A compact hollow rotating superconducting magnet device co-rotating with a stirling cryocooler

Abstract

The application provides a compact hollow rotating superconducting magnet device of a common rotation of a Stirling refrigerator, comprising a mounting seat, a rotating driving mechanism, a hollow high-temperature superconducting magnet, a refrigerator mounting seat and a Stirling refrigerator. The Stirling refrigerator is synchronously rotated with the superconducting magnet, the cold head of the Stirling refrigerator is inserted into the Dewar and is coupled with the high-temperature superconducting coil through copper cold conduction, the low-temperature helium rotating dynamic sealing structure is cancelled, the rotating superconducting magnet system with the advantages of compact structure, reliable operation and low energy consumption is realized, and the practical needs of industrial applications such as metal induction heating are met.

Description

Technical Field

[0001] This invention relates to the field of high-temperature superconductivity technology, and in particular to a compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with it. Background Technology

[0002] With the rapid development of modern industry, efficient and low-energy heating technologies for metal materials have become one of the key factors restricting the improvement of high-end manufacturing capabilities. Superconducting induction heating technology, which uses a rotating superconducting magnet to generate a strong rotating magnetic field and induce eddy currents in a metal workpiece for heating, has gradually become an important development direction in the field of metal heat treatment due to its unique advantages of high energy efficiency and high uniformity. This technology uses a strong magnetic field generated by a superconducting coil to act on a metal workpiece passing through the center of the magnet, achieving rapid and uniform heating using the principle of electromagnetic induction. Compared with traditional induction heating methods, it can significantly reduce energy consumption, aligning with the modern industrial trend towards green and low-carbon development.

[0003] However, rotating superconducting magnet devices face numerous technical challenges in practical applications. When a superconducting magnet needs to operate at high speeds, providing a stable and reliable cryogenic cooling environment for the rotating superconducting magnet under these high-speed operating conditions becomes the primary challenge.

[0004] In traditional solutions, the cryocooler is typically kept stationary, while a rotary joint transfers cryogenic helium gas to the rotating magnet. However, cryogenic helium is highly prone to leakage when passing through the rotary joint, and the dynamic sealing structure suffers from severe frictional heat generation at high speeds, resulting in extremely low system reliability and high maintenance costs. This significantly hinders the industrial application of rotating superconducting magnet devices.

[0005] Therefore, how to achieve stable operation of the cryogenic system of the rotating superconducting magnet device and eliminate the risks of helium leakage and frictional heating caused by cryogenic dynamic sealing has become a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to propose a compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating together, which aims to solve to some extent the technical problems of rotating superconducting magnet devices in related technologies, such as unreliable low-temperature dynamic sealing, poor dynamic balance performance, large size and serious AC loss.

[0007] To achieve the above objectives, this invention proposes a compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with it, comprising a mounting base, a rotation drive mechanism, a hollow high-temperature superconducting magnet, a refrigerator mounting base, and at least one Stirling refrigerator, characterized in that: The rotary drive mechanism includes a three-phase asynchronous motor, a multi-ribbed belt, and a bearing housing. The three-phase asynchronous motor drives the hollow main shaft inside the bearing housing to rotate through the multi-ribbed belt. The hollow high-temperature superconducting magnet includes a Dewar and a hollow high-temperature superconducting coil built into the Dewar; the Dewar is a hollow cylindrical structure with a large room temperature through hole in the center, through which a metal workpiece can pass axially to complete superconducting induction heating. The refrigeration unit mounting base is fixedly connected to the outer end face of the Dewar and is eccentrically arranged along the outer circumference of the Dewar. The Stirling refrigerator is rigidly sealed and mounted on the refrigerator mounting base, and rotates synchronously with the Dewar; the cold head of the Stirling refrigerator extends into the Dewar and is thermally coupled to the hollow high-temperature superconducting coil.

[0008] Furthermore, the Dewar, the refrigerator mounting base, and the Stirling refrigerator are rigidly connected to form an integral rotating unit, which is driven to rotate synchronously by a three-phase asynchronous motor. There is no relative rotation between the Stirling refrigerator and the Dewar, and all low-temperature sealing interfaces are static seals. Furthermore, multiple Stirling refrigerators are arranged symmetrically at equal angles along the outer circumference of the Dewar.

[0009] Furthermore, the mounting base is a rigid flat plate structure with pre-drilled mounting holes at the four corners of the plate; the top surface of the mounting base serves as a planar assembly reference surface, synchronously supporting the three-phase asynchronous motor, bearing housing, and hollow high-temperature superconducting magnet.

[0010] Furthermore, the three-phase asynchronous motor is rigidly fixed to the eccentric area at the front end of the mounting base, and a drive pulley is provided at the output end; one end of the multi-ribbed belt is sleeved on the output pulley of the three-phase asynchronous motor, and the other end is sleeved on the hollow spindle pulley.

[0011] Furthermore, the bearing housing is vertically fixed in the middle of the mounting base, and a high-precision heavy-duty support bearing is integrated inside; the hollow spindle runs through the bearing housing body, with one end connected to the pulley and the other end rigidly connected to the Dewar.

[0012] Furthermore, the Dewar has a hollow cylindrical structure with a through hole for room temperature; the outer wall end face of the Dewar is provided with a flange structure, and multiple sets of assembly threaded holes are evenly opened on the flange surface for rigidly fixing the refrigeration unit mounting base. Multiple refrigeration units are mounted on mounting bases at equal angles along the Dewar circumference. The eccentric masses of each refrigeration unit cancel each other out during rotation, ensuring the dynamic balance performance of the entire unit.

[0013] Furthermore, the Dewar also contains a copper cooling component, a magnet frame, and a high-temperature superconducting coil. The magnet frame is made of a low thermal conductivity, high strength non-metallic cryogenic material and has a hollow ring structure. The high-temperature superconducting coil is tightly wound and fixed to the outer periphery of the magnet frame. One side of the copper cooling component is tightly pressed against the cold head, while the other side is fitted and wrapped around the high-temperature superconducting coil and the magnet frame.

[0014] Furthermore, the device also includes a conductive slip ring assembly, comprising an outer conductive slip ring and an inner conductive slip ring; the outer conductive slip ring is fixed to an external stationary frame, and the inner conductive slip ring rotates synchronously with the Dewar and the high-temperature superconducting coil; the conductive slip ring assembly is arranged in the ambient temperature region outside the left end of the Dewar and does not extend into the vacuum cryogenic cavity inside the Dewar.

[0015] Furthermore, an independent electromagnetic shielding cylinder is installed on the inner wall of the central room temperature through-hole of the Dewar; the electromagnetic shielding cylinder is kept in a normal temperature environment throughout and does not come into contact with the low-temperature cold mass inside the Dewar.

[0016] Compared with the prior art, the advantages of the present invention are: 1. No cryogenic dynamic seals throughout: Since the Stirling refrigerator and the Dewar rotate synchronously, all cryogenic sealing interfaces are static seals. There is no relative rotation between the refrigerator and the cryogenic Dewar, avoiding the pain points of traditional equipment such as helium leakage, dynamic seal friction and heat generation, and large cold loss, which significantly improves the reliability and service life of the system.

[0017] 2. Dynamically balanced and stable operation: Multiple Stirling refrigerators are arranged symmetrically at equal angles along the outer ring of the magnet. During rotation, the eccentric masses cancel each other out, resulting in strong stability under high-speed rotation conditions and low vibration and noise.

[0018] 3. Low AC loss and low energy consumption: The independent electromagnetic shielding cylinder on the room temperature side does not come into contact with the cryogenic cold mass, which helps to reduce the eddy current heat load on the cryogenic cold mass component. The AC loss of the superconducting coil is greatly reduced, effectively solving the problem of high energy consumption in metal heating.

[0019] 4. Extremely compact space: Within a tiny space with an outer diameter of less than 400mm and an axial length of less than 260mm, a Φ160mm large-diameter workpiece channel is achieved. Two or four chillers can be flexibly connected in parallel, adapting to various metal welding heating, continuous heat treatment, workpiece quenching and other through-type metal heat working conditions, as well as compact high-speed rotating magnetic field equipment for alternating magnetic field material testing, special electromagnetic heat treatment and other applications. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the rotating superconducting heating device of the present invention.

[0021] Figure 2 This is a partially enlarged assembly diagram of the rigid integration of the hollow high-temperature superconducting magnet cryostat and the Stirling refrigerator in this invention.

[0022] Figure 3 This is an internal cross-sectional view obtained by cutting the device of the present invention along the axial direction.

[0023] Reference numerals: 1. Mounting base; 2. Three-phase asynchronous motor; 3. Multi-ribbed belt; 4. Bearing housing; 5. Dewar; 6. Refrigeration unit mounting base; 7. Stirling refrigeration unit; 8. Cold head; 9. Copper heat-conducting component; 10. Magnet frame; 11. High-temperature superconducting coil; 12. Conductive slip ring assembly; 121. Outer ring of conductive slip ring; 122. Inner ring of conductive slip ring; 13. Electromagnetic shielding cylinder. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0025] like Figures 1 to 3 As shown in the figure, a compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the present invention mainly includes a mounting base 1, a three-phase asynchronous motor 2, a multi-wedge belt 3, a bearing housing 4, a hollow high-temperature superconducting magnet, a refrigerator mounting base 6, a Stirling refrigerator 7, a cold head 8, a copper cooling component 9, a magnet frame 10, a high-temperature superconducting coil 11, a conductive slip ring assembly, and a hollow spindle. The entire device is used in the field of metal induction heating. It generates a rotating high-intensity superconducting magnetic field to perform low-energy induction heating on metal workpieces passing through the central hole of the device. It is suitable for induction welding, continuous heat treatment, workpiece quenching, and other through-type metal heat working conditions such as tubular or shaft-like metals. It can also be extended to compact high-speed rotating magnetic field equipment for alternating magnetic field material testing and special electromagnetic heat treatment.

[0026] Mounting base 1 serves as the load-bearing foundation plate component of the entire device. The plate is rectangular and rigid, with standard-sized mounting holes pre-drilled at the four corners for rigidly fixing the entire rotating superconducting magnet device to the metal induction heating station frame using bolts. The top surface of mounting base 1 serves as the planar assembly reference surface, simultaneously supporting the three-phase asynchronous motor 2, bearing housing 4, and high-temperature superconducting magnet assembly during assembly. High-precision machining ensures the coaxiality and assembly rigidity requirements of all rotating components, achieving an integrated rigid structure for the entire rotating unit. Mounting base 1 is made of high-strength metal material with sufficient bending stiffness in the thickness direction. When bearing the weight of the entire rotating assembly and the dynamic loads generated by high-speed rotation, the deformation is controlled within allowable limits, ensuring stable operation of the device under high-speed rotation conditions of 200 to 500 revolutions per minute.

[0027] The three-phase asynchronous motor 2 serves as the rotational drive power source for the entire device. It is rigidly fixed to the eccentric region at the front end of the mounting base 1, an eccentric arrangement that optimizes the overall center of gravity and transmission structure layout. The output end of the three-phase asynchronous motor 2 is equipped with a drive pulley, forming a belt drive pair structure with the hollow main shaft pulley on the bearing housing 4 side via a multi-wedge belt 3. During operation, the motor synchronously drives the hollow high-temperature superconducting magnet and the Stirling refrigerator 7 to rotate as a whole, achieving synchronous rotational motion between the refrigeration unit and the superconducting magnet without relative rotation. The power specifications of the three-phase asynchronous motor 2 are determined based on the overall mass of the device and the target rotational speed, with a typical power range from several kilowatts to tens of kilowatts. Smooth speed adjustment can be achieved via a frequency converter, covering an operating range of 200 to 500 revolutions per minute.

[0028] The multi-wedge belt 3, as a power transmission connection component, adopts a multi-wedge flexible transmission structure design. One end is sleeved on the output pulley of the three-phase asynchronous motor 2, and the other end is sleeved on the hollow main shaft pulley on the side of the bearing housing 4. The structure of the multi-wedge belt 3 has the advantages of smooth torque transmission, buffering rotational vibration, and adapting to eccentric transmission spacing. It can effectively absorb the impact load during motor start-up and braking, reducing the vibration and noise level of the entire rotating unit. The multi-wedge belt 3 is made of a composite structure of low-temperature resistant special rubber and high-strength fiber composite material. It maintains flexibility and transmission reliability under the low-temperature environment generated by the synchronous rotation of the refrigeration unit with the magnet, and its service life meets the requirements of continuous industrial operation.

[0029] The bearing housing 4 is vertically fixed in the middle of the mounting base 1, and integrates a high-precision heavy-duty support bearing assembly. This bearing assembly adopts a combination structure of angular contact ball bearings or tapered roller bearings capable of withstanding bidirectional axial and radial loads. A hollow spindle runs through the central channel of the bearing housing 4. One axial end is fixed to the pulley driven by the multi-wedge belt 3 via a key connection or a shrink sleeve connection, while the other end is rigidly connected to the hollow high-temperature superconducting magnet via a flange. The bearing housing 4 provides stable radial support and axial positioning for the high-speed synchronous rotating assembly consisting of the hollow high-temperature superconducting magnet and the Stirling refrigerator 7, effectively suppressing eccentric vibrations generated during high-speed rotation and ensuring that the overall dynamic balance performance meets design requirements. The bearings inside the bearing housing 4 adopt a lifetime lubrication and sealing structure, resulting in a long maintenance cycle, high reliability, and meeting the requirements for long-term maintenance-free operation in industrial settings.

[0030] The hollow high-temperature superconducting magnet is the core functional component of this device, employing an integrated structure of a hollow large-aperture high-temperature superconducting coil and a cryogenic thermostat. For example... Figure 1 and Figure 2As shown, the hollow high-temperature superconducting magnet is rigidly fixed to the end of the hollow main shaft of the bearing housing 4, and rotates synchronously with the main shaft and the Stirling refrigerator 7. The hollow high-temperature superconducting magnet houses the high-temperature superconducting coil 11 and forms a sealed low-temperature chamber. A 160 mm diameter through-hole at room temperature is provided in the middle of the hollow magnet, allowing the metal workpiece to pass through axially to achieve superconducting induction heating. The outer wall of the thermostat of the hollow high-temperature superconducting magnet is rigidly sealed to the cold head 8 of the Stirling refrigerator 7, eliminating relative rotation between them and completely eliminating the low-temperature helium rotating dynamic sealing structure of traditional technical solutions.

[0031] The Dewar 5 is a sealed cryogenic vacuum chamber housing the high-temperature superconducting coil 11 within a hollow high-temperature superconducting magnet, serving as the core cryogenic load-bearing component of the entire superconducting magnet system. The Dewar 5 adopts a hollow cylindrical structure with a large-sized room-temperature through-hole at its center, allowing metal workpieces to pass through axially for superconducting induction heating. The outer wall of the Dewar 5 features a flange structure with multiple sets of standard-sized threaded holes evenly spaced on the flange surface for rigidly fixing the refrigerator mounting base 6 and its associated Stirling refrigerator 7. The interior of the Dewar 5 forms a high-vacuum, insulated cryogenic chamber, within which the high-temperature superconducting coil 11 is housed. The outer wall of the Dewar 5 is connected to the cold head 8 of the Stirling refrigerator 7 via a sealed flange structure, rigidly forming a single integrated structure. During rotational operation, there is no relative rotational interface between the Dewar 5 and the refrigerator 7, completely eliminating the need for a cryogenic helium rotating dynamic seal structure required in traditional designs. This fundamentally eliminates the risk of helium leakage and the cooling loss caused by dynamic seal friction heating. The Dewar 5 was designed under strict constraints on its extremely small external dimensions, with the overall outer diameter controlled within 400 mm and the axial length controlled within 260 mm. Under such tight space constraints, it successfully achieved the layout of a large-diameter hollow channel with a diameter of 160 mm, maximizing the overall space utilization of the machine.

[0032] The refrigerator mounting base 6 is fixedly connected to the flange position on the outer end face of the Dewar 5, providing rigid positioning and load-bearing support for the Stirling refrigerator 7. The refrigerator mounting base 6 is installed eccentrically along the outer circumference of the Dewar 5. This eccentric arrangement does not occupy the room temperature through-hole space at the center of the Dewar 5, perfectly adapting to the hollow configuration requirements of the hollow magnet structure. The refrigerator mounting base 6 has multiple standardized refrigerator assembly interfaces, allowing for the simultaneous assembly of two Stirling refrigerators 7, or the addition of up to four refrigerator units at equal angles along the circumference of the Dewar 5, enabling a flexible configuration scheme for parallel expansion of multiple refrigerators. When multiple refrigerator mounting bases 6 are arranged at equal angles around the Dewar 5, the eccentric mass of each refrigerator can cancel each other out during rotation, thus ensuring excellent high dynamic balance performance of the entire system. The refrigerator mounting base 6 is rigidly locked to the end face of the Dewar 5 using high-strength bolts, rotating synchronously with the Dewar 5 to ensure that the Stirling refrigerator 7 and the cryogenic chamber remain relatively stationary, eliminating cryogenic sealing friction pairs.

[0033] The Stirling cryostat 7 is rigidly and sealed to the cryostat mounting base 6 via a flange structure. The cold head 8 of the cryostat 7 extends into the vacuum cryogenic chamber of the Dewar 5, forming an effective thermal coupling connection with the internal high-temperature superconducting coil 11, providing a stable cryogenic cooling condition for the superconducting coil. This device can operate in a parallel configuration of two or more Stirling cryostats 7, with the cold heads 8 of multiple cryostats simultaneously supplying cooling capacity to the high-temperature superconducting coil 11 inside the Dewar 5. The total cooling capacity output can be flexibly superimposed according to the cooling requirements of different metal heating conditions. The Stirling cryostat 7 adopts an eccentric external arrangement, completely avoiding the passageway of the central workpiece, allowing for greater freedom in assembly and layout, and facilitating the miniaturization and compact design of the entire system. During operation, the Stirling cryostat 7 rotates synchronously as a whole with the cryostat mounting base 6, the Dewar 5, and the superconducting coil 11. There is no relative rotational motion between the cryostat and the cryogenic Dewar, thus eliminating the need for a rotary cryogenic dynamic sealing structure. In this embodiment, the energized end of the Stirling refrigerator 7 is electrically connected to the conductive slip ring assembly, and wirelessly controlled by the external control system via Hall effect, simplifying the complexity of electrical connections during rotation.

[0034] The cold head 8 is a key component of the cryogenic cooling output end of the Stirling refrigerator 7. One end is connected to the body of the Stirling refrigerator 7 via a metal seal, while the other end is tightly fitted to the copper cooling conductor 9 and extends into the cryogenic vacuum chamber inside the Dewar 5. The cold head 8 rotates synchronously with the refrigerator 7, continuously transferring cooling energy to the copper cooling conductor 9, providing a stable superconducting critical operating temperature range for the high-temperature superconducting coil 11. The cold head 8 and the body of the refrigerator 7 adopt an integrated rotating structure design, eliminating the rotating sealing interface and completely eliminating the technical risk of cryogenic working fluid leakage. The end face of the cold head 8 is precision machined to form a high-quality thermal contact interface with low thermal resistance between it and the copper cooling conductor 9, ensuring that the heat transfer efficiency meets the cooling requirements of the high-temperature superconducting coil 11.

[0035] The copper cooling component 9 is a low-temperature heat transfer component made of high thermal conductivity copper. One side is tightly pressed against the cold head 8 to form a reliable thermal connection with low thermal resistance, while the other side is attached to and covers the outer surface of the high-temperature superconducting coil 11 and the magnet frame 10. The copper cooling component 9 evenly conducts the cooling output from the cold head 8 to the entire range of the superconducting coil 11, possessing excellent temperature uniformity and effectively eliminating local temperature differences in the superconducting coil 11, thus avoiding superconducting quench failure caused by local temperature rise. The copper cooling component 9 is entirely located in the low-temperature cavity region inside the Dewar 5, and only has thermal contact with the cold head 8 and the superconducting coil 11. It is completely thermally isolated from the external ambient temperature structure by the high-vacuum insulation interlayer of the Dewar 5, minimizing the impact of external heat leakage on the low-temperature system. The structural shape of the copper cooling component 9 is customized according to the outer contour of the magnet frame 10, adopting a segmented or integral sleeve structure, and is fixedly connected to the magnet frame 10 by interference fit or screw fastening.

[0036] The magnet skeleton 10 serves as the supporting structure for the high-temperature superconducting coil 11. It is made of a non-metallic cryogenic material with low thermal conductivity and high strength, such as glass fiber reinforced composite material or carbon fiber reinforced composite material. The magnet skeleton 10 adopts a hollow ring structure with a 160 mm diameter room temperature through-hole at the center. The outer circumferential surface of the magnet skeleton 10 is fitted and fixed to the copper cooling component 9, while the internal space is used to wind and fix the high-temperature superconducting coil 11. The hollow structure of the skeleton ensures that the metal workpiece can pass through the center of the magnet in the axial direction to complete the induction heating process; the low thermal conductivity material effectively blocks the conduction loss of cold energy towards the central room temperature hole, reducing cryogenic cold energy loss; at the same time, the skeleton has sufficient structural rigidity and strength to support the coil and copper cooling component without deformation, displacement, or loosening under high-speed rotation conditions. The magnet skeleton 10 and the inner wall of the Dewar 5 are precisely positioned in the circumferential direction through a positioning key or stop structure to ensure the installation position accuracy of the superconducting coil 11 relative to the Dewar 5.

[0037] The high-temperature superconducting coil 11 is the core functional component of this device for achieving superconducting induction heating. It is tightly wound and fixed to the outer periphery of the magnet frame 10, and is externally covered by a copper cooling component 9 to achieve a full-area cryogenic cooling effect. The high-temperature superconducting coil 11 is located inside the sealed vacuum cryogenic chamber of the Dewar 5, and rotates synchronously with the magnet frame 10, the Stirling refrigerator 7, and the Dewar 5. The high-temperature superconducting coil 11 maintains its superconducting critical temperature state by relying on the parallel cooling mode of two Stirling refrigerators 7. After being energized, it generates a high-intensity alternating magnetic field, which enables low-energy eddy current induction heating of metal workpieces passing through the central room-temperature through-hole. The excitation current of the high-temperature superconducting coil 11 is delivered through the external power supply system via the conductive slip ring assembly. The coil's resistance is close to zero in the superconducting state, which can carry large currents and generate strong magnetic fields, showing significant energy efficiency advantages compared to conventional resistance induction heating equipment. The high-temperature superconducting coil 11 is designed with a multi-coil segmented winding or disc winding structure, and is optimized according to the magnetic field distribution requirements and cooling channel arrangement. The coil turns are electrically isolated by a special insulating material for high-temperature superconducting tape to ensure the electrical safety of the coil under strong magnetic field and high current conditions.

[0038] The conductive slip ring assembly comprises two parts: an outer conductive slip ring 121 and an inner conductive slip ring 122. Together, they form the room-temperature rotating conductive slip ring system of the entire device. The conductive slip ring assembly is positioned in the room-temperature region on the outer left side of the Dewar 5, without extending into the internal cryogenic vacuum chamber of the Dewar 5, thus avoiding the introduction of additional heat leakage into the cold mass. The inner conductive slip ring 122 rotates synchronously with the Dewar 5 and the high-temperature superconducting coil 11, while the outer conductive slip ring 121 is fixed to an external stationary frame. The two parts achieve sliding contact through a precious metal brush assembly, establishing an electrical connection between the stationary external excitation power supply and the rotating high-temperature superconducting coil 11, enabling continuous and stable excitation current delivery. The conductive slip ring assembly operates entirely at room temperature, achieving effective thermal isolation from the internal cryogenic vacuum chamber. It does not occupy the radial or axial cryogenic space of the Dewar 5, effectively ensuring the compact design of the internal cryogenic chamber. The conductive slip ring assembly employs a multi-channel design, capable of simultaneously transmitting excitation current, measurement signals, and monitoring data, meeting the comprehensive electrical interface requirements of the superconducting magnet system.

[0039] The hollow spindle has a hollow structure, penetrating the bearing housing 4 body. One end is fixed to the pulley via a key connection or expansion sleeve, and the other end is rigidly fixed to the Dewar 5 via a flange. The central channel of the hollow spindle allows cryogenic pipelines, electrical cables, etc., to pass through, enabling media and signal transmission between the rotating and stationary ends. The hollow spindle is made of high-strength alloy steel and undergoes precise dynamic balancing, keeping vibration levels low even under high-speed rotation conditions.

[0040] An independent electromagnetic shielding cylinder 13 is installed on the inner wall of the central room-temperature through-hole of the Dewar 5. This electromagnetic shielding cylinder 13 operates entirely at room temperature, without thermal contact with the cryogenic cold mass inside the Dewar 5. The electromagnetic shielding cylinder 13 is made of a high-conductivity metal material such as copper or aluminum, and its wall thickness is designed and calculated according to the shielding effectiveness requirements. Without increasing the cryogenic cold mass, the independent electromagnetic shielding cylinder 13 utilizes the eddy current shielding effect of the metal material to cut off the eddy current thermal shock path generated by the alternating magnetic field of the superconducting coil 11 on the cryogenic cold mass component, thereby reducing the AC loss level of the superconducting coil 11 from the source and effectively solving the technical problem of high energy consumption in metal induction heating equipment.

[0041] The workflow of the compact hollow rotating superconducting magnet device with Stirling refrigerator rotating in conjunction with the present invention in practical application is as follows. In the equipment assembly and pre-preparation stage, the entire device is first rigidly locked and fixed to the metal induction heating station frame through the four corner mounting holes of the mounting base 1. Precision measuring tools such as a laser collimator or dial indicator are used to adjust the coaxiality of the three-phase asynchronous motor 2, bearing housing 4, and hollow high-temperature superconducting magnet Dewar 5, ensuring precise alignment of the machine's rotation axis with the workpiece conveying channel. The metal workpiece to be heated and welded is passed axially through a 160mm diameter room temperature through-hole in the center of the hollow high-temperature superconducting magnet. A special fixture is used to complete the workpiece positioning and clamping operation. In other embodiments, the room temperature through-hole should be no less than 160mm to meet the large-size room temperature through-hole requirement of the present invention. The cryogenic chamber inside Dewar 5 is evacuated to a high vacuum level exceeding 10^-3 Pascals, effectively isolating air convection heat leakage. Simultaneously, a helium mass spectrometer leak detector is used to check the static seal connections between the Stirling refrigerator 7, the refrigerator mounting base 6, and the cold head 8, confirming the absence of helium leakage risks. An external static excitation power supply is electrically connected to the outer ring 121 of the conductive slip ring, with the inner ring 122 rotating synchronously with Dewar 5 to form a continuous conductive path. An independent electromagnetic shielding cylinder 13, pre-installed at room temperature, is positioned on the inner wall of the room temperature through-hole of Dewar 5, ensuring the shielding cylinder remains at room temperature and does not contact the cryogenic mass throughout the process. The required total cooling capacity is determined based on the material type, cross-sectional thickness, and target heating temperature of the metal workpiece to be heated, and two Stirling refrigerators 7 are activated in parallel operation. If the workpiece has a large heat load, the number of Stirling refrigerators 7 can be expanded to four along the circumference of Dewar 5 at equal angles, using a symmetrical arrangement to offset eccentric masses and maintain dynamic balance performance.

[0042] During the pre-cooling stage, the two Stirling refrigerators 7 are powered on and started simultaneously. The entire refrigerator unit remains stationary during pre-cooling along with the Dewar 5, with no relative rotation between them. The cold head 8 of the Stirling refrigerator 7 outputs low-temperature cooling energy, which is uniformly conducted to the surface of the high-temperature superconducting coil 11 wound on the magnet frame 10 through the copper cooling conductor 9. The high thermal conductivity copper cooling conductor 9 covers the entire structure of the high-temperature superconducting coil 11, eliminating local temperature differences in the coil and continuously cooling until the temperature of the high-temperature superconducting coil 11 drops below the superconducting critical temperature range. The entire low-temperature sealing interface adopts a static sealing structure, eliminating the dynamic sealing caused by low-temperature helium rotation, and completely eliminating the problem of cooling loss caused by sealing friction heating and helium leakage. The vacuum jacket of the Dewar 5 effectively isolates the radiative heat leakage effect of the external ambient temperature environment. The independent electromagnetic shielding cylinder 13 on the room temperature side is pre-positioned and in working condition, blocking the eddy current thermal shock of the alternating magnetic field to the internal components of the low-temperature cavity, reducing the AC loss of the superconducting coil 11 from the source, and significantly reducing the additional heat load during the pre-cooling stage.

[0043] During the synchronous rotation heating phase, the three-phase asynchronous motor 2 is energized and drives the hollow main shaft inside the bearing housing 4 to rotate via the multi-wedge belt 3. The main shaft drives the Dewar 5, the refrigerator mounting base 6, the Stirling refrigerator 7, the cold head 8, the copper cooling component 9, the magnet frame 10, and the high-temperature superconducting coil 11 to rotate synchronously and uniformly as a whole, with no relative rotation between the refrigeration unit and the superconducting magnet. The Stirling refrigerator 7 rotates synchronously at high speed with the magnet, and the cold head 8 continuously outputs cooling energy to maintain the superconducting operating temperature of the high-temperature superconducting coil 11. Two or four Stirling refrigerators 7 are arranged symmetrically at equal angles around the Dewar 5, canceling out the rotational eccentric loads between them, resulting in excellent dynamic balance performance of the entire machine and significantly reduced vibration and noise levels during high-speed operation. The external excitation power supply slides through the stationary outer ring 121 of the conductive slip ring and the rotating inner ring 122 of the conductive slip ring to stably deliver excitation current to the high-temperature superconducting coil 11 in a high-speed rotating state; the coil 11 carries a large current under low-temperature superconducting conditions, generating a high-intensity alternating magnetic field. A metal workpiece passing through a room-temperature through-hole in the center of the magnet cuts alternating magnetic field lines, achieving low-energy eddy current induction heating through a superconducting strong magnetic field. An induced current is generated inside the metal workpiece and converted into heat, achieving rapid and uniform heating. An independent electromagnetic shielding cylinder 13 on the room-temperature side effectively isolates the risk of eddy current heating on the low-temperature cold mass component from the alternating magnetic field, significantly reducing coil AC losses and overall heating energy consumption compared to conventional induction heating equipment. When workpiece specifications or heating processes change, the total cooling capacity output can be adjusted by increasing or decreasing the number of Stirling refrigerators 7 in operation, matching system heat leakage and heat load under different operating conditions, and ensuring that the high-temperature superconducting coil 11 remains stably in a superconducting operating state.

[0044] In some optional implementations, the number of Stirling chillers 7 can be flexibly configured according to actual cooling capacity requirements. Besides the standard configuration of two or four units, an asymmetric balancing scheme can be adopted, with three chillers arranged at equal angles of 120 degrees around the outer circumference of the Dewar 5. Rotational dynamic balance is achieved through precise calculation of the mass and position of each chiller. The drive control of the three-phase asynchronous motor 2 adopts vector frequency conversion control technology to achieve low-speed, high-torque output and precise closed-loop speed control, meeting the stringent requirements of metal heating processes for rotational speed stability. The brushes of the conductive slip ring assembly are made of silver or gold alloy materials to reduce contact resistance and contact heat loss, improving electrical transmission efficiency and service life.

[0045] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating together, comprising a mounting base (1), a rotation drive mechanism, a hollow high-temperature superconducting magnet, a refrigerator mounting base (6), and at least one Stirling refrigerator (7), characterized in that: The rotary drive mechanism includes a three-phase asynchronous motor (2), a multi-ribbed belt (3), and a bearing housing (4). The three-phase asynchronous motor (2) drives the hollow spindle inside the bearing housing (4) to rotate through the multi-ribbed belt (3). The hollow high-temperature superconducting magnet includes a Dewar (5) and a hollow high-temperature superconducting coil (11) built into the Dewar (5); the Dewar (5) is a hollow cylindrical structure with a large room temperature through hole in the center for the metal workpiece to pass through axially to complete superconducting induction heating; The refrigeration unit mounting base (6) is fixedly connected to the outer end face of the Dewar (5); The Stirling refrigerator (7) is rigidly and sealed on the refrigerator mounting base (6) and rotates synchronously with the Dewar (5); the cold head (8) of the Stirling refrigerator (7) extends into the Dewar (5) and is thermally coupled to the hollow high-temperature superconducting coil (11).

2. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The Dewar (5), the refrigerator mounting base (6), and the Stirling refrigerator (7) are rigidly connected to form an integral rotating unit, which is driven to rotate synchronously by the three-phase asynchronous motor (2). There is no relative rotation between the Stirling refrigerator (7) and the Dewar (5), and all low-temperature sealing interfaces are static seals.

3. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, Multiple Stirling refrigerators (7) are arranged symmetrically at equal angles along the outer circumference of the Dewar (5).

4. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The mounting base (1) is a rigid plate structure with pre-drilled mounting holes at the four corners of the plate. The top surface of the mounting base (1) serves as a planar assembly reference surface, simultaneously supporting the three-phase asynchronous motor (2), the bearing seat (4), and the hollow high-temperature superconducting magnet.

5. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The three-phase asynchronous motor (2) is rigidly fixed to the front eccentric area of ​​the mounting base (1), and a drive pulley is provided at the output end; one end of the multi-wedge belt (3) is sleeved on the output pulley of the three-phase asynchronous motor (2), and the other end is sleeved on the hollow spindle pulley.

6. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The bearing seat (4) is vertically fixed in the middle of the mounting base (1), and a high-precision heavy-duty support bearing is integrated inside; the hollow spindle passes through the body of the bearing seat (4), one end is connected to the pulley, and the other end is rigidly connected to the Dewar (5).

7. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The Dewar (5) is a hollow cylindrical structure with a room temperature through hole in the center; the outer wall end face of the Dewar (5) is provided with a flange structure, and multiple sets of assembly threaded holes are evenly opened on the flange surface for rigidly fixing the refrigeration unit mounting base (6). Multiple refrigeration unit mounting bases (6) are distributed at equal angles around the Dewar (5), and the eccentric mass of each refrigeration unit cancels each other out during rotation, ensuring the dynamic balance performance of the whole machine.

8. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The Dewar (5) is also equipped with a copper cooling component (9), a magnet frame (10), and a high-temperature superconducting coil (11). The magnet frame (10) is made of a low thermal conductivity, high strength non-metallic low-temperature material and has a hollow ring structure. The high-temperature superconducting coil (11) is tightly wound and fixed to the outer periphery of the magnet frame (10). One side of the copper cooling component (9) is tightly pressed against the cold head (8), and the other side is attached to and covers the high-temperature superconducting coil (11) and the magnet frame (10).

9. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, The device also includes a conductive slip ring assembly, comprising an outer conductive slip ring (121) and an inner conductive slip ring (122); the outer conductive slip ring (121) is fixed to an external stationary frame, and the inner conductive slip ring (122) rotates synchronously with the Dewar (5) and the high-temperature superconducting coil (11); the conductive slip ring assembly is arranged in the ambient temperature region outside the left end of the Dewar (5) and does not extend into the vacuum cryogenic cavity inside the Dewar (5).

10. The compact hollow rotating superconducting magnet device with a Stirling refrigerator rotating in conjunction with the Stirling refrigerator according to claim 1, characterized in that, An independent electromagnetic shielding cylinder (13) with room temperature side is also provided on the inner wall of the room temperature through hole in the center of the Dewar (5); the electromagnetic shielding cylinder (13) is in a normal temperature environment throughout the process and does not come into contact with the low temperature cold mass inside the Dewar (5).

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