Publish Time: 2022-06-24 Origin: Site
The production process of continuously casting high-temperature molten steel into a slab with a certain cross-sectional shape and a certain size is called continuous steel casting.
The equipment required to complete this process is called continuous casting equipment. The electromechanical-hydraulic integration of casting equipment, continuous casting machine body equipment, cutting area equipment, dummy bar collection and conveying equipment constitutes the core equipment of continuous steel casting, which is customarily called continuous casting machine.
A modern steelmaking plant is a combination of various metallurgical units. After the molten steel is refined outside the furnace, it is poured into a continuous casting machine to solidify it into a billet. The continuous casting machine is an important link between the flashing steel and the rolling steel. The solidification of the molten steel in the continuous casting machine is affected by the interaction of various physical processes such as heat transfer, mass transfer and stress. The comprehensive effect of this effect will determine Production efficiency and strand quality of continuous casters.
Continuous casting machines can be classified in various forms:
1. Classification by structure and shape
Vertical caster, vertical bend caster, vertical bend caster with multi-point bending, arc caster with straight sections, arc caster, multi-radius oval caster and horizontal caster machine. With the development of continuous casting technology, the research on wheeled continuous casting machine, especially thin slab continuous casting machine, has been carried out.
2. According to the section size and shape of the continuous casting machine pouring
Continuous casting machine can be divided into slab continuous casting machine, billet continuous casting machine, bloom continuous casting machine, round billet continuous casting machine, special-shaped section continuous casting machine and thin slab continuous casting machine.
In the billet continuous casting machine, the rectangular billet continuous casting machine is also included. Usually the casting section or the equivalent cross-sectional area is more than 200mmX 200mm or more is called the bloom, and the section or the equivalent section is less than 160mmX160mm. The billet is called a billet. Rectangular blanks larger than 3 are called slabs.
3. If the continuous casting machine is distinguished by the number of strands that can be cast under a common tundish, it can be divided into single-strand, double-strand or multi-strand continuous casting machines.
4. On one continuous casting machine, according to production requirements, a continuous casting machine that can cast slabs and simultaneously cast several strands of billets is called Fang, slab composite continuous casting machine or simply compound continuous casting machine.
Modern continuous casting machines are developing towards high productivity and high quality. Improving the breaking speed and shortening the auxiliary time is an important means to improve productivity.
Due to the high pulling speed, the length of the damaged liquid core in continuous casting increases, which causes a series of problems, such as the thinning of the thickness of the damaged shell after the mold is cast, the casting failure of the secondary cooling section is prone to bulging deformation, and due to straightening The casting billet still has a liquid core and internal cracks occur. The solution of these problems has become an important structural feature of modern continuous casting machines.
In order to protect the pouring, it is necessary to use a long nozzle and a ladle turntable with a lifting mechanism.
In order to improve the cooling effect of the mold and increase the thickness of the shell at the outlet of the mold, a straight long mold must be used. The mold vibration mechanism with a length of 900mm adopts a four-eccentric mechanism. The vibration adopts high frequency and small amplitude to reduce the depth of vibration marks and improve the The surface quality of the slab, the highest vibration frequency has reached 400 times/min.
Due to the high pulling speed and the lengthening of the liquid core, the billet is easily deformed by bulging, which affects the quality of the billet. The pinch rolls in the secondary cooling section adopt small roll spacing and high rigidity. structure.
The straightening of casting damage adopts multi-point straightening or continuous straightening to reduce the stress level in the bad shell due to straightening, prevent internal cracks and improve the quality. Compression casting technology is also an important way to solve this problem.
The height of the continuous casting machine is related to the type of the continuous casting machine.
The height of the vertical continuous casting machine refers to the distance from the upper mouth of the mold to the underground transport roller table, including: the length of the mold, the length of the secondary cooling zone, the synchronous cutting stroke, the length of fixed length and the height of the underground transport roller table Sum. When pouring 100x100~
When the 300x300mm square is broken, its total height is about 17~30m. Because the vertical continuous casting machine requires that the casting damage must be completely solidified at the cutting point, otherwise a major accident will occur, that is to say, the distance from the liquid level of the mold to the cutting point must be greater than the metallurgical length, which is related to the drawing speed. It is proportional to the thickness of the slab, so the higher the pulling speed, the thicker the slab, the longer its metallurgical length, and the higher the height of the casting machine. Since the vertical continuous casting machine is an early model, it has been replaced by other models such as arcs except that the vertical caster is still used for casting some alloy steels.
The height of the arc continuous casting machine is the sum of the length of the mold, the radius of the arc, and the height of the straightening zone (for multi-point straightening or continuous straightening), generally about 10m.
For ultra-low-head models, due to the use of multi-stage continuous straightening or multi-point straightening, the arc radius is greatly reduced, and the overall height is also lower, and its height h<25H (H is the thickness of the cast failure).
For thin slab continuous casting machine, because the slab is very thin, the metallurgical length is short, and the total height is about 7m.