Vacuum induction melting is a special smelting technology that uses a medium-frequency power supply to energize a copper coil, generating a strong magnetic field that forms eddy currents. These currents induce heating in solid metals, melting them in a high-vacuum environment. Due to the good vacuum atmosphere, this technique can effectively remove oxygen, nitrogen, and other elements from nickel-based high-temperature alloys during the melting process. As a result, vacuum induction melting has become the main method for producing high-performance high-temperature alloys and is widely used worldwide. In recent years, driven by the growing demand for advanced materials in downstream industries, domestic vacuum induction melting technology has rapidly developed.
With the industrial upgrade of the traditional metallurgy sector and the strong demand for special metallurgy high-end materials, vacuum induction melting equipment has gradually evolved toward larger, multifunctional, high-performance, and intelligent designs. A large-scale, high-end vacuum induction melting furnace must integrate research and development, production, digital intelligence, and safety assurance into a complete system. Multifunctionality, high performance, and intelligence are the fundamental points of departure for designing large vacuum melting equipment.
The following provides an overview of the design of vacuum induction melting furnace. For detailed designs of various components, click on the respective titles for more information.
Overview of Vacuum Induction Melting Furnace
A Vacuum Induction Melting Furnace (VIM) is mainly used to melt precision alloys, electromagnetic materials, alloy steels, and high-temperature alloys. Melting in a vacuum environment makes it easier to remove or reduce detrimental elements like nitrogen, hydrogen, oxygen, and carbon from metals. It also allows for adjustment of the chemical composition of the alloying elements, thereby improving the material’s toughness, fatigue strength, corrosion resistance, high-temperature creep resistance, and the magnetic permeability of magnetic alloys.
Based on the furnace structure, vacuum induction furnaces are classified into periodic and semi-continuous types. Depending on the product being produced, they can also be classified into deformation alloy melting furnaces and high-temperature master alloy melting furnaces.
Large vacuum induction melting furnaces are typically custom-designed, tailored to specific melting processes, with diverse forms and structures. They generally consist of a vacuum generation system, power and melting systems, cooling water system, hydraulic system, pneumatic system, electrical control system, feeding system (top feeding + side feeding), temperature measurement and sampling systems, windows and camera systems, furnace tilting and casting devices, flow casting systems, short-net devices, and other components.
1. Design of the Vacuum Generation System
The vacuum system is a critical component of the vacuum melting equipment. For large multifunctional vacuum induction melting furnaces, the vacuum system is both large and complex, requiring a customized design based on the process route. This system mainly includes vacuum pumps, vacuum pipelines, vacuum valves, flow transmitters, vacuum filtration systems, vacuum pressure sensors, temperature sensors, safety devices, dust removal systems, and soft connections.
2. Design of the Cooling Water System (Equipment and Power Water Systems)
The entire melting and casting process in a VIM furnace occurs continuously in a high-vacuum, high-temperature environment. On one hand, the furnace environment is very hot during melting, with a large crucible diameter and significant heat radiation, which necessitates timely water cooling for the vacuum chamber and certain components to ensure safe operation. On the other hand, during the casting process, a large amount of heat is released when the metal transitions from liquid to solid, requiring cooling of the chamber and molds. The melting power supply and induction coil systems also require deionized water for cooling electrical components. There are two types of water system designs: one is an open-loop water circulation system, where water is supplied directly from an outdoor cooling tower; the other is a closed-loop water circulation system, where water is supplied from an indoor collection tank, forming a closed-loop water cycle.
3. Design of the Hydraulic System
The hydraulic system of a VIM furnace is designed with complexity and precision. Different hydraulic units are responsible for the hydraulic needs of melting, casting, and external furnace operations. Through reasonable design and configuration, each segment operates efficiently and ensures equipment safety. The first hydraulic unit undertakes the main execution tasks, the second unit ensures safety during tilting and casting, and the third unit is responsible for auxiliary functions such as furnace lining ejection and baking. The system uses a dual-pump and dual-motor configuration and is equipped with safety valves, ensuring the reliability of the equipment and ease of long-term maintenance. This multi-unit, independent control design allows the hydraulic system to better handle various operating conditions, improving safety, reliability, and flexibility.
4. Design of the Melting and Crucible Tilting/Pouring Device
The design of the melting and crucible tilting/Pouring device is crucial to ensuring the efficient and safe operation of the vacuum melting furnace. The hydraulic tilting mechanism provides precise control over tilting, while the angle meter and video camera system ensure real-time monitoring and safety of the operation. The short-net system and interchangeable crucible design increase production flexibility and equipment utilization. Additionally, steel leakage detection and grounding systems use high-precision safety measures to avoid equipment failure and operational risks. Overall, the precise design and intelligent safety monitoring system provide strong support for the reliability and efficiency of the vacuum melting furnace.
5. Design of the Power Supply System
The power supply system is designed to ensure efficient and safe operation of the equipment under various operating conditions by properly selecting power control, stirring modes, and protection mechanisms. Whether under light or heavy load, or in different furnace applications, the power supply system can provide stable electrical support, pushing the vacuum induction melting furnace towards greater efficiency and reliability.
6. Design of the Feeding Device
The feeding system of large vacuum melting furnaces, particularly the vibration side feeding system, significantly improves production efficiency and operational flexibility. By combining top and side vibration feeding systems, the feeding method can be adjusted as needed during production, ensuring efficient and uniform material feeding into the furnace. The vibration side feeding system not only speeds up the feeding process and controls the accuracy of material input but also reduces safety risks like bridging, enhancing the reliability and safety of the feeding process. Overall, the modern feeding system greatly improves the production efficiency of the vacuum melting furnace, optimizes equipment operation, reduces manual intervention, and further promotes a high-efficiency, flexible production mode.
7. Design of the Temperature Measurement and Sampling Devices
The design of the temperature measurement and sampling devices integrates immersion thermocouples, optical pyrometers, sampling devices, and the top feeding function, reducing operational steps and improving automation. This multifunctional integrated design reduces the workload of operators and simplifies equipment maintenance. By integrating these functions, operations like feeding, temperature control, and sampling during production become simpler and more efficient, ensuring stable melting processes and accurate temperature control of high-temperature alloys.
In conclusion, the design of vacuum induction melting furnace integrates multiple systems that work in harmony to ensure efficient, safe, and reliable operation. Key components such as the vacuum generation system, cooling water system, hydraulic system, power supply system, feeding device, and temperature measurement system are all designed with precision to meet the complex demands of high-performance alloy melting. The continuous evolution toward larger, multifunctional, high-performance, and intelligent designs is a natural progression, driven by the growing demand for advanced materials. By focusing on safety, efficiency, and flexibility, modern vacuum induction melting furnaces are well-equipped to support the production of high-end alloys in various industrial applications.
