At present, induction furnace, holding furnace, heat treatment furnace and other metal smelting production equipment are favored by metallurgical casting and roll manufacturers because of their advantages such as easy to change melting varieties, easy to control melting quality, flexible and simple operation, high power density, fast melting speed, high thermal efficiency and easy melting. Many foundries and roller factories have purchased and installed induction furnaces to replace the traditional cupola and power frequency furnaces. For example, Jiangsu Yixing gongchang roller Co., Ltd., which is famous for strengthening science and technology and prospering great cause, achieved gratifying production and operation performance and remarkable technical and economic benefits in June 2001 due to the newly built modern all medium frequency electric furnace workshop. In order to further promote the popularization of medium frequency induction furnace, since 1966, BBC, a Swiss company, successfully developed the first thyristor medium frequency power supply device for induction melting, a series of products have been launched in various industrialized countries, which soon replaced the traditional rotary frequency conversion power supply of medium frequency generator and various old smelting and heating equipment. Due to its high efficiency, short manufacturing cycle, simple installation and easy to realize automatic control, thyristor medium frequency power supply is widely used in various industrial fields, such as induction melting, heat preservation, diathermy, quenching, sintering and brazing. Recently, it has been applied in environmental protection, grain storage, seed treatment, funeral and other fields, showing strong vitality. With the rapid development of microelectronic technology, great changes have taken place in the medium frequency power supply. The application of microelectronic technology has greatly expanded and enhanced the control function of the medium frequency power supply, improved the reliability and stability. The power supply is becoming larger and larger, the volume is becoming smaller and smaller, and the cost is becoming less and less, which has been unanimously recognized and welcomed by people in the industry. At present, the capacity of induction melting furnace in the world has exceeded 20 tons, the capacity of holding furnace has exceeded 50 tons, and the automatic heating of various metals is widely used.

1、 Characteristics and advantages of induction furnace The complete set of equipment of medium frequency induction furnace is to convert three-phase alternating current into direct current after rectification, and then convert direct current into adjustable medium frequency current to supply medium frequency alternating current flowing through capacitor and induction coil. High density magnetic lines of force are generated in induction coil, and the metal materials in induction coil are cut to produce large eddy current in metal materials. This kind of eddy current also has some properties of intermediate frequency current, that is, the free electrons of metal flow in the metal body with resistance to generate heat. For example, if a metal cylinder is placed in an induction coil with alternating medium frequency current, the metal cylinder does not directly contact with the induction coil, and the temperature of the coil itself is very low, but the surface of the cylinder is heated to reddening or even melting, and the reddening and melting speed can be achieved by adjusting the frequency and the current strength. If the cylinder is placed in the center of the coil, the temperature around the cylinder is the same, and the heating and melting of the cylinder do not produce harmful gas and strong light pollution. Because of the above advantages, medium frequency induction furnace has been widely used in various industries. For example, in the roller industry: three years ago, most roller factories used cupola coke furnace to smelt hot metal, the composition of hot metal produced by Cupola can not be adjusted, the temperature is difficult to control, the quality of cast roller is poor, the yield is low, and the benefit is poor. Moreover, the hot metal temperature of this cupola can't rise to 1600 ℃, so it can't produce high-grade steel roller, which makes our country's high-grade roller depend on import. In the past two years, the main roll manufacturers in China have successively adopted the medium frequency induction furnace to smelt hot metal and alloy steel to produce rolls, which has raised the production level of rolls in China to a great level and achieved obvious benefits. In the foundry industry, due to the high price of foreign medium frequency electric furnace, many domestic users are deterred, so they can only buy power frequency electric furnace to smelt molten iron and steel. Because the power frequency of 50 cycles is too low, it is difficult to compensate the power after the first furnace is started. It can only be compensated slowly. It will take several hours for the full power output, which wastes time and reduces the efficiency. After the molten iron is smelted, it is not allowed to pour all the molten iron, and a part of the molten iron needs to be left in the furnace, otherwise the smelting cannot be started for the second time. Because of low frequency, molten iron tumbles too much in the furnace, slag and inclusions are stirred in the liquid, which affects the quality of molten steel. More and more units have recently transformed the frequency furnace into the medium frequency furnace. After a foundry changed a set of 3-ton power frequency furnace into intermediate frequency furnace, it was easy to use and the benefit was obviously improved. Therefore, the power frequency furnace was gradually eliminated by the smelting industry and replaced by intermediate frequency induction furnace. In the early days of smelting industry, electric arc furnace is also used a lot. This kind of equipment is that the electrodes are short circuited to each other through carbon rods to produce short-circuit high current, and then generate high temperature to melt molten iron or steel. The disadvantage of this kind of equipment is that when it produces high temperature, it will produce dazzling arc light, stab the operator's eyes, and produce harmful powder gas, polluting the environment. When it produces high temperature above 1000 ℃, it will also burn the precious elements in the molten steel, reduce the effective yield of molten steel and elements, increase the cost, and burn the furnace wall. In particular, the lining life of small tonnage electric furnace is very low, and the relevant departments of the State Economic and Trade Commission have clearly stipulated that the electric arc furnace of less than 10 tons cannot be used. Therefore, these users have replaced the electric arc furnace with medium frequency electric furnace in order to improve the efficiency of enterprises.

2、 Development of medium frequency induction furnace in China In China, the research and manufacture of medium frequency induction furnace is relatively early. In 1969, the former First Machinery Department started the organized research and development. However, for various reasons, until 1996, the medium frequency induction furnace in China was still in a low-level production state. The power of medium frequency power supply was around 1000kW, and the electric furnace was about 2T. The key trigger system of medium frequency generally adopted discrete components, and the control AC adopted open-loop Control, use stability is generally poor. In the previous period, some domestic medium frequency induction furnace manufacturers had a bad reputation, while the high-power and large tonnage medium frequency induction furnace mainly depended on imports from Europe and the United States. Due to the high price (5-10 times of China's products) and few users, the development of high-quality products in China's Metallurgical industry was directly affected. With the rapid pace of China's integration with the world economy, in the smelting, casting and hot processing industries, the demand for reliable and stable high-power medium frequency power supply, large tonnage smelting furnace and induction heating furnace is rising rapidly. In this situation, the localization of high-power, large tonnage induction furnace is imminent. Therefore, domestic electric furnace manufacturers are making every effort to develop this product and connect with the world Track.

3、 The prospect of medium frequency induction furnace in the new century after China's entry into WTO, the metallurgical and foundry industry will develop vigorously in China, and the developed countries in the world will take the opportunity to push the castings to the Chinese market. Obviously, the domestic demand for medium frequency induction furnace is also rising rapidly, the product market is larger, and the competition is more and more fierce. Although the world's first-class manufacturers have high prices and can use high technology to occupy the market, their market in China is shrinking due to high production costs (especially high wages for engineering and technical personnel). China's first-class induction furnace manufacturers are approaching the world's advanced level with each passing day. Although there is still a gap, they are rapidly expanding the market due to reasonable price and good service, and are pushing to the world market.

Yiphee Electric Furnace Co.,Ltd specializes in producing induction smelting furnace.Tel(WhatsApp):+86-13450756789, yiphee@yiphee.cn