EP3110981A1

EP3110981A1 - Method and system for thermally treating elongate, flat metallic material, in particular aluminum rolled ingots, in a ring hearth furnace

Info

Publication number: EP3110981A1
Application number: EP15711059.4A
Authority: EP
Inventors: Joachim Nacken; Krzysztof Hornig
Original assignee: SMS Group GmbH
Current assignee: SMS Group GmbH
Priority date: 2014-02-26
Filing date: 2015-02-26
Publication date: 2017-01-04
Anticipated expiration: 2035-02-26
Also published as: CN106170568A; WO2015128416A1; DE102015203376A1; CN106170568B; EP3110981B1

Abstract

The invention relates to a method and to a system for thermally treating elongate, flat metallic material, in particular aluminum rolled ingots (2), in a furnace, a ring hearth furnace (1) being used as the furnace, said ring hearth furnace having a rotary-driven ring hearth floor (7a) between a thermally insulated outer housing (3) and a thermally insulated inner housing (4), said ring hearth floor being sealed off from the housing (3, 4), and at least one closable charging and discharging opening (15; 15a, 15b). For convection-heating of the aluminum rolled ingots (2) introduced into the ring hearth furnace (1), air, which is sucked upwards by circulation fans (19), which are provided on the ceiling side and distributed over the circumference of the ceiling (6), out of the ring hearth interior (1a), which is enclosed by the outer and inner housing (3, 4), is first conducted along heating means (20a, 20b; 21), which are arranged on the ceiling side and project into the hearth interior (12) and then flows into pressure ducts (22), which extend on the inner walls of the outer and inner housing (3, 4) and from which the air, which is increasingly heated up during the heat-up phase, is blown at the aluminum rolled ingots (2) via slot nozzles (23) in order to heat the aluminum rolled ingots (2).

Description

Method and plant for the thermal treatment of elongated, flat metallic material, in particular aluminum ingots, in a ring hearth furnace

The invention relates to a method for the thermal treatment of

elongated, flat metallic material, in particular aluminum ingots, in an oven used for temperature control and monitoring as well

Furnace control is connected to a higher-level process control system, using as a furnace, a ring hearth furnace is used between a

heat-insulated outer casing and a heat-insulated inner casing has a sealed against the housing, rotary ring hearth bottom, said sealed with a heat-insulated ceiling ring hearth furnace is formed with at least one closable loading and discharge opening and is heated with gas or electric. Furthermore, the invention relates to a system comprising a ring hearth furnace for carrying out the method.

In a ring hearth furnace is a special form of a

Rotary hearth furnace, both types of furnace in the industry for a long time prior art and in the special form as a ring hearth in the steel industry, there especially in the forging industry for heating forging blocks, but also in the heat treatment, especially for carburizing example of

Gear parts, are used. A rotary hearth furnace in ring type to

Heat treatment of such workpieces has become known from DE 8422370.7 U1.

As known from DE 10 2009 053 343 A1, there is a heating or

Homogenization of aluminum ingots to this day almost always in pusher ovens, which are operated with convection heating and in which the goods in the

Run through the furnace housing while heated to the rolling temperature of 500 - 560 ° C. The pusher furnace comprises the heat-insulating bricked housing with a seen in the direction of passage of the goods front end wall and a rear end wall, two connecting the two end walls together

Longitudinal walls and a transport device for conveying the zu

treated good through the oven housing. The transport device is designed such that it receives the elongated, flat Good transversely to the direction of passage. For this purpose, the material to be treated is placed on sliding shoes, which can be moved to arranged in the furnace chamber rails, usually by means of a hydraulic impact device.

The existing for loading and unloading of the goods on the front sides of the furnace doors have an opening cross-section, which must correspond to at least the dimensions of the treated, elongated flat metallic Guts. That suggests for aluminum ingots, whose length is one

Is several times the thickness and which typically has a thickness of up to 0.8 m, a width of up to 2.6 m and a length of up to 8.4 m, which makes the loading and unloading

Discharge opening or openings for loading and unloading must release an extremely large passage, even if the aluminum ingots are pushed standing on its narrow, long end face through the oven.

Due to the strong circulation of the blown air in the oven, which also takes place immediately in front of the large-area frontal doors, with forced open doors, part of the blowing air, which is heated up to 650 ° C, is forced out of the oven. At the same time, cold outside air flows into the furnace chamber, which then has to be brought to the treatment temperature. In addition, the hot aluminum ingots standing in front of the doors during loading and unloading emit a large amount of heat to the outside, which further worsens the energy balance. For heating or homogenization of aluminum ingots, further low-temperature furnaces (cf. DE 2758292 C) are known, which are operated by means of convection heating. Such a deep furnace has a limited by insulated outer walls, rectangular furnace chamber, the top of a Abheb- or

attachable or horizontally movable stable oven lid is closed.

The lot sizes, which are equipped with low-temperature ovens, is usually between 30 t and 300 t, wherein the aluminum ingots standing upright on one of their narrow end faces in corresponding receptacles at the bottom of the furnace or flat lying on each other, separated by spacers, in the Tiefofen be charged.

When the convection heating of the deep furnace is a blowing of the

Aluminum ingot with high air speed. In the case of the aluminum ingots, which are stationary from the time of loading to the time of removal, uneven heating or partially excessive heating, so-called hot spots, can occur. The aluminum rolling ingots are loaded and unloaded with the help of a block tongs movable over the deep furnace or a hall crane. If a heated aluminum ingot removed from the deep furnace, which is at least over a partial length and over the entire width of the furnace chamber extending furnace cover lifted or driven up, with a large part of the hot Bleglasungsluft exiting the furnace, which inevitably leads to a reduction of the preset oven temperature leads.

The invention has for its object to provide a method and a system for the thermal treatment of aluminum ingots, with which the advantages of a proven in the steel industry ring hearth furnace with the proven in the aluminum industry with a simplified structure Combine convection heating to a significantly reduced

Energy consumption and variable modes of operation.

This object is achieved by a method according to the invention that for convection heating introduced into the ring hearth furnace aluminum ingots provided on the ceiling, distributed over the circumference of the ceiling circulation fans from the chambered inside of the outer and inner casing Ringherdinneren upwardly sucked air along along arranged on the ceiling side, projecting into the hearth interior heating means is passed and then flows into itself on the inner walls of the outer and inner housing extending pressure channels from which the aluminum ingots with the during the heating phase increasingly warming air for heating the aluminum ingots via slot dies be blown. The ceiling side numerous circulating fans and heating means, eg. B. directly heated by gas with hot air or gas burners or electrically heated over

Elektrostrahlheizrohre, in conjunction with the pressure on the inner walls of the housing from top to bottom extending pressure channels in the hearth furnace furnace heating of aluminum ingots with intensive

Convection of the closed loop from the inside of the furnace sucked upwards and from there after the heating by the heating means along the inner walls down to the bottom with blowing of the aluminum ingots recycled air. The blowing air exits at a rate of about 40 m / s to 60 m / s from the slot nozzles distributed in the pressure channels to below the heating means over the entire height of the furnace interior. Thus, a highly efficient heat transfer with fast heating rate and high throughput can also be achieved for heating or heating of aluminum ingots. The rotation of the ring hearth floor with the aluminum ingots standing thereon ensures a very good temperature uniformity in the annealed material. According to a proposal of the invention, the aluminum ingots are turned off in an upright position on the ring hearth bottom so that their narrow

Long sides with the recirculated air directly blown and their wide

Rolling surfaces are flowed around by the air. This results in an all-round flow around the aluminum ingots, which can still be favored by the fact that the aluminum ingots are placed on a resting on the ring hearth bottom, continuous storage rack in honeycomb form of heat-resistant cast steel. The ring hearth furnace can be inventively for

Heating the aluminum ingots to rolling temperature and in contrast increased temperature also operate to homogenize the aluminum ingots, the aluminum ingots after expiration of the

Homogenization time by blowing cold air into the interior of the ring hearth cooled superficially and at the end of a certain cooling time through the

Residual heat of the aluminum ingots are heated again to rolling temperature. The to homogenize the aluminum ingots with a

Residence time in the oven of z. B. 20 to 25 hours required temperature of the aluminum ingots of about 600 to

650 ° C is via thermocouples and reference junction directly in the

Programmable Logic Controller (PLC), in which also the

Temperature control takes place. For monitoring and control of the ring hearth furnace is formed with independent control zones and zone-independent control loops. The setpoints and parameters required for an annealing program are loaded from the existing higher-level process control system into the corresponding furnace control.

The ring hearth furnace advantageously allows operation with

batchwise or continuous loading. Depending on the oven diameter and thus the dimensions of the usable, heated Furnace space aluminum ingots with a total weight of, for example, 430 1, 530 1 or 620 t are introduced at maximum load.

According to the invention, it is provided that in the batch operation of the empty ring hearth furnace or its use space is filled to the beginning of an annealing and completely empty after reaching the rolling temperature of all aluminum ingots. When the optional Konti operation is a warmed up

Removed aluminum ingot and then further rotated the ring hearth floor by one bar before a cold aluminum ingot is introduced to warm up. It is thus created an empty space shortly before the removal of the heated to rolling temperature bar and the newly charged, cold ingot to avoid a negative temperature influence. For the same reason, the loading and unloading opening is closed after each removal or loading.

The heating process starts after the glow plug to be used has been called from the PLC. The air temperature is set to an excess temperature (max 650 ° C) and automatically maintained at this excess temperature. During the time in which is driven with overtemperature, the

Ring hearth bottom advantageously continuously rotated slowly to avoid overheating on the narrow longitudinal sides of the aluminum ingots and to even out the temperature, which also contributes significantly to the rotation of the ring hearth bottom. The ring hearth furnace allows for always constant loading and unloading a load with the aluminum ingots from above, z. B. by means of a hall crane, or from the side, z. B. by means of a handling robot.

Regardless of whether loading from the top or from the side, different loading strategies can be carried out, namely by distributing the aluminum ingots circumferentially with their wide rolling surfaces spaced one-lane or two-lane with then also spaced apart narrow longitudinal sides, ie on an outer circular path and a concentric inner circular path, can be placed in the hearth interior, the two-lane loading can be done with in-line or offset aluminum ingots. The two-lane loading with offset aluminum ingots and no fixed positions in relation to the ring hearth furnace allows a maximum batch weight, z. B. 620 t, compared to a two-lane loading of series shut down aluminum ingots with a batch weight of about 440 t, the same

Dimensions and weights of the individual aluminum ingots provided.

A further measure according to the invention provides that the actual temperature of the aluminum rolling bars per zone, which is predetermined by each of the ceiling-side circulation fans, is periodically checked, for which purpose the rotational movement of the ring hearth bottom is briefly stopped. The measured values are processed in the PLC or the higher-level process control system and loaded into the furnace control.

In a plant for carrying out the method is according to the invention

provided that the ring hearth furnace on the rotationally driven

Ring hearth floor aligned annular surface of his ceiling distributed on the one hand circulating fans and on the other hand both the inner wall of the outer housing and the inner wall of the inner housing associated heating means, the circulation fans and the heating means are passed through the ceiling into the upper Ringherdinninnere, and with slot nozzles having formed pressure channels, which extends below the heating means to the

Inner walls of the outer and inner housing extend. The to

Convection heating of a ring hearth furnace requires aggregates are thus easily accessible for the maintenance personnel, with an easy removal and installation of the circulation fans and the heating means using the hall crane is possible. It is proposed that gas burners are provided for the ring hearth furnace formed with exhaust pipes and cooling air supply lines as heating means, which are spaced apart from each other by an outer housing burner ring and a

Inner housing burner ring are arranged forming, with their burner tubes adjacent to the inner walls of the outer and the inner housing extending immersed in the upper Ringherdinninnere. The aluminum rolling ingots parked in the upright position with their short end faces on the ring hearth bottom are thus blown from their two narrow longitudinal sides with the air which accelerates out of the slot nozzles. The over the circulating fans sucked in from the bottom upwards air is passed after its heating by the two burner rings on the inner walls of the outer and inner housing in the local pressure channels.

An advantageous embodiment of the invention provides that the

rotatably mounted ring hearth bottom is mounted on fixed rollers and has a toothed ring for driving, with which a pinion acted upon by a frequency-controlled electric motor meshes. It is thus only a working according to the operating principle drive block drive unit needed to stop the rotational movement or the positionally accurate clocking of the driven

Ensured ring hearth soil. The rollers on which the ring hearth bottom expires offer a long service life due to central lubrication of their rolling bearings.

Another embodiment of the invention provides that in each of a circulating fan predetermined fan zone at least one with his

Measuring lance is provided by the inner or outer housing in the ring hearth inside immersing Andrück thermocouple. The pressing thermocouples can be actuated electromechanically and serve on the one hand to measure the air temperature and on the other hand to measure the temperature of the aluminum ingots. According to one embodiment of the invention, the at least one loading and unloading opening of the annular hearth furnace for loading and unloading from above or from the side with a horizontal in the ceiling or on the outer circumference of the

Outer housing laterally movable oven door formed. Regardless of whether a loading and unloading opening or whether two such openings are present, in which case one opening for loading and the other is used for unloading, a flexible loading is guaranteed at always constant loading and unloading and energy efficient always only one small section of the annular hearth furnace open at the top of the ceiling or on the side of the outer housing.

It is recommended that in case of two by one oven door

closable loading and unloading openings for thermal separation of the discharge opening for hot aluminum ingots and the loading opening for cold aluminum ingots between the two openings a separation weir is provided.

Further features and details of the invention will become apparent from the

Claims and the following description of simplified illustrated in the drawings embodiments of the invention.

Show it:

Figure 1 in a longitudinal section of a plant for the thermal treatment of aluminum ingots with a means for

Convection heating of aluminum rolling ingot trained annular hearth furnace;

Figure 2 shows the annular hearth furnace of Figure 1 in plan view; Figure 3 is a plan view of a ring hearth furnace as before in Figure 1, in contrast, has an opening for loading and a separate opening for discharging the aluminum ingots; Figure 4 is a schematic plan view of the ceiling side a loading and

Discharge opening having annular hearth furnace, the one-lane loading of the ring hearth with the aluminum ingots;

Figure 5 is a plan view as before in Figure 4, in contrast, with two-lane

Loading symmetrically in series aluminum

Rolling ingots; and

Figure 6 is a plan view as before in Figure 5, in contrast with not

symmetrical in series, but offset from train to train

parked aluminum rolling ingots.

From an industrial plant for the thermal treatment of elongated, flat metallic Good a ring hearth furnace 1 for heating or heating and / or homogenization of aluminum ingots 2 is shown in the drawing figures. The annular hearth furnace 1 consists of an outer housing 3 and an inner housing 4, the inside complete with a heat insulation 3a, 4a, z. As ceramic and mineral mats are provided. The furnace chamber or the hearth interior 1 a closing furnace roof 6 is also with a

Thermal insulation 6a lined. The bottom of the room between the

Outer housing 3 and the inner housing 4 bridging furnace bottom 7, which has a thermal insulation 8, for example, lightweight concrete, has in its space corresponding to the use of a space

Rotary ring hearth bottom 7a, which is sealed here opposite the furnace housing or the furnace bottom 7 on both sides, ie the separation points, via a circumferential water cup 9. The rotary-driven ring hearth bottom 7 a is mounted on fixed rollers 10 and is of a frequency-controlled electric motor 1 1 driven, which meshes via a pinion 12 with a ring gear 13 of the ring hearth bottom 7a. On the outer circumference of the

Furnace housings are for the introduction of cooling air and removal of exhaust gases

Lines 14 provided.

The loading and unloading of the ring hearth furnace 1 is carried out in the embodiments from above by means of the hall crane, to which the loading and unloading opening 15 can be temporarily temporarily opened and closed by a horizontally movable in the ceiling 6 by an electric motor with rack drive oven door 16. The aluminum ingots are in the from Figure 1 to

Removing edgewise position with its narrow end faces on one

honeycomb storage shelf 17 of the ring hearth bottom 7a parked. As shown in Figure 3, two openings 15a, 15b can be provided adjacent to each other in the furnace roof instead of the one loading and unloading opening 15, which can alternately be closed or opened alternately by a horizontally displaceable oven door 16, wherein the opening 15a of Charge with cold aluminum ingots and the opening 15b is used for unloading or removal of the heated aluminum ingots. A divider 18 provides thermal separation of the "hot" unloading station from the "cold" loading station.

For heating or heating and / or homogenization of the aluminum ingots 2, the annular hearth furnace 1, to which a higher-level process control system or a higher-level computer is assigned for regulation and control, not shown, formed with means for convection heating. As can be seen from FIGS. 2 and 3, with the exception of the area of the loading and unloading opening 15 or the openings 15a, 15b for loading and removal on the oven roof 6, they are in alignment with the rotary drive

Ring hearth bottom 7a lying circumferentially distributed numerous circulation fans 19 arranged, the ends with their vanes 19a in the hearth interior 1 a with some air above the upright aluminum ingots 2 ends. Still protruding through the furnace roof 6 are numerous heating means 20a, 20b arranged in the form of gas burners arranged on an outer burner ring and an inner burner ring, which are provided with their

Burner tubes 21 on the one hand close to the outer housing 3 and its

Heat insulation 3a and close to the inner housing 4 and its heat insulation 4a and extend in the ring hearth inside 1 a at the level of the impellers 19a of the circulation fans 19 ends. With some distance below the burner tubes 21 are distributed to the heat insulation 3a of the outer housing 3 and the heat insulation 4a of the inner housing 4 over the entire circumference of the annular hearth inside 1 a - except again only the range of loading and

Discharge opening 15 and the openings 15a, 15b, which also for the

Heating means applies - up to the furnace bottom 7 out extending pressure channels 22 formed distributed over the height of numerous slot nozzles 32, the air outlets are aligned with the narrow longitudinal sides 24 of the switched on or off aluminum rolling ingots 2.

For convection heating during heating / heating or homogenization of the aluminum ingots 2 sucked by the circulation fans 19 from bottom to top from the annular hearth inside 1 a supported by baffles 25 deflected to the burner tubes 21, further heated and closed circuit over the lateral pressure channels 22 returned to the bottom. When passing through the pressure channels 22, the slats 23 cause the aluminum ingots to be narrowed from both sides

Long sides blown 24 and flow around in the sequence of their broad

Rolling surfaces 26. For measuring and monitoring the temperature of the

Blowing air used in the forward and return of the circulator built-in thermocouples, for measuring the temperature of the aluminum ingots 2 are in each of a circulating fan 19 with his

Impact range predetermined fan zone in the embodiment of Figure 1 from the outside through the inner housing 4 with its measuring lances 27 in the ring hearth inside 1 a dipping, electromechanically operated pressure-thermocouples 28 is provided. A heating process can thus be controlled and regulated. A heating process begins after the glow plug to be used has been called from the PLC. This can be done so that the air temperature is set to an overtemperature (max 650 ° C) and automatically to this

Overtemperature is maintained. During this time, in which is operated at excess temperature, the annular hearth bottom 7a is continuously rotated slowly to avoid overheating on the narrow longitudinal sides 24 of the aluminum ingots 2. The current temperature of the aluminum ingots is periodically checked via the pressing thermocouples 28 per fan zone, for which purpose the rotational movement of the annular hearth bottom 7a is briefly stopped. Shortly before reaching the corresponding material setpoint temperature, the temperature of the recirculation air is automatically reset to the rolling-block target temperature in order to avoid overheating. After all aluminum ingots are in the tolerance range, the material-dependent holding time starts. The end of the cycle is indicated acoustically or visually, whereupon the rolled aluminum bars 2 brought to a rolling temperature of about 520 ° C. can be removed and rolled individually with the existing hall crane.

The assignment of the ring hearth furnace 1 with aluminum ingots 2, for the various AL alloys come into question, the ingots, for example, 1350 mm wide, 600 mm thick and 4500 mm long, can be variable

Strategies are made. As shown in Figure 4, the aluminum ingots 2 on a circular path circumferentially distributed with their wide rolling surfaces 26 spaced from each other in the hearth interior 1 a have been turned off. According to Figure 5, the aluminum ingots are 2 - and insofar consistent with u.a. Figure 1 - has been placed on two circular paths in the hearth interior 1 a, the

Aluminum rolling ingots 2 of the outer circular path are at a distance in series with the narrow longitudinal sides 24 of the aluminum ingots 2 of the inner circular path. FIG. 6 shows a two-lane load, as previously in FIG. 5, but not with aluminum rolling bars 2 arranged radially in series, but rather the aluminum rolling bars 2 are of concentric inner Circular path offset to the aluminum ingots 2 of the outer circular path in the hearth interior 1 a turned off.

The thus flexible loading takes place with always constant loading and unloading

Discharge position, namely predetermined by the in the embodiments with at least one in the furnace roof 6 horizontally movable oven door 16th

trained loading and unloading opening 15, instead. The two-lane loading enables the highest possible throughput with correspondingly high batch weights. The for heating and homogenizing of

Aluminum rolling ingots with convection heating trained annular hearth furnace brings compared to the used in industry shock and Tieföfen numerous advantages with it, as achieved by the small loading and unloading, minimized heat loss, high thermal efficiency

Combustion air preheating, low NO _x values in the exhaust gas, a reduced energy loss due to low O 2 values in the exhaust gas and a total of one

lower specific energy consumption.

LIST OF REFERENCE NUMBERS

1 ring hearth furnace

1 a ring hearth interior

2 aluminum ingots

3 outer casing

3a thermal insulation

4 inner housing

4a heat insulation

6 ceiling / oven ceiling

6a heat insulation

7 oven floor

7a rotary driven ring hearth bottom

8 heat insulation

9 water cup

10 roll / roller

1 1 frequency-controlled electric motor

12 pinions

13 sprocket

14 line (supply of cooling air and / or removal of exhaust gas)

15 loading and unloading

15a loading opening

15b removal opening

16 oven door

17 storage rack

18 line of defense

19 circulation fan

9a impeller

20a / b heating medium (gas burner)

21 burner tubes

22 pressure channel slot

narrow longitudinal side baffle

wide rolling surface

measuring probe

Press-on thermocouple

Claims

claims:

1 . Process for the thermal treatment of elongated, flat

Metallic material, in particular aluminum ingots (2), in an oven, which is connected to a higher-level process control system for temperature control and monitoring and furnace control, wherein as a furnace

Annular hearth furnace (1) is used, which between a thermally insulated outer housing (3) and a thermally insulated inner housing (4) has a against the housing (3, 4) sealed, rotationally driven ring hearth bottom (7a), said with a thermally insulated ceiling (6) sealed

Ring hearth furnace (1) with at least one closable loading and

Discharge opening (15; 15a; 15b) is formed and is heated with gas or electrically,

characterized in that

for convection heating in the ring hearth furnace (1) introduced

Aluminum rolling ingots (2) provided on the ceiling side, over the circumference of the ceiling (6) distributed circulating fans (19) from the from the outer and inner housings (3, 4) chambered hearth interior (1 a) upwardly sucked air along along arranged on the ceiling side, in the

21) is passed and thereafter flows into the inner walls of the outer and the inner housing (3, 4) extending pressure channels (22) from which the aluminum ingots (2) with increasing during the heating phase

warming air to heat the aluminum ingots (2) over

Slot nozzles (23) are blown.

2. The method according to claim 1,

characterized in that

The aluminum ingots (2) are placed in a vertical position on the ring hearth bottom (7a) so that their narrow longitudinal sides (24) with the circulated Air is blown directly and their wide rolling surfaces (26) are flowed around by the air.

Method according to claim 1 or 2,

characterized in that

the annular hearth furnace (1) for heating the aluminum ingots (2) to rolling temperature and at the opposite temperature also for homogenizing the aluminum ingots (2) can be operated, wherein the aluminum ingots (2) after the homogenization time by blowing cooled by cold air in the hearth interior (1 a) and heated at the end of a certain cooling time by the residual heat of the aluminum ingots (2) back to rolling temperature.

Method according to one of claims 1 to 3,

characterized in that

the ring hearth furnace (1) is operated with batchwise or continuous loading.

Method according to claim 4,

characterized in that

in batch operation, the empty ring hearth furnace (1) is filled to the top of an annealing and completely emptied after reaching the rolling temperature of all aluminum ingots (2).

Method according to claim 4,

characterized in that

in Konti-operation, a heated aluminum ingot (2) removed and then the ring hearth bottom (7a) is further rotated by one bar before a cold aluminum ingot (2) is introduced to warm up.

7. The method according to one or more of claims 1 to 6,

characterized in that

the aluminum ingots (2) circumferentially distributed with their wide rolling surfaces (26) spaced from each other in one lane or two lanes with then spaced apart narrow longitudinal sides in the hearth interior (1 a) can be turned off,

wherein the two-lane loading can take place in series or from circular path to circular path offset aluminum ingots (2). 8. The method according to one or more of claims 1 to 7,

characterized in that

in the heating phase of the ring hearth furnace (1) with set and maintained elevated temperature of the ring hearth bottom (7a) is continuously rotated to avoid overheating on the narrow longitudinal sides (24) of the aluminum ingots (2) and to equalize the temperature.

9. The method according to one or more of claims 1 to 8,

characterized in that

the actual temperature of the aluminum ingots (2) per zone, which is given by each of the ceiling-side circulation fans (19) with their effective range, is checked periodically, to which the rotational movement of the annular hearth bottom (7a) is stopped briefly.

10. The method according to one or more of claims 1 to 9,

characterized in that

the ring hearth furnace (1) is loaded from above or from the side with the aluminum ingots (2).

1 1. Plant for the thermal treatment of elongated, flat

metallic material, in particular aluminum ingots (2), comprising a furnace suitable for temperature control and monitoring and furnace control a parent process control system is connected, wherein as furnace a ring hearth furnace (1) is used, which between a heat-insulated outer casing (3) and a thermally insulated inner casing (4) against the housing (3, 4) sealed, rotationally driven ring hearth bottom (7a) , wherein the closed with a thermally insulated cover (6)

Annular hearth furnace (1) has at least one closable loading and unloading opening (15; 15a, 15b) and is heated with gas or electrically, for

Performing the method according to one or more of claims 1 to 10,

characterized in that

the ring hearth furnace (1) via the annular surface of its ceiling (6) aligned with the rotary ring hearth bottom (7) distributes circulating fans (19) on the one hand and heating means (2) associated with both the inner wall of the outer housing (3) and the inner wall of the inner housing (4) on the other hand 21a), wherein the circulating fans (19) and the heating means (20a, 20b, 21) extend through the cover (6) to the upper annular hearth interior (1a)

are passed through, and formed with slot nozzles (23) having pressure channels (22) extending below the heating means (20a, 20b, 21) on the inner walls of the outer and the inner housing (3, 4).

12. Plant according to claim 1 1,

characterized in that

gas burners are provided spaced apart from each other forming an outer casing burner ring and an inner casing burner ring, their burner tubes (21) being adjacent to the inner walls of the outer and inner casings (3, 4). proceed in the upper ring hearth inside (1 a).

13. Plant according to claim 1 1 or 12,

characterized in that the rotationally driven ring hearth bottom (7a) is mounted on stationary rollers (10) and has a toothed rim (13) for driving, with which a pinion (12) acted upon by a frequency-controlled electric motor (11) meshes. 14. Plant according to one or more of claims 1 1 to 13,

characterized in that

in each of a circulating fan (19) predetermined fan zone at least one with its measuring lance (27) through the inner or outer housing (3, 4) in the ring hearth interior (1 a) immersed Andrück thermocouple (28) is provided.

15. Plant according to one or more of claims 1 1 to 14,

characterized in that

the at least one loading and unloading opening (15; 15a, 15b) of the

Ring hearth furnace (1) for loading and unloading from above or from the side with an in the ceiling (6) horizontally movable oven door (16) or on the periphery of the outer housing (3) laterally movable oven door is formed.

16. Plant according to claim 15,

characterized in that

at two closable by a respective oven door (16) loading and

Discharge openings (15a, 15b) for the thermal separation of

Discharge opening (15b) for hot aluminum ingots (2) and the

Loading opening (15a) for cold-aluminum ingots (2) between the two openings (15a, 15b) a separating weir (18) is provided.