High-temperature superconducting joint welding device and welding method thereof

Abstract

The invention provides a high-temperature superconducting connector welding device and a welding method thereof. The device comprises a current source, a through-flow cable, a metal belt, a welding base, a fixing support and a pressure unit. The current source is used for providing current for the metal strip, so that the metal strip generates joule heat; the two ends of the metal band are electrically connected with the current source through the through-flow cable, the metal band covers the connector of the superconducting tape needing to be welded, and welding of the connector of the superconducting tape is achieved through heat of the metal band; the welding base is used for fixing the superconducting coil needing to be welded; the fixing support is used for connecting the metal belt and the pressure unit. The pressure unit is used for providing stress to the two ends of the metal strip so that the metal strip can be tightly attached to the superconducting strip connector, and meanwhile the superconducting strip connector is tightly attached to the surface of the superconducting coil. The technical problems that in the prior art, a superconducting connector welding process is poor in consistency and prone to being affected by a welding space, and a gap exists between a superconducting connector and a superconducting coil can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting coil welding, and in particular to a high-temperature superconducting joint welding device and a welding method thereof. Background Art

[0002] With the development of high-speed magnetic levitation and electromagnetic propulsion technology, high-temperature superconducting magnets are gradually being used in the field of strong magnetic fields due to their advantages of large magnetic field, small size, light weight and high working temperature range (20K-30K). Large-scale high-temperature superconducting magnets generally require up to 104m of wire. The length of a single high-temperature superconducting tape that has been commercially produced is affected by the production process and is generally 200m to 400m. The longer the length of a single tape, the lower the yield and quality control, and the higher the cost. Due to the limitation of the length of the tape, the structure of the high-temperature superconducting magnet is determined to be multiple coils in series, and the coils are connected by superconducting joints. The amount of tape used for large coils also reaches the km level, so there are also multiple superconducting joints inside a single coil.

[0003] High-temperature superconducting joints are generally welded by soldering, which has joint resistance at low temperatures. Superconducting joints have many adverse effects on the stable operation of superconducting magnets. First, since superconducting magnets work in extremely low temperature zones, the refrigeration cost is extremely high, and the heat leakage of the magnet needs to be minimized. The joint resistance will inevitably produce Joule heat loss during the current flow of the superconducting magnet, causing the magnet temperature to rise. Local temperature rise may cause the superconducting magnet to quench and destroy the magnet structure; secondly, the superconducting joint resistance is the main component of the DC resistance in the magnet. For superconducting magnets that need to operate in a closed loop for a long time, their magnetic field must maintain a low attenuation rate, and the DC resistance in the magnet needs to be reduced. Therefore, the quality of joint welding directly affects whether the superconducting magnet can operate stably in a closed loop for a long time.

[0004] The quality of high-temperature superconducting tape joint welding is mainly affected by welding temperature, welding pressure, welding time, joint length, joint shape, solder thickness and other aspects. The current high-temperature superconducting joint welding temperature is generally controlled at 200℃~300℃. The solder on the surface of the superconducting tape is melted by a welding gun, electric soldering iron or other heating device, and a certain pressure is applied to reduce the solder thickness. Then the heating is stopped and the joint structure is stabilized after the temperature returns to normal temperature. In addition, there are special requirements for the shape and length of the joint. For example, the joint between the superconducting coils needs to have a certain arc degree, and the joint length needs to reach tens of cm to reduce the joint resistance. Special welding tooling is required to ensure that the joint does not deform during the welding process.

[0005] Existing superconducting joint welding devices can be divided into two types: manual welding and fixture welding:

[0006] (1) Manual welding is to directly apply welding pressure and control heating time by holding a welding gun. This method is greatly affected by human skills and experience, and it is difficult to ensure the consistency of welding process. In addition, the difficulty of operation is affected by the welding space, and it is difficult to weld joints in a narrow space;

[0007] (2) The clamp welding method generally involves designing a clamp of a specific shape, applying pressure to the strip by bolting, heating the clamp with a welding gun or other heating device, and tightening the bolts during the heating process to squeeze the solder between the strips to make them thinner. After completion, the heating device is removed and the clamp is removed after it has recovered in temperature. The clamp can be arc-shaped or straight-line and is used for joint welding between coils. The disadvantage of this method is that the clamp has a large thermal capacity and a long heating and cooling time, which may cause the superconducting strip to be stratified due to heat. In addition, tightening the clamp with bolts may cause uneven force on the superconducting strip, causing deformation and breakage of the strip. After welding is completed, the clamp needs to be removed, resulting in a gap between the superconducting joint and the superconducting coil, which is not conducive to joint fixation. Summary of the invention

[0008] The present invention provides a high-temperature superconducting joint welding device and a welding method thereof, which can solve the technical problems in the prior art that the superconducting joint welding process has poor consistency, is easily affected by the welding space, and has a gap between the superconducting joint and the superconducting coil.

[0009] According to one aspect of the present invention, there is provided a high temperature superconducting joint welding device, the device comprising a current source, a current-carrying cable, a metal belt, a welding base, a fixing bracket and a pressure unit;

[0010] The current source is used to provide current to the metal strip, so that the metal strip generates Joule heat;

[0011] The two ends of the metal strip are electrically connected to the current source through the current-carrying cable, and the metal strip covers the joints of the superconducting tapes to be welded, and the welding of the joints of the superconducting tapes is achieved by the metal strip's own heat;

[0012] The welding base is used to fix the superconducting coil to be welded;

[0013] The fixing bracket is used to connect the metal belt and the pressure unit;

[0014] The pressure unit is used to provide stress to both ends of the metal tape so that the metal tape is closely attached to the superconducting tape joint, and the superconducting tape joint is closely attached to the surface of the superconducting coil.

[0015] Preferably, the width of the metal tape is greater than the width of a superconducting tape joint to be welded.

[0016] Preferably, the fixed bracket includes a first side plate, a second side plate and a crossbeam, one end of the crossbeam is provided with at least one first connecting hole, and the other end is provided with at least one second connecting hole; one end of the first side plate is provided with a current terminal connected to one end of the metal strip, and the other end is connected to the crossbeam through any of the first connecting holes; one end of the second side plate is provided with a current terminal connected to the other end of the metal strip, and the other end is connected to the crossbeam through any of the second connecting holes; the current-carrying cable is used to connect the current source and the two current terminals of the fixed bracket, so that the current source and the metal strip form a closed loop.

[0017] Preferably, the spacing between the first connection hole connected to the first side plate and the second connection hole connected to the second side plate is determined according to the diameter of the superconducting coil to be welded.

[0018] Preferably, the device further comprises a connecting structure, and the connecting structure is used to connect the crossbeam and the pressure unit.

[0019] Preferably, the pressure unit can be replaced by a weight.

[0020] Preferably, the metal belt is made of a material with high strength, high resistivity and high thermal conductivity.

[0021] According to another aspect of the present invention, a welding method of a high-temperature superconducting joint welding device is provided, wherein the welding method uses any of the above-mentioned welding devices for welding, and the method comprises:

[0022] Fixing two superconducting coils to be welded on a welding base, and overlapping the superconducting tape joints of the two superconducting coils to be welded, with solder placed between the overlapping joints;

[0023] The metal strip is covered on the overlapped superconducting tape joint, the two ends of the metal strip are electrically connected to the current source through the current-carrying cable, and the metal strip is mechanically connected to the pressure unit through the fixing bracket, and the metal strip is tightly attached to the superconducting tape joint under the stress of the pressure unit, and the superconducting tape joint is tightly attached to the surface of the superconducting coil;

[0024] The current source is energized according to the preset heating power, causing the metal strip to generate Joule heat. The metal strip transfers its own heat to the solder between the superconducting tape joints, and at the same time, the solder is squeezed under the action of stress to complete the welding of the superconducting tape joints.

[0025] Preferably, the preset heating power of the current source is determined by the following method:

[0026] Determine the welding target temperature based on the material of the superconducting coil to be welded;

[0027] Determine the length and cross-sectional area of ​​the metal tape based on the shape of the superconducting coil to be welded;

[0028] Obtaining the resistance of the metal strip based on the length and cross-sectional area of ​​the metal strip;

[0029] The heating power of the metal strip is obtained based on the resistance of the metal strip and the current value flowing through the metal strip;

[0030] obtaining the thermal contact resistance between the metal tape and the superconducting coil based on the length and cross-sectional area of ​​the superconducting tape joint;

[0031] obtaining the heating power delivered by the metal tape to the superconducting coil based on the thermal contact resistance between the metal tape and the superconducting coil, the current temperature of the metal tape and the current temperature of the superconducting tape joint;

[0032] Based on the heating power of the metal strip, the heating power transferred from the metal strip to the superconducting coil, the actual temperature of the metal strip, the actual temperature of the superconducting tape joint, and the initial temperature of the superconducting tape joint and the metal strip, the change curves of the actual temperatures of the metal strip and the superconducting tape joint with the preset heating power and the current flow time are obtained, and the corresponding heating power that meets the welding target temperature and the current flow time is found on the change curve, and the corresponding heating power is used as the preset heating power of the current source.

[0033] Preferably, the resistance of the metal strip is obtained by the following formula:

[0034]

[0035] The heating power of the metal strip is obtained by the following formula:

[0036] P 1 =I 2 ·R 1 ;

[0037] The thermal contact resistance between the metal tape and the superconducting coil is obtained by the following formula:

[0038]

[0039] The heating power transferred from the metal tape to the superconducting coil is obtained by the following formula:

[0040]

[0041] The actual temperature curve of the joint between the metal tape and the superconducting tape as a function of the heating power and the current flow time is obtained by the following formula:

[0042] (P 1 -P 2 )·t=C 1 m 1 ·(T 1 -T 0 );

[0043] P 2 t=C 2 m 2 ·(T 2 -T 0 );

[0044] In the formula, R 1 is the resistance of the metal strip, ρ is the resistivity of the metal strip, L 1 is the length of the metal strip, S 1 is the cross-sectional area of ​​the metal strip, P 1 is the heating power of the metal strip, I is the current flowing, R C is the thermal contact resistance between the metal tape and the superconducting coil, L 2 is the length of the superconducting tape joint, k is the thermal conductivity of the metal tape, S 2 is the cross-sectional area of ​​the superconducting tape joint, P 2 is the heating power transferred from the metal tape to the superconducting coil, T 0 , T 1 , T 2 are the initial temperature of the superconducting tape joint and the metal tape, the current temperature of the metal tape, and the current temperature of the superconducting tape joint, respectively; t is the flow time, C 1 and m 1 are the specific heat capacity and mass of the metal strip, C 2 and m 2 are the specific heat capacity and mass of the superconducting tape joint, respectively.

[0045] By applying the technical solution of the present invention, the superconducting tape joint is compressed by replacing the clamp with a metal belt, Joule heat is generated when the metal belt flows, and pressure is applied to the metal belt. Since the metal belt is a flexible structure compared with the traditional clamp, it can be in close contact with the superconducting tape joint to ensure the uniformity of the force of the welded tape joint; after the welding is completed, it is only necessary to stop the flow, and the temperature of the metal belt will drop rapidly, which is beneficial to the thermal stability of the superconducting tape joint and prevent the superconducting tape from thermal stratification; in addition, according to specific needs, the metal belt can be used in the welding of joints with different tape types, different coil shapes, and different welding lengths, and the joint can be made close to the surface of the superconducting tape to avoid the situation where there is a gap between the joint and the coil, reduce the risk of joint damage, and facilitate the fixation of the joint. The present invention improves the thermal control performance, the structural stability of the superconducting joint, and has better adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 A schematic structural diagram of a high-temperature superconducting joint welding device provided according to an embodiment of the present invention is shown.

[0048] The above drawings include the following reference numerals:

[0049] 1. Current source; 2. Current cable; 3. Metal belt; 4. Welding base; 5. Fixed bracket; 6. Pressure unit; 7. Superconducting coil. DETAILED DESCRIPTION

[0050] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0052] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0053] like Figure 1 As shown, the present invention provides a high-temperature superconducting joint welding device, the device comprising a current source 1, a current-carrying cable 2, a metal belt 3, a welding base 4, a fixing bracket 5 and a pressure unit 6;

[0054] The current source 1 is used to provide current to the metal strip 3, so that the metal strip 3 generates Joule heat; wherein the temperature change of the metal strip 3 is controlled by adjusting the value of the flowing current;

[0055] The two ends of the metal strip 3 are electrically connected to the current source 1 through the current-carrying cable 2. The metal strip 3 covers the joints of the superconducting tapes to be welded, and the welding of the joints of the superconducting tapes is achieved by its own heat.

[0056] The welding base 4 is used to fix the superconducting coil 7 to be welded;

[0057] The fixing bracket 5 is used to connect the metal belt 3 and the pressure unit 6;

[0058] The pressure unit 6 is used to provide stress to both ends of the metal strip 3 so that the metal strip 3 is closely attached to the superconducting tape joint, and the superconducting tape joint is closely attached to the surface of the superconducting coil 7 .

[0059] The present invention uses a metal belt 3 to replace a clamp to compress the superconducting tape joint, generates Joule heat when the metal belt 3 flows, and applies pressure to the metal belt 3. Since the metal belt 3 is a flexible structure compared to the traditional clamp, it can be in close contact with the superconducting tape joint to ensure the uniformity of the force of the welded tape joint; after the welding is completed, it is only necessary to stop the flow, and the temperature of the metal belt 3 will drop rapidly, which is beneficial to the thermal stability of the superconducting tape joint and prevent the superconducting tape from thermal stratification; in addition, according to specific needs, the metal belt 3 can be applied to the joint welding of different tape types, different coil shapes, and different welding lengths, and the joint can be made close to the surface of the superconducting tape to avoid the situation where there is a gap between the joint and the coil, reduce the risk of joint damage, and facilitate the fixation of the joint. The present invention improves the thermal control performance, the structural stability of the superconducting joint, and has better adaptability.

[0060] According to one embodiment of the present invention, in order to improve the compression effect of the metal tape 3 on the superconducting tape joint, the width of the metal tape 3 is greater than the width of the superconducting tape joint to be welded, and the length of the metal tape 3 can be adapted according to the required welding length.

[0061] Furthermore, the metal belt 3 is made of a material with high strength, high resistivity and high thermal conductivity. The metal belt 3 has a low thickness and a low heat capacity.

[0062] According to one embodiment of the present invention, the fixed bracket 5 includes a first side plate, a second side plate and a crossbeam, one end of the crossbeam is provided with at least one first connecting hole, and the other end is provided with at least one second connecting hole; one end of the first side plate is provided with a current terminal connected to one end of the metal belt 3, and the other end is connected to the crossbeam through any of the first connecting holes; one end of the second side plate is provided with a current terminal connected to the other end of the metal belt 3, and the other end is connected to the crossbeam through any of the second connecting holes; the current cable 2 is used to connect the two current terminals of the current source 1 and the fixed bracket 5, so that the current source 1 and the metal belt 3 form a closed loop.

[0063] Specifically, the spacing between the first connection hole connected to the first side plate and the second connection hole connected to the second side plate is determined according to the diameter of the superconducting tape to be welded.

[0064] According to an embodiment of the present invention, the device further comprises a connecting structure, and the connecting structure is used to connect the crossbeam and the pressure unit 6 .

[0065] According to an embodiment of the present invention, the pressure unit 6 can be replaced by a weight.

[0066] According to an embodiment of the present invention, the metal strip 3 is connected to the current terminal via bolts.

[0067] The present invention also provides a welding method of a high-temperature superconducting joint welding device, wherein the welding method uses any of the above-mentioned welding devices for welding, and the method comprises:

[0068] Fix the two superconducting coils 7 to be welded on the welding base 4, and overlap the superconducting tape joints of the two superconducting coils 7 to be welded, and place solder between the overlapped joints;

[0069] The metal strip 3 is covered on the overlapped superconducting tape joint, and both ends of the metal strip 3 are electrically connected to the current source 1 through the current cable 2, and are mechanically connected to the pressure unit 6 through the fixing bracket 5. Under the stress of the pressure unit 6, the metal strip 3 is tightly attached to the superconducting tape joint, and the superconducting tape joint is tightly attached to the surface of the superconducting coil 7;

[0070] The current source 1 is energized according to the preset heating power, so that the metal strip 3 generates Joule heat. The metal strip 3 transfers its own heat to the solder between the superconducting tape joints, and at the same time squeezes the solder under the action of stress to complete the welding of the superconducting tape joints.

[0071] According to an embodiment of the present invention, the preset heating power of the current source 1 is determined by the following method:

[0072] Determine the welding target temperature based on the material of the superconducting coil 7 to be welded;

[0073] Determine the length and cross-sectional area of ​​the metal strip 3 based on the shape of the superconducting coil 7 to be welded;

[0074] Obtaining the resistance of the metal strip 3 based on the length and cross-sectional area of ​​the metal strip 3;

[0075] Obtaining the heating power of the metal strip 3 based on the resistance and the current value flowing through the metal strip 3;

[0076] Obtaining the thermal contact resistance between the metal tape 3 and the superconducting coil 7 based on the length and cross-sectional area of ​​the superconducting tape joint;

[0077] Obtaining the heating power transmitted from the metal tape 3 to the superconducting coil 7 based on the thermal contact resistance between the metal tape 3 and the superconducting coil 7, the current temperature of the metal tape 3 and the current temperature of the superconducting tape joint;

[0078] Based on the heating power of the metal strip 3, the heating power transmitted from the metal strip 3 to the superconducting coil 7, the actual temperature of the metal strip 3, the actual temperature of the superconducting tape joint, and the initial temperature of the superconducting tape joint and the metal strip 3, the variation curves of the actual temperatures of the metal strip 3 and the superconducting tape joint with the preset heating power and the current flow time are obtained, and the corresponding heating power when the welding target temperature and the current flow time are met is found on the variation curve, and the corresponding heating power is used as the preset heating power of the current source 1, so as to realize the control of the welding temperature by controlling the preset heating power.

[0079] Specifically, the resistance of the metal strip is obtained by the following formula:

[0080]

[0081] The heating power of the metal strip is obtained by the following formula:

[0082] P 1 =I 2 ·R 1 ;

[0083] The thermal contact resistance between the metal tape and the superconducting coil is obtained by the following formula:

[0084]

[0085] The heating power transferred from the metal tape to the superconducting coil is obtained by the following formula:

[0086]

[0087] The actual temperature curve of the joint between the metal tape and the superconducting tape as a function of the heating power and the current flow time is obtained by the following formula:

[0088] (P 1 -P 2 )·t=C 1 m 1 ·(T 1 -T 0 );

[0089] P 2 t=C 2 m 2 ·(T 2 -T 0 );

[0090] In the formula, R 1 is the resistance of the metal strip, ρ is the resistivity of the metal strip, L 1 is the length of the metal strip, S 1 is the cross-sectional area of ​​the metal strip, P 1 is the heating power of the metal strip, I is the current flowing, R Cis the thermal contact resistance between the metal tape and the superconducting coil, L 2 is the length of the superconducting tape joint, k is the thermal conductivity of the metal tape, S 2 is the cross-sectional area of ​​the superconducting tape joint, P 2 is the heating power transferred from the metal tape to the superconducting coil, T 0 , T 1 , T 2 are the initial temperature of the superconducting tape joint and the metal tape, the current temperature of the metal tape, and the current temperature of the superconducting tape joint, respectively; t is the flow time, C 1 and m 1 are the specific heat capacity and mass of the metal strip, C 2 and m 2 are the specific heat capacity and mass of the superconducting tape joint, respectively.

[0091] In summary, the present invention provides a high-temperature superconducting joint welding device and a welding method thereof, wherein a metal belt 3 is used to replace a clamp to compress the superconducting tape joint, Joule heat is generated by the flow of the metal belt 3, and pressure is applied to the metal belt 3. Since the metal belt 3 is a flexible structure compared to the traditional clamp, it can be in close contact with the superconducting tape joint to ensure the uniformity of the force of the welded tape joint; after the welding is completed, it is only necessary to stop the flow, and the temperature of the metal belt 3 will drop rapidly, which is beneficial to the thermal stability of the superconducting tape joint and prevent the superconducting tape from thermal stratification; in addition, according to specific needs, the metal belt 3 can be applied to the welding of joints of different tape types, different coil shapes, and different welding lengths, and the joint can be made close to the surface of the superconducting tape to avoid the situation where there is a gap between the joint and the coil, reduce the risk of joint damage, and facilitate the fixing of the joint. The present invention improves the thermal control performance, the structural stability of the superconducting joint and has better adaptability.

[0092] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0093] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0094] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0095] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high temperature superconducting joint welding device, It is characterized in that The device comprises: the device comprises a current source, a current-carrying cable, a metal belt, a welding base, a fixing bracket and a pressure unit; The current source is used to provide current to the metal strip, so that the metal strip generates Joule heat; The two ends of the metal strip are electrically connected to the current source through the current-carrying cable, and the metal strip covers the joints of the superconducting tapes to be welded, and the welding of the joints of the superconducting tapes is achieved by the metal strip's own heat; The welding base is used to fix the superconducting coil to be welded; The fixing bracket is used to connect the metal belt and the pressure unit; The pressure unit is used to provide stress to both ends of the metal tape so that the metal tape is closely attached to the superconducting tape joint, and the superconducting tape joint is closely attached to the surface of the superconducting coil.

2. The device according to claim 1, It is characterized in that The width of the metal tape is greater than the width of the superconducting tape joint to be welded.

3. The device according to claim 1, It is characterized in that The fixed bracket includes a first side plate, a second side plate and a crossbeam, one end of the crossbeam is provided with at least one first connecting hole, and the other end is provided with at least one second connecting hole; one end of the first side plate is provided with a current terminal connected to one end of the metal belt, and the other end is connected to the crossbeam through any of the first connecting holes; one end of the second side plate is provided with a current terminal connected to the other end of the metal belt, and the other end is connected to the crossbeam through any of the second connecting holes; the current-carrying cable is used to connect the current source and the two current terminals of the fixed bracket, so that the current source and the metal belt form a closed loop.

4. The device according to claim 3, It is characterized in that The distance between the first connection hole connected to the first side plate and the second connection hole connected to the second side plate is determined according to the diameter of the superconducting coil to be welded.

5. The device according to claim 1, It is characterized in that The device further comprises a connecting structure for connecting the crossbeam and the pressure unit.

6. The device according to claim 1, It is characterized in that The pressure unit may be replaced by a weight.

7. The device according to claim 1, It is characterized in that The metal belt is made of a material with high strength, high resistivity and high thermal conductivity.

8. A welding method for a high-temperature superconducting joint welding device, It is characterized in that The welding method is performed by using the welding device described in any one of claims 1 to 7, and the method comprises: Fixing two superconducting coils to be welded on a welding base, and overlapping the superconducting tape joints of the two superconducting coils to be welded, with solder placed between the overlapping joints; The metal strip is covered on the overlapped superconducting tape joint, the two ends of the metal strip are electrically connected to the current source through the current-carrying cable, and the metal strip is mechanically connected to the pressure unit through the fixing bracket, and the metal strip is closely attached to the superconducting tape joint under the stress of the pressure unit, and the superconducting tape joint is closely attached to the surface of the superconducting coil; The current source is energized according to the preset heating power, causing the metal strip to generate Joule heat. The metal strip transfers its own heat to the solder between the superconducting tape joints, and at the same time, the solder is squeezed under the action of stress to complete the welding of the superconducting tape joints.

9. The method according to claim 8, It is characterized in that The preset heating power of the current source is determined by: Determine the welding target temperature based on the material of the superconducting coil to be welded; Determine the length and cross-sectional area of ​​the metal tape based on the shape of the superconducting coil to be welded; Obtaining the resistance of the metal strip based on the length and cross-sectional area of ​​the metal strip; The heating power of the metal strip is obtained based on the resistance of the metal strip and the current value flowing through the metal strip; obtaining the thermal contact resistance between the metal tape and the superconducting coil based on the length and cross-sectional area of ​​the superconducting tape joint; obtaining the heating power delivered by the metal tape to the superconducting coil based on the thermal contact resistance between the metal tape and the superconducting coil, the current temperature of the metal tape and the current temperature of the superconducting tape joint; Based on the heating power of the metal strip, the heating power transferred from the metal strip to the superconducting coil, the actual temperature of the metal strip, the actual temperature of the superconducting tape joint, and the initial temperature of the superconducting tape joint and the metal strip, the change curves of the actual temperatures of the metal strip and the superconducting tape joint with the preset heating power and the current flow time are obtained, and the corresponding heating power that meets the welding target temperature and the current flow time is found on the change curve, and the corresponding heating power is used as the preset heating power of the current source.

10. The method according to claim 8 or 9, It is characterized in that The resistance of the metal strip is obtained by the following formula: The heating power of the metal strip is obtained by the following formula: P 1 =I 2 ·R 1 ; The thermal contact resistance between the metal tape and the superconducting coil is obtained by the following formula: The heating power transferred from the metal tape to the superconducting coil is obtained by the following formula: The actual temperature curve of the joint between the metal tape and the superconducting tape as a function of the heating power and the current flow time is obtained by the following formula: (P 1 -P 2 )·t=C 1 m 1 ·(T 1 -T 0 ); P 2 ·t=C 2 m 2 ·(T 2 -T 0 ); In the formula, R 1 is the resistance of the metal strip, ρ is the resistivity of the metal strip, L 1 is the length of the metal strip, S 1 is the cross-sectional area of ​​the metal strip, P 1 is the heating power of the metal strip, I is the current flowing, R C is the thermal contact resistance between the metal tape and the superconducting coil, L 2 is the length of the superconducting tape joint, k is the thermal conductivity of the metal tape, S 2 is the cross-sectional area of ​​the superconducting tape joint, P 2 is the heating power transferred from the metal tape to the superconducting coil, T 0 , T 1 , T 2 are the initial temperature of the superconducting tape joint and the metal tape, the current temperature of the metal tape, and the current temperature of the superconducting tape joint, respectively; t is the flow time, C 1 and m 1 are the specific heat capacity and mass of the metal strip, C 2 and m 2 are the specific heat capacity and mass of the superconducting tape joint, respectively.

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