The melting and crucible tilting and casting system is a core component of a vacuum melting furnace. The rationality of its design directly impacts the efficiency, safety, and product quality of the melting process. This system primarily consists of the following components:
- Hydraulic tilting mechanism
- Position detection device (angle meter)
- Short network system (power interface device)
- Melting crucible device
The precise design and coordinated operation of each part ensure the smooth progression of the melting process and provide safe and reliable casting operations.
Hydraulic Tilting Mechanism
The hydraulic tilting mechanism controls the tilting angle of the crucible to complete the melting and casting processes. This mechanism plays a critical role in various working conditions:
- Melting Stage: During the melting process, the hydraulic tilting mechanism controls the tilting angle of the crucible. It rocks the furnace to prevent raw materials from bridging or accumulating, ensuring uniform metal melting. This design helps to improve melting efficiency and reduce melting time.
- Casting Stage: During casting, the tilting mechanism adjusts the tilting speed of the crucible as needed, ensuring the stable flow of molten metal into the mold. The hydraulic system can precisely control the casting point, preventing chaotic metal flow.
The tilting mechanism is designed to allow the crucible’s tilting angle range to be from -10° to +100°, ensuring that it provides the appropriate tilt for different operational requirements. Particularly in the casting process with large-tonnage crucibles, to avoid excessive temperature loss, the tilting process can operate in an electrically heated mode, which compensates the temperature of the molten steel in a timely manner.
Position Detection Device (Angle Meter)
To monitor the position and tilting angle of the crucible in real time, the system is equipped with an angle meter. This device is mounted on the tilting rotation axis and changes synchronously with the tilting movement. Through integration with the control system, the angle meter can display the crucible’s tilting angle in real time, providing precise tilting data. This information is displayed on the Human-Machine Interface (HM), allowing operators to remotely monitor the crucible’s tilting position.
This function is further supported by dual confirmation through video surveillance and position display systems, ensuring the safety of the equipment. In casting operations, real-time angle monitoring and video feedback effectively prevent human errors and reduce operational risks.
Short Network System Design
The short network system is a critical electrical connection in the vacuum melting furnace, typically used to deliver power to various electrical components inside the furnace, such as induction coils. The short network design for large-tonnage crucibles is quite complex and generally needs to address the following factors:
- Double-side power line design: Large-tonnage crucibles require higher current support, so the short network is typically designed with power lines on both sides to ensure uniform current distribution and reduce resistance losses.
- Water-cooled cable configuration: The number of water-cooled cables varies depending on the stirring method. For three-phase stirring, the number of water-cooled cables is usually a multiple of 3, while for single-phase stirring, it is a multiple of 2. This design ensures that the current is adequately cooled, preventing overheating that could cause equipment failure.
- Vacuum insulation treatment: All short networks inside the furnace need to undergo vacuum insulation treatment and be subjected to glow discharge testing to ensure the safety and reliability of the electrical system. The melting voltage typically does not exceed 600V, with common voltage specifications being 575V and 460V.
Crucible Interchangeability Design
For large vacuum melting furnaces, especially large furnaces, multiple crucibles are often configured. These crucibles can be flexibly configured and exchanged based on different production requirements, making production scheduling more flexible. This design enables the functionality of “one furnace, multiple uses; one machine, multiple furnaces,” greatly improving production efficiency and resource utilization.
For example, a 6-ton vacuum furnace can be equipped with crucibles of different sizes, such as 500kg, 3 tons, etc., to accommodate various material development and production needs, reducing equipment investment costs.
In addition, large vacuum furnaces are designed for compatibility. They can not only melt high-temperature molybdenum alloys but also perform deformable melting. The design of crucible leakage detection and grounding systems is also crucial. To ensure operational safety, DC injection leakage alarms are commonly used.
Steel Leakage Detection and Grounding System
The steel leakage detection system measures the resistance between the furnace lining and the induction coil. After setting a safe resistance value, the computer continuously monitors and issues an alarm if abnormal resistance is detected. The system can promptly cut off the power supply to prevent steel leakage caused by a thin furnace lining, cracks, or other faults.
Grounding/leakage detectors are also vital. These devices continuously monitor the grounding status of the crucible to ensure that molten steel does not pose a safety threat to operators or equipment. The system is typically equipped with indicator lights, milliamp meters, adjustable sensitivity controllers, and testing circuit buttons.
When the system detects the following four conditions, the device will automatically display an alarm and cut off the main power supply:
- Furnace lining is too thin or cracked: The DC injection protection mechanism is activated to prevent electrical leakage.
- Molten metal leaks from the furnace lining into the coil: Protection is immediately activated when metal leakage occurs.
- Furnace lining is wet: Excessive humidity may cause short circuits or electrical failures.
- Poor grounding of the furnace or power system: Improper grounding may lead to instability in the electrical system, and the system will automatically protect itself.
Conclusion
The design of the melting and crucible tilting and casting system is crucial for ensuring the efficient and safe operation of a vacuum melting furnace. The hydraulic tilting mechanism provides precise control of the tilting angle, while the angle meter and video system ensure real-time monitoring and safety. The short network system and crucible interchangeability design enhance production flexibility and equipment utilization. Additionally, the steel leakage detection and grounding system, with its high-precision safety measures, prevents equipment failure and operational risks. Overall, the accurate design and intelligent safety monitoring systems provide strong guarantees for the reliability and efficiency of the vacuum melting furnace.
