa located in the upper part of the figure near the anode target 41 is in surface contact with the fitting surface provided with the dynamic pressure type sliding bearing Sb located in the lower part of the figure. A gap occurs.
[0011]
In this state, when the gap between the fitting surfaces provided with the hydrodynamic slide bearing Sb is narrow, the liquid metal lubricant filled in the bearing portion does not leak immediately. However, if this state continues for a long time, the liquid metal lubricant may leak from the gap between the fitting surfaces.
[0012]
For example, if the vertical posture with the anode target 41 on continues in the exhaust and vacuum heat treatment process for manufacturing the X-ray tube, the seal gap G, for example, a fixed body is inserted from the fitting gap of the hydrodynamic slide bearing Sb portion. In some cases, the liquid metal lubricant leaks through a gap in a portion where 46 penetrates the thrust ring 45.
[0013]
Note that when the anode target 41 is placed vertically with the posture downward, the fitting surface provided with the hydrodynamic slide bearing Sa has a sealed structure, so that the liquid metal lubricant does not leak out. .
[0014]
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 surfaces provided with the two dynamic pressure type slide bearings Sa and Sb in the thrust direction are both open. The structure is not sealed. Therefore, even when the anode target is on the upper side or the lower side, there is a problem in that the liquid metal lubricant leaks when it is placed vertically.
[0015]
An object of the present invention is to provide a rotary anode type X-ray tube that solves the above-described drawbacks and prevents leakage of a liquid metal lubricant.
[0016]
[Means for Solving the Problems]
The present invention includes an anode target that is disposed in a vacuum vessel and emits X-rays, a rotating part and a fixing part that are fitted to each other, a rotation support mechanism that rotatably supports the anode target, the rotating part, A radial hydrodynamic slide bearing formed on the fitting surface of the fixed portion in the tube axis direction, and a thrust direction movement formed on the fitting surface in a direction perpendicular to the rotating portion and the tube axis of the fixed portion. A rotary anode X-ray tube comprising: a pressure type slide bearing; and a liquid metal lubricant supplied to each of the radial direction dynamic pressure type slide bearing and the thrust direction dynamic pressure type slide bearing. moving from the mating surface pressure sliding bearing is formed in a region close to the space in the vacuum vessel displaced in the axial direction of the tube, the rotating portion relative tube axis direction with respect to the fixed part The contact portion mutual contacts when the, characterized in that provided on each of said rotating portion and the fixed portion.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to a partial cross-sectional view of FIG. A cathode 12 for generating an electron beam and an anode target 13 for emitting X-rays are disposed in the vacuum container 11 so as to face each other. The anode target 13 is connected to the rotation support mechanism 14 and is rotatably supported by the rotation support mechanism 14. The rotation support mechanism 14 includes a rotating portion and a fixed portion. The rotating portion includes, for example, a joint portion 15 to which the anode target 13 is connected, a bottomed cylindrical rotating body 16 to which the joint portion 15 is connected, and this rotation. The thrust ring 17 is configured to seal the opening at the lower end of the body 16 in the figure.
[0018]
The fixed portion of the rotation support mechanism 14 includes, for example, a columnar fixed body 18 that fits inside the rotary body 16 and the thrust ring 17. The fixed body 18 passes through the opening at the center of the thrust ring 17 and extends further downward, and its lower end 18a is used as a mounting portion for fixing the anode.
[0019]
A concave portion 19 that surrounds the fixed body 18 is formed in an annular shape on the inner peripheral portion of the thrust ring 17 through which the fixed body 18 passes. On the fixed body 18, a convex portion 20 that fits into the concave portion 19 is formed in an annular shape.
[0020]
In addition, spiral grooves 21a and 21b are formed in pairs at two locations on the upper and lower sides of the outer peripheral surface of the fixed body 18 to form radial hydrodynamic slide bearings Ra and Rb. For example, spiral grooves (not shown) are provided on the upper end surface of the fixed body 18 and the step surface 18b facing the thrust ring 17, and dynamic pressure type sliding bearings Sa and Sb in the thrust direction are formed.
[0021]
The radial dynamic pressure bearings Ra and Rb support a radial load centered on the tube axis m, and the thrust dynamic pressure bearings Sa and Sb support a load in the tube axis m direction. During operation, liquid metal lubricant is supplied to these hydrodynamic slide bearings Ra, Rb, Sa, Sb.
[0022]
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 will be described with reference to FIG. FIG. 2 is an enlarged view of the fitting portion between them, and the interval L1 in the tube axis direction between the concave portion 19 and the convex portion 20 is, for example, a rotating portion in the region where the dynamic pressure type sliding bearings Sa and Sb in the thrust direction are provided. The distance L2 between the upper surface 17a of the ring 17 and the stepped surface 18b of the fixed body 18 in the tube axis m direction is smaller.
[0023]
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 surfaces perpendicular to the tube axis m of the concave portion 19 and the convex portion 20, for example, the downward surface and convex portion of the concave portion 19 The upward surface of the portion 20 is in surface contact with the annular region. At this time, the rotating portion and the fixed portion in the region where the hydrodynamic slide bearings Sa and Sb are provided are in a non-contact state.
[0024]
According to the configuration described above, when the anode target 13 is placed vertically so that the anode target 13 faces upward, the concave portion 19 of the thrust ring 17 and the convex portion 20 of the fixed body 18 are in surface contact. Then, the flow of the liquid metal lubricant stops at this surface contact portion, and leakage is prevented.
[0025]
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, the vacuum container than all the dynamic pressure type sliding bearings Ra, Rb, Sa, Sb. A position close to the space in 11 is desirable.
[0026]
Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 3, parts corresponding to those in FIG.
[0027]
A through hole 13 a is formed in the center of the anode target 13. The rotating portion of the rotation 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, an inner cylinder 32 that is joined to the inner side of the outer cylinder 31, and an inner cylinder 32 illustrated in the figure. 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.
[0028]
Further, the cylindrical fixed body 18 constituting the fixed portion of the rotation support mechanism 14 has an upper end 18c extending through the first thrust ring 33 and the anode target 13, and a lower end 18a extending to the second thrust ring 34. It extends through to the bottom.
[0029]
An annular recess 35 is formed in the inner peripheral portion of the first thrust ring 33 through which the fixed body 18 passes, and the annular protrusion 36 that fits into the recess 35 is formed in the fixed body 18. Further, an annular recess 37 is formed in the inner peripheral portion of the second thrust ring 34 through which the fixed body 18 passes, and the annular protrusion 38 that fits into the recess 37 is formed in the fixed body 18.
[0030]
In this case, when the anode target 13 is placed vertically, as in FIG. 1, the concave portion 37 and the convex portion 38 located in the lower part of the figure are in surface contact with each other, and leakage of the liquid metal lubricant is prevented. . In addition, when the anode target 13 is placed vertically, the concave portion 35 and the convex portion 36 located in the upper part of the figure are in surface contact with each other to prevent leakage of the liquid metal lubricant, as in FIG. .
[0031]
In the above embodiment, the contact surface for preventing leakage of the liquid metal lubricant is orthogonal to the tube 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.
[0032]
Further, in the above embodiment, the contact surface for preventing the leakage of the liquid metal lubricant is provided at a position closer to the space in the vacuum vessel 11 than all of the dynamic pressure type slide bearings Ra, Rb, Sa, Sb. . However, in the case of the structure of FIG. 1 and the like, a contact surface for preventing leakage of the liquid metal lubricant can be provided, for example, between the hydrodynamic slide bearing Rb and the hydrodynamic slide bearing Sb. In this case, the liquid metal lubricant positioned above the contact surface is sealed. As a result, the load of the liquid metal lubricant applied to the hydrodynamic slide bearing Sb and the seal gap, that is, the gap where the fixed body 18 penetrates the thrust ring 17 is reduced, and the leakage preventing effect is obtained.
[0033]
Moreover, in said embodiment, the contact part which mutually contacts a rotation part and a fixed part is planar. However, for example, one of the contact portions of the rotating portion and the fixed portion can be configured linearly.
[0034]
【The invention's effect】
According to the present invention, it is possible to realize a rotary anode type X-ray tube that prevents the liquid metal lubricant from leaking.
[Brief description of the 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 a liquid metal lubricant used in an 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]
DESCRIPTION OF SYMBOLS 11 ... Vacuum container 12 ... Cathode 13 ... Anode target 14 ... Rotation support mechanism 15 ... Joint part 16 ... Rotating body 17 ... Thrust ring 18 ... Fixed body 19 ... Concave part 20 ... Convex part 21a, 21b ... Spiral groove Ra, Rb ... Radial Direction dynamic pressure type slide bearings Sa, Sb ... thrust direction dynamic pressure type slide bearings m ... pipe shaft

Claims (4)

An anode target that is arranged in a vacuum vessel and emits X-rays, a rotating part and a fixed part that fit together, a rotation support mechanism that rotatably supports the anode target, and the rotating part and the fixed part A radial dynamic pressure type slide bearing formed on the fitting surface in the tube axis direction, and a dynamic pressure type slide bearing in the thrust direction formed on the fitting surface perpendicular to the tube axis of the rotating part and the fixed part; In the rotary anode type X-ray tube comprising the liquid dynamic lubricant supplied to each part of the radial dynamic pressure slide bearing and the thrust dynamic pressure slide bearing, the thrust dynamic pressure slide bearing comprises: in the region close to the space displaced from the formed mating surfaces in the axial direction of the tube the vacuum container, when the rotary part relative to the fixed part is moved relative tube axis direction The contact portion for Iga contact, the rotating portion and the rotating anode X-ray tube, characterized in that provided on each of said fixed part.   2. The rotating anode type X-ray tube according to claim 1, wherein contact portions where the rotating portion and the fixed portion are in contact are provided at two locations separated in the tube axis direction.   The rotation portion according to claim 1 or 2, wherein the contact portion where the rotating portion and the fixed portion are in contact is provided at a position closer to the space in the vacuum vessel than the region in which the dynamic pressure type plain bearings in the radial direction and the thrust direction are provided. Anode X-ray tube.   The distance in the tube axis direction between the contact portion of the rotating portion and the contact portion of the fixed portion is based on the distance in the tube axis direction between the rotating portion and the fixed portion in the fitting region where the dynamic pressure type plain bearing in the thrust direction is formed. The rotary anode type X-ray tube according to any one of claims 1 to 3, wherein the rotary anode type X-ray tube is smaller.

Images