Method and device for producing a metallic strip in a continuous casting and rolling process

Abstract

A method for producing a metallic strip by continuous casting-rolling, wherein a slab is cast in a casting machine and then sent to a finishing mill located downstream, relative to the transport direction of the strip. In the event that the transport of the slab or strip comes to a complete or substantially complete standstill, the following steps are carried out: (a) cutting through the strip at a first point; (b) cutting through the strip at a second point that is 0.1-5.0 m upstream from the first point; (c) removing the cut-out piece of strip to create a gap in the strip; (d) conveying new strip material into the area of the gap from the area located upstream of the first point; and (e) cutting off pieces of the new strip material conveyed from upstream according to step (d) and removing the pieces from the transport line.

Claims

1. A method for producing a metallic strip by a continuous casting-rolling process, comprising the steps of: casting a slab in a casting machine; sending the slab to a finishing mill located downstream, relative to a transport direction of the strip, and rolling the strip; upon occurrence of a breakdown where transport of the slab or strip has come to a complete or substantially complete standstill, the following steps are carried out: (a) cutting through the strip at a first point using a separating device that is pivotable about an axis transverse to the transport direction; (b) pivoting the separating device in a direction opposite the transport direction and cutting through the strip at a second point that is 0.1-5.0 m upstream, relative to the transport direction, from the first point using the separating device to create a cut-out piece; (c) removing the cut-out piece of strip from the strip to create a gap in the strip; (d) conveying new strip material into an area of the gap from an area located upstream, relative to the transport direction, of the first point; and (e) cutting off pieces of the new strip material conveyed from upstream according to step (d) and removing the pieces from the new strip material, wherein the cutting off pieces of new strip material is carried out using the separating device.

2. The method according to claim 1, wherein the first and second points lie between the casting machine and the finishing mill.

3. The method according to claim 2, wherein the first and second points lie between a roughing mill following immediately after the casting machine in the transport direction and a furnace following the roughing mill in the transport direction.

4. The method according to claim 2, wherein the first and second points lie between a furnace following the casting machine in the transport direction and the finishing mill.

5. The method according to claim 1, wherein the separating device is an oscillating shear or a movable gate shear.

6. The method according to claim 1, wherein steps (d) and (e) are repeated until the casting machine has been freed of strip material or until a section of defined length in the casting machine is free of strip material.

7. The method according to claim 1, wherein steps (a)-(c) are performed by a first separating device, and steps (d) and (e) are performed by a second separating device, wherein the two separating devices are arranged at different locations relative to the transport direction.

8. The method according to claim 1, wherein strip material is conveyed out of the finishing mill opposite the transport direction into an area of at least one separating device, and pieces of the conveyed strip material are cut off in the at least one separating device and removed from the transport line.

9. The method according to claim 8, further including arranging a device next to the at least one separating device that applies a straightening force to the strip material, which force is perpendicular to a surface of the strip material.

10. The method according to claim 1, wherein the gap is produced by more than two cuts of the separating device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a schematic diagram of a casting-rolling installation for the production of steel strip;

(2) FIG. 2 shows a section of the strip with a separating device in the form of an oscillating shear during a first substep of the proposed method;

(3) FIG. 3 shows the section of the strip with the separating device during a second substep of the proposed method;

(4) FIG. 4 shows the section of the strip with the separating device during a third substep of the proposed method;

(5) FIG. 5 shows the section of the strip with the separation device during a fourth substep of the proposed method;

(6) FIG. 6 shows the section of the strip with the separation device during a fifth substep of the proposed method;

(7) FIG. 7 shows the section of the strip with the separation device during a sixth substep of the proposed method;

(8) FIG. 8 shows the section of the strip with the separation device during a seventh substep of the proposed method;

(9) FIG. 9 shows the section of the strip with the separation device during an eighth substep of the proposed method;

(10) FIG. 10 shows the section of the strip with the separation device during a ninth substep of the proposed method; and

(11) FIG. 11 shows the section of the strip with the separation device during a tenth substep of the proposed method.

DETAILED DESCRIPTION OF THE INVENTION

(12) FIG. 1 shows a sketch of an example of a casting-rolling installation, which is designed as a fully continuous installation and which comprises as its central elements a casting machine 2 and a finishing mill 3. Downstream from the casting machine 2 is a roughing mill 7, to which, depending on the plant design, a furnace 8 (connecting roller table with heating function) is connected. Downstream from the furnace 8 is the finishing mill 3. Downstream from the finishing mill 3 is a cooling section 12 and a flying shear 13. Next in the transport direction F is at least one coiler 14, 15.

(13) Between the roughing mill 7 and the furnace 8, a first separating device 9 for the strip 1 in the form of an oscillating shear is arranged. A second separating device 10 of the same type is located between the furnace 8 and the finishing mill 3.

(14) Naturally, the proposed method can also be used in a different type of casting-rolling installation.

(15) By the use of sensors (not shown), the complete installation is monitored by a central fault reporting system 16.

(16) During endless rolling, the installation is completely filled by a strand, that is, by a continuous strip 1. When a breakdown occurs, the strand or the strip comes to a stop. Because of the length of the installation, the operating personnel cannot see the entire line. A problem occurs in only one part of the installation and usually triggers an immediate stop of this part. This leads to an uncontrolled backup of material or to traction on the material in the other parts of the installation if a controlled stop at a suitable deceleration rate is not initiated in these other parts. As a result, damage can be caused to various parts of the installation. In addition, a material backup can develop, and until it has been corrected it is impossible for production to continue.

(17) Because all of the parts of the installation are connected, stopping the material means that the entire strand or strip 1 can no longer move. According to the invention, a gap is intentionally produced, so that the slab will be able to move again. In addition, the casting machine 2 must be freed of material as quickly as possible so as not to freeze. It should also be possible to send as much as possible of the still-usable material present in the installation to further processing.

(18) The inventive solution proceeds on the basis of the following units in the installation:

(19) As described above, the installation is configured essentially as shown in FIG. 1. A typical element of a fully continuous casting-rolling installation of this type is the central fault reporting system 16 and the separating devices 9, 10, and 13.

(20) All of the fault reports are collected in the higher-level central fault reporting system 16, so that the necessary measures can be implemented effectively in the concrete case.

(21) The separating device 9 situated upstream relative to the transport direction F is designed as, for example, an oscillating shear or a movable gate shear. The separating device 9 has the property of being able to make, in a short time, several separating cuts in stationary and/or moving material at positions within the separating device which differ in the transport direction. The separating device also comprises a scrap discharge system 17 (see, for example, FIG. 2).

(22) It is advantageous into another separating device 10, which is arranged downstream from the furnace 8 and upstream from the finishing mill 3; this separating device 10 is therefore downstream from the separating device 9 in the production line, but it can be designed in exactly the same way as the separating device 9, including the scrap discharge system 17.

(23) Devices are provided in the casting machine 2, furthermore, which make it possible to bring the casting process to a standstill quickly and which allow the cast strand to be transported again after a defined maximum period of time.

(24) The central fault reporting and response system 16, which it is advantageous to provide, covers the entire installation. If, for example, a material flow problem occurs in the finishing mill 3 or if such a problem becomes evident, a signal must be transmitted immediately to all of the other units and controls in the installation, so that the individual units and drives can be stopped simultaneously in a controlled manner.

(25) After the signal fault has been sent, the casting machine 2 is also stopped in a controlled manner; that is, no more molten steel may be allowed to enter the mold, and the machine must be brought to a standstill.

(26) A fault is detected either by suitable sensors (speed indicators, strip tension meters, loop lifters, etc.) of the installation's automation system or by the operating personnel in one of the areas of the installation.

(27) The proposed method and the installation equipment necessary to implement it are provided to allow the separation of a stationary or nearly stationary material strand (transport speed of less than 1 m/min) in a short time and thus to make it possible to empty the casting machine 2.

(28) The specific sequence of steps of the method is illustrated by way of example in FIGS. 2-11. The essential idea here is to create the possibility of cutting a gap in the stationary material or strip 1. This gap makes it possible to resume the transport of the strip, so that the strip material can be chopped into scrap and removed from the installation.

(29) FIG. 2 shows a separating device 9, 10. This could represent, for example, the second separating device 10. The separating device is designed as an oscillating shear.

(30) The shear carrier 18 of the oscillating shear 10 is first pivoted as illustrated in FIG. 2 (around an axis perpendicular to the plane of the drawing in FIG. 2), so that the shearing elements 19 and 20 are located at a first point 4 of the installation. The strip 1 is completely at rest here; that is, the transport speed in the transport direction is therefore, in practice, zero.

(31) In FIG. 3 we see how the shearing elements 19, 20 have been moved toward each other to cut through the strip 1 at the first point 5. The shearing elements 19, 20 are then moved back away from each other againas shown in FIG. 4; the strip 1 is now separated at the first point 4.

(32) Now, as can be seen in FIG. 5, the shear carrier 18 is pivoted so that the shear elements 19, 20 arrive at a second point 5 of the installation. Now, according to FIG. 6, another cut is made, and thus a piece 21 of strip is cut away from the strip 1. The first and second points 5, 4 are usually 0.2-1.5 m apart from each other.

(33) This piece 21 falls down into the area of a scrap discharge system 17 (shown only in highly schematic fashion), as can be seen in FIG. 7. A gap 6 remains in the strip 1.

(34) The strip 1 can now travel from the left into the gap 6 thus created, while the strip 1 on the right remains at rest. This is illustrated in FIG. 8. The strip is fed from the casting machine 2 into the gap at a creep, and thus the chopping operation starts, by which the strip 1 coming from the left is cut into pieces 21 and then removed from the area of the casting machine 2.

(35) As can be seen in FIG. 9, another piece 21 is cut out after a sufficient amount of strip, coming from the left, has arrived in the area of the gap 6. After the piece 21 has been cut off, as can be seen in FIG. 10, the gap 6 is again available for the chopping-off of additional strip material.

(36) The chopping process continues until the strip or slab coming from the casting machine 2 has been cut into pieces 21 and removed by the scrap discharge system 17. In this way, the casting machine 2 is freed of strip material, and as much of the remaining slab as desired is removed.

(37) It can be seen in FIG. 11, furthermore, how the tail end of the still-stationary strip 1 can be straightened in the area on the right of the figure. For this purpose, means 11 for applying a straightening force are provided, so that the tail end of the strip can be straightened. The central part of the means 11 consists of vertically movable rollers, which can press against the surface of the strip.

(38) Depending on the design of the casting installation, the casting process can now resume.

(39) The separating devices 9, 10 can be used alternatively or additively as described.

(40) As a combination variant of the method, it is also possible for the separating device 10 to cut the gap 6, whereas the remaining strand proceeding from the casting machine 2 is chopped into scrap at the separating device 9 and removed by the scrap removal system there.

LIST OF REFERENCE NUMBERS

(41) 1 strip 2 casting machine 3 finishing mill 4 first point 5 second point 6 gap 7 roughing mill 8 furnace 9 first separating device (oscillating shears/gate shears) 10 second separating device (oscillating shears/gate shears) 11 means for applying a straightening force 12 cooling section 13 flying shear 14 coiler 15 coiler 16 fault reporting system 17 scrap discharge system/scrap collector 18 shear carrier 19 shear element 20 shear element 21 piece of strip material F transport direction