A tube core assembly and tube shell manufacturing method for improving the heat dissipation performance of an X-ray tube

Abstract

The invention discloses a tube core assembly and a tube shell manufacturing method for improving the heat dissipation performance of an X-ray tube, comprising a cathode assembly, a shell assembly connected to the cathode assembly, and an anode assembly located in the shell assembly and rotating along the axial direction of the shell assembly, characterized in that the shell assembly comprises a tube shell, a plurality of heat dissipation strips are arranged on the inner wall of the tube shell, and the plurality of heat dissipation strips surround the anode assembly in the middle of the tube shell; the manufacturing method of the shell assembly comprises the following steps: step 1, selecting a heat dissipation strip length matching the height of the tube shell; step 2, using a milling cutter to mill out a welding groove in the length direction of the back of the heat dissipation strip; step 3, placing solder in the welding groove and fixing it with a tool; step 4, placing the tube shell in a vacuum furnace or a hydrogen furnace, heating to 800-1200°C, melting the solder, and using the capillary effect to evenly spread the solder in the gap between the heat dissipation strip and the inner wall of the tube shell; step 5, after cooling, roughening the inner surface of the tube shell.

Description

Technical Field

[0001] The present invention relates to the application field of X-ray tube technology, and in particular to a tube core component and a tube shell manufacturing method for improving the heat dissipation performance of an X-ray tube. Background Art

[0002] The hot cathode of the X-ray tube generates free electrons. Under the action of high voltage, the electrons obtain 120-160kV energy and bombard the anode target to generate X-rays, of which 99% of the energy is converted into heat energy, and only 1% is converted into X-rays to radiate toward the window. In the actual operation of the X-ray tube, the emission current is usually in the order of hundreds of milliamperes, and the corresponding thermal power is tens of kilowatts.

[0003] Traditional X-ray tubes use radiation heat exchange to achieve heat exchange between the anode target and the shell. For X-ray tubes with glass shells, the thermal radiation coefficient of glass is about 0.9, and efficient radiation heat exchange can be achieved without special process treatment, but the disadvantage of the glass shell is that it is not rigid and easy to break. For the current mainstream metal shell, it is usually made of stainless steel and has good mechanical properties, but the thermal radiation coefficient of metal is only 0.01-0.1, which cannot achieve efficient heat exchange. For this reason, the shell is usually blackened to improve its radiation heat transfer coefficient.

[0004] Traditional X-ray tube black coating is aluminum nitride or Fe304, and the radiation coefficient can be increased to 0.85-0.9, which is close to the glass shell. However, practice shows that since the temperature of the shell reaches 200-400℃ during the operation of the X-ray tube, the black layer on the shell surface may fall off, which will cause ignition inside the X-ray tube, and the entire CT machine is forced to shut down, which seriously affects its efficiency.

[0005] In the prior art, the patent name is "A preparation method and application of Fe304 coating for improving thermal radiation coefficient", and the patent number is ZL111153440A. It proposes a double-layer coating, the surface layer is Fe304, the inner layer is Fe304-TiO2 composite material, and the Fe304-TiO2 mixed powder is obtained by co-precipitation, modification, mixing and other methods, and then the electron beam physical vapor deposition method is used to plate a 10μm Fe304-TiO2 coating on the surface of the tube shell. After curing, a 1mm thick Fe304 surface coating is obtained under the action of an external magnetic field. After the above complex process, the double-layer coating is plated on the inner surface of the tube shell to avoid the problem of coating shedding, and its radiation coefficient is nominally 0.94-0.95.

[0006] The existing method of using spraying to blacken the inside of the metal shell of the X-ray tube can significantly enhance the radiation heat transfer coefficient, but it also brings hidden dangers to the stable operation of the X-ray tube. Practice has shown that a considerable proportion of scrapped tube cores are caused by sparks due to the shedding of the black layer on the surface of the tube shell. Since the coating involves PVD coating process, parameters such as temperature, vacuum, voltage, film thickness and target size during the coating process will affect the coating quality, introducing a potential risk of sparks to the tube core.

[0007] Since X-ray tubes operate under high temperature, high pressure, high vacuum, centrifugal loads of 10g or more, and ionizing radiation environments, most coating manufacturers do not have coating experience with this type of special equipment. It is a long process to explore the coating parameters. In addition, the parameters also need to be adjusted for different tube shell sizes and different coating environments, which also poses a hidden danger to the stability of the product. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a tube core assembly for improving the heat dissipation performance of an X-ray tube. The heat dissipation performance of the X-ray tube is improved by brazing a heat dissipation strip on the inner wall of a metal tube shell and then roughening the surface of the inner wall of the tube shell. In addition, since no coating material is introduced, the problem of internal ignition of the tube core caused by coating shedding is fundamentally avoided. Moreover, the process steps are easier to control than the coating process, thereby improving the stability of the operation of the X-ray tube.

[0009] The technical solution of the present invention is: a tube core assembly for improving the heat dissipation performance of an X-ray tube, comprising a cathode assembly, a shell assembly connected to the cathode assembly, and an anode assembly located in the shell assembly and rotating along the axial direction of the shell assembly, wherein the shell assembly comprises a tube shell, and a plurality of heat dissipation strips are arranged on the inner wall of the tube shell, and the plurality of heat dissipation strips enclose the anode assembly in the middle of the tube shell;

[0010] When the cathode assembly emits electron beams to the anode assembly, heat is dissipated inside the shell assembly through the tube shell and the heat dissipation strips.

[0011] Furthermore, the cross section of the heat dissipation strip is a perfect semicircle or ellipse structure.

[0012] Furthermore, the radiation heat dissipation angle of the heat dissipation strip is 177°.

[0013] Furthermore, the heat dissipation strips are welded to the inner wall of the tube shell in an aligned manner along the axial curved surface of the tube shell.

[0014] Furthermore, a welding groove is provided on the back of the heat dissipation bar close to the inner wall of the tube shell, and solder is provided in the welding groove, and the heat dissipation bar is welded to the inner wall of the tube shell through the solder.

[0015] Furthermore, there are 24 heat dissipation strips.

[0016] Furthermore, the angle between adjacent heat dissipation strips is 15°.

[0017] A tube shell manufacturing method comprises the following steps:

[0018] Step 1. Select the heat sink length that matches the tube shell height;

[0019] Step 2: Use a milling cutter to mill out a welding groove in the length direction of the back of the heat sink. The width and height of the welding groove are 1mm*1mm or 0.5mm*0.5mm respectively, and the length of the welding groove is equal to the length of the heat sink.

[0020] The fitting curved surface of the heat dissipation strip is the same as the inner wall curved surface of the tube shell;

[0021] Step 3: Place the solder in the soldering tank and fix it with a tool;

[0022] Step 4: Place the tube shell in a vacuum furnace or hydrogen furnace and heat it to 800-1200°C to melt the solder. Using the capillary effect, the solder is evenly spread in the gap between the heat dissipation strip and the inner wall of the tube shell.

[0023] Step 5: After cooling, the inner surface of the tube shell is roughened.

[0024] Furthermore, in step 1, the tube shell and the heat sink are made of oxygen-free copper or dispersed copper material, so that the thermal expansion of the tube shell and the heat sink is the same.

[0025] Furthermore, in step 5, the roughening is performed by sandblasting or laser irradiation.

[0026] The beneficial technical effects of the present invention are:

[0027] 1. The heat dissipation strip adopts a curved array with surface roughening to process the metal shell of the X-ray tube, which improves the heat dissipation efficiency of the X-ray tube and fundamentally solves the problem of coating shedding, greatly improving the stability of the equipment.

[0028] 2. The cross-section of the heat dissipation strip is a semicircular or elliptical structure. By utilizing the effect of the radiation angle, multiple reflection superpositions are achieved when the target plate and the tube shell are heat exchanged. Combined with the surface roughening process, its heat dissipation effect is better than the traditional Fe304 coating process. Simulation shows that the maximum temperature of the anode target plate has dropped by 10%-15%.

[0029] 3. The use of brazing curved surface array instead of traditional spraying process greatly reduces the cost and reduces the risk of core ignition caused by coating shedding.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0033] Figure 3 A top view of the internal structure of the housing assembly of the present invention;

[0034] Figure 4 is a cross-sectional view of the internal structure of the housing assembly of the present invention;

[0035] Figure 5 is a schematic diagram of a curved array of heat dissipation strips of the present invention;

[0036] Figure 6 It is a schematic structural diagram of the heat dissipation strip of the present invention;

[0037] Figure 7 Another perspective of the structural schematic diagram of the heat dissipation strip of the present invention;

[0038] Figure 8 This is a temperature rise simulation diagram of the spraying process with a radiation coefficient of 0.88 inside the shell;

[0039] Fig. 9 Schematic diagram of the heat distribution of the target disk in the heat dissipation strip curved array solution;

[0040] Fig.10 Schematic diagram of the overall heat distribution of the shell assembly.

[0041] The accompanying drawings are marked as follows:

[0042] 100, cathode assembly; 110, cathode electron gun; 200, shell assembly; 210, tube shell; 220, heat sink; 221, welding groove; 222, solder; 300, bearing assembly; 400, target assembly. DETAILED DESCRIPTION

[0043] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0044] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so as to describe the embodiments of the present application described herein.

[0045] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships described in the embodiments and shown in the accompanying drawings, or are directions or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0046] like Figure 1-Figure 7 As shown, the present invention specifically relates to a tube core assembly for improving the heat dissipation performance of an X-ray tube, comprising a cathode assembly 100, a shell assembly 200 connected to the cathode assembly 100, and an anode assembly located in the shell assembly 200 and rotating along the axial direction of the shell assembly 200, wherein the shell assembly 200 comprises a tube shell 210, wherein a plurality of heat dissipation bars 220 are arranged on the inner wall of the tube shell 210, and the plurality of heat dissipation bars 220 enclose the anode assembly in the middle of the tube shell 210;

[0047] When the cathode assembly 100 emits electron beams relative to the anode assembly, heat is dissipated inside the housing assembly 200 through the tube shell 210 and the heat dissipation bar 220 .

[0048] It should be noted that the role of the tube core assembly in the X-ray tube in this embodiment is consistent with that in the prior art. The cathode assembly 100 includes a cathode head and a cathode electron gun 110 disposed in the cathode head; the anode assembly is disposed in the housing assembly 200 through a bearing assembly 300 and can rotate relative to the inside of the housing assembly 200 along the axial direction of the bearing assembly 300; the anode assembly includes a target disk assembly 400, and the target disk assembly 400 is composed of a TZM target disk and a graphite target disk;

[0049] During the operation of the X-ray tube, the electron beam emitted by the cathode electron gun 110 bombards the target disk assembly, thereby generating heat. The main physical process of heat transfer includes: the electron beam bombards the target disk, 1% of the beam power is converted into X-rays for imaging; 99% is converted into heat and deposited on the target disk assembly 400, and the temperature of the TZM target disk and the graphite target disk increases. The TZM alloy and graphite are radiated to the tube shell 210 to heat the tube shell 210. The tube shell 210 is a copper shell, and after heat conduction, convection heat is transferred to the insulating oil outside the tube shell 210 to achieve heat exchange.

[0050] By arranging a plurality of heat dissipation bars 220 in the tube shell 210 , the plurality of heat dissipation bars 220 enclose the target plate assembly 400 in the middle of the tube shell 210 , thereby increasing the contact area and improving the heat dissipation performance.

[0051] like Figure 5-Figure 7 As shown, the cross section of the heat dissipation bar 220 is a perfect semicircle or ellipse structure, and the radiation heat dissipation angle of the heat dissipation bar 220 is 177°.

[0052] This not only ensures that the heat dissipation strip 220 is closely attached to the inner wall of the tube shell 210 , but also improves the diffuse reflection capability of infrared electromagnetic waves.

[0053] The heat dissipation bars 220 are aligned along the axial curved surface of the tube shell 210 and welded to the inner wall of the tube shell 210 .

[0054] A welding groove 221 is provided at the back of the heat dissipation bar 220 close to the inner wall of the tube shell 210 . Solder 222 is provided in the welding groove 221 . The heat dissipation bar 220 is welded to the inner wall of the tube shell 210 through the solder 222 .

[0055] It should be noted that the cross-section of the solder 222 is circular, and the material is pure copper, silver copper or gold copper solder 222, utilizing the good ductility of the copper material; in addition, the heat sink 220 and the tube shell 210 are both made of oxygen-free copper or dispersed copper material, ensuring that the thermal expansion of the tube shell 210 and the heat sink 220 is the same, which can effectively avoid cracking of the weld caused by thermal expansion of the tube shell 210.

[0056] like Figure 4 and Figure 5 As shown, there are 24 heat dissipation bars 220 , the angle between adjacent heat dissipation bars 220 is 15°, and the 24 heat dissipation bars 220 are evenly distributed along the circumference of the tube shell 210 .

[0057] For example:

[0058] The diameter of the tube shell 210 is 160-200mm, and the height of the tube shell 210 is 100-130mm. It uses oxygen-free copper or dispersed copper materials. Its physical characteristics include excellent thermal conductivity of 400W / (m*K), which is conducive to the rapid heat dissipation. The material has low oxygen content inside, and the outgassing rate of the copper material is less than 10 after proper baking. -10 Pa*m 3 / s, which is beneficial for X-ray tubes to operate at a speed better than 10 -6 Pa operates stably under high vacuum.

[0059] The heat dissipation strip 220 uses the same copper material as the tube shell 210 to avoid cracking of the weld due to thermal expansion of the tube shell 210 when the X-ray tube is running. The theoretical basis is as follows: the linear expansion coefficient of oxygen-free copper and dispersed copper is about 1.68*10 -5 m / (m*K). Experiments show that in the working state, the temperature of the tube shell 210 reaches 80-100°C. Taking the tube shell 210 with a diameter of 200mm as an example, when heated from room temperature 25°C to the rated working temperature, the tube shell 210 expands 200*1.68*10 in the radial direction. -5 * (100-25) = 0.25 mm. By utilizing the good ductility of copper and using a curved array of heat dissipation bars 220, the thermal expansion of the tube shell 210 and the heat dissipation bars 220 are made the same, which can effectively prevent the tube shell 210 from causing weld cracking during thermal expansion.

[0060] 24 heat sinks 220 are evenly distributed along the circumference of the tube shell 210, and the angle between adjacent arrays is 15°. A welding groove 221 is set on the back of each curved array. The length L of the heat sink 220 matches the height of the tube shell 210, preferably 70-95mm, and a milling cutter is used to mill out the welding groove 221 in the length direction. The width and height of the welding groove 221 are 1mm*1mm or 0.5mm*0.5mm respectively. The fitting curved surface of the heat sink 220 is the same as the inner wall curved surface of the tube shell 210, ensuring that the curved heat sink array and the inside of the tube shell 210 fit well. The cross-sectional shape is a quasi-fan-shaped structure, and the radius of curvature R2 of the arc of the cross section of the heat sink 220 is 4-8mm. The radiation heat dissipation angle is 177°, which improves the diffuse reflection ability of infrared electromagnetic waves. When there is no curved heat sink array, the inner wall area of ​​the tube shell 210 is 51649mm 2 After setting 24 curved heat dissipation arrays, the inner wall area of ​​the tube shell 210 is 61057mm 2 , the inner wall area is increased by 18% compared to when there is no heat dissipation surface.

[0061] A tube shell manufacturing method comprises the following steps:

[0062] Step 1, selecting the length of the heat dissipation bar 220 that matches the height of the tube shell 210;

[0063] In step 1, the tube shell 210 and the heat dissipation bar 220 are made of oxygen-free copper or dispersed copper material, so that the tube shell 210 and the heat dissipation bar 220 have the same thermal expansion.

[0064] Step 2: Use a milling cutter to mill out a welding groove 221 in the length direction of the back of the heat dissipation bar 220. The width and height of the welding groove 221 are 1 mm*1 mm or 0.5 mm*0.5 mm respectively, and the length of the welding groove 221 is equal to the length of the heat dissipation bar 220.

[0065] The fitting curved surface of the heat dissipation strip 220 is the same as the inner wall curved surface of the tube shell 210;

[0066] Step 3, placing the solder 222 in the soldering groove 221 and fixing it with a tool;

[0067] Step 4: Place the tube shell 210 in a vacuum furnace or a hydrogen furnace and heat it to 800-1200° C. to melt the solder 222. By using the capillary effect, the solder 222 is evenly spread in the gap between the heat dissipation bar 220 and the inner wall of the tube shell 210.

[0068] Step 5: After cooling, the inner surface of the tube shell 210 is roughened.

[0069] In step 5, the roughening is performed by sandblasting or laser irradiation.

[0070] The above-mentioned method of brazing the heat dissipation strip 220 is adopted to improve the heat dissipation performance of the X-ray tube, and completely avoid the problem of coating shedding in the spraying scheme, thereby increasing the stability of the operation of the electric vacuum device.

[0071] In order to verify the effect of the heat dissipation method proposed in this application, multi-physics finite element software is used to simulate the overall temperature inside the X-ray tube under the three treatment schemes. The target plate is made of a composite material of TZM alloy and graphite, and the metal tube shell 210 is made of stainless steel. Figure 8-Figure 10 The simulation software was used to show the temperature distribution results of the anode target disk under two schemes: Fe3O4 coating and 220 curved array of heat dissipation strips. The parameters were set to an average beam power of 3.5kW, continuous heat dissipation mode, and cooling oil temperature of 80℃. Under the Fe3O4 spraying process, the radiation heat transfer coefficient was 0.88, and the maximum target temperature was 946.8℃. Under the surface roughening process, the radiation coefficient was 0.7. Although the radiation coefficient was slightly lower than that of the Fe3O4 spraying process, the temperature dropped to 835.1℃ after combining with the brazing heat dissipation strip 220 curved array. Compared with the spraying process, the temperature dropped by 12%, proving that the brazing heat dissipation strip 220 curved array based on the surface roughening process can effectively improve the heat dissipation inside the X-ray tube. And it avoids the risk of ignition caused by coating shedding.

[0072] The above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. A tube core assembly for improving the heat dissipation performance of an X-ray tube, comprising a cathode assembly, a shell assembly connected to the cathode assembly, and an anode assembly located in the shell assembly and rotating along the axial direction of the shell assembly, characterized in that: The shell assembly includes a tube shell, the inner wall of which is provided with a plurality of heat dissipation bars, and the plurality of heat dissipation bars enclose the anode assembly in the middle of the tube shell; When the cathode assembly emits an electron beam to the anode assembly, heat is dissipated inside the shell assembly through the tube shell and the heat dissipation strip; The heat dissipation strips are welded to the inner wall of the tube shell in an orderly manner along the axial curved surface of the tube shell; The back of the heat dissipation bar close to the inner wall of the tube shell is provided with a welding groove, and solder is arranged in the welding groove, and the heat dissipation bar is welded to the inner wall of the tube shell through the solder.

2. A tube core assembly for improving the heat dissipation performance of an X-ray tube according to claim 1, characterized in that: The cross section of the heat dissipation strip is a perfect semicircle or ellipse structure.

3. A tube core assembly for improving the heat dissipation performance of an X-ray tube according to claim 2, characterized in that: The radiation heat dissipation angle of the heat dissipation strip is 177°.

4. The tube core assembly for improving the heat dissipation performance of an X-ray tube according to claim 1, characterized in that: There are 24 heat dissipation strips.

5. The tube core assembly for improving the heat dissipation performance of an X-ray tube according to claim 4, characterized in that: The included angle between adjacent heat dissipation strips is 15°.

6. A tube shell manufacturing method, using a tube core assembly for improving the heat dissipation performance of an X-ray tube according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1. Select the heat sink length that matches the tube shell height; Step 2: Use a milling cutter to mill out a welding groove in the length direction of the back of the heat sink. The width and height of the welding groove are 1mm*1mm or 0.5mm*0.5mm respectively, and the length of the welding groove is equal to the length of the heat sink. The fitting curved surface of the heat dissipation strip is the same as the inner wall curved surface of the tube shell; Step 3: Place the solder in the soldering tank and fix it with a tool; Step 4: Place the tube shell in a vacuum furnace or hydrogen furnace and heat it to 800-1200°C to melt the solder. Using the capillary effect, the solder is evenly spread in the gap between the heat dissipation strip and the inner wall of the tube shell. Step 5: After cooling, the inner surface of the tube shell is roughened.

7. The tube shell manufacturing method according to claim 6, characterized in that: In step 1, the tube shell and the heat sink are made of oxygen-free copper or dispersed copper material, so that the thermal expansion of the tube shell and the heat sink is the same.

8. The tube shell manufacturing method according to claim 6, characterized in that: In step 5, the roughening is performed by sandblasting or laser irradiation.

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