RU2002559C1 - Line of crystallizers for continuous-casting machine - Google Patents

Abstract

SUMMARY OF THE INVENTION: each of the CCM molds is mounted sequentially on the axis of the handle in the alignment of the subsequent mold and is equipped with a heat insulator made in the form of a strip placed on the working surface of the mold in such a way that half-planes bounded by the axis of the handle and passing through any point of the heat insulators in two neighboring molds do not match each other 14 un

Description

The invention relates to steelmaking, namely to the continuous casting of metals by the method of layer-by-layer growth of the cross-section of an ingot in successively mounted molds.

There is a known mold of a continuous casting machine mounted on the casting axis, into which molten metal is fed from a stationary intermediate tank through a casting cup inserted into the mold below the level of the molten well of the formed ingot (see Continuous casting of steel: From the experience of the Azovstal plant on improving techno - logics of continuous casting of steel / Aut.col .: V.V. Leporsky, D.A. Dyukin, O.V. Nosochenko, etc. - Donetsk, Donbass, 1982.p. 24-29). A disadvantage of the known crystallizer is the limited heat removal from the liquid metal side through the solid crust of the ingot to the walls of the crystallizer as the crystallization front advances to the core of the ingot. This leads to a decrease in the productivity of the whole complex of the casting process, an increase in the technological length of the machine due to the secondary cooling zone, and also to a decrease in the quality of the ingot due to the low crystallization rate of the metal in the central regions of the cross section of the workpiece.

Also known is the crystallizer assembly of a continuous casting machine for bi-metal billets, in which a crystallizer forming the core of the continuously cast ingot is mounted above the mold forming its shell (see French Patent No. 1296729, cl, B 22 D). A disadvantage of the design of the known crystallizer assembly is the difficulty of supplying liquid metal to the second mold, which requires the presence of additional intermediate containers for the liquid metal of the casing, as well as an additional number of casting nozzles located around the perimeter of the mold. Moreover, in the production of large bimetallic billets, the use of two crystallizers does not provide high rates of crystallization of metals, and therefore, retains the inherent disadvantages of this factor as described above.

Also known is the assembly of molds of continuous casting machines, adopted for the prototype, in which molten metal is fed into molds successively placed along the casting axis with a discretely increasing cross section 1. The known design of the assembly of casting machines provides

an increase in the productivity of crystallization processes due to layer-by-layer cross-sectional formation of a continuously cast ingot, however, it requires the supply of liquid metal to the target of each mold. At the same time, the design of the intermediate tank is complicated, the need arises to place numerous devices for regulating the pressure of the molten metal, monitoring the level of the bath of molten metal in each mold, which significantly complicates the design of the assembly as a whole and its operation, reduces the reliability of the continuous casting machine and makes it difficult to maintain.

The aim of the invention is to simplify the design of the assembly by simplifying the supply of molten metal to the mold.

For this purpose, in the mold assembly of the continuous casting machine, comprising successively placed molds with a discretely increasing cross-section, according to the invention, each of the molds, with the exception of the latter, is installed in the alignment of the working cavity of the subsequent mold and is equipped with an insulator made in the form of at least one strip fixed on the working surface of the mold parallel to the axis of the stream so that the half-planes bounded by the axis of the stream and passing through any point in heat - tori in two adjacent molds do not coincide with each other.

As is known, in order to increase the productivity of crystallization processes during continuous casting of metals, the technology of layer-by-layer formation of an ingot is used, the essence of which is to supply liquid metal to crystallizers with a discretely increasing cross section, which are sequentially installed along the axis of the handle. One of the serious problems in the implementation of this technology is that the supply of liquid metal is necessary in the working cavity of each mold. Known methods for supplying liquid metal to molds, borrowed from the technology of continuous casting of metals into one mold, cannot be used for layer-by-layer formation of an ingot for the following reasons,

Due to the limited free space in the immediate vicinity of the continuous casting machine, it is not possible to place intermediate tanks for liquid metal with a number equal to the number of molds near the technological axis of the machine. Placement of intermediate tanks away from

crystallizers require lengthening of thermally insulated, hermetically sealed troughs, the operation of which is laborious. Moreover, the use of several intermediate tanks poses the problem of timely replenishment of them with liquid metal. The supply of metal to intermediate tanks installed at different levels of the machine near the molds further complicates this process operation.

The control over the level of liquid metal in the molds and the regulation of its flow rate from the intermediate tanks are substantially complicated. In addition to a multiple increase in the number of regulating and controlling means, the use of an external supply of metal to the crystallizers through intermediate vessels requires an additional system of mutually coordinated functioning of these means.

It is necessary to take into account the difficult-to-realize supply of liquid metal directly to the barrel of crystallizers installed one above the other, since the space for placing the casting glasses is limited by the width of the ingot layer to be stacked, i.e. 30 ... 60 mm. It must be borne in mind that for the normal filling of the working space of crystallizers, it is necessary to supply liquid metal simultaneously to several points along the perimeter of each mold.

Thus, the supply of molten metal to the barrel of series-mounted molds by known methods and means when implementing the technology of layer-by-layer formation of an ingot significantly complicates the design of the mold assembly, its operation and maintenance.

In contrast to the known liquid metal supply methods, the proposed design of the crystallizer assembly provides for the installation of each mold, with the exception of the latter, in the meniscus of the working cavity of the subsequent mold, which seals the target of all molds, except the first. Therefore, this feature deprives the design of the site of the possibility of external supply of liquid metal to the target of sealed crystallizers.

However, the target of the first mold remains free, the flow of liquid metal into which is not at all difficult. Therefore, in the claimed technical solution, the target of the first mold is used to supply liquid metal to all other molds through the channels formed in the body of the formed ingot during crystallization of the individual layers. To form channels in the body

each mold is equipped with a heat insulator made in the form of a strip fixed on the working surface of the mold parallel to the casting axis. The heat insulators installed in this way exclude the crystallization of the growing layer at the place of contact of the liquid metal with the heat insulator, and that formed from the hole, a depth equal to the height of the mold, filled with liquid metal poured into this mold, is a channel for transferring liquid metal to all subsequent crystallizers. An exception is the last mold during casting that is not equipped with a heat insulator. The layer formed therein is the outer layer of the preform, the crystallization of which along the perimeter of the cross section of the preform must be continuous.

For continuous crystallization of the preform, it is necessary that the non-crystallized cavity of the channels in each layer of the ingot, after feeding the molten metal into the subsequent crystallizer, is intensively frozen. This effect occurs if the channels formed in the ingot in adjacent molds do not fit together. Given that the position of the channels uniquely determines

Since the position of the heat insulators fixed on the walls of the molds, the channels will not overlap in adjacent layers of the ingot if the half-planes bounded by the axis of the machine handle and passing through any point of the heat insulators in two adjacent molds do not coincide with each other.

As a result of patent information research, the absence of known technical solutions with input distinctive features was established, therefore, the proposed technical solution meets the criterion of significant differences,

In FIG. 1 shows an axial section of a caster mold assembly; figure 2-5 cross-sectional views of each of the molds; figure 6 presents a diagram of the crystallization of metal in the longitudinal section of the ingot; Figures 7-14 are a diagram of the crystallization of metal in cross sections of the formed ingot.

The mold assembly includes casting axially mounted in series

1 crystallizers 2-5 with a discretely increasing cross section. Each of the molds 2-4 is located in the alignment of the working cavity of the subsequent mold, which together with the last mold 5 form a single working cavity of the unit, sealed on the side of the side walls. Each of the molds 2-4 is equipped with a heat insulator made in the form of strips 6-8, mounted on the working surfaces of the molds parallel to the casting axis 1. The length of the heat insulator strip in each mold is equal to the height of its working surface. The strip b of the heat insulator is fixed on the right working wall of the mold 2. The strip 7 of the heat insulator is mounted on the left working wall of the mold 3, and the strip 8 of the heat insulator is installed on the right wall of the mold 4. The working surface of the mold 5, installed last during casting, is the heat insulator does not have a torus.

The process of continuous casting of metals in a continuous casting machine with the crystallizer assembly shown in FIG. 1-5 are carried out as follows.

The liquid metal 8 (FIG. 6) is continuously fed from the intermediate ladle 9 through the casting nozzle 10 into the working cavity of the mold 2. In contact with the heat-conducting sections of the working surface of the mold 2 (FIG. 7), the liquid metal crystallizes to form a solid core core formed ingot. In contact with strip 6 of the heat insulator, crystallization of the liquid metal does not occur, and the solid core at this point has a gap. As the formed ingot moves along the axis of the stream, the crystallization front of the core closes (Fig. 8) with the exception of the region adjacent to the heat insulator 6. In this case, the cavity formed in the core body is a channel through which liquid metal replenishes the mold working space 3.

In the mold 3, the same processes occur as in the mold 2. In contact with the heat sink walls of the mold 3 (Fig. 9), a solid crust of the first ingot layer is formed, with the exception of the region adjacent to the heat insulator 7, the channel cavity formed by the heat insulator 6. in the mold 3, it loses contact with the heat insulator and, as the ingot moves, it is intensively frozen. As a result of this, at the exit from the crystallizer 3, a cross section

the ingot, with the exception of the region adjacent to the heat insulator 7, is subjected to through crystallization (Fig. 10). Through the channel formed, liquid metal from

mold 3 replenishes the working space of mold 4 (Fig. 6).

The design of the mold 4, similar to the design of the molds 2 and 3, determines the similarity occurring in them

crystallization processes. The channel cavity formed by the insulator 7 in the mold 4 is frozen (Fig. 11), but a channel is formed in the contact of the liquid metal with the insulator 8 (Fig. 12), through which replenishment

mold 5.

In the last mold 5, an outer layer of the ingot is formed. Convicted that the working surface of the mold 5 is not

provided with a heat insulator, a solid crust of the outer layer is formed around the entire perimeter of the mold (Fig. 13). After the crystallization fronts are closed, the cross section of the ingot is formed.

11 (FIG. 14) is completed.

As an example of a specific implementation of the claimed technical solution, a unit of four caster molds can be used for layer-by-layer formation of an ingot with a cross-sectional size of 300 x 1600 mm. The first three crystallizers along the casting with cross-sectional dimensions of 90 x

1300, 160 x 1400 and 230 x 1500 mm and a height of 1500 mm each are equipped with heat insulators made in the form of strips with a width of 50 mm, mounted alternately in the wide and narrow walls of the molds. The last mold with a cross-sectional dimension of 300 x 1600 mm does not have heat insulators,

These parameters of the caster crystallizer assembly provide a through crystal.

lysis of the ingot at the outlet of the last mold with a casting speed of up to 1.2 m / min. In this case, the liquid metal is supplied from one tundish with a capacity of 6.5 m3,

installed above the barrel of the first mold during casting, into which molten metal is fed through a submersible casting glass.

Thus, the totality is different. The inventive assembly of crystallizers makes it possible to achieve the set goal of the invention - to simplify the supply of liquid metal to the continuous casting molds, in layers

forming the cross section of the ingot.

(56) Hermann E. Continuous Casting, Moscow: Gostekhizdat, 1961, p. 324.

Formula A from Breteni

LINE OF CRYSTALIZERS OF THE CONTINUOUS PREPARATION MACHINE MACHINE, including molds successively placed along the axis of the handle with a discretely increasing cross-section, characterized in that, in order to simplify the process of supplying molten metal to the molds, each of kriFig .1.

molds is installed in the working cavity of the subsequent mold and, with the exception of the latter, is equipped with a heat insulator made in the form of at least one strip mounted on the mold working surface parallel to the axis of the handle, while the heat insulators of adjacent molds are located in the half-plane opposite to the axis of the handle x

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