What are the main models of continuous casting machine

The vertical continuous caster was the main model before the 1950s and 1960s. The molten steel pouring system, mold, cutting device, and billet outlet position of this continuous caster are all arranged on the vertical axis of the continuous caster, and the entire equipment occupies a large height space in the workshop.

During the production of the vertical continuous casting machine, the cast slab is solidified in the mold and the second cooling section. Due to the vertical arrangement, the non-metallic inclusions in the liquid metal are easy to float up, and the heat dissipation around the cast slab is relatively uniform, and the cast slab is being drawn During the process, it is not affected by other bending forces, and the resulting cast slab is of good quality and is not prone to cracks. Therefore, it is more suitable for the production of alloy steel and other steels that are sensitive to cracks.

However, this kind of continuous caster is too high, the investment in infrastructure and equipment is large, and maintenance is difficult. Because of the high-head casting, the lower section of the cast slab is prone to bulge deformation under the action of the hydrostatic pressure of the molten steel, so it is only suitable for use Production of cast billets with small cross-sections.

Vertical bending continuous caster is a transitional model developed on the basis of vertical continuous caster. Its upper part is the same as the vertical continuous casting machine. The difference is: the vertical bending continuous casting machine uses the top bending device to bend the casting billet by 90° after it is completely solidified, so that the casting billet is tapped and cut in the horizontal direction.

The vertical bending type continuous caster partly reduces the height of the whole machine, but because the cast slab is completely solidified and then top-bent, it is prone to defects such as cracks during production, and is mainly used for the production of small-section billets.

The arc continuous casting machine is the most widely used model in the world. Its crystallizer, secondary cooling section, billet straightening machine, etc. are all arranged on a 1/4 circle of the same radius. The cast billet is completely solidified within the 1/4 circle, and the horizontal tangent line must be straightened by a point and then be horizontal. Pull out in the direction, and then cut to length.

The full arc continuous casting machine is also called the single point straightening arc continuous windlass. The secondary cooling device of the mold of the full-arc continuous casting machine and the tension-straightening equipment are all arranged on a circle of 1/4 arc. The casting billet forms an arc in the mold, and moves along the arc track after being pulled out, and is cooled by spraying water until it is completely solidified. The fully solidified slab is straightened at the horizontal tangent point, then it is pulled out of the continuous casting machine and cut to length, and then output from the horizontal direction. The height of the continuous caster is basically equal to the radius of the arc. Usually the outer arc radius of the continuous casting machine is called the arc radius of the arc continuous casting machine.

Main advantage

1. Because it is arranged in the 1/4 arc range, its height is lower than that of the vertical type and the vertical bending type, the equipment is lighter, the investment cost is lower, and the equipment is easy to install and maintain, so it is widely used;
2. Due to the low height of the equipment, the slab bears relatively small hydrostatic pressure during the solidification process, which can reduce internal cracks and segregation caused by bulging deformation, which is beneficial to increase the drawing speed and improve the quality of the slab.

Main disadvantage

1. During the solidification process of molten steel, non-metallic inclusions tend to accumulate in the inner arc, which is easy to cause the defect that the inclusions on the inner arc side of the cast slab are enriched at about 1/4;
2. In order to prevent internal cracks, the billet is required to be completely solidified before straightening, which limits the increase in the drawing speed and affects the production capacity.

As the casting speed of the continuous caster increases, the slab cannot be completely solidified when it reaches the straightening point. When the slab with a liquid core is subjected to single-point straightening, due to the large deformation of the solid-liquid interface, cracks are likely to occur in the center of the slab defect.

Therefore, the multi-point straightening technology is used to disperse the total strain into the strain of each straightening point, so that the deformation rate of the solid-liquid interface of the slab is reduced. In this way, the cast blank can be straightened with a liquid core without internal cracks, which is beneficial to increase the drawing speed.

Straight mold arc continuous casting machine (straight arc continuous casting machine) adopts straight mold, the mold is equipped with a linear section of 2.5～3.5m down, and the casting billet with liquid core is gradually bent after passing through the linear section. In an arc shape, the subsequent process is exactly the same as that of a multi-point straightening arc continuous casting machine.

Main advantage

1. Retaining the advantages of the vertical continuous caster, the molten steel in the straight mold and its lower straight section during the solidification process is conducive to the floating and uniform distribution of large inclusions in the molten steel. It avoids the defect of inclusions enrichment at 1/4 of the inner arc side of the cast slab, and has a significant effect on the production of high-clean steel;
2. Since the casting slab is gradually bent into an arc with a liquid core, it still has the advantages of lower equipment height and lower construction cost of the arc continuous casting machine.

Main disadvantage

The straight arc continuous casting machine has one more bending process, which increases the possibility of cracks on the outer arc side for crack-sensitive steels.

It should be said that the straight mold arc continuous casting machine is a new type of continuous casting machine that integrates the advantages of vertical and arc continuous casting machines. At present, more and more steel mills use this type of slab continuous casting machine, because It can better meet the quality requirements of cast slabs and improve production efficiency.