Advantages and prospects of the hottest electromag

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Advantages and prospects of electromagnetic stirrer in continuous casting

at present, electromagnetic technology has been widely used in iron and steel production processes, especially in the field of continuous cast steel, which is highlighted by the promotion and application of mature technology and the development and industrialization of new technology. Electromagnetic Technologies in the field of continuous casting mainly include electromagnetic stirring, electromagnetic braking, electromagnetic casting and soft contact

electromagnetic stirring technology

in 1952, an experimental electromagnetic stirring device was first installed under the crystallizer of the continuous casting machine. Since the 1970s, with the continuous development of continuous casting technology and the continuous expansion of continuous casting steel grades, electromagnetic stirring technology has attracted more and more attention

the main function of electromagnetic stirring in continuous casting process is to improve the quality of continuous casting slab, such as removing inclusions, eliminating subcutaneous bubbles, reducing central segregation, and improving the equiaxed grain rate of continuous casting slab. Therefore, electromagnetic stirring technology has become the first choice when casting billets with large cross-section, such as bloom, slab and steel grades with high casting quality requirements or prone to quality problems. According to different stirring positions, continuous casting electromagnetic stirring can be divided into mold electromagnetic stirring (M-EMS), secondary cooling zone electromagnetic stirring (S-EMS) and solidification end electromagnetic stirring (F-EMS). At present, electromagnetic stirring in crystallizer is widely used in billet continuous casting. Sometimes, in order to further improve the quality, electromagnetic stirring at the end of solidification is added, that is, combined stirring at the end of solidification and crystallizer. Electromagnetic stirring in secondary cooling zone is widely used in slab continuous casting. In recent years, the application of electromagnetic stirring technology in slab crystallizer has gradually attracted the attention of iron and steel enterprises in various countries, especially in Japan

the research of electromagnetic stirring technology for continuous casting in China began in the 1970s, when the main development was to dump the mortar from the mixing bag. Since the mid-1980s, while introducing special steel casters and slab casters, China has successively introduced electromagnetic stirring devices of different positions and types. After more than 20 years of research, development, digestion and absorption, China has made great progress in the field of electromagnetic stirring technology. At present, it has been fully able to undertake the design, manufacture and industrial application of agitators, but the waterproof insulating film wrapped on the outer layer of coil wires still needs to be imported from abroad. Domestic manufacturers of electromagnetic agitators are also in a state of fierce competition, and compete with foreign manufacturers for the domestic agitator market

in general, electromagnetic stirring is the most mature and widely used in the field of electromagnetic continuous casting technology. At present, the main problem is how to further improve the service life of the electromagnetic stirrer coil. When the agitator is running, the coil is heated and needs circulating water for cooling. Due to the long-term immersion and scouring of circulating water, the waterproof film and insulating film on the surface of the coil will gradually age and become invalid, causing the insulation performance of the coil to decline and generate electric leakage. When the leakage current reaches a certain value, the coil needs to be repaired. For the built-in mold electromagnetic stirrer using mold cooling water that exceeds this current, the average service life of the current coil is about one year. Therefore, using new technology to improve the service life of the coil is the development trend of electromagnetic stirring technology

electromagnetic braking technology

in the 1980s, abb in Sweden and Kawasaki iron in Japan developed the electromagnetic braking technology of slab continuous casting mold. The original electromagnetic brake has two braking areas, which cover one end of the water outlet respectively. By the early 1990s, the electromagnetic brake had been further improved, with a single magnetic field covering the entire slab width, and later developed into two magnetic fields covering the entire slab width. At present, there are no technical problems in the design, manufacture and industrial application of electromagnetic brakes in China

the main function of electromagnetic braking is to reduce the flow of molten steel at the outlet of the nozzle, but it can be accelerated if graphene film is used, which reduces the impact depth of molten steel on the liquid cavity of continuous casting slab and is conducive to the floating of non-metallic inclusions. In addition, after adopting electromagnetic braking technology, the fluctuation amplitude of the meniscus of the mold is reduced, and the overturning of the liquid level and the involvement of the protective slag are prevented. Therefore, the metallurgical effect of electromagnetic braking is the most obvious when the pulling speed is high. The casting speed of thin slab caster is 2 to 4 times that of conventional thick slab caster, so the application of electromagnetic braking in thin slab caster is the most suitable. Most of the newly-built thin slab continuous casting machines are equipped with electromagnetic braking devices or reserved positions

The latest application of electromagnetic braking technology is to produce composite continuous casting billets. The so-called composite continuous casting slab means that the outer layer of the continuous casting slab is stainless steel or other kinds of high-quality steel, while the inner core is plain carbon steel. This is a new process for the production of composite steel plates that has just developed abroad. The process principle is: two kinds of molten steel with different chemical compositions are simultaneously injected into the same crystallizer through long and short submerged nozzles, and electromagnetic braking is applied at the interface between the two kinds of molten steel in the middle of the two nozzles to inhibit the mixing of the two kinds of molten steel. Due to the effect of electromagnetic braking force, the molten pool in the mold is divided into upper and lower parts. The cooling effect of the mold solidifies the upper liquid steel into the outer layer of the composite continuous casting slab. The lower liquid steel solidifies inside the shell to form the inner core of the composite continuous casting slab. Japan has made rapid progress in this field, and has cast composite continuous casting billets with stainless steel outer layer and plain carbon steel inner core in the laboratory, which is expected to realize industrialization in the next few years

electromagnetic casting and soft contact

electromagnetic casting is a process in which the traditional crystallizer is replaced by electromagnetic coil, and the liquid metal is suspended and constrained into a certain shape by electromagnetic force for continuous casting. Because the metal is in the state of magnetic levitation during solidification, the surface defects of traditional continuous casting billet, such as vibration marks, surface slag inclusion, peeling, etc., are avoided, and its internal quality is significantly improved due to the effect of electromagnetic field. At present, the dieless electromagnetic casting technology of aluminum has been industrialized. Although developed countries have begun to explore the dieless electromagnetic casting technology of steel since the 1970s, it is difficult to realize the dieless electromagnetic casting of steel because of its low conductivity, high density, high melting point and poor thermal conductivity, which requires a strong magnetic field to overcome the static pressure of molten steel. In this case, the soft contact continuous casting technology of steel appears

soft contact refers to that the traditional mold is still used during continuous casting, but a high-frequency electromagnetic field is applied to the meniscus area outside the mold, the side of the molten steel near the meniscus shrinks to the center under the action of electromagnetic force, and the gap with the inner wall of the mold increases, while the primary shell will produce displacement away from the mold wall. In soft contact continuous casting, the consumption of mold flux increases, the vibration marks on the surface of the slab are greatly reduced or basically disappeared, and the surface quality is greatly improved, resulting in a similar effect to that of Dieless electromagnetic casting

the difficult problem in soft contact technology is how to make the high-frequency magnetic field act on the metal through the copper tube of the mold with good conductivity as much as possible. At present, the commonly used method is to open a gap near the meniscus of the copper pipe and fill the gap with insulating material. Japan is a world leader in the development and research of soft contact continuous casting technology for steel. Sumitomo Metal researchers conducted soft contact continuous casting experiments on round billets with a diameter of 180mm and a carbon content of 0.11%; Nippon Steel Corporation conducted a 190mm diameter stainless steel round billet soft contact test; Kobe Steel Company conducted a soft contact test of 150mm carbon steel billets. Several universities and research institutes in China have used low melting point tin, tin lead alloy and gallium tin alloy for soft contact test research, and there is no report on soft contact test of steel

Komeda electromagnetic stirring technology

I) technical measures and characteristics of Komeda electromagnetic stirrer

1. Strong technical force and advanced technology. The main technicians and technicians of our company are senior technical talents who have been engaged in the research and manufacturing of electromagnetic stirrer since the early 1980s. Have rich experience in self-development and research. The electromagnetic stirrer developed and produced by our company is carefully designed and manufactured on the basis of digesting and absorbing the electromagnetic stirrer technology of foreign companies such as abb, rotelec and JME, combined with the research results of electromagnetic stirrer in China for more than 20 years. It has the characteristics of high central magnetic density, large electromagnetic volume force, good mixing effect, low energy consumption, reasonable structure and long service life. Various types of electromagnetic agitators and electromagnetic braking devices can be provided according to users' needs. The rotating magnetic field type, traveling wave magnetic field type and spiral magnetic field type electromagnetic agitators are introduced

2. Our company and the American GL electromagnetic field software company have jointly developed the SAIJIN electromagnetic field calculation method. The so-called SAIJIN electromagnetic field calculation method is to adopt a new band magnetic field calculus equation in the boundary zone and a Galerkin magnetic field differential equation in the region to form an effective SAIJIN electromagnetic mixing calculation method. This software is used to optimize the electromagnetic parameters of the electromagnetic mixer, so the magnetic density of the center of the electromagnetic mixer is high, The electromagnetic volume force is large, and the mixing effect is good. The virtual model of the calculation results of SAIJIN electromagnetic field calculation method can intuitively see the form of electromagnetic field movement and the form of alloy solution being stirred, which is impossible for any other company

3. Our company has the calculation software of electromagnetic force of electromagnetic stirrer, which can quickly and accurately calculate the electromagnetic force under different frequencies and currents, so as to provide users with more accurate optimal mixing current and frequency

4. Careful material selection 1) the selection of the electromagnetic wire of the agitator is the core issue to ensure the quality of the electromagnetic agitator. According to our years of production practice and the follow-up investigation on the production site of the electromagnetic wire factory, the selection of the electromagnetic wire should strictly grasp the wire material, the quality of the imported polyimide fluororesin composite film, the performance of the sintering equipment and the determination of the sintering process parameters. 2) The insulation paint adopts the waterproof solvent-free paint made of imported materials specially for the electromagnetic mixer. The paint film has strong adhesion, good integrity and slow insulation resistance attenuation, which effectively protects the insulation of the electromagnetic wire and extends the service life of the mixer. 3) Heat shrinkable pipes and waterproof sealants are imported from the United States and Japan. 4) The terminal block adopts a new structure and polytetrafluoroethylene high temperature resistant and high-strength material. The formed surface is activated with a special formula to improve its surface adhesion

5. Strong production capacity, advanced equipment and perfect process equipment

6. Advanced technology 1) adopt advanced vacuum drying and vacuum pressure impregnation technology to make the insulating paint have good filling performance and complete paint film. 2) A new hot pressing process is adopted to prevent damage to the insulation of the conductor. 3) Adopt advanced winding technology to improve the insulation performance and cooling effect of the coil

7. Advanced detection means and perfect quality assurance system 1) key detection equipment are imported advanced equipment, such as three-dimensional magnetic field tester, infrared thermometer, insulation resistance tester, low-frequency oscilloscope and dual digital multimeter, etc. 2) strict quality requirements are put forward for the electromagnetic wire factory, and personnel are sent to track and inspect. 3) The factory reexamination of the whole coil of wires: it is required that the insulation performance of polyimide film sintered wires does not change significantly after soaking and boiling in a constant temperature water bath at 90 ℃± 1 ℃ for 7 weeks. 4) Insulation test of single coil. 5) Insulation test of the whole machine before and after painting. 6) Hydraulic insulation test of the whole machine

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