EP3623074A1 - Method for the preparation of long products which are close to final dimensions and a continuous casting and rolling installation for carrying out the method - Google Patents

Abstract

In a method for the production of long products close to the final dimensions, metal melt is passed from a metallurgical vessel for a respective casting strand (11, 12) through a spout and regulated by a control element (16) arranged thereon into a mold (21) of a continuous casting machine (20). The at least one cast strand (11, 12) is rolled into a rolling system (30) following the continuous casting machine with a number of roll stands (31) to produce these long products (13, 14). The molten metal is passed open into the mold (21) without a pouring tube immersed in it, and the casting strand (11, 12) is produced close to the final dimensions, each with a strand cross section, in particular less than 120x120 mm, and this at a casting speed, in particular between 4 and 12 m / min . In the subsequent rolling plant (30), a smaller number of rolling stands (31) are preferably used between 2 and 6 less than the standard. With this method, direct feeding of uncut casting strands into a subsequent rolling mill and casting and rolling close to the final dimensions are achieved in a compact casting and rolling plant.

Description

The invention relates to a method for the production of long products in particular according to the preamble of claim 1 or 2, and a casting and rolling system for carrying out the method according to the preamble of claim 7.

A steel mill according to the publication EP-A-3 052 259 comprises a continuous casting machine and a rolling mill, which is arranged in direct succession to the continuous casting machine. The latter is with at least two casting lines and the rolling mill is equipped with at least two separate rolling lines and, accordingly, separate rolling stands, which are arranged adjacent to one another along corresponding working directions, the installation comprising at least one single feed device, for example a distributor trough. A transfer path for the casting strands to the rolling mill is assigned, by means of which each of the casting lines is connected to a corresponding rolling line.

In this known system, it is further provided that it works in an endless process, in which the strands from the casting machine are optionally passed via the transfer path into an inductive heating system and from there directly to the rolling stands for an immediately following rolling. In the event of a malfunction, particularly in the rolling mill, a cutting device can be activated and the strands can be cut into sections of predetermined lengths.

The object of the invention is to further develop a process for the production of long products or to improve this generic continuous casting installation and the associated rolling mill in such a way that a cost reduction in the casting operation and the rolling mill is achieved.

According to the invention, this object is achieved by the features of claim 1 or 2 or by the features of claim 7.

With this method according to the invention, a direct feeding of uncut casting strands into a subsequent rolling mill and the casting and rolling close to the final dimensions are achieved in a compact casting and rolling plant. To increase productivity, this compact casting and rolling system can also be operated with two or more casting strands which are fed directly into a two-core or multi-core compact rolling mill and rolled out to the corresponding finished cross-section. The pouring system is also equipped with special facilities for pouring the pouring jet into the mold to enable a higher pouring speed.

The casting and rolling system can be built much smaller than conventional systems. An energetic analysis shows that if a casting format is divided into two smaller casting formats and these formats are rolled at the same time in only one rolling mill, the necessary forming work can be reduced compared to the throughput-equivalent single-strand operation with a larger casting format. With this division into smaller formats, a further cost advantage is achieved through the significantly shorter construction.

With this method according to the invention, the rolling mill is very simplified, in that, in contrast to conventional billets or casting strands with dimensions of 130 x 130 mm or 150 x 150 mm, one or two or more casting strands cast close to the final dimensions directly, i.e. without dividing them, into a compact rolling mill fed and rolled out to the corresponding finished dimensions. The casting strand, which is cast close to the final dimensions, has a cross-sectional dimension, in particular of less than 100 x 100 mm; preferably dimensions between 50 x 50mm and 80 x 80mm. This makes it possible to save several rolling steps and to dispense with a conventional roughing mill.

In a two-strand or multi-strand system, the at least two casting strands running next to one another are fed into the rolling mill with a narrowing distance from one another in such a way that these at least two casting strands are rolled together in the same roll stand with a pair of rollers.

The pairs of rollers each form at least two calibrated openings on the outer surface of their rollers for a continuous strand. This means that, as in known rolling mills, it is not necessary to provide two rolling trains running independently of one another, but one rolling train can be used for a plurality of strands cast next to one another.

The casting strands are very advantageously rotated by a predetermined angle before entering the first pair of rolls of the rolling mill. This results in an optimal alignment of the strands for the rolling, in which the rollers of the pairs of rollers for receiving the twisted casting strands are each provided with an adapted, calibrated opening with a corresponding cross section.

Fig. 1

eine schematische Seitenansicht einer erfindungsgemässen Giesswalzanlage mit einer Stranggiessmaschine, und eines Walzwerks;

Fig. 2

eine schematische Draufsicht der Giesswalzanlage nach Fig. 1 mit der Stranggiessmaschine und dem Walzwerk;

Fig. 3

eine schematische Vorderansicht einer Führungs- und Richtrolle und des Querschnitts des Strangs; und

Fig. 4

eine schematische Vorderansicht eines erfindungsgemässen Walzgerüstes mit einem Walzenpaar und dem Querschnitt des Strangs.

Advantageously, the rolling mill is assigned a feed device, integrated in the guide and straightening rolls, of the at least two continuous casting line lines, by means of which the casting strands during casting, in particular when it is transferred directly from the casting to the rolling mill, by a certain angle inwards and after a certain distance around it Angles are bendable again in the casting or rolling direction, so that they are aligned for insertion into the openings of the pair of rolls of the first rolling unit. The invention and further advantages thereof are explained in more detail below on the basis of exemplary embodiments with reference to the drawing. It shows:

Fig. 1

a schematic side view of a casting and rolling plant according to the invention with a continuous casting machine, and a rolling mill;

Fig. 2

is a schematic plan view of the casting and rolling plant Fig. 1 with the continuous casting machine and the rolling mill;

Fig. 3

is a schematic front view of a guide and straightening roller and the cross section of the strand; and

Fig. 4

is a schematic front view of a rolling stand according to the invention with a pair of rollers and the cross section of the strand.

1 and 2 show a casting and rolling system 10 for the production of long metal products 13, 14, in particular steel products. The long products 13, 14 produced have a rectangular, square, polygonal or round cross-sectional profile as required. This continuous caster 10 is primarily suitable for the casting of billets with smaller formats between 50 x 50 mm and 120 x 120 mm, typically of 80 x 80 mm. It is poured at relatively fast casting speeds in the range from 4 to 12 m / min, preferably 5 to 8 m / min. Of course, other formats would also be suitable.

The casting and rolling system 10 comprises a continuous casting machine 20 with two adjacent casting strand lines for casting strands 11, 12 and a subsequent rolling mill 30 with a number of rolling stands 31, 32 arranged one behind the other, with pairs of rollers 33, 34, through which these casting strands 11, 12 are rolled into these long products 13, 14.

This continuous casting machine 20 with the two continuous casting lines running side by side is constructed per se in a conventional manner and is therefore not explained in detail below. A vessel 15 containing molten metal, which is a distributor vessel, is provided with a spout for each continuous casting line, a control element 16 adjoining the spout, preferably a slide closure or stopper, and a pouring jet protection 17. A water-cooled mold 21 is arranged below the pouring spout or this pouring jet protection 17 and forms a cavity which is formed with a cross section corresponding to the format of the strand produced to be cast.

The casting strands are assigned guide and support rollers 22 and pairs of straightening and support rollers 24, so that the casting strands 11, 12 guided through them are bent from the vertical with a radius, for example between 4 and 12 meters, and subsequently in an approximately horizontal direction along a horizontal one Level 25 are extendable to the rolling mill 30.

Furthermore, a cutting device 26 for separating the casting strands 11, 12 and a heating device, for example an inductive heating unit, are indicated after the guide and straightening rollers 24. Depending on the cross-section and casting parameters, the heating device could be dispensed with.

The rolling mill 30 consists of a number of rolling stands 31, 32 arranged one behind the other, each of which is equipped with rotating roller pairs 33, 34. This number of roll stands 31, 32 is usually between 12 and 18 stands. It comes with every rolling unit a reduction in the strand cross-section to the desired extent of the resulting long product 13, 14 causes.

This means that a smaller number of roll stands 31, preferably between 2 and 6 less than standard, can be used in this rolling mill 30 within the scope of the invention. In particular, this casting, which is close to the final dimensions, means that a so-called roughing road with a number of roll stands can be dispensed with.

With the method according to the invention, the two casting strands 11, 12 running next to one another are fed into the rolling mill 30 with a narrowing distance a such that these at least two casting strands 11, 12 are rolled by only one pair of rolls 33, 34 of the number of roll stands 31, 32 become. This distance a to be narrowed can be reduced, for example, from 800 mm to a distance a 'of 300 mm.

For this purpose, a feed device 29 is advantageously provided for the at least two continuous casting line lines, by means of which the casting line 11, 12, in particular when it is transferred directly from the casting to the rolling mill 30, by a certain angle inwards and after a certain distance by the same angle the casting or rolling direction are bent. This can be done, for example, by support and straightening rollers, which act laterally on the strands.

In addition, a twisting device 23 for the casting strands 11, 12 in front of the first pair of rolls 31 of the rolling installation can be provided for each casting strand line, by means of which the casting strands can each be rotated by a predetermined angle. Such a twisting device 23 can also be composed of support and straightening rollers. The Casting strands 11, 12 are of the in Fig. 3 shown position, in which they are arranged with respect to the horizontal plane 25 with their outer surfaces parallel or perpendicular thereto, rotated 45 ° in the longitudinal direction in their axis, so that they are then with their diagonals in this horizontal plane 25, as this in Fig. 4 is shown.

The feed device 29 and the twisting device 23 can also be combined into one unit, so that the two casting strands 11 and 12 leave the feed device already twisted by a certain angle.

In Fig. 3 In addition, guide and straightening rollers 24 are provided on a holder 27 in a conventional manner in the casting strand lines, through which the casting strands 11, 12 are positively guided, at least on their upper and lower sides.

According to Fig. 4 form the pairs of rollers 33, 34 which can be rotated via drives 37, 38 accordingly at least two calibrating openings 35, 36 on the outer jacket of their rollers 33, 34 for receiving one continuous strand 11, 12, respectively. The respective openings 35, 36 are provided with annular grooves in the Rollers formed, each having a triangular, rounded or other cross-section.

Within the scope of the invention, the continuous casting machine 20 has a control device (not shown in more detail) for controlling or regulating during the casting. Corresponding measuring means for the strands for determining the take-off speeds or for the strand profiles are arranged in such a way that their measurement results are evaluated by the control device and corrections are made if the two strands differ from one another. Sufficient withdrawal speeds of the casting strands 11, 12 are thus achieved ensured up to the rolling mill 30. The rolling speed is advantageously determined by the take-off speed.

It is therefore expedient to have at least one control or regulating device for the rolling speeds in the rolling mill 30 in conjunction with the casting speeds of the casting strands. These speeds are coordinated with each other.

In the event of a malfunction of the rolling mill 30 during the casting, the continuous casting machine 20 can continue to pour and the casting strands 11, 12 can be cut into definable lengths by means of the cutting device 26. Then there can be one in Fig. 2 indicated evacuation device 19 are activated to remove the cut strand sections. This is advantageously arranged in such a way that if the rolling mill fails, the cut strand sections 11 ', 12' are no longer conveyed into the feed device 29, but rather transversely thereto. In normal operation, the cutting heads 26 can be used to cut off the strand heads at the start of casting and the ends of the strand after the end of casting.

Following the finishing train 32, there is a removal device (not shown) for the rolling stock. This is advantageously carried out in such a way that a cutting device cuts the rolling stock to the final length of the rolling bars and these are then transported to a cooling bed for cooling and then bundled.

Since, according to the invention, primarily small formats are to be cast and rolled in order to reduce the necessary forming energy from the cast product to the rolled product, a new casting practice is provided for pouring the liquid metal from the distributor into the mold.

Classic open pouring, in which the pouring jet flows from a free-running nozzle from the distributor into the mold, is out of the question because the casting speed cannot be adequately controlled with this method, since it is very dependent on the fill level in the distributor. The known closed casting with an actuator for regulating the access of liquid into the mold and an immersion tube through which the melt is passed into the mold below the pouring level has the disadvantage that this process requires the pouring level to be covered with pouring slag. With the relatively small formats used here, the space in the mold is not sufficient for a sufficiently thick dip tube that would allow sufficiently long casting and rolling sequences, since the service life of the dip tubes is limited in time by the attack of the pouring slag.

It is envisaged that the respective pouring tube 17 ends when casting with its lower end above the bath level of the molten metal in the mold, preferably 20 to 50 mm, and thus does not dip into the bath in the mold. A flushing device, not shown, for the supply of inert gas, such as argon or nitrogen, can be provided, as a result of which the pouring jet can be surrounded by protective gas. The purpose of this is that a sealing gas screen surrounds the melt jet emerging from the pouring tube and flowing into the mold. This means that an oil known per se can be used for lubrication between the inner wall of the mold and the molten metal and consequently optimal conditions are created.

The metal supply from the distributor into the mold can be regulated with sufficient precision, as in the known closed casting, via an actuator, at the same time an inadmissible fanning out of the pouring jet subject to the regulation is prevented by the pouring tube. By The combination with a protected pouring jet and conventional oil lubrication removes a further limitation of closed pouring, which is that with very small pouring formats and high pouring speeds, the ratio of strand surface generated per unit of time and free bath surface area becomes very unfavorable (namely too large) and one sufficient melting of the casting powder to form slag can no longer be guaranteed. This limitation does not exist when lubricating with oil.

An advantage of the invention is the use of a rolling train which is connected to one or more, usually two, casting lines. In the case of a two-strand or multi-strand version, the inlet cross-section only has to be half as large for the same throughput of the rolling mill (at the same casting speed). This leads to significant advantages in the rolling process, in which considerable forming work can be saved in the rolling mill due to the casting cross-section which is closer to the final dimensions, and the number of roll stands required can be considerably reduced with the same throughput.

The relatively low rolling speed in relation to the cross section of the respective strand also allows the degree of deformation per rolling stand to be increased, and thus the number of rolling stands to be reduced.

The invention is adequately demonstrated with the illustrated exemplary embodiments. Of course, it could be illustrated by other variants. The spacing of the casting strands to be narrowed according to the invention could also be implemented in such a way that the one strand would be directed straight to the pair of rollers and only the other strand would be narrowed correspondingly more apart and these would then be guided together to the pairs of rollers. In theory, they could also be routed parallel to the rolling mill.

It is also possible to feed three or four adjacent casting strands with narrowing spacing into the rolling mill in such a way that they are rolled by the roll stands only by one pair of rolls, which are each provided with three or four calibrating openings for the strands to be rolled.

After the first rolling stand or a first group of rolling stands, the continuous casting lines can also be divided into two parallel, independent groups of rolling stands. In this case, on the one hand, the rolling speeds, which are considerably increased due to the already greatly reduced rolling cross section, can be controlled independently of one another in sections, and on the other hand, different finished dimensions can be rolled on the two lines.

Claims (17)

Method for producing long products, in which metal melt from a metallurgical vessel for a respective casting strand (11, 12) is poured through a spout and regulated by a regulating element (16), preferably a sliding closure or a stopper, into a mold (21) a continuous casting machine (20) and the at least one cast casting strand (11, 12) is rolled into a rolling system (30) following the continuous casting machine with a number of roll stands (31) to form these long products (13, 14), characterized in that
the molten metal flowing through the spout and regulated by the control element (16) is passed openly into the mold (21) without a pouring tube immersed in it, and the casting strand (11, 12) is close to the final dimensions, each with a strand cross-section, in particular of less than 120 × 120 mm and this is generated at a casting speed in particular between 4 and 12 m / min, and that in the subsequent rolling plant (30) a smaller number of rolling stands (31) are preferably used between 2 and 6 less than standard. Process for the production of long products preferably according to claim 1, in which by means of a continuous casting machine (20) at least two adjacent casting strands (11, 12) are cast and in a subsequent rolling plant (30) with a number of rolling stands (31, 32) arranged one behind the other Roller pairs (33, 34), these casting strands (11, 12) are rolled into these long products (13, 14), characterized in that
the at least two adjacent casting strands (11, 12) are rolled at least in the first of the roll stands (31, 32) with only a single pair of rolls (33, 34) per roll stand (31, 32). A method according to claim 2, characterized in that two, three or four adjacent casting strands with narrowing spacings are fed into the rolling mill in such a way that they are each rolled by the roll stands by only one pair of rolls, each with two, three or four Calibrated openings are provided, each of which form the defined cross section of the strand to be rolled. Method according to claim 2 or 3, characterized in that the casting strands (11, 12) are guided from the vertical in a radius and subsequently in an approximately horizontal direction to the same horizontal plane (25) to the rolling installation (30). Method according to one of claims 2 to 4, characterized in that
there is at least one control or regulating device for the rolling speeds in the rolling installation (30) in connection with the casting speeds of the casting strands. Method according to one of claims 2 to 5, characterized in that
the casting strands (11, 12) are rotated by a predetermined angle before entering the first pair of rollers (33, 34) of the rolling system (30), the rollers of the pair of rollers (33, 34) for receiving the twisted casting strands (11, 12) are each formed with an adapted, calibrated opening (35, 36) with a corresponding cross section with a diamond, square or similar shape. Casting and rolling system for carrying out the method according to one of claims 1 to 6, with a continuous casting machine (20) for at least two continuous casting lines running side by side and a subsequent rolling system (30) with a number of rolling stands with pairs of rollers arranged one behind the other, characterized in that in front of the rolling system ( 30) a feed device (29) of the at least two adjacent casting strand lines is provided, by means of which the casting strands (11, 12), in particular when they are transferred directly from the casting to the rolling system (30) by a certain angle inwards and after a certain distance the same angle can be bent again in the casting or rolling direction so that they are aligned for insertion into the openings (35, 36) of the roller pairs (33, 34) of the rolling stands (31, 32) arranged one behind the other. Casting-rolling plant according to claim 7, characterized in that the casting strand lines are assigned a plurality of guide and straightening rollers (24) or support rollers (22) in such an arrangement that the casting strands (11, 12) guided therein are from a vertical with a radius and subsequently are extendable to the rolling mill (30) by an approximately horizontal direction on a horizontal plane (25). Casting mill according to claim 7 or 8, characterized in that
for each of the casting strand lines there is a twisting device (23) integrated in the guide and straightening rollers (24) for the casting strands (11, 12) in front of the first pair of rollers (33, 34) of the rolling system (30), through which the respective casting strand ( 11, 12) can be rotated by a predetermined angle. Casting mill according to one of claims 7 to 9, characterized in that
The continuous casting machine (20) has a control device for achieving at least the same take-off speeds of the casting strands, suitable measuring means for determining the take-off speeds or the run profiles being used, the measurement results of which are evaluated by the control device and corrections of the take-off speeds to one another if the two strands deviate from one another be made. Casting mill according to one of claims 7 to 10, characterized in that
the continuous casting lines after the guide and straightening rollers (24) or supporting rollers (22) include a cutting device (26) for separating the casting strands (11, 12) and an evacuation device (19) for removing the cut strands (12 '), in particular in the event of a malfunction have in the rolling mill. Casting and rolling plant for carrying out the method according to one of claims 1 to 6, with a metallurgical vessel (15) with a spout for each continuous casting line, a control element (16) arranged thereon, preferably a slide closure or a stopper, and with a mold ( 21), each with a pouring tube (17) below of the control element (16), by means of which the molten metal is conducted into the mold (21), characterized in that the respective pouring tube (17) in the poured state, preferably with its lower end above the bath level of the molten metal in the mold (21) 20 to 50 mm, positioned and therefore not immersed in the bath. Casting mill according to claim 12, characterized in that
a purging device for the supply of inert gas, such as argon or nitrogen, surrounds the pouring tube (17) and / or the pouring jet, through which a gas screen sealing the metal jet emerging from the pouring tube is produced. Casting mill according to claim 12 or 13, characterized in that
An oil for lubrication can be supplied between the inner wall of the mold (21) and the molten metal in the cast state. Casting mill according to one of claims 7 to 14, characterized in that
two or more casting strands (11, 12) close together in separate molds (21), each with a regulating element for the steel inflow in the same, but can only be cast via an oscillating and extracting device. Casting mill according to one of claims 7 to 15, characterized in that
the rolling mill (30) is provided with a number of rolling stands due to the near-dimensional casting without a so-called roughing mill. Casting mill according to one of claims 7 to 15, characterized in that
that the casting strands (11, 12) can be conducted into at least one roll stand (31) each with only a single pair of rolls (33, 34) and subsequently the strands to be rolled can each be guided into separate roll stands, in which the strands can be rolled individually.

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