Rotating anode type x-ray tube

Abstract

A rotating anode type X-ray tube is provided with: an anode target; a cathode; a bearing having a rotating body and a fixed shaft, the rotating body having a cylinder portion rotatable about a rotation axis and a coupling portion provided at one end of the cylinder portion and coupled to the anode target; and a tube. The rotating body has: a solder; a first cylinder having a first inner peripheral surface including a joining surface joined to the cylinder portion via the brazing filler metal, and a second inner peripheral surface farther from the cylinder portion than the first inner peripheral surface in a direction orthogonal to the rotation axis; and a second cylinder fixed to a first outer peripheral surface of the first cylinder in a region facing the joining surface, the second cylinder being configured so that when a plane that is orthogonal to the rotational axis and passes through one end of the joining surface on the opposite side from the anode target in a direction along the rotational axis is defined as an imaginary plane, the imaginary plane is defined as the imaginary plane. The second cylinder is present on the imaginary plane.

Description

Technical Field

[0001] An embodiment of the present invention relates to a rotating anode X-ray tube. Background Art

[0002] Generally, in medical equipment and / or industrial equipment that diagnose an object using X-rays, an X-ray tube device is used as an X-ray generating source. As an X-ray tube device, a rotating anode type X-ray tube device (hereinafter also referred to as a "rotating anode type X-ray tube") is known.

[0003] The rotating anode X-ray tube device includes: a rotating anode X-ray tube that radiates X-rays; a stator coil; and a housing that accommodates the rotating anode X-ray tube and the stator coil. The rotating anode X-ray tube includes a fixed axis, a cathode that generates electrons, an anode target, a rotating body, and a tube housing. The rotating body includes a barrel and a first cylinder (copper cylinder). It is known that the first cylinder is joined to the barrel by brazing. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2-94343 Patent Document 2: Japanese Patent Application Laid-Open No. 11-213925 Summary of the invention Technical problem to be solved by the invention

[0005] This embodiment provides a rotating anode X-ray tube capable of suppressing the generation of vibration. Technical solutions adopted to solve technical problems

[0006] A rotating anode X-ray tube according to one embodiment comprises: an anode target; a cathode disposed opposite to the anode target; a bearing having a rotating body and a fixed shaft, the rotating body having a cylinder and a connecting portion, the cylinder being rotatable about a rotation axis and extending along the rotation axis to form a cylindrical shape, the connecting portion being provided at one end of the cylinder and connected to the anode target, the fixed shaft extending along the rotation axis and supporting the rotating body so as to be rotatable; and a tube shell accommodating the anode target and the cathode and fixing the fixed shaft, the rotating body having: a brazing material; a first cylinder extending along the rotation axis to form a cylindrical shape, having a first inner peripheral surface and a second inner peripheral surface. An inner circumferential surface, the first inner circumferential surface includes a joining surface joined to the cylinder portion via the brazing material, the second inner circumferential surface is adjacent to the first inner circumferential surface and is farther away from the cylinder portion than the first inner circumferential surface in a direction orthogonal to the rotation axis; and a second cylinder, which extends along the rotation axis to form a cylindrical shape and is fixed to the first outer circumferential surface of the first cylinder in an area opposite to the joining surface, when a plane orthogonal to the rotation axis and passing through one end of the joining surface is set as an imaginary plane, the second cylinder exists on the imaginary plane, and one end of the joining surface is an end of the joining surface on the opposite side of the anode target in the direction of the rotation axis.

[0007] In addition, a rotating anode X-ray tube according to one embodiment includes: an anode target; a cathode disposed opposite to the anode target; a bearing having a rotating body and a fixed shaft, the rotating body having a cylinder and a connecting portion, the cylinder being rotatable about a rotation axis and extending along the rotation axis to form a cylinder, the connecting portion being provided at one end of the cylinder and connected to the anode target, the fixed shaft extending along the rotation axis and rotatably supporting the rotating body; and a tube case accommodating the anode target and the cathode and fixing the fixed shaft, the rotating body having: a brazing material; a first cylinder extending along the rotation axis to form a cylinder, having a first inner peripheral surface and a second inner peripheral surface, the first inner peripheral surface including a joining surface joined to the cylinder via the brazing material, the second inner peripheral surface being adjacent to the first inner peripheral surface and being farther from the cylinder than the first inner peripheral surface in a direction orthogonal to the rotation axis; and a limiting portion provided on a second outer peripheral surface of the cylinder, the end surface of the first cylinder on the anode target side in the direction along the rotation axis being in contact with the limiting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional view showing the X-ray tube device according to the first embodiment. Figure 2 This is an enlarged cross-sectional view showing a part of the rotating anode X-ray tube according to the first embodiment. Figure 3This is an enlarged cross-sectional view showing a part of the rotating anode X-ray tube according to the first embodiment. Figure 4 This is an enlarged cross-sectional view showing a part of the rotating anode X-ray tube according to the first embodiment. Figure 5 This is an enlarged cross-sectional view showing a part of a rotating anode X-ray tube according to a second embodiment. Figure 6 This is an enlarged cross-sectional view showing a part of a rotating anode X-ray tube according to a third embodiment. DETAILED DESCRIPTION

[0009] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described. In addition, the disclosure is only an example, and appropriate changes that can be easily thought of by those skilled in the art while maintaining the gist of the present invention are naturally included in the scope of the present invention. In addition, in order to illustrate and explain more clearly, the width, thickness and shape of each part are sometimes schematically shown compared to the actual form, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, for the same elements as those first described in the existing figures, the same symbols are sometimes marked and the detailed description is appropriately omitted. Hereinafter, a rotating anode X-ray tube according to an embodiment will be described in detail with reference to the drawings.

[0010] (First Embodiment) Figure 1 It is a cross-sectional view showing the X-ray tube device according to the first embodiment. like Figure 1 As shown, the X-ray tube device includes: a rotating anode X-ray tube 1; a stator coil 2 as a coil for generating a magnetic field; a housing 3 accommodating the rotating anode X-ray tube 1 and the stator coil 2; and a coolant 4 filled in the housing 3.

[0011] The rotating anode X-ray tube 1 includes a bearing 30, an anode target 50, a cathode 60, a tube case 70, and a heat shield 80. The bearing 5 includes a fixed shaft 10, a rotating body 20, and a liquid metal LM as a lubricant. The fixed shaft 10 is formed in a cylindrical shape, extends along the rotation axis a, and has radial bearing surfaces S11a and S11b formed on the outer peripheral surface. The fixed shaft 10 supports the rotating body 20 so that it can rotate. The fixed shaft 10 is composed of a large diameter portion 11 and a small diameter portion 12. The large diameter portion 11 and the small diameter portion 12 are coaxially formed as a whole. The fixed shaft 10 is formed of a metal such as Fe (iron) alloy and / or Mo (molybdenum) alloy.

[0012] The large diameter portion 11 has radial bearing surfaces S11a and S11b on the outer circumference. The large diameter portion 11 has a thrust bearing surface S11i at one end and a thrust bearing surface S11j at the other end. The radial bearing surface S11a and the radial bearing surface S11b are formed over the entire outer circumference of the large diameter portion. The small diameter portion 12 is formed in a cylindrical shape having an outer diameter smaller than that of the large diameter portion 11, and is formed by extending from one end of the large diameter portion. The small diameter portion 12 is located closer to the rotation axis a than the thrust bearing surface S11i.

[0013] The rotating body 20 is configured to be rotatable around the fixed shaft 10. The rotating body 20 includes a cylinder 21, a connecting portion 22, a brazing material 23, a first cylinder 24, and a second cylinder 25. The cylinder 21 and the connecting portion 22 are respectively formed of metals such as Fe alloy and / or Mo alloy. The material of the cylinder 21 and the connecting portion 22 is, for example, an iron-nickel alloy.

[0014] The cylinder 21 extends along the rotation axis a and is formed into a cylindrical shape, and is located at a position surrounding the fixed shaft 10 (large diameter portion 11). The cylinder 21 can rotate around the rotation axis a. The cylinder 21 has uniform inner and outer diameters throughout the entire circumference, and includes a radial bearing surface S21 on the inner circumferential surface. The connection portion 22 is provided coaxially with the cylinder 21 at one end of the cylinder 21, and is connected to the anode target 50. In the first embodiment, the connection portion 22 is connected to the anode target 50 at the end on the opposite side to the cylinder 21.

[0015] The first cylinder 24 is formed into a cylindrical shape extending along the rotation axis a, and is connected to the outer peripheral surface ( Figure 2 The first cylinder 24 is formed of a metal such as copper (Cu) or a copper alloy. The second cylinder 25 is formed in a cylindrical shape and extends along the rotation axis a, and is fixed to the outer peripheral surface of the first cylinder 24 . Regarding the details of the first cylinder 24 and the second cylinder 25, Figure 2 This will be described later in the description of .

[0016] The liquid metal LM fills the gap between the fixed shaft 10 (large diameter portion 11) and the cylinder 21. The liquid metal LM can be made of materials such as GaIn (gallium indium) alloy or GaInSn (gallium indium tin) alloy. The liquid metal LM forms a dynamic pressure type sliding bearing together with the bearing surface of the fixed shaft 10 and the bearing surface of the rotating body 20. The bearing 5 is not limited to a structure that forms a dynamic pressure type sliding bearing, and may be a structure that includes a ball bearing between the fixed shaft 10 and the rotating body 20, for example.

[0017] The heat shield 80 is fixed to the rotating body 20, is formed into a cylindrical shape along the rotation axis a, and is located on the outer peripheral surface ( Figure 2 The heat shield 80 is provided at a position of the first outer peripheral surface 24a recorded in the drawings. A gap is provided between the heat shield 80 and the outer peripheral surface of the first cylinder 24. The gap can be set to about 0.5 mm, for example. The heat shield 80 blocks the radiant heat from the anode target 50 to the first cylinder 24. The heat shield 80 is formed of, for example, Kovar (KOV).

[0018] The anode target 50 is formed in an umbrella-shaped substantially disk shape and is provided coaxially with the fixed shaft 10 and the rotating body 20. The anode target 50 includes an anode target body 51 and a target layer 52 provided on a part of the outer surface of the anode target body 51.

[0019] The anode target body 51 is formed of molybdenum, tungsten, or an alloy thereof. The melting point of the metal forming the target layer 52 is the same as or higher than the melting point of the metal forming the anode target body 51. For example, the anode target body 51 is formed of a molybdenum alloy, and the target layer 52 is formed of a tungsten alloy.

[0020] The anode target 50 can rotate together with the rotating body 20. When electrons collide with the target surface S52 of the target layer 52, a focus is formed on the target surface S52. Thus, the anode target 50 emits X-rays from the focus.

[0021] The cathode 60 is spaced apart from the target layer 52 of the anode target 50 and is disposed opposite to the target layer 52. The cathode 60 is mounted on a support portion 62 fixed to the inner wall of the tube case 70. The cathode 60 has a filament 61 as an electron emission source that emits electrons to irradiate the target layer 52.

[0022] The shell 70 is formed in a cylindrical shape. The shell 70 is formed of glass, ceramics, and metal. In the shell 70, the outer diameter of the portion facing the anode target 50 is larger than the outer diameter of the portion facing the first cylinder 24. The shell 70 has an opening 71 and an X-ray transmission window 72 for transmitting X-rays. The shell 70 is sealed, accommodates the anode target 50 and the cathode 60, and fixes the fixed shaft 10. The interior of the shell 70 is maintained in a vacuum state (decompression state).

[0023] In order to maintain the airtight state of the housing 70, the opening 71 is airtightly joined to one end (small diameter portion 12) of the fixed shaft 10. The housing 70 fixes the small diameter portion 12 of the fixed shaft 10. That is, the small diameter portion 12 functions as a cantilever support portion of the bearing 5.

[0024] The stator coil 2 is provided to face the outer peripheral surface of the rotating body 20, more specifically, the outer peripheral surface of the first cylinder 24, and surround the outer side of the tube shell 70. The shape of the stator coil 2 is annular. The stator coil 2 generates a magnetic field applied to the first cylinder 24 (rotating body 20) to rotate the rotating body 20 and the anode target 50.

[0025] The housing 3 is formed in a cylindrical shape. The housing 3 is formed of a brittle material such as aluminum casting. A lead plate for shielding X-rays is attached to the inner surface of the housing 3. The housing 3 has a support portion 3a that supports the rotating anode X-ray tube 1 and the stator coil 2.

[0026] The coolant 4 is filled in the space between the rotating anode X-ray tube 1 and the housing 3. The coolant 4 can use insulating oil or water-based coolant. As described above, the X-ray tube device including the rotating anode X-ray tube 1 is formed.

[0027] In the operating state of the above-mentioned X-ray tube device, the stator coil 2 generates a magnetic field applied to the rotating body 20 (particularly the first cylinder 24), so the cylinder 21 rotates. As a result, the anode target 50 also rotates. In addition, a current is applied to the cathode 60 and a negative voltage is applied, and a positive voltage is applied to the anode target 50 relatively.

[0028] As a result, a potential difference is generated between the cathode 60 and the anode target 50. The filament 61 emits electrons. The electrons are accelerated and collide with the target surface S52. As a result, a focus is formed on the target surface S52, and the focus emits X-rays when colliding with the electrons. The electrons (thermal electrons) that collide with the anode target 50 are converted into X-rays, and the rest are converted into thermal energy. In addition, the electron emission source of the cathode 60 is not limited to the filament, and it can also be a planar emitter, for example.

[0029] The heat generated by the anode target 50 is transferred from the target surface S52 to the inside of the target layer 52, the anode target body 51, the connecting portion 22, the cylinder 21, the brazing material 23, the first cylinder 24, and the second cylinder 25. In the case where the second cylinder 25 is not provided, the first cylinder 24 is deformed in shape and peeled off from the cylinder 21 by repeating the above-mentioned heat transfer and natural cooling when the X-ray tube device is not used.

[0030] Figure 2 This is an enlarged cross-sectional view showing a part of the rotating anode X-ray tube according to the first embodiment. like Figure 2 As shown, the rotating body 20 includes a cylindrical portion 21, a connecting portion 22, a brazing material 23, a first cylinder 24, and a second cylinder 25. In addition, a heat shielding plate 80 is fixed to the rotating body 20.

[0031] The first cylinder has a first outer peripheral surface 24a, a first inner peripheral surface 24b, and a second inner peripheral surface 24c. The first outer peripheral surface 24a is opposite to the heat shield 80. The first inner peripheral surface 24b includes a joint surface 26 that is joined to the second outer peripheral surface 21a of the cylinder 21 via the brazing material 23. That is, the joining method between the cylinder 21 and the first cylinder 24 is brazing. In addition, in the first embodiment, the first inner peripheral surface 24b is located between the second inner peripheral surface 24c and the anode target 50 in the direction along the rotation axis a.

[0032] In the first embodiment, the first outer peripheral surface 24a is composed of a large outer peripheral surface 24a1 and a small outer peripheral surface 24a2. The small outer peripheral surface 24a2 is located closer to the rotation axis a than the large outer peripheral surface 24a1 in the direction orthogonal to the rotation axis a. In addition, the first outer peripheral surface 24a may not be composed of the large outer peripheral surface 24a1 and the small outer peripheral surface 24a2, but may be an outer peripheral surface having only one outer diameter centered on the rotation axis a.

[0033] The second inner circumferential surface 24c is adjacent to the first inner circumferential surface 24b and is farther from the cylinder 21 than the first inner circumferential surface 24b in the direction orthogonal to the rotation axis a. The first cylinder 24 suppresses heat conduction from the first cylinder 24 to the cylinder 21 through a gap (second gap) between the second inner circumferential surface 24c and the second outer circumferential surface 21a of the cylinder 21, thereby protecting the bearing surface of the rotating body 20 and the bearing surface of the fixed shaft 10.

[0034] The second cylinder 25 is fixed to the first outer peripheral surface 24a of the first cylinder 24, is continuous in the circumferential direction around the rotation axis a and is formed in an annular shape, and has a third outer peripheral surface 25a. The thermal expansion coefficient of the second cylinder 25 is smaller than the expansion coefficient of the first cylinder 24. In addition, the rigidity of the second cylinder 25 is greater than the rigidity of the first cylinder 24. The material of the second cylinder 25 is, for example, an iron-based material. The second cylinder 25 is located in a region opposite to the joint surface 26 in a direction perpendicular to the rotation axis a. In the first embodiment, the second cylinder 25 is fixed to the small outer peripheral surface 24a2 of the first outer peripheral surface 24a. The third outer peripheral surface 25a of the second cylinder 25 is located closer to the rotation axis a side than the large outer peripheral surface 24a1 in a direction perpendicular to the rotation axis a.

[0035] In addition, when the first outer peripheral surface 24a is not composed of the large outer peripheral surface 24a1 and the small outer peripheral surface 24a2, for example, when the first outer peripheral surface 24a is an outer peripheral surface having only one outer diameter centered on the rotation axis a, the second cylinder 25 is fixed to the first outer peripheral surface 24a. In this case, the third outer peripheral surface 25a of the second cylinder 25 is located farther from the rotation axis a than the first outer peripheral surface 24a of the first cylinder 24 in the direction orthogonal to the rotation axis a than the first cylinder 24. The fixing method of the second cylinder 25 is, for example, diffusion bonding performed under a temperature condition lower than the melting point of the first cylinder 24.

[0036] The heat shield 80 is formed in a cylindrical shape and has an upper end 81, a connecting portion 82, and a contact avoiding portion 83. The upper end 81 is the end of the heat shield 80 on the anode target 50 side along the direction of the rotation axis a. The connecting portion 82 connects the upper end 81 and the contact avoiding portion 83. The contact avoiding portion 83 is continuously formed with a curve in a direction away from the first outer peripheral surface 24a over the entire circumference. The so-called direction away from the first outer peripheral surface 24a is a direction orthogonal to the rotation axis a and away from the rotation axis a. In the first embodiment, the cross-sectional shape of the curve of the contact avoiding portion 83 is an arc shape.

[0037] The heat shield 80 is fixed to the rotating body 20. More specifically, the upper end 81 of the heat shield 80 is fixed to the connecting portion 22 of the rotating body 20. The heat shield 80 and the rotating body 20 are fixed by, for example, fastening with screws. In addition, the position where the heat shield 80 is fixed is not limited to the connecting portion 22, and may be fixed to, for example, the second outer peripheral surface 21a of the cylinder 21.

[0038] Next, the positional relationship between the brazing material 23 and the second cylinder 25 will be described. In the first embodiment, if the gap between the first inner peripheral surface 24b of the first cylinder 24 and the second outer peripheral surface 21a of the cylinder portion 21 is defined as the first gap G1, the brazing material 23 is provided in the first gap G1. Hereinafter, the portion of the first inner peripheral surface 24b fixed to the second outer peripheral surface 21a by the brazing material 23 is referred to as a bonding surface 26.

[0039] The second cylinder 25 exists on a virtual plane S1 that is perpendicular to the rotation axis a and passes through the end of the joint surface 26 opposite to the anode target 50 along the rotation axis a. In other words, the second cylinder 25 is located at a position that passes through the virtual plane S1.

[0040] Next, the positional relationship between the brazing material 23 and the contact avoiding portion 83 of the heat shield plate 80 will be described. The contact avoiding portion 83 exists on the virtual plane S1. In other words, the contact avoiding portion 83 is located at a position penetrating the virtual plane S1.

[0041] exist Figure 2 In the description of FIG. 1 , the case where the one end 23a of the solder 23 is accommodated in the first gap G1 is described. The one end 23a of the solder 23 is the one end 23a on the opposite side of the anode target 50 along the direction of the rotation axis a of the solder 23. Figure 3 and Figure 4 , a case where the one end 23a of the brazing material 23 is not accommodated in the first gap G1 is described.

[0042] Figure 3 FIG. 2 is an enlarged cross-sectional view showing a portion of the rotating anode X-ray tube according to the first embodiment. Figure 3 As shown in the figure, when the gap between the second inner peripheral surface 24c of the first cylinder 24 and the second outer peripheral surface 21a of the cylinder 21 is set as the second gap, and the plane passing through the boundary between the first gap G1 and the second gap G2 and being orthogonal to the rotation axis a is set as the boundary surface, the end 23a of the brazing material 23 on the opposite side of the anode target 50 in the direction of the rotation axis a is located on the boundary surface S2. At this time, the virtual plane S1 and the boundary surface S2 are located on the same plane. The second cylinder 25 and the contact avoiding portion 83 exist on the virtual plane S1 including the boundary surface S2.

[0043] Figure 4 FIG. 2 is an enlarged cross-sectional view showing a portion of the rotating anode X-ray tube according to the first embodiment. Figure 4 As shown, one end 23a of the brazing material 23 on the opposite side of the anode target 50 along the rotation axis a is located in the second gap G2. At this time, the virtual plane S1 and the boundary surface S2 are located on the same plane. The second cylinder 25 and the contact avoiding portion 83 exist on the virtual plane S1 including the boundary surface S2.

[0044] Summarizing the relationship between the solder 23 and the imaginary plane S1, Figure 3 and Figure 4 As shown, one end 23a of the solder 23 is located at the boundary surface S2 or in the second gap G2. At this time, the imaginary plane S1 and the boundary surface S2 are located on the same plane.

[0045] The effects of the first embodiment will be described. According to the rotating anode X-ray tube 1 of the first embodiment configured as described above, the rotating anode X-ray tube 1 includes: an anode target 50; a cathode 60; a bearing 5 having a fixed shaft 10 and a rotating body 20; and a tube shell 70. The rotating body 20 includes: a cylinder 21; a brazing material 23; a first cylinder 24 joined to the cylinder 21 via the brazing material 23; and a second cylinder 25 fixed to the outer peripheral surface of the first cylinder 24. The second cylinder 25 exists on the imaginary plane S1 (refer to Figure 2 ). When the one end 23 a of the solder 23 is located in the boundary surface S2 or the second gap G2 , the imaginary plane S1 and the boundary surface S2 are located on the same plane. The second cylinder 25 is formed in an annular shape continuously in the circumferential direction around the rotation axis a. The thermal expansion coefficient of the second cylinder 25 is smaller than that of the first cylinder 24 .

[0046] Thus, it is possible to suppress the first cylinder 24 from peeling off from the cylinder portion 21 due to the repetition of the heat generated when the anode target 50 generates X-rays and the natural cooling when the rotary anode type X-ray tube 1 is not used. That is, it is possible to obtain a rotary anode type X-ray tube in which the vibration caused by the eccentricity of the rotary body 20 relative to the rotation axis a due to the peeling of the first cylinder 24 when the rotary body 20 rotates can be suppressed. In addition, it was confirmed that the deformation amount of the first cylinder 24 in the direction orthogonal to the rotation axis a was approximately one-fourth of that in the case where the second cylinder 25 was not provided.

[0047] The rotating anode X-ray tube 1 further includes a heat shield 80 which is fixed to the rotating body 20 and blocks the radiant heat from the anode target 50 to the first cylinder 24. The heat shield 80 has a contact avoidance portion 83 which is continuously curved along the entire circumference in a direction away from the first outer peripheral surface 24a. The contact avoidance portion 83 exists on the imaginary plane S1 (see Figure 2 ). The first outer peripheral surface 24a is composed of a large outer peripheral surface 24a1 and a small outer peripheral surface 24a2, and the second cylinder 25 is located on the small outer peripheral surface 24a2. The third outer peripheral surface 25a of the second cylinder 25 is located closer to the rotation axis a than the large outer peripheral surface 24a1. This can suppress the first cylinder 24 from coming into contact with the heat shielding plate 80. Specifically, it can suppress an increase in vibration caused by the first cylinder 24 coming into contact with the heat shielding plate 80 when the rotating body 20 rotates.

[0048] (Second Embodiment) Next, a rotary anode X-ray tube 1 according to a second embodiment will be described. The rotary anode X-ray tube 1 is configured similarly to the first embodiment except for the configuration described in the second embodiment. Figure 5 This is an enlarged cross-sectional view showing a part of a rotating anode X-ray tube according to a second embodiment.

[0049] like Figure 5 As shown, the rotating body 20 also has a limiting portion 27, which is provided on the second outer peripheral surface 21a of the barrel 21. The rigidity of the limiting portion 27 is higher than that of the first cylinder 24. In the second embodiment, the limiting portion 27 is continuously formed as a whole with the barrel 21. In addition, the limiting portion 27 may not be continuously formed as a whole with the barrel 21, for example, it may be joined to the second outer peripheral surface 21a of the barrel 21. The limiting portion 27 contacts the end surface 24e of the first cylinder 24 on the anode target side in the direction along the rotation axis a. In addition, in the second embodiment, the limiting portion 27 is opposite to the end surface 25b of the second cylinder 25 on the anode target 50 side in the direction along the rotation axis a.

[0050] According to the rotary anode X-ray tube 1 of the second embodiment configured as above, the rotating body 20 further includes a restricting portion 27. The end surface 24e of the first cylinder 24 contacts the restricting portion 27. In addition, as described above, the rigidity of the restricting portion 27 is higher than that of the first cylinder 24. Therefore, when the first cylinder 24 itself is to be deformed (expanded) toward the restricting portion 27, the restricting portion 27 plays a function of pressing the first cylinder 24 against the member (cylindrical portion 21) constituting the inner side of the first cylinder 24. Since the deformation of the first cylinder 24 can be suppressed, the first cylinder 24 can be suppressed from being peeled off from the cylinder 21.

[0051] The restricting portion 27 faces the end surface 25b of the second cylinder 25. Thus, the second cylinder 25 can be prevented from being separated from the first cylinder 24.

[0052] (Third Embodiment) Next, a rotary anode X-ray tube 1 according to a second embodiment will be described. The rotary anode X-ray tube 1 is configured similarly to the second embodiment except for the configuration described in the third embodiment. Figure 6 This is an enlarged cross-sectional view showing a part of a rotating anode X-ray tube according to a third embodiment.

[0053] like Figure 6 As shown, the rotating body 20 is configured without the second cylinder 25. The first outer peripheral surface 24a of the first cylinder 24 is not composed of the large outer peripheral surface 24a1 and the small outer peripheral surface 24a2. The first outer peripheral surface 24a is an outer peripheral surface having only one outer diameter centered on the rotation axis a. The restricting portion 27 contacts the end surface 24e of the first cylinder 24.

[0054] According to the rotary anode X-ray tube 1 of the third embodiment configured as described above, it is possible to obtain the same effects as those of the rotary anode X-ray tube of the first embodiment.

[0055] Several embodiments of the present invention are described above, but these embodiments are only examples and do not limit the scope of the invention. These new embodiments can also be implemented in various other ways, and can be omitted, replaced, changed, etc. without departing from the scope of the invention. These embodiments and their modifications are included in the scope or purpose of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A rotating anode X-ray tube, characterized in that: have: Anode target; a cathode disposed opposite to the anode target; A bearing having a rotating body and a fixed shaft, wherein the rotating body has a cylindrical portion and a connecting portion, wherein the cylindrical portion is rotatable about a rotation axis and extends along the rotation axis to form a cylindrical shape, wherein the connecting portion is provided at one end of the cylindrical portion and is connected to the anode target, and wherein the fixed shaft extends along the rotation axis and rotatably supports the rotating body; and a tube shell, which accommodates the anode target and the cathode and fixes the fixed axis, The rotating body has: Brazing filler metal; a first cylinder extending along the rotation axis to be formed into a cylindrical shape, having a first inner peripheral surface and a second inner peripheral surface, the first inner peripheral surface including a joint surface joined to the cylinder portion via the brazing material, the second inner peripheral surface being adjacent to the first inner peripheral surface and being farther from the cylinder portion than the first inner peripheral surface in a direction orthogonal to the rotation axis; as well as a second cylinder extending along the rotation axis to be formed into a cylindrical shape and fixed to a first outer peripheral surface of the first cylinder in a region opposite to the joint surface; The second cylinder exists on a virtual plane that is orthogonal to the rotation axis and passes through one end of the joint surface, and the one end of the joint surface is an end of the joint surface on the opposite side of the anode target in the direction along the rotation axis.

2. The rotating anode X-ray tube according to claim 1, characterized in that: The gap between the first inner peripheral surface and the second outer peripheral surface of the tube portion is set as a first gap, The gap between the second inner peripheral surface and the second outer peripheral surface is set as a second gap, When a plane passing through a boundary between the first gap and the second gap and being orthogonal to the rotation axis is set as a boundary plane, One end of the brazing material on the opposite side to the anode target in the direction along the rotation axis is located at a boundary surface between the first gap and the second gap, or is located at the second gap. The imaginary plane and the boundary surface are located on the same plane.

3. The rotating anode X-ray tube according to claim 2, characterized in that: The second cylinder is formed in an annular shape continuously in a circumferential direction around the rotation axis.

4. The rotating anode X-ray tube according to claim 1, characterized in that: The second cylinder is formed in an annular shape continuously in a circumferential direction around the rotation axis.

5. The rotating anode X-ray tube according to claim 4, characterized in that: The second cylinder has a smaller thermal expansion coefficient than the first cylinder.

6. The rotating anode X-ray tube according to claim 1, characterized in that: The rotating body has a limiting portion provided on the second outer peripheral surface of the cylindrical portion, An end surface of the first cylinder on the anode target side in the direction along the rotation axis is in contact with the restricting portion.

7. The rotating anode X-ray tube according to claim 6, characterized in that: A heat shield is further provided, which is fixed to the rotating body, is formed in a cylindrical shape along the rotation axis, surrounds the first outer peripheral surface, and shields the radiant heat from the anode target to the first cylinder. The first inner circumferential surface is located between the second inner circumferential surface and the anode target in the direction along the rotation axis. The heat insulation board has a contact avoiding portion, the contact avoiding portion being continuously curved along the entire circumference in a direction away from the first outer peripheral surface. The contact avoiding portion exists on the imaginary plane.

8. The rotating anode X-ray tube according to claim 1, characterized in that: A heat shield is further provided, which is fixed to the rotating body, is formed in a cylindrical shape along the rotation axis, surrounds the first outer peripheral surface, and shields the radiant heat from the anode target to the first cylinder. The first inner circumferential surface is located between the second inner circumferential surface and the anode target in the direction along the rotation axis. The heat insulation board has a contact avoiding portion, the contact avoiding portion being continuously curved along the entire circumference in a direction away from the first outer peripheral surface. The contact avoiding portion exists on the imaginary plane.

9. The rotating anode X-ray tube according to claim 8, characterized in that: The first outer peripheral surface is composed of a large outer peripheral surface and a small outer peripheral surface, and the small outer peripheral surface is located closer to the rotation axis than the large outer peripheral surface. The second cylinder is fixed to the small outer peripheral surface, The third outer peripheral surface of the second cylinder is located closer to the rotation axis than the large outer peripheral surface.

10. A rotating anode X-ray tube, characterized in that: have: Anode target; a cathode disposed opposite to the anode target; A bearing having a rotating body and a fixed shaft, wherein the rotating body has a cylindrical portion and a connecting portion, wherein the cylindrical portion is rotatable about a rotation axis and extends along the rotation axis to form a cylindrical shape, wherein the connecting portion is provided at one end of the cylindrical portion and is connected to the anode target, and wherein the fixed shaft extends along the rotation axis and rotatably supports the rotating body; and a tube shell, which accommodates the anode target and the cathode and fixes the fixed axis, The rotating body has: Brazing filler metal; a first cylinder extending along the rotation axis to be formed into a cylindrical shape, having a first inner peripheral surface and a second inner peripheral surface, the first inner peripheral surface including a joint surface joined to the cylinder portion via the brazing material, the second inner peripheral surface being adjacent to the first inner peripheral surface and being farther from the cylinder portion than the first inner peripheral surface in a direction orthogonal to the rotation axis; as well as a limiting portion, which is provided on the second outer peripheral surface of the tube portion, An end surface of the first cylinder on the anode target side in the direction along the rotation axis is in contact with the restricting portion.

11. The rotating anode X-ray tube according to claim 10, characterized in that: The restricting portion has higher rigidity than the first cylinder.

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