Vacuum consumable furnace with complex magnetic field generator and melting method

Abstract

The application discloses a vacuum consumable furnace with a composite magnetic field generator and a smelting method, relates to the technical field of vacuum metallurgy, and comprises a furnace body, a water-cooled copper crucible is mounted on the inner wall of the furnace body, a water-cooled interlayer is formed between the inner wall of the furnace body and the surface of the water-cooled copper crucible, and a driving assembly is mounted on the inner wall of the water-cooled interlayer; the vacuum consumable furnace with the composite magnetic field generator and the smelting method are characterized in that a composite magnetic field generator composed of a limiting guide plate, a fixed sleeve ring, a first protective sleeve ring, a second protective sleeve ring, a direct-current coil, a pulse coil and the driving assembly is arranged in the water-cooled interlayer, the composite magnetic field generator composed of the direct-current coil and the pulse coil can move synchronously along the water-cooled copper crucible in the axial direction with the change of the liquid surface height of the molten pool, and therefore, the steady magnetic field and the pulse magnetic field can accurately act on the end of the consumable electrode and the metal molten pool area in the whole smelting process, and the partition dynamic composite magnetic control effect on the electric arc behavior and the solidification process of the molten pool is achieved.

Description

Technical Field

[0001] This invention relates to the field of vacuum metallurgy technology, specifically to a vacuum arc furnace with a composite magnetic field generator and a smelting method. Background Technology

[0002] In the field of vacuum metallurgy, the vacuum arc remelting furnace (ARF) plays an irreplaceable role as a key smelting device for preparing high-purity, high-performance metals and alloys. This technology utilizes the high temperature generated by an electric arc in a high-vacuum environment to melt the consumable electrode, achieving metal refining and purification, and is particularly suitable for smelting reactive and refractory metals. With the continuous advancement of materials science, more stringent requirements have been placed on the stability of the electric arc, the uniformity of the molten pool, and the microstructure control of the ingot during the smelting process. To meet these requirements, electromagnetic field control technology has been gradually introduced into the smelting process of the ARF, applying an external magnetic field to improve the arc morphology, optimize the molten pool flow, and thus enhance the smelting quality.

[0003] However, existing vacuum arc furnaces have shortcomings when introducing electromagnetic field control technology: the magnetic field generating devices are mostly fixed designs, which cannot adjust the position of the magnetic field in real time according to the dynamic changes of the molten pool level during the melting process. As a result, in the early stage of melting, the magnetic field can effectively act on the end of the arc-consuming electrode and the initial molten pool area, stabilizing the arc and promoting uniform mixing of the molten pool. However, as melting progresses, the arc-consuming electrode is continuously consumed, and the molten pool level gradually rises. The fixed magnetic field generating device can no longer accurately apply the magnetic field to the new molten pool area. The resulting problems include decreased arc stability, local overheating or excessive temperature gradients inside the molten pool, which leads to uneven solidification structure and seriously affects the metallurgical quality and overall performance of the ingot. Therefore, it is necessary to improve it. Summary of the Invention

[0004] The purpose of this invention is to provide a vacuum arc furnace with a composite magnetic field generator and a smelting method to solve the problem that in the prior art, the magnetic field generating device cannot adjust the position of the magnetic field in real time according to the dynamic changes of the molten pool surface during the smelting process, resulting in decreased arc stability and uneven solidification structure of the molten pool.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a vacuum self-consuming furnace with a composite magnetic field generator, comprising a furnace body, wherein a water-cooled copper crucible is installed on the inner wall of the furnace body, a water-cooled interlayer is formed between the inner wall of the furnace body and the surface of the water-cooled copper crucible, and a driving component is installed on the inner wall of the water-cooled interlayer.

[0006] A limiting guide plate is installed on the inner bottom wall of the water-cooled jacket. A sliding block is slidably connected to the inner wall of the limiting guide plate. A fixing collar is installed on the top of the sliding block. A first protective collar is installed on one side of the inner wall of the fixing collar, and a second protective collar is installed on the other side of the inner wall of the fixing collar. A DC coil is installed on the inner wall of the first protective collar, and a pulse coil is installed on the inner wall of the second protective collar. The fixing collar is connected to a driving assembly, which is used to drive the fixing collar to move axially along the fixing collar.

[0007] Furthermore, a protective box is installed on the inner wall of the water-cooled jacket, a drive mechanism is installed on the inner wall of the protective box, a drive rod is installed at the output end of the drive mechanism, a lead screw is installed at the front end of the drive rod, a threaded collar is threadedly connected to the surface of the lead screw, and the bottom of the threaded collar is installed on the upper surface of the fixed collar. The protective box, drive mechanism, drive rod and lead screw together form a drive assembly.

[0008] Furthermore, an injection pipe is installed at the top of the furnace body, and a discharge pipe is installed at the bottom of the furnace body, with one end of both the injection pipe and the discharge pipe inserted into the inner wall of the water-cooled jacket.

[0009] Furthermore, a fixed bracket is installed at the bottom of the furnace body, and an installation platform is installed on the surface of the furnace body.

[0010] Furthermore, a control component is mounted on top of the installation platform.

[0011] Furthermore, a protective cover is rotatably connected to one side of the furnace body, and a control panel is installed on the surface of the furnace body.

[0012] Furthermore, a vacuum unit is installed on one side of the furnace body, and a suction pipe is installed at the input end of the vacuum unit, with one end of the suction pipe inserted into the inner wall of the water-cooled jacket.

[0013] A smelting method in a vacuum arc furnace equipped with a composite magnetic field generator includes the following steps:

[0014] S1. Place the consumable electrode inside the furnace and use a vacuum unit to evacuate the inside of the furnace to a preset vacuum level.

[0015] S2. Circulating cooling water is introduced into the water-cooled jacket, and the cooling water circulation is maintained through the injection pipe and the discharge pipe.

[0016] S3. After arc initiation, control the drive mechanism to rotate the lead screw, causing the fixed collar to move axially along the limit guide plate to adjust the position of the DC coil and pulse coil in the crucible axial direction.

[0017] S4. A DC current is passed into the DC coil, and a pulse current or alternating current is passed into the pulse coil to form a composite magnetic field in the molten pool region, which is a superposition of a steady magnetic field and an alternating magnetic field.

[0018] S5. During the smelting process, the parameters of the smelting current, smelting voltage, smelting rate, and the composite magnetic field are adjusted by the control components.

[0019] Furthermore, the parameters of the composite magnetic field include the amplitude of the DC current, the amplitude of the pulse current or alternating current, the frequency, and the commutation period.

[0020] Compared with the prior art, the present invention provides a vacuum consumable furnace with a composite magnetic field generator and a melting method. By setting a limiting guide plate, a fixing collar, a first protective collar, a second protective collar, a DC coil, a pulse coil and a driving component in the water-cooled jacket, the composite magnetic field generator composed of the DC coil and the pulse coil can move synchronously along the axial direction of the water-cooled copper crucible with the change of the liquid level in the molten pool. Thus, the constant magnetic field and the pulse magnetic field always act precisely on the end of the consumable electrode and the molten pool area throughout the melting process, achieving a zoned dynamic composite magnetic control effect on the arc behavior and the solidification process of the molten pool.

[0021] By constructing a circulating cooling loop in the water-cooled jacket using injection and discharge pipes, and integrating the equipment support and operation platform architecture consisting of fixed brackets and installation platforms, along with the control components, vacuum unit, and suction pipe, the system achieves precise temperature control of the cooling system, reliable maintenance of the high vacuum environment inside the furnace, and automated closed-loop control of the entire smelting process, based on the active regulation function of the composite magnetic field. This results in a comprehensive improvement in the precise regulation of smelting process parameters and the stability of equipment operation.

[0022] By introducing a composite magnetic field formed by the superposition of DC coil and pulse coil in the melting process, and dynamically adjusting the axial position of the fixing ring and the DC coil and pulse coil it carries according to the change of the molten pool height, a stable magnetic field and an alternating magnetic field with precise position matching are applied simultaneously during the melting of the consumable electrode and the solidification of the molten pool, thereby achieving a synergistic and active control effect on the arc stability and the solidification structure of the molten pool. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the vacuum unit structure provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of a water-cooled copper crucible provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of a water-cooled sandwich structure provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the lead screw structure provided in an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of a DC coil structure provided in an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of a pulse coil structure provided in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Furnace body; 2. Water-cooled copper crucible; 3. Water-cooled jacket; 4. Limiting guide plate; 5. Sliding block; 6. Fixing collar; 7. First protective collar; 8. Second protective collar; 9. DC coil; 10. Pulse coil; 11. Protective box; 12. Drive mechanism; 13. Drive rod; 14. Lead screw; 15. Threaded collar; 16. Injection pipe; 17. Discharge pipe; 18. Fixing bracket; 19. Mounting platform; 20. Control components; 21. Protective cover; 22. Control panel; 23. Vacuum unit; 24. Suction pipe. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] As attached Figure 1 To be continued Figure 7 As shown:

[0035] Example 1:

[0036] The present invention provides a vacuum self-consuming furnace with a composite magnetic field generator, including a furnace body 1, a water-cooled copper crucible 2 installed on the inner wall of the furnace body 1, a water-cooled jacket 3 formed between the inner wall of the furnace body 1 and the surface of the water-cooled copper crucible 2, and a driving component installed on the inner wall of the water-cooled jacket 3.

[0037] A limiting guide plate 4 is installed on the inner bottom wall of the water-cooled jacket 3. A sliding block 5 is slidably connected to the inner wall of the limiting guide plate 4. A fixing collar 6 is installed on the top of the sliding block 5. A first protective collar 7 is installed on one side of the inner wall of the fixing collar 6, and a second protective collar 8 is installed on the other side of the inner wall of the fixing collar 6. A DC coil 9 is installed on the inner wall of the first protective collar 7, and a pulse coil 10 is installed on the inner wall of the second protective collar 8. The fixing collar 6 is connected to the drive assembly, which is used to drive the fixing collar 6 to move axially along the fixing collar 6. A protective box 11 is installed on the inner wall of the water-cooled jacket 3. A drive mechanism 12 is installed on the inner wall of the protective box 11. A drive rod 13 is installed at the output end of the drive mechanism 12. A lead screw 14 is installed at the front end of the drive rod 13. A threaded collar 15 is threadedly connected to the surface of the lead screw 14, and the bottom of the threaded collar 15 is installed on the upper surface of the fixing collar 6. The protective box 11, the drive mechanism 12, the drive rod 13, and the lead screw 14 together form the drive assembly.

[0038] In use, the furnace body 1, as the outermost vacuum-sealed shell, provides a high-vacuum environment isolated from the atmosphere for the entire smelting process. A water-cooled copper crucible 2, made of high thermal conductivity copper, is installed on its inner wall. This crucible 2 is filled with forced-circulation cooling water to directly contain the molten metal pool formed by the melting of the consumable electrode. Forced cooling of its inner wall enables sequential directional solidification of the molten metal. A ring-shaped cavity structure, namely a water-cooled jacket 3, is formed between the inner wall of the furnace body 1 and the outer surface of the water-cooled copper crucible 2. This water-cooled jacket 3 serves as a circulation channel for the cooling water to continuously remove heat from the crucible wall, and also provides physical space for the installation and operation of the composite magnetic field generator and its drive components. A limiting guide plate 4 is fixedly installed on the inner bottom wall of the water-cooled jacket 3. This limiting guide plate 4 extends along the crucible axis and has a guide groove on its inner wall. A sliding block 5 is slidably embedded into the groove on the inner wall of the limiting guide plate 4, thus forming a set of axial linear guide pairs. The top of the sliding block 5 is fixed... A fixed collar 6 is fixedly connected to the water-cooled copper crucible 2. The fixed collar 6 is a ring structure that surrounds the periphery of the water-cooled copper crucible 2 and serves as the direct support base for the magnetic field coil. It moves along the crucible axis together with the sliding block 5. A first protective collar 7 is fixedly installed on one side of the inner wall of the fixed collar 6. A DC coil 9 is embedded and fixed in the first protective collar 7. The DC coil 9 is made of multi-turn insulated wire. After a DC current is applied, it can generate a stable axial magnetic field with adjustable intensity in the molten pool area inside the crucible. This magnetic field is used to constrain the radial movement of charged particles in the arc plasma, suppress magnetic blow, and improve the stability of arc combustion. A second protective collar 8 is fixedly installed on the other side of the inner wall of the fixed collar 6. A pulse coil 10 is embedded and fixed in the second protective collar 8. The pulse coil 10 is made of conductor that can withstand high-frequency pulse current. After a pulse current or alternating current is applied, an alternating Lorentz force is induced inside the molten pool, thereby electromagnetically stirring the molten metal pool to break dendrites, refine the solidification structure, and reduce macroscopic segregation.To enable precise position control of the composite magnetic field generator composed of the DC coil 9 and the pulse coil 10 along the crucible axis, a protective box 11 is installed on the inner wall of the water-cooled jacket 3. This protective box 11 is a sealed shell structure used to isolate the internal drive mechanism 12 from the cooling water medium in the water-cooled jacket 3. The drive mechanism 12 is fixedly installed on the inner wall of the protective box 11. Specifically, the drive mechanism 12 can be a servo motor or a stepper motor. Its output end is connected to a drive rod 13 via a coupling. A lead screw 14 is coaxially fixed to the front end of the drive rod 13. A threaded collar 15 is threaded onto the surface of the lead screw 14, and the bottom of the threaded collar 15 is fixedly connected to the upper surface of the fixed collar 6 via a connector, thereby preventing… The protective box 11, drive mechanism 12, drive rod 13, and lead screw 14 together form a linear drive assembly. When the drive mechanism 12 drives the lead screw 14 to rotate, the threaded collar 15 converts the rotational motion into linear displacement along the axis of the lead screw 14, thereby driving the fixed collar 6 and its carried DC coil 9 and pulse coil 10 to move smoothly along the direction of the limiting guide plate 4. This allows for dynamic adjustment of the magnetic field application position according to the actual height of the molten pool during the melting process, ensuring that the constant magnetic field and pulsed magnetic field always act precisely on the end of the consumable electrode and the molten pool area. This achieves active, zoned, and dynamic composite magnetic control of the arc behavior and molten pool solidification behavior during vacuum consumable melting, thereby improving the metallurgical quality and microstructure uniformity of the ingot.

[0039] Example 2:

[0040] This embodiment is basically the same as the previous embodiment, except that an injection pipe 16 is installed on the top of the furnace body 1, and a discharge pipe 17 is installed on the bottom of the furnace body 1. One end of both the injection pipe 16 and the discharge pipe 17 is inserted into the inner wall of the water-cooled jacket 3. A fixed bracket 18 is installed on the bottom of the furnace body 1. An installation platform 19 is installed on the surface of the furnace body 1. A control component 20 is installed on the top of the installation platform 19. A protective cover 21 is rotatably connected to one side of the furnace body 1. A control panel 22 is installed on the surface of the furnace body 1. A vacuum unit 23 is installed on one side of the furnace body 1. A suction pipe 24 is installed at the input end of the vacuum unit 23, and one end of the suction pipe 24 is inserted into the inner wall of the water-cooled jacket 3.

[0041] In use, an injection pipe 16 is installed on the top of the furnace body 1. One end of the injection pipe 16 is connected to an external cooling water source, and the other end is inserted into the upper part of the inner wall of the water-cooled jacket 3. This is used to continuously introduce low-temperature circulating cooling water into the water-cooled jacket 3 to force convection cooling of the outer wall of the water-cooled copper crucible 2. A discharge pipe 17 is installed at the bottom of the furnace body 1. One end of the discharge pipe 17 is also inserted into the bottom of the inner wall of the water-cooled jacket 3, and the other end leads to an external return water pipe. This is used to discharge the cooling water after heat absorption and heating in a timely manner to maintain the heat exchange efficiency of the cooling system. The injection pipe 16 and the discharge pipe 17 together constitute the cooling medium circulation loop of the water-cooled jacket 3. To ensure the crucible wall temperature remains within the safe process range, a fixed support 18 is fixedly installed at the bottom of the furnace body 1. This fixed support 18 is a rigid steel structure used to stably support the entire vacuum self-consuming furnace equipment on the installation foundation, while bearing the weight of the furnace body and the thermal stress and electromagnetic force load generated during the melting process. An installation platform 19 is installed on the surface of the furnace body 1. The installation platform 19 is a horizontal working platform structure for operators to stand on when performing equipment inspection, maintenance and process operations. A control component 20 is fixedly installed on the top of the installation platform 19. The control component 20 integrates a programmable logic controller (PLC) and an industrial computer. The power management module and signal conditioning circuit are used for closed-loop acquisition, logic operation, and real-time control of key process variables such as melting current, melting voltage, melting rate, magnetic field parameters, and vacuum degree. A protective cover 21 is hinged to one side of the furnace body 1. When closed, the cover forms a sealed fit with the furnace body 1, isolating the external environment from the high vacuum area inside the furnace during the melting process. When open, it facilitates the operator's assembly, disassembly, cleaning, and maintenance of the water-cooled copper crucible 2, consumable electrodes, and coil assemblies inside the furnace. A control panel 22 is installed on the surface of the furnace body 1. The control panel 22 is a human-machine interface equipped with a touch screen. An emergency stop button and status indicator lights are used to visually display equipment operating parameters, alarm information, and smelting process curves to the operator, and to receive operating commands to achieve remote monitoring and intervention of the smelting process. A vacuum unit 23 is installed on one side of the furnace body 1. The vacuum unit 23 consists of a mechanical rotary vane pump, a Roots booster pump, and an oil diffusion pump or molecular pump connected in series. Its input end is connected to a suction pipe 24 through a flange. The other end of the suction pipe 24 is inserted into the vacuum chamber area isolated from the water-cooled jacket 3 on the inner wall of the furnace body 1. After the vacuum unit 23 is started, it continuously removes gas molecules from the furnace chamber through the suction pipe 24, reducing the vacuum level in the furnace to below 6.67 × 10⁻⁶. -2Pascal's ultimate vacuum state effectively prevents oxidation of high-temperature molten metal and promotes the escape of dissolved gases and volatile impurities. The device constructs a complete vacuum arc furnace system with active control capability of composite magnetic field, precise cooling and temperature control function, and high vacuum environment guarantee. Ultimately, it achieves comprehensive and precise control over arc behavior, molten pool flow and solidification structure during metal smelting, significantly improving the density, compositional uniformity and comprehensive mechanical properties of the ingot.

[0042] Example 3:

[0043] A smelting method in a vacuum arc furnace equipped with a composite magnetic field generator includes the following steps:

[0044] S1. Place the consumable electrode inside the furnace body 1, and use the vacuum unit 23 to evacuate the inside of the furnace body 1 to a preset vacuum level.

[0045] S2. Circulating cooling water is introduced into the water-cooled jacket 3, and the cooling water circulation is maintained through the injection pipe 16 and the discharge pipe 17.

[0046] S3. After the arc is started, the control drive mechanism 12 drives the lead screw 14 to rotate, so that the fixed collar 6 moves axially along the limiting guide plate 4 to adjust the position of the DC coil 9 and the pulse coil 10 in the crucible axial direction.

[0047] S4. A DC current is passed into the DC coil 9, and a pulse current or alternating current is passed into the pulse coil 10 to form a composite magnetic field in the molten pool region, which is a superposition of a steady magnetic field and an alternating magnetic field.

[0048] S5. During the smelting process, the parameters of smelting current, smelting voltage, smelting rate and composite magnetic field are adjusted by the control component 20.

[0049] The parameters of the composite magnetic field include the amplitude of the DC current, the amplitude, frequency, and commutation period of the pulse current or alternating current.

[0050] Application example:

[0051] This paper addresses a vacuum arc remelting (ACR) production scenario for large-size titanium alloy ingots. In this scenario, traditional vacuum ACR furnaces suffer from several issues during the melting process, including uneven energy distribution due to arc magnetic blow, coarse solidification in the molten pool, and significant compositional segregation at the ingot head and bottom. Therefore, it is crucial to introduce an actively controllable composite magnetic field device to simultaneously achieve the dual metallurgical effects of arc stabilization and electromagnetic stirring of the molten pool, thereby improving the internal quality of the ingot and increasing the material yield. This application example utilizes the aforementioned vacuum ACR furnace equipped with a composite magnetic field generator for the melting operation. The specific application process is as follows.

[0052] First, the titanium alloy consumable electrode, which has been pressed and welded, is clamped by an electrode rod and suspended at the central axis position inside the furnace body 1, ensuring that the consumable electrode and the inner wall of the water-cooled copper crucible 2 maintain a uniform annular gap. Then, the protective cover 21 on the side of the furnace body 1 is closed to seal it tightly against the furnace body 1. Subsequently, the vacuum unit 23 is started, and the internal chamber of the furnace body 1 is continuously evacuated through the suction pipe 24 until the vacuum degree inside the furnace reaches the preset process range, so as to remove residual gas inside the furnace and prevent the metal from oxidizing or absorbing gas during the high-temperature melting process.

[0053] After the vacuum level is reached, low-temperature circulating cooling water is introduced into the water-cooled jacket 3, which is located between the inner wall of the furnace body 1 and the outer surface of the water-cooled copper crucible 2, through the injection pipe 16. After entering the upper cavity of the water-cooled jacket 3 through the injection pipe 16, the cooling water flows downward along the annular channel and fully contacts the outer wall of the water-cooled copper crucible 2 to remove heat. After absorbing heat and heating up, the cooling water returns to the external cooling system through the bottom discharge pipe 17 for cooling and recirculation. In this way, forced cooling boundary conditions are established on the inner wall of the water-cooled copper crucible 2, providing a stable temperature gradient for the subsequent sequential directional solidification of the molten metal pool.

[0054] Subsequently, the melting power supply is activated, and a DC arc is ignited between the bottom of the consumable electrode and the arc-starting material at the bottom of the water-cooled copper crucible 2. The high temperature of the arc causes the end of the consumable electrode to gradually melt and form metal droplets. The droplets pass through the arc area and fall into the bottom of the water-cooled copper crucible 2, where they converge to form an initial molten pool. At the same time, the control component 20 sends motion commands to the drive mechanism 12 according to the preset melting process curve. The drive mechanism 12 outputs rotational power, which is transmitted to the lead screw 14 via the drive rod 13. When the lead screw 14 rotates, it drives the threaded collar 15 to generate linear displacement along the axis of the lead screw 14 through the threaded engagement. Since the bottom of the threaded collar 15 is fixed to the upper surface of the fixed collar 6, the fixed collar 6 moves smoothly along the axis of the water-cooled copper crucible 2 under the guidance and constraint of the sliding block 5 and the limiting guide plate 4. This drives the DC coil 9 embedded in the first protective collar 7 on the inner wall of the fixed collar 6 and the pulse coil 10 embedded in the second protective collar 8 on the inner wall of the fixed collar 6 to be synchronously adjusted to the preset axial height position corresponding to the liquid level of the initial molten pool.

[0055] After the melting process enters a steady-state stage, the control component 20 outputs an adjustable DC current to the DC coil 9. After the DC current is applied to the DC coil 9, a steady magnetic field is generated in the molten pool region inside the water-cooled copper crucible 2. The direction of the magnetic field is consistent with the axis of the consumable electrode or at a set angle. This steady magnetic field acts on the charged particles in the arc plasma, restricting their radial diffusion motion, thereby effectively suppressing the magnetic blow phenomenon of the arc and concentrating the arc energy in the central region of the consumable electrode and uniformly transferring heat to the molten pool. At the same time, the control component 20 outputs a pulse current or alternating current to the pulse coil 10. The alternating magnetic field generated by the pulse coil 10 induces an alternating Lorentz force in the conductive molten metal of the molten pool. This Lorentz force drives the periodic forced convection motion inside the molten pool, applies a shearing action to the dendrites growing at the solidification front to promote their breakage and release, and promotes the uniform mixing and distribution of alloying elements in the molten pool.

[0056] Throughout the smelting process, the control component 20 continuously receives real-time signals from the weighing sensor, voltage and current transformer, and vacuum gauge. Based on these signals, it dynamically adjusts the smelting current, smelting voltage, and consumable electrode feed rate to maintain the stability of the arc length. Simultaneously, as the consumable electrode is continuously consumed and the molten pool level gradually rises, the control component 20 controls the drive mechanism 12 to drive the lead screw 14 to rotate. This causes the fixed collar 6 and its carried DC coil 9 and pulse coil 10 to move synchronously upwards along the limiting guide plate 4 with the molten pool level. This ensures that the composite magnetic field formed by the superposition of the constant magnetic field and the alternating magnetic field always accurately covers the end of the consumable electrode and the molten metal pool area, avoiding the attenuation of the control effect due to deviation of the magnetic field's position.

[0057] When the consumable electrode is consumed to the preset remaining length, the control component 20 gradually reduces the melting current and adjusts the composite magnetic field parameters according to the hot capping process curve to slow down the melting rate and improve the feeding conditions at the top of the ingot. After the electric arc is extinguished, the vacuum environment inside the furnace is maintained and the cooling water is kept circulating so that the ingot can be fully cooled and solidified from top to bottom in the water-cooled copper crucible 2. Then the protective cover 21 is opened and the finished ingot is demolded and taken out from the bottom of the water-cooled copper crucible 2, thus completing the entire vacuum consumable melting process with composite magnetic field control.

[0058] Working principle: During the operation of the vacuum consumable furnace equipped with a composite magnetic field generator, the consumable electrode is first clamped inside the furnace body 1 and suspended on the central axis of the water-cooled copper crucible 2 by the electrode rod. The protective cover 21 is closed to form a sealed cavity in the furnace body 1. Then, the vacuum unit 23 is started and the gas molecules inside the furnace body 1 are continuously removed through the suction pipe 24 until the vacuum degree inside the furnace reaches the preset process requirements, so as to remove residual gas and prevent the metal from oxidizing or absorbing gas during high-temperature melting. At the same time, external circulating cooling water enters the upper cavity of the water-cooled jacket 3, which is opened between the inner wall of the furnace body 1 and the outer surface of the water-cooled copper crucible 2, through the injection pipe 16 at the top of the furnace body 1. The cooling water flows downward along the annular jacket. During the process, forced convection heat transfer occurs close to the outer wall of the water-cooled copper crucible 2, carrying away the heat absorbed by the molten pool from the crucible wall. The cooling water, after absorbing heat and heating up, flows back from the bottom outlet pipe 17 of the furnace body 1 to the external cooling system for cooling and recirculation. This establishes a stable forced cooling boundary on the inner wall of the water-cooled copper crucible 2 to ensure the sequential and directional solidification of the subsequent molten metal. During the arc ignition stage, the control component 20 sends a command to the main power supply of the smelting process to ignite a DC arc between the bottom of the consumable electrode and the arc-igniting material at the bottom of the water-cooled copper crucible 2. The high temperature of the arc causes the end of the consumable electrode to continuously melt, forming molten metal droplets that fall into the bottom of the water-cooled copper crucible 2 and converge into a molten pool. At the same time, the control component 20 sends a command to the drive mechanism 12 installed inside the protective box 11. Upon receiving a motion command, the drive mechanism 12 drives the lead screw 14 to rotate via the drive rod 13. The threaded engagement between the lead screw 14 and the threaded collar 15 converts the rotational motion into linear displacement of the threaded collar 15 along the axis of the lead screw 14. Since the bottom of the threaded collar 15 is fixedly connected to the upper surface of the fixed collar 6, and the fixed collar 6 slides with the limiting guide plate 4 fixed to the bottom wall of the water-cooled jacket 3 via its bottom sliding block 5, the fixed collar 6 carries the DC coil 9 embedded in the first protective collar 7 on one side of its inner wall and the pulse coil 10 embedded in the second protective collar 8 on the other side of its inner wall, smoothly moving along the axis of the water-cooled copper crucible 2 to a preset height position corresponding to the initial molten pool surface; entering the steady-state melting stage. After the first stage, the control component 20 outputs a DC current to the DC coil 9. After the DC coil 9 is energized, an axial steady magnetic field is generated in the molten pool region inside the crucible. This steady magnetic field exerts a constraint on the radial motion of charged particles in the arc plasma to suppress the magnetic blow phenomenon, thereby concentrating the arc energy evenly on the end of the consumable electrode. At the same time, the control component 20 outputs a pulse current or alternating current to the pulse coil 10. The alternating magnetic field generated by the pulse coil 10 induces an alternating Lorentz force inside the conductive metal molten pool. This Lorentz force drives the melt in the molten pool to generate periodic forced convection and oscillation, exerts a mechanical breaking effect on the dendritic structure at the solidification front, and promotes the uniform mixing of solute elements in the molten pool.As the consumable electrode continuously melts and is consumed, the molten pool level gradually rises. The control component 20 dynamically controls the drive mechanism 12 to rotate the lead screw 14 based on real-time monitored melting parameters. This, in turn, drives the fixed collar 6 and its supported DC coil 9 and pulse coil 10 to move synchronously upwards along the limiting guide plate 4 with the molten pool level via the threaded collar 15. This ensures that the composite magnetic field formed by the superposition of the constant magnetic field and the alternating magnetic field always accurately covers the end of the consumable electrode and the molten pool area, achieving full-process active composite magnetic control of the arc behavior and the molten pool solidification process. Throughout the entire melting process… The fixed bracket 18 securely supports the furnace body 1 and the mounting platform 19 on the foundation. The operator inputs process commands through the control panel 22 and monitors in real time the operating data collected by the control component 20, including melting current, melting voltage, melting rate, magnetic field parameters, and vacuum degree. Finally, after the consumable electrode has been consumed to a predetermined length, the melting power is gradually reduced and the composite magnetic field parameters are adjusted according to the preset hot-sealing program to complete the feeding control of the ingot top. After the ingot has fully cooled and solidified in the water-cooled copper crucible 2, the protective cover 21 is opened to demold the finished ingot.

[0059] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A vacuum arc furnace with a composite magnetic field generator, comprising a furnace body (1), characterized in that, A water-cooled copper crucible (2) is installed on the inner wall of the furnace body (1), and a water-cooled interlayer (3) is formed between the inner wall of the furnace body (1) and the surface of the water-cooled copper crucible (2). A drive assembly is installed on the inner wall of the water-cooled interlayer (3). The inner bottom wall of the water-cooled jacket (3) is equipped with a limiting guide plate (4), and a sliding block (5) is slidably connected to the inner wall of the limiting guide plate (4). A fixing collar (6) is installed on the top of the sliding block (5). A first protective collar (7) is installed on one side of the inner wall of the fixing collar (6), and a second protective collar (8) is installed on the other side of the inner wall of the fixing collar (6). A DC coil (9) is installed on the inner wall of the first protective collar (7), and a pulse coil (10) is installed on the inner wall of the second protective collar (8). The fixing collar (6) is connected to a driving assembly, which is used to drive the fixing collar (6) to move axially along the fixing collar (6).

2. A vacuum arc furnace with a composite magnetic field generator according to claim 1, characterized in that, The inner wall of the water-cooled jacket (3) is equipped with a protective box (11), the inner wall of the protective box (11) is equipped with a drive mechanism (12), the output end of the drive mechanism (12) is equipped with a drive rod (13), the front end of the drive rod (13) is equipped with a lead screw (14), the surface of the lead screw (14) is threaded with a threaded collar (15), and the bottom of the threaded collar (15) is installed on the upper surface of the fixed collar (6). The protective box (11), drive mechanism (12), drive rod (13) and lead screw (14) together form a drive assembly.

3. A vacuum arc furnace with a composite magnetic field generator according to claim 1, characterized in that, An injection pipe (16) is installed on the top of the furnace body (1), and a discharge pipe (17) is installed on the bottom of the furnace body (1). One end of both the injection pipe (16) and the discharge pipe (17) is inserted into the inner wall of the water-cooled jacket (3).

4. A vacuum arc furnace with a composite magnetic field generator according to claim 1, characterized in that, A fixed bracket (18) is installed at the bottom of the furnace body (1), and an installation platform (19) is installed on the surface of the furnace body (1).

5. A vacuum arc furnace with a composite magnetic field generator according to claim 4, characterized in that, The control component (20) is mounted on the top of the mounting platform (19).

6. A vacuum arc furnace with a composite magnetic field generator according to claim 1, characterized in that, A protective cover (21) is rotatably connected to one side of the furnace body (1), and a control panel (22) is installed on the surface of the furnace body (1).

7. A vacuum arc furnace with a composite magnetic field generator according to claim 1, characterized in that, A vacuum unit (23) is installed on one side of the furnace body (1). A suction pipe (24) is installed at the input end of the vacuum unit (23), and one end of the suction pipe (24) is inserted into the inner wall of the water-cooled jacket (3).

8. A smelting method for a vacuum arc furnace equipped with a composite magnetic field generator, applicable to the vacuum arc furnace equipped with a composite magnetic field generator as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Place the consumable electrode inside the furnace body (1) and use the vacuum unit (23) to evacuate the inside of the furnace body (1) to the preset vacuum level. S2. Circulating cooling water is introduced into the water-cooled jacket (3), and the cooling water circulation is maintained through the injection pipe (16) and the discharge pipe (17); S3. After the arc is started, the control drive mechanism (12) drives the lead screw (14) to rotate, so that the fixed collar (6) moves axially along the limit guide plate (4) to adjust the position of the DC coil (9) and the pulse coil (10) in the crucible axial direction. S4. A DC current is passed into the DC coil (9), and a pulse current or alternating current is passed into the pulse coil (10) to form a composite magnetic field in the molten pool region, which is a superposition of a steady magnetic field and an alternating magnetic field. S5. During the smelting process, the parameters of the smelting current, smelting voltage, smelting rate and the composite magnetic field are adjusted by the control component (20).

9. A smelting method for a vacuum arc furnace with a composite magnetic field generator according to claim 8, characterized in that, The parameters of the composite magnetic field include the amplitude of the DC current, the amplitude of the pulse current or alternating current, the frequency, and the commutation period.

Images