Welding method for superconducting layer of intermediate joint of superconducting cable

Abstract

The invention discloses a superconducting cable intermediate joint superconducting layer welding method, which comprises the following steps: respectively stripping the ends of two sections of superconducting cable cores to be connected, and exposing a plurality of single superconducting tapes in the ends of the two sections of superconducting cable cores; a plurality of additional superconducting short tapes are used for sequentially bridging the plurality of single superconducting tapes at the ends of the two sections of superconducting cable cores, and single pre-welding is carried out respectively; welding flux is injected into gaps among all the strips subjected to single body pre-welding; wrapping a copper sheath outside the bridging section injected with the welding flux; and a welding tool is arranged outside the copper sheath, the welding tool is heated, the strip and the welding flux of the bridging section are heated through the copper sheath, and the copper sheath and the strip inside the copper sheath are welded into a whole. According to the superconducting cable intermediate joint superconducting layer welding method, the pre-welding strength of a single strip can be improved through integral unified welding after single pre-welding; welding strength is reduced, welding efficiency is improved, and cost is easy to control.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting cables, and particularly relates to a method for welding a superconducting layer of a superconducting cable intermediate joint. Background Art

[0002] Common superconducting layer welding methods include butt joint, lap joint and bridge joint. However, due to the relatively complex laminated composite structure of superconducting tapes, the production of butt joints is particularly difficult. Moreover, since the superconducting core contact surface of such joints is relatively small and the transmitted current is also relatively small, it is not very commonly used. Lap joints are not symmetric in geometric and electrical properties and have protrusions, affecting the overall flatness. The mechanical stability of bridge joints is slightly poor. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for welding a superconducting layer of a superconducting cable intermediate joint, which can improve the strength of pre-welding of a single tape through overall unified welding after single-body pre-welding; reduce the welding strength and improve the welding efficiency, and is easy to control costs.

[0004] To solve the above technical problems, the present invention provides a method for welding a superconducting layer of a superconducting cable intermediate joint, including the following steps: S1, stripping the ends of two superconducting cable cores to be connected respectively to expose multiple single superconducting tapes inside the ends of the two superconducting cable cores; S2, using multiple additional superconducting short tapes to sequentially bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores, and performing single-body pre-welding respectively; S3, injecting solder into the gaps between all the tapes after single-body pre-welding; S4, wrapping a copper sleeve outside the bridged section where the solder is injected; S5, installing a welding tool outside the copper sleeve, heating the welding tool, and heating the tapes and the solder in the bridged section through the copper sleeve to weld the copper sleeve and the tapes inside it into one body.

[0005] Among them, the step of using multiple additional superconducting short tapes to sequentially bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores includes: the additional superconducting short tapes are respectively lapped on the two single superconducting tapes to be connected on both sides in a symmetric manner on both sides, and the step of performing soldering with tin solder, wherein: the front sides of the additional superconducting short tapes and the front sides of the two single superconducting tapes are bridged together to reduce the resistance of the joint.

[0006] Among them, the length dimension range of the additional superconducting short tapes is between 100 mm and 140 mm.

[0007] Among them, the step of using multiple additional superconducting short tapes to sequentially bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores further includes: winding at least one layer of polytetrafluoroethylene plastic tape on the side of the additional superconducting short tapes facing the two single superconducting tapes for welding to prevent the heat and leaked tin of welding from affecting the functional layer below the single superconducting tapes.

[0008] Among them, the thickness dimension range of the polytetrafluoroethylene plastic tape is 0.1 mm - 0.2 mm, and the width dimension of the polytetrafluoroethylene plastic tape is 10 - 15 mm larger than the width dimension of the additional superconducting short tape.

[0009] Among them, the steps of wrapping the copper jacket outside the bridging section where the solder is injected include the following: applying solder to the inner side of the copper jacket facing the bridging strip; the length dimension of the copper jacket is smaller than the length dimension of the additional superconducting short tape, and symmetrical length dimensions of the additional superconducting short tape are exposed on the opposite sides of the copper jacket; the step of fixing the copper jacket with polyamide tape.

[0010] Among them, the steps of installing the welding tooling outside the copper jacket include the following: using two semi - hollow cylinders to fit and dock for fixing the copper jacket; inserting heating rods and thermocouples into multiple through - holes of the semi - hollow cylinders respectively; heating the semi - hollow cylinders at a given temperature to melt the solder inside the copper jacket.

[0011] Among them, the structures of the two semi - hollow cylinders are set to be symmetrical.

[0012] Implementing the superconducting layer welding method for the superconducting cable intermediate joint of the present invention has the following beneficial effects: The superconducting layer welding method for the superconducting cable intermediate joint includes the following steps: stripping the ends of the two superconducting cable cores to be connected respectively to expose multiple single - body superconducting strips inside the ends of the two superconducting cable cores; using multiple additional superconducting short tapes to bridge the multiple single - body superconducting strips at the ends of the two superconducting cable cores in sequence and performing single - body pre - welding respectively; injecting solder into the gaps between all the tapes after single - body pre - welding; wrapping a copper jacket outside the bridging section where the solder is injected; S5, installing welding tooling outside the copper jacket, heating the welding tooling, heating the strips and solder in the bridging section through the copper jacket, and welding the copper jacket and the strips inside it into one body, which can improve the strength of the single - strip pre - welding through overall welding after single - body pre - welding; reducing the welding strength and improving the welding efficiency, and being easy to control the cost. Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0014] Figure 1 It is a structural schematic diagram of the single - body pre - welding of the superconducting layer welding method for the superconducting cable intermediate joint in the embodiment of the present invention.

[0015] Figure 2It is a schematic structural diagram of the additional superconducting short strip in the embodiment of the present invention for successively bridging multiple single superconducting strip materials at the ends of two superconducting cable cores.

[0016] Figure 3 It is a schematic structural diagram of a welding tooling in the superconducting layer welding method of the superconducting cable intermediate joint in the embodiment of the present invention.

[0017] Figure 4 It is a schematic structural diagram of the overall unified welding in the superconducting layer welding method of the superconducting cable intermediate joint in the embodiment of the present invention. Specific embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0019] As Figures 1-4 shown, it is the first embodiment of the superconducting layer welding method of the superconducting cable intermediate joint of the present invention.

[0020] The superconducting layer welding method in this embodiment includes the following steps: S1. Strip the ends of the two superconducting cable cores to be connected respectively to expose multiple single superconducting strip materials inside the ends of the two superconducting cable cores; S2. Use multiple additional superconducting short strips to successively bridge the multiple single superconducting strip materials at the ends of the two superconducting cable cores and perform single-body pre-welding respectively; S3. Inject solder into the gaps between all the strip materials after single-body pre-welding; S4. Wrap a copper sheath outside the bridged section where the solder is injected; S5. Install a welding tooling outside the copper sheath, heat the welding tooling, and heat the strip materials and the solder in the bridged section through the copper sheath to weld the copper sheath and the strip materials inside it into one body.

[0021] Specifically, as Figure 1 shown, in step S1, 1a and 1b are the two ends of the two superconducting cable cores to be connected. The cable cores can be single-core type, three-phase coaxial type, or DC single-pole type, bipolar coaxial type, etc. The differences among the above multiple different configurations lie in the configuration differences of the functional layers, and the superconducting layers among them are all axially symmetric structures with spiral winding.

[0022] This embodiment takes the connection of a single-core superconducting layer as an example. After stripping other functional layers such as insulation, multiple superconducting tapes 2a and 2b inside the ends of two superconducting cable cores are exposed. Among them, the overall cross-sectional shape of the arrangement of multiple superconducting tapes 2a and multiple superconducting tapes 2b is circular.

[0023] In step S2, in the monomer pre-welding stage, an additional superconducting tape short tape 3 is used, and the tapes at similar angles at both ends 2a and 2b are welded in turn in a bridging manner. This method can well avoid the connection scheme of using single tapes for corresponding connection and the need for all tapes to be aligned. Implementing monomer pre-welding does not need to ensure the consistency of the spiral angles of the energized conductor layers of the two superconducting cables, which can be compensated for in the subsequent overall welding.

[0024] Among them, the steps of successively bridging multiple monomer superconducting tapes 2a and 2b at the ends of two superconducting cable cores using multiple additional superconducting short tapes 3 include: the additional superconducting short tape 3 is respectively lapped on the two monomer superconducting tapes 2a and 2b to be connected on both sides in a symmetric manner on both sides, and then the step of soldering is carried out.

[0025] In this embodiment, the melting point temperature of the solder used should not be higher than the solder temperature of the superconducting tape. The ReBCO coated superconducting tape has an asymmetric structure on both sides. The side closer to the superconducting layer is denoted as the "front side", and the opposite side is denoted as the "back side". When lapping, the front side of the additional superconducting short tape 3 should be welded together with the front sides of the monomer superconducting tapes 2a and 2b to reduce the joint resistance. Further, the front sides of the additional superconducting short tape 3 and the two monomer superconducting tapes are bridged together to reduce the resistance of the joint.

[0026] Preferably, the length dimension range of the additional superconducting short tape is between 100 mm and 140 mm.

[0027] Further, the steps of successively bridging multiple monomer superconducting tapes at the ends of two superconducting cable cores using multiple additional superconducting short tapes also include: the additional superconducting short tape 3 is wound around at least one layer of polytetrafluoroethylene plastic tape (2 layers in this embodiment, or more than 2 layers can also be wound) on the side facing the welding of the two monomer superconducting tapes, so as to prevent the heat and leaking solder of the welding from affecting the functional layer below the monomer superconducting tape.

[0028] Among them, the thickness dimension range of the polytetrafluoroethylene plastic tape is between 0.1 mm and 0.2 mm, and the width dimension of the polytetrafluoroethylene plastic tape is 10 - 15 mm larger than the width dimension of the additional superconducting short tape.

[0029] Further, in step S4, after the monomer welding is completed and solder is injected into the gap, a copper sleeve 6 is wrapped around the outside of the bridging section.

[0030] In this embodiment, the thickness of the copper sleeve 6 is preferably 0.2 mm, and the width is preferably 5-10 mm shorter than the additional superconducting tape of the bridging section. The length of the copper sleeve 6 is preferably 0.5-1 mm less than the outer perimeter of the tape of the bridging section.

[0031] Preferably, the step of wrapping the copper sleeve 6 outside the bridging section into which solder is injected includes the following: applying tin solder to the inner side of the copper sleeve 6 facing the bridging tape; the length dimension of the copper sleeve 6 is smaller than the length dimension of the additional superconducting short tape, and symmetrical lengths of the additional superconducting short tape are exposed on the opposite sides of the copper sleeve 6; the step of fixing the copper sleeve with polyamide tape.

[0032] The function of setting the copper sleeve 6 is as follows: The copper sleeve 6 not only plays roles such as fixing the bridging superconducting tape, transferring heat, and preventing tin leakage during welding. When the superconducting cable is operating, it can also provide a current transfer path and heat capacity, which helps to improve the thermal stability of the joint part.

[0033] Further, the step of installing the welding tooling 7 outside the copper sleeve 6 includes the following: using two semi-hollow cylinders 7a and 7b to fit and dock to fix the copper sleeve 6; inserting heating rods and thermocouples into a plurality of through holes 9 of the semi-hollow cylinders 7a and 7b respectively; heating the semi-hollow cylinders at a given temperature, thereby melting the solder inside the copper sleeve 6.

[0034] The function of setting the welding tooling 7 is as follows: Through the pressure applied by the welding tooling 7, the strength of pre-welding of a single tape can be improved, and the joint resistance can be reduced.

[0035] During implementation, after the welding tooling 7 is fixed, after inserting heating rods and thermocouples into a plurality of through holes 9 of the semi-hollow cylinders 7a and 7b, the power supply can be started to heat the welding tooling 7 at a given temperature. The welding tooling 7 heats the tape and solder of the bridging section through the copper sleeve 6. Through this process, the solder inside the copper sleeve 6 will melt, and the inner tape and the copper sleeve 6 will be welded into one body, thereby completing the overall welding.

[0036] Preferably, the structures of the two semi-hollow cylinders 7a and 7b are set to be symmetrical. In order to enable the two semi-hollow cylinders 7a and 7b to fit and assemble better, symmetrical step structures 8 are provided on the contact surfaces of the two semi-hollow cylinders 7a and 7b.

[0037] In this embodiment, the length and diameter of the through hole 9 are adapted to the heating rod. The number of through holes 9 can be determined according to the heating power. Preferably, the through holes 9 are distributed in a substantially symmetrical manner on the circumference. Among them, at least one hole is left for installing a thermocouple thermometer for real-time measurement of the temperature of the heating tooling.

[0038] In the specific implementation of the superconducting layer welding method for the superconducting cable intermediate joint in this embodiment, since after monomer pre-welding, overall unified welding is carried out through the copper sheath 6 and the welding tooling 7. In this connection mode, the conditions for the multi-strand monomer superconducting tapes 2a and 2b at the ends of the two superconducting cable cores to be bridged in sequence are relaxed. The relative superconducting tapes do not need to be completely aligned, and the coincidence degree and error tolerance of the overlapping angle are increased. For example, when the spiral angles of the energized conductor layers of the two superconducting cables to be connected are 18° and 22° respectively, monomer pre-welding can still be carried out first.

[0039] The superconducting layer welding method for the superconducting cable intermediate joint in this embodiment, the superconducting layer welding method for the superconducting cable intermediate joint includes the following steps: stripping the ends of the two superconducting cable cores to be connected respectively to expose the multi-strand monomer superconducting tapes inside the ends of the two superconducting cable cores; using multiple additional superconducting short tapes to bridge the multi-strand monomer superconducting tapes at the ends of the two superconducting cable cores in sequence, and carrying out monomer pre-welding respectively; injecting solder into the gaps between all the tapes after monomer pre-welding; wrapping a copper sheath around the outside of the bridged section where the solder is injected; S5, installing welding tooling outside the copper sheath, heating the welding tooling, heating the tapes and the solder in the bridged section through the copper sheath, and welding the copper sheath and the tapes inside it into one body, which can improve the strength of the pre-welding of a single tape through overall unified welding after monomer pre-welding; reduce the welding strength and improve the welding efficiency, and it is easy to control the cost.

Claims

1. A superconducting layer welding method for a superconducting cable joint, characterized in that, It includes the following steps: S1. Strip the ends of the two superconducting cable cores to be connected respectively to expose multiple single superconducting tapes inside the ends of the two superconducting cable cores; S2. Use multiple additional superconducting short tapes to bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores in sequence, and perform single pre-welding respectively; S3. Inject solder into the gaps between all the tapes after single pre-welding; S4. Wrap a copper sleeve outside the bridged section where the solder is injected; S5. Install a welding tool outside the copper sleeve, heat the welding tool, and heat the tapes and solder in the bridged section through the copper sleeve to weld the copper sleeve and the tapes inside it into one body.

2. The superconducting layer welding method of the superconducting cable intermediate joint according to claim 1, wherein The step of using multiple additional superconducting short tapes to bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores in sequence includes: The additional superconducting short tapes are respectively lapped on the two single superconducting tapes to be connected on both sides in a symmetric manner on both sides, and the step of welding with soldering, wherein: the front surfaces of the additional superconducting short tapes and the two single superconducting tapes are bridged together to reduce the resistance of the joint.

3. The superconducting layer welding method of the superconducting cable intermediate joint according to claim 2, wherein, The length dimension range of the additional superconducting short tapes is between 100 mm and 140 mm.

4. The superconducting layer welding method of the superconducting cable intermediate joint as claimed in claim 2, wherein The step of using multiple additional superconducting short tapes to bridge the multiple single superconducting tapes at the ends of the two superconducting cable cores in sequence further includes: At least one layer of polytetrafluoroethylene plastic tape is wound on the side of the additional superconducting short tape facing the two single superconducting tapes for welding to prevent the heat and leaking solder during welding from affecting the functional layer below the single superconducting tape.

5. The superconducting layer welding method of the superconducting cable intermediate joint according to claim 4, wherein The thickness dimension range of the polytetrafluoroethylene plastic tape is between 0.1 mm and 0.2 mm, and the width dimension of the polytetrafluoroethylene plastic tape is 10 - 15 mm larger than the width dimension of the additional superconducting short tape.

6. The superconducting layer welding method of the superconducting cable intermediate joint as described in claim 1, characterized in that The step of wrapping a copper sleeve outside the bridged section where the solder is injected includes the following: Apply soldering on the inner side of the copper sleeve facing the bridged tapes; The length dimension of the copper sleeve is smaller than the length dimension of the additional superconducting short tape, and symmetric lengths of the additional superconducting short tapes are exposed on the opposite sides of the copper sleeve; The step of fixing the copper sleeve with polyamide tape.

7. The superconducting layer welding method for the superconducting cable intermediate joint according to claim 1, characterized in that, The step of installing a welding tool outside the copper sleeve includes the following: Use two semi-hollow cylinders to fit and dock to fix the copper sleeve; Insert heating rods and thermocouples into multiple through holes of the semi-hollow cylinders respectively; Heat the semi-hollow cylinders at a given temperature to melt the solder in the copper sleeve.

8. The superconducting layer welding method for the superconducting cable intermediate joint according to claim 1, characterized in that, The structures of the two semi-hollow cylinders are set to be symmetric.

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