A low temperature superconducting heating device for heating a metal billet

Abstract

The application provides a low-temperature superconducting heating device for heating a metal rod ingot, which comprises a driving mechanism and a low-temperature superconducting magnet system; the low-temperature superconducting magnet system has a heating channel in the middle part; the driving mechanism drives the low-temperature superconducting magnet system to rotate axially; the metal rod ingot is arranged in the heating channel; the driving mechanism drives the low-temperature superconducting magnet system after being electrified to generate a high-efficiency rotating dynamic magnetic field to cut the metal rod ingot, so that the metal rod ingot is heated. The application innovatively provides a structure design of a permanent magnet hollow motor driving a low-temperature superconducting coil to rotate, realizes a uniform strong magnetic field, eddy current heating of 0.5-3T, realizes the construction of a dynamic rotating strong magnetic field with a rotating speed of 200-1500rpm, and breaks through from a static magnetic field to a dynamic rotating magnetic field, so that the metal rod is subjected to efficient and uniform magnetic field heating.

Description

Technical Field

[0001] This invention relates to the field of metal material heat treatment technology, and in particular to a low-temperature superconducting heating device for heating metal rods and ingots. Background Technology

[0002] Hot working of metal bars and ingots, as a key preliminary process for the forming and performance control of metal materials, directly determines the core competitiveness of national strategic high-end manufacturing industries such as aerospace, rail transportation, and energy equipment. In these fields, the heating quality of the initial billets for large-size, high-performance metal components, such as aero-engine turbine disks, heavy-duty gas turbine rotors, and large aluminum alloy structural parts, including heating uniformity, efficiency, and microstructure control, has a fundamental and far-reaching impact on the service performance and reliability of the final products. Therefore, developing efficient, precise, and widely adaptable metal bar and ingot heating technology has always been a core issue of continuous exploration in this field.

[0003] In the existing technological system, induction heating of metal rods and ingots mainly follows several different technical paths, as follows: High-Temperature Superconducting Induction Heating: The principle of this novel superconducting induction heating technology is that a DC-excited superconducting main magnet generates a strong DC magnetic field. An aluminum or copper workpiece rotates within this background DC magnetic field, cutting magnetic lines of force. This creates eddy currents within the workpiece, generating Joule heat that heats it to the processing temperature. The novel superconducting induction heating equipment mainly includes a DC excitation power supply, a superconducting main magnet system, and a mechanical rotation system.

[0004] Permanent magnet induction heating: This method utilizes a moving magnetic field to induce eddy currents within a metal ingot, thereby heating the metal. When the heater is operating, a motor drives a permanent magnet to rotate, creating a moving magnetic field. When the metal rod to be heated approaches this magnetic field, eddy currents are induced within the ingot, which then heat the metal. The eddy currents in permanent magnet heating are mainly concentrated on the workpiece surface, making it suitable for small to medium-sized parts and surface heat treatment.

[0005] Traditional induction heating: The principle of traditional induction heating technology is based on Faraday's law of electromagnetic induction and Joule-Lenz's law. Alternating current generates an alternating magnetic field, which induces eddy currents in the conductor. The Joule heating of these eddy currents is used to heat the conductor. Traditional induction heating systems mainly include an AC power supply, an AC induction copper coil, and a water cooling system. Traditional AC induction heating has low efficiency, approximately 45-50%. The copper coil itself has resistance, and when a large current is applied, the coil itself heats up, which is wasted energy. Furthermore, a large amount of water must be continuously used to cool the copper coil for heat dissipation. For large workpieces (such as large aluminum ingots used in aerospace), which require extremely high power, the efficiency of traditional induction heating is insufficient.

[0006] Therefore, how to innovatively design a novel induction heating system architecture that can leverage the advantages of superconducting technology to generate a strong magnetic field to ensure high heating efficiency, while fundamentally eliminating the reliance on mechanical rotation of large workpieces, and achieving relative motion with stationary workpieces by realizing the high-speed, stable rotation of the strong magnetic field itself, while effectively solving a series of engineering problems faced by rotating superconducting magnets, such as dynamic low-temperature cooling, structural stability at high speeds, and rotational power feeding, in order to achieve the goal of efficient, uniform, and low-cost heating of metal rods and ingots of various sizes and shapes, has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to propose a heating device that utilizes low-temperature superconducting technology to achieve efficient heating of metal rods and ingots.

[0008] To achieve the above objectives, the present invention proposes a low-temperature superconducting heating device for heating metal rods, comprising a driving mechanism and a low-temperature superconducting magnet system; The central part of the low-temperature superconducting magnet system is a heating channel, and the drive mechanism drives the low-temperature superconducting magnet system to achieve axial rotation. The metal rod is placed in the heating channel. The driving mechanism drives the low-temperature superconducting magnet system after it is powered on to generate an efficient rotating dynamic magnetic field to cut the metal rod, thereby heating the metal rod.

[0009] Furthermore, the drive mechanism is a permanent magnet hollow motor, including: a stationary base, a hollow stator assembly disposed on the stationary base, and a hollow rotor assembly coaxially disposed with the hollow stator assembly and rotatable relative to it; a low-temperature superconducting magnet system is integrated inside the hollow rotor assembly and rotates synchronously with it; The hollow stator assembly, hollow rotor assembly, and low-temperature superconducting magnet system together define a heating channel that runs along the central axis and is used to accommodate the metal rod ingot.

[0010] Furthermore, the hollow stator assembly includes a cylindrical stator core and a multiphase stator winding embedded in a slot in the inner wall of the stator core; the multiphase stator winding adopts a three-phase six-pole topology.

[0011] Furthermore, the hollow rotor assembly includes a cylindrical non-magnetic rotor support and a permanent magnet array fixed on the outer peripheral wall of the non-magnetic rotor support; The permanent magnet array is composed of multiple tile-shaped neodymium iron boron permanent magnets arranged in alternating polarities along the circumference and fixed to the outer surface of the non-magnetic rotor support with epoxy resin adhesive; the outer surface of the permanent magnet array is wrapped and cured with a layer of carbon fiber composite material with a thickness of 0.3 mm to provide structural constraints to resist centrifugal force.

[0012] Furthermore, the cryogenic superconducting magnet system is a fully enclosed cryogenic Dewar system, rigidly mounted within the internal cavity of the hollow rotor assembly; the cryogenic superconducting magnet system comprises, from the inside out: The central pipe serving as the heating channel, the superconducting coil wound around the outside of the central pipe, the inner cooler containing the superconducting coil and filled with liquid helium, the cold screen wrapped around the outside of the inner cooler, and the outer vacuum Dewar serving as the outermost vacuum insulation cavity. The drive end flange of the external vacuum Dewar is connected to the inner wall flange of the hollow rotor assembly by high-strength bolts, forming a rigid integrated rotating unit.

[0013] Furthermore, the superconducting coil is wound according to the configuration of a saddle-shaped coil winding to form a two-pole magnetic field structure, which generates a transverse gradient magnetic field in the heating channel.

[0014] Furthermore, it also includes an integrated dynamic interface assembly, which is fixed to one end of the stationary base and dynamically connected to the rotating end of the hollow rotor assembly and the cryogenic superconducting magnet system; the dynamic interface assembly includes a dynamic cryogenic fluid coupling device and a high-current conductive slip ring device.

[0015] Furthermore, the dynamic cryogenic fluid coupling device includes a fixed end and a rotating end; The fixed end includes a central supply pipeline and a coaxially arranged outer recovery pipeline, which are used to input 4.2K gaseous helium and recover 5.6K gaseous helium, respectively. The rotating end is connected to the cryogenic pipeline interface of the cryogenic superconducting magnet system; between the fixed end and the rotating end, at least two independent magnetohydrodynamic sealing structures are provided. Each magnetohydrodynamic sealing structure consists of a permanent magnet, a magnetic pole shoe, and a magnetic fluid injected therein, forming a non-contact rotating sealing barrier.

[0016] Furthermore, the high-current conductive slip ring device adopts a multi-channel liquid metal slip ring structure, which includes an insulating stationary ring made of silicon nitride ceramic material and a copper-based conductive rotating ring that rotates synchronously with the hollow rotor assembly; a gallium indium tin low-melting-point alloy is filled in the pre-set annular groove between the insulating stationary ring and the copper-based conductive rotating ring as a conductive medium; the high-current conductive slip ring device is provided with two main power channels for transmitting a rated 300A DC excitation current to the superconducting coil.

[0017] Furthermore, the low-temperature superconducting magnet system is divided along the axial direction into multiple standard heating modules with the same structure and function, and each standard heating module has an effective heating length of 500 mm; Multiple standard heating modules are arranged coaxially to extend the heating channel length of the cryogenic superconducting magnet system; the standard heating modules are connected by a central supply pipeline in series or parallel.

[0018] Compared with the prior art, the advantages of the present invention are: 1. The innovative architecture design of the permanent magnet hollow motor driving the rotation of the low temperature superconducting coil proposed in this invention realizes uniform strong magnetic field (0.5-3T) eddy current heating, and realizes the high temperature superconducting induction from the original static magnetic field (0.5-1T) to a dynamic rotating magnetic field with a speed of 200-1500rpm (0.5-3T).

[0019] 2. The innovative architecture design of the permanent magnet hollow motor driving the rotation of the low-temperature superconducting coil proposed in this invention features a dynamic rotating magnetic field with a fixed magnetic field strength. The superconducting coil current is stable, the strong magnetic field is fixed, and there is no alternating magnetic field, thus avoiding the AC loss that exists in the application of superconducting motors.

[0020] 3. The cooling system of the present invention has an architecture design based on "systems engineering" perspective, which can improve the reliability of the cooling system and reduce costs.

[0021] 4. Uniform magnetic field and efficient workpiece heating: The superconducting magnet is directly connected to the rotor of the hollow motor. As the rotor rotates, the high speed of the hollow motor drives the superconducting magnet to rotate, thereby achieving a uniform magnetic field and good workpiece heating effect.

[0022] 5. The gas-helium refrigeration seal of this invention adopts a unique sealing structure, and the superconducting magnet wiring is arranged through a conductive slip ring, which improves the safety and reliability of use.

[0023] 6. The structural design of the permanent magnet hollow motor driving the rotation of the low-temperature superconducting coil of the present invention has a through heating channel in the middle. The through heating channel allows standard heating modules to be added coaxially on both sides, thereby extending the heating length. This makes the low-temperature superconducting heating device of the present invention adaptable to heating metal rods of various lengths. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the low-temperature superconducting heating device for heating metal rods in an embodiment of the present invention; Figure 2 This is a schematic diagram of the low-temperature superconducting magnet system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the heating principle of the irregularly shaped hollow superconducting motor in an embodiment of the present invention; Figure 4 This is a schematic diagram of the magnetic field distribution of the rotating superconducting coil of the irregularly shaped hollow motor in an embodiment of the present invention; Figure 5 This is a linear comparison diagram of the central magnetic field strength of the superconducting coil of the pole coil structure and the central magnetic field strength of the single pole coil structure in an embodiment of the present invention; Figure 6 This is a schematic diagram of the parallel structure of the standard heating module in an embodiment of the present invention; Figure 7 This is a schematic diagram of the series structure of a standard heating module in an embodiment of the present invention. Detailed Implementation

[0025] 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.

[0026] like Figure 1 As shown, this invention discloses a low-temperature superconducting heating device for heating metal rods. It consists of a drive mechanism and a low-temperature superconducting magnet system. The central part of the low-temperature superconducting magnet system is a heating channel. The drive mechanism drives the low-temperature superconducting magnet system to rotate axially. The metal rod is placed inside the heating channel. The drive mechanism drives the energized low-temperature superconducting magnet system to generate a highly efficient rotating dynamic magnetic field that cuts the metal rod, thereby heating it. The principle is as follows: Figure 3 As shown; further as Figure 4 As shown, the magnetic field distribution of the rotating superconducting coil can be more uniform and more inclined to the central magnetic field. Compared with permanent magnet induction or AC induction heating, the magnetic field is mainly distributed on the outer edge of the circle; it can perform efficient and uniform induction heating of metal rods stationary in the central channel of the system.

[0027] The specific structure of the low-temperature superconducting heating device of this invention is as follows: The permanent magnet hollow motor of this invention includes a stationary base 1 serving as system support and positioning reference, a hollow stator assembly 2 fixedly mounted on the stationary base 1, a hollow rotor assembly 3 capable of high-speed rotation relative to the hollow stator assembly 2, and a low-temperature superconducting magnet system 4 rigidly integrated inside the hollow rotor assembly 3 and rotating synchronously with it. These three core functional components, namely the hollow stator assembly 2, the hollow rotor assembly 3, and the low-temperature superconducting magnet system 4, are arranged coaxially in structure, jointly defining a heating channel 5 that runs along the central axis of the motor for accommodating and heating the metal rod ingot. At the non-drive end of the motor, a key dynamic interface assembly is also provided to solve the engineering problem of stably delivering low-temperature medium and high current to the rotating components.

[0028] In this embodiment, the structure of the hollow stator assembly 2 is described in detail. The hollow stator assembly 2 includes a cylindrical stator core and a set of multi-phase stator windings embedded in slots in the inner wall of the stator core. The stator core is made of high-frequency, low-loss electrical silicon steel sheets of grade DW270-35, with a single sheet thickness precisely controlled at 0.2 mm. These sheets are formed into rings using a high-speed stamping process, then precisely aligned and stacked in a dedicated stacking fixture, and solidified along the outer edge using argon arc welding or laser welding to form an integral core structure with a pre-set inner slot. The selection of this grade and thickness of silicon steel sheet aims to effectively suppress iron losses caused by hysteresis and eddy current effects during high-frequency (typically several hundred hertz) motor drive. The inner diameter of the stator core is a key parameter, determined by adding the width of a radial air gap to the final outer diameter of the hollow rotor assembly. In this embodiment, the width of the radial air gap is set in the range of 0.5 mm to 1.5 mm to ensure sufficient electromagnetic coupling efficiency while reserving a safe clearance for the dynamic operation of the rotor.

[0029] The multiphase stator winding embedded in the stator core slot adopts a three-phase six-pole design in its topology. This design can achieve the best match with the number of permanent magnet poles on the hollow rotor assembly 3, generating a smooth driving torque and suppressing torque pulsation.

[0030] Corresponding to the hollow stator assembly 2, the hollow rotor assembly 3 is the rotating core of the entire system. It mainly consists of a cylindrical non-magnetic rotor support 31 and a ring of permanent magnets 32 fixed to the outer periphery of this support. The material selection for the non-magnetic rotor support 31 is crucial; it must simultaneously meet the stringent requirements of high mechanical strength, low density, and complete non-magnetism. In this embodiment, titanium alloy is used. The initial blank is obtained through an integral die forging process, followed by precision machining on a multi-axis CNC machining center. The high specific strength of titanium alloy enables it to withstand the enormous centrifugal force generated by high-speed rotation, while its low density helps reduce the rotor's moment of inertia, achieving a faster dynamic response. Its non-magnetic nature ensures that it will not interfere with the stator magnetic field or create a magnetic short circuit.

[0031] The permanent magnet array 32, fixed to the outer wall of the non-magnetic rotor support 31, is a key component for generating drive torque. This array is composed of multiple precision-ground tile-shaped permanent magnets spliced ​​circumferentially. The permanent magnet material is N52SH grade neodymium iron boron (NdFeB) rare-earth permanent magnet material. The "SH" grade indicates its high coercivity and upper operating temperature limit (up to 150℃), sufficient to handle the radiant heat transferred from the stator and the heat generated by the eddy current losses of the permanent magnets themselves during motor operation. During assembly, these tile-shaped magnets are arranged circumferentially in an alternating N-pole-S-pole-N-pole-S-pole sequence, forming a six-pole magnetic field structure that interacts with the three-phase six-pole electromagnetic field of the stator windings to generate drive torque. The permanent magnets are secured to the rotor support 31 using a dual-protection method: First, a high-strength, high-temperature resistant epoxy resin structural adhesive (such as Araldite AW106) is used to precisely bond them to the outer surface of the rotor support 31. Second, after all permanent magnets are installed and cured, carbon fiber prepreg is wrapped around their outer surface to form a 0.3 mm thick carbon fiber composite protective sleeve. This carbon fiber protective sleeve, after high-temperature curing, forms an integral constraint ring with extremely high tensile strength, providing structural constraint to resist the enormous centrifugal force experienced by the permanent magnets at the maximum design speed of 1500 rpm, preventing the magnets from loosening or flying off during operation.

[0032] As one of the core innovations of this invention, the cryogenic superconducting magnet system 4 is rigidly installed as an independent, fully enclosed cryogenic Dewar system within the internal cavity of the hollow rotor assembly 3. This integration allows the superconducting magnet to rotate synchronously as part of the rotor. Specifically, the structure of the cryogenic superconducting magnet system 4, from the inside out, includes: a central pipe 41 located at the very center, forming the inner wall of the heating channel 5; a superconducting coil frame surrounding the central pipe 41 for precisely winding the superconducting coil; a superconducting coil 42 wound on the frame; an inner cooler 43 housing the superconducting coil 42 and serving as a liquid helium (LHe) container; a cold shield 44 concentrically wrapped around the inner cooler 43 and maintained at an intermediate temperature range (e.g., 77K); and an outer vacuum Dewar 45 forming the outermost layer of the system and creating a high-vacuum insulating cavity. At the drive end, the end flange of the external vacuum Dewar 45 is fastened to the connecting flange machined on the inner wall of the non-magnetic rotor support 31 by multiple M16 high-strength TC4 titanium alloy bolts, thus forming a rigid, integrated rotating unit. The purpose of using titanium alloy bolts is to utilize their low thermal conductivity to reduce heat leakage from the ambient temperature rotor support to the cryogenic system.

[0033] In this embodiment, the superconducting coil 42 is wound using a composite superconducting wire. This wire is made by stranding 120 niobium-titanium (NbTi) superconducting filaments with a diameter of 0.05 mm with a high-purity oxygen-free copper matrix using a composite stranding process, resulting in a final outer diameter of 0.85 mm. The presence of the copper matrix provides mechanical support for the superconducting filaments and, in the event of an accidental quench in the superconducting coil, provides a temporary bypass path for the current, preventing the coil from burning out. The winding configuration of the superconducting coil 42 does not use a conventional solenoid configuration but is wound according to a precise saddle-shaped coil winding configuration. This configuration can generate a quadrupole transverse gradient magnetic field in the central region. When this gradient magnetic field rotates with the rotor, any part of the stationary metal ingot placed in the heating channel 5 will cut a magnetic flux that varies sinusoidally with time, thereby inducing a uniform circumferential eddy current. This magnetic field distribution characteristic fundamentally ensures the uniformity of heating, avoiding the problems of surface overheating or insufficient heating in the center that are common in traditional induction heating.

[0034] like Figure 5 As shown in the figure below, the simulation analysis results based on the model indicate that the central magnetic field strength of the superconducting coil with a two-pole coil structure is greater than that of the single-pole coil structure, and the magnetic field uniformity of the superconducting coil is also better. Therefore, a two-pole superconducting coil design is chosen to achieve a stronger central magnetic field.

[0035] To address the core engineering challenge of continuously supplying cryogenic medium (liquid helium or cryogenic gaseous helium) and stably transmitting hundreds of amperes of excitation current to a rotating cryogenic superconducting magnet system 4 at speeds up to 1500 rpm, this invention features an integrated dynamic interface assembly. This assembly is fixed to one end of the stationary base 1 and achieves dynamic fluid and electrical connections with the hollow rotor assembly 3 and the rotating end of the cryogenic superconducting magnet system 4. The dynamic interface assembly integrates two key subsystems: a dynamic cryogenic fluid coupling device and a high-current conductive slip ring device.

[0036] The dynamic cryogenic fluid coupling device is responsible for the leak-free transmission of cryogenic helium. It includes a fixed end connected to an external cryogenic supply device 7 and a rotating end that rotates synchronously with the internal cryogenic pipeline interface of the cryogenic superconducting magnet system 4. The fixed end is internally designed with a central supply pipeline and a coaxially fitted recovery pipeline, used to input 4.2K cryogenic gaseous helium into the inner cooling cylinder 43 and to recover gaseous helium whose temperature has risen to 5.6K after internal heat exchange, respectively. The key technology lies in the sealing structure of the fixed end and the rotating end. This invention employs two independent, series-arranged magnetohydrodynamic sealing structures. Each magnetohydrodynamic seal consists of a set of high-performance permanent magnets, precision-machined magnetic pole shoes, and nanoscale magnetic fluid pre-injected into the sealing gap. The strong magnetic field generated by the permanent magnets confines the magnetic fluid within the tiny gap between the pole shoes and the rotating shaft, forming multiple "O"-shaped annular liquid sealing barriers. This sealing method is non-contact, with virtually no friction or wear, and theoretically achieves zero leakage, fully meeting the sealing requirements for cryogenic gases under high-speed rotation and internal / external pressure differences. Furthermore, high-vacuum insulation jackets are designed between the supply and recovery pipelines, as well as on the entire outer casing of the device, to minimize heat leakage from the environment to the cryogenic fluid.

[0037] The high-current conductive slip ring device is used to transmit excitation current and monitoring signals. This device abandons the traditional carbon brush-copper ring structure, which is prone to wear, has high contact resistance, and generates electrical sparks, and instead adopts an advanced multi-channel liquid metal slip ring structure. Its main structure includes an insulating stationary ring made of silicon nitride (Si3N4) ceramic material, and a conductive rotating ring made of a highly conductive copper-based alloy that rotates synchronously with the rotor. Between the stationary ring and the conductive rotating ring, multiple interlocking annular grooves are precisely machined and pre-formed. These grooves are filled with a low-melting-point gallium indium tin eutectic alloy as the conductive medium. This liquid metal is liquid at room temperature and has extremely low resistivity and excellent conductivity. The slip ring device has two main power channels dedicated to transmitting a rated 300A DC excitation current to the superconducting coil 42. In addition, eight independent signal channels are integrated to transmit the weak voltage or current signals of multiple temperature sensors and superconducting liquid level sensors installed inside the cryogenic superconducting magnet system 4 without interference, thereby realizing real-time and accurate monitoring of the working status of the superconducting magnet.

[0038] like Figure 6 and Figure 7As shown, another important feature of this invention is the scalability of the cryogenic superconducting heating device, which is achieved through the segmented modular design of the cryogenic superconducting magnet system 4. The entire cryogenic superconducting magnet system is divided along the axial direction into multiple standard heating modules with identical structure and function. The effective heating length of each standard heating module is designed to be 500 mm. By adding standard heating modules of different lengths, the heating requirements of longer workpieces can be accommodated. Adjacent standard heating modules can be arranged as follows: Figure 6 Parallel connection as shown or as Figure 7 The central supply pipeline structure shown in the series is used to cool down each standard heating module, thereby allowing multiple standard heating modules to share a single cooling system and reducing equipment costs. This mode is mainly due to the structural design of the through heating channel, which allows multiple standard modules to be coaxially connected, extending the heating length and enabling the device to flexibly adapt to the heating of metal rods of different lengths.

[0039] Based on the aforementioned permanent magnet hollow motor system, this invention also provides a corresponding method for heating metal ingots. (Refer to...) Figure 4 The specific implementation steps of this method are as follows: S1, System Initialization. Before starting the heating task, a series of preparatory work is performed. The external vacuum pump group, consisting of a molecular pump and a mechanical pump, is activated to evacuate the vacuum insulation cavity of the cryogenic superconducting magnet system 4 (i.e., the space between the external vacuum Dewar 45, the inner cold cylinder 43, and the cold shield 44) ​​until the vacuum level is better than 10^-4 Pascals, in order to establish a good insulation environment. Subsequently, the matching cryogenic refrigerator (such as a GM refrigerator) is activated, and cryogenic gaseous helium is introduced into the inner cold cylinder 43 of the cryogenic superconducting magnet system 4 through a dynamic cryogenic fluid coupling device for pre-cooling and cooling until the internal temperature sensor shows that the temperature of the superconducting coil has stabilized at the operating point of 4.2K. After this, the superconducting coil 42 is energized at a slow rate of 1A / s through a high-current conductive slip ring device and a dedicated superconducting power supply until the current reaches the preset operating value according to process requirements (e.g., 300A), thereby establishing a stable and strong background magnetic field within the heating channel 5.

[0040] S2, Workpiece loading. The metal ingot to be heated is precisely conveyed to the center of the heating channel 5 by an upstream automated feeding mechanism (such as a roller conveyor or robotic arm), and is firmly fixed by clamping or supporting mechanisms at both ends of the workpiece to ensure that it remains absolutely stationary in the axial and radial positions throughout the heating process.

[0041] S3, Parameter Setting. The equipment operator inputs the specific parameters for this heating task through the human-machine interface of the control system. This includes the material type of the metal ingot to be heated, and the precise diameter and length values. Simultaneously, the target heating process curve is set, specifically including the heating rate of the heating section (unit: °C / min), the temperature setpoint of the holding section (unit: °C), and the holding duration (unit: min).

[0042] S4, Start Heating. After all parameters are confirmed to be correct, the operator starts the heating program. Immediately, the controller sends a command to the vector frequency converter, which smoothly starts and drives the hollow rotor assembly 3 and its internal low-temperature superconducting magnet system 4 to accelerate until the target speed is reached. The high-speed rotating strong magnetic field induces powerful circumferential eddy currents inside the stationary metal ingot, according to Faraday's law of electromagnetic induction. These eddy currents flow within the resistive metal body, generating a Joule heating effect, causing the ingot's temperature to rise rapidly.

[0043] Step S5, Heating Completion and Unloading. The heating process is complete when the preset holding timer expires. Induction heating is stopped. The heated and uniformly heated metal ingot is removed from heating channel 5 via an external unloading mechanism and sent to the next process, such as forging or extrusion.

[0044] To illustrate the beneficial effects of the technical solution of the present invention more specifically, an embodiment and a comparative example are provided below for comparison.

[0045] The low-temperature superconducting heating device described in this invention was used to heat an aluminum alloy 6061 ingot with a diameter of 400 mm and a length of 1200 mm. The device is equipped with three segmented low-temperature superconducting coil modules, using a parallel cooling mode. The target temperature was set to 500℃, and the initial room temperature was 25℃. The motor speed was set to 1000 rpm, and the excitation current was 300 A. During the heating process, the PLC main control unit dynamically fine-tuned the speed (fluctuation range ±15 rpm) based on infrared temperature measurement feedback to maintain a stable heating rate. Experimental records show that it took 28 minutes to heat from 25℃ to 500℃, the axial temperature uniformity (maximum temperature difference) of the workpiece was ±8℃, and the radial temperature gradient was less than 3℃. The total electrical energy consumed in the entire heating process was 186 kWh, of which the superconducting coil maintenance energy consumption was 22 kWh and the motor drive energy consumption was 164 kWh. The heating efficiency (defined as the ratio of the heat energy absorbed by the workpiece to the total input electrical energy) was calculated to be 76.3%.

[0046] In the comparative example, a conventional medium-frequency induction heating furnace was used to heat aluminum alloy 6061 ingots of the same specifications. The induction coil operated at a frequency of 1kHz and had a rated power of 200kW. Heating from 25℃ to 500℃ took 42 minutes. The maximum axial temperature difference of the workpiece reached ±25℃, and a significant skin effect was observed radially, with the surface temperature approximately 18℃ higher than the center. The total power consumption was 298kWh, and the heating efficiency was 48.1%.

[0047] The table below summarizes the key performance parameters of the embodiments and comparative examples: Furthermore, in another embodiment, a copper alloy ingot (800mm in length) with a rectangular cross-section of 300mm × 200mm was heated. Since the magnetic field of this invention is rotating and uniform in the central region, direct heating is possible without replacing the coil. The target temperature was set to 800℃, the rotation speed to 1200rpm, and the excitation current to 280A. The heating time was 35 minutes, and the temperature difference between the four corners and the center of the workpiece was less than ±10℃, demonstrating the good adaptability of this device to workpieces with non-circular cross-sections.

[0048] 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 low-temperature superconducting heating device for heating metal rods, characterized in that, Including the drive mechanism and the cryogenic superconducting magnet system; The central part of the low-temperature superconducting magnet system is a heating channel. The driving mechanism drives the low-temperature superconducting magnet system to rotate axially. The heating channel is a through-type heating channel.

2. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 1, characterized in that, The drive mechanism is a permanent magnet hollow motor, comprising: a stationary base, a hollow stator assembly disposed on the stationary base, and a hollow rotor assembly coaxially disposed with and rotatable relative to the hollow stator assembly; the low-temperature superconducting magnet system is integrated inside the hollow rotor assembly and rotates synchronously with it; The hollow stator assembly, the hollow rotor assembly, and the low-temperature superconducting magnet system together define a heating channel that runs along the central axis and is used to accommodate the metal rod ingot.

3. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 2, characterized in that, The hollow stator assembly includes a cylindrical stator core and a multiphase stator winding embedded in a groove in the inner wall of the stator core.

4. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 3, characterized in that, The hollow rotor assembly includes a cylindrical non-magnetic rotor support and a permanent magnet array fixed on the outer peripheral wall of the non-magnetic rotor support. The permanent magnet array is composed of multiple tile-shaped neodymium iron boron permanent magnets arranged in alternating polarities along the circumference and fixed to the outer surface of the non-magnetic rotor support with adhesive; the outer surface of the permanent magnet array is wrapped and cured with a layer of carbon fiber composite material to provide structural constraints to resist centrifugal force.

5. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 2, characterized in that, The cryogenic superconducting magnet system is a fully enclosed cryogenic Dewar system, rigidly mounted within the internal cavity of the hollow rotor assembly; the cryogenic superconducting magnet system comprises, from the inside out: The heating channel consists of a central pipe, a superconducting coil wound around the outside of the central pipe, an inner cooler containing the superconducting coil and filled with liquid helium, a cold screen wrapped around the outside of the inner cooler, and an outer vacuum Dewar that serves as the outermost vacuum insulation cavity. The drive end flange of the external vacuum Dewar is connected to the inner wall flange of the hollow rotor assembly by bolts, forming a rigid, integrated rotating unit.

6. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 5, characterized in that, The superconducting coil is wound in the configuration of a saddle-shaped coil winding to form a two-pole magnetic field structure, which generates a transverse gradient magnetic field within the heating channel.

7. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 2, characterized in that, It also includes an integrated dynamic interface assembly, which is fixed to one end of the stationary base and dynamically connected to the hollow rotor assembly and the rotating end of the cryogenic superconducting magnet system; the dynamic interface assembly includes a dynamic cryogenic fluid coupling device and a high-current conductive slip ring device.

8. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 7, characterized in that, The dynamic cryogenic fluid coupling device includes a fixed end and a rotating end; The fixed end includes a central supply pipeline and a coaxially arranged outer recovery pipeline, which are used to input cooled gaseous helium and recover heated gaseous helium, respectively. The rotating end is connected to the cryogenic pipeline interface of the cryogenic superconducting magnet system; between the fixed end and the rotating end, at least two independent magnetohydrodynamic sealing structures are provided, each of which consists of a permanent magnet, a magnetic pole shoe and a magnetic fluid injected therein, forming a non-contact rotating sealing barrier.

9. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 7, characterized in that, The high-current conductive slip ring device adopts a multi-channel liquid metal slip ring structure, which includes an insulating stationary ring body and a copper-based conductive rotating ring that rotates synchronously with the hollow rotor assembly; a low-melting-point alloy is filled in the pre-set annular groove between the insulating stationary ring body and the conductive rotating ring as a conductive medium; the high-current conductive slip ring device is provided with two main power channels for transmitting DC excitation current to the superconducting coil.

10. The low-temperature superconducting heating device for heating metal rods and ingots according to claim 7, characterized in that, The low-temperature superconducting magnet system is divided into multiple standard heating modules with the same structure and function along the axial direction. Multiple standard heating modules are arranged coaxially to extend the heating channel length of the low-temperature superconducting magnet system; the standard heating modules are connected in series or in parallel by the central supply pipeline.

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