CN107283041A - A kind of superconducting joint welder based on magnetic pulse forming techniques - Google Patents

Abstract

A superconducting joint welding device based on magnetic pulse forming technology, comprising a magnetic concentrator (1), an upper pressing plate (3), a lower pressing plate (4) and a discharge coil (2). The upper pressing plate (3) and the lower pressing plate (4) are respectively placed on the upper and lower end surfaces of the magnetic concentrator (1), and a skirt extends outwards. The discharge coil (2) is wound in a groove formed by the outer surface of the magnetic concentrator (1), the upper pressing plate (3) and the skirt protruding from the lower pressing plate (4). When welding the superconducting joint, the superconducting joint composed of the copper tube (5), niobium-titanium rod (6) and multiple niobium-titanium superconducting wires (7) is placed in the central hole of the magnetic concentrator (1). The pulsed magnetic field generated by the discharge coil (2) interacts with the eddy current induced on the copper tube (5) to generate a strong electromagnetic pressure, and the electromagnetic pressure pushes the copper tube (5) and multiple niobium-titanium superconducting wires (7 ) and the niobium-titanium rod (6) are tightly crimped together.

Description

A superconducting joint welding device based on magnetic pulse forming technology

technical field

The invention relates to a superconducting joint welding device of a superconducting magnet.

Background technique

With the development and maturity of superconducting technology, the research and application of superconducting magnets, superconducting cables, superconducting current limiters, superconducting transformers and many other new electrical equipment technologies have attracted more and more attention. Practical superconducting magnets have entered the stage of large-scale. Due to the limitation of the length of commercially supplied superconducting wires or the different requirements of superconducting coils on superconducting wire parameters and the needs of superconducting magnet winding process, it is impossible for superconducting magnets to be wound with the same superconducting wire, so the superconducting wire must be passed through a certain Process technology for resistive or superconductive welding. In addition, in application fields such as nuclear magnetic resonance imaging (MRI) and nuclear magnetic resonance spectrometer (NMR), superconducting magnets are required to achieve high magnetic field uniformity and stability, and closed-loop operation of superconducting magnets is required. In closed-loop operation, the superconducting magnet is connected in parallel with the superconducting switch, so that the magnet is disconnected from the external power supply and realizes lossless operation. In this state, superconducting joints are also required to be connected between the superconducting switch and the superconducting magnet. The quality of superconducting joints between superconducting coils will directly affect the stable operation of the superconducting magnet system.

At present, the common superconducting joint welding methods mainly include brazing, cold pressure welding, diffusion welding and fusion welding. Due to the complex physical structure and special material properties of superconducting materials, it is very difficult to ensure that their performance does not change at all at the joint part of the connection. Although a variety of superconducting joint process technologies have been researched, each process has more or less problems and defects. The brazing process has the advantages of simple equipment, easy operation, and low cost; but because the brazing does not completely form a metallurgical bond at the interface, there is an influence of contact resistance, and the resistance of the brazed joint is generally relatively large, which is generally suitable for high-temperature strips. Connection. The cold pressure welding method is simple and easy, the process is simple, the resistance value of the superconducting joint can be made very small, and the heat generated during the cold pressure welding is very small, which has no effect on the superconducting performance, and the mechanical and electrical properties of the joint are relatively stable; but At present, the performance of the cold press welding process is not stable and is generally only used for low-temperature superconducting wires. Diffusion welding connection can achieve a very low joint resistance value, and can effectively avoid performance degradation caused by the process; The acquisition of oxygen environment is still in the research stage, and there are still many problems to be solved. The fusion welding process includes the process of replacing the matrix material, which makes the welded wire part more fully in contact with the solder during the fusion welding process, so that the joint resistance value of the fusion welding process is very small; but the fusion welding process Complicating matters, joint resistance is affected by the critical properties of the solder and is very sensitive to the effects of background magnetic fields.

Contents of the invention

The purpose of the present invention is to overcome the imperfection existing in the existing superconducting joint welding method, and propose a superconducting joint welding device based on magnetic pulse forming technology. The invention uses the electromagnetic pressure generated by the interaction of the pulsed magnetic field and the induced eddy current to make the welded part of the superconducting joint plastically deform. In the process of magnetic pulse welding, the electromagnetic force is evenly distributed in the metal body to be welded. Therefore, compared with other direct pressure welding, the present invention has the characteristics of uniform shape and better metallurgical bonding, and can prepare extremely high resistivity. Low superconducting joints. In addition, the invention has high production efficiency, can realize automation, can accurately control process parameters and processes, and has stable process performance.

The superconducting joint welding device of the present invention includes a magnetic concentrator, an upper pressing plate, a lower pressing plate and a discharge coil. The upper pressing plate and the lower pressing plate are respectively placed on the upper and lower end faces of the magnetic concentrator, and a skirt edge protrudes outward respectively. The discharge coil is wound in the groove formed by the outer surface of the magnetic concentrator, the upper pressing plate and the skirt protruding from the lower pressing plate.

The magnetic concentrator is made of copper material, and is in the shape of a round pie with a wide circumference and a narrow middle, and has a through hole in the center. Both the upper pressing plate and the lower pressing plate are made of epoxy material, and a through hole is opened in the center of the upper pressing plate, and the aperture is equal to the central aperture of the magnetic concentrator. The discharge coil is a single-layer multi-turn solenoid coil, and the inner surface of the discharge coil is closely attached to the outer surface of the magnetic concentrator. The magnetic concentrator, the upper pressing plate, the lower pressing plate and the discharge coil are coaxial.

The superconducting joint to be welded in the present invention is composed of a copper tube, a niobium-titanium rod and a plurality of niobium-titanium superconducting wires. The niobium-titanium rod is placed in the middle of the copper tube, and multiple niobium-titanium superconducting wires are evenly arranged in the gap between the copper tube and the niobium-titanium rod.

When welding the superconducting joint, the superconducting joint is placed in the center hole of the magnetic concentrator, and the pulse power supply is used to supply power to the discharge coil. The pulsed magnetic field generated by the discharge coil converges in the central hole of the magnetic concentrator through the magnetic concentrator, and induces an eddy current on the copper tube, and the eddy current interacts with the magnetic field to generate a uniform radial contraction electromagnetic pressure, which compresses the The copper tube, multiple niobium-titanium superconducting wires and niobium-titanium rods are tightly crimped together.

Description of drawings

Fig. 1 is a schematic diagram of the central section structure of the superconducting joint welding device of the present invention, in the figure: 1 magnetic concentrator, 2 discharge coil, 3 upper pressing plate, 4 lower pressing plate, 5 copper tube, 6 niobium titanium rod, 7 niobium titanium superconductor Silk.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in FIG. 1 , the superconducting joint welding device of the present invention includes a magnetic concentrator 1 , an upper pressing plate 3 , a lower pressing plate 4 and a discharge coil 2 . The upper pressing plate 3 and the lower pressing plate 4 are respectively placed on the upper and lower end surfaces of the magnetic concentrator 1, and a skirt edge protrudes outwards respectively. The discharge coil 2 is wound in a groove formed by the outer surface of the magnetic concentrator 1 , the skirts protruding from the upper pressing plate 3 and the lower pressing plate 4 .

The magnetic concentrator 1 is made of red copper material, and is in the shape of a round pie with a wide circumference and a narrow middle, and has a through hole in the center. Both the upper pressing plate 3 and the lower pressing plate 4 are made of epoxy material, and the center of the upper pressing plate 3 has a through hole whose diameter is equal to that of the central aperture of the magnetic concentrator 1 . The discharge coil 2 is a single-layer multi-turn solenoid coil, the inner surface of the discharge coil 2 is close to the outer surface of the magnetic concentrator 1, and the magnetic concentrator 1, the upper pressing plate 3, the lower pressing plate 4 and the discharging coil 2 are coaxial.

The superconducting joint to be welded in the present invention is composed of a copper tube 5 , a niobium-titanium rod 6 and a plurality of niobium-titanium superconducting wires 7 . The niobium-titanium rod 6 is placed in the middle of the copper tube 5 , and a plurality of niobium-titanium superconducting wires 7 are evenly arranged in the gap between the copper tube 5 and the niobium-titanium rod 6 .

When welding the superconducting joint, the superconducting joint is placed in the central hole of the magnet concentrator 1, and the discharge coil 2 is powered by a pulse power supply. The pulsed magnetic field generated by the discharge coil 2 converges in the central hole of the magnetic concentrator 1 through the magnetic concentrator 1 and induces an eddy current on the copper tube 5. The interaction between the eddy current and the magnetic field generates a uniform radial contraction electromagnetic pressure. The copper tube 5, multiple niobium-titanium superconducting wires 7 and niobium-titanium rods 6 are tightly crimped together.

Claims (4)

1. A superconducting joint welding device based on magnetic pulse forming technology, characterized in that: said superconducting joint welding device comprises a magnetic concentrator (1), an upper pressing plate (3), a lower pressing plate (4) and a discharge coil ( 2); the upper pressing plate (3) and the lower pressing plate (4) are respectively placed on the upper and lower end faces of the magnetic concentrator (1), and a circle of skirts protrudes outward; the discharge coil (2) is wound on the magnetic concentrator (1) ) outer surface, the upper platen (3) and the lower platen (4) in the groove formed by the protruding skirt. 2. The superconducting joint welding device according to claim 1, characterized in that: the magnetic concentrator (1) is made of copper material, and is in the shape of a round cake with a wide circumference and a narrow middle, and a through hole in the center ; The upper pressing plate (3) and the lower pressing plate (4) are all made of epoxy material, and the upper pressing plate (3) center has a through hole, the aperture is equal to the central aperture of the magnetic concentrator (1); the discharge coil (2) is a single-layer multi-turn solenoid coil, and the inner surface of the discharge coil (2) is close to the outer surface of the magnetic concentrator (1); the magnetic concentrator (1), the upper pressing plate (3), the lower pressing plate (4) and The discharge coil (2) is coaxial. 3. according to the described superconducting joint welding device of claim 1, it is characterized in that: the applicable superconducting joint of described superconducting joint welding device is made of red copper tube (5), niobium-titanium bar (6) and many root niobium-titanium Composed of superconducting wires (7); niobium-titanium rods (6) are placed in the middle of a copper tube (5), and multiple niobium-titanium superconducting wires (7) are evenly arranged in the copper tube (5) and niobium-titanium rods (6 ) in the gap between. 4. According to the superconducting joint welding device described in any one of claims 1-3, it is characterized in that: when welding a superconducting joint, the superconducting joint is placed in the central hole of the magnet concentrator (1), and a pulse power supply is used Supply power to the discharge coil (2); the discharge coil (2) generates a pulsed magnetic field that converges in the central hole of the magnetic concentrator (1) and induces an eddy current on the copper tube (5), and the eddy current interacts with the magnetic field , to generate uniform radial shrinkage electromagnetic pressure, and this electromagnetic pressure crimps the copper tube (5), multiple niobium-titanium superconducting wires (7) and niobium-titanium rods (6) together.