JP2015060693A - Rotating anode x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating anode X-ray tube in which peeling between the components due to difference of coefficient of thermal expansion is prevented.SOLUTION: A rotating anode X-ray tube includes a fixed shaft, a first fixed cylinder, and a second fixed cylinder. The fixed shaft has a hollow shape for supporting an anode target rotatably. The first fixed cylinder and second fixed cylinder are inserted into the fixed shaft, respectively, from the openings on both sides thereof and bonded to the fixed shaft. The bonding surface of the fixed shaft, and the first and second fixed cylinders includes a surface intersecting the axial direction of the fixed shaft.

Description

  Embodiments described herein relate generally to a rotary anode X-ray tube.

  In general, a rotary anode type X-ray tube device is used as the X-ray tube device. A rotary anode type X-ray tube device includes a rotary anode type X-ray tube that emits X-rays, a stator coil, and a housing that houses the rotary anode type X-ray tube and the stator coil. The rotating anode type X-ray tube includes a fixed shaft, a rotating body, a cathode, and a vacuum envelope. The rotating body includes an anode target.

  In this rotary anode type X-ray tube, the stator coil generates a magnetic field, whereby the rotating body rotates around the fixed axis. When the cathode irradiates the anode target with electrons while the rotating body is rotating, the anode target generates X-rays in response to the collision of the electrons.

Japanese Patent Publication No. 6-70896 JP 2012-104391 A JP 2011-60517 A JP 2010-257649 A

  For example, the fixed shaft of the rotary anode X-ray tube has a hollow shape with both ends opened. In this case, a configuration is adopted in which the first fixed cylinder and the second fixed cylinder are respectively inserted into the fixed shaft from both ends and the outer walls of the first fixed cylinder and the second fixed cylinder are joined to the inner wall of the fixed shaft. Sometimes. The fixed shaft, the first fixed cylinder, and the second fixed cylinder are joined by, for example, brazing.

  When the material of the fixed shaft is different from the material of the first fixed cylinder and the second fixed cylinder, due to the difference in the coefficient of thermal expansion of each material, the fixed shaft, the first fixed cylinder, and the second fixed cylinder according to the temperature change. The degree of expansion or contraction is different. Therefore, there is a possibility that peeling occurs at the joint surface between the fixed shaft and the first fixed cylinder and the second fixed cylinder. For example, when the fixed shaft is formed of a molybdenum alloy and the first fixed cylinder and the second fixed cylinder are formed of an iron alloy or stainless steel, the thermal expansion coefficient of the molybdenum alloy and the iron alloy or stainless steel is different from about twice, Peeling easily occurs.

  Since the outside of the fixed shaft is a vacuum and the inside of the fixed shaft is filled with a cooling liquid or communicates with the outside air, the vacuum in the X-ray tube cannot be maintained when the above-described peeling occurs. If it does so, the withstand voltage defect of an X-ray tube will arise and it will become impossible to maintain the performance of an X-ray tube.

  The problem to be solved by the present invention is to provide a rotating anode type X-ray tube that prevents separation between components due to a difference in thermal expansion coefficient.

  The rotary anode X-ray tube in one embodiment includes a fixed shaft, a first fixed cylinder, and a second fixed cylinder. The fixed shaft has a hollow shape that rotatably supports the anode target. The first fixed cylinder and the second fixed cylinder are inserted into the fixed shaft from the openings on both sides, and are joined to the fixed shaft. A joint surface between the fixed shaft, the first fixed cylinder, and the second fixed cylinder includes a surface that intersects the axial direction of the fixed shaft.

It is sectional drawing which shows a part of component of the rotating anode type | mold X-ray tube which concerns on 1st Embodiment. It is a figure for demonstrating the joining method of the fixed axis | shaft in the same embodiment, a 1st fixed cylinder, and a 2nd fixed cylinder. It is a figure for demonstrating the joining method of the fixed axis | shaft in a 2nd Embodiment, a 1st fixed cylinder, and a 2nd fixed cylinder. It is a figure for demonstrating the joining method of the fixed axis | shaft in a 3rd Embodiment, a 1st fixed cylinder, and a 2nd fixed cylinder.

Several embodiments will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a part of elements constituting the rotary anode X-ray tube according to the first embodiment. The rotating anode X-ray tube includes a rotating body 1, a fixed shaft 2 inserted into the rotating body 1, a first fixed cylinder 3 and a second fixed cylinder 4, a cathode 10, and a vacuum envelope 11. Prepare.

  The rotating body 1 is rotatably supported by a bearing around the fixed shaft 2. As this bearing, for example, a dynamic pressure type sliding bearing using a liquid metal LM can be adopted. The cathode 10 emits electrons. The vacuum envelope 11 accommodates the rotating body 1, the fixed shaft 2, the first fixed cylinder 3, the second fixed cylinder 4, the cathode 10, and the like.

  A rotary anode X-ray tube is used in a rotary anode X-ray tube device together with a stator coil 12 (rotation drive unit), a casing, insulating oil (coolant), and the like. The stator coil 12 is disposed at a position facing the rotating body 1 with the vacuum envelope 11 in between. The stator coil 12 generates a magnetic field when supplied with a predetermined current. The rotating body 1 rotates around the fixed shaft 2 by the action of this magnetic field. The housing accommodates the rotary anode X-ray tube, the stator coil 12 and the like. Insulating oil is filled in the space between the rotary anode X-ray tube and the housing.

  The rotating body 1 includes an anode target 5, a first rotating cylinder 6, a second rotating cylinder 7, a third rotating cylinder 8, and a fourth rotating cylinder 9.

  For example, the fixed shaft 2, the first fixed cylinder 3, the second fixed cylinder 4, the anode target 5, the first rotating cylinder 6, the second rotating cylinder 7, the third rotating cylinder 8, and the fourth rotating cylinder 9 are Also, the cross-section in all directions along the axis of rotation A has a point-symmetric shape with respect to the axis A.

  The cathode 10 is fixedly arranged, for example, on the right side of the anode target 5 in FIG. The surface of the anode target 5 facing the cathode 10 is inclined. Electrons emitted from the cathode 10 collide with the inclined surface. The anode target 5 generates X-rays in response to collision of electrons emitted from the cathode 10. The cross-sectional shape of the anode target 5 along the axis A is, for example, an annular shape. The anode target 5 is formed of, for example, molybdenum or tungsten, or an alloy using these.

  The first rotating cylinder 6 has a cylindrical shape with both ends opened. The first rotating cylinder 6 is made of, for example, molybdenum, tungsten, or an alloy using these. In particular, in the present embodiment, the first rotating cylinder 6 is formed integrally with the anode target 5.

  The 2nd rotation cylinder 7 and the 4th rotation cylinder 9 comprise the cylinder shape which the both ends opened. The second rotating cylinder 7 and the fourth rotating cylinder 9 are formed of a metal material such as an iron alloy. The first rotating cylinder 6 and the fourth rotating cylinder 9 may be integrally formed of the same material.

  The third rotating cylinder 8 has a cylindrical shape with both ends opened. The third rotating cylinder 8 is formed of a metal material such as copper or a copper alloy, for example. The third rotating cylinder 8 receives the magnetic field generated by the stator coil 12 and generates torque that rotates the rotating body 1 around the fixed shaft 2.

  The first rotating cylinder 6 and the third rotating cylinder 8, the first rotating cylinder 6 and the fourth rotating cylinder 9, the second rotating cylinder 7 and the third rotating cylinder 8, and the second rotating cylinder 7 and the fourth rotating cylinder 9 are Are fixed to each other. As the fixing method, for example, the inner cylinder of the two cylinders is cooled and contracted, the inner cylinder is inserted into the outer cylinder, and the outer cylinder of the two cylinders is heated. Then, it is possible to use an interference fit such as a shrink fit that expands and inserts a cylinder located inside the cylinder into the cylinder, or a press fit that press-fits the cylinder located inside of the two cylinders into the cylinder located outside. Further, welding, brazing, caulking, screw connection, pinning, or the like may be used as the fixing method. In the case of using screw connection, the inner wall of the outer cylinder of the two cylinders may be a female screw, the outer wall of the inner cylinder may be a male screw, and the female screw and the male screw may be screwed together.

  The first rotating cylinder 6 has an annular protruding portion 6a at the right end in FIG. Due to the protruding portion 6a, the inside of the first rotating cylinder 6 is narrowed at the right end. On the other hand, the inside of the first rotating cylinder 6 is expanded at the left end in FIG. Due to the expanded portion and the side wall of the fourth rotating cylinder 9, an annular recess portion 6 b is formed inside the rotating body 1.

  The fixed shaft 2 has, for example, a hollow cylindrical shape with both ends opened. The fixed shaft 2 has an annular projecting portion 2a projecting outward at the left end in FIG. The protruding portion 2a has a shape that fits in the recessed portion 6b with a gap. The fixed shaft 2 is formed of, for example, molybdenum or tungsten, or an alloy using these. The left and right edges of the fixed shaft 2 are planes perpendicular to the direction parallel to the axis A.

  The first fixed cylinder 3 has, for example, a cylindrical shape with both ends opened. The first fixed cylinder 3 has an outer shape smaller than the fixed shaft 2 and is inserted into the fixed shaft 2 from the left in FIG. The first fixed cylinder 3 is formed of a metal material such as an iron alloy or stainless steel.

  The second fixed cylinder 4 has, for example, a cylindrical shape with both ends opened. The second fixed cylinder 4 has an outer shape smaller than that of the fixed shaft 2, and is inserted into the fixed shaft 2 from the right side in FIG. The second fixed cylinder 4 is formed of a metal material such as an iron alloy or stainless steel.

  The first fixed cylinder 3 has an annular guide 3a along the outer wall. The left and right side walls in FIG. 1 of the guide 3a are planes perpendicular to the direction parallel to the axis A.

  The second fixed cylinder 4 has an annular guide 4a along the outer wall. The left and right side walls in FIG. 1 of the guide 4a are planes perpendicular to the direction parallel to the axis A.

  The right side wall of the guide 3a in FIG. 1 is joined to the left edge of the fixed shaft 2 in FIG. That is, the fixed shaft 2 and the first fixed cylinder 3 are joined at the first surface F1 that intersects the direction parallel to the axis A. More specifically, the first surface F1 in the present embodiment is a surface perpendicular to the direction parallel to the axis A.

  The outer wall of the first fixed cylinder 3 on the right side of the guide 3 a in FIG. 1 is joined to the inner wall of the fixed shaft 2. That is, the fixed shaft 2 and the first fixed cylinder 3 are joined at a plurality of surfaces that intersect each other.

  The left side wall of the guide 4a in FIG. 1 is joined to the right edge of the fixed shaft 2 in FIG. That is, the fixed shaft 2 and the second fixed cylinder 4 are joined at the second surface F2 that intersects the direction parallel to the axis A. More specifically, the second surface F2 in the present embodiment is a surface perpendicular to the axis A.

  The outer wall of the second fixed cylinder 4 on the left side of the guide 4 a in FIG. 1 is joined to the inner wall of the fixed shaft 2. That is, the fixed shaft 2 and the second fixed cylinder 4 are joined at a plurality of surfaces that intersect each other.

A method for joining the fixed shaft 2 to the first fixed cylinder 3 and the second fixed cylinder 4 will be described.
FIG. 2 is a view for explaining a method of joining the fixed shaft 2 with the first fixed cylinder 3 and the second fixed cylinder 4. The fixed shaft 2, the first fixed cylinder 3, and the second fixed shaft 2 shown in FIG. The sectional view of the fixed cylinder 4 is shown enlarged.

  The fixed shaft 2 has a female screw 21 provided as a starting point near the end portion of the inner wall on the protruding portion 2a side, and a female screw 22 provided as a starting point near the end portion on the side opposite to the protruding portion 2a of the inner wall.

  The first fixed cylinder 3 has a male screw 31 provided starting from the guide 3a. The pitch and effective diameter of the male screw 31 are substantially the same as those of the female screw 21. The second fixed cylinder 4 has a male screw 41 provided starting from the guide 4a. The pitch and effective diameter of the male screw 41 are substantially the same as those of the female screw 22.

  The first fixed cylinder 3 is attached to the fixed shaft 2 by fastening the male screw 31 to the female screw 21 of the fixed shaft 2. That is, in this embodiment, the outer wall of the first fixed cylinder 3 and the inner wall of the fixed shaft 2 are joined by screw connection. In the present embodiment, the first surface F1 is joined by brazing.

  The second fixed cylinder 4 is attached to the fixed shaft 2 by tightening the male screw 41 to the female screw 22 of the fixed shaft 2. That is, in this embodiment, the outer wall of the second fixed cylinder 4 and the inner wall of the fixed shaft 2 are joined by screw connection. In the present embodiment, the above-described second surface F2 is joined by brazing.

  In FIG. 2, the part joined by brazing is enclosed by the rectangular broken line.

  Inside the fixed shaft 2, the tip of the first fixed cylinder 3 and the tip of the second fixed cylinder 4 are separated from each other at a position where the anode target 5 is located around. Thereby, the internal diameter of the shaft member comprised by the fixed shaft 2, the 1st fixed cylinder 3, and the 2nd fixed cylinder 4 expands. The thickness of the shaft member is reduced around the portion where the inner diameter is enlarged. Therefore, heat generated in the rotating body 1 is easily transmitted to the inside of the shaft member. For example, the heat can be effectively exhausted by passing the coolant through the shaft member. In addition, the temperature of the bearing surface can be lowered, and thereby the reaction between the liquid metal LM and the bearing surface is suppressed, so that the life of the bearing can be extended.

  Thus, even if an attempt is made to manufacture a shaft member whose inner portion has an inner diameter larger than the inner diameter of the end portion by cutting (nagulation), it is technically difficult to sufficiently increase the inner diameter of the intermediate portion. Furthermore, when the material of the shaft member is a hard metal such as molybdenum, cutting becomes more difficult. On the other hand, in the configuration in which the first fixed cylinder 3 and the second fixed cylinder 4 are respectively inserted from both ends of the fixed shaft 2 as in the present embodiment, the shaft member can have a sufficient inner diameter.

  When the fixed shaft 2, the first fixed cylinder 3 and the second fixed cylinder 4 are formed of materials having different thermal expansion coefficients, the fixed shaft 2, the first fixed cylinder 3, and the fixed shaft at the time of thermal expansion or contraction. A shearing force along a direction parallel to the axis A acts between the second fixed cylinder 4 and the second fixed cylinder 4. In the method in which the first fixed cylinder 3 and the second fixed cylinder 4 are attached to the fixed shaft 2 only by joining the inner wall of the fixed shaft 2 and the outer walls of the first fixed cylinder 3 and the second fixed cylinder 4, this shearing force results. Peeling may occur.

  On the other hand, in this embodiment, the joint surface between the fixed shaft 2 and the first fixed cylinder 3 and the second fixed cylinder 4 is the inner wall of the fixed shaft 2 and the outer wall of the first fixed cylinder 3 and the second fixed cylinder 4. As well as a first surface F1 and a second surface F2 that intersect the direction of the axis A. Therefore, it becomes difficult to peel off the joint surface. As a result, leakage of the liquid metal LM into the vacuum envelope 11 and a decrease in the degree of vacuum in the vacuum envelope 11 can be prevented, and the performance of the rotary anode X-ray tube can be kept good.

(Second Embodiment)
A second embodiment will be described.
The second embodiment differs from the first embodiment in the method of joining the fixed shaft 2 with the first fixed cylinder 3 and the second fixed cylinder 4. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 3 is a diagram for explaining a bonding method according to the second embodiment.
In the present embodiment, the fixed shaft 2 does not have the female screws 21 and 22, the first fixed cylinder 3 does not have the male screw 31, and the second fixed cylinder 4 does not have the male screw 41.

  The inner wall of the fixed shaft 2 and the outer wall of the first fixed cylinder 3 are joined by brazing. The first surface F1 described above is joined by brazing.

  The inner wall of the fixed shaft 2 and the outer wall of the second fixed cylinder 4 are joined by brazing. The second surface F2 described above is joined by brazing.

  In FIG. 3, the part joined by brazing is enclosed by the rectangular broken line.

  Even when the fixed shaft 2 and the first fixed cylinder 3 and the second fixed cylinder 4 are joined as in the present embodiment, separation at the joint surface can be prevented as in the first embodiment. As a result, leakage of the liquid metal LM into the vacuum envelope 11 and a decrease in the degree of vacuum in the vacuum envelope 11 can be prevented, and the performance of the rotary anode X-ray tube can be kept good.

(Third embodiment)
A third embodiment will be described.
The third embodiment differs from the first and second embodiments in the method of joining the fixed shaft 2 with the first fixed cylinder 3 and the second fixed cylinder 4. The same elements as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

FIG. 4 is a diagram for explaining a bonding method according to the third embodiment.
The fixed shaft 2 has female screws 21 and 22 as in the first embodiment. The first fixed cylinder 3 has a male screw 31 as in the first embodiment. The second fixed cylinder 4 has a male screw 41 as in the first embodiment.

  The first fixed cylinder 3 is attached to the fixed shaft 2 by fastening the male screw 31 to the female screw 21 of the fixed shaft 2. Furthermore, the connection part of the internal thread 21 and the external thread 31 is brazed. That is, in this embodiment, the outer wall of the first fixed cylinder 3 and the inner wall of the fixed shaft 2 are joined by screw connection and brazing. The first surface F1 described above is joined by brazing.

  The second fixed cylinder 4 is attached to the fixed shaft 2 by tightening the male screw 41 to the female screw 22 of the fixed shaft 2. Furthermore, the connection part of the internal thread 22 and the external thread 41 is brazed. That is, in this embodiment, the outer wall of the second fixed cylinder 4 and the inner wall of the fixed shaft 2 are joined by screw connection and brazing. The second surface F2 described above is joined by brazing.

  In FIG. 4, the part joined by brazing is enclosed by the rectangular broken line.

  Even when the fixed shaft 2 and the first fixed cylinder 3 and the second fixed cylinder 4 are joined as in the present embodiment, separation at the joint surface can be prevented as in the first embodiment. As a result, leakage of the liquid metal LM into the vacuum envelope 11 and a decrease in the degree of vacuum in the vacuum envelope 11 can be prevented, and the performance of the rotary anode X-ray tube can be kept good.

  Particularly when the inner wall of the fixed shaft 2 and the outer walls of the first fixed cylinder 3 and the second fixed cylinder 4 are joined by both screw connection and brazing as in the present embodiment, the fixed shaft 2 and the first Since the fixed cylinder 3 and the second fixed cylinder 4 are strongly joined, the vacuum in the vacuum envelope 11 is easily maintained.

(Modification)
Besides the methods disclosed in the first to third embodiments, various methods can be adopted as a method for fixing the fixed shaft 2 to the first fixed cylinder 3 and the second fixed cylinder 4. For example, the fixed shaft 2 and the first fixed cylinder 3 and the second fixed cylinder 4 may be joined by cold fitting, shrink fitting, interference fitting such as press fitting, or welding.

  The first surface F1 and the second surface F2 are not limited to surfaces perpendicular to the direction parallel to the axis A. For example, the first surface F1 and the second surface F2 may be surfaces inclined with respect to a direction parallel to the axis A.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Rotating body, 2 ... Fixed axis | shaft, 2a ... Projection part, 3 ... 1st fixed cylinder, 3a ... Guide, 4 ... 2nd fixed cylinder, 4a ... Guide, 5 ... Anode target, 6 ... 1st rotary cylinder, 6a DESCRIPTION OF SYMBOLS ... Projection part, 6b ... hollow part, 7 ... 2nd rotation cylinder, 8 ... 3rd rotation cylinder, 9 ... 4th rotation cylinder, 1,22 ... Female thread, 1,41 ... Male thread, A ... Shaft of rotation.

Claims (6)

A hollow fixed shaft that rotatably supports a rotating body having an anode target;
A first fixed cylinder and a second fixed cylinder inserted into the fixed shaft from the openings on both sides and joined to the fixed shaft;
With
The joint surface between the fixed shaft and the first fixed cylinder and the second fixed cylinder includes a surface that intersects a direction parallel to the axis of the fixed shaft.
Rotating anode X-ray tube. The fixed shaft, the first fixed cylinder, and the second fixed cylinder are a screw portion provided on an inner wall of the fixed shaft, and a screw portion provided on an outer wall of the first fixed cylinder and the second fixed cylinder. Are joined by brazing each of the surfaces intersecting with a direction parallel to the axis of the fixed shaft,
The rotary anode X-ray tube according to claim 1. The fixed shaft, the first fixed cylinder, and the second fixed cylinder are a surface that intersects a direction parallel to the axis of the fixed shaft, an inner wall of the fixed shaft, and the first fixed cylinder and the second fixed cylinder. Joined by brazing the outer wall,
The rotary anode X-ray tube according to claim 1. The fixed shaft, the first fixed cylinder, and the second fixed cylinder are a screw portion provided on an inner wall of the fixed shaft, and a screw portion provided on an outer wall of the first fixed cylinder and the second fixed cylinder. And are joined by brazing the inner wall of the fixed shaft, the outer walls of the first fixed cylinder and the second fixed cylinder, and the surfaces intersecting the direction parallel to the axis of the fixed shaft, respectively.
The rotary anode X-ray tube according to claim 1. The surface intersecting with the direction parallel to the axis of the fixed axis is a surface perpendicular to the direction parallel to the axis of the fixed axis.
The rotary anode type X-ray tube according to any one of claims 1 to 4. Between the tips of the first fixed cylinder and the second fixed cylinder inserted in the fixed shaft, a gap is provided at a position where the anode target is located in the periphery, and the fixed shaft, the first The inner diameter of the member consisting of the first fixed cylinder and the second fixed cylinder is enlarged.
The rotary anode type X-ray tube according to any one of claims 1 to 4.

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