RU57654U1 - CASTING AND ROLLING UNIT - Google Patents

Abstract

The invention relates to ferrous and non-ferrous metallurgy, namely to a casting and rolling unit for the simultaneous production of sheet metal and high-quality billets. The method includes a casting and rolling unit with a mold of internal variable cross-section, rectangular sections of which have different thicknesses. At least one of the sections has a thickness equal to (20-50) the thicknesses of thinner sections. The unit makes it possible to provide continuously cast billets for rolling mills for various purposes - billet, high-quality and strip. 1 ... 2 p. Formulas. 4il.

Description

The invention relates to ferrous and non-ferrous metallurgy, and more specifically to a casting and rolling unit for the simultaneous production of sheet metal and high-quality billets.

Known units for casting and subsequent rolling of ingots of variable cross-section (see US patent No. 3747667, NKI 164-282, MKI B 22 d 11/12). The mold is made with a cavity in the form of a circle segment, the design of the secondary cooling device is the same. Rolling stands carry out the compression of the ingot in the form of a segment. However, with such a deformation, the condition of equality of the drawing coefficients across the ingot width is violated. In view of this, the quality of the metal is low; significant is the amount of marriage due to the waviness of the edges of the rolled products or the warping of its central zone. In addition, with a small thickness of the ingot and a small thickness of the cavity of the mold, it is not possible to cast metal to the meniscus level, which leads to a deterioration in the quality of the ingot.

The closest analogue of this invention is an aggregate according to French patent No. 2085327, MKI B 22 d 11/00. 1972 The unit includes a mold consisting of two parts located on the carriage and two independent secondary cooling systems. It also includes rolling stands for deforming rectangular ingots. Such an aggregate has the advantage that it makes it possible to cast simultaneously both strips of small thickness, for example 2-8 mm, and high-quality billets - square sections from 150 × 150 mm to 200 × 200 mm, rectangular 150 × 250 mm, etc. For many plants, this is desirable. However, when casting thin strips and in this

In this case, it is impossible to cast metal to the meniscus level and to achieve high quality strips.

This invention is aimed at solving the technical problem: to ensure the improvement of the quality of thin metal strips while expanding the technological capabilities of the unit - the ability to simultaneously produce sheet metal and high-quality billets.

This problem is solved due to the fact that the mold formed by the water-cooled roll and the segment is made with rectangular sections of various thicknesses, of which at least one is made with a thickness equal to (20-50) thicknesses of thinner sections; beneath the mold, there are devices for separating the ingot into parts of various thicknesses in the form of stops and roller systems, and behind them are rolling stands in the form of several continuous lines for rolling thin sections of the ingot and separately for rolling its thickened part. In addition, the secondary cooling system is installed under the mold only in the area of the greater thickness of the mold cavity. For thinner areas of secondary cooling is not provided.

It is these differences that provide a solution to the technical problem, since the use of a mold in the form of a roll and a segment with rectangular sections of various thicknesses, including at least one thickness equal to (20-50) thicknesses of thinner sections, makes it possible to install a funnel in a section of a larger thickness for supplying liquid metal under the level with the protection of the meniscus with a layer of slag or exothermic mixture, which will provide a significant increase in the quality of the ingot, and its entire volume, since ivaetsya meniscus protection in all areas of the mold cavity cross-section, and thick and thin. Under the mold, stops and roller systems separate sections of the ingot of smaller thickness and further

various rolling stands carry out compression of sections of the ingot of various thicknesses.

Between the distinguishing features and the solution of the technical problem there is a direct causal relationship. These features provide the possibility of obtaining from a single heat and sheet metal, and high-quality billets.

The design is illustrated by drawings (figure 1 - figure 4), while figure 1 shows a General view of the unit, figure 2 is a section along the plane AA, and figure 3 is a section along the plane BB. Figure 4 shows a perspective view of the shape of the obtained ingot.

The following notation is accepted. The ladle for liquid metal 1 is located above the intermediate ladle 2, from which through the funnel 3 the liquid metal enters the mold formed by a water-cooled roll (rotor) 4 (with the inner (working) wall 24) and segment 5 (with the inner (working) wall 25) .

The ingot consists of sections of a rectangular or square section of a high-quality ingot 6 and sections of sheet metal 7. Thin sheets are separated sharply from a thick section of an ingot of rectangular or square section and they are fed to rollers 8 and two-roll stands 9 and 10 after stripping the side faces into in the process of moving through the unit 11, the sheets are rolled in four-roll stands 12 and wound into rolls 13. The rectangular or square section is unbent using the stop 14 and rollers 15. The cleaning unit 16 It is used for stripping the side faces (in the sections of cutting thin sheets).

After that, the ingot is cut with flying scissors 17, and the workpieces 18 are fed to the high-quality mill in the form of stands with a horizontal arrangement of rolls 19 and with vertical rolls 20, or to a universal rolling stand, or to heating furnaces, or to a production warehouse.

Casting is carried out with the protection of the meniscus of the liquid metal with a layer of slag or exothermic mixture 21 supplied through the tray 22 from the feeder 23.

The unit operates as follows. Liquid metal is delivered to the unit in a lined ladle 1 and this metal is poured into the intermediate ladle 2, and from it through a funnel 3 under the meniscus level in the mold. The mold formed by the roll 4 and segment 5 provides the formation of an ingot (see Fig. 4) at the edges in the form of sheets of thickness h, and in the center in the form of a rectangle of thickness H = (20-50) h and width (20-100) h ( see figure 1, 2).

After crystallization of the sheets of thickness h, they are separated from the rectangular ingot 6 and these sections of the thin sheet metal 7 enter the rollers 8, stands 9 and 10 to the stripping machine 11, which performs a continuous cleaning of the cut-off zone of the sheets 7 when they are separated from the rectangular section of the ingot 6. When defects 11, the machine 11 can also remove them from the wide surface of the sheets 7. After stripping, the sheets 7 of thickness h are rolled in four-roll stands 12 and coiled by a coiler 13.

The rectangular section of the ingot of thickness H = (20-50) h is separated from the roll 4 by means of an abutment 14 and fed to the cleaning machine 16 by rollers 15. This machine provides a continuous cleaning of sections of the side surfaces that were connected to sections of thin sheets during casting, and then the ingot 6 is cut into measured lengths with flying scissors 17. The cut billets 18 are fed to the high-quality or harvesting mill in the form of alternating stands with a horizontal arrangement of rolls 19 and with their vertical arrangement 20. You can also use mills of a different design: pendulum, planetary, or continuous forging units with double-sided compression. You can feed the ingot 6 to the high-grade mill and without cutting it with scissors 17.

If you need a commercial cast billet of square or rectangular cross section, the billet 18 is served on the refrigerator and then to the warehouse.

This casting and rolling unit provides the following advantages:

- firstly, it makes it possible to obtain both sheet metal and high-quality billet from one heat;

- secondly, it makes it possible to significantly improve the quality of the metal through the use of its casting “under the level” with the protection of the meniscus by slag (or exothermic) mixtures.

In the cavity of the mold formed by parts 4 and 5, there is a funnel 3 connected to the intermediate bucket 2 (Fig. 3). The end of the funnel 3 is immersed in the liquid metal so that the stream of metal is protected from oxidation. The liquid metal meniscus is protected by a layer of slag mixture 21 both from oxidation and from undercooling (undercooling), which dramatically reduces the number of defects such as folds, inversions, and transverse cracks.

The slag mixture is fed through the tray 22 from the feeder 23, for example, periodically (the mixture can be supplied, for example, using a device according to the USSR author's certificate No. 1695113 - “Device for feeding slag and exothermic mixtures to the crystallizer.” Invention Bulletin 1991. No. 45. S.43).

The slag mixture is partially melted and its layer 21 (figure 3) protects the entire surface of the meniscus: not only sections 7 of thickness h, but also of section 6 of thickness H = (20-50) h (figure 4). It is known that the supply of slag mixtures to the meniscus leads to the fact that part of the mixture is melted and its thin layer forms a skull on the side surface of the ingot, playing the role of a lubricant between the surfaces of the ingot and the mold. This 1.5-2.0 times reduces the friction forces and mold wear (see M. Brovman,

Marchenko I.K., Cannes Yu.E., Ivanov V.I. Improving the technology and equipment of continuous casting machines. - Kiev: Technique. 1976 .-- 165 s.).

During continuous casting with meniscus protection by slag mixtures, a very high quality of metal is ensured, and the molds do not fail due to wear, as is the case with "open spray" casting, i.e. without meniscus protection.

Only by using casting technology to the meniscus level was it possible to provide continuous casting of high-quality steels for the production of pipes, rails, beams, sheet steel for the automotive industry.

But it is impossible to use such a technology for continuous casting of thin sheets with a thickness of less than 10 mm, because with such a small cross-section of the mold it is impossible to place a funnel 3 in it to supply metal “below the meniscus level”. Such a funnel requires, depending on its design, the thickness of the mold cavity of at least 60-80 mm. Sometimes these funnels perform not round, but elliptical (oval) cross-sections, so that they can be placed in a narrow gap, but at the same time, the funnel cannot be immersed in a mold with a cavity 10 mm thick.

The proposed unit provides the ability to cast with the protection of the meniscus, i.e. with high quality, thin sheets with a thickness of h = 2-5 mm and less, having a funnel in that part of the mold of rectangular cross section, which has a thickness of H = (20-50) h.

Now, for the production of sheet metal in continuous roll mills combined with rolling mills, thin ingots with thicknesses h = 2-5 mm are required and this is precisely the thickness of the mold cavities in sections 6 (Fig. 4).

The value H = (20-50) h for ingots of minimum thickness h = 2 mm is H = 40-100 mm, and for thickness h = 5 mm it is H = 100-250 mm, which

provides the implementation of casting under the level with the location of the funnel in the mold.

Thus, at h = 2-5 mm, the thickness of the section of the mold of rectangular cross section of larger thickness N will be (2 ÷ 5) · (20 ÷ 50) = 40 ÷ 250 mm, and with such dimensions of the part of the section of the mold, a funnel for feeding metal can be placed in it under the meniscus level, for example, with a hole in the funnel 15-30 mm and with an outer diameter of the funnel (made of refractory materials) equal to 30-80 mm.

The implementation of the mold with a section of a larger thickness H of less than 20 h (where h is the thickness of the section of a smaller thickness) will lead to difficulties in supplying liquid metal, in particular, supplying metal “below the meniscus level”, will complicate the protection of the meniscus with slag mixtures. The implementation of a section of a greater thickness of more than 50h will not give any advantages, but will only lead to an increase in the length of the liquid phase in this section, to the need to keep the strip peel from bloating at the outlet of the unit with the use of additional devices, to difficulties in operation and an increase in the cost of equipment.

The flow diagram of the molten metal from the funnel 3 to sections 7 is shown in FIGS. 2 and 3 by arrows. Thin sections of the ingot of thickness h solidify under conditions where there is a liquid metal replenishment from the side of an area of thickness H and the meniscus is protected from overcooling by a layer of slag mixture 21 (see FIG. 3).

Thus, with the proposed optimal thickness range H and h, all the advantages achieved by casting “to the level” are realized: reduction of metal oxidation, protection of the meniscus from hypothermia, reduction in the number of surface defects.

With the known designs of casting and rolling units, it is impossible to achieve these results for casting thin sheets (less than 5 mm thick). This design of the unit allows to obtain

these advantages, since the thin sections 7 of the ingot are protected by a slag mixture fed to the meniscus of section 6 with a thickness of H = (20-50) h.

These thin sections 7 are separated by an emphasis 14 and rollers 8 from the thicker part of the ingot 6 even before its crystallization is completed and are rolled in stands 10, 12 and cleaned by machine 11.

A section of an ingot of thickness H is unbent and, after completion of its crystallization, is subjected to stripping by machine 16, if necessary, cutting and then rolling on a high-quality or strip mill. In this particular example, the mold is made with two sections of thickness h and one thickness H (figure 4). Accordingly, the unit includes two rolling lines for rolling a thin sheet and one for rolling a thicker billet.

The sections of the ingot of small thickness h can be separated from the section of thickness H when they move “down” with respect to the thicker section of the ingot, as shown in FIG. But they can be separated by bending them in the direction of the upper surface of the thickened part of the ingot, as shown in figure 4. After separation of sections 7 (from the ingot section 6), they are unbent and fed after stripping to the rolling mill line.

The width of the mold cavity of section 6 is (20-100) h, which makes it possible, simultaneously with sheet metal, to obtain high-quality billets of square section with sizes from (20 × 20) h to (50 × 50) h and rectangular sections from (20 × 100 ) h with an aspect ratio of 1: 5 to (50 × 100) h with an aspect ratio of 1: 2. This makes it possible to provide continuously cast billets for rolling mills for various purposes - billet, high-quality and strip.

Claims (2)

1. A casting and rolling unit, including a funnel for supplying liquid metal under the meniscus level, a mold of internal variable cross-section, formed by a water-cooled roll and segment, a secondary cooling system, rolling stands, scissors and coilers, characterized in that the mold is made with rectangular sections of various thicknesses of which at least one is made with a thickness equal to (20-50) the thicknesses of thinner sections; under the mold, devices are installed for separating the ingot into parts of various thicknesses in the form of stops and roller systems, and behind them are rolling stands in the form of several lines for rolling thin sections of the ingot and separately for rolling its thickened part. 2. The casting and rolling unit according to claim 1, characterized in that the secondary cooling system in the form of water-air nozzles is installed under the mold only in the area of greater thickness of the internal cavity of the mold.