A short process for the production of superconducting wire

Abstract

The application relates to a short-process preparation method of a superconducting wire, which comprises the following steps: preparing an alloy rod and an oxygen-free copper ingot, drilling a plurality of accommodation holes on the oxygen-free copper ingot through a deep drilling process to obtain a porous copper ingot; assembling the alloy rod into the accommodation holes of the porous copper ingot, and welding a cover plate at the opening of the accommodation holes to obtain a composite copper ingot; performing forward extrusion on the composite copper ingot to obtain a composite copper rod; and repeatedly performing stretching and annealing treatment on the composite copper rod to obtain a superconducting wire with a core wire diameter of 30-100 mu m. The NbTi alloy rod is directly inserted into the porous copper ingot, and the finished superconducting wire with a diameter of 0.3-1.0 mm can be prepared through one-time cleaning, assembling, sealing, extrusion and multiple times of drawing and 3-6 times of annealing processes, and finally, the superconducting wire is subjected to insulating processes such as painting, weaving and wrapping, so that the process cycle is greatly shortened, the production line investment is reduced, and the quality risk is lowered; meanwhile, the production and storage costs of the wire supplier are reduced, and the production demand of small batches and multiple specifications of superconducting wires can be met.

Description

Technical Field

[0001] This invention relates to the field of low-temperature superconducting materials technology, and in particular to a short-process preparation method for superconducting wires. Background Technology

[0002] Since its discovery of superconductivity, NbTi alloy has been a mainstay of industrial superconducting wires. Although research and development of its alternative materials, such as high-temperature superconductors, have been rapid, NbTi superconductors remain the preferred choice for practical applications and are widely used in MRI, NMR, particle accelerators, silicon magnets, and nuclear fusion magnets. As these magnets become more sophisticated, the requirements for the stability of superconducting wires and the critical current per unit area of ​​superconductors are also increasing.

[0003] Traditional technologies require processes such as cleaning, assembly, welding, extrusion, and drawing from the manufacturing of subcomponents and finished products. These processes involve large production line investments, long processing times, high quality risks, and complex quality control. Furthermore, current superconducting wires are mainly customized by customers, characterized by small batches and numerous specifications. Wire suppliers using traditional technologies need to manufacture tens of thousands of meters of superconducting wire of a single specification to be economically viable, forcing manufacturers to maintain large inventories of wires and significantly increasing production costs.

[0004] Based on the above-mentioned technical problems, this application proposes a short-process preparation method for superconducting wires. Summary of the Invention

[0005] The purpose of this invention is to provide a short-process method for preparing superconducting wires to solve the technical problems mentioned in the background art. This purpose is achieved through the following technical solutions: A short-process method for preparing superconducting wires includes the following steps: Step S1: Prepare alloy rods and oxygen-free copper ingots. Drill several accommodating holes in the oxygen-free copper ingots using a deep drilling process to obtain porous copper ingots. Clean and dry the alloy rods and porous copper ingots. Step S2: Assemble the alloy rod into the receiving hole of the porous copper ingot, and weld a cover plate at the opening of the receiving hole to obtain a composite copper ingot; the cover plate has an exhaust hole. Step S3: Forward extrusion of the composite copper ingot to obtain composite copper rod; extrusion temperature is 450±20℃-650±20℃, extrusion speed is 7-10mm / s, extrusion ratio is 6-10, and extrusion die angle is 60-150°. Step S4: Repeatedly stretch and anneal the composite copper rod to obtain a superconducting wire with a core wire diameter of 30-100µm; the stretching pass rate is 10-30%, the angle of the stretching die is 4-18°; the annealing temperature is 350±5℃-430±5℃, and the single annealing time is 20-60h.

[0006] Furthermore, the preparation method of oxygen-free copper ingot in step S1 includes: Step S11: Forge oxygen-free copper ingots with an RRR value greater than 250 to obtain oxygen-free copper billets with a grain size of 45-150µm. Step S12: The oxygen-free copper billet is precision-machined to obtain a cylindrical oxygen-free copper ingot; Step S13: Drill 16-55 receiving holes along the axial direction of the oxygen-free copper ingot. The receiving holes are distributed around the axial direction of the oxygen-free copper ingot. The ratio of the hole spacing to the hole diameter is 0.1-0.4. When the number of receiving holes around the ingot is greater than 1, the adjacent receiving holes are arranged in an equilateral triangle. The distance from the edge of the outermost receiving hole to the edge of the oxygen-free copper ingot is 0.1-0.15 of the diameter of the oxygen-free copper ingot.

[0007] Furthermore, the receiving hole is a through hole or a countersunk hole, the diameter deviation of the receiving hole is ±0.2mm, the eccentricity of the receiving hole is ±1mm, the straightness of the receiving hole is ±0.2 / 1000mm, and the surface finish of the inner hole of the receiving hole is Ra0.5.

[0008] Furthermore, step S2 specifically includes: Step S21: Place the assembled porous copper ingot into the vacuum electron beam welding chamber and evacuate to 5×10⁻⁶. -3 Pa, hold pressure for 30 minutes; Step S22: Scan and heat the porous copper ingot with an electron beam. The scanning and heating temperature is less than 100℃ and the scanning and heating time is 5-10 min. Step S23: Fill the vacuum electron beam welding chamber with argon gas to 5-10 kPa, and then evacuate again to 5 × 10 kPa. -3 Pa, the cover plate is subjected to rotary welding; wherein, the electron beam current is 50-100mA, the rotation speed is 100°-300° / min; the weld depth is 5-10mm, and the weld width is 3-5mm.

[0009] Furthermore, step S4 specifically includes: Step S41: After the composite copper rod obtained in step S3 is straightened by straightening, 0.5-1mm of the single-sided outer skin is removed evenly, and then straightened to obtain a composite wire with a diameter of 20-30mm. Step S42: Curl the composite wire with a curling radius of 1500-3000 mm, and then anneal the curled composite wire. Step S43: Perform multiple stretching passes and 2-5 intermediate annealing processes on the annealed composite wire to obtain the final dimensions.

[0010] Furthermore, it also includes: Step S5: Strand the superconducting wire obtained in step S4 with a stranding pitch of 15-100 mm; stretch the stranded superconducting wire with a total elongation of less than 10%.

[0011] Step S6: Wrap an insulating layer around the outside of the superconducting wire obtained in step S5 and perform sintering treatment to obtain the finished superconducting wire.

[0012] Furthermore, the insulation layer is made of adhesive-free PI tape, the wrapping overlap rate of the insulation layer is 5-50%, the dimensional accuracy of the finished superconducting wire is within ±10µm, the withstand voltage rating of the insulation layer is 7-10KV, the width of the adhesive-free PI tape is 5-35mm, and the thickness of the adhesive-free PI tape is 12.5-50µm.

[0013] Furthermore, the alloy rod is a superconducting NbTi alloy rod.

[0014] The technical solutions provided in this application have at least the following technical effects or advantages: 1. By directly inserting NbTi alloy rods into porous copper ingots, finished superconducting wires as thin as 0.3-1.0mm can be produced through a single cleaning, assembly, sealing, extrusion, and 3-4 drawing and annealing processes. This greatly shortens the process cycle, reduces production line investment, and lowers quality risks. At the same time, it reduces the production and inventory costs of wire suppliers and enables the production of small batches of multi-specification superconducting wires. 2. The prepared superconducting wire has a copper-to-superconducting ratio between 1.2 and 7:1, a critical current density of Jc > 2600A@5T, an RRR value > 80, an n value > 40, and can be successfully excited on instrument magnets with capacities of 5T-9T. 3. By drilling the receiving hole in the countersunk hole structure, the preparation and welding time of a cover plate can be reduced, further reducing processing time and processing costs. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0016] Figure 1 This is a schematic diagram showing the location of the receiving hole in an embodiment of this application.

[0017] The attached diagram shows: 1. Oxygen-free copper ingot; 2. Receiving hole. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] Furthermore, a short-process method for preparing superconducting wires includes the following steps: Step S1: Prepare NbTi alloy rods and oxygen-free copper ingots. Drill several accommodating holes in the oxygen-free copper ingots using a deep drilling process to obtain porous copper ingots. Clean and dry the NbTi alloy rods and porous copper ingots.

[0020] The NbTi alloy rods have a diameter of 8-30 mm and a length of 350-800 mm. The size and number of NbTi alloy rods are adjusted according to the size of the porous copper ingot based on the copper-to-weight ratio design, allowing the copper-to-weight ratio to be adjusted between 1.2 and 7.0. The oxygen-free copper ingot is a cylinder with an outer diameter of 150-300 mm and a length of 350-800 mm. The size of the accommodating hole is 0.2-0.5 mm larger than the size of the NbTi alloy rod.

[0021] Methods for preparing oxygen-free copper ingots include: Step S11: Forge oxygen-free copper ingots with an RRR value greater than 250 to obtain oxygen-free copper billets with a grain size of 45-150µm.

[0022] The forging process is as follows: First, the oxygen-free copper ingot is heated to 750-830℃ and held for 2 hours. This process is repeated three times with upsetting and drawing, followed by rapid water cooling. The final forging temperature should not be lower than 600℃; otherwise, it must be reheated before forging. Then, the oxygen-free copper ingot is heated again to 300-330℃ and held for 60 minutes before rapid water cooling. The grain size of the core and edges of the oxygen-free copper ingot is checked and found to be between 45-150µm. Ultrasonic non-destructive testing is used to confirm the absence of internal defects such as porosity, sand holes, inclusions, and cracks.

[0023] The standard for oxygen-free copper ingots is C10100, and its RRR must be greater than 250, the larger the better. However, an excessively large RRR value will lead to excessively high processing costs. It is preferable to have an RRR value of around 400.

[0024] Step S12: The tested oxygen-free copper billet is precision-machined to obtain a cover plate and a cylindrical oxygen-free copper ingot. The size of the oxygen-free copper ingot is determined based on the extrusion press configuration, the size of the extrusion barrel, and the effect of the maximum extrusion temperature on the thermal expansion of copper. Considering the coefficient of thermal expansion, the gap between the oxygen-free copper ingot and the extrusion barrel is between 1.0-2.0 mm, and the size of the extrusion pad is 0.5-1.0 mm smaller than the inner diameter of the extrusion barrel.

[0025] Step S13: Drill 16-55 receiving holes along the axial direction of the oxygen-free copper ingot. The diameter deviation of the receiving holes is ±0.2mm, the eccentricity is ±1mm, the straightness is ±0.2 / 1000mm, and the surface finish of the inner hole is Ra0.5. The receiving holes can be through holes or countersunk holes. When the receiving holes are through holes, both ends of the oxygen-free copper ingot need to be fitted with cover plates, and one of the cover plates has a vent hole. When the receiving holes are countersunk holes, a cover plate is fitted at one end of the oxygen-free copper ingot, and this cover plate has a vent hole, and the end of the NbTi rod matches the bottom of the countersunk hole. Drilling vent holes on the cover plate allows for evacuation and degassing during vacuum welding. The diameter of the vent holes is 2mm, and there are four vent holes. After welding, the vent holes are simultaneously sealed.

[0026] The receiving holes 2 are distributed around the axis of the oxygen-free copper ingot 1, and the ratio of the hole spacing to the hole diameter of the receiving holes 2 is 0.1-0.4; for example... Figure 1 As shown, when the number of turns of the receiving hole 2 is greater than 1 turn, the adjacent receiving holes 2 are distributed in an equilateral triangle. The distance between the edge of the outermost receiving hole 2 and the edge of the oxygen-free copper ingot 1 is 0.1-0.15 of the diameter of the oxygen-free copper ingot 1, so as to ensure that there is a sufficient protective layer in subsequent processing.

[0027] To prevent the waste of expensive oxygen-free copper due to deviations in deep hole drilling, strict deep hole machining processes must be adopted: including accurately inputting parameters on the CNC machining center according to the design drawings, using low feed rate and rapid tool holder rotation; preparing a gun drill specifically for deep holes in advance; conducting trial drilling and diameter measurement before drilling, and ensuring process control and measurement monitoring; using a water-based emulsion with good heat dissipation and lubrication performance, such as Fuchs MCU20, with a concentration of 15-20%; the lubricant needs to be filtered through a precision filter and a magnetic powder filter to ensure no iron powder residue, with a filter accuracy of 20-50µm; and using high-pressure internal and external spraying methods for chip removal and cooling.

[0028] After completing the deep drilling operation, the porous copper ingot is cleaned to remove burrs, and then a coordinate measuring machine is used for inspection.

[0029] The cleaning process specifically includes: For degreasing, use a 30kHz ultrasonic cleaner with a bubble blowing function. Vertical washing is preferred. Maintain a cleaning temperature of 50-60℃ and a cleaning time of 30 minutes. Use a dedicated alkaline degreasing agent diluted with purified water at a concentration of 5%-10%. After degreasing, rinse twice with purified water, blow away any moisture from the pores with compressed air, and then bake in an oven for 30 minutes at a temperature between 50-80℃. The oven needs to be ventilated.

[0030] Polishing involves manually polishing the degreased porous copper ingot to remove tool marks and any remaining trace impurities such as fine iron powder from the inner pores. The polishing material must be an organic material such as a scouring pad. Finally, the ingot is wiped clean with compressed air and anhydrous alcohol, and then vacuum-sealed for the next process.

[0031] Pickling involves soaking the surface in a chemical cleaning agent to remove surface oxides and oil stains from micropores. The chemical cleaning agent contains 5% sulfuric acid, 20-30% hydrogen peroxide, 5% polyethylene glycol, 8% anhydrous ethanol, 8-12% composite stabilizer, and the remainder is purified water. The pickling temperature is controlled at 40-60℃, and the cleaning time is 5-10 minutes. A second rinsing is performed after pickling.

[0032] Passivation is performed using a copper passivating agent containing 30-35% anhydrous ethanol, 10-20% mercaptoimidazole derivative, 2-5% polyethylene glycol, 5-10% benzoic acid, and the remainder being purified water. After passivation, a second rinse with purified water is conducted, and the water droplets are blown away with compressed air. Immediately afterwards, anhydrous alcohol is sprayed, ensuring thorough coverage of the refractory orifice. Finally, rapid drying and vacuum packaging are carried out. The baking oven is a sealed oven, with the temperature controlled at 60-70℃, and the baking time is 2 hours. Vacuum packaging is then performed in a Class 100 cleanroom. The lid undergoes the same cleaning procedure.

[0033] Cleaning is required for NbTi alloy rods. If the supplier was requested to perform pickling and vacuum packaging at the time of purchase, pickling is not necessary.

[0034] Step S2: Assemble the NbTi alloy rod into the receiving hole of the porous copper ingot, and weld a cover plate at the opening of the receiving hole to obtain a composite copper ingot. The cover plate is conical with a taper of 60-150 degrees.

[0035] Assembly must be carried out in a clean room. Specialized tooling must be prepared before assembly to position each component and prevent loosening before transporting it to the vacuum electron beam welding chamber. Assembly personnel must wear cleanroom suits and lint-free gloves. The porous copper ingot is lifted from the packaging bag, the NbTi alloy rod surface is wiped with anhydrous alcohol, and then inserted into the respective receiving holes. Finally, the cover plate is placed on top and clamped together. The weld seams to be welded are temporarily sealed with non-adhesive 3M tape to prevent moisture from entering before welding.

[0036] The welding process specifically includes: Step S21: Place the assembled porous copper ingot into the vacuum electron beam welding chamber, remove the 3M tape, and evacuate to 5×10⁻⁶. -3 Pa, hold pressure for 30 minutes; Step S22: Scan the porous copper ingot with an electron beam to thoroughly remove the moisture inside the oxygen-free copper ingot. The scanning heating temperature is less than 100℃ and the scanning heating time is 5-10 minutes. The heating amount is calculated based on the electron beam current and the heat absorbed by the copper ingot.

[0037] Step S23: Fill the vacuum electron beam welding chamber with argon gas to 5-10 kPa, and then evacuate again to 5 × 10 kPa. -3 The cover plate is subjected to rotary welding at a current of 50-100 mA and a rotation speed of 100°-300° / min. The weld depth is 5-10 mm and the weld width is 3-5 mm. Welding quality is monitored by CCTV during welding, and the weld is inspected using non-destructive testing after welding.

[0038] Step S3: Perform low-speed constant-pressure forward extrusion on the composite copper ingot to obtain a composite copper rod; the extrusion temperature is 450±20℃-650±20℃, the extrusion speed is 7-10mm / s, the extrusion ratio is 6-10, and the extrusion die angle is 60-150°.

[0039] Before extrusion, the composite copper ingot is heated to the target extrusion temperature in a resistance furnace and held at that temperature for 2-4 hours. Simultaneously, the extrusion barrel and extrusion die are heated to 300-350℃. Before extrusion, graphite flakes are pulverized and thoroughly mixed with paraffin oil in a 1:1 ratio, then applied to the sides of the extrusion barrel and the extrusion die. Extrusion is then performed using water quenching for cooling. Using forward extrusion allows the tail of the composite copper ingot to be pushed out through the mandrel, avoiding the need to cut off the tail during reverse extrusion and thus preventing damage to the cutting blades.

[0040] Step S4: Repeatedly stretch and anneal the composite copper rod to obtain a superconducting wire with a core wire diameter of 30-100µm; the stretching pass rate is 10-30%, the angle of the stretching die is 4-18°; the annealing temperature is 350±5℃-430±5℃, and the single annealing time is 20-60h.

[0041] The stretching process specifically includes: Step S41: After the composite copper rod obtained in step S3 is straightened by straightening, 0.5-1mm of the single-sided skin is removed evenly, and the composite wire with a diameter of 20-30mm is obtained by straight drawing. The skin removal method is to use a milling machine and a peeling die to remove the oil and oxide scale caused by extrusion on the surface.

[0042] Step S42: The composite wire is coiled using traditional straight drawing and coil drawing methods, with a coiling radius of 1500-3000 mm. The coiled composite wire is then sent to a bell-type annealing furnace for annealing. The purpose of annealing is to form a superconducting phase in the composite wire and to eliminate material hardening during processing, which is beneficial for subsequent intermediate and fine drawing.

[0043] Step S43: Perform multiple stretching passes and 2-5 intermediate annealing processes on the annealed composite wire to obtain the final dimensions.

[0044] The final size is achieved through conventional methods of disc drawing and multi-die drawing. Small-angle dies are primarily used during drawing to ensure excellent lubrication. The throughput per pass is controlled between 10-30%. All drawing dies are small-angle reducing dies, with angles ranging from 4-18°. Imported emulsion is used as the drawing lubricant, with a concentration between 5-15% and a temperature controlled between 25-45℃. The lubricant requires a circulating filtration function. The minimum final size is 0.3±0.005mm. Step S5: Strand the superconducting wire obtained in step S4 with a stranding pitch of 15-100mm; perform one to two single-stretches on the stranded superconducting wire, with a total elongation of less than 10%.

[0045] Step S6: Wrap an insulating layer around the outside of the superconducting wire obtained in step S5 and sinter it to obtain the finished superconducting wire. The insulating layer is a non-adhesive PI tape, the wrapping overlap rate of the insulating layer is 5-50%, the dimensional accuracy of the finished superconducting wire is within ±10µm, the withstand voltage rating of the insulating layer is 7-10KV, the width of the non-adhesive PI tape is 5-35mm, and the thickness of the non-adhesive PI tape is 12.5-50µm.

[0046] Example 1 Receptacle holes were drilled in an oxygen-free copper ingot with a diameter of 185 mm and a length of 500 mm. The RRR value of the oxygen-free copper ingot was >350. Sixteen receptacle holes were evenly distributed in a ring. The diameter of the receptacle holes was DN19.2 mm ± 0.15 mm, the straightness of the receptacle holes was ± 0.2 mm / 1000 mm, and the hole spacing was 4 mm. Purchased NbTi alloy rods with dimensions of 19 mm ± 0.16 mm were used. After cleaning and assembly, forward extrusion at 500℃ with an extrusion angle of 60 degrees and a stretch elongation controlled below 25% per pass, the ingots underwent four intermediate annealing cycles for a total duration of 120 hours. The copper-to-weight ratio was 4 ± 0.05, the final finished product dimensions were 0.85 mm ± 0.010 mm, and the strand pitch was 59 mm. The measured Jc@5T was 2620A, n value > 40, RRR value > 140, and the average superconducting wire diameter was 92µm, with Cpk > 1.33.

[0047] Example 2 Receptacle holes were drilled in an oxygen-free copper ingot with a diameter of DN185mm and a length of 500mm. The RRR value of the oxygen-free copper ingot was >400. Twenty-seven receptacle holes were evenly distributed in a ring. The diameter of each receptacle was DN13.2mm ± 0.15mm, the straightness of each receptacle was ± 0.2mm / 1000mm, and the hole spacing was 4mm. Purchased NbTi alloy rods with dimensions of 13mm ± 0.16mm were used. After cleaning and assembly, the rods underwent 500-degree forward extrusion at a 90-degree angle. The elongation at break was controlled below 25%. The rods were then subjected to four intermediate annealing cycles for a total duration of 140 hours. The resulting copper-to-weight ratio was 5.5 ± 0.05, and the final finished product dimensions were 1.04mm ± 0.010mm with a strand pitch of 50mm. The measured Jc@5T was 3010A, n value > 40, RRR value > 150, the average superconducting wire diameter was 77µm, and Cpk > 1.67.

[0048] Example 3 Receptacle holes were drilled in an oxygen-free copper ingot with a diameter of DN185mm and a length of 500mm. The RRR value of the oxygen-free copper ingot was >400. Twenty-one receptacle holes were evenly distributed in a ring, with a diameter of DN25.5mm ± 0.20mm, a straightness of ±0.2mm / 1000mm, and a hole spacing of 3.5mm. Purchased NbTi alloy rods with dimensions of 25mm ± 0.16mm were used. After cleaning and assembly, the rods underwent 500-degree forward extrusion at a 120-degree angle. The elongation at break was controlled below 25%. Four intermediate annealing cycles were performed for a total duration of 140 hours. The resulting copper-to-weight ratio was 1.35 ± 0.05, and the final finished product dimensions were 0.600mm ± 0.005mm with a strand pitch of 40mm. The measured Jc@5T was 2880A, n value > 40, RRR value > 160, the average superconducting wire diameter was 82µm, and Cpk > 1.55.

[0049] The technical solutions provided in this application have at least the following technical effects or advantages: 1. By directly inserting NbTi alloy rods into porous copper ingots, finished superconducting wires as thin as 0.3-1.0mm can be produced through a single cleaning, assembly, sealing, extrusion, multiple drawing, and 3-6 annealing processes. This greatly shortens the process cycle, reduces production line investment, and lowers quality risks. At the same time, it reduces the production and inventory costs for wire customers and enables the production of small batches of multi-specification superconducting wires. 2. The prepared superconducting wire has a copper-to-superconducting ratio between 1.2 and 7:1, Jc (critical current density) > 2600A@5T, RRR value > 80, n value > 40, and can be successfully excited on instrument magnets with a capacity of 5T-9T. 3. By drilling the receiving hole in the countersunk hole structure, the preparation and welding time of a cover plate can be reduced, further reducing processing time and processing costs.

[0050] 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.

[0051] 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.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A short-process preparation method for superconducting wires, characterized in that, Includes the following steps: Step S1: Prepare alloy rods and oxygen-free copper ingots. Drill several accommodating holes in the oxygen-free copper ingots using a deep drilling process to obtain porous copper ingots. Clean and dry the alloy rods and the porous copper ingots. Step S2: Assemble the alloy rod into the receiving hole of the porous copper ingot, and weld a cover plate at the opening of the receiving hole to obtain a composite copper ingot; the cover plate has air holes. Step S3: The composite copper ingot is subjected to forward extrusion to obtain a composite copper rod; the extrusion temperature is 450±20℃-650±20℃, the extrusion speed is 7-10mm / s, the extrusion ratio is 6-10, and the extrusion die angle is 60-150°. Step S4: Repeatedly stretch and anneal the composite copper rod to obtain a superconducting wire with a core wire diameter of 30-100µm; the stretching pass rate is 10-30%, the angle of the stretching die is 4-18°; the annealing temperature is 350±5℃-430±5℃, and the single annealing time is 20-60h.

2. The short-process preparation method for superconducting wires according to claim 1, characterized in that, The method for preparing oxygen-free copper ingots in step S1 includes: Step S11: Forge oxygen-free copper ingots with an RRR value greater than 250 to obtain oxygen-free copper billets with a grain size of 45-150µm. Step S12: The oxygen-free copper billet is precision-machined to obtain a cylindrical oxygen-free copper ingot; Step S13: Drill 16-55 receiving holes along the axial direction of the oxygen-free copper ingot. The receiving holes are distributed around the axial direction of the oxygen-free copper ingot. The ratio of the hole spacing to the hole diameter is 0.1-0.

4. When the number of encirclements of the receiving holes is greater than 1, the adjacent receiving holes are arranged in an equilateral triangle. The distance from the edge of the outermost receiving hole to the edge of the oxygen-free copper ingot is 0.1-0.15 of the diameter of the oxygen-free copper ingot.

3. A short-process preparation method for superconducting wires according to claim 1 or 2, characterized in that, The receiving hole is a through hole or a countersunk hole, the diameter deviation of the receiving hole is ±0.2mm, the eccentricity of the receiving hole is ±1mm, the straightness of the receiving hole is ±0.2 / 1000mm, and the surface finish of the inner hole of the receiving hole is Ra0.

5.

4. The short-process preparation method for superconducting wires according to claim 1, characterized in that, Step S2 specifically includes: Step S21: Place the assembled porous copper ingot into the vacuum electron beam welding chamber and evacuate to 5×10⁻⁶. -3 Pa, hold pressure for 30 minutes; Step S22: Scan and heat the porous copper ingot with an electron beam. The scanning and heating temperature is less than 100℃ and the scanning and heating time is 5-10 min. Step S23: Fill the vacuum electron beam welding chamber with argon gas to 5-10 kPa, and then evacuate it again to 5 × 10 kPa. -3 Pa, and then the cover plate is rotary welded; wherein, the electron beam current is 50-100mA, the rotation speed is 100°-300° / min; the weld depth is 5-10mm, and the weld width is 3-5mm.

5. The short-process preparation method for superconducting wires according to claim 1, characterized in that, Step S4 specifically includes: Step S41: After straightening the composite copper rod obtained in step S3, straighten it, then uniformly remove 0.5-1mm of the single-sided outer skin, and then straighten it to obtain a composite wire with a diameter of 20-30mm. Step S42: The composite wire is coiled with a coiling radius of 1500-3000 mm, and the coiled composite wire is then annealed. Step S43: Perform multiple stretching passes and 2-5 intermediate annealing processes on the annealed composite wire to obtain the final dimensions.

6. The short-process preparation method for superconducting wires according to claim 1, characterized in that, Also includes: Step S5: Strand the superconducting wire obtained in step S4, with a stranding pitch of 15-100mm; The stranded superconducting wire is stretched, and the total elongation during stretching is less than 10%. Step S6: Wrap an insulating layer around the outside of the superconducting wire obtained in step S5 and perform a sintering process to obtain the finished superconducting wire.

7. The short-process preparation method for superconducting wires according to claim 6, characterized in that, The insulating layer is a non-adhesive PI tape, the wrapping overlap rate of the insulating layer is 5-50%, the dimensional accuracy of the finished superconducting wire is within ±10µm, the withstand voltage rating of the insulating layer is 7-10KV, the width of the non-adhesive PI tape is 5-35mm, and the thickness of the non-adhesive PI tape is 12.5-50µm.

8. The short-process preparation method for superconducting wires according to claim 1, characterized in that, The alloy rod is a superconducting NbTi alloy rod.

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