EP2217394A1 - Method and device for producing a metal strip - Google Patents

Abstract

The invention relates to a method for producing a metal strip (1), particularly from steel. Liquid metal is fed from a dispensing vessel (2) to a solidification path (3) and the cast metal hardens along said solidification path (3). The aim of the invention is to obtain a damage-free strip with optimum quality, such that the liquid metal is provided on a first site (4) of the solidification path (3) that is embodied in the form of a conveying element that extends horizontally and that the cast metal leaves the conveying element (3) on a second site (5) that is at a distance in the direction of conveyance (F). Means (6, 7) are provided in direction of conveyance (F) on or behind the second site (5), said means maintaining the mass flow of the strip emerging from the solidification path (3) and/or the tension in the strip at a desired value. The invention also relates to a device for producing a metal strip.

Description

 Method and device for producing a strip of metal

The invention relates to a method for producing a strip of metal, in particular of steel, wherein liquid metal is supplied from a pouring opening of a solidification section and wherein the cast metal solidifies along the solidification section. Furthermore, the invention relates to an apparatus for producing a strip of metal.

With the method of horizontal strip casting, it is possible to cast melts of various steel grades close to the final dimensions in a range of less than 20 mm strip thickness. Systems of this type have already been described with which tapes can be produced. In particular, lightweight steels with a high proportion of C, Mn, Al and Si can be advantageously produced.

In the case of horizontal strip casting of steel, there is a direct connection of material in the liquid phase in the area of the melt application and the further processing steps of the solidified material over the cast strip. The cast strip is fed after solidification and leaving the casting machine on a transport path of further processing. The processing steps can be: straightening, rolling, cutting and unwinding (reeling, coiling).

This or similar components of an overall system can lead to tensile and mass flow fluctuations in the cast strip. Planting the disturbances in the direction of the liquid steel, it may lead to casting defects and negative effects of the cast strip, z. B. thickness variations, overflows, edge constrictions and band or flow rip. In particular, lightweight steels, which may have a very large solidification interval (ie, temperature window from the start of solidification from the melt to complete solidification and dependent zero strength or zero toughness temperatures), are additionally intolerant to tensile fluctuations also in the transport path.

The invention is therefore based on the object, a method of the type mentioned above and a corresponding device in such a way that it is possible to ensure even with disturbances of the type mentioned that the cast strip has a high quality.

The solution of this object by the invention according to the method is characterized in that liquid metal is deposited at a first location of the formed in the form of a horizontally extending conveyor element solidification line and that the solidified metal leaves the conveyor element at a nem spaced in the conveying direction second location, wherein Means are provided in the conveying direction at or behind the second location, with which the mass flow of the belt leaving the solidification section and / or the tension in the belt is maintained at a desired value.

Preferably, the means behind the second location maintain a predetermined tension in the belt. The means can maintain a temporally constant tension in the band, in particular behind the second location.

In the solidification stretch, a tensile stress of almost zero can be maintained in the strip.

The proposed device for producing a strip of metal, in particular of steel, comprises a pouring opening, with which liquid metal can be fed to a solidification section, wherein the cast metal is transported on the solidification section in a conveying direction on which it solidifies. The device is inventively characterized in that the Solidification distance is formed as a horizontally extending conveyor element, wherein the liquid metal can be abandoned at a first location of the solidification line, wherein the solidified metal can leave the conveyor element at a second spaced apart in the conveying direction and wherein in the conveying direction behind the second location means to maintain a desired mass flow of the belt leaving the solidification section and / or a desired tension in the belt.

The means for maintaining a desired mass flow may comprise at least one driver, which is arranged in the conveying direction behind a subsequent behind the second location transport path. It is provided in particular that the means for maintaining a desired mass flow comprise two drivers, between which the band can be conveyed in the form of a loop. In this case, a movable roller (in particular a dancer roller or a loop lifter) can be arranged between the two drivers for the deflection of the belt in the direction of its normal.

Furthermore, it may alternatively be provided that the driver is designed in the form of an S-roller set. A roll of the S-roll set may be slidable in the horizontal direction.

Furthermore, it can be provided that at least one driver is formed by the rolls of a roll stand.

The means for maintaining a desired mass flow and for setting a required for the liquid feed strip tension of almost zero may further comprise at least one driver, which is arranged in the conveying direction in front of the subsequent behind the second location transport path. This driver may comprise two cooperating rollers, between which the band leaving the solidification section is arranged. The solidification section can be designed as a conveyor belt and the driver can be designed as a roller which presses the belt leaving the solidification section onto a deflection roller of the conveyor belt.

At least one further processing machine may be arranged behind the means for maintaining a desired mass flow. This is, for example, a straightening machine, a rolling mill, a pair of scissors or a reel.

The invention provides facilities and control concepts that largely prevent the negative repercussions from further processing on the cast strip by adjusting and maintaining constant draft and mass flow ratios. This keeps the quality of the cast strip at a high level.

The proposed devices and control concepts to avoid repercussions can consist of two components, namely a strip tension control in combination with a mass flow control.

On the one hand, it is thus possible to ensure that a largely constant strip tension is set in the area of the transport path, the mass flow being constant. The strip tension is preferably greater or almost zero on the transport route.

If a strip tension of greater than zero is set in the transport path, the device for strip tension control ensures that the tension in the area of the casting machine (ie on the solidification section) is practically zero. This is necessary because the cast strip can absorb less and less tensile force with increasing temperature and the allowable train becomes zero in the area of liquid purchasing.

In the drawings, embodiments of the invention are shown. Show it:

Fig. 1 shows schematically an apparatus for producing a tape

Metal with a number of further processing machines,

FIG. 2 is a view similar to FIG. 1, with means for maintaining a desired mass flow or band in a rear region shown in more detail; FIG.

3 an alternative to FIG. 2 embodiment of the device,

4 shows a further alternative embodiment of the device to FIG. 2, FIG.

5 is a view similar to FIG. 1, with means for maintaining a desired mass flow or band in a front area shown in greater detail, FIG.

6 an alternative to FIG. 5 embodiment of the device,

7 shows a further embodiment of the device with indication of the variables to be controlled,

Fig. 8a shows the course of the tension in the band over time without the use of the proposal according to the invention and

Fig. 8b shows the course of the tension in the band over time when using the proposal according to the invention.

FIG. 1 shows a device for producing a strip 1 by a casting process. An essential component of the device is a solidification section 3, which is designed as a conveyor belt 18, which by means of two Um- guide rollers 13 is held in the position shown, wherein the upper side of the conveyor belt 18 is moved in a conveying direction F. At a front in the conveying direction, first place 4 liquid metal from a task vessel 2 on the conveyor belt 18, that is applied to the solidification section 3. In the course of the promotion, the material solidifies and leaves at a second location 5, the conveyor belt 18. The cast strip 1 then passes through a transport path 10 to further processing machines 14, 15, 16, 17, in the present case, a straightening machine 14, a rolling mill 15, a pair of scissors 16 and a reel 17 include.

Core component of the present invention are means 6, 7 for maintaining a desired mass flow of the solidification line 3 leaving belt 1 and / or a desired tension in the belt 1. Preferably, a part of the means 6 in the conveying direction F behind the transport path 10 and part of the means 7 before the transport section 10, but arranged behind the second location 5.

The means 6, 7 are suitable for ensuring that regardless of the process steps that take place in the further processing machines 14, 15, 16, 17, no feedback on the process of strip casting occurs. Rather, the means 6, 7 ensure that a constant mass flow of strip is always drawn off from the solidification section 3 and that the cast strip 1 is then held along the transport path 10 under a predetermined tensile stress.

How this can be done in detail results from FIGS. 2 to 6:

In FIG. 2 it can be seen that the means 6 arranged behind the transport path 10 have two drivers 8 and 9 which can be driven in a regulated manner, wherein a dancer roll or a loop lifter 11 is positioned between the drivers 8, 9. This can deflect the band 1 in the direction of the normal N, so that the band assumes a loop-like shape. In from- As a result of the rotational drive of the drivers 8, 9 and the deflection of the dancer roller 11, it is possible to ensure that irregularities arising from the further processing machines 14, 15, 16, 17 are not transferred to the belt before the means 6. Consequently, the casting process is stabilized and homogenized, so that the casting quality is correspondingly high.

According to this embodiment, the strip tension and mass flow control therefore consists of a system of drivers 8, 9 and a movably mounted roller 11 (loop lifter or dancer roll). This makes it possible to run the subsequent process steps at an adjustable tension level in the belt. In the region of the means 6 for decoupling the train is adjustable and can be adjusted constantly with the position control of the movably mounted roller 11. About a speed control of the driver 8, 9, the loop height is regulated and thus kept constant the mass flow.

The task of the driver 8 or 9 can optionally also be taken over by a rolling stand.

For the mode of operation several variants are possible:

1. If the driver 8 is not driven, it acts as a hold-down roller pair. In this case, in the region of the transport path 10, the same train as on the movable roller 11 (ski jacks, dancer roll).

2. If the driver 8 is driven by a motor in torque control, another train can be set in the area of the transport path 10, with a nearly constant difference between incoming and outgoing train on the driver.

3. If the driver 8 is driven by a motor in speed control, a virtually any other train in the belt can be adjusted in the region of the transport path 10. An alternative to Fig. 2 embodiment of the invention can be seen in Fig. 3. Here is no dancer role between the two drivers 8 and 9 of the means 6. Rather, here by the drive of the driver 8, 9, the conveying of the belt 1 is controlled or regulated so that to compensate for nonuniformities in the mass flow, a sagging, loop-shaped section of the band 1 between the two drivers 8, 9 is used. The tensile and mass torque coupling is thus achieved here by a free loop of the belt with two speed-controlled drivers 8, 9. In contrast to the procedure described in connection with FIG. 2, the process takes place here without an adjustable draft level, the tensile stress is very low over the entire range and results from the weight force of the sagging loop. Mass flow fluctuations are compensated by a change in the loop height on the speed control of the driver 8, 9. The strip tension resulting from the weight of the loop can be picked up by the variable-speed driver 8. This can be set via the driver 8, an almost arbitrary train in the transport path. The function of the driver 9 can optionally be taken over again by a rolling stand.

In Fig. 4, a further alternative can be seen. Here, the tensile and mass torque coupling is achieved by an S-roller set 8 ', 8 "(optionally coupled with a dancer roller) .The lower roller 8" of the S-roller set 8', 8 "can be adjusted in the horizontal direction, which is represented by the With at least one of the speed-controlled S-rollers 8 ', 8 ", the belt tension can be regulated. If a dancer roll is additionally used, it ensures mass flow torque coupling.

In FIGS. 5 and 6, the means 7 are shown in greater detail, which are located in the conveying direction F in front of the transport path 10. The means 7 have in Fig. 5, a driver 12, which consists of two cooperating roles. For train control in the band 1 behind the casting machine (pouring opening 2 together with solidification section 3) thus serves the pair of rollers of the driver 12. Can also be provided a plurality of driver pairs. This ensures that the strip tension in the area of the casting machine is practically zero, which is also necessary in the case of the liquid feed since the strip can not absorb any tensile stresses here. The two rollers of the driver 12 press with defined force on the cast strip to produce the frictional engagement. At least one of the driver rollers is speed-controlled.

Alternatively it can be provided - and this is outlined in Fig. 6 - that the Zugaufnahme takes place via a mounted at the end of the casting machine top roller 12 which presses against one of the deflection rollers 13 of the conveyor belt 18. In this case, a force is applied to the belt and the train is introduced into the speed-controlled top roller 12 or the speed-controlled cast belt.

FIG. 7 shows a further concrete embodiment of the invention. Here, a speed and Bandzugregelung on the type of solution according to the above Figures 2 and 6 is provided. A combination of tension control and mass torque coupling takes place, two drivers 8 and 9 with dancer roller 11 arranged therebetween being provided in the region of the means 6; In the region of the means 7, a driver roller 12 is provided, which presses on a deflection roller 13 of the conveyor belt 18. In this embodiment, the drivers are speed controlled, wherein the driver 9 via the loop control (by means of the dancer roller 11) keeps the mass flow constant. The positioning of the loop lifter (dancer roll 11) keeps the strip tension constant. The driver 8 is speed-controlled with superimposed tension control and ensures a constantly adjustable tension level in the area of the belt transport. The strip tension applied here is introduced via the resting and pressing top roller 12 into the engine torque of the top roller. While in the region of the solidification section 3 there is a strip tension of substantially zero, the strip tension in the region of the transport path 10 is significantly greater than zero. Behind the driver 8 may be an even higher train level.

While the drive roller 12 is speed-controlled while specifying the speed, in the case of the driver 8, a speed specification along with a belt tension input leads to a speed and drive torque and thus tension control. The tension control by means of the dancer roller 11 leads to a regulation of the pivoting angle of the arm on which the dancer roll sits and thus on the regulation of the operating force of the arm to a tension control. Driver 9 is speed-controlled with superimposed loop and thus mass flow control.

FIG. 8 shows the comparison of the time profile of the tensile stress in the band 1 in the region of the belt transport after the casting machine, in FIG. 8a for a previously known solution, in FIG. 8b for an embodiment according to the invention.

The effect on the tension in the belt results from the operation of a pair of scissors 16 (see Fig. 1) in the context of a further processing section. The scissors 16 performs a cut, which results in a deviation from the ideal constant band movement in the band transport. The scissors 16 pulls during the cut namely on the belt 1, so that without the inventive solution according to Fig. 8a high trains in the area of the belt transport occur, which can propagate in the direction of the liquid phase and lead to the problems mentioned above.

Using the solution according to the invention, the strip tension can be kept almost constant with the same disturbance according to FIG. 8b. Disturbances of the casting process can be largely avoided, they are in any case significantly lower than in Fig. 8a. LIST OF REFERENCE NUMBERS

1 band

2 task vessel

3 solidification line

4 first place

5 second place

6, 7 means for maintaining a desired mass flow and tension control

8 drivers

8 "roll of the S roller set

8 "roll of the S roller set

9 drivers

10 transport route

11 movable roller (dancer roll)

12 drivers

13 pulley

14 further processing machine (straightening machine)

15 further processing machine (rolling mill)

16 further processing machine (scissors)

17 further processing machine (reel)

18 conveyor belt

F conveying direction N normal

Claims

claims: 1. A method for producing a strip (1) of metal, in particular of steel, wherein liquid metal from a pouring opening (2) is fed to a solidification section (3) and wherein the cast metal solidifies along the solidification section (3), characterized, that liquid metal is deposited at a first location (4) of the solidification zone (3) formed in the form of a horizontally extending conveying element and that the solidified metal leaves the conveying element (3) at a second location (5) spaced apart in the conveying direction (F), wherein in the conveying direction (F) behind the second location (5) means (6, 7) are provided with which the mass flow of the solidification line (3) leaving the belt and / or the tension in the belt is maintained at a desired value. 2. Method according to claim 1, characterized in that the means (6, 7) at or behind the second location (5) maintain a predetermined tension in the belt (1). 3. The method according to claim 2, characterized in that the means (6, 7) at or behind the second location (5) maintain a temporally nearly constant tension in the belt (1). 4. The method according to any one of claims 1 to 3, characterized in that in the solidification section (3) a voltage of almost zero in the band (1) is maintained. 5. Apparatus for producing a strip (1) from metal, in particular from steel, wherein the device comprises a loading vessel (2), with which liquid metal can be fed to a solidification section (3), the cast metal being deposited on the solidification section (3). is transported in a conveying direction (F) on which it solidifies, in particular for carrying out the method according to one of claims 1 to 4, characterized, in that the solidification zone (3) is designed as a conveying element extending in the horizontal direction, wherein the liquid metal can be deposited at a first location (4) of the solidification section (3), the solidified metal contacting the conveying element (3) in a conveying direction (F) can leave the second spaced place (5) and wherein in the conveying direction (F) at or behind the second location (5) means (6, 7) for maintaining a desired mass flow of the solidification line (3) leaving belt (1) and / or a desired voltage in the band (1) are present. 6. Apparatus according to claim 5, characterized in that the means (6, 7) for maintaining a desired mass flow comprise at least one driver (8, 9), in the conveying direction (F) behind a behind the second location (5) subsequent transport path (10) is arranged. Device according to Claim 6, characterized in that the means (6, 7) for maintaining a desired mass flow comprise two drivers (8, 9) between which the band (1) can be conveyed in the form of a loop. 8. Apparatus according to claim 7, characterized in that between the two drivers (8, 9) a movable roller (11) for deflecting the tape in the direction of its normal (N) is arranged. 9. Apparatus according to claim 6, characterized in that the driver (8) in the form of an S-roller set (8 \ 8 ") is formed. 10. The device according to claim 9, characterized in that a roller (8 ") of the S-roller set (8 ', 8") is arranged displaceably in the horizontal direction. 11. The device according to claim 6, characterized in that the at least one driver (8, 9) is formed by the rollers of a rolling stand. 12. The device according to claim 6, characterized in that the means (6, 7) for maintaining a desired mass flow comprises at least one driver (12) in the conveying direction (F) in front of behind the second place (5) subsequent Transport path (10) is arranged. 13. The apparatus according to claim 12, characterized in that the driver (12) comprises two cooperating rollers between which the solidification line (3) leaving the belt (1) is arranged. 14. The apparatus according to claim 12, characterized in that the solidification section (3) is designed as a conveyor belt (18) and the driver (12) is designed as a roller, which is the solidification section (3) leaving belt (1) on a deflection roller (13) of the conveyor belt (18) presses. 15. Device according to one of claims 5 to 14, characterized in that behind the means (6, 7) for maintaining a desired mass flow at least one further processing machine (14, 15, 16, 17) is arranged. 16. The apparatus according to claim 15, characterized in that behind the means (6, 7) for maintaining a desired mass flow at least one straightening machine (14) is arranged. 17. The apparatus of claim 15 or 16, characterized in that behind the means (6, 7) for maintaining a desired mass flow at least one rolling mill (15) is arranged. 18. The apparatus of claim 15, 16 or 17, characterized in that behind the means (6, 7) for maintaining a desired mass flow at least one pair of scissors (16) is arranged. 19. Device according to one of claims 15 to 18, characterized in that behind the means (6, 7) for maintaining a desired Mass flow at least one reel (17) is arranged. 20. Device according to one of claims 15 to 18, characterized in that behind the means (6, 7) for maintaining a desired mass flow at least one stacking plant is arranged for stacking tape sections.