Large-specification suspension smelting device

Abstract

The invention relates to a large-specification suspension smelting device which comprises a vacuum furnace chamber, a crucible and a coil, the crucible and the coil are arranged in the furnace chamber, the coil comprises an upper coil and a lower coil which are wound on the outer side of the crucible, and the upper coil and the lower coil are connected with a power source arranged outside the furnace chamber. The frequency generated by the lower coil is higher than that generated by the upper coil. The double induction coils which are composed of the upper coil and the lower coil, are powered by the power source and work at different frequencies are adopted, so that the lower coil can generate enough suspension force and heating intensity through the high frequency to smelt refractory metal and support a molten pool; and the upper coil ensures that the magnetic field effectively penetrates through and heats the central area of the large-specification crucible through lower frequency, so that the double bottlenecks of insufficient heating temperature and weakened suspension force under single low frequency are cooperatively solved.

Description

Technical Field

[0001] This invention relates to the field of suspension melting technology, and in particular to a large-scale suspension melting apparatus. Background Technology

[0002] Suspension melting is a special metallurgical process that uses a high-frequency electromagnetic field generated by an induction coil to melt and solidify metallic materials in a suspended state. Currently, conventional suspension melting technology is mainly used for the preparation of smaller-sized materials. However, with the increasing demand for large-scale, integrated, high-performance metal components in aerospace, energy, and high-end equipment manufacturing, the development of large-scale (typically referring to crucible diameters greater than 250mm) suspension melting technology has become an inevitable trend. However, a key technical bottleneck has been encountered in the process of expanding this technology to larger sizes. Considering the depth of electromagnetic field penetration, to accommodate the melting of larger volumes of material within large crucibles, a lower frequency power supply is required, typically operating at a frequency below 5kHz.

[0003] However, using lower frequencies presents several problems. First, excessively low frequencies weaken the skin effect of the electromagnetic field, making it difficult for eddy current heat to penetrate to the center of the material, resulting in insufficient heating efficiency and temperature, severely affecting material uniformity. Second, lower frequencies directly weaken the electromagnetic levitation force, which cannot effectively support large-mass molten pools, leading to an increased contact area between the molten pool and the bottom of the crucible, and a thicker, heavier solidified shell. Therefore, there is an urgent need for a device that can overcome the aforementioned frequency and specification limitations to achieve efficient, uniform heating and stable levitation melting of large-sized materials. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a large-scale suspension melting apparatus.

[0005] The technical solution is as follows: A large-scale suspension melting device includes a vacuum furnace chamber and a crucible and a coil disposed inside the furnace chamber. The coil includes an upper coil and a lower coil wound around the outside of the crucible. The upper coil and the lower coil are respectively connected to a power source disposed outside the furnace chamber. The lower coil is configured such that the frequency generated by the lower coil is higher than the frequency generated by the upper coil.

[0006] As an improvement to the above scheme, the upper coil uses a frequency of 3-5kHz and the lower coil uses a frequency of 10-15kHz.

[0007] As an improvement to the above solution, the upper coil and the lower coil have the same inner diameter, and both are cylindrical structures.

[0008] As an improvement to the above solution, a Faraday ring is provided between the upper coil and the lower coil. The Faraday ring has the same inner diameter as the coil and is fixed to the upper and lower coils as a whole by an insulating component.

[0009] As an improvement to the above solution, the Faraday ring is made of copper and is equipped with a separate circulating cooling water channel.

[0010] As an improvement to the above scheme, the upper coil and the lower coil share a single rotatable electrode spindle for power supply, and the spindle has two output terminals that are respectively connected to the two sets of coils.

[0011] As an improvement to the above scheme, the upper coil and the lower coil have the same number of turns.

[0012] As an improvement to the above scheme, the upper coil and the lower coil have different numbers of turns.

[0013] As an improvement to the above scheme, the pitch of the Faraday ring is equal to the pitch of the upper coil and / or the lower coil.

[0014] Compared with the prior art, the present invention has the following advantages: 1. This invention employs a dual induction coil consisting of an upper coil and a lower coil, each powered by a power source and operating at different frequencies. This allows the lower coil to generate sufficient levitation force and heating intensity at a higher frequency to melt refractory metals and support the molten pool, while the upper coil ensures effective penetration and heating of the magnetic field into the central region of a large-sized crucible at a lower frequency. This collaboratively solves the dual bottlenecks of insufficient heating temperature and weakened levitation force at a single low frequency.

[0015] 2. By configuring the upper coil frequency to 3-5kHz and the lower coil frequency to 10-15kHz, this invention provides a clear frequency optimization range for the upper and lower sections. The low frequency ensures deep heating capability, while the high frequency provides the energy density necessary for melting start-up and levitation, thus making the effect of frequency division design concrete and optimized.

[0016] 3. This invention connects the upper and lower coils to the same rotatable electrode spindle for power supply, allowing the spindle to be directly driven to rotate after melting to achieve molten liquid tilting and casting. This efficiently integrates the melting and forming processes, simplifies the equipment structure, and improves the degree of process automation.

[0017] 4. By setting a Faraday ring between the upper and lower coils, the present invention effectively constrains and attenuates the mutual inductance interference between the two sets of coils with different frequencies by using the reverse magnetic field generated by its closed eddy current path, ensuring the independence and stability of their respective electromagnetic fields, thereby ensuring the precise controllability of frequency division heating and levitation effects.

[0018] 5. By using copper to manufacture the Faraday ring and configuring it with an independent circulating cooling water circuit, the present invention can promptly remove the heat generated by induction, prevent the ring from overheating and deforming or affecting the temperature field inside the furnace, and ensure the long-term reliable operation and lifespan of the magnetic shielding structure.

[0019] 6. This invention uses a column made of insulating material and a matching stud structure to fix the upper and lower coils and Faraday rings. While achieving overall mechanical fastening of the coil assembly, it also ensures reliable electrical insulation between the coils. The structure is simple and easy to maintain. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure 2 A cross-sectional view showing a Faraday ring disposed between the upper and lower coils of the present invention.

[0022] Figure 3 This is a schematic diagram of the Faraday ring and the configuration of the circulating cooling water circuit of the present invention.

[0023] Figure 4 This is a cross-sectional view of the Faraday ring of the present invention.

[0024] The meanings of the labels in the attached diagram are as follows: 1: furnace chamber, 2: crucible, 3: upper coil, 4: lower coil, 5: Faraday ring, 6: power supply, 61, 62: output terminals, a: water inlet, b: water outlet. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, this invention provides a large-scale suspension melting apparatus, comprising a vacuum furnace chamber 1, a crucible 2 disposed inside the vacuum furnace chamber 1, and an induction coil system. The induction coil system is coaxially sleeved on the outside of the crucible 2 and electrically connected to a power supply 6 located outside the furnace chamber 1. The furnace chamber 1 is filled with an argon protective atmosphere, which can effectively prevent oxidation of the material and gas inclusions during the melting process. The induction coil of this invention adopts an upper and lower dual-coil frequency division design, supplemented by a Faraday ring isolation structure.

[0027] Specifically, the induction coil consists of an upper coil 3 and a lower coil 4 arranged axially separated. The upper coil 3 and lower coil 4 have the same inner diameter and are both cylindrical structures, tightly wrapped around the periphery of the crucible 2. The power supply 6 has two independent output terminals 61 and 62, respectively connected to the upper coil 3 and the lower coil 4, and is capable of providing alternating current of different frequencies to the two sets of coils. Further configured, the operating frequency of the lower coil 4 is set to be higher than the operating frequency of the upper coil 3. In a preferred embodiment, the upper coil 3 uses a relatively low frequency of 3-5 kHz, while the lower coil 4 uses a relatively high frequency of 10-15 kHz. The purpose of this frequency division design is as follows: the lower coil 4 generates a strong electromagnetic field through high-frequency current, with a significant skin effect, which can generate dense eddy currents in the material at the bottom of the crucible 2, thereby providing strong local heating capacity and sufficient electromagnetic levitation force to melt refractory metals and effectively support the molten pool; while the upper coil 3 generates an electromagnetic field with greater penetration depth through low-frequency current, which can effectively heat the material in the central area of ​​the large-diameter crucible 2, solving the problem of insufficient heating in the central area under single low frequency. The number of turns of the upper coil 3 and the lower coil 4 can be the same or different according to the specific crucible size and material properties to achieve the optimal distribution of the electromagnetic field. The two sets of coils can work simultaneously, with the power supply 6 distributing their respective power in a proportional control mode, or they can work independently and in stages according to process needs, both of which can exert the maximum output capacity of the power supply, thereby efficiently breaking through the power limitations of large-scale levitation melting.

[0028] It should be further noted that, in order to power both sets of coils and achieve processing flexibility, this invention employs an integrated power supply structure. (Continue to refer to...) Figure 1 The upper coil 3 and the lower coil 4 are connected to the power supply via a rotatable electrode spindle. This spindle has two output terminals 61 and 62, which are connected to the two sets of coils respectively. This structure not only simplifies the power supply structure within the vacuum chamber, but more importantly, by driving the electrode spindle to rotate, it can tilt the entire coil and the internal crucible 2 together, thereby achieving the casting and molding of molten metal, greatly improving the process integration and operability of the equipment.

[0029] The inventors discovered in actual experiments that, due to the different operating frequencies and close proximity of the upper coil 3 and lower coil 4, the alternating magnetic fields they generate interfere with each other, affecting heating efficiency and levitation stability. Therefore, this invention incorporates a Faraday ring 5 within the axial gap between the upper coil 3 and lower coil 4. Figure 1 and Figure 2As shown, in a preferred embodiment, the Faraday ring 5 can be configured to have the same inner diameter as the upper coil 3 and the lower coil 4, and is fixed to the upper and lower coils as a single unit by an insulating component (not shown separately in the figure). The Faraday ring 5 is essentially a closed conductive ring, and its core function is based on the principle of magnetic circuit constraint in electromagnetic induction: when the leakage flux of any coil passes through the Faraday ring, eddy currents are induced in the ring. The magnetic field generated by these eddy currents is opposite in direction to the original leakage magnetic field, thereby confining most of the interfering magnetic field within the ring or closing its path, significantly weakening the mutual inductance coupling between the upper and lower coils. Experimental results show that this design can reduce the mutual inductance coefficient between the two sets of coils by 60% to 90%, ensuring the independence and operational stability of their respective frequency magnetic fields.

[0030] like Figure 3 and Figure 4 As shown, the Faraday ring 5 is made of copper tubing to provide excellent electrical and thermal conductivity. The specific manufacturing method is as follows: a standard cross-sectional copper tube is wound around a full circle to form an open ring. Then, a copper plate approximately 3mm thick with the same cross-sectional shape as the copper tube is welded to the two ends of the tube at the annular opening, thus forming a complete mechanical closed-loop circuit. This built-in baffle internally separates the annular fluid channel, forming two independent ports. The cooling water inlet a and outlet b are welded to these two ports respectively, allowing cooling water to flow in from one side, complete a full circle along the annular channel formed by the copper tube, and then flow out from the other side. This independent circulating cooling water circuit design ensures that the induced heat generated by the Faraday ring 5 during operation is promptly removed, preventing overheating and deformation or impact on the surrounding environment, thus guaranteeing the long-term reliable operation of the device.

[0031] In terms of installation structure, the upper coil 3, lower coil 4, and the middle Faraday ring 5 need to be assembled into a whole using reliable insulation and fixing components. This invention uses a column made of RF-4 (epoxy resin laminated glass cloth) as the insulation component. Equally spaced fixing holes are drilled on the surface of this column. Simultaneously, studs of equal spacing are welded to the outer diameters of the upper coil 3 and lower coil 4. By aligning and tightening the fixing holes on the column with the studs on the coils, the upper and lower coils and the middle Faraday ring 5 can be firmly fixed together. Typically, 3 to 4 such insulation fixing structures are evenly arranged along the circumference of the entire coil assembly to ensure uniform mechanical strength and reliable electrical insulation.

[0032] The working principle and steps of the large-scale suspension melting device of this invention are as follows: First, the metal raw material to be melted is filled into the water-cooled copper crucible 2, the furnace chamber 1 is closed and evacuated, and then argon gas is introduced to the required pressure. The power supply 6 is started, supplying power to the upper coil 3 and the lower coil 4 simultaneously or sequentially through its two output terminals 61 and 62. The lower coil 4 is supplied with a high-frequency current of 10-15kHz, generating a strong electromagnetic field in the lower region of the crucible, which rapidly and efficiently heats the material in this region through induction, quickly forming an initial molten pool and providing the main electromagnetic levitation force, reducing contact between the melt and the side wall and bottom of the crucible, forming a thinner solidified shell. At the same time, the upper coil 3 is supplied with a low-frequency current of 3-5kHz, which generates a magnetic field with a large penetration depth, effectively acting on the solid or semi-solid material in the upper and even central regions of the crucible, uniformly heating it to the melting temperature and continuously supplying heat to the molten pool. The Faraday ring 5 located between the two coils effectively isolates the mutual interference between magnetic fields of different frequencies, ensuring the independence and stability of their respective heating and levitation effects. Throughout the melting process, the cooling water circuit of Faraday ring 5 operates continuously to control its temperature. After melting is complete, the entire inductor assembly and crucible can be tilted together by driving the rotatable electrode spindle, allowing the pure molten metal to be poured into a predetermined mold, completing the forming process. Through the above method, this invention successfully achieves efficient, uniform, and stable suspension melting of large-sized, refractory metal materials.

[0033] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A large-scale suspension melting apparatus, comprising a vacuum furnace chamber (1) and a crucible (2) and a coil disposed within the furnace chamber (1), characterized in that: The coil includes an upper coil (3) and a lower coil (4) wound around the outside of the crucible (2). The upper coil (3) and the lower coil (4) are respectively connected to a power supply (6) located outside the furnace chamber (1). The lower coil (4) is configured to generate a frequency higher than that generated by the upper coil (3).

2. The large-scale suspension smelting apparatus according to claim 1, characterized in that: The upper coil (3) uses a frequency of 3-5 kHz, and the lower coil (4) uses a frequency of 10-15 kHz.

3. The large-scale suspension smelting apparatus according to claim 1, characterized in that: The upper coil (3) and the lower coil (4) have the same inner diameter, and both are cylindrical structures.

4. The large-scale suspension smelting apparatus according to any one of claims 1-3, characterized in that: A Faraday ring (5) is provided between the upper coil (3) and the lower coil (4). The Faraday ring (5) has the same inner diameter as the coil and is fixed to the upper and lower coils as a whole by an insulating component.

5. The large-scale suspension smelting apparatus according to claim 4, characterized in that: The Faraday ring (5) is made of copper and is equipped with a separate circulating cooling water channel.

6. The large-scale suspension smelting apparatus according to claim 5, characterized in that: The upper coil (3) and the lower coil (4) share a rotating electrode spindle for power supply. The spindle has two output terminals (61, 62) and is connected to two sets of coils respectively.

7. The large-scale suspension smelting apparatus according to claim 6, characterized in that: The upper coil (3) and the lower coil (4) have the same number of turns.

8. The large-scale suspension smelting apparatus according to claim 6, characterized in that: The upper coil (3) and the lower coil (4) have different numbers of turns.

9. The large-scale suspension smelting apparatus according to claim 7, characterized in that: The pitch of the Faraday ring (5) is equal to the pitch of the upper coil and / or the lower coil.

Images