CN213988413U

CN213988413U - Drawing die in REBCO conductor encapsulation

Info

Publication number: CN213988413U
Application number: CN202021999803.XU
Authority: CN
Inventors: 左佳欣; 张腾; 李鹏远; 孙林煜; 罗蓉蓉; 孙振超; 陈辉; 赖小强
Original assignee: Southwestern Institute of Physics
Current assignee: Southwestern Institute of Physics
Priority date: 2020-09-14
Filing date: 2020-09-14
Publication date: 2021-08-17
Anticipated expiration: 2030-09-14

Abstract

The utility model belongs to the technical field of the high temperature superconduction, concretely relates to drawing die in encapsulation of REBCO conductor, its main part is cylindrical structure, along central axial processing centre bore, and the both ends of centre bore are the outer portion that expands of big-end-up in interior, and the centre is the unchangeable intermediate part of internal diameter, and the intermediate part of centre bore is arranged in the middle part of circle line 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 convex strip-shaped structures extend along the generatrix direction of the conical flaring part and continue to the middle part. The designed drawing die is used in the packaging strengthening process of the REBCO round wire conductor, symmetrical grooves are firstly drawn on the surface of the REBCO round wire conductor through reasonable design of the drawing die, and then a metal tube is penetrated for drawing forming, so that the REBCO round wire conductor with high mechanical strength and high current density is prepared.

Description

Drawing die in REBCO conductor encapsulation

Technical Field

The utility model belongs to the technical field of the high temperature superconduction, concretely relates to drawing die in encapsulation of REBCO 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 prevents the REBCO strip from being twisted and wound like a traditional cable, so the REBCO strip needs to be wound on a round core rod or stacked to be made into a round wire, 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.

In order to fully absorb the extrusion stress in the drawing process of the packaging metal tube and avoid the condition that the superconducting layer structure is damaged by the REBCO strip due to the excessive extrusion stress, so that the superconducting property is lost, a novel drawing die needs to be designed.

Disclosure of Invention

The utility model aims at providing a drawing die in encapsulation of REBCO conductor draws triangle slot at REBCO circle line conductor surface, can fully absorb the extrusion stress of encapsulation tubular metal resonator drawing in-process, avoids the REBCO strip in the conductor to destroy the superconductive layer structure because of receiving too big extrusion stress to lose superconductivity.

The technical scheme of the utility model as follows:

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.

The utility model discloses an effect as follows: the designed drawing die is used in the packaging strengthening process of the REBCO round wire conductor, symmetrical grooves are firstly drawn on the surface of the REBCO round wire conductor through reasonable design of the drawing die, and then a metal tube is penetrated for drawing forming, so that the REBCO round wire conductor with high mechanical strength and high current density is prepared. 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.

Drawings

FIG. 1 is a schematic view of a round wire conductor drawing die;

FIG. 2 is a cross-sectional view of a round wire conductor drawing die;

FIG. 3 is a schematic view of a triangular trench;

in the figure: REBCO round wire conductor; 1-1.REBCO tape; 1-2. triangular grooves; 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 mould by the round wire conductor.

Detailed Description

The present invention will be further explained with reference to the drawings and the detailed description.

The die is used in the packaging strengthening process of the REBCO round wire conductor 1. The purpose is to process a triangular groove outside the REBCO round wire conductor 1.

The drawing die 3 for the round wire conductor shown in fig. 1 and fig. 2 has a cylindrical main body, 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 drawing die 3 for the 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 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.

The REBCO round wire conductor 1 enters from an outward expansion part at one end of a central hole 3-1 and passes through a round wire conductor drawing die 3, because a triangular protrusion 3-2 is designed on the drawing round wire conductor drawing die 3, when the REBCO round wire conductor 1 passes through the round wire conductor drawing die 3, the connecting line of the vertexes of the triangular cross section of the triangular protrusion 3-2 at the same position is perpendicular to the surface of a 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 perpendicular to the plane of the REBCO strip 1-1, as shown in figure 3.

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.

Claims

1. 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).

2. The drawing die in a REBCO conductor package of claim 1, 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).

3. The drawing die in a REBCO conductor package of claim 1, 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.

4. The drawing die in a REBCO conductor package of claim 2, wherein: the height of the triangular bulge (3-2) is 0.1D-0.15D, and D is the outer diameter of the REBCO round wire conductor.

5. The drawing die in a REBCO conductor package of claim 3, wherein: the D is 1.5-9 mm.