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In modern industrial and technological fields, precious metals have extremely high value and wide applications due to their unique physical and chemical properties. In order to meet the high-quality requirements for precious metal materials, high vacuum continuous casting equipment for precious metals has emerged. This advanced equipment uses high vacuum technology to cast precious metals in a strictly controlled environment, ensuring the purity, uniformity, and performance of the product. This article will provide a detailed introduction to the high vacuum continuous casting equipment for precious metals and its applications.

vacuum continuous casting equipment

1、Overview of High Vacuum Continuous Casting Equipment for Precious Metals

Equipment composition

1. Vacuum system

High vacuum pump: Usually a combination of mechanical pump, diffusion pump, or molecular pump is used to achieve a high vacuum environment. These pumps can quickly reduce the pressure inside the equipment to extremely low levels, eliminating interference from air and other impurities.

Vacuum valves and pipelines: used to control the vacuum degree and gas flow, ensuring the stable operation of the vacuum system.

Vacuum gauge: monitors the vacuum level inside the equipment and provides accurate vacuum status information for operators.

2. Smelting system

Heating device: It can be induction heating, resistance heating, or arc heating, and can heat precious metals to a molten state. Different heating methods have their own characteristics and applicability, and can be selected according to the type of precious metal and process requirements.

Crucible: Used to hold precious metal melts, usually made of materials that are resistant to high temperatures and corrosion, such as graphite, ceramics, or special alloys.

Stirring device: Stirring the melt during the melting process to ensure uniformity of composition and temperature consistency.

3. Continuous casting system

Crystallizer: It is a key component in the continuous casting process, which determines the shape and size of the ingot. Crystallizers are usually made of copper or other materials with good thermal conductivity, and are internally cooled by water to accelerate the solidification of precious metal melts.

Ingot introduction device: Extract the solidified ingot from the crystallizer to ensure the continuous operation of the continuous casting process.

Pulling device: controls the pulling speed of the ingot, affecting the quality and production efficiency of the ingot.

4. Control system

Electrical control system: Electrical control of various parts of the equipment, including adjustment of parameters such as heating power, vacuum pump operation, and billet pulling speed.

Automated control system: It can achieve automated operation of equipment, improve production efficiency and stability of product quality. Through preset programs, the control system can automatically complete processes such as melting and continuous casting, and monitor and adjust various parameters in real-time.

2、Main structural description

1. Furnace body: The furnace body adopts a vertical double-layer water-cooled structure. The furnace cover can be opened for easy insertion of crucibles, crystallizers, and raw materials. The upper part of the furnace cover is equipped with an observation window, which can observe the condition of the molten material during the melting process. The induction electrode flange and vacuum pipeline flange are symmetrically arranged at different height positions in the middle of the furnace body to introduce the induction electrode joint and connect it with the vacuum device. The furnace bottom plate is equipped with a crucible support frame, which also serves as a fixed pile to accurately fix the position of the crystallizer, ensuring that the center hole of the crystallizer is concentric with the sealed channel on the furnace bottom plate. Otherwise, the crystallization guide rod will not be able to enter the interior of the crystallizer through the sealed channel. There are three water-cooled rings on the support frame, corresponding to the upper, middle, and lower parts of the crystallizer. By controlling the flow rate of cooling water, the temperature of each part of the crystallizer can be precisely controlled. There are four thermocouples on the support frame, which are used to measure the temperature of the upper, middle, and lower parts of the crucible and crystallizer, respectively. The interface between the thermocouple and the outside of the furnace is located on the furnace floor. A discharge container can be placed at the bottom of the support frame to prevent the melt temperature from directly flowing down from the cleaner and causing damage to the furnace body. There is also a detachable small rough vacuum chamber in the center of the furnace floor. Below the coarse vacuum chamber is an organic glass chamber, where antioxidants can be added to improve the vacuum sealing of the filaments. This material can achieve antioxidant effect on the surface of copper rods by adding antioxidants to the organic glass cavity.

2. Crucible and Crystallizer: The crucible and crystallizer are made of high-purity graphite. The bottom of the crucible is conical and connected to the crystallizer through threads.

3. Vacuum system

4. Drawing and winding mechanism: The continuous casting of copper bars consists of guide wheels, precision wire rods, linear guides, and winding mechanisms. The guide wheel plays a guiding and positioning role, and when the copper rod is taken out of the furnace, it first passes through the guide wheel. The crystal guide rod is fixed on the precision screw and linear guide device. Firstly, the copper rod is pulled out (pre pulled) from the furnace body through the linear motion of the crystallization guide rod. When the copper rod passes through the guide wheel and has a certain length, it can cut off the connection with the crystal guide rod. Then fix it on the winding machine and continue to pull the copper rod through the rotation of the winding machine. The servo motor controls the linear motion and rotation of the winding machine, which can accurately control the continuous casting speed of the copper rod.

5. The ultrasonic power supply of the power system adopts German IGBT, which has low noise and energy saving. The well uses temperature control instruments for programmed heating. Electrical system design

There are overcurrent, overvoltage feedback, and protection circuits.

6. Control system: This equipment adopts a touch screen fully automatic control system, with multiple monitoring devices, to accurately control the temperature of the furnace and crystallizer, achieving the long-term stable conditions required for copper rod continuous casting; Multiple protection measures can be taken through monitoring equipment, such as material leakage caused by high furnace temperature, insufficient vacuum, pressure or water shortage. The device is easy to operate and the main parameters are set properly.

There are furnace temperature, upper, middle, and lower temperatures of the crystallizer, pre pulling speed, and crystal growth pulling speed.

And various alarm values. After setting various parameters, in the production process of copper rod continuous casting, as long as safety is ensured.

Place the crystallization guide rod, place the raw materials, close the furnace door, cut off the connection between the copper rod and the crystallization guide rod, and connect it to the winding machine.

3、 The use of high vacuum continuous casting equipment for precious metals

（1） Produce high-quality precious metal ingots

1.High purity

Smelting and continuous casting in a high vacuum environment can effectively avoid contamination from air and other impurities, thereby producing high-purity precious metal ingots. This is crucial for industries such as electronics, aerospace, and healthcare that require extremely high purity of precious metal materials.

For example, in the electronics industry, high-purity precious metals such as gold and silver are used to manufacture integrated circuits, electronic components, etc. The presence of impurities can seriously affect their performance and reliability.

2.Uniformity

The stirring device and continuous casting system in the equipment can ensure the uniformity of the composition of the precious metal melt during the solidification process, avoiding defects such as segregation. This is of great significance for applications that require high uniformity of material properties, such as precision instrument manufacturing and jewelry processing.

For example, in jewelry processing, uniform precious metal materials can ensure consistent color and texture of jewelry, improving product quality and value.

3.Good surface quality

The surface of ingots produced by high vacuum continuous casting equipment is smooth, without pores or inclusions, and has good surface quality. This can not only reduce the workload of subsequent processing, but also improve the appearance quality and market competitiveness of the product.

For example, in high-end manufacturing, precious metal materials with good surface quality can be used to manufacture precision parts, decorations, etc., meeting customers’ high requirements for product appearance and performance.

（2） Developing new precious metal materials

1.Accurately control the composition and structure

High vacuum continuous casting equipment for precious metals can accurately control the composition and temperature of the precious metal melt, thereby achieving precise control over the composition and structure of the ingot. This provides a powerful means for the development of new precious metal materials.

For example, by adding specific alloying elements to precious metals, their physical and chemical properties can be altered, leading to the development of new materials with special properties such as high strength, high corrosion resistance, and high conductivity.

2.Simulate the casting process in special environments

The equipment can simulate special environments such as different pressures, temperatures, and atmospheres to study the casting behavior and performance changes of precious metals in these environments. This is of great significance for developing precious metal materials that can adapt to special working conditions.

For example, in the aerospace industry, precious metal materials need to work in harsh environments such as high temperature, high pressure, and high radiation. By simulating these environments for casting experiments, new materials with excellent performance can be developed to meet the needs of the aerospace industry.

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