Preparation method of surface shunting REBCO dipping coil and welding device required by method

Abstract

The invention discloses a preparation method of a surface shunting REBCO dipping coil and a welding device required by the method, and relates to the technical field of REBCO dipping coils. The welding device comprises a C-shaped clamping device and a heating device, the C-shaped clamping device comprises a fastening screw rod, a C-shaped column and a pressing block, and the heating device comprises a heat sink, a heating rod and a temperature controller for controlling the temperature of the heating rod; wherein the fastening screw penetrates through a threaded hole in the upper portion of the C-shaped column and is connected with the pressing block, the heating rods are installed in through holes of the heat sinks, and the two heat sinks are located on the two sides of the uninsulated superconducting coil respectively. Metal sheets are welded on the upper surface and the lower surface of the non-insulation superconducting coil through the C-shaped clamping device and the heating device, and a shunting channel is added, so that the non-insulation superconducting coil still has shunting capacity after being impregnated, quench protection safety performance of the impregnated coil and a magnet is improved, and the service life of the coil is prolonged. And the mechanical structure of the REBCO coil before epoxy impregnation is improved, and the mechanical stability of the coil is enhanced.

Description

Technical Field

[0001] This invention relates to the field of REBCO impregnated coil technology, and more specifically to a method for preparing a surface-splitting REBCO impregnated coil and the welding apparatus required for this method. Background Technology

[0002] Superconducting magnets are small in size, save significant energy during operation, and generate high-intensity magnetic fields, making them highly practical and widely used in industrial production, medicine, and scientific research. Epoxy resin, as an insulating material, is used to encapsulate superconducting magnets, restricting the movement of the superconducting coil under electromagnetic forces and providing mechanical strength and thermal conductivity, which are crucial for the stable operation of the superconducting magnet. However, both cryogenic and high-temperature superconducting magnets face some practical problems after encapsulation. Epoxy resin has low strength and poor toughness, making it prone to cracking; its adhesion is poor, leading to debonding; and its thermal conductivity is extremely low at low temperatures. For high-temperature superconducting magnets such as REBCO (YBCO), the main problem is that the multi-layered structure of REBCO tapes makes them susceptible to epoxy resin-induced performance degradation. Epoxy resin entering between turns increases the insulation performance of the high-temperature superconducting coil, easily causing irreversible quenching. Therefore, there is an urgent need for a method that can improve the mechanical strength of high-temperature superconducting coils after impregnation while also providing radial current shunting and quenching protection. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a surface-splitting REBCO impregnated coil and the welding apparatus required for this method, so as to solve the problems existing in the prior art.

[0004] This invention provides a technical solution: A method for preparing a surface-splitting REBCO-impregnated coil includes the following steps: Step 1: Plan the radial surface shunt positions on the surface of the wound uninsulated superconducting coil, and plan multiple positions on the same surface or the entire upper surface as shunt paths; Step 2: Add solder to the planned flow path and distribute the added solder evenly on the flow path; Step 3: Start the heating device to uniformly melt the solder arranged on the surface of the uninsulated superconducting coil, control the welding temperature at 180-210℃, and the heating time is less than 30s. The gaps between turns in the shunt path area are filled with molten solder. Step 4: Cut a thin metal sheet that matches the area and shape of the planned diversion path; Step 5: Evenly distribute the same type of solder on the metal sheet, and use the heating method in Step 3 to make the solder melt and distribute evenly on the surface of the metal sheet, or directly heat the metal sheet to melt it. Step 6: Align the side of the metal sheet with the solder plating with the side of the non-insulated superconducting coil with the solder plating, or directly align the metal sheet with the side of the non-insulated superconducting coil with the solder plating, and then place the heat sink on the metal sheet and fix it with a C-clamping device. Step 7: Connect the heating rod to the temperature controller and place it on the through hole of the heat sink. Control the heating temperature at 180-210℃. When the solder on the surface of the non-insulated superconducting coil begins to melt, apply pressure through the fastening screw to weld the solder, the non-insulated superconducting coil, and the metal sheet together tightly. The heating time is less than 2 minutes. After cooling the non-insulated superconducting coil with anhydrous ethanol, disassemble the C-type clamping device and the heating device. Step 8: Repeat steps 2 to 7 to weld the remaining shunt channels, complete the welding of the shunt path area, and then perform vacuum epoxy pressure impregnation to complete the preparation of the REBCO impregnated coil with surface shunt.

[0005] Furthermore, the non-insulated superconducting coil mentioned in step 1 is a double-pancake superconducting coil wound with non-insulated superconducting tape or a double-pancake superconducting coil wound with non-insulated superconducting tape and stainless steel tape.

[0006] Furthermore, the shunt paths are located on the upper and lower surfaces of the double-pancake superconducting coils, and the shunt path positions on the upper and lower surfaces are symmetrically distributed. The double-pancake superconducting coils are separated by insulation using G10 patches.

[0007] Furthermore, the inner diameter of the shunt path is consistent with the inner diameter of the coil frame, and the outer diameter of the shunt path is consistent with the outer diameter of the uninsulated superconducting coil.

[0008] Furthermore, the solder used in step 2 is a paste solder, indium tin solder, or tin-lead solder, and the soldering temperature is less than 200°C.

[0009] Furthermore, the metal sheet mentioned in step 5 is made of copper, indium, or aluminum.

[0010] Furthermore, when using indium foil, no additional solder is required; it can be directly applied to the surface of the uninsulated superconducting coil and then heated and melted using a heating device.

[0011] Furthermore, the thickness of the metal sheet is 0.2mm-0.5mm, and after covering, it is flush with the upper surface of the coil frame. The heating temperature is 150℃-185℃, and the heating time is less than 2 minutes.

[0012] A welding apparatus required for a method of preparing a surface-splitting REBCO impregnated coil includes a C-clamping device and a heating device. The C-clamping device includes a fastening screw, a C-shaped post, and a pressure block. The heating device includes a heat sink, a heating rod, and a temperature controller for controlling the temperature of the heating rod. The fastening screw passes through the threaded hole at the top of the C-shaped column and is connected to the pressure block. The heating rod is installed in the through hole of the heat sink. The two heat sinks are located on both sides of the uninsulated superconducting coil.

[0013] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention improves the mechanical structure of REBCO coil before epoxy impregnation and enhances the mechanical stability of the coil by filling the inter-turns with molten metal solder and welding metal sheets on the surface of the non-insulated superconducting coil to form a shunt region on the coil surface. 2. The welding area of ​​the metal sheet of this invention is small, which facilitates disassembly for welding the external connector of the non-insulated superconducting coil and adjusting its position. Then, the entire magnet is subjected to epoxy vacuum pressure impregnation. In addition, during the low-temperature test and cooling process, the metal sheet not only increases the mechanical strength to resist the deformation caused by the temperature difference, but also forms radial cooling channels on the coil, which homogenizes the temperature distribution during the cooling process. 3. By adding a radial shunt path to the surface of the non-insulated superconducting coil, this invention can increase the stability of the magnet, reduce the inter-turn resistivity, enhance the inter-turn shunt capability, and maintain good shunt capability even after epoxy impregnation, thereby improving the quench protection safety performance of the impregnated coil and magnet. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the welding apparatus of the present invention.

[0015] Figure 2 This is a schematic diagram of the metal sheet of the present invention.

[0016] Figure 3 This is a schematic diagram of the diversion path area of ​​the present invention.

[0017] Explanation of reference numerals in the attached diagram: 1-Fastening bolt, 2-C-shaped column, 3-Pan block, 4-Heat sink, 5-Heating rod, 6-Metal sheet, 7-Uninsulated superconducting coil, 8-Coil frame. Detailed Implementation

[0018] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] This invention provides a method for preparing a surface-splitting REBCO-impregnated coil, comprising the following steps: Step 1: Plan the radial surface shunt positions on the surface of the wound uninsulated superconducting coil 7, and plan multiple positions on the same surface or the entire upper surface as shunt paths; Step 2: Add solder to the planned flow path and distribute the added solder evenly on the flow path; Step 3: Start the heating device to uniformly melt the solder arranged on the surface of the uninsulated superconducting coil 7, control the welding temperature at 180-210℃, and the heating time is less than 30s. The gap between turns in the shunt path area is filled with the molten solder. Step 4: Cut a thin metal sheet 6 that matches the area and shape of the planned diversion path; Step 5: Evenly distribute the same solder on the metal sheet 6, and use the heating method in step 3 to make the solder melt and distribute evenly on the surface of the metal sheet 6, or directly heat the metal sheet 6 to melt it. Step 6: Align the side of the metal sheet 6 with the side of the non-insulated superconducting coil 7 with the side of the non-insulated superconducting coil 7 with the side of the non-insulated superconducting coil 7 with the solder, or directly align the metal sheet 6 with the side of the non-insulated superconducting coil 7 with the solder, and then place the heat sink 4 on the metal sheet 6 and fix it with a C-type clamping device. Step 7: Connect the heating rod 5 to the temperature controller and place it on the through hole of the heat sink 4. Control the heating temperature at 180-210℃. When the solder on the surface of the non-insulated superconducting coil 7 begins to melt, apply pressure through the fastening screw 1 to weld the solder, the non-insulated superconducting coil 7, and the metal sheet 6 together tightly. The heating time is less than 2 minutes. After cooling the non-insulated superconducting coil 7 with anhydrous ethanol, disassemble the C-type clamping device and the heating device. Step 8: Repeat steps 2 to 7 to weld the remaining shunt channels, complete the welding of the shunt path area, and then perform vacuum epoxy pressure impregnation to complete the preparation of the REBCO impregnated coil with surface shunt.

[0020] Preferably, in step 1, the uninsulated superconducting coil 7 is a double-panel superconducting coil wound with uninsulated superconducting tape or a double-panel superconducting coil wound with both uninsulated superconducting tape and stainless steel tape. The shunt paths are located on the upper and lower surfaces of the double-panel superconducting coil, and the shunt path positions on the upper and lower surfaces are symmetrically distributed. The double-panel superconducting coils are separated by G10 patches for insulation. The inner diameter of the shunt path is the same as the inner diameter of the coil frame 8, and the outer diameter of the shunt path is the same as the outer diameter of the uninsulated superconducting coil 7.

[0021] Preferably, in step 2, the solder used is paste solder, indium tin solder, or tin-lead solder, and the soldering temperature is less than 200°C.

[0022] Preferably, the metal sheet 6 in step 5 is made of copper, indium, or aluminum. When indium is used, no additional solder is needed; it is directly applied to the surface of the uninsulated superconducting coil 7 and then melted using a heating device. The thickness of the metal sheet 6 is 0.2mm-0.5mm, and after application, it is flush with the upper surface of the coil frame 8. The heating temperature is 150℃-185℃, and the heating time is less than 2 minutes.

[0023] Please see Figures 1 to 3 The welding apparatus required for the above preparation method includes a C-type clamping device and a heating device. The C-type clamping device includes a fastening screw 1, a C-type column 2 and a pressure block 3. The heating device includes a heat sink 4, a heating rod 5 and a temperature controller for controlling the temperature of the heating rod. The fastening screw 1 passes through the threaded hole at the top of the C-type column 2 and is connected to the pressure block 3. The heating rod 5 is installed in the through hole of the heat sink 4. The two heat sinks 4 are located on both sides of the uninsulated superconducting coil 7.

[0024] The technical problem this invention aims to solve is the inability to achieve inter-turn shunt in REBCO-impregnated coils coated with epoxy resin under vacuum pressure. This invention employs a method of welding thin metal sheets onto a pre-wound, uninsulated REBCO superconducting coil to increase the radial current path of the superconducting coil, followed by epoxy resin vacuum pressure impregnation for curing. The resulting coil is a REBCO epoxy resin-cured coil with epoxy resin as the primary impregnation method and radial current paths on its surface. This invention offers advantages in actual magnet assembly. During magnet assembly, the high-temperature superconducting coil can be assembled after welding the metal foil. Because the welding area of ​​the thin metal sheet is small, it facilitates disassembly for welding the external connectors of the high-temperature superconducting coil and adjusting their positions, before the entire magnet is subjected to epoxy vacuum pressure impregnation.

[0025] Example 1

[0026] This embodiment provides a method for fabricating a surface-splitting REBCO impregnated coil, wherein the required welding apparatus, such as... Figure 1 As shown, it includes a C-type clamping device, a heating device, solder, a metal sheet, and a non-insulated superconducting coil; the solder used is solder with a welding temperature of 145°C; the metal sheet is a 0.2mm thick copper sheet flush with the upper surface of the frame; the non-insulated superconducting coil is a double-pancake superconducting coil wound with non-insulated superconducting tape, specifically including the following steps: Step 1: Plan the radial surface shunt positions on the surface of the wound double-pancake non-insulated superconducting coil. Four shunt paths can be evenly planned on the same surface. The inner diameter of the shunt path is consistent with the inner diameter of the skeleton, and the outer diameter is consistent with the outer diameter of the coil. The width is 7mm. The upper and lower shunt positions of the double-pancake coil are symmetrically distributed. Step 2: Add solder to the planned shunt path and spread it evenly on the surface of the coil; Step 3: Using the heat sink, heating rod and temperature controller of the heating device, the solder placed on the surface of the coil is melted evenly. The temperature controller controls the welding temperature at 185°C and the heating time is 30 seconds. The gaps between the turns in the shunt area are filled with molten solder. Step 4: Cut a thin metal sheet that matches the area and shape of the planned diversion path; Step 5: Distribute the same type of solder evenly on the metal sheet, using the same method to ensure that the solder melts and distributes evenly on the surface of the metal sheet; Step 6: Align the side of the metal sheet that has been plated with solder with the side of the coil that has been plated with solder, and then place the heat sink on the metal sheet and use a C-clamp device to fix it. Step 7: Connect the heating rod to the temperature controller and place it on the through hole of the heat sink. Control the heating temperature at 185℃. When the solder on the surface of the coil begins to melt, apply pressure through the fastening screw to make the solder-superconducting coil-metal sheet weld together more tightly. The heating time is 2 minutes. After cooling the coil with anhydrous ethanol, disassemble the C-type clamping device and the heating device. Step 8: The same method can be used to weld the other three shunt path channels to complete the welding of the shunt area. Then, vacuum epoxy pressure impregnation can be performed to complete the preparation of the REBCO impregnated coil with surface shunt.

[0027] Example 2

[0028] This embodiment provides a method for preparing a surface-splitting REBCO-impregnated coil, wherein the required welding apparatus is as follows: Figure 1 As shown, it includes a C-type clamping device, a heating device, solder, a metal sheet, and a non-insulated superconducting coil. The metal sheet used is a 0.2mm thick indium sheet, flush with the upper surface of the frame. Since indium is a soft metal with a low melting point and low resistivity, it has direct welding properties and can be directly welded without additional solder. It is covered on the coil surface and heated and melted by the heating device. The non-insulated superconducting coil is a double-pancake superconducting coil made of non-insulated superconducting strip and stainless steel strip wound together, specifically including the following steps: Step 1: Plan the radial surface shunt positions on the surface of the wound double-pancake uninsulated superconducting coil. Two symmetrical shunt paths can be planned on the same surface. The inner diameter of the shunt path is consistent with the inner diameter of the skeleton, and the outer diameter is consistent with the outer diameter of the coil. The width is 10mm. The upper and lower shunt positions of the double-pancake coil are symmetrically distributed. Step 2: Add indium sheets along the planned shunt path, arranging them evenly on the coil surface; Step 3: Using the heat sink, heating rod, and temperature controller of the heating device, the solder arranged on the surface of the coil is melted evenly. When the indium sheet on the surface of the coil begins to melt, pressure is applied by tightening the screws to make the indium sheet, superconducting coil, and metal sheet weld together more tightly. The temperature controller controls the welding temperature at 180°C and the heating time is 2 minutes. The gaps between turns in the shunt area are filled with molten indium. After cooling the coil with anhydrous ethanol, the C-type clamping device and heating device are disassembled. Step 4: The same method can be used to weld another shunt path channel to complete the welding of the shunt area. Then, vacuum epoxy pressure impregnation can be performed to complete the preparation of the REBCO impregnated coil with surface shunt.

[0029] This invention improves the mechanical structure of the REBCO coil before epoxy impregnation and enhances its mechanical stability by filling the inter-turn spaces with molten metal solder and welding metal sheets onto the coil surface, thus forming a shunt region on the surface of the high-temperature superconducting coil. Furthermore, during the low-temperature cooling process, the metal sheets not only increase mechanical strength to resist deformation caused by temperature differences but also form radial cooling channels on the superconducting coil, homogenizing the temperature distribution during cooling. By adding radial shunt paths to the surface of the high-temperature superconducting non-insulated coil, the stability of the magnet is increased, the inter-turn resistivity is reduced, and the inter-turn shunt capability is enhanced. Even after epoxy impregnation, it maintains good shunt capability, improving the quench protection safety performance of the impregnated coil and magnet.

[0030] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method of making a surface-diverted REBCO dipole coil, characterized by, The method comprises the following steps: Step 1: planning the position of the radial surface shunt on the surface of the completed uninsulated superconducting coil (7), planning multiple positions or the entire upper surface as the shunt path on the same surface; Step 2: adding solder on the planned shunt path, and uniformly arranging the added solder on the shunt path; Step 3: starting the heating device, uniformly melting the solder arranged on the surface of the uninsulated superconducting coil (7), controlling the soldering temperature to be 180-210℃, and the heating time to be less than 30s, and the inter-turn gap in the shunt path area is filled with the melted solder; Step 4: cutting a metal sheet (6) consistent with the shape of the planned shunt path area; Step 5: uniformly arranging the same solder on the metal sheet (6), and uniformly melting the solder on the surface of the metal sheet (6) by using the heating method in step 3 or directly melting the metal sheet (6) by heating it; Step 6: aligning the side of the metal sheet (6) coated with solder with the side of the uninsulated superconducting coil (7) coated with solder, or directly aligning the metal sheet (6) with the side of the uninsulated superconducting coil (7) coated with solder, then placing the heat sink (4) on the metal sheet (6) and fixing it using a C-shaped clamping device; Step 7: connecting the heating rod (5) to the temperature controller, placing it on the through hole of the heat sink (4), controlling the heating temperature to be 180-210℃, and when the solder on the surface of the uninsulated superconducting coil (7) starts to melt, applying pressure through the tightening screw (1) to tightly weld the solder, the uninsulated superconducting coil (7) and the metal sheet (6) together, and the heating time is less than 2min, then cooling the uninsulated superconducting coil (7) using anhydrous ethanol, and disassembling the C-shaped clamping device and the heating device; Step 8: repeating steps 2 to 7 to weld the remaining shunt channels, completing the welding of the shunt path area, and then performing vacuum epoxy pressure impregnation to complete the preparation of the surface shunt REBCO impregnated coil.

2. A method of making a surface-diverted REBCO dipole coil as claimed in claim 1, wherein, The uninsulated superconducting coil (7) in step 1 is a double-pie superconducting coil wound by an uninsulated superconducting tape or a double-pie superconducting coil wound by an uninsulated superconducting tape and a stainless steel tape.

3. A method of making a surface-diverted REBCO dipole coil as claimed in claim 2, wherein, The shunt path is located on the upper surface and the lower surface of the double-pie superconducting coil, and the positions of the shunt paths on the upper surface and the lower surface are symmetrically distributed, and the double-pie superconducting coils are insulated and separated by G10 patches.

4. A method of making a surface-diverted REBCO dipole coil as claimed in claim 1, wherein, The inner diameter of the shunt path is consistent with the inner diameter of the coil skeleton (8), and the outer diameter of the shunt path is consistent with the outer diameter of the uninsulated superconducting coil (7).

5. A method of making a surface-diverted REBCO dipole coil as claimed in claim 1, wherein, The solder in step 2 adopts paste solder, indium-tin solder or tin-lead solder, and the soldering temperature of the solder is less than 200℃.

6. A method of making a surface-diverted REBCO dipole coil as claimed in claim 1, wherein, The metal sheet (6) in step 5 adopts a copper sheet, an indium sheet or an aluminum sheet.

7. A method of making a surface-diverted REBCO dipole coil as claimed in claim 6, wherein, When an indium sheet is used, no additional solder is needed, and it is directly covered on the surface of the uninsulated superconducting coil (7), and then heated and melted using a heating device.

8. A method of making a surface-diverted REBCO dipole coil as claimed in claim 6, wherein, The thickness of the metal sheet (6) is 0.2mm-0.5mm, which is flush with the upper surface of the coil skeleton (8) after covering, the heating temperature is 150℃-185℃, and the heating time is less than 2min.

9. A soldering device required for a manufacturing method of a surface-diverted REBCO impregnated coil, characterized by, The C-shaped clamping device comprises a fastening screw (1), a C-shaped column (2) and a pressing block (3), and the heating device comprises a heat sink (4), a heating rod (5) and a temperature controller for controlling the temperature of the heating rod. The fastening screw (1) passes through the threaded hole in the upper part of the C-shaped column (2) and is connected with the pressing block (3), the heating rod (5) is installed in the through hole of the heat sink (4), and the two heat sinks (4) are located on the two sides of the non-insulated superconducting coil (7).

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