JP4153829B2 - 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]
A rotating anode type X-ray tube is composed of an anode target that emits X-rays, a cathode that generates an electron beam, a rotating support mechanism that rotatably supports the anode target, and the anode target, the cathode, and the rotating support mechanism are outside the vacuum. It is stored in the enclosure.
[0003]
Here, a conventional rotary anode X-ray tube will be described with reference to FIG.
[0004]
The anode target 51 that emits X-rays is disposed in a vacuum envelope (not shown) together with a cathode and the like. The anode target 51 is fixed to a joint portion 53 with a nut 52, and the joint portion 53 is connected to a rotation support mechanism 54. The rotation support mechanism 54 includes a rotating part and a fixed part.
[0005]
The rotating portion includes an intermediate rotating body 55 directly connected to the joint portion 53, an outer rotating body 56 joined to the outside of the intermediate rotating body 55, an inner rotating body 57 joined to the inside of the intermediate rotating body 55, and the like. The opening at the lower end of the inner rotating body 57 is sealed with a ring-shaped closing body 58.
[0006]
The closing body 58 includes a thick inner closing portion 58a and a thin outer closing portion 58b. An annular capturing member 59 for preventing leakage of the liquid metal lubricant is provided below the closing body 58. The closing body 58 and the capturing member 59 are fixed to the inner rotating body 57 by a common bolt 60 oriented in parallel to the tube axis m. A fixed body 61 constituting a fixed portion of the rotation support mechanism 54 is fitted into the inner space surrounded by the inner rotary body 27 and the closing body 58.
[0007]
The fixed body 61 is fitted into the first small diameter portion 61a fitted to the inner rotary body 57 portion, the large diameter portion 61b fitted to the lower inner rotary body 57 portion, and the through hole portion of the closing body 58. It consists of a two-diameter small portion 61c and the like. The second small diameter portion 61 c passes through the through hole, and its extended lower end 61 d is connected to the anode support portion 62.
[0008]
A hydrodynamic slide bearing (not shown) between the rotating portion and the fixed portion constituting the rotation support mechanism 54, for example, between the inner rotating body 57 or the closing body 58 of the rotating portion and the fixed body 61 of the fixed portion. Is provided.
[0009]
A stator 63 that generates an induction electromagnetic field is disposed so as to surround the rotation support mechanism 54, for example, the outer rotating body 56. The stator 63 includes a coil 63a and an iron core 63b.
[0010]
In the configuration described above, an electric current is passed through the coil 63a to generate an induction electromagnetic field, and the outer rotating body 56 is rotated. The anode target 51 is rotated by the rotation of the outer rotating body 56. In this state, the anode target 51 is irradiated with an electron beam, and the anode target 51 emits X-rays.
[0011]
A rotary anode type X-ray tube using a dynamic pressure type plain bearing as described above is disclosed in Patent Document 1 and the like.
[0012]
[Patent Document 1]
Japanese Patent Publication No. 60-21463 [0013]
[Problems to be solved by the invention]
The conventional rotary anode X-ray tube is required to have good rotation characteristics such as an improvement in rotational force with respect to the anode target 51 or stability of rotation.
[0014]
For example, when the anode target 51 is rotated, an induction electromagnetic field generated by the coil 62a is applied to the outer rotating body 56, and the outer rotating body 56 is rotated. In this case, in order to efficiently supply the induction electromagnetic field to the outer rotating body 56, the length of the cylindrical portion of the outer rotating body 56 that protrudes in the axial direction from the iron core 62 b portion, for example, the so-called end ring (for example, It is necessary to ensure sufficient L) in FIG.
[0015]
However, the conventional rotary anode X-ray tube has a structure in which a female screw portion in the tube axis direction is provided at the lower end portion of the inner rotary body 57 and the closing body 58 is fixed with a bolt 60. In this case, since it is necessary to secure a space for forming the female screw portion, the enormous portion 57 a bulging outward is provided at the lower end portion of the inner rotating body 57. Therefore, the enormous part 57a obstructs, the length of the end ring is restricted, and the rotational force of the anode target 51 is reduced.
[0016]
Further, in order to stabilize the rotation of the anode target 51, it is required to increase the bearing area of a hydrodynamic slide bearing provided between the rotating body closing body 58 and the fixed body 61, for example, a thrust bearing, to ensure load characteristics. It is done.
[0017]
In the case of the configuration of FIG. 4, the area of the thrust bearing is determined by, for example, the size of the area where the lower surface of the large diameter portion 61 b of the fixed body 61 and the closing body 58 face each other. That is, it is determined by the area of the region sandwiched between the first circle formed by the outer diameter of the large-diameter portion 61b and the second circle formed by the outer diameter of the small-diameter portion 61c penetrating the closing body 58.
[0018]
In this case, since the closing body 58 is fixed to the inner rotating body 57, it is necessary to attach a bolt to the closing body 58. Generally, the outermost diameter of the closing body 58 is larger than the outer diameter of the large diameter portion 61b. Become. Further, when the outermost diameter of the closing body 58 is increased, the X-ray tube is increased in size, so that there is an upper limit value for the size of the closing body 58 and the outer diameter of the large diameter portion 58 cannot be increased too much. On the other hand, the outer diameter of the small-diameter portion 61c needs a certain size in order to ensure sufficient support strength and cannot be made too small.
[0019]
For the reasons described above, there is a problem that the area of the thrust bearing surface cannot be increased, the load characteristics of the bearing are lowered, and the rotational stability cannot be improved.
[0020]
An object of the present invention is to provide a rotary anode type X-ray tube that solves the above-mentioned drawbacks, improves the rotational force of the anode target, or improves the load characteristics of the bearing and has good rotational characteristics. .
[0021]
[Means for Solving the Problems]
The present invention includes an anode target that emits X-rays, an intermediate rotating body that is connected to a joint portion to which the anode target is fixed, an outer rotating body that is joined to the outside of the intermediate rotating body, and an inner side of the intermediate rotating body. An inner rotating body that is joined and does not bulge outward to hinder the extension of the lower end of the outer rotating body, and the inner opening of the cylindrical portion is sealed with a ring-shaped closing body, and is integrated with the anode target. The rotating body has a large-diameter portion with a large outer diameter that fits into the inner portion of the rotating body, and a small-diameter portion that has a smaller outer diameter than the large-diameter portion and fits into the through-hole portion of the closing body. And a rotating anode type X-ray tube comprising a fixed body for rotatably holding the rotating body, wherein a plurality of internal thread portions facing a tube axis are formed in the cylindrical portion of the rotating body , and the closure The outer diameter of the anode target side is large on the outer peripheral surface of the body. An inclined surface is formed, characterized in that the tip is attached to the plurality of female screw portion is fixed to the closure member by contact with the screw on the inclined surface of the closure.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG.
[0023]
The anode target 11 that emits X-rays is disposed in a vacuum envelope (not shown) together with a cathode that generates an electron beam. The anode target 11 is fixed to a joint portion 13 by a nut 12, and the joint portion 13 is connected to a rotation support mechanism 14. The rotation support mechanism 14 includes a rotating portion and a fixed portion, and the rotating portion is rotatably held by the fixed portion.
[0024]
The rotating portion includes an intermediate rotating body 15 directly connected to the joint 13, a cylindrical outer rotating body 16 made of copper or a copper alloy bonded to the outside of the intermediate rotating body 15, and a bottomed structure bonded to the inside of the intermediate rotating body 15. It is comprised from the cylindrical inner side rotary body 17 grade | etc.,.
[0025]
The inner rotating body 17 has a first step surface 17a and a second step surface 17b formed in an annular shape on the inner peripheral surface. In each step surface 17a, 17b, the inner diameter far from the anode target 11 is large. The lower end of the inner rotating body 17 has a cylindrical shape, and a plurality of, for example, about eight internal thread portions 18 are provided at equal intervals in the circumferential direction on the cylindrical portion 17c.
[0026]
The female thread portion 18 is formed, for example, in a direction facing the tube axis m and perpendicular to the tube axis m. For example, a push screw 19 is attached to the female screw portion 18. The push screw 19 has a structure in which a head portion, for example, a portion having a diameter larger than that of the screw portion is not provided at the end portion. A ring-shaped closing body 20 is disposed inside the lower end of the inner rotating body 17 and its opening is sealed.
[0027]
The closing body 20 is composed of, for example, a thick inner closing portion 20a and a thin outer closing portion 20b, and a stepped surface 20c facing the anode target 11 is provided in an annular shape on the outer peripheral surface thereof. . The step surface 20 c is in surface contact with the second step surface 17 b of the inner rotating body 17. Further, on the outer peripheral surface of the closing body 20, for example, an inclined surface 20 d whose outer diameter becomes smaller as it gets away from the anode target 11 is formed in an annular shape in a region farther from the anode target 11 than the step surface 20 c. And the front-end | tip of the some press screw 19 is pressed against the inclined surface 20d, and the obstruction | occlusion body 20 is being fixed.
[0028]
For example, when each push screw 19 is tightened, the tip of the push screw 19 comes into contact with the inclined surface of the closing body 20 and an inward force is applied to the closing body 20. At this time, since the tip of the push screw 19 comes into contact with the inclined surface 20d of the closing body 20, a force that moves upward in the figure acts on the closing body 20. With this force, the stepped surface 20c of the closing body 20 and the second stepped surface 17b of the inner rotating body 17 come into strong surface contact, and further movement of the closing body 20 is prevented, and the closing body 20 is fixed. In addition, a fixed body 21 constituting the rotation support mechanism 14 is fitted in an inner space surrounded by the inner rotating body 17 and the closing body 20 while maintaining a bearing gap.
[0029]
The fixed body 21 is fitted into, for example, the first small diameter portion 21a fitted to the inner rotary body 17 portion, the large diameter portion 21b fitted to the lower inner rotary body 17 portion, and the through hole portion of the closing body 20. The second small diameter portion 21c is configured. The second small diameter portion 21 c extends downward through the closing body 20, and the extended lower end portion 21 d is connected to the anode support portion 22. Further, a capture member 23 for preventing leakage of the liquid metal lubricant is fixed to the anode support portion 22.
[0030]
In a state where the closing body 20 is fixed with the push screw 19 or the like, for example, a slight gap remains between the lower surface of the large diameter portion 21b and the upper surface of the inner closing body 20a, and the dimensions are such that they do not adhere to each other. .
[0031]
Further, for example, a hydrodynamic slide bearing is provided between the inner rotating body 17 or the closing body 20 constituting the rotating portion of the rotation support mechanism 14 and the fixed body 21 constituting the fixed portion. Symbols Ra and Rb indicate regions where the radial dynamic pressure type slide bearings are provided, and symbols Sa and Sb indicate regions where the thrust direction dynamic pressure type slide bearings are provided. A hydrodynamic slide bearing forms a spiral groove on a bearing surface, and a liquid metal lubricant such as gallium (Ga) or a gallium-indium-tin (Ga-In-Sn) alloy is supplied to the spiral groove.
[0032]
A stator 24 that generates an induction electromagnetic field is disposed outside the rotation support mechanism 14, for example, surrounding the outer rotating body 16. The stator 24 includes a coil 24a and an iron core 24b.
[0033]
In the configuration described above, an electric current is passed through the coil 24a to generate an induction electromagnetic field, and the outer rotating body 16 is rotated. Due to the rotation of the outer rotating body 16, the intermediate rotating body 15 and the inner rotating body 17 integrated therewith rotate, and at the same time, the anode target 11 rotates. In this state, the anode target 11 is irradiated with an electron beam, and the anode target 11 emits X-rays.
[0034]
According to the configuration described above, the closing body 20 is fixed by the push screw 19 facing the tube axis m. In this case, there is no bulge in the outside of the inner rotating member 17 the lower end, you can lengthen the extension e.g. et Ndoringu outer rotating member 16 the lower end. As a result, the rotational force is improved and good rotational characteristics are realized.
[0035]
In the above-described embodiment, the female screw portion 18 of the inner rotating body 17 is positioned below the lower end of the outer rotating body 16, and the screw is tightened from below the outer rotating body 16. However, if the lower end of the outer rotating body 16 is extended below the female thread portion 18 and a hole is provided in the extended portion, and the screw is tightened through this hole, the end ring can be made longer.
[0036]
Further, in the embodiment, the female thread portion 18 is formed in a direction facing the tube axis m and in a direction orthogonal to the tube axis m. However, the direction of the female screw portion 18 does not necessarily need to be orthogonal to the tube axis m. For example, the direction of the female screw portion 18 may be formed in a direction inclined toward the tube axis m and inclined with respect to the tube axis m. Also, other screws can be used instead of the push screws. However, when a push screw is used, the portion that protrudes outward from the outer peripheral surface of the inner rotating body 17 is eliminated, and the end ring can be easily extended.
[0037]
Another embodiment of the present invention will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG.
[0038]
In this embodiment, a female thread portion 31 is formed on the inner peripheral surface of the cylindrical portion 17 c located at the lower end of the inner rotating body 17. The closing body 20 has a male thread portion 32 formed on the outer peripheral surface. In addition, a recess, for example, a plurality of cylindrical holes 33 for fastening, are formed in the surface of the closing body 20 on the side opposite to the anode target 11. Further, at least a part of the lower end of the cylindrical portion 17c of the inner rotating body 17 and the outer edge portion of the closing body 20 adjacent to the lower end portion are welded 34.
[0039]
With the above structure, a jig (not shown) is inserted into the hole 33 of the closing body 20, and then the male screw portion of the closing body 20 is screwed into the female thread portion 31 of the inner rotating body 17 using the jig. The closing body 20 is fixed to the inner rotating body 17.
[0040]
According to the above-described configuration, the screw hole for fixing the closing body 20 that has been conventionally required for the inner rotating body 17 becomes unnecessary, and the inner rotating body 17 does not bulge outward. Therefore, an extension example et Ndoringu outer rotating member 16 the lower end can be long, the rotational force is improved, good rotation characteristics can be realized. Further, since the inner rotating body 17 and the closing body 20 are partially welded, loosening of the coupling between the two is prevented.
[0041]
Another embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same reference numerals are given to portions corresponding to FIG. 2, and a part of overlapping description is omitted.
[0042]
In this embodiment, a huge portion 41 that swells in an annular shape is formed outside the lower end of the inner rotating body 17 . And the outer diameter of the large diameter part 21b of the fixed body 21 is enlarged using the enormous part 41. FIG.
[0043]
According to the configuration described above, the area where the upper surface of the large-diameter portion 21b of the fixed body 21 and the inner rotary body 17 face each other without increasing the outermost diameter of the inner rotary body 17 as compared with the conventional rotary anode X-ray tube. And the area which the large diameter part 21b lower surface of the fixed body 21 and the closure body 20 oppose becomes large. Therefore, the area of the thrust bearing surface can be increased, the load characteristics of the bearing are improved, and good rotation characteristics are realized.
[0044]
In FIG. 3, a huge portion 41 is provided at the lower end of the inner rotating body 17 . However, even if there is no expanded portion 41, compared to the structure of the conventional inner rotating body 17 provided with a female screw portion 31, can be increased outermost diameter of the inner rotating member 17, good rotation characteristics can be realized.
[0045]
As described above, according to the present invention, the end ring of the outer rotating body can be lengthened, and the rotational force of the anode target is improved. In addition, a rotating anode X-ray tube having good rotational characteristics, such as an improvement in bearing load characteristics due to an increase in bearing area, is realized. In addition, miniaturization of the rotary anode type X-ray tube is realized.
[0046]
【The invention's effect】
According to the present invention, a rotary anode type X-ray tube having good rotational characteristics can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view for explaining an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view for explaining another embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view for explaining another embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view for explaining a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Anode target 12 ... Nut 13 ... Joint part 14 ... Rotation support mechanism 15 ... Intermediate | middle rotary body 16 ... Outer rotary body 17 ... Inner rotary body 18 ... Female thread part 19 ... Set screw 20 ... Closure body 21 ... Fixed body 21
22 ... Anode support 23 ... Capture member 24 ... Stator m ... Tube shaft

Claims (2)

An anode target that emits X-rays, an intermediate rotating body that is connected to a joint portion to which the anode target is fixed, an outer rotating body that is bonded to the outside of the intermediate rotating body, and an outer surface that is bonded to the inner side of the intermediate rotating body A rotating body that has an inner rotating body that does not bulge to the outside and obstructs the extension of the lower end of the rotating body, and the inner opening of the cylindrical portion is sealed with a ring-shaped closing body, and rotates integrally with the anode target A large-diameter portion having a large outer diameter that fits into the inner portion of the rotating body, and a small-diameter portion that has a smaller outer diameter than the large-diameter portion and fits into the through-hole portion of the closing body, and In a rotary anode X-ray tube comprising a fixed body that rotatably holds a body, a plurality of internal thread portions facing a tube axis are formed in the cylindrical portion of the rotating body, and an outer peripheral surface of the closing body Form an inclined surface with a larger outer diameter on the anode target side And, rotating anode X-ray tube, characterized in that the tip is attached to the plurality of female screw portion is fixed to the closure member by screws in contact with the inclined surface of the closure. A first step surface having a smaller outer diameter on the anode target side is formed on the outer peripheral surface of the closing body closer to the anode target than the inclined surface with which the tip of the screw contacts , and the first step surface is formed on the inner peripheral surface of the rotating body. The rotary anode type X-ray tube according to claim 1, wherein a second step surface is provided in contact with the step surface .

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