Current lead joint structure and welding method thereof

Abstract

The application provides a current lead joint structure and a welding method thereof, and the structure comprises a current lead, a fixing component, a superconducting wire and solder; the first end of the current lead is provided with a groove along the axial direction of the current lead; the fixing component is a U-shaped plate structure matched with the groove, and the fixing component is inverted in the groove to form a tubular structure with open ends; the first section of the superconducting wire is a superconducting bare wire with a wrapping layer removed, and the second section is a superconducting bus with a wrapping layer not removed; the superconducting bare wire is arranged in the tubular structure, and the superconducting bus is arranged outside the tubular structure; the solder is laid in the tubular structure and completely immerses the superconducting bare wire; the superconducting bare wire, the first end of the current lead and the solder are fused into one by heating and cooling the solder, so as to realize the welding of the superconducting wire and the current lead. The application can solve the technical problems of the current lead joint structure in the prior art, such as large welding point contact resistance, local hot spot hidden danger and difficult disassembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current lead, in particular to a current lead joint structure and a welding method thereof. BACKGROUND

[0002] The dewar for liquid helium immersion type coil test contains an inner container and an outer container, and there is a vacuum interlayer between the inner and outer containers. The inner container contains low-temperature liquid, such as liquid nitrogen (-196℃) or liquid helium (-269℃). The superconducting coil in the inner container is generally excited by a power supply at room temperature. The transition section from room temperature to the superconducting coil at liquid helium temperature is called a current lead. In the inner low-temperature container of the test dewar, the lead-out wires of components such as protection circuit, superconducting switch and superconducting coil are connected to the room temperature power supply through the current lead. The lead-out wires of the components are fixed to the end joint structure of the current lead by solder. The heat leakage of the soldered terminal of the current lead largely determines the consumption of liquid helium of the superconducting magnet during excitation test, and there is also a risk of losing superconductivity.

[0003] At present, the current lead joint structure used in the liquid helium immersion type superconducting coil test dewar is formed by welding the lead-out wires of components such as protection circuit, superconducting switch and superconducting coil to the end joint of the current lead. The specific welding method is as follows:

[0004] (1) Before welding, prepare about 200mm of superconducting bare wire for each component lead-out wire;

[0005] (2) Use an electric iron to hang solder on the surface of the superconducting bare wire of each component lead-out wire;

[0006] (3) Use an electric iron to fully hang solder on the end joint structure of the current lead;

[0007] (4) Wrap the soldered superconducting bare wire of each component lead-out wire around the end of the current lead, and then intermittently wrap copper wire around the periphery;

[0008] (5) Use solder to weld the entire wire with copper wire wrapped around it again to reinforce the solder joint.

[0009] However, the current lead joint structure obtained by using the above welding process has the following disadvantages:

[0010] (1) Large solder joint contact resistance, with local hot spot hidden danger

[0011] Although the component lead and the current lead end joint are fully hung with solder before welding, there is still a problem of incomplete contact, which leads to virtual connection and large contact resistance. Meanwhile, the copper wire is part of the welding point during winding and reinforcement, and current passes through it, which generates hot spots on the copper wire and causes the superconducting wire to overheat. This increases the consumption of liquid helium during the excitation test and reduces the stability of the superconducting coil excitation process.

[0012] (2) Difficult to disassemble and assemble

[0013] The copper wire winding and the solder covering make it difficult to disassemble and assemble the device using superconducting wire, and the disassembly of the welding point is complex, which easily damages the wire. SUMMARY

[0014] To solve the above technical problems, the application provides a current lead joint structure and a welding method, which can solve the technical problems of large welding point contact resistance, local hot spot hidden danger and difficult disassembly and assembly in the prior art.

[0015] According to one aspect of the application, a current lead joint structure is provided, which comprises a current lead, a fixing component, a superconducting wire and solder.

[0016] The first end of the current lead is provided with a groove in the axial direction of the current lead;

[0017] The fixing component is a U-shaped plate structure matched with the groove, the fixing component is inverted in the groove to form a tubular structure with open ends, and the length of the fixing component is less than the width of the groove;

[0018] The first section of the superconducting wire is a superconducting bare wire without a wrapping layer, and the second section is a superconducting bus without a wrapping layer, the superconducting bare wire is arranged in the tubular structure, and the superconducting bus is arranged outside the tubular structure, and the length of the superconducting bare wire is less than the length of the fixing component;

[0019] The solder is laid in the tubular structure and completely immerses the superconducting bare wire, the superconducting bare wire, the first end of the current lead and the solder are fused into one by heating and cooling the solder, so as to realize welding of the superconducting wire and the current lead;

[0020] The width direction of the groove is the axial direction of the current lead.

[0021] Preferably, the depth of the groove gradually increases from the first end of the current lead to the second end of the current lead, and the depth direction of the groove is the radial direction of the current lead.

[0022] Preferably, there are multiple grooves, each groove is spaced apart circumferentially along the current lead, and the number of fixing components and the number of superconducting wires are the same as the number of grooves.

[0023] Preferably, the fixing component includes multiple U-shaped plate structures connected end to end.

[0024] Preferably, the structure further includes an insulating layer that wraps around the outside of the second end of the current lead.

[0025] Preferably, the length of the superconducting bare wire is in the range of 175–185 mm.

[0026] Preferably, the current lead is a copper tube.

[0027] Preferably, the wrapping layer is an insulating wrapping layer or a metal wrapping layer.

[0028] According to another aspect of the present invention, a welding method for a current lead connector structure is provided, wherein the method is used to obtain any of the aforementioned current lead connector structures, the method comprising:

[0029] The first segment of the superconducting wire is de-cladding to obtain a bare superconducting wire of a predetermined length;

[0030] The superconducting bare wire is placed in the groove of the current lead, and the fixing component is inverted on the groove to form a tubular structure that wraps the superconducting bare wire.

[0031] Place the first end of the current lead downwards and the second end upwards, and seal the lower port of the tubular structure with a sealing component;

[0032] The solder is poured in from the upper end of the tubular structure until the solder fully submerges the superconducting bare wire;

[0033] The solder inside the tubular structure is heated to melt it until it is completely fused together.

[0034] The molten solder inside the tubular structure is cooled to solidify, the sealing component is removed, and the welding of the superconducting wire and the current lead is completed.

[0035] Compared with the prior art, the application of the technical solution of the present invention has the following beneficial effects:

[0036] (1) Low contact resistance

[0037] During the welding process of the superconducting wires and current leads of each component, a large amount of solder allows their bare superconducting wires to make full contact, avoiding gaps inside each solder joint and eliminating the phenomenon of incomplete soldering. This greatly reduces contact resistance and avoids the problem of excessive Joule heating at the low-temperature end joint of traditional pullable current leads. As a result, the heat leakage during the entire superconducting coil excitation process is reduced, which in turn reduces the quenching failure problem that may be caused by excessive heat at the current lead joint of the superconducting coil and improves the stability of the superconducting coil excitation process.

[0038] (2) The superconducting bare wires of each component do not need to be bent or wrapped.

[0039] Since the strength of the superconducting bare wire weakens after the insulation layer is removed, in order to avoid damage to the superconducting wire due to bending, the present invention sets the superconducting bare wire inside a tubular structure, which only needs to be placed parallel to the current lead. The superconducting bare wire of each component does not need to be bent or wrapped.

[0040] (3) Simple welding and disassembly

[0041] During welding, the solder is slowly poured into the tubular structure from the top and heated and cooled. During disassembly, the welded joint is heated to the point where the solder melts. The melted solder will flow out naturally from the bottom and will not affect the secondary fabrication of the joint. Attached Figure Description

[0042] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the embodiments of the invention and illustrate the principles of the invention together with the textual description. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0043] Figure 1 An exploded view of a current lead connector structure provided according to an embodiment of the present invention is shown;

[0044] Figure 2 A schematic diagram of a current lead connector structure according to an embodiment of the present invention is shown.

[0045] Figure 3 A flowchart illustrating a welding method for a current lead connector structure provided according to an embodiment of the present invention is shown.

[0046] The above figures include the following reference numerals:

[0047] 10. Current lead; 11. Groove; 20. Fixing component;

[0048] 30. Superconducting wires; 31. Superconducting bare wires; 32. Superconducting busbars;

[0049] 40. Insulation layer. Detailed Implementation

[0050] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0052] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0053] like Figure 1 and Figure 2 As shown, the present invention provides a current lead connector structure, the structure including a current lead 10, a fixing component 20, a superconducting wire 30, and solder;

[0054] The first end of the current lead 10 is provided with a groove 11 along its own axis.

[0055] The fixing component 20 is a U-shaped plate structure adapted to the groove 11. The fixing component 20 is upside down on the groove 11 to form a tubular structure with open ends. The length of the fixing component 20 is less than the width of the groove 11.

[0056] The first segment of the superconducting wire 30 is a bare superconducting wire 31 with the cladding layer removed, and the second segment is a superconducting busbar 32 with the cladding layer intact. The bare superconducting wire 31 is disposed inside the tubular structure, and the superconducting busbar 32 is disposed outside the tubular structure. The length of the bare superconducting wire 31 is less than the length of the fixing component 20.

[0057] The solder is laid inside the tubular structure and completely submerges the superconducting bare wire 31. By heating and cooling the solder, the superconducting bare wire 31, the first end of the current lead 10 and the solder are fused together to achieve the welding of the superconducting wire 30 and the current lead 10.

[0058] The width direction of the groove 11 is the same as the axial direction of the current lead 10.

[0059] The current lead connector structure of the present invention has the following advantages compared with the prior art:

[0060] (1) Low contact resistance

[0061] During the welding process, the superconducting wires 30 and current leads 10 of each component can make full contact with their bare superconducting wires 31 by a large amount of solder, avoiding gaps inside each solder joint and preventing the phenomenon of incomplete soldering. This greatly reduces the contact resistance and avoids the problem of excessive Joule heating at the low-temperature end of the traditional pull-out current lead 10. This reduces the heat leakage during the entire superconducting coil excitation process, thereby reducing the superconducting coil's potential loss of quench due to excessive heat at the current lead 10 connector and improving the stability of the superconducting coil excitation process.

[0062] (2) The superconducting bare wires 31 of the superconducting wires 30 of each component do not need to be bent or wrapped.

[0063] Since the strength of the superconducting bare wire 31 weakens after the insulation layer 40 is removed, in order to avoid damage to the superconducting wire 30 due to bending, the present invention sets the superconducting bare wire 31 inside the tubular structure, which only needs to be placed parallel to the current lead 10. The superconducting bare wire 31 of the superconducting wire 30 of each component does not need to be bent or wrapped.

[0064] (3) Simple welding and disassembly

[0065] During welding, the solder is slowly poured into the tubular structure from the top and heated and cooled. During disassembly, the welded joint is heated to the point where the solder melts. The melted solder will flow out naturally from the bottom and will not affect the secondary fabrication of the joint.

[0066] According to one embodiment of the present invention, in order to facilitate solder pouring, the depth of the groove 11 gradually increases from the first end of the current lead 10 to the second end of the current lead 10, wherein the depth direction of the groove 11 is the radial direction of the current lead 10.

[0067] According to one embodiment of the present invention, there are multiple grooves 11, each groove 11 is arranged at intervals along the circumference of the current lead 10, and the number of fixing members 20 and the number of superconducting wires 30 are the same as the number of grooves 11.

[0068] The above setup facilitates the welding of the current lead 10 to the superconducting wires 30 led out from multiple liquid helium-immersed superconducting coils, allowing multiple superconducting coils to be tested at once. This reduces the number of tests and the amount of liquid helium used, thus saving costs.

[0069] According to one embodiment of the present invention, the fixing component 20 includes a plurality of U-shaped plate structures connected end to end.

[0070] The above settings prevent the solder from solidifying during the pouring process, thus avoiding the situation where the tubular structure cannot be completely filled.

[0071] The fixing component 20 can be made of high-purity oxygen-free copper.

[0072] According to one embodiment of the present invention, the structure further includes an insulating layer 40, which wraps around the outside of the second end of the current lead 10 to achieve insulation between the current lead 10 and the room temperature Dewar.

[0073] Specifically, the insulating layer 40 may be made of epoxy resin.

[0074] According to one embodiment of the present invention, the length of the superconducting bare wire 31 ranges from 175 to 185 mm.

[0075] According to one embodiment of the present invention, the current lead 10 is a copper tube. The copper tube is used to carry the excitation current.

[0076] According to one embodiment of the present invention, the wrapping layer is an insulating wrapping layer or a metal wrapping layer.

[0077] According to one embodiment of the present invention, the solder may be Wood's alloy.

[0078] The current lead connector structure of this invention is simple to manufacture, has a simple welding process, facilitates secondary fabrication of superconducting connectors, has good contact effect, low contact resistance, low heat generation, low heat leakage, stable performance, reliable operation, and long service life. It maximizes the stability of the lead wire of the low-temperature superconducting coil, reduces the risk of superconducting coil losing quench during excitation testing, and improves the stability of the superconducting coil excitation process.

[0079] like Figure 3 As shown, the present invention also provides a welding method for a current lead connector structure, wherein any of the above-mentioned current lead connector structures is obtained by means of the method, the method comprising:

[0080] S10. Remove the cladding layer from the first segment of the superconducting wire 30 to obtain a superconducting bare wire 31 of a preset length.

[0081] S20. Place the superconducting bare wire 31 in the groove 11 of the current lead 10, and invert the fixing component 20 on the groove 11 to form a tubular structure that wraps the superconducting bare wire 31.

[0082] S30. Place the current lead 10 with the first end facing down and the second end facing up, and seal the lower port of the tubular structure with a sealing component.

[0083] S40. Pour solder into the tubular structure from the upper end until the solder fully submerges the superconducting bare wire 31;

[0084] S50. Heat the solder inside the tubular structure to melt it until it is completely fused together.

[0085] S60. Cool the molten solder inside the tubular structure to solidify the solder, remove the sealing component, and complete the welding of the superconducting wire 30 and the current lead 10.

[0086] The welding method for the current lead connector structure of the present invention has the following advantages compared with the prior art:

[0087] (1) Low contact resistance

[0088] During the welding process, the superconducting wires 30 and current leads 10 of each component can make full contact with their bare superconducting wires 31 by a large amount of solder, avoiding gaps inside each solder joint and preventing the phenomenon of incomplete soldering. This greatly reduces the contact resistance and avoids the problem of excessive Joule heating at the low-temperature end of the traditional pull-out current lead 10. This reduces the heat leakage during the entire superconducting coil excitation process, thereby reducing the superconducting coil's potential loss of quench due to excessive heat at the current lead 10 connector and improving the stability of the superconducting coil excitation process.

[0089] (2) The superconducting bare wires 31 of the superconducting wires 30 of each component do not need to be bent or wrapped.

[0090] Since the strength of the superconducting bare wire 31 weakens after the insulation layer 40 is removed, in order to avoid damage to the superconducting wire 30 due to bending, the present invention sets the superconducting bare wire 31 inside the tubular structure, which only needs to be placed parallel to the current lead 10. The superconducting bare wire 31 of the superconducting wire 30 of each component does not need to be bent or wrapped.

[0091] (3) Simple welding and disassembly

[0092] During welding, the solder is slowly poured into the tubular structure from the top and heated and cooled. During disassembly, the welded joint is heated to the point where the solder melts. The melted solder will flow out naturally from the bottom and will not affect the secondary fabrication of the joint.

[0093] According to one embodiment of the present invention, in S10 of the present invention, the preset length of the superconducting bare wire 31 can be set to 180 mm.

[0094] According to one embodiment of the present invention, in S30 of the present invention, the sealing component may be made of putty; the current lead 10 may be made of copper tubing.

[0095] According to one embodiment of the present invention, in S40, when pouring solder, a thin rod can be used to guide the flow and pour it slowly. Simultaneously, to prevent the tubular structure from shaking, clamps can be used to hold the tubular structure in place. The solder can be Wood's alloy.

[0096] Furthermore, when the fixing component 20 includes multiple U-shaped plate structures connected end to end, the first U-shaped plate structure is filled first, then the second U-shaped plate structure is inverted and inserted, then the second U-shaped plate structure is filled and then the third U-shaped plate structure is inverted and inserted, and so on, until the solder completely submerges the superconducting bare wire 31.

[0097] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0098] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0099] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A current lead connector structure, characterized in that, The structure includes current leads (10), fixing components (20), superconducting wires (30), and solder; The first end of the current lead (10) is provided with a groove along its own axis; The fixing component (20) is a U-shaped plate structure adapted to the groove. The fixing component (20) is upside down on the groove to form a tubular structure with open ends. The length of the fixing component (20) is less than the width of the groove. The first segment of the superconducting wire (30) is a bare superconducting wire (31) with the cladding layer removed, and the second segment is a superconducting busbar (32) with the cladding layer removed. The bare superconducting wire (31) is disposed inside the tubular structure, and the superconducting busbar (32) is disposed outside the tubular structure. The length of the bare superconducting wire (31) is less than the length of the fixing component (20). The solder is laid inside the tubular structure and completely submerges the superconducting bare wire (31). By heating and cooling the solder, the superconducting bare wire (31), the first end of the current lead (10) and the solder are fused together to achieve the welding of the superconducting wire (30) and the current lead (10). Wherein, the width direction of the groove is the axial direction of the current lead (10); The depth of the groove gradually increases from the first end of the current lead (10) to the second end of the current lead (10), wherein the depth direction of the groove is radial to the current lead (10); there are multiple grooves, each groove is spaced apart circumferentially along the current lead (10), and the number of fixing components (20) and the number of superconducting wires (30) are the same as the number of grooves; the fixing component (20) includes multiple U-shaped plate structures connected end to end.

2. The structure according to claim 1, characterized in that, The structure also includes an insulating layer (40) that wraps around the outside of the second end of the current lead (10).

3. The structure according to claim 1, characterized in that, The length of the superconducting bare wire (31) ranges from 175 to 185 mm.

4. The structure according to claim 1, characterized in that, The current lead (10) is a copper tube.

5. The structure according to claim 1, characterized in that, The wrapping layer is an insulating wrapping layer or a metal wrapping layer.

6. A welding method for a current lead connector structure, characterized in that, The method described above is used to obtain any current lead connector structure according to claims 1-5, the method comprising: The first segment of the superconducting wire (30) is de-wrapped to obtain a superconducting bare wire (31) of a preset length. The superconducting bare wire (31) is placed in the groove of the current lead (10), and the fixing component (20) is upside down on the groove to form a tubular structure that wraps the superconducting bare wire (31); Place the first end of the current lead (10) downward and the second end upward, and seal the lower port of the tubular structure with a sealing component; The solder is poured in from the upper end of the tubular structure until the solder fully submerges the superconducting bare wire (31). The solder inside the tubular structure is heated to melt it until it is completely fused together. The molten solder inside the tubular structure is cooled to solidify, the sealing component is removed, and the welding of the superconducting wire (30) and the current lead (10) is completed.

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