Vertical continuous caster
The vertical continuous caster is the main model before the 1950s-1960s. The steel pouring system, mold, cutting device and billet outlet position of the caster are all arranged on the vertical axis of the caster, and the whole equipment occupies a large space in the workshop.
During the production of the vertical continuous caster, the slab solidifies in the mold and secondary cooling section. Because of the vertical arrangement, the non-metallic inclusions in the liquid metal are easy to float up, the heat dissipation around the slab is relatively uniform, and the slab is not affected by other bending forces during the drawing process. The quality of the slab is good and it is not easy to crack, so it is more suitable for the production of alloy steel and other crack sensitive products steel grade of the sensor. However, the height of the caster is too high, the investment of infrastructure and equipment is large, and the maintenance is also difficult. Because of the high head casting, the lower section of the slab is prone to bulging deformation under the hydrostatic pressure of the molten steel, so it is only suitable for the production of small section slab.
Vertical bending caster
The vertical bending caster is a transitional type of caster developed on the basis of the vertical caster. The difference between the upper part and the vertical continuous caster is that the vertical bending continuous caster uses the top bending device to bend the slab 90°after it is completely solidified, so that the slab can be drawn out and cut in the horizontal direction. The vertical bending caster reduces the height of the whole machine in part, but because it is bent up after the slab is completely solidified, it is easy to crack and other defects in production, which is mainly used in the production of small section billet.
Arc caster
Arc caster is the most widely used type in the world. Its mold, secondary cooling section and billet straightener are all arranged on 1 / 4 circumference of the same radius. The billet is completely solidified in 1 / 4 circumference. After a point of straightening at the horizontal tangent line, it must be pulled out in the horizontal direction, and then cut to a certain length.
1. Full arc caster
Full arc continuous casting machine is also called single-point straightening arc anchor machine. The secondary cooling device of the mold and the tension straightening device of the full arc caster is all arranged on around 1 / 4 arc. The billets form an arc in the mold, move along the arc track after pulling out, and receive water spray cooling until complete solidification. After full solidification, the billet is straightened to the horizontal cutting point, and then the continuous casting machine is pulled out to cut into a fixed length, which is output from the horizontal direction. The height of the continuous caster is basically equal to the arc radius. Generally, the external arc radius of the continuous casting machine is called the arc radius of the arc continuous casting machine.
The main features of full arc caster are summarized as follows:
Main advantages:
(1) Because it is arranged in the range of 1 / 4 arc, its height is lower than the vertical and vertical bending type, the equipment quality is lighter, the investment cost is lower, the equipment installation and maintenance are convenient, so it is widely used;
(2) Because of the low height of the equipment, the static pressure on the billet during solidification is relatively small, which can reduce the internal crack and segregation caused by bulging deformation, and improve the casting speed and quality.
Main disadvantages:
(1) During the solidification process of molten steel, the non-metallic inclusions tend to accumulate in the inner arc, which is easy to form the defect of inclusions enrichment at about 1 / 4 of the side of the inner arc;
(2) In order to prevent internal crack, it is required that the slab should be completely solidified before straightening, which limits the improvement of drawing speed and affects the production capacity.
2. Multiple points straightening arc caster
The schematic diagram of multiple points straightening arc caster is shown in the figure below. With the increase of casting speed, the slab can't be completely solidified when it reaches the straightening point. When the slab with the liquid core is straightened at a single point, due to a large amount of solid-liquid interface deformation, the central area of the slab is prone to crack. Therefore, the multiple point straightening technology is used to disperse the total strain into the strain of each straightening point, so as to reduce the solid-liquid interface deformation rate. In this way, the billet can be straightened with a liquid core without internal cracks, which is conducive to improving the drawing speed.
3. Arc continuous caster with direct mold
The straight mold arc caster (straight arc Caster) adopts the straight mold, which is equipped with a straight section of 2.5-3.5m below the mold. After the straight section, the slab with the liquid core is gradually bent into an arc, and the subsequent process is exactly the same as that of the multiple point straightening arc caster.
Main advantages:
(1) The advantages of the vertical continuous caster are retained. During the solidification process of molten steel in the straight mold and its lower straight section, it is beneficial to the floatation and uniform distribution of large inclusions in the molten steel. The defect of inclusion enrichment at 1 / 4 of the inner arc side of the slab is avoided, and the effect of high-purity steel production is obvious;
(2) Because the billet is curved into an arc with liquid core, it still has the advantages of low equipment height and low construction cost.
Main disadvantages: the straight arc caster has one more bending process, which increases the possibility of cracks on the outer arc side for crack sensitive steel.
It should be said that the straight mold arc caster is a new type of caster integrating the advantages of vertical and arc caster. At present, more and more slab casters in steel plants adopt this type of caster, because it can better meet the requirements of slab quality and improve production efficiency.
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