An axial joul heat sintering and radial pressure integrated super long bar continuous powder forming device and method

Abstract

The application discloses an axial Joule heat sintering and radial pressure integrated super-long rod continuous powder forming device and method, which comprises a base and a closed-loop control system. A sintering bin is arranged on the base. A radial pressure mechanism is arranged above the sintering bin. The radial pressure mechanism comprises an upper pressure head and a driving source for driving the upper pressure head to move up and down. A bin door is arranged at the feeding end of the sintering bin, and an automatic powder supplementing mechanism is arranged on the same side. The automatic powder supplementing mechanism comprises a hopper and an automatic unloading valve. A telescopic support is arranged on the other side of the automatic powder supplementing mechanism. A first electrode is fixedly connected to the movable end of the telescopic support. A second electrode is arranged at the discharging end of the sintering bin. An axial Joule heat power source is electrically connected to the first electrode and the second electrode. The closed-loop control system is respectively connected to the telescopic support, the automatic unloading valve, the bin door, the driving source of the upper pressure head and the axial Joule heat power source. The device realizes the coupling of a thermal field and a force field, and breaks through the limitation of the size of materials in traditional single forming of pressure sintering.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy, specifically relating to a continuous powder forming device and method for ultra-long rods that integrates axial Joule thermal sintering and radial pressure. Background Technology

[0002] With the development of materials towards larger sizes, greater uniformity, and higher performance, the instability of traditional batch production methods has become increasingly prominent. Powder metallurgy is a typical example of batch production. Quality instability issues frequently arise due to variations in equipment, raw materials, processes, personnel, and environment. The root cause lies in the close relationship between the high uniformity of the temperature field and material properties. On the one hand, larger equipment can reduce batches, increase yield and stability, and reduce energy consumption; on the other hand, with the increase in the size of sintering equipment, the uniformity of the furnace temperature field decreases, leading to a deterioration in material properties. This creates a limitation on the weight of powder-sintered ingots, and further hinders the production of high aspect ratio bars through pressure processing. Moreover, even bars with a large aspect ratio sintered using existing equipment are prone to bending during sintering, requiring secondary straightening for later forging or extrusion. This not only reduces production efficiency but also increases energy and material consumption, and often results in defective products due to inadequate temperature and stress control, reducing yield and increasing material manufacturing costs. Therefore, producing high linearity and large aspect ratio bars has always been a technical challenge in the powder metallurgy industry.

[0003] For the fabrication of high aspect ratio bars, three main issues need to be addressed: forming efficiency, straightness, and continuity. To improve the densification effect during sintering, powder metallurgy sintering has evolved from simple hot-field sintering to various multi-field coupling methods. Hot pressing (HP) emerged in the 1930s, which involves heating while applying unidirectional mechanical pressure. Densification is promoted through the synergistic effect of thermal activation and pressure drive. However, the heat is conducted from the outside in, resulting in slow heating, long holding times, and excessive grain growth, making it difficult to fabricate complex-shaped, high-performance parts. To overcome these shortcomings, spark plasma sintering (SPS) was developed in the 1990s. This method uses pulsed direct current to directly heat the mold and powder, achieving rapid heating (up to several hundred degrees Celsius per minute) through Joule heating. Simultaneously, the current-induced plasma discharge removes the oxide film on the powder surface, promotes interfacial diffusion, significantly shortens the sintering time, and inhibits grain coarsening. The subsequent Joule heating rapid hot pressing sintering (Flash Sintering) further achieved thermal runaway densification within seconds using extremely high current densities (>100 A / cm²), compressing the sintering cycle to minutes or even seconds and significantly reducing energy consumption. Both technologies replace traditional external radiation heating with "direct current heating," solving the core problems of slow heating, low efficiency, and grain growth in hot pressing sintering. However, all of the above technologies adopt an axial pressure mode, with the blank's radial direction passively constrained only by the mold. This results in uneven radial shrinkage of the sintered body, low density in the central region, and concentrated residual stress, severely restricting the consistency and reliability of product performance.

[0004] To address the linearity issue, Viktors Mironov's team systematically proposed a magnetic pulse powder pressing (MPC) device in 2025. This device utilizes capacitor discharge to generate a pulsed magnetic field, driving a conductive sheath or punch to apply high-speed radial / axial dynamic pressure to the powder. The aim is to solve the problems of low pressure and difficulty in forming complex and long components using traditional static pressing. However, this device is only a cold pressing method and lacks Joule heating sintering capabilities, making it impossible to achieve simultaneous coupling of radial pressing and axial Joule heating sintering. Meanwhile, existing manufacturing processes for ultra-long rods still commonly employ segmented sintering followed by mechanical splicing. The splicing interfaces easily retain original particle boundaries, oxide layers, and contaminants, forming natural weak points and crack initiation sources, ultimately leading to significant deterioration in the overall strength, fatigue life, and dimensional stability of the product.

[0005] To address the issue of continuous production, Lu Haigang and others from Taiyuan Saiyin New Material Technology Co., Ltd. applied for an intermittent rapid Joule heating high-temperature furnace in 2025. This furnace utilizes a movable sliding frame to achieve intermittent cycles of feeding, sintering, and discharging. Combined with axial pre-compression to optimize Joule heating conduction conditions, it solves the problems of continuous production and low efficiency associated with traditional Joule heating devices. However, this device only employs unidirectional axial pre-compression, lacking effective radial constraint and exhibiting poor straightness. Furthermore, its "intermittent cycle" is essentially still a single-mold, single-time, intermittent molding process, lacking true continuous progressive molding capability and still unable to achieve integrated, seamless fabrication of ultra-long bars. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide an integrated continuous powder forming device and method for ultra-long rods that combines axial Joule thermal sintering and radial pressurization. This method solves the problems of short circuits, crosstalk, and high-temperature failures caused by axial energization and radial pressurization, and enables rapid forming of high-density, high-performance powder blanks. At the same time, it breaks through the size limitations of traditional single-stage forming and realizes the integrated continuous preparation of ultra-large aspect ratio rods.

[0007] This invention is achieved through the following technical solution: A continuous powder forming device for ultra-long rods integrating axial Joule hot sintering and radial pressurization includes a base and a closed-loop control system. A sintering chamber is mounted on the base, and a radial pressurization mechanism is positioned above the sintering chamber. The radial pressurization mechanism includes an upper pressure head and a drive source for moving the upper pressure head up and down. Slide rails are provided on both sides of the upper pressure head for guidance. A chamber door is provided at the feed end of the sintering chamber, and an automatic powder replenishment mechanism is located on the same side. The automatic powder replenishment mechanism includes a hopper and an automatic discharge valve for quantitatively replenishing powder into the sintering chamber. Finally, a telescopic bracket is provided on the other side of the automatic powder replenishment mechanism. A first electrode is fixedly connected to the movable end of the telescopic bracket. The telescopic bracket is used to drive the first electrode to move axially to move the sintered rod, and to drive the first electrode to reset and push the newly replenished powder into the sintering chamber. A second electrode is provided at the discharge end of the sintering chamber. The second electrode passes through the end face of the sintering chamber and is used to contact the end face of the billet. An axial Joule heating power supply is electrically connected to the first electrode and the second electrode through a wire to provide sintering current. The closed-loop control system is connected to the drive source of the telescopic support, the automatic unloading valve, the silo door, the upper pressure head, and the axial Joule heating power supply, respectively, and is used to control the coordinated action of each component according to the timing sequence.

[0008] Furthermore, the inner wall of the sintering chamber and the surface of the upper pressure head that contacts the sintering chamber are both provided with a BN insulating coating to isolate the axial Joule thermal current from the radial pressurization mechanism; the sintering chamber is connected to a sintering chamber vacuum module for performing vacuuming or vacuum breaking operations on the sintering chamber.

[0009] Furthermore, an exchange chamber is provided on one side of the feed end of the sintering chamber and is located below the discharge end of the hopper. The exchange chamber is connected to a vacuum module for performing vacuuming or vacuum breaking operations on the exchange chamber.

[0010] Furthermore, a cooling chamber is provided on one side of the discharge end of the sintering chamber. The inner wall of the cooling chamber is provided with a BN insulating coating. A circulating water cooling system is arranged on the outer side of the cooling chamber along the displacement path of the sintered bar to perform point cooling on the sintered section after displacement.

[0011] A continuous powder forming method for ultra-long rods integrating axial Joule thermal sintering and radial pressurization based on any one of the aforementioned devices includes the following steps: Step 1: Control the silo door to open through the closed-loop control system, control the automatic unloading valve to fill the sintering silo with the first section of powder, then control the first electrode, the second electrode and the upper pressure head to apply pressure synchronously for pre-pressing, and control the axial Joule heating power supply to be energized, using the powder's own resistance to generate Joule heat for sintering, forming the first section of bar. Step 2: After the first section of the bar is sintered, the telescopic support is controlled by the closed-loop control system to drive the first electrode to move, which in turn moves the sintered bar and the second electrode to a preset position, so that all or part of the first section of the bar is moved out of the sintering chamber and a powder replenishment space is formed on the feeding side of the sintering chamber. Step 3: Control the telescopic bracket to reset the first electrode through the closed-loop control system, and control the automatic unloading valve to open, so that the hopper quantitatively fills the next section of powder into the powder replenishment space. Step 4: Control the telescopic bracket to drive the first electrode through the closed-loop control system, push the next section of powder into the sintering chamber, and make close contact with the end of the previous section of the rod. At the same time, control the first electrode, the second electrode and the upper pressure head to apply pressure synchronously for pre-compression. Step 5: Control the axial Joule heating power supply to be powered on again through the closed-loop control system to perform Joule heating sintering on the next section of powder, making it dense and forming a high-temperature metallurgical bond with the end of the previous section of the rod. Step 6: Repeat steps 2 to 5, stacking segments one by one to form the rod until the target length of the ultra-large height-to-diameter ratio integrated rod is obtained.

[0012] Furthermore, before performing step 1, the exchange chamber and sintering chamber are evacuated to a high vacuum state by using the vacuum modules of the exchange chamber and sintering chamber.

[0013] Furthermore, in step 3, after the first electrode is reset, the chamber door is closed by the closed-loop control system, the vacuum module of the exchange chamber is used to break the vacuum in the exchange chamber, and then the automatic unloading valve is opened.

[0014] Furthermore, before performing step 4, the exchange chamber is evacuated again to a high vacuum state consistent with that of the sintering chamber through the exchange chamber vacuum module, and then the chamber door is opened by the closed-loop control system.

[0015] Furthermore, in step 2, after the sintered bar stock is moved out of the sintering chamber, it enters the cooling chamber, where the sintered bar stock segment is cooled at specific points by a circulating water cooling system.

[0016] Furthermore, during the cycle of steps 2 to 5, the sintering chamber is kept in a high vacuum state and no vacuum breaking operation is performed. When the bar reaches the target length, the vacuum breaking operation is performed on the sintering chamber to remove the bar.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention significantly improves the density, microstructure uniformity, and structural integrity of the billet by coupling axial Joule thermal sintering with radial mechanical pressure throughout the entire process, combined with a continuous integrated progressive forming process. This enables the seamless, defect-free, and linear integrated fabrication of ultra-long bars, greatly enhancing the mechanical properties and reliability of the products. It truly breaks through the bottleneck in the fabrication of large-size components using powder metallurgy, providing a completely new solution for the industrial production of ultra-large aspect ratio bars. This invention achieves coupled forming of thermal and force fields, overcoming the limitations on material size imposed by traditional pressure sintering in a single-stage process.

[0018] 1. Using BN insulating coating as the molding carrier and electrical isolation layer, the axial Joule thermal circuit and radial pressurization mechanism are completely isolated, eliminating short circuits, current leakage and electromagnetic interference from the source, solving the electrical safety hazards of traditional metal mold pressurization, and ensuring synchronous and stable operation of sintering and pressurization.

[0019] 2. Simultaneous axial Joule heating and rapid internal sintering, combined with radial hydrostatic pressing, create a coupled densification effect of "radial compressive stress + internal Joule heating," significantly improving the density and uniformity of the billet and eliminating forming defects such as density gradients, delamination, and cracking. The billet density can reach over 97%, with fine and uniform grain structure, free from density gradients, delamination, and cracking defects. The forming performance is close to that of hot isostatic pressing, and the product consistency is significantly better than that of traditional processes.

[0020] 3. The pure mechanical radial pressure structure is adopted to keep the powder under pressure in the pressure section uniform, with no electromagnetic interference, low failure rate and low maintenance cost. All moving and pressure core components are arranged outside the high temperature sintering zone to avoid high temperature softening, jamming, wear and high temperature failure, which significantly improves the stability of equipment operation and service life.

[0021] 4. Through a cyclical forming structure and process of electrode shifting, resetting and powder replenishment, and pushing and pressing, the electrode carries the billet to move and avoid obstacles after sintering. One side of the electrode is reset in conjunction with automatic powder replenishment and pushing, realizing uninterrupted progressive sintering. The forming length can be infinitely stacked, breaking through the size limitations of traditional equipment, realizing the integrated continuous preparation of ultra-large aspect ratio bars, completely eliminating the segmented splicing process, completely eliminating splicing interface defects, and significantly improving the overall structural strength and mechanical integrity of ultra-long bars. 5. The entire process adopts closed-loop sequential automatic control, automated continuous production, and realizes the automatic matching of all processes such as shifting, powder replenishment, material pushing, pressurization and sintering, ensuring the consistency of the process of each section of the formed blank. The overall performance of the ultra-long bar is uniform and the structure is complete. Compared with the traditional intermittent single forming process, the production efficiency is increased by several times, which is suitable for the large-scale preparation of ultra-long components.

[0022] 6. This device can be adapted to the forming and processing of various powder systems such as metals, ceramics, composite materials, and high-entropy alloys. It not only meets the needs of conventional billet forming, but also adapts to the preparation of ultra-large diameter special rods, and has a wide range of applications. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention; Figure 2 This is a schematic diagram of the continuous powder forming method of the present invention.

[0024] In the diagram: 1. Telescopic support; 2. First electrode; 3. Vacuum module of the exchange chamber; 4. Hopper; 5. Automatic unloading valve; 6. Exchange chamber; 7. Chamber door; 8. Slide rail; 9. Vacuum module of the sintering chamber; 10. Sintering chamber; 11. Upper pressure head; 12. BN insulating coating; 13. Second electrode; 14. Base; 15. Circulating water cooling system; 16. Wire; 17. Cooling chamber. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0026] refer to Figure 1 As shown, this invention provides an integrated continuous powder forming device for ultra-long rods that combines axial Joule thermal sintering and radial pressurization. It integrates axial Joule thermal sintering and radial pressurization technologies and extends them to the continuous integrated production of ultra-long rods. Axial Joule thermal sintering can achieve rapid heating in seconds by directly penetrating the powder with current, fundamentally suppressing the grain coarsening problem caused by long-term heat preservation in traditional hot pressing. The simultaneously applied radial pressurization can eliminate the density gradient caused by the free shrinkage of the billet, making the cross-section of the rod uniform in density. Based on this, combined with continuous powder feeding and segmented continuous sintering, ultra-long rods can be formed in one piece, completely avoiding interface defects and performance degradation caused by segmented splicing.

[0027] The device can achieve continuous cyclic operation of single-cycle powder loading and sintering, electrode shifting, resetting and powder replenishment, and progressive pressing and sintering without stopping the machine to disassemble the mold and remove parts. It can infinitely extend the length of the billet and prepare ultra-large aspect ratio integrated bars. The specific description is as follows: It includes a horizontally axially arranged base 14 and a closed-loop control system. A sintering chamber 10 is set on the base 14. A radial pressing mechanism is set above the sintering chamber 10. The radial pressing mechanism includes an upper pressing head 11 and a driving source for driving the upper pressing head to move up and down. Slide rails 8 are set on both sides of the upper pressing head 11 for guidance. The feeding end of the sintering chamber 10 is provided with a chamber door 7, and an automatic powder replenishing mechanism is set on the same side. The automatic powder replenishing mechanism includes a hopper 4 and an automatic unloading valve 5 for quantitatively replenishing powder into the sintering chamber 10. In this embodiment, the powder hopper 4 is a conical powder storage hopper. A telescopic bracket 1 is provided on the other side of the dynamic powder replenishment mechanism. A high-temperature resistant and high-strength first electrode 2 is fixedly connected to the movable end of the telescopic bracket 1. The telescopic bracket 1 is used to drive the first electrode 2 to move axially to move the sintered rod, and to drive the first electrode 2 to reset and push the newly replenished powder into the sintering chamber 10. A high-temperature resistant and high-strength second electrode 13 is provided at the discharge end of the sintering chamber 10. The second electrode 13 passes through the end face of the sintering chamber and is used to contact the end face of the billet. An axial Joule heating power supply is electrically connected to the first electrode 2 and the second electrode 13 through a wire 16 to provide sintering current. In this embodiment, the axial Joule heating power supply is a low-voltage, high-current adjustable power supply. It generates Joule heat through the resistance of the powder itself to achieve rapid and uniform heating and sintering. The heating rate is fast and the temperature field is uniform, which is suitable for continuous segmented sintering. The closed-loop control system is connected to the drive source of the telescopic support 1, the automatic unloading valve 5, the silo door 7, the upper pressure head 11, and the axial Joule heating power supply, respectively, and is used to control the coordinated action of each component according to the timing sequence.

[0028] The inner wall of the sintering chamber 10 and the surface of the upper pressure head 11 that contacts the sintering chamber 10 are both provided with a BN insulating coating 12 to isolate the axial Joule thermal current from the radial pressurization mechanism. A sintering chamber vacuum module 9 is connected to the sintering chamber 10 for vacuuming or breaking the vacuum. The upper pressure head 11 can move up and down, providing stable pressure during sintering, lifting to avoid interference when the electrode moves, and pressing down again after powder replenishment to complete the cyclic radial mechanical pressurization.

[0029] The sintering chamber 10 has an exchange chamber 6 on one side of the feed end, and is located below the discharge end of the hopper 4. The exchange chamber 6 is connected to an exchange chamber vacuum module 3, which is used to perform vacuuming or vacuum breaking operations on the exchange chamber 6.

[0030] The sintering chamber 10 and the exchange chamber 6 adopt a dual vacuum partition design. The entire chamber is evacuated before sintering. After sintering, the sintering chamber 10 is sealed to maintain vacuum. The exchange chamber 6 is filled with gas to replenish powder. After the powder replenishment is completed, the exchange chamber is evacuated again to the same level as the sintering chamber 10, so as to realize continuous powder loading and sintering in a vacuum environment and avoid material oxidation.

[0031] A cooling chamber 17 is provided on one side of the discharge end of the sintering chamber 10. The inner wall of the cooling chamber 17 is coated with a BN insulating coating 12. A circulating water cooling system 15 is arranged on the outer side of the cooling chamber 17 along the displacement path of the sintered bar, which is used to cool the sintered section after displacement at a fixed point. The overall structure is adapted to the lateral displacement stroke of the electrode and does not interfere with the continuous forming process. All moving parts in this device are arranged outside the high-temperature zone to avoid high-temperature failure and ensure continuous and stable operation. In this embodiment, the sintered bar section after right displacement is cooled by fixed-point, rapid and uniform water cooling, which can accurately cool the formed billet, while the unsintered area on the left side maintains the normal process temperature, realizing segmented differentiated temperature control, and effectively solving the problems of excessive overall temperature accumulation, slow cooling and large residual heat in the billet during the continuous forming process of ultra-long bars.

[0032] Key circuit and forming principle: The axial Joule thermal current is completely confined to the contact circuit between the electrode and the billet, and the radial pressure mechanism is electrically isolated throughout the process, with no circuit coupling interference; through the segmented progressive sintering method, each newly sintered billet is integrated with the previous billet at high temperature, without splicing interface, and through multiple cycles of superposition, the overall length of the bar is continuously extended, and finally a complete ultra-large height-to-diameter ratio integrated bar is formed.

[0033] Based on the aforementioned continuous powder forming apparatus, this invention enables multi-cycle progressive sintering to continuously produce seamless, dense, ultra-large aspect ratio rods. A schematic diagram of the apparatus's workflow is shown below. Figure 2 As shown, the specific continuous molding steps are as follows: Step 1: The exchange chamber 6 and sintering chamber 10 are evacuated to a high vacuum state through the exchange chamber vacuum module 3 and the sintering chamber vacuum module 9 to prevent powder oxidation. Then, powders such as metals, ceramics or high-entropy alloys are quantitatively loaded into the hopper 4. The hopper door 7 is opened by the closed-loop control system, and the automatic unloading valve 5 is controlled to fill the hopper 4 with the first section of powder into the sintering chamber 10. Then, the first electrode 2, the second electrode 13 and the upper pressure head 11 are controlled to apply pressure synchronously to pre-compress the powder to complete the powder densification pre-compressing. The axial Joule heating power supply is energized to generate Joule heat using the powder's own resistance to sinter and form the first section of rod. Step 2: After the first section of the rod is sintered, the telescopic bracket 1 is controlled by the closed-loop control system to drive the left first electrode 2 to move, which drives the sintered rod and the right second electrode 13 to move synchronously to the preset position, so that all or part of the first section of the rod is moved out of the sintering chamber 10, and a powder replenishment space is formed on the feeding side of the sintering chamber 10. The entire process is carried out without cooling, demolding, or interruption of equipment operation, and the sintered rod is moved out of the sintering chamber 10 and enters the cooling chamber 17. The sintered rod section is cooled at fixed points by the circulating water cooling system 15. Step 3: Control the telescopic bracket 1 to drive the left first electrode 2 to reset through the closed-loop control system, control the chamber door 7 to close through the closed-loop control system, perform vacuum breaking operation on the exchange chamber 6 through the exchange chamber vacuum module 3, and then control the automatic unloading valve 5 to open, so that the hopper 4 quantitatively fills the next section of powder into the powder replenishment space. Step 4: First, the exchange chamber 6 is evacuated again to a high vacuum state consistent with the sintering chamber 10 through the exchange chamber vacuum module 3. Then, the chamber door 7 is opened and quantitatively filled with the next section of powder through the closed-loop control system. The telescopic bracket 1 is driven by the closed-loop control system to push the next section of powder into the sintering chamber 10 and make it in close contact with the end of the previous section of the rod. At the same time, the first electrode 2, the second electrode 13 and the upper pressure head 11 are controlled to apply pressure synchronously for pre-compression, so that the new powder is in close contact with the previous section of the rod. Step 5: Control the axial Joule heating power supply to be powered on again through the closed-loop control system to perform Joule heating sintering on the next section of powder, making it dense and forming a high-temperature metallurgical bond with the end of the previous section of the rod. The rod as a whole is free of delamination and splicing defects. Step 6: Repeat steps 2 to 5, stacking segments one by one to form the rod, continuously extending the length of the rod until the target length of the ultra-large aspect ratio integrated rod is obtained.

[0034] During the cycle of steps 2 to 5, the sintering chamber 10 is kept in a high vacuum state and no vacuum breaking operation is performed. When the bar reaches the target length, the vacuum breaking operation is performed on the sintering chamber 10 to remove the bar.

Claims

1. A continuous powder forming apparatus for ultra-long rods integrating axial Joule hot sintering and radial pressurization, characterized in that, The system includes a base (14) and a closed-loop control system. A sintering chamber (10) is mounted on the base (14). A radial pressurizing mechanism is mounted above the sintering chamber (10). The radial pressurizing mechanism includes an upper pressure head (11) and a drive source for moving the upper pressure head up and down. Slide rails (8) are provided on both sides of the upper pressure head (11) for guidance. A chamber door (7) is provided at the feed end of the sintering chamber (10), and an automatic powder replenishing mechanism is provided on the same side. The automatic powder replenishing mechanism includes a hopper (4) and an automatic unloading valve (5) for quantitatively replenishing powder into the sintering chamber (10). An automatic powder replenishing mechanism is provided on the other side. A telescopic support (1) is provided, with a first electrode (2) fixedly connected to the movable end of the telescopic support (1). The telescopic support (1) is used to drive the first electrode (2) to move axially to move the sintered rod material, and to drive the first electrode (2) to reset and push the newly added powder into the sintering chamber (10). A second electrode (13) is provided at the discharge end of the sintering chamber (10). The second electrode (13) passes through the end face of the sintering chamber and is used to contact the end face of the billet. An axial Joule heating power supply is electrically connected to the first electrode (2) and the second electrode (13) through a wire (16) to provide sintering current. The closed-loop control system is connected to the drive source of the telescopic support (1), the automatic unloading valve (5), the silo door (7), the upper pressure head (11), and the axial Joule heating power supply, respectively, and is used to control the coordinated action of each component according to the timing sequence.

2. The integrated axial Joule hot sintering and radial pressurization device for continuous powder forming of ultra-long rods according to claim 1, characterized in that, The inner wall of the sintering chamber (10) and the surface of the upper pressure head (11) that contacts the sintering chamber (10) are provided with a BN insulating coating (12) to isolate the axial Joule thermal current from the radial pressure mechanism; the sintering chamber (10) is connected to a sintering chamber vacuum module (9) for performing vacuuming or vacuum breaking operations on the sintering chamber (10).

3. The integrated axial Joule hot sintering and radial pressurization device for continuous powder forming of ultra-long rods according to claim 1, characterized in that, The sintering chamber (10) has an exchange chamber (6) on one side of the feed end, and is located below the discharge end of the hopper (4). The exchange chamber (6) is connected to an exchange chamber vacuum module (3) for vacuuming or breaking the vacuum of the exchange chamber (6).

4. The integrated axial Joule hot sintering and radial pressurization device for continuous powder forming of ultra-long rods according to claim 1, characterized in that, A cooling chamber (17) is provided on one side of the discharge end of the sintering chamber (10). The inner wall of the cooling chamber (17) is provided with a BN insulating coating (12). A circulating water cooling system (15) is arranged on the outer side of the cooling chamber (17) along the displacement path of the sintered bar, which is used to cool the sintered section at a fixed point after displacement.

5. A method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization based on the apparatus described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Control the silo door (7) to open through the closed-loop control system, control the automatic unloading valve (5) to fill the hopper (4) into the sintering silo (10) with the first section of powder, then control the first electrode (2), the second electrode (13) and the upper pressure head (11) to apply pressure synchronously for pre-pressing, and control the axial Joule heating power supply to be energized, using the powder's own resistance to generate Joule heat for sintering, forming the first section of bar material; Step 2: After the first section of the rod is sintered, the telescopic support (1) is controlled by the closed-loop control system to drive the first electrode (2) to move, and the sintered rod and the second electrode (13) are moved synchronously to the preset position, so that all or part of the first section of the rod is moved out of the sintering chamber (10) and a powder replenishment space is formed on the feeding side of the sintering chamber (10). Step 3: Control the telescopic bracket (1) through the closed-loop control system to drive the first electrode (2) to reset, and control the automatic unloading valve (5) to open, so that the hopper (4) quantitatively fills the next section of powder into the powder replenishment space; Step 4: Control the telescopic bracket (1) through the closed-loop control system to drive the first electrode (2) to push the next section of powder into the sintering chamber (10) and make it in close contact with the end of the previous section of the rod. At the same time, control the first electrode (2), the second electrode (13) and the upper pressure head (11) to apply pressure synchronously for pre-pressing. Step 5: Control the axial Joule heating power supply to be powered on again through the closed-loop control system to perform Joule heating sintering on the next section of powder, making it dense and forming a high-temperature metallurgical bond with the end of the previous section of the rod. Step 6: Repeat steps 2 to 5, stacking segments one by one to form the rod until the target length of the ultra-large aspect ratio integrated rod is obtained.

6. The method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization according to claim 5, characterized in that, Before performing step 1, the exchange chamber (6) and sintering chamber (10) are evacuated to a high vacuum state by the exchange chamber vacuum module (3) and sintering chamber vacuum module (9).

7. The method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization according to claim 6, characterized in that, In step 3, after the first electrode (2) is reset, the chamber door (7) is closed by the closed-loop control system, the vacuum module (3) of the exchange chamber (6) is used to break the vacuum, and then the automatic unloading valve (5) is opened.

8. The method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization according to claim 7, characterized in that, Before performing step 4, the exchange chamber (6) is evacuated again to a high vacuum state consistent with the sintering chamber (10) by the exchange chamber vacuum module (3), and then the chamber door (7) is opened by the closed-loop control system.

9. The method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization according to claim 5, characterized in that, In step 2, the sintered bar is moved out of the sintering chamber (10) and into the cooling chamber (17), where the sintered bar segment is cooled at a fixed point by the circulating water cooling system (15).

10. The method for continuous powder forming of ultra-long rods integrating axial Joule thermal sintering and radial pressurization according to claim 5, characterized in that, During the cycle of steps 2 to 5, the sintering chamber (10) is kept in a high vacuum state and no vacuum breaking operation is performed. When the bar reaches the target length, the vacuum breaking operation is performed on the sintering chamber (10) to remove the bar.

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