JP2012104391A - Rotating anode x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating anode X-ray tube capable of suppressing damage due to heat deformation between components.SOLUTION: In a rotating anode X-ray tube, a rotor 10 of a dynamic-pressure sliding bearing comprises: a target support which supports an anode target 4; a bearing cylinder 12 which is arranged inside the target support 11; a first cylinder 13 which is made of a material having a heat expansion coefficient substantially equal to that of the target support, and has one end bonded to the target support and the other end bonded to the bearing cylinder, and which constitutes a strength structure to support the anode target subject to electron impact; and a second cylinder 14 which is made of a material having a heat expansion coefficient greater than that of the first cylinder, and which forms a passage to transfer heat from the one end of the first cylinder bonded to the target support to the bearing cylinder.

Description

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

  The rotary anode type X-ray tube is provided with a cathode that emits electrons in a container in a high vacuum and an anode target that rotates in opposition thereto, and the electric field emitted between the cathode and the anode target is provided between the cathode and the anode target. And irradiating the rotating anode target with X-rays by bremsstrahlung radiation.

  The anode target may reach an average temperature of 1000 ° C. or higher due to electron impact heating. For this reason, a metal material that has sufficient mechanical strength and low thermal conductivity at high temperatures is used to protect the rotating mechanism that supports and smoothly rotates the heat conducted from the anode target. In addition, a heat insulating structure that makes the coupling path between the anode target and the rotating mechanism complicated and returns a long heat propagation path is adopted, and the anode target is cooled by radiation or a part of the heat of the anode target is a structure. There is a system that uses conduction cooling that cools by cooling to a cooling medium such as insulating oil that has flowed into the stationary side structure that supports the bearing through the bearing portion of the rotation mechanism while being limited by the thermal resistance of the rotating mechanism.

  In the case of conduction cooling, there is a method in which the entire bearing is manufactured using a molybdenum-based material with high heat resistance. However, the molybdenum-based material is high in both material cost and processing cost, and the bearing is galling. There are easy problems.

  On the other hand, between members having relatively different thermal conductivities or coefficients of thermal expansion, a large stress is generated in a high temperature environment, and in some cases, the members may be damaged.

Japanese Patent Application Laid-Open No. 07-130311 JP 2003-217490 A

  An object of the present embodiment is to provide a rotary anode type X-ray tube capable of suppressing breakage due to thermal deformation between members.

According to this embodiment,
A cathode that emits electrons; an anode target that emits X-rays when electrons emitted from the cathode are incident; a rotator coupled to the anode target; and a columnar shape that rotatably supports the rotator. A hydrodynamic slide bearing composed of a fixed body, and a liquid refrigerant held between the rotating body and the fixed body, and a vacuum containing the anode target, the cathode, and the hydrodynamic slide bearing A rotary anode type X-ray tube comprising: an envelope; and the rotating body includes a target support for supporting the anode target, a bearing cylinder disposed inside the target support, and the target support. It is made of a material having substantially the same thermal expansion coefficient, and has one end joined to the target support and the other end joined to the bearing cylinder, and receives an electron impact. A first cylinder forming a strength structure for supporting the anode target, and the one end portion of the first cylinder formed of a material having a larger thermal expansion coefficient than the first cylinder and joined to the target support. And a second cylinder for forming a path for conducting heat from the bearing cylinder to the bearing cylinder.

According to this embodiment,
A cathode that emits electrons; an anode target that emits X-rays when electrons emitted from the cathode are incident; a rotator coupled to the anode target; and a columnar shape that rotatably supports the rotator. A hydrodynamic slide bearing composed of a fixed body, and a liquid refrigerant held between the rotating body and the fixed body, and a vacuum containing the anode target, the cathode, and the hydrodynamic slide bearing A rotary anode type X-ray tube comprising: an envelope; and the rotating body includes a target support for supporting the anode target, a bearing cylinder disposed inside the target support, and the target support. A first cylinder having one end joined and the other end joined to the bearing cylinder; and a second series formed of a material having a larger thermal expansion coefficient than the first cylinder. A first end that is spaced apart from the bearing cylinder and protrudes toward the one end of the first cylinder and is joined to the one end, and the first cylinder A second end portion that is spaced apart from and protrudes toward the bearing cylinder and is joined to the bearing cylinder; and a first end portion and the second end that are spaced apart from the bearing cylinder and the first cylinder. And a connecting portion having a radial thickness thinner than that of the first end and the second end, and the length of the connecting portion along the tube axis direction of the first cylinder is There is provided a rotary anode X-ray tube characterized by being shorter than the length along the tube axis direction between the one end and the other end.

According to this embodiment,
A cathode that emits electrons; an anode target that emits X-rays when electrons emitted from the cathode are incident; a rotator coupled to the anode target; and a columnar shape that rotatably supports the rotator. A hydrodynamic slide bearing composed of a fixed body, and a liquid refrigerant held between the rotating body and the fixed body, and a vacuum containing the anode target, the cathode, and the hydrodynamic slide bearing A rotary anode type X-ray tube comprising: an envelope; and the rotating body includes a target support for supporting the anode target, a bearing cylinder disposed inside the target support, and the target support. A first cylinder having one end joined and the other end joined to the bearing cylinder; and a second series formed of a material having a larger thermal expansion coefficient than the first cylinder. A first end portion that is spaced apart from the bearing cylinder and protrudes toward the one end portion of the first cylinder and slidably contacts the one end portion. A second end spaced apart from the first cylinder and projecting toward the bearing cylinder and joined to the bearing cylinder; and spaced apart from the bearing cylinder and the first cylinder and the first end A rotary anode X-ray tube comprising: a first end portion and a connecting portion that is thinner than the first end portion and the second end portion. The

FIG. 1 is a diagram schematically showing a configuration example of a main part of a rotary anode X-ray tube in the present embodiment. FIG. 2 is a cross-sectional view showing a structural example of a rotating body applicable to the rotating anode X-ray tube shown in FIG. FIG. 3 is a perspective view showing a structural example of a second cylinder constituting the rotating body shown in FIG. FIG. 4 is a view for explaining the state of thermal expansion along the tube axis direction of the first cylinder and the second cylinder in the configuration of the present embodiment. FIG. 5 is a diagram for explaining the state of thermal expansion along the radial direction of the first cylinder and the second cylinder in the configuration of the present embodiment. FIG. 6 is a cross-sectional view showing another structural example of a rotating body applicable to the rotating anode X-ray tube shown in FIG.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. In each figure, the same reference numerals are given to components that exhibit the same or similar functions, and duplicate descriptions are omitted.

  FIG. 1 is a diagram schematically showing a configuration example of a main part of a rotary anode X-ray tube 1 in the present embodiment.

  That is, the rotary anode X-ray tube 1 includes a vacuum envelope 2, a cathode 3, an anode target 4, a dynamic pressure type slide bearing 5, and the like. The vacuum envelope 2 is formed of, for example, glass, and the internal space 2A is maintained at a high vacuum. The vacuum envelope 2 has an X-ray output window 2W provided in a part thereof. In such a vacuum envelope 2, a cathode 3, an anode target 4, a dynamic pressure type slide bearing 5 and the like are accommodated.

  The cathode 3 is an electron source that emits electrons. The cathode 3 is disposed at a position away from the tube axis (or rotation axis) O of the rotary anode X-ray tube 1 and faces the anode target 4. Such a cathode 3 is supported inside the vacuum envelope 2 by a support mechanism (not shown). In the following description, the tube axis direction corresponds to a direction parallel to the tube axis O.

  The anode target 4 emits X-rays when electrons emitted from the cathode 3 enter. The anode target 4 is formed in a substantially disc shape, and a part of the anode target 4 faces the cathode 3. The anode target 4 formed in a disk shape in this way is connected to a hydrodynamic slide bearing 5 which is a rotation support mechanism at a substantially center thereof and is rotatably supported.

  The hydrodynamic slide bearing 5 includes a rotating body 10, a fixed body 6, and a liquid refrigerant 7 held between the rotating body 10 and the fixed body 6.

  The rotating body 10 is formed in a cylindrical shape extending along the tube axis O. The structure of the rotating body 10 will be described later in detail, but one end side along the tube axis O is closed, and the other end side along the tube axis O is open. The anode target 4 is connected to one end side of the rotating body 10.

  The fixed body 6 is fitted to the rotating body 10 having the above-described configuration, and supports the rotating body 10 so as to be rotatable. The fixed body 6 is formed in a cylindrical shape extending along the tube axis O. In such a fixed body 6, for example, a flow path 6 </ b> A for circulating insulating oil is formed as a cooling medium.

  In the illustrated example, the flow path 6A is a circulation path that extends substantially along the tube axis O at the center of the fixed body 6 and is turned back at the tip. As shown by the arrows in the figure, the cooling medium flows upward from the center of the fixed body 6, that is, toward the anode target 4 in the flow path 6 </ b> A, turns back at the tip, and flows out of the tube on the atmospheric pressure side. .

  The liquid refrigerant 7 is made of a liquid metal having a relatively low vapor pressure in a vacuum, such as an indium (In) -gallium (Ga) alloy. The liquid refrigerant 7 is filled in a gap between the rotating body 10 and the fixed body 6 and is held by the surface tension. The liquid refrigerant 7 is not limited to the above example.

  FIG. 2 is a cross-sectional view showing a structural example of a rotating body 10 applicable to the rotary anode X-ray tube 1 shown in FIG. Here, only the configuration necessary for the description is schematically illustrated, and the right half of the rotary anode X-ray tube 1 illustrated in FIG. 1 is illustrated in an enlarged manner.

  The fixed body 6 fitted to the rotating body 10 is formed in a columnar shape extending along the tube axis O. A liquid refrigerant 7 is sealed between the fixed body 6 and the rotating body 10. A herringbone pattern 6H for scraping the liquid refrigerant 7 is provided on the side surface 6S of the fixed body 6 as described above.

  The rotating body 10 includes a target support 11, a bearing cylinder 12, a first cylinder 13, and a second cylinder 14.

  The target support 11 supports the anode target 4 having an umbrella shape, and is formed in a cylindrical shape extending along the tube axis O. The target support 11 is joined to the anode target 4 at one end side thereof. Further, the target support 11 has a lower end portion 11 </ b> A on the side opposite to the bonding portion with the anode target 4, that is, on the side away from the anode target 4. The anode target 4 and the target support 11 are formed using a molybdenum (Mo) alloy that is a material having excellent heat resistance and high strength at high temperatures.

  The bearing cylinder 12 is disposed inside the target support 11. This bearing cylinder is formed in a cylindrical shape extending along the tube axis O. The bearing cylinder 12 has a first joint 12A, which will be described later, and a second joint 12B located on the anode target 4 side of the first joint 12A along the tube axis direction. Such a bearing cylinder 12 is formed using an iron (Fe) -based material. A fixed body 6 is fitted inside the bearing cylinder 12 via a liquid refrigerant 7.

  The first cylinder 13 is formed of a material having a thermal expansion coefficient substantially equal to that of the target support 11. In particular, the first cylinder 13 is a Kovar that has a thermal expansion coefficient substantially the same as that of the target support 11 but is different from a molybdenum-based alloy and has excellent heat resistance and high temperature strength. An alloy (iron-nickel-cobalt alloy) is used. Kovar alloy has substantially the same characteristics as molybdenum alloy, but is cheaper than molybdenum alloy, so that the amount of molybdenum alloy used can be reduced and the cost can be reduced. Such a first cylinder 13 forms a strength structure for supporting the anode target 4 that receives an electron impact.

  The first cylinder 13 is formed in a cylindrical shape extending along the tube axis O, and has one end 13A joined to the target support 11, the other end 13B joined to the bearing cylinder 12, and one end. It has an intermediate portion 13C between 13A and the other end 13B. The one end portion 13A is located on the anode target 4 side along the tube axis direction, and the other end portion 13B is located on the side farther from the anode target 4 along the tube axis direction than the one end portion 13A.

  More specifically, the first cylinder 13 is disposed inside the target support 11 and outside the bearing cylinder 12. The outer diameter of the first cylinder 13 is substantially the same as the inner diameter of the target support 11. In such a first cylinder 13, the one end 13 </ b> A is joined to the lower end 11 </ b> A of the target support 11. At this time, the inner peripheral surface of the lower end portion 11A of the target support 11 and the outer peripheral surface of the first end portion 13A of the first cylinder 13 are joined. In the first cylinder 13, the other end 13 </ b> B is joined to the first joint 12 </ b> A of the bearing cylinder 12.

  The joining of the target support 11 and the first cylinder 13 and the joining of the bearing cylinder 12 and the first cylinder 13 are performed by, for example, techniques such as welding, brazing, and screwing.

  In such a first cylinder 13, the intermediate portion 13 </ b> C is not joined to any of the target support 11, the bearing cylinder 12, and the like, and becomes a non-fixed portion having a relatively high degree of freedom. It tends to cause expansion or contraction. Here, the length along the tube axis direction between the one end portion 13A and the other end portion 13B of the first cylinder 13, that is, the length along the tube axis direction of the intermediate portion 13C is defined as L1.

  The second cylinder 14 is made of a material having a larger thermal expansion coefficient (or higher thermal conductivity) than the first cylinder 13. In particular, here, the second cylinder 14 is made of copper (Cu), an alloy containing copper as a main component, or alumina-dispersed copper. Such a second cylinder 14 forms a path for conducting heat from the one end 13 </ b> A of the first cylinder 13 joined to the target support 11 to the bearing cylinder 12.

  The second cylinder 14 is formed in a cylindrical shape extending along the tube axis O, and the first end 14A joined to the one end 13A of the first cylinder 13 and the second end joined to the bearing cylinder 12. It has the end part 14B and the connecting part 14C that connects the first end part 14A and the second end part 14B. In such a second cylinder 14, the first end portion 14A is positioned on the anode target 4 side along the tube axis direction, and the second end portion 14B is an anode target along the tube axis direction from the first end portion 14A. Located on the side away from 4.

  More specifically, the second cylinder 14 is disposed inside the first cylinder 13 and outside the bearing cylinder 12. Further, the length of the second cylinder 14 along the tube axis direction is shorter than the length of the first cylinder 13 along the tube axis direction.

  In the second cylinder 14, the first end portion 14 </ b> A is separated from the bearing cylinder 12. The first end portion 14 </ b> A protrudes toward the one end portion 13 </ b> A of the first cylinder 13. The second end portion 14 </ b> B is separated from the first cylinder 13. The second end portion 14B protrudes toward the bearing cylinder 12. The radial thicknesses of the first end portion 14A and the second end portion 14B are relatively thick. The connecting portion 14 </ b> C is separated from the bearing cylinder 12 and the first cylinder 13. Further, the radial thickness of the connecting portion 14C is thinner than the radial thickness of each of the first end portion 14A and the second end portion 14B.

  In such a second cylinder 14, the first end portion 14 </ b> A includes an outer peripheral surface protruding outward in the radial direction. The outer diameter of the first end portion 14A (that is, the diameter of the outer peripheral surface having a circular cross section) is substantially the same as the inner diameter of the first cylinder 13. The outer peripheral surface of the first end portion 14 </ b> A is joined to the inner peripheral surface of the one end portion 13 </ b> A of the first cylinder 13. The position along the tube axis direction where the one end portion 13A and the first end portion 14A are joined is substantially the same as the position along the tube axis direction where the lower end portion 11A and the one end portion 13A are joined. That is, the one end portion 13A is sandwiched between the lower end portion 11A and the first end portion 14A.

  In the second cylinder 14, the second end portion 14 </ b> B includes an inner peripheral surface that protrudes inward in the radial direction. The inner diameter of the second end portion 14B (that is, the diameter of the inner peripheral surface having a circular cross section) is substantially the same as the outer diameter of the second joint portion 12B of the bearing cylinder 12. The inner peripheral surface of the second end portion 14B is joined to the outer peripheral surface of the first joint portion 12B of the bearing cylinder 12. The position along the tube axis direction where the second joint portion 12B and the second end portion 14B are joined is more anode than the position along the tube axis direction where the first joint portion 12A and the other end portion 13B are joined. The target 4 side.

  The joining between the first cylinder 13 and the second cylinder 14 and the joining between the bearing cylinder 12 and the second cylinder 14 are performed by a technique such as welding, brazing, and screwing.

  In such a second cylinder 14, the connecting portion 14 </ b> C is not joined to either the bearing cylinder 12, the first cylinder 13, or the like, and becomes a non-fixed portion. In addition, since the connecting portion 14C has a smaller thickness than the first end portion 14A and the second end portion 14B, the degree of freedom is high, and relatively large thermal deformation (ie, expansion or contraction) is likely to occur.

  Here, the length along the tube axis direction between the first end portion 14A and the second end portion 14B of the second cylinder 14, that is, the length along the tube axis direction of the connecting portion 14C is defined as L2. . At this time, the length L2 along the tube axis direction of the connecting portion 14C is shorter than the length L1 along the tube axis direction of the intermediate portion 13C of the first cylinder 13.

  FIG. 3 is a perspective view showing an example of the structure of the second cylinder 14 constituting the rotating body 10 shown in FIG.

  In the second cylinder 14, the first end portion 14 </ b> A, the second end portion 14 </ b> B, and the connecting portion 14 </ b> C are each formed in a cylindrical shape that extends along the tube axis O. The first end portion 14A includes an outer peripheral surface 14O. The outer peripheral surface 14O is a cylindrical surface extending along the tube axis O, and is joined to the target support 11 over the entire surface. The second end portion 14B includes an inner peripheral surface 14I. The inner peripheral surface 14I is a cylindrical surface extending along the tube axis O, and is joined to the bearing cylinder 12 over the entire surface.

  In other words, the second cylinder 14 has a first notch C1 that forms a gap with the bearing cylinder 12 inside the outer peripheral surface 14O that is joined to the first cylinder 13, and an inner peripheral surface 14I that is joined to the bearing cylinder. And a second notch C <b> 1 that forms a gap with the first cylinder 13. The first notch C1 and the second notch C2 are both formed in an annular shape. A part of the second notch C2 is positioned outside a part of the first notch C1.

  That is, the first notch C1 extends from the first end portion 14A to the connecting portion 14C. The second notch C2 extends from the second end portion 14B to the connecting portion 14C. That is, the first cutout C1 is formed inside the connecting portion 14C, and the second cutout C2 is formed outside the connecting portion 14C.

  According to such a configuration, when the heat generated in the anode target 4 is conducted to the hydrodynamic slide bearing 5, it is radiated and cooled as follows. That is, the heat generated in the anode target 4 is transmitted to the rotating body 10 constituting the dynamic pressure type slide bearing 5. The heat conducted to the rotating body 10 is transmitted to the bearing cylinder 12 through the target support 11, the first cylinder 13 and the second cylinder 14. The heat transmitted to the bearing cylinder 12 is transmitted to the side surface 6S of the fixed body 6 through the liquid refrigerant 7. The heat transmitted to the side surface 6S of the fixed body 6 is transmitted to the cooling medium circulating inside the fixed body 6, and is carried away outside the pipe by the cooling medium. Thereby, at least 1% or more of the heat from the anode target 4 is conducted to the cooling medium and cooled.

  When transferring the heat, the first cylinder 13 is formed of a material having a thermal expansion coefficient substantially equal to that of the target support 11. Therefore, when the first cylinder 13 is thermally expanded together with the target support 11, a large stress is applied to the joint surface between them. Does not occur. Since the first cylinder 13 forms a strength structure for supporting the anode target 4, the material is required to have a high mechanical strength, but a high thermal conductivity is not required. On the other hand, since the second cylinder 14 forms a heat transfer path from the first cylinder 13 to the bearing cylinder 12, the material is required to have a high thermal conductivity. A material having such a large thermal conductivity has a large expansion coefficient.

  That is, the thermal expansion coefficient of the second cylinder 14 is larger than the thermal expansion coefficient of the first cylinder 13. For this reason, the thermal expansion amount per unit length of the second cylinder 14 is larger than the thermal expansion amount per unit length of the first cylinder 13 in each of the tube axis direction and the radial direction. A large thermal stress is generated between the first cylinder 13 and the second cylinder 14 having different coefficients of thermal expansion due to the difference in the amount of thermal expansion per unit length. In addition, a large thermal stress is generated in the members joined to the first cylinder 13 and the second cylinder 14 with thermal expansion or deformation. For this reason, a structure for coping with such thermal stress is required.

  In the present embodiment, in order to absorb the difference in thermal expansion amount per unit length along the tube axis direction of the first cylinder 13 and the second cylinder 14, the first cylinder 13 having a small coefficient of thermal expansion is not fixed. The length L1 along the tube axis direction of the intermediate portion 13C serving as the portion is set to be longer than the length L2 along the tube axis direction of the connecting portion 14C serving as the non-fixed portion in the second cylinder 14 having a large coefficient of thermal expansion. Has been.

  FIG. 4 is a diagram for explaining the state of thermal expansion along the tube axis direction of the first cylinder 13 and the second cylinder 14 in the configuration of the present embodiment.

  During the heat transfer described above, in the first cylinder 13, the one end 13A close to the anode target becomes high temperature, the other end 13B away from the anode target becomes low temperature, and a relatively large temperature gradient is formed. A large temperature difference is formed at the other end 13B. In the second cylinder 14, a temperature gradient as great as that of the first cylinder 13 is not formed, and the temperature difference between the first end portion 14A and the second end portion 14B is relatively small.

  In view of the above-described temperature gradient during operation in the first cylinder 13 and the second cylinder 14, the length L1 of the intermediate portion 13C and the length L2 of the connecting portion 14C are units in the temperature distribution during operation. It is set so as to cancel out the difference in thermal expansion amount per length. Such an appropriate ratio or value of the lengths L1 and L2 is calculated by, for example, the finite element method.

  Thus, when thermal expansion occurs in both the first cylinder 13 and the second cylinder 14, the total expansion amount α in the first cylinder 13 and the total expansion amount β in the second cylinder 14 are balanced. That is, as shown on the left side in the drawing, when not operating (before thermal expansion), the length of the intermediate portion 13C of the first cylinder 13 is L1, and the length of the connecting portion 14C of the second cylinder 14 is L2. It is. And, as shown on the right side in the figure, during operation (during expansion), the length of the intermediate portion 13C becomes a length L1 ′ obtained by adding the total expansion amount α to the initial length L1, The length of the connecting portion 14C is a length L2 ′ obtained by adding the total expansion amount β to the initial length L2.

  Since the total expansion amounts α and β are substantially the same, the thermal stress along the tube axis direction at the joint surface between the first cylinder 13 and the second cylinder 14 can be relieved and deformation can be suppressed. It becomes possible. At the same time, the thermal stress along the tube axis direction on the joint surface between the first cylinder 13 and the target support 11 and the joint surface between the bearing cylinder 12 and the second cylinder 14 can be reduced and the deformation can be suppressed.

  In the present embodiment, the rigidity of the second cylinder 14 is reduced in design in order to absorb the difference in thermal expansion amount per unit length along the radial direction of the first cylinder 13 and the second cylinder 14. Thus, the thermal stress is absorbed by the deformation of the second cylinder 14.

  FIG. 5 is a view for explaining the state of thermal expansion along the radial direction of the first cylinder 13 and the second cylinder 14 in the configuration of the present embodiment.

  That is, in the second cylinder 14, the position along the tube axis direction of the first end portion 14 </ b> A joined to the first cylinder 13 and the tube axis direction of the second end portion 14 </ b> B joined to the bearing cylinder 12. The positions are shifted, and a connecting portion 14C is provided between them. The connecting portion 14C is formed relatively thin, has low rigidity, and has a high degree of freedom.

  As shown on the left side in the figure, when not in operation (before thermal expansion), the connecting portion 14C of the second cylinder 14 is formed in a substantially linear shape along the tube axis direction. The distance along the radial direction between the cylinder 13 is D. Then, as shown on the right side in the figure, during operation (expansion), the second cylinder 14 is deformed outwardly, that is, in a direction warping from the bearing cylinder 12 toward the first cylinder 13 due to thermal expansion. At this time, the connecting portion 14 </ b> C is deformed, and the distance D along the radial direction between the bearing cylinder 12 and the first cylinder 13 can be maintained. As a result, the stress acting in the radial direction is relieved and deformation can be suppressed.

  In addition, the first cylinder 13 is responsible for the substantial support of the anode target 4, and deformation due to thermal expansion when heat is applied is small, while the second cylinder 14 is deformed due to thermal expansion when heat is applied. Therefore, it is possible to suppress the occurrence of problems such as fatigue failure due to rotational vibration and repetitive stress due to a change in dynamic balance.

  Therefore, it becomes possible to suppress the damage accompanying the deformation between the members, and the reliability can be improved.

  Next, another structural example of this embodiment will be described.

  FIG. 6 is a cross-sectional view showing another structural example of the rotating body 10 applicable to the rotary anode X-ray tube 1 shown in FIG. Here, only the configuration necessary for the description is schematically illustrated, and the right half of the rotary anode X-ray tube 1 illustrated in FIG. 1 is illustrated in an enlarged manner. Moreover, about the structure same as the structural example demonstrated with reference to FIG. 2, the same referential mark is attached | subjected and detailed description is abbreviate | omitted.

  In the structure example shown in FIG. 6, the first end portion 14 </ b> A of the second cylinder 14 is slidably contacted with the one end portion 13 </ b> A of the first cylinder 13 as compared with the structure example shown in FIG. 2. Is different. That is, the first cylinder 13 and the second cylinder 14 are not mechanically joined to each other. Other configurations are the same as those of the structural example shown in FIG.

  The structure of each of the first cylinder 13 and the second cylinder 14 is the same as the structure example shown in FIG. That is, the first cylinder 13 includes one end 13 </ b> A joined to the target support 11 and the other end 13 </ b> B joined to the bearing cylinder 12. The second cylinder 14 includes a first end 14A including an outer peripheral surface 14O contacting the one end 13A of the first cylinder 13, a second end 14B joined to the bearing cylinder 12, and the first end 14A and the first end 14A. A connecting portion 14C that connects the two end portions 14B is provided. The second cylinder 14 having such a configuration also forms a path for conducting heat from the one end 13 </ b> A of the first cylinder 13 joined to the target support 11 to the bearing cylinder 12.

  In such a structural example, the design of the length L1 of the intermediate portion 13C of the first cylinder 13 and the length L2 of the connecting portion 14C of the second cylinder 14 is unnecessary as in the example shown in FIG. . That is, when the first cylinder 13 and the second cylinder 14 are thermally expanded along the tube axis direction, the outer peripheral surface 14O of the second cylinder 14 slides along the one end portion 13A of the first cylinder 13. For this reason, it becomes possible to absorb the difference in the amount of thermal expansion per unit length along the tube axis direction of the first cylinder 13 and the second cylinder 14, and the thermal stress between the members can be reduced and the deformation can be suppressed. It becomes possible.

  Further, when the first cylinder 13 and the second cylinder 14 are thermally expanded along the radial direction, the unit length along the radial direction of the first cylinder 13 and the second cylinder 14 is the same as in the above structural example. It is possible to absorb the difference in the amount of thermal expansion per hit. At this time, since stress acts on the first end portion 14A of the second cylinder 14 in the direction in which the first end portion 13A of the first cylinder 13 is in close contact with the first end portion 13A, the adhesion between the first cylinder 13 and the second cylinder 14 is increased. It becomes possible to promote heat conduction.

  In addition, since mechanical elasticity is further provided by providing a gap parallel to the tube axis direction in at least one of the first cylinder 13 and the second cylinder 14, when thermal expansion occurs along the radial direction, Further, the adhesion between the first cylinder 13 and the second cylinder 14 can be further improved.

  Strictly speaking, the lubricant 15 is held between the one end portion 13A of the first cylinder 13 and the outer peripheral surface 14O of the second cylinder 14. However, the thickness of the lubricant 15 is negligibly small (in FIG. 6, it is exaggerated, and the lubricant 15 forms a thick layer). In this embodiment, The one end portion 13A and the outer peripheral surface 14O are considered to be in contact or in close contact.

  The lubricant 15 is a material that can exist as a liquid or fluid having a high vapor pressure in a high vacuum, for example, any one of indium (In), gallium (Ga), tin (Sn), and silver (Ag), or , A liquid metal made of an alloy containing either of them as a main component. Such a lubricant 15 is arranged in a thickness that can be held by surface tension in the gap between the one end portion 13A and the outer peripheral surface 14O. Such a lubricant 15 can reduce the thermal resistance of the contact surface between the one end portion 13A and the outer peripheral surface 14O.

  Each of the one end portion 13A and the outer peripheral surface 14O is coated with a coating made of any of materials having low reactivity with the lubricant 15, diamond-like carbon, ceramics, molybdenum (Mo), and tungsten. Is desirable. Alternatively, the one end portion 13 </ b> A and the outer peripheral surface 14 </ b> O may be formed of ceramics having low reactivity with the lubricant 15. Thereby, reaction with the lubricant 15 on the sliding surface can be prevented.

  As described above, according to this embodiment, it is possible to provide a rotary anode X-ray tube capable of suppressing breakage due to thermal deformation between members.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit 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 anode type X-ray tube 2 ... Vacuum envelope 3 ... Cathode 4 ... Anode target 5 ... Dynamic pressure type slide bearing 6 ... Fixed body 7 ... Liquid refrigerant 10 ... Rotating body 11 ... Target support 11A ... Lower end part 12 ... Bearing Cylinder 12A ... 1st joined part 12B ... 2nd joined part 13 ... 2nd cylinder 13A ... One end part 13B ... Other end part 13C ... Intermediate | middle part 14 ... 2nd cylinder 14A ... 1st end part 14B ... 2nd end part 14C ... Connecting part 14O ... outer peripheral surface 14I ... inner peripheral surface C1 ... first notch C2 ... second notch 15 ... lubricant

Claims (14)

A cathode that emits electrons;
An anode target from which electrons emitted from the cathode are incident to emit X-rays;
A motion composed of a rotating body connected to the anode target, a columnar fixed body that rotatably supports the rotating body, and a liquid refrigerant held between the rotating body and the fixed body. A pressure-type plain bearing,
A vacuum envelope containing the anode target, the cathode, and the hydrodynamic slide bearing;
A rotary anode X-ray tube comprising:
The rotating body is formed of a target support that supports the anode target, a bearing cylinder disposed inside the target support, and a material having a thermal expansion coefficient substantially equal to that of the target support, and is joined to the target support. A first cylinder having an end and a second end joined to the bearing cylinder and forming a strength structure for supporting the anode target that receives an electron impact, and has a larger thermal expansion coefficient than the first cylinder A rotary anode type comprising: a second cylinder formed of a material and forming a path for conducting heat from the one end of the first cylinder joined to the target support to the bearing cylinder; X-ray tube. The anode target and the target support are formed of a molybdenum (Mo) alloy,
The first cylinder is made of Kovar alloy,
2. The rotary anode X-ray tube according to claim 1, wherein the second cylinder is made of copper (Cu), an alloy containing copper as a main component, or alumina-dispersed copper. The second cylinder includes an outer peripheral surface joined to the one end of the first cylinder, a first notch that forms a gap between the outer peripheral surface and the bearing cylinder, and the first cylinder A gap is formed between the inner peripheral surface joined to the bearing cylinder on the anode target side with respect to the joining position of the other end and the bearing cylinder, and the first cylinder outside the inner peripheral surface. With two notches,
The rotary anode X-ray tube according to claim 1 or 2, wherein a part of the second notch is positioned outside a part of the first notch. The second cylinder is separated from the bearing cylinder and joined to the one end of the first cylinder; and the second cylinder is separated from the first cylinder and joined to the bearing cylinder. A second end, and a connecting portion that is spaced apart from the bearing cylinder and the first cylinder and connects the first end and the second end;
The length of the connecting portion along the tube axis direction is shorter than the length along the tube axis direction between the one end portion and the other end portion of the first cylinder. The rotating anode type X-ray tube according to 2. The second cylinder protrudes toward the one end of the first cylinder and is joined to the one end, and a second end protrudes toward the bearing cylinder and joined to the bearing cylinder. The connection is separated from the bearing cylinder and the first cylinder and connects the first end and the second end and has a smaller radial thickness than the first end and the second end. And comprising
The length of the connecting portion along the tube axis direction is shorter than the length along the tube axis direction between the one end portion and the other end portion of the first cylinder. The rotating anode type X-ray tube according to 2. The second cylinder includes an outer peripheral surface that is slidably in contact with the one end portion of the first cylinder, a first notch that forms a gap between the outer peripheral surface and the bearing cylinder, Between the inner peripheral surface joined to the bearing cylinder on the anode target side from the joining position of the other end of the first cylinder and the bearing cylinder, and between the first cylinder outside the inner peripheral surface A second notch forming a void,
The rotary anode X-ray tube according to claim 1 or 2, wherein a part of the second notch is positioned outside a part of the first notch.   The second cylinder is spaced apart from the bearing cylinder and a first end including an outer peripheral surface that is slidably in contact with the one end of the first cylinder, and spaced apart from the first cylinder. And a second end joined to the bearing cylinder, and a connecting portion that is spaced apart from the bearing cylinder and the first cylinder and connects the first end and the second end. The rotary anode type X-ray tube according to claim 1 or 2, wherein   The second cylinder protrudes toward the one end of the first cylinder and includes a first end including an outer peripheral surface that is slidably in contact with the one end, and protrudes toward the bearing cylinder. A second end joined to the bearing cylinder and the first cylinder, and the first end and the second end are connected to each other, and a radial thickness is connected to the first end and the second end. The rotating anode X-ray tube according to claim 1, further comprising a connecting portion thinner than the second end portion.   9. The rotary anode X-ray tube according to claim 6, wherein at least one of the first cylinder and the second cylinder is provided with a gap parallel to the tube axis direction. 10. .   Between the one end portion of the first cylinder and the outer peripheral surface of the second cylinder, any one of indium (In), gallium (Ga), tin (Sn), and silver (Ag), or either The rotary anode X-ray tube according to any one of claims 6 to 8, wherein a lubricant made of an alloy containing the main component is held.   The rotary anode X-ray according to claim 10, wherein each of the one end portion and the outer peripheral surface is coated with diamond-like carbon, ceramics, molybdenum (Mo), or tungsten. tube.   The rotary anode X-ray tube according to claim 10, wherein the one end portion and the outer peripheral surface are made of ceramics. A cathode that emits electrons;
An anode target from which electrons emitted from the cathode are incident to emit X-rays;
A motion composed of a rotating body connected to the anode target, a columnar fixed body that rotatably supports the rotating body, and a liquid refrigerant held between the rotating body and the fixed body. A pressure-type plain bearing,
A vacuum envelope containing the anode target, the cathode, and the hydrodynamic slide bearing;
A rotary anode X-ray tube comprising:
The rotating body has a target support that supports the anode target, a bearing cylinder disposed inside the target support, one end joined to the target support, and the other end joined to the bearing cylinder. A first cylinder, and a second cylinder formed of a material having a larger coefficient of thermal expansion than the first cylinder,
The second cylinder is separated from the bearing cylinder, protrudes toward the one end of the first cylinder and is joined to the one end, and is separated from the first cylinder. A second end projecting toward the bearing cylinder and joined to the bearing cylinder, spaced apart from the bearing cylinder and the first cylinder, and connecting the first end and the second end and having a diameter. A connecting portion having a thickness in the direction thinner than the first end portion and the second end portion;
The length of the connecting portion along the tube axis direction is shorter than the length along the tube axis direction between the one end portion and the other end portion of the first cylinder. Wire tube. A cathode that emits electrons;
An anode target from which electrons emitted from the cathode are incident to emit X-rays;
A motion composed of a rotating body connected to the anode target, a columnar fixed body that rotatably supports the rotating body, and a liquid refrigerant held between the rotating body and the fixed body. A pressure-type plain bearing,
A vacuum envelope containing the anode target, the cathode, and the hydrodynamic slide bearing;
A rotary anode X-ray tube comprising:
The rotating body has a target support that supports the anode target, a bearing cylinder disposed inside the target support, one end joined to the target support, and the other end joined to the bearing cylinder. A first cylinder, and a second cylinder formed of a material having a larger coefficient of thermal expansion than the first cylinder,
The second cylinder is spaced apart from the bearing cylinder, protrudes toward the one end of the first cylinder, and slidably contacts the one end, and from the first cylinder A second end which is spaced apart and protrudes toward the bearing cylinder and is joined to the bearing cylinder; and the first end and the second end which are spaced apart from the bearing cylinder and the first cylinder And a connecting portion having a radial thickness thinner than that of the first end portion and the second end portion.

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