EP0361058A1 - Furnace plant to heat and reheat strip - Google Patents

Abstract

The subject matter is a furnace plant reacting to faults in the further processing and intended for heating and reheating strip (20), e.g. feed strip and thin slabs, having a heating furnace (14) and at least one storage furnace (15) for the strip (20), the heating furnace (14) of which contains a rolling and lifting-hearth system (16, 17, 19) having conveying rollers (16, 17) which are mounted on one side or on both sides outside the furnace space (18) and can be extended and retracted through the furnace side walls in intermediate spaces of the lifting hearths (19), the conveying rollers being apportioned to two roller tables (16 and 17) arranged one above the other, the top roller table (16) of which can be driven only in the entry direction and receives the entering strip (20), whereas the bottom roller table (17) can be driven so as to be reversible in rotation, in the plane of which roller table (17) the storage furnace (15) as well as devices (15, 21) for storing the pieces (20) of strip wound up, for example, into coils (22) are arranged on one front end of a heating furnace (14), and the feeder mechanisms for the further processing of the strip (20) are arranged on the other front end of the heating furnace (14), and in the event of a fault in the further processing, the strip (20) is conveyed by the bottom roller table (17) in the opposite direction for intermediate storage until the fault is removed. <IMAGE>

Description

The invention relates to a furnace system according to the generic term according to claim 1.

A continuous caster usually forms and cuts the continuous casting into thin slabs or pre-strips, which are then brought to a specified inlet temperature (e.g. 1,100 ° C) for the rolling process or another processing process in a heating furnace system and fed to the corresponding plant .

For economic reasons, in the event of malfunctions on and in the further processing plant, for example the rolling mill, the continuous casting installation must continue to work, so that, in the worst case, at least the ladle content already in the casting process can still be poured. This results in the need to temporarily store the continuous casting sections, such as thin slabs and pre-strips.

It is known to avoid a direct dependence on the casting process and the rolling speed by temporarily storing the continuously cast starting material in the form of coils or in elongated length in storage furnaces from which the rolling mill is supplied (cf. EP-A-0 264 459). With these storage furnaces, however, the above-described malfunctions in the rolling mill cannot generally be compensated for, since the amount of the primary material to be stored exceeds at least one long interruption the largest possible absorption capacity of the storage furnaces, so that the continuous casting must be interrupted in its outlet.

The invention has for its object to provide an economically and rationally operating furnace system with which interruptions on and in the rolling mill or in further processing can be compensated for with the least possible effort and energy and time loss at least until the casting ladle which is already in the casting process is completely emptied .

This object is achieved by the characterizing part of claim 1.

This enables the pre-strips or thin slabs separated from the continuous casting to be selectively fed from the heating furnace for further processing or, in the event of a malfunction in the further processing plant, from which the heating material can be re-processed directly after it has been eliminated Heating oven is recorded and heated to the inlet temperature for further processing for a relatively short time.

For this purpose, it is expedient if the furnace system is designed in accordance with claim 2, as a result of which in particular the space required for the storage furnace or furnaces can be kept relatively low.

For primary material that cannot be wound into coils, the furnace system is advantageously equipped according to claim 3. This system also guarantees a direct conveying path from the storage furnace through the heating furnace for further processing without any special effort.

The proposal according to claim 4 serves to ensure that, in the event of a malfunction in the rolling process, the continuous casting process never has to be interrupted until the pouring ladle which is already in operation is emptied.

With claims 5 and 6, particularly advantageous modes of operation of the furnace systems are proposed.

• Figur 1 in schematischer Seitenansicht eine Ofenanlage mit einem Rollenhubherd-Wärmofen und auf dessen wärmgut-Einlaufseite angeordneten Schneide- und Speichervorrichtungen;
• Figur 2 eine Draufsicht auf die Ofenanlage nach Figur 1; und
• Figur 3 einen Querschnitt durch den Wärmofen der Figur 1, in größerem Maßstab.

The subject matter of the invention is described below using an exemplary embodiment and illustrated in the accompanying drawing. This shows in

• FIG. 1 shows a schematic side view of an oven system with a roller-type hearth-type heating oven and cutting and storage devices arranged on its warm material inlet side;
• Figure 2 is a plan view of the furnace system of Figure 1; and
• 3 shows a cross section through the heating furnace of Figure 1, on a larger scale.

1 and 2 show an oven system which is connected behind a continuous casting mold 10 of a continuous casting machine, not shown, and its take-off rollers 11 with a horizontal roller table 12 and a flying cutting device 13. The furnace system contains a roller-hearth heating furnace 14 and two storage furnaces 15.

The roller hearth system of the heating furnace 14 contains two stacked roller tables 16 and 17, the conveyor rollers of which, as can be seen from FIG. 3, are mounted on both sides outside the furnace chamber 18 and, guided and moved laterally by their drive devices, through openings in the two furnace side walls into the furnace chamber 18 retractable and retractable from it. In the case of a lifting hearth 19 located below these conveying rollers, the upper roller table 16 can only be driven in the inlet direction in order to transport the section separated from the continuous casting as a heating item 20 (preliminary strip, thin slab) into the heating furnace 14. In contrast, the conveyor rollers of the lower roller table 17 arranged below are reversible, that is to say they can be driven both in the same direction of rotation as the upper roller table 16 and in the opposite direction of rotation. The conveyor rollers of both roller tables 16 and 17 are arranged exactly above one another with sufficient gaps. Within these gaps, the lifting hearth benches 19 can be moved vertically in the direction of the double arrow in a suitable number. This vertical movement of the lifting hearth benches 19 extends from its lowest position below the working level of the lower roller table 17 to over the working level of the upper roller table 16 such that the conveyor rollers to be introduced from the outside into the furnace chamber 18 of one or the other roller table 16 or 17 are each below the overlying heat 20 can be moved into and out of the spaces between the lifting hearth benches 19.

On the heating material inlet side of the heating furnace 14, a coil winding device 21 is arranged in the working plane of the lower roller table 17, which is designed both for winding the strip-shaped heating material pieces 20 into easily storable coils 22 and for unwinding them after their storage time, around the heating material pieces 20 to be able to insert it again as a stretched opening strip into the heating and rolling process via the lower roller table 17. In addition to the coil winding device 21, a storage furnace 15 in the manner of a bell-type furnace with a plurality of chambers accommodating the coils 22 is arranged on rails 23 on both sides.

The operation of the furnace system according to Figures 1 to 3 is as follows:

Via the roller table 12, the continuous casting 20 runs through the flying cutting device 13 into the heating furnace 14 onto the upper roller table 16 and is cut to a specific pre-measure, after which it runs completely into the heating furnace 14 by driving the upper roller table 16. As soon as it is in full length in the furnace chamber 18 on the upper roller table 16, its conveying circulation is stopped. The lifting hearth 19 moves vertically into the uppermost position and lifts the preliminary strip 20 from the upper roller table 16. Its conveyor rollers 16 now move laterally out of the furnace chamber 18, so that the sliver 20 can be lowered freely down to above the working level of the lower roller table 17.

The preliminary strip 20 is brought to the required drawing or rolling temperature in this position. Here, all the conveyor rollers of the upper roller table 16 are retracted into the furnace chamber 18 in time to accommodate the new preliminary strip 20.

The lower roller table 17 now also moves from the outside with its conveyor rollers into the furnace chamber 18 between the lifting hearth benches 19. The lifting hearth 19 then moves slowly down and gently places the preliminary strip 20 on the lower roller table 17. This then runs forward with undisturbed rolling operation and conveys the correctly reheated pre-strip 20 to the first stand of the rolling mill. As soon as the roller table 17 is free, its conveyor rollers are moved out of the furnace space 18 into the open again until the subsequent sliver 20 has the desired temperature.

In the event of a malfunction in the rolling mill, the last-mentioned conveying movement of the lower roller table 17 is not carried out in the direction toward the rolling mill, but by a reversing circuit to the rear to the coil winder 21, which produces a coil 22 from the preliminary strip 20. One of the movable hood furnaces 15 travels with an empty chamber at the level of the coil winder 21 for its absorption and heat storage. These processes are repeated until the malfunction in the rolling mill has been rectified or until the ladle in operation has been emptied.

After that, when the malfunction in the rolling mill has been remedied, the coils 22 are initially unwound again to stretched pre-strips 20 and positioned again in the heating furnace 14 via the lower roller table 17 for mostly brief reheating on the lifting hearth benches 19. When the required further processing temperature is reached, the pre-strips 20 can be fed to the further processing in a relatively rapid sequence. Continuous casting is continued in good time during the last heating processes, so that there is practically no interruption.

In the position of a strip-shaped primary material that is not so well suited for winding into coils, it is of course also possible to use the known storage ovens with ceramic solid stoves, which accommodate the entire length of the stretched sliver or thin slab. However, these storage furnaces require considerably more space and a more extensive conveyor system with a roller table that can transport the hot items longitudinally out of the heating furnace and integrated tractors that extend into the storage furnaces.

Fixed hearth storage furnaces of this type are immobile and can therefore be made heatable in a relatively simple manner, for example with the exhaust gases from the heating furnace, in order to keep the stored heat 20 well warm. With adequate fiber insulation of the storage heaters, only a weak heating is required. For the transport of heating material, each oven hearth advantageously has a maximum of only four cross tractor slots, in such a way that both the storage and the emptying of the storage furnaces are carried out by the same cross tractor.

If you only disregard the different storage of the stretched pieces of hot material, the sequence before and in the heating furnace 14 is the same as that described above for FIGS. 1 to 3. In this respect, the working methods are similar, with the exception of the conveying process for the temporary storage of the hot items.

Reference symbol list:

• 10 continuous casting mold
• 11 guide rollers
• 12 continuous casting roller table
• 13 flying cutter
• 14 heating furnace
• 15 storage furnace (hood furnace)
• 16 upper roller table
• 17 lower roller table
• 18 furnace chamber (heating furnace)
• 19 lifting hearth benches
• 20 heating material (preliminary strip, thin slab)
• 21 Coil winding device
• 22 coils
• 23 tracks

Claims (6)

1. Furnace system for heating or reheating band-shaped heating material (20), for example pre-strips and thin slabs, with a heating furnace (14) and at least one storage furnace (15) for the heating material (20), the heating furnace (14) being a roller and Lifting hearth system (16, 17, 19) with transport rollers (16, 17), which are mounted outside the furnace chamber (18) and can be moved in and out through the openings in the furnace side walls in the spaces between the lifting cookers (19), and with lifting cookers (19), which can be lifted between the transport rollers (16, 17) from their position below their working level to above their working level,
characterized,
that the transport rollers are divided into two roller tables (16 and 17) arranged one above the other, the upper roller table (16) of which can be driven in the infeed direction and receives the incoming heating material (20), while the lower roller table (17) can be reversibly driven in its plane on one end of the heating furnace (14) the storage furnace (15) and devices (15, 21) for storing the items to be heated (20) and on the other end of the heating furnace (14) the feeder devices for the further processing of the heating material (20) are arranged . 2. furnace system according to claim 1,
characterized,
that the devices for storing contain at least one coil winding device (21) with which the heating material (20) can be wound into coils (22) and unwound back into stretched heating material pieces (20), and that this coil winding device (21) has at least one Storage furnace (15) is assigned, which can be moved into a required takeover or delivery position for the respective coil. 3. Furnace system according to claim 1,
characterized,
that the devices for storing contain at least one storage oven which holds the stretched hot material pieces (20) and which is connected to the lower roller table (17) of the heating furnace (14) via a conveying passage which moves the hot material pieces (20) longitudinally and transversely. 4. Furnace system according to one of claims 1 to 3,
characterized,
that the storage capacity of the storage furnaces (15) corresponds at least to the content of the ladle converted into the hot items (20). 5. Operation of the furnace system according to claims 1 and 2,
characterized,
that the piece of heat (20) is conveyed onto the conveyor rollers of the upper roller table (16) which have been moved into the furnace chamber (18) and is then taken over by the raised lifting cookers (19) which, after the upper conveyor rollers (16) have been extended, the piece of heat (20) lower, which is then heated up to the required temperature, after which it is placed on the conveyor rollers of the lower roller table (17) which have been moved into the furnace chamber (18) and which, depending on the demand, the heat item (20) either to the front through the furnace exit for further processing or in the event of their malfunction opposite to the coil winder (21) transported for winding up and storing in the storage furnace (15), and that after the fault has been rectified, the coil (22) is unwound via the coil winder (21) and again in stretched length Introduced into the heating furnace (14) via the lower roller table (17), rewarmed to the processing temperature lying on the elevating bench (19) and then the output side of the processing unit work is supplied. 6. Operation according to claims 1 and 3,
characterized,
that the hot item (20) is conveyed onto the conveyor rollers of the upper roller table (16) which are retracted into the furnace chamber and is then taken over by the raised lifting cookers (19) which, after the upper conveyor rollers (16) have been extended, lower the item (20), which thereupon up to the required temperature is heated, after which it is placed on the conveyor rollers of the lower roller table (17) which are retracted into the furnace chamber (18) and which, depending on the demand, the heat item (20) either towards the front through the furnace exit for further processing or in the event of its malfunction in its opposite direction stretched length transported to the level of the storage furnace, where a transverse conveyor device starting from the storage furnace is integrated into the roller table, which pulls the hot item (20) transversely to the longitudinal direction into the storage oven and stores it on the stove benches, after which the hot item (20) is processed by the same cross conveyor and the lower roller table (17) back on the lifting hearth (19) for reheating and then the output side is fed to the further processing process.

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