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FUJI ELECTRIC JOURNAL 1998 Vol.71-No.5
Present Status and Prospects for Induction Heating
Kinzou Okazaki, Michio Kawasaki
Induction heating has been developed as a key technology supporting present-day living because of its superior characteristics. It reduces energy consumption, contributes to the protection of environment, and improves productivity. This paper describes its technical trends classified by application fields from the viewpoint of its position in electric heating and the trend of demand. Also it refers to Fuji Electric's achievements in induction heating technologies, particularly developments in numerical analysis, high-frequency power supply, and systems.
Application of Numerical Analysis to Industrial Electrical Heating Products
Kengo Kainuma, Masaki Sakuma
Computer-based numerical analysis has recently come into frequent use for the development and design of electrical products. Fuji Electric utilizes simulation with computer for the electromagnetic field, heat flow, structure, and fluid flow of industrial induction heating products to optimize specifications and structures and reduce lead time. This paper introduces some typical examples of analytical techniques and calculation results in simulations applied to induction heating and electromagnetic-force-applied equipment.
Recent Development of Levitation Melting Equipment
Hideaki Tadano, Kengo Kainuma
This paper describes the recent development of levitation melting equipment to melt metals floating in the air in a crucible. Aiming at stable levitation melting in the several kg class, (1) a duplex inverter configuration has been used and (2) the bottom shape of crucibles has been optimized. Aiming at industrialization, (1) noncontacting extraction of melt from the crucible bottom and (2) a large melt capacity in the 50 kg class have been attained. Fuji Electric completed a series of the cold crucible levitation melting "CCLM" and also has marketed new products for various fields such as large capacity CCLM, continuous casting equipment, and high vacuum CCLM.
Metallurgical Advances in Cold Crucible Levitation Melting Equipment
Tsuneki Shinokura, Tatsuo Take
The features of the cold crucible levitation melting (CCLM) have been verified by melting various kinds of metals and alloys. The principle of levitation melting and tapping, the basic structure and features of CCLM, and comparison with other melting methods are described. The specifications and external views of the experimental instruments (for 2 kg high vacuum CCLM, 50 kg CCLM, and continuous casting CCLM) are shown. The metallurgical examples are the melting of Co, TiAl, Fe-Al2 O3, and Cu-Cr alloys, the melting and tapping of cast iron and stainless steel, and the continuous casting of lead and gray iron. In addition, CCLM applications are referred to.
High-Frequency Power Sources for Induction Heating
Masaaki Hisamoto, Yutaka Itoh, Toshihiro Nomura
High-frequency induction heaters using power semiconductor devices are widely spreading due to the clean, highly efficient, and easily controllable heating. Fuji Electric produces the following three types of inverters for induction heating : (1) thyristor inverters (current source type) up to 10 kHz, up to 12 MW, water-cooled, (2) general-purpose IH inverters (IGBT voltage source type) up to 50 kHz, up to 20 kW, air-cooled, (3) MOSFET inverters (voltage source type) up to 500 kHz, up to 1 MW, water-cooled. This paper describes the features, specifications, and schematic circuits of these inverters and the brief comparison of the current and voltage source types for high-frequency induction heaters.
New Induction Furnace for Galvanized Steel Scrap Melting
Masahiro Nakatani, Hiroshi Uemura
The mixing of galvanized steel scrap in steel scrap for main melt material in pig iron foundries has become unavoidable. The melting of galvanized steel scrap in a conventional furnace has caused many troubles due to zinc such as shorter refractory life, lower cast quality, and pollution in the working environment. The new induction furnace developed to solve these problems has many advantages of recycling galvanized steel scrap, energy-saving melting, and improved melt properties. This paper describes the background of the development, system configuration, evaluation tests, and features of the furnace.
Energy-Saving Induction Furnaces
Toshiyuki Kano, Yasuhiko Kojo
The global preservation of the environment is cried for, and also industrial furnaces are required to be improved in view of the environment and energy saving. This paper describes the advantages of induction furnaces from the viewpoint of the environment and energy. Then it refers to the high efficiency and low energy consumption, the greatest advantages of Fuji Electric's high-frequency induction furnace, and its original furnace technology.
Recent Seam-Welding Equipment
Iwao Kurata, Kiyokazu Nakamura
Seam weld tubes are produced by tubing beltlike metal strips and seam-welding them. Formerly, seam welding power sources used a high-frequency vacuum-tube oscillator. The oscillator efficiency was low and a more efficient power source was desired from the viewpoint of energy saving and rationalization. Fuji Electric has developed a high-efficiency seam welding equipment using a high-frequency MOS FET inverter, which is in operation in an actual line. This paper describes the principle of seam welding, welder configuration, and the comparison of welding capacity with the vacuum oscillator.
Application of Induction Heating in Steel Works
Yasuyuki Ikeda, Sakae Okayama, Koichi Ando
There are many applications of induction heating in steel works for the purpose of heating, increasing temperature, heat treatment and /or melting, which has the advantages such as energy saving, rapid heating, good controllability and responsiveness to temperature. As application examples of induction heating to steelworks processes, this paper cites a new strip induction heater which can also heat a very thin steel sheet (thickness : 0.1 mm) with a high-frequency MOSFET inverter, a sheet bar heater used in the hot rolling process, and a galvalume pot (an induction furnace for galvalume plated steel sheets increasing in demand among surface-treated steel sheets).
Application of Induction Heating to Waste Treatment
Kiyonori Kida, Kiyomi Wada, Mitsuo Harada
Under the global environment at issue, the way of waste treatment is strictly inquired. Recently, harmful dioxin has become a problem, and the compressed waste hot-binder developed by Fuji Electric attracts attention as a treatment system for unburned high polymer waste. Fuji Electric is also developing a system in which flammables mainly composed of high polymer waste along with recyclable materials exhausted from large refuse treatment or recycling facilities are treated by dry distillation and made harmless for exhausting. The result of experimental dry distillation and future prospects for this system are also described.
Hybrid Melting System for Recycling Aluminum Beverage Cans
Hidemi Hattori
Aluminum wastes such as chips with small heat capacities and large surface areas had many problems such as the poor yield of melt, difficult safe operation, and pollution to the working environment. Recently, jointly with a foundry, Fuji Electric has developed a new melting system "electromagnetic vortex stirrer" (gas-electric hybrid melting system) utilizing electromagnetic force which can efficiently melt aluminum wastes such as chips and beverage cans that were difficult to melt with a conventional reverberatory furnace and also can improve the yield of melt and the working environment.
Inductively Coupled Plasma Torch Using a High-Frequency Inverter
Yasushi Sakakibara, Genichi Katagiri
An inductively coupled plasma (ICP) torch is a thermal plasma generator used for treating wastes and hazardous substances. When it is compared with a DC plasma torch, the most advantage is plasma generation without electrode. However, the ICP is driven by a vacuum-tube power source of several MHz, and so energy loss in the power source is large and the plasma size is approximately 3 cm in radius. Fuji Electric is developing an ICP torch with a large bore using a low-loss MOSFET inverter for the power source. This paper describes numerical analysis for the ICP and the result of plasma generation with a torch made on an experimental basis.
