CN112117051A - Encapsulation strengthening method of REBCO conductor and drawing die in encapsulation - Google Patents
Encapsulation strengthening method of REBCO conductor and drawing die in encapsulation Download PDFInfo
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- CN112117051A CN112117051A CN202010960097.6A CN202010960097A CN112117051A CN 112117051 A CN112117051 A CN 112117051A CN 202010960097 A CN202010960097 A CN 202010960097A CN 112117051 A CN112117051 A CN 112117051A
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- 239000004020 conductor Substances 0.000 title claims abstract description 150
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000005728 strengthening Methods 0.000 title claims abstract description 21
- 238000005538 encapsulation Methods 0.000 title claims description 9
- 229910052751 metal Inorganic materials 0.000 claims abstract description 96
- 239000002184 metal Substances 0.000 claims abstract description 96
- 238000004806 packaging method and process Methods 0.000 claims abstract description 16
- 238000004140 cleaning Methods 0.000 claims description 17
- 238000005520 cutting process Methods 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 239000010949 copper Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 7
- 230000000149 penetrating effect Effects 0.000 claims description 7
- 238000002791 soaking Methods 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 238000007664 blowing Methods 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 244000137852 Petrea volubilis Species 0.000 claims description 3
- 229910001128 Sn alloy Inorganic materials 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical group [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 claims description 3
- 238000003303 reheating Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 238000001125 extrusion Methods 0.000 abstract description 12
- 239000010410 layer Substances 0.000 description 10
- 238000003466 welding Methods 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000002887 superconductor Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000011185 multilayer composite material Substances 0.000 description 1
- 238000012858 packaging process Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
- H01B12/02—Superconductive or hyperconductive conductors, cables, or transmission lines characterised by their form
- H01B12/06—Films or wires on bases or cores
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
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Abstract
The invention belongs to the technical field of high-temperature superconduction, and particularly relates to a packaging strengthening method of an REBCO conductor and a drawing die in packaging. The central hole consisting of the outward-expanding part and the middle part is designed on the drawing die, the triangular bulge is arranged on the middle hole, the groove is drawn on the surface of the REBCO round wire conductor, the extrusion stress in the drawing process of the packaging metal pipe is fully absorbed, the condition that the REBCO strip damages the superconducting layer structure due to the overlarge extrusion stress is avoided, the superconductivity is lost, meanwhile, the extrusion stress in the drawing process of the packaging metal pipe can be fully absorbed, and the condition that the REBCO strip in the conductor damages the superconducting layer structure due to the overlarge extrusion stress is avoided, and the superconductivity is lost.
Description
Technical Field
The invention belongs to the technical field of high-temperature superconduction, and particularly relates to a packaging strengthening method and a drawing die for a REBCO (second-generation high-temperature superconduction) conductor.
Background
The temperature superconducting strip has the operating temperature and the critical magnetic field which are far higher than those of low-temperature superconductors, and provides a better choice for building a strong magnetic field magnet, such as a fusion reactor magnet, an accelerator magnet, a detector magnet and the like. The REBCO high-temperature superconductor is a strip-shaped multilayer composite material, the current carrying capacity of a single strip is limited, and a plurality of REBCO strips need to be connected in parallel for use in order to meet the requirement of high-current application. The ribbon structure makes REBCO strip can not be twisted and wound like the traditional cable, so the REBCO strip needs to be wound on a round core rod or made into a round wire after being stacked, and then the REBCO round wire conductor is twisted as a strand wire to be made into a large-current conductor.
The REBCO strip is formed by compounding a substrate layer, a superconducting layer, a stabilizing layer, a protective layer and other multi-layer materials, although the REBCO strip has high axial tensile strength and vertical compressive strength, the superconducting layer is made of brittle ceramic materials and is connected with the substrate material providing mechanical strength in a fragile manner, so that the shear force and stripping force bearing capacity of the conductor after stacking welding is poor. The REBCO conductor inevitably bears huge stress during the manufacturing process of the magnet and when the magnet runs in a high-current and high-magnetic-field environment, so that the REBCO conductor needs to be packaged and strengthened to have enough mechanical performance.
The existing main methods for preparing the REBCO conductor into the round wire comprise the following steps: thin wires or thin strips are wrapped (copper wires, copper foils, aluminum foils, soldering wires and the like), and the method is low in preparation efficiency and low in mechanical strength; the REBCO round wire conductor prepared by the three methods inevitably leaves a welding seam, the welding seam is easy to crack under huge stress, and the mechanical property of the REBCO round wire conductor is seriously limited.
Disclosure of Invention
The invention aims to provide a packaging strengthening method of a REBCO conductor and a drawing die in packaging, which can improve the mechanical strength and current density of the REBCO conductor and increase the length of the REBCO conductor so as to meet the application requirements of bearing huge current (more than 10kA) and stress (more than 100 MPa).
The technical scheme of the invention is as follows:
a package strengthening method of REBCO conductors comprises the following steps:
1) material preparation
1.1) cleaning the REBCO round wire conductor, wherein the outer diameter of the REBCO round wire conductor is D;
1.2) preparing a metal pipe, and processing the end part of the metal pipe into a U-shaped structure;
cutting off two opposite sides of one end of the metal pipe along the direction of the pipe wall to form four cut planes and two cut bottoms, wherein the two cut planes positioned on one side are positioned on the same plane, and a U-shaped structure is formed at the end part of the metal pipe;
1.3) cleaning the cut metal tube;
2) processing triangular groove outside REBCO round wire conductor
2.1) determining drawing die for round wire conductor
The main body of the round wire conductor drawing die is of a cylindrical structure, a central hole is machined along the central axial direction, two ends of the central hole are respectively provided with an external expanding part with a small inside and a large outside, the middle part is provided with a middle part with a constant inner diameter, and the middle part of the central hole is positioned in the middle of the round wire conductor drawing die; symmetrical triangular bulges are arranged inside the central hole;
2.2) the REBCO round wire conductor enters from the outward expansion part at one end of the central hole, passes through the round wire conductor drawing die, and the connecting line of the section vertexes of the triangular bulges at the same position is kept to be vertical to the surface of the REBCO strip of the round wire conductor to form a triangular groove;
3) threading REBCO round wire conductor into metal pipe and installing clamp
3.1) penetrating the REBCO round wire conductor with the triangular groove into a metal tube,
3.2) clamping the U-shaped structure of the metal pipe by using a clamp, wherein the clamping direction is vertical to the surface of the REBCO strip of the REBCO round wire conductor;
4) drawing and forming the metal tube penetrating into the REBCO round wire conductor
The secondary drawing die is formed by two-time drawing, the selected secondary drawing die is a cylindrical structure processed with a central hole, the central hole is provided with an outward-expanding part and a middle part, the middle part is positioned in the cylindrical middle part, the taper of the outward-expanding part of the two-time drawing die is the same, but the diameter of the middle part of the second-time drawing die is smaller than that of the middle part of the first-time drawing die; heating the metal pipe to 180-250 ℃ before each drawing;
and naturally cooling the metal pipe, cutting off the part of the metal pipe clamped by the clamp and the part of the metal pipe not filled with the REBCO round wire conductor in the drawing process, and finally forming the packaged and reinforced REBCO round wire conductor.
The REBCO round wire conductor in the step 1.1) is composed of a REBCO strip and metal coated outside the REBCO strip, and the outer diameter D is 1.5-9 mm.
The diameter D of the REBCO round wire conductor is 1.1D-1.3D, the wall thickness is 0.05D-0.2D, and the metal coated outside is lead-tin alloy Sn63Pb 37.
In the step 1.1), 1200-mesh sand paper is adopted to remove oil stains and oxidation films on the surface of the REBCO round wire conductor, then the REBCO round wire conductor is cleaned by alcohol, and the REBCO round wire conductor is blown dry by normal-temperature wind for standby.
In the step 1.2), the cutting thickness is 0.12-0.34D and the cutting length is 18D-50D when the U-shaped structure is formed.
In the step 1.3), oil stains on the inner and outer surfaces of the cut metal pipe in the step 1.2 are cleaned by using alcohol, then the metal pipe is soaked by using a cleaning brightener to remove a surface oxide layer, and after the soaking is finished, the metal pipe is washed clean by using clean water, and the inner and outer walls are dried by blowing at normal temperature for later use.
The cleaning brightener 916 copper cleaning brightener, and the soaking time is 20-120 s.
The round wire conductor drawing die is made of hard alloy, the diameter of the middle part is 1.01D-1.03D, and the taper of the outward expansion part is 20-30 degrees.
The triangular bulges are in a pair of convex long-strip-shaped structures distributed in the radial direction, extend along the generatrix direction of the outward-expanding part cone and continue to extend in the middle part, the angle of the triangular bulges is 60 degrees, and the height of the triangular bulges is 0.1-0.15D.
The diameter of the central hole is 3.25mm, and the height of the triangular bulge is 0.4 mm.
In the step 3.1), the end part of the REBCO round wire conductor is flush with the end part of the metal pipe, and the plane of the cut at the end part of the metal pipe is vertical to the surface of the REBCO strip in the REBCO round wire conductor.
The step 4) is specifically as follows:
4.1) making a first drawing die
The taper of the flaring part of the first-pass drawing die is 20-30 degrees, and the diameter of the middle part of the first-pass drawing die is 1.11D-1.42D;
4.2) heating the metal pipe to 180-250 ℃, and passing through a central hole 4-1 of the first-pass drawing die to draw the metal pipe at a drawing speed of not more than 0.2 m/s;
4.3) manufacturing a second pass drawing die
The taper of the outward-expanding part of the second-pass drawing die is 20-30 degrees, and the diameter of the middle part of the second-pass drawing die is 1.102D-1.405D;
and 4.4) reheating the metal pipe to enable the temperature of the metal pipe to reach 180-250 ℃, and drawing the metal pipe by penetrating through the central hole of the second-pass drawing die at a drawing speed of not more than 0.1 m/s.
In the step 4.1), the taper of the flaring part of the first-pass drawing die is 20-30 degrees, and the diameter of the middle part of the first-pass drawing die is 4.25 mm; in the step 4.2), the temperature is heated to 180-250 ℃, and the drawing speed is 0.01-0.15 m/s; in the step 4.3), the taper of the outward-expanding part of the second-pass drawing die is 20-30 degrees, and the diameter of the middle part of the second-pass drawing die is 1.102D-1.405D; in the step 4.4), the metal tube is heated to 200 ℃ and the drawing speed is 0.01-0.05 m/s.
The metal pipe is made of T1 copper.
A drawing die in REBCO conductor packaging is of a cylindrical structure, a central hole is machined in the axial direction of a center, two ends of the central hole are outer expanding portions with small inner portions and large outer portions, the middle portion is a middle portion with the same inner diameter, and the middle portion of the central hole is located in the middle of a round wire conductor drawing die.
The inner wall of the central hole is provided with symmetrical triangular bulges which are a pair of convex strip-shaped structures distributed in the radial direction, and the triangular bulges extend along the generatrix direction of the conical flaring part and continue to extend in the middle part.
The diameter of the middle part is 1.01D-1.03D, the taper of the outward expansion part is 20-30 degrees, and D is the outer diameter of the REBCO round wire conductor.
The height of the triangular projection is 0.1D-0.15D.
The D is 1.5-9 mm.
Compared with the prior art, the invention has the following remarkable effects:
1) the REBCO round wire conductor with high mechanical strength and high current density is prepared by applying a heating drawing technology to a packaging strengthening process of the REBCO round wire conductor, drawing symmetrical grooves on the surface of the REBCO round wire conductor through a reasonably designed drawing die, penetrating a metal pipe and drawing.
2) The grooves are formed in the surface of the REBCO round wire conductor, so that the extrusion stress in the drawing process of the packaging metal pipe is fully absorbed, and the condition that the structure of a superconducting layer is damaged by an excessive extrusion stress of an REBCO strip is avoided, and the superconductivity is lost.
3) By drawing the triangular groove on the surface of the REBCO round wire conductor, the extrusion stress in the drawing process of the packaging metal pipe can be fully absorbed, and the condition that the structure of a superconducting layer is damaged by an REBCO strip in the conductor due to too large extrusion stress is avoided, so that the superconductivity is lost.
4) The formation of the triangular groove can more easily control the direction of extrusion stress applied to the REBCO strip in the drawing process, and the strip is prevented from delaminating due to excessive shear stress, so that the superconductivity is lost. Meanwhile, residual gap positions can be formed on the outer surface of the round wire conductor after the conductor is pulled out, the anisotropic defect of transverse compression resistance of the conductor is reduced, and the mechanical performance of the conductor is improved.
5) The metal pipe is heated in the drawing process, the temperature is controlled, two-pass drawing is carried out, the diameter reduction ratio of the metal pipe is controlled by using the die, and the superconductivity of the REBCO strip in the drawing forming process can be effectively guaranteed not to be damaged.
6) The method has simple process and high preparation efficiency, the prepared REBCO round wire conductor is not limited in length, and the REBCO round wire conductor can be prepared in a large scale at low cost.
7) The conductor is densely filled, the position of a residual gap is controllable, the thickness of a packaging metal tube can be freely selected, and the mechanical strength is far higher than that of the REBCO round wire conductor prepared by the processes of wrapping, pressing, welding and the like.
Drawings
FIG. 1 is a schematic view of a REBCO round wire conductor before encapsulation;
FIG. 2 is a schematic view of a U-shaped structure for processing a metal pipe;
FIG. 3a is a schematic view of a drawing die for a round wire conductor;
FIG. 3b is a cross-sectional view of a round wire conductor drawing die;
FIG. 3c is a schematic view of a triangular trench;
FIG. 4a is a schematic view of a first pass drawing die;
FIG. 4b is a cross-sectional view of the first pass drawing die;
FIG. 5a is a schematic view of a second pass drawing die;
FIG. 5b is a cross-sectional view of the second pass drawing die;
FIG. 6 is a schematic diagram of a REBCO round wire conductor after package reinforcement;
in the figure: REBCO round wire conductor; 2. a metal tube; 2-1. U-shaped structure; 2-2 incision plane; 2-3, cutting the bottom; 3. drawing the round wire conductor; 3-1, drawing the central hole of the die by the round wire conductor; 3-2. triangular bulge; 3-1-1. the external expansion part of the central hole of the round wire conductor drawing die; 3-1-2, drawing the middle part of the central hole of the die by the round wire conductor; 4-1, drawing the central hole of the die for the first time; 4-1-1, drawing the external expanding part of the die for the first time; 4-1-2, drawing the middle part of the die for the first time; 5-1, drawing the central hole of the die in the second pass; 5-1-1, drawing the external expansion part of the die in the second pass; 5-1-2, drawing the middle part of the die in the second pass; 6. and packaging the reinforced REBCO round wire conductor.
Detailed Description
The invention is further illustrated by the accompanying drawings and the detailed description.
The method aims at the REBCO round wire conductor 1 with the outer diameter D, which is formed by the REBCO strip material 1-1 and metal coated outside the REBCO strip material, and aims to strengthen the packaging of the REBCO round wire conductor. The packaging process is as follows:
1. material preparation
1.1 cleaning REBCO round wire conductor 1
Removing oil stains and an oxidation film on the surface of the REBCO round wire conductor 1 by using 1200-mesh sand paper, cleaning by using alcohol, and blowing to dry at normal temperature for later use, wherein the diameter D of the REBCO round wire conductor is 1.5-9 mm.
As shown in FIG. 1, the REBCO round wire conductor 1 of the present embodiment is packaged with REBCO tape 1-1, the diameter D of the REBCO round wire conductor 1 is 3.2mm, and the cladding material is lead-tin alloy Sn63Pb37
1.2 preparing a metal tube 2 and processing its end into a U-shaped configuration
A metal pipe 2 having an inner diameter of 1.1D to 1.3D and a wall thickness of 0.05D to 0.2D and having smooth inner and outer walls is prepared.
And cutting off two opposite sides of one end of the metal pipe 2 along the direction of the pipe wall to form four cut planes 2-2 and two cut bottoms 2-3, wherein the two cut planes on one side are on the same plane, the cut thickness (the distance between the plane where the two cut planes on one side are located and the pipe wall surface on the side) is 0.12-0.34D, and the cut length (the distance from the end part of the metal pipe 2 to the cut bottoms 2-3) is 18D-50D. This forms a U-shaped structure 2-1 at the end of the metal tube 2, as shown in fig. 2.
The U-shaped structure 2-1 is used for facilitating the penetration of the REBCO round wire conductor 1 and then the penetration of the REBCO round wire conductor through a drawing die as a drawing initial end.
The metal pipe 2 is typically made of red copper, copper alloy, aluminum, or aluminum alloy.
The metal tube 2 used in this example was T1 copper, with an inner diameter of 3.6mm, a wall thickness of 0.5mm, smooth inner and outer walls, a cut thickness of 0.8mm, and a cut length of 60 mm.
1.3 cleaning the cut metal tube 2
Cleaning oil stains on the inner and outer surfaces of the cut metal pipe 2 in the step 1.2 by using alcohol, soaking the metal pipe 2 by using a cleaning brightener to remove a surface oxide layer, washing the metal pipe by using clean water after soaking, and blowing the inner and outer walls to be dry for later use by using normal-temperature air.
The method has the advantages that oil stains and oxidation films on the surfaces of the REBCO round wire conductor 1 and the metal pipe 2 are fully removed, the metal pipe 2 and the REBCO round wire conductor 1 are combined in a contact interface, and the heat dissipation efficiency and the mechanical strength of the packaged conductor can be improved.
In this example, 916 copper cleaning brightener is selected as the cleaning brightener, and the soaking time is 20-120 s.
2. Processing triangular grooves 1-2 outside the REBCO round wire conductor 1
2.1 determining round wire conductor drawing die 3
The drawing die 3 for round wire conductor shown in fig. 3a and fig. 3b has a cylindrical main body, and is provided with a central hole 3-1 along the central axial direction, wherein two ends of the central hole 3-1 are provided with an outer expanding part 3-1-1 with a small inner part and a large outer part, the middle part is provided with a middle part 3-1-2 with a constant inner diameter, and the middle part 3-1-2 of the central hole 3-1 is positioned in the middle part of the drawing die 3 for round wire conductor.
The round wire conductor drawing die 3 is made of hard alloy, the diameter of the middle part 3-1-2 is 1.01D-1.03D, and the taper of the outward expansion part 3-1-1 is 20-30 degrees. The inner wall of the central hole 3-1 is provided with symmetrical triangular bulges 3-2 which are a pair of convex strip-shaped structures distributed in the radial direction, and the convex strip-shaped structures extend along the generatrix direction of the conical shape of the flaring part 3-1-1 and continue in the middle part 3-1-2.
The section of the triangular bulge 3-2 is triangular, the angle is 60 degrees, and the height of the triangular bulge 3-2 is 0.1D-0.15D.
In the embodiment, the diameter of a central hole is 3-1 mm, triangular protrusions 3-2 are symmetrically arranged on the central hole and the conical surface, the angle of the triangular protrusion 3-2 is 60 degrees, and the height of the triangular protrusion 3-2 is 0.4 mm.
2.2 the REBCO round wire conductor 1 enters from the external expanding part at one end of the central hole 3-1 and passes through the round wire conductor drawing die 3, because the triangular protrusion 3-2 is designed on the drawing die 3, when the REBCO round wire conductor 1 passes through the round wire conductor drawing die 3, the connecting line of the top points of the section triangle of the triangular protrusion 3-2 which keeps the same position is vertical to the surface of the REBCO strip 1-1 of the round wire conductor, symmetrical triangular grooves 1-2 are formed on the surface of the REBCO round wire conductor 1 in the drawing process, and the connecting line of the triangular grooves 1-2 is vertical to the plane of the REBCO strip 1-1, as shown in figure 3 c.
By drawing the triangular groove 1-2 on the surface of the REBCO round wire conductor, the extrusion stress in the drawing process of the packaging metal tube 2 is fully absorbed, and the condition that the structure of a superconducting layer is damaged by the REBCO strip material 1-1 in the conductor due to excessive extrusion stress, so that the superconductivity is lost is avoided.
The formation of the triangular groove 1-2 can easily control the direction of extrusion stress applied to the REBCO strip in the drawing process, and the strip is prevented from delaminating due to excessive shear stress, so that the superconductivity is lost. Meanwhile, residual gap positions can be formed on the outer surface of the round wire conductor 1 after the conductor is pulled out, the defect of transverse compression resistance anisotropy of the conductor is reduced, and the mechanical performance of the conductor is improved.
3. The REBCO round wire conductor 1 is penetrated into the metal pipe 2 and the clamp is installed
3.1, the REBCO round wire conductor 1 with the triangular groove 1-2 drawn out is penetrated into the metal pipe 2, the end part of the REBCO round wire conductor 1 is flush with the end part of the metal pipe 2, and the end part notch plane 2-2 of the metal pipe 2 is vertical to the surface of the REBCO strip 1-1 in the REBCO round wire conductor 1.
3.2 clamping the U-shaped structure 2-1 of the metal pipe 2 by using a clamp, wherein the clamping direction is vertical to the surface of the REBCO strip 1-1 of the REBCO round wire conductor 1, namely clamping the notch plane 2-2 at the end part, so that the purpose of fixing is to ensure that the end part of the metal pipe 2 can bear enough drawing force in the subsequent drawing process, and the structure of the REBCO strip 1-1 at the end part is not damaged.
The clamp is a universal clamping structure in the common process, and is convenient for moving the metal tube 2 in the drawing process.
4. Drawing and forming the metal tube 2 penetrating into the REBCO round wire conductor 1
4.1 making the first drawing die 4
As shown in FIGS. 4a and 4b, the first secondary drawing die 4 is similar to the round conductor drawing die 3 in structure, but the inner surface of the central hole is smooth and made of hard alloy, the taper of the flaring portion 4-1-1 of the central hole 4-1 is 20-30 degrees, and the diameter of the middle portion 4-1-2 is 1.11D-1.42D.
In this example, the taper of the flaring portion 4-1-1 is selected to be 26 degrees, and the diameter of the middle portion 4-1-2 is selected to be 4.25 mm.
4.2 heating the metal pipe 2 fixed in the step 3.2 to 180-250 ℃, and drawing the metal pipe 2 through a central hole 4-1 of the first-pass drawing die 4 at a drawing speed of not more than 0.2 m/s.
In this example, heating to 200 ℃ was selected and the drawing speed was 0.15 m/s.
4.3 making a second pass drawing die 5
As shown in fig. 5a and 5b, the second-pass drawing die 5 has the same structure as the first-pass drawing die 4, and the taper of the flared portion 5-1-1 of the central hole 5-1 of the second-pass drawing die 5 is the same as that of the first-pass drawing die 4, but the diameter of the intermediate portion 5-1-2 of the central hole 5-1 of the second-pass drawing die 5 is smaller than that of the first-pass drawing die 4.
The material is hard alloy, the taper of the second-pass drawing expanding part 5-1-1 is 20-30 degrees, and the diameter of the middle part 5-1-2 is 1.102D-1.405D.
In this embodiment, the taper of the flaring portion 5-1-1 of the central hole 5-1 of the second-pass drawing die 5 is 26 °, and the diameter of the middle portion 5-1-2 is 4.21 mm.
4.4 reheating the metal tube 2 to make the temperature of the metal tube reach 180-250 ℃, and passing through the central hole 5-1 of the second-pass drawing die 5 to draw the metal tube 2 at a drawing speed of not more than 0.1 m/s.
In this example, the metal tube 2 was heated to 200 ℃ at a drawing speed of 0.05 m/s.
And 4.5, naturally cooling the metal pipe 2, cutting off the part of the metal pipe 2 clamped by the clamp and the part of the metal pipe not filled with the REBCO round wire conductor 1 in the drawing process, and finally forming the REBCO round wire conductor 6 after the encapsulation is strengthened, as shown in fig. 6.
Claims (19)
1. A packaging strengthening method of REBCO conductors is characterized by comprising the following steps:
1) material preparation
1.1) cleaning the REBCO round wire conductor (1), wherein the outer diameter of the REBCO round wire conductor is D;
1.2) preparing a metal tube (2) and processing the end part of the metal tube into a U-shaped structure;
cutting off two opposite sides of one end of the metal pipe (2) along the direction of the pipe wall to form four notch planes (2-2) and two notch bottoms (2-3), wherein the two notch planes positioned on one side are positioned on the same plane, and a U-shaped structure (2-1) is formed at the end part of the metal pipe (2);
1.3) cleaning the cut metal tube (2);
2) processing a triangular groove (1-2) outside the REBCO round wire conductor (1)
2.1) drawing die for determining round wire conductor (3)
The round wire conductor drawing die (3) is of a cylindrical structure, a central hole (3-1) is machined along the central axial direction, two ends of the central hole (3-1) are respectively provided with an outer expanding part (3-1-1) with a small inner part and a large outer part, the middle part is provided with a middle part (3-1-2) with a constant inner diameter, and the middle part (3-1-2) of the central hole (3-1) is positioned in the middle part of the round wire conductor drawing die (3); symmetrical triangular bulges (3-2) are arranged in the central hole (3-1);
2.2) the REBCO round wire conductor (1) enters from the outward expansion part at one end of the central hole (3-1), passes through the round wire conductor drawing die (3), and the connecting line of the section vertexes of the triangular bulges (3-2) keeping the same position is vertical to the surface of the REBCO strip (1-1) of the round wire conductor to form a triangular groove (1-2);
3) the REBCO round wire conductor (1) is penetrated into the metal pipe (2) and the clamp is installed
3.1) penetrating the REBCO round wire conductor (1) with the triangular groove (1-2) into the metal pipe (2);
3.2) clamping the U-shaped structure (2-1) of the metal pipe (2) by using a clamp, wherein the clamping direction is vertical to the surface of the REBCO strip (1-1) of the REBCO round wire conductor (1);
4) drawing and forming the metal tube (2) penetrating into the REBCO round wire conductor (1)
The secondary drawing die is formed by two-step drawing, the selected secondary drawing die is a cylindrical structure processed with a central hole, the central hole is provided with an outward-expanding part and a middle part, the middle part is positioned in the cylindrical middle part, the taper of the outward-expanding part of the two-step drawing die is the same, but the diameter of the middle part (5-1-2) of the second-step drawing die is smaller than that of the middle part (4-1-2) of the first-step drawing die; heating the metal tube (2) to 180-250 ℃ before each drawing;
naturally cooling the metal pipe (2), cutting off the part of the metal pipe (2) clamped by the clamp and the part of the metal pipe not filled with the REBCO round wire conductor (1) in the drawing process, and finally forming the REBCO round wire conductor (6) after the encapsulation is strengthened.
2. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: in the step 1.1), the REBCO round wire conductor (1) is composed of a REBCO strip (1-1) and metal coated outside the REBCO strip, and the outer diameter D is 1.5-9 mm.
3. The package strengthening method of REBCO conductors as claimed in claim 2, wherein: the inner diameter of the REBCO round wire conductor (1) is 1.1D-1.3D, the wall thickness is 0.05D-0.2D, and the metal coated outside is lead-tin alloy Sn63Pb37。
4. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: in the step 1.1), 1200-mesh sand paper is adopted to remove oil stains and oxidation films on the surface of the REBCO round wire conductor (1), and then the REBCO round wire conductor is cleaned by alcohol and dried by air at normal temperature for later use.
5. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: in the step 1.2), the cutting thickness is 0.12-0.34D and the cutting length is 18D-50D when the U-shaped structure (2-1) is formed.
6. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: in the step 1.3), oil stains on the inner and outer surfaces of the cut metal pipe (2) in the step 1.2 are cleaned by using alcohol, then the metal pipe (2) is soaked by using a cleaning brightener to remove a surface oxide layer, after the soaking is finished, the metal pipe is washed clean by using clean water, and the inner and outer walls are dried by blowing at normal temperature for later use.
7. The package strengthening method of REBCO conductors as claimed in claim 6, wherein: the cleaning brightener 916 copper cleaning brightener, and the soaking time is 20-120 s.
8. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: the round wire conductor drawing die (3) is made of hard alloy, the diameter of the middle part (3-1-2) is 1.01D-1.03D, and the taper of the outward expansion part (3-1-1) is 20-30 degrees.
9. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: the triangular bulges (3-2) are in a pair of convex strip-shaped structures distributed in the radial direction, extend along the generatrix direction of the cone of the flaring part (3-1-1) and continue to the middle part (3-1-2), the angle of the triangular bulges (3-2) is 60 degrees, and the height of the triangular bulges (3-2) is 0.1D-0.15D.
10. The package strengthening method of REBCO conductors as claimed in claim 9, wherein: the diameter of the central hole (3-1) is 3.25mm, and the height of the triangular bulge (3-2) is 0.4 mm.
11. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: in the step 3.1), the end part of the REBCO round wire conductor (1) is flush with the end part of the metal pipe (2), and the end part notch plane (2-2) of the metal pipe (2) is vertical to the surface of the REBCO strip (1-1) in the REBCO round wire conductor (1).
12. The method for strengthening encapsulation of REBCO conductors according to claim 1, wherein the step 4) is specifically:
4.1) making the first drawing die (4)
The taper of the flaring part (4-1-1) of the first-pass drawing die is 20-30 degrees, and the diameter of the middle part (4-1-2) of the first-pass drawing die is 1.11D-1.42D;
4.2) heating the metal pipe (2) to 180-250 ℃, and passing through a central hole (4-1) of the first-pass drawing die (4) to draw the metal pipe (2) at a drawing speed of not more than 0.2 m/s;
4.3) making a second pass drawing die (5)
The taper of the flaring part (5-1-1) of the second-pass drawing die is 20-30 degrees, and the diameter of the middle part (5-1-2) of the second-pass drawing die is 1.102D-1.405D;
4.4) reheating the metal pipe (2) to enable the temperature of the metal pipe to reach 180-250 ℃, and drawing the metal pipe (2) through the central hole (5-1) of the second-pass drawing die at a drawing speed of not more than 0.1 m/s.
13. The package strengthening method of REBCO conductors as claimed in claim 12, wherein: in the step 4.1), the taper of the flaring part (4-1-1) of the first-pass drawing die is 20-30 degrees, and the diameter of the middle part (4-1-2) of the first-pass drawing die is 4.25 mm; in the step 4.2), the temperature is heated to 180-250 ℃, and the drawing speed is 0.01-0.15 m/s; in the step 4.3), the taper of the outward-expanding part (5-1-1) of the second-pass drawing die is 20-30 degrees, and the diameter of the middle part (5-1-2) of the second-pass drawing die is 1.102D-1.405D mm; in the step 4.4), the metal tube (2) is heated to 200 ℃ and the drawing speed is 0.01-0.05 m/s.
14. The package strengthening method of REBCO conductors as claimed in claim 1, wherein: the metal pipe (2) is made of T1 copper.
15. A drawing die in REBCO conductor encapsulation is characterized in that: the main body of the round wire conductor drawing die is of a cylindrical structure, a central hole (3-1) is machined along the central axial direction, two ends of the central hole (3-1) are provided with outer expanding parts (3-1-1) with small inner parts and large outer parts, the middle part is provided with a middle part (3-1-2) with a constant inner diameter, and the middle part (3-1-2) of the central hole (3-1) is positioned in the middle of the round wire conductor drawing die (3).
16. The drawing die in a REBCO conductor package of claim 15, wherein: the inner wall of the central hole (3-1) is provided with symmetrical triangular bulges (3-2) which are a pair of convex strip-shaped structures distributed in the radial direction, and the convex strip-shaped structures extend along the generatrix direction of the cone of the flaring part (3-1-1) and continue in the middle part (3-1-2).
17. The drawing die in a REBCO conductor package of claim 15, wherein: the diameter of the middle part (3-1-2) is 1.01D-1.03D, the taper of the outward expansion part (3-1-1) is 20-30 degrees, and D is the outer diameter of the REBCO circular wire conductor.
18. The drawing die in a REBCO conductor package of claim 17, wherein: the height of the triangular bulge (3-2) is 0.1D-0.15D.
19. The drawing die in a REBCO conductor package of claim 17, wherein: the D is 1.5-9 mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010960097.6A CN112117051A (en) | 2020-09-14 | 2020-09-14 | Encapsulation strengthening method of REBCO conductor and drawing die in encapsulation |
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| CN202010960097.6A CN112117051A (en) | 2020-09-14 | 2020-09-14 | Encapsulation strengthening method of REBCO conductor and drawing die in encapsulation |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114373581A (en) * | 2022-01-14 | 2022-04-19 | 中国科学院电工研究所 | Drawing die, superconducting strip and preparation method thereof |
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