EP0593001B1 - Method and device for making hot-rolled strips or beams from continuously cast material - Google Patents

Abstract

In a method for the production of hot-rolled strips or sections from continuously cast feedstock in successive working steps in a finishing train, in which the feedstock continuously cast in one or more casting machines is cut into lengths after solidification and the lengths first of all being heated in a heating zone (3a,3b) to rolling temperature as they pass through a soaking furnace and then transferred to a buffer zone (4a, 4b) and then into a temporary storage zone (5), from where they are transferred to the finishing train (8), in which they are finish-rolled, a significant shortening of the furnace system used can be achieved by the fact that strand lengths are transferred from the buffer zone into a shuttle (6a, 6b) and transferred transversely by the latter out of the casting line (x) into the rolling line (y), where they are conveyed longitudinally in the opposite direction to that in which the continuously cast feedstock is conveyed, using a temporary storage furnace arranged in the rolling line next to the soaking furnace and, after being fetched from the temporary storage furnace are introduced via a [lacuna] and, in some cases, via a holding furnace (7) arranged ahead of the rolling train, into the rolling train, where they are finish-rolled to give the end product. <IMAGE>

Description

The invention relates to a method and a plant for the production of hot-rolled strips or profiles from continuous, continuously cast primary material in successive steps of a finishing train, wherein the continuously cast primary material in one or more casting machines, after solidification, is divided into extrudates and the extrudates are passed through a compensating furnace in one The heating zone is heated to the rolling temperature, then into a buffer zone and then into a storage zone and from there into the finishing train, where it is finish-rolled.

In modern CSP production plants, continuously cast thin slabs are used as raw material for the finishing train, which for example have a thickness of less than 70 mm, preferably 50 mm. The thin slabs are separated from an endless cast strand produced in a continuous casting machine, each with a length that corresponds to the required coil weight for the finished hot wide strip. The casting speed of continuous casting machines for thin slab continuous casting is relatively slow, while the feeding speed an assigned continuous hot strip mill is approximately 2 to 4 times higher. It is therefore advantageous to assign at least two casting machines to a continuous finishing train in such a way that thin slabs are alternately separated from each of the two endless casting strands and then each fed to the finishing train for rolling. With the help of, for example, two longitudinal / transverse / longitudinal transport systems, so-called ferries, the thin slabs are brought out of the respective casting line into alignment with the hot strip mill so that they can then be drawn into this. In a known version of such systems, it has two single-strand CSP casting machines, each with a compensating furnace and a ferry, and a common holding furnace in front of the CSP roller train for both strands. A heating zone, a system buffer and a storage furnace part are arranged in succession in each compensation furnace. In the heating zone, the thin slabs are heated to the rolling temperature. The subsequent system buffer is required in order to bridge the transport time required for alternating transverse transport of the thin slabs from both casting machines into the roller mill. The storage furnace creates the possibility of bridging limited downtimes of the roll train, for example caused by roll changes or malfunctions, with continuous cast strand production.

In such a system, the thickness of the thin slab is 50 mm, the width is 1550 mm, for example Length of the thin slab 44 m, the casting speed 5.5 m / min. and the feed speed of the continuous hot-rolled strip finishing train 0.29 m / s corresponding to 17.4 m / min. The feed speed is 3.2 times higher than the casting speed. the length of the heating zone is approx. 40 m, the length of the system buffer and the storage furnace part are approx. 105 m, the length of the ferry 49 m and the length of the holding furnace 49 m. In the CSP system, which is taken as an example, this results in a length of the furnace system of approximately 147 m and including the ferries of 194 m and, together with the holding furnace arranged in front of the roller train, a total length of 245 m. A system of this length is extremely expensive and requires a comparatively large amount of space.

To avoid these disadvantages, a system concept for the production of steel strip according to EP 0 413 169 A1 has been proposed. In order to reduce the investment costs and the space requirement and to improve the temperature control, the known finishing mill is arranged opposite to the direction of discharge of the steel strip caster with a lateral offset, whereby in addition to the compensation furnaces in the direction of discharge of the steel strip caster, a centrally arranged temperature compensation furnace is provided, which conveys towards the finish rolling mill, and the three Compensating furnaces lying next to each other in parallel are connected by an end-side transverse transport device.

The disadvantage of the one-time reversal of the transport direction of the thin slabs results in very different dwell times from the beginning and end of the thin slabs in the compensating furnace and thus unfavorable temperature distributions over the length of the thin slab. Another disadvantage of the known system concept results from the fact that the furnace system has to be passed under the casting system.

DE-A-4 017 928 discloses a process for the production of hot-rolled strips or profiles from continuously cast primary material in successive steps of a self-contained process chain, wherein the continuously cast primary material after solidification divides into individual strand pieces of a predetermined length, these in one Compensation furnace is heated to the rolling temperature and then rolled out to predetermined final dimensions, with a strand piece resulting from the continuous casting process being introduced into a buffer section of the compensation furnace to bridge a comparatively short, for example 10-minute interruption in the rolling process. In order to bridge a comparatively long interruption in the rolling process, the known method suggests that a starting material obtained in the continuous casting process is broken up into strand pieces of a predetermined length and the strand pieces are removed from the process chain using a furnace part designed as a ferry and thereby into a laterally parallel stopping line next to the The production line is extended, occasionally stored in a warming place and stacked in it and, after the interruption has been remedied, reintroduced into the process chain in the opposite direction.

It is disadvantageous that complex system parts are required to carry out this method, for example a furnace designed as a ferry with means for heating strand pieces, these means having to be designed so that they are also effective in a position of the furnace in the secondary line.

Based on this prior art, the invention has for its object to improve a method and a plant for the production of hot-rolled strips or profiles from continuously cast material of the type mentioned in the preamble of claim 1 and 2 to the effect that these avoid the aforementioned disadvantages and Difficulties have a comparatively short furnace system and thus a lower need for space and investment costs, the system should be suitable for bridging a comparatively long interruption of the rolling process in an uninterrupted casting process.

The object is achieved in a method according to the type mentioned in the preamble of claim 1 with the invention by the characterizing features in claim 1.

Another, also inventive solution to the problem is solved accordingly with the features of claim 2. Further refinements of the invention are in accordance with Subclaims provided.

Due to the fact that the strand piece is not stored in a storage furnace part located within the casting line, but instead is transferred in longitudinal transport opposite to the conveying direction of the continuously cast primary material, using a storage furnace arranged next to the compensating furnace in the rolling line, a compensating furnace used for this method can at least be moved around the length of the storage furnace part can be reduced from approx. 55 m, for example from a total length of 147 m to a total length of 92 m. This results in lower investment costs due to the smaller space requirement for the system, while avoiding the aforementioned disadvantages and difficulties.

A plant for the production of hot-rolled strips or profiles from endless continuously cast starting material in successive steps of a finishing train for carrying out the method according to the invention, comprising two CSP casting machines or casting lines according to the preamble of claim 4, is designed so that the formed as a memory Furnace part is arranged within the rolling line at a lateral distance next to the leveling furnaces of the casting lines.

Details, features and advantages of the invention result from the following explanation of the exemplary embodiments shown schematically in the drawings.

Fig. 1

eine CSP-Anlage mit zwei Gießmaschinen und nachgeordneten langgestreckten Ausgleichsöfen sowie mit einer zwischen den Gießlinien angeordneten, eine CSP-Walzenstraße aufweisenden Walzlinie,

Fig. 2

eine CSP-Anlage mit zwei parallelen Gießlinien mit verkürzten Ausgleichsöfen und einem in der Linie der CSP-Walzenstraße angeordneten Speicherofen,

Fig. 3

ein Arbeitsdiagramm der Anlage gemäß Fig. 2 in Form eines Weg/Zeit-Netzplanes.

Show it:

Fig. 1

a CSP system with two casting machines and downstream elongated equalizing furnaces as well as with a rolling line arranged between the casting lines and having a CSP roll train,

Fig. 2

a CSP system with two parallel casting lines with shortened equalizing furnaces and a storage furnace arranged in the line of the CSP roller mill,

Fig. 3

a working diagram of the system of FIG. 2 in the form of a path / time network plan.

The CSP system according to the prior art according to FIG. 1 has two identical casting lines (xx) and one rolling line (yy). In each casting line (xx) there is a casting machine (1a, 1b) and a pair of scissors (2a, 2b) arranged after it for dividing the casting strands into individual thin slabs. This is followed by a long furnace system, each with a heating zone (3a, 3b), a system buffer (4a, 4b) and a storage furnace (5a, 5b). In the example shown, the length of a heating zone (3) is approximately 40 m, the length of a system buffer (4) is also approximately 40 m and the length of a storage furnace part (5a, 5b) c. 67 m. Overall, the length of the two parallel equalization furnaces is approximately 147 m. A transverse transport device, each with a ferry (6a, 6b) with a length of approx. 49 m, is arranged downstream of these furnaces. Between the two pouring lines (xx) the rolling line (yy) with the holding furnace (7) of about 49 m in length, and the finishing train (8). The latter comprises three roughing stands and three finishing stands as well as a descaling device (9) on the feed side.

The CSP system designed according to the invention according to FIG. 2 has two shortened equalizing furnaces (3a, 4a; 3b, 4b) in the two casting lines (x-x), comprising only the heating zones (3a, 3b) and the buffer zones (4a, 4b). The length of a heating zone (3a, 3b) is approximately 40 m and a buffer zone (4a, 4b) is approximately 50 m. The length of a prior art furnace system is thus reduced from 147 m according to FIG. 1 to 92 m according to FIG. According to the invention, the furnace part (5) designed as a store is arranged within the rolling line (y-y) at a lateral distance next to the compensating furnaces (3a, 4a; 3b, 4b). Overall, the length of the system, measured from the shears (2a, 2b) to the end of the holding furnace (7), is reduced from 245 m to 190 m. The arrangement is such that the storage furnace part (5) extends approximately parallel to the heating and buffer zones (3a, 4a; 3b, 4b) of the compensation furnaces. As can also be seen from FIG. 2, with this layout of the system there is a further advantage of a system buffer (4a, 4b) extended from 40 m to approx. 50 m and a storage furnace (5) extended from 67 m to 80 m. With regard to the arrangement of the ferries (6a, 6b) and the holding furnace (7) and the finishing train (8), the system according to FIG. 2 is unchanged from the system according to FIG. 1.

An embodiment provides that in at least one of the casting lines (xx), advantageously in both additional storage furnace part (20a, 20b) can be arranged. With these additional furnace parts, the possible bridging time when the roller mill is at a standstill, for example as a result of roller change or malfunction, is extended by a casting length of approx. 50 m, ie by approx.

A path / time network location is shown in FIG. In the header with a total length of approx. 190 m are the heating zone (3), system buffer (4), the ferries (6a and 6b), the additional storage furnaces (20a and 20b) of the casting line (xx) as well as the storage furnace (5) and holding furnace (7) of the rolling line (yy) with the corresponding length information. The example shows two thin slabs (2a, 2b) at time zero at the end of the heating zones (3a and 3b) and two thin slabs (1a, 1b) within the system buffers (4a, 4b). At the time t = 70 s, the thin slabs (1a, 1b) advanced by 52.5 m into the ferries (6a, 6b) at a transport speed of 0.75 m / s. At time t = 110 s, the thin slab (1a) in the ferry (6a) entered the rolling line (yy) at a ferry speed of 0.25 m / s in 40 seconds from the casting line by 10 m, while the ferry ( 6b) remains unchanged in the second casting line (xx). At time t = 180 s, the thin slab (1a) was then transported from the ferry (6a) into the holding furnace (7) by a further 52.5 m. There, at time t = 220 s, after a further 30 m of conveying distance, it enters the roller mill (8). At a feed speed of 0.29 m / s, the thin slab (1a) passes through the Finishing line (8) in approx. 152 s. With a casting speed of approximately 0.1 m / s and the length of a thin slab of 44 m, the production of a 44 m long cast strand requires 440 s. Because one casting is continuously produced in two casting lines, a thin slab (1a, 1b) is available in a staggered cycle sequence of 220 s. Between a total rolling time of 152 s and a production time of 220 s for each thin slab, there is a mathematical pause of approx. 68 s after each rolling cycle of 152 s. This results in a cycle sequence in such a way that at t = 450 s each cycle has run, within which two thin slabs are produced and rolled into the end product. As can be seen from the diagram, a pair of slabs (1a, 1b) or (2a, 2b) is poured between t = 0 and t = 440 s and 45 m from a heating zone (3a, 3b) into the system buffer (4a, 4b) advanced. Between t = 180 s and t = 220 s, the thin slab (1b) is moved by ferry (6b) from the casting line (xx) into the rolling line (yy) and then between t = 220 s and t = 290 s, ie in 70 s, transported 52.5 m from a ferry (6a, 6b) either driving backwards into the storage furnace (5) or moving forward into the holding furnace (7). It holds (1b) up to t = 330 s, ie for 40 s, and then transports it between t = 330 s and t = 370 s for a further 30 m until it enters the finishing train (8). The cycle is then repeated at t = 450 s = t-zero, after the thin slabs (3a, 3b) and (2a, instead of (2a, 2b) or (1a, 1b) after a cycle of 450 s 2b) have advanced by approx. 44 m corresponding to the casting speed of approx. 0.1 m / s.

It can be seen from the diagram in FIG. 3 that the working method of the system according to the invention has a rapid sequence, with an intermediate time of 136 s or 2 x 86 s remaining between every two rolling cycles of purely mathematically 304 s. The resulting idle times allow the drive units of the finishing mill stands to be operated in a high-performance stage during each 152 s rolling process without the electric motors being thermally overloaded. On the other hand, the diagram shows that the connection of a third casting line would no longer fit into the functional sequence. By accommodating sufficient storage capacity within the system, the furnace system designed according to the invention can provide sufficient bridging time with a shortened layout in order to ensure continuous production of the casting machines at least until the end of one or two casting batches in the event of downtimes of the roller train resulting from roller changes or other reasons guarantee.

Claims (6)

1. Method of manufacturing hot-rolled strips or sections from endless, continuously cast starting material in successive working steps of a finishing train (8), wherein the starting material endlessly and continuously cast in one or more casting machines (1a, 1b) is divided up into length pieces after hardening and these in the course of passage through a compensating oven (3a, 4a; 3b, 4b) are initially heated in a heating zone (3a, 3b) to rolling temperature, then conveyed into a buffer zone (4a, 4b) and thereafter into a storage zone and from this into the finishing train (8) and finish-rolled therein, characterised thereby that after removal from the buffer zone (4a, 4b) length pieces are brought into a ferry (6a, 6b) and ferried by this in transverse transport from the casting line (x-x) into the rolling line (y-y), stored therein in longitudinal transport oppositely to the conveying direction of the continuously cast starting material with use of a storage oven (5) arranged in the rolling line (y-y) near the compensating oven (3a, 4a; 3b 4b), and after recall from the storage oven (5) introduced by way of a ferry (6a, 6b), and from case to case by way of a holding oven (7) arranged downstream thereof and upstream of the rolling train (8), into the rolling train (8) and finish-rolled therein to the end product.
2. Method of manufacturing hot-rolled strips or sections from endless, continuously cast starting material in successive working steps of a finishing train (8), wherein the starting material endlessly and continuously cast in one or more casting machines (1a, 1b) is divided up into length pieces after hardening and these in the course of passage through a compensating oven (3a, 4a; 3b, 4b) are initially heated in a heating zone (3a, 3b) to rolling temperature, then conveyed into a buffer zone (4a, 4b) and thereafter into a storage zone and from this into the finishing train (8) and finish-rolled therein, characterised thereby that after removal from the buffer zone (4a, 4b) a length piece is initially transported within the casting line (x-x) in longitudinal transport by way of a ferry (6a, 6b) into a storage oven (20a, 20b) and after recall from the storage oven (20a, 20b) transported back into the ferry (6a, 6b) and brought by this in transverse transport from the casting line (x-x) into the rolling line (y-y) and introduced in forward longitudinal transport by way of the holding oven (7) into the rolling train (8) for finish rolling.
3. Method according to claim 2, wherein a length piece after removal from the buffer zone (4a, 4b) is initially transported within the casting line (x-x) in longitudinal transport by way of a ferry (6a, 6b) into a storage oven (20a, 20b) and after recall from the storage oven (20a, 20b) is transported back again into the ferry (6a, 6b) and ferried by this in transverse transport from the casting line (x-x) into the rolling line (y-y), characterised thereby that the length piece therein is firstly stored in rearward longitudinal transport into a storage oven (5) and after recall therefrom is introduced in forward longitudinal transport by way of the ferry (6a, 6b) and the holding oven (7) into the rolling train (8) for finish rolling.
4. Plant for the manufacture of hot-rolled strips or sections from endless, continuously cast starting material in successive working steps of a finishing train (8), for the performance of the method according to one or more of the preceding claims, comprising two CSP casting machines (1a, 1b) or casting lines (x-x) each with a respective compensating oven (3a, 4a; 3b, 4b) and a ferry (6a, 6b), as well as a CSP rolling train (8) comprising a holding oven (7) and laterally offset relative to the casting line (x-x), wherein each compensating oven (3a, 4a; 3b, 4b) comprises a heating zone (3a, 3b), a buffer zone (4a, 4b) as well as an oven part (5), which is constructed as a store, for bridging over standstill times of the rolling train (8) during continuous production of endless, continuously cast material, characterised thereby that an oven part (5) constructed as a store is arranged within the rolling line (y-y) at a lateral spacing near the compensating oven (3a, 3b; 4a, 4b) of the casting line (x-x), and an additional storage oven part (20a or 20b), which is separated from the compensating oven (3, 4) by a longitudinal spacing corresponding to the ferry (6a or 6b), is arranged in at least one, preferably in both, of the casting lines (x-x).
5. Plant according to claim 4, characterised thereby that the storage oven part (5) extends approximately parallelly along the heating and buffer zones (3a, 3b or 4a, 4b) of the compensating oven.
6. Plant according to claim 4, characterised thereby that the additional storage oven parts (20a or 20b) within the casting line (x-x) extend approximately parallelly along the holding oven (7) disposed in the rolling line (y-y).

Images