This application is a National Stage application of International application PCT/EP2008/009576 filed Nov. 13, 2008 which claims priority of German application DE 10 2007 056 192.1 filed Nov. 21, 2007.
1. Field of the Invention
The invention pertains to a method for manufacturing a strip of metal, particularly of steel, wherein liquid metal is delivered to a solidification section from a pour hole, and wherein the cast metal solidifies along the solidification section. The invention furthermore pertains to a device for manufacturing a strip of metal.
2. Description of the Prior Art
The horizontal strip casting method makes it possible to cast melts of various steel types near-net shape within a strip thickness range of less than 20 mm. Systems of this type that make it possible to manufacture strips have already been described. Lightweight structural steels, in particular, with a high content of C, Mn, Al and Si can be advantageously manufactured in this case.
In the horizontal strip casting of steel, a direct association exists between the material in the liquid phase in the melt delivery region and the further processing steps of the solidified material over the cast strip. After its emergence from the casting machine and the solidification, the cast strip is delivered to the additional processing stations via a transport section. The processing steps may consist of: leveling, rolling, cutting and winding (reeling, coiling).
These or similar components of a complete system may cause tension and mass flow fluctuations in the cast strip. If the disturbances propagate in the direction of the liquid steel, casting defects can occur and the cast strip can be negatively influenced, e.g., in the form of thickness fluctuations, overflowing, edge constrictions and tearing of the strip or flow.
Lightweight structural steels that have a very long solidification interval (i.e., temperature window from the beginning of the solidification from the melt up to the complete solidification and zero-solidity or zero-viscosity temperatures depending thereon), in particular, are also intolerant to fluctuating tensions in the region of the transport section.
The invention therefore is based on the objective of additionally developing a method of the initially described type, as well as a corresponding device, such that it can also be ensured that the cast strip has a high quality if disturbances of the above-described type occur.
With respect to the method, this objective is attained, according to the invention, in that liquid metal is delivered to a first location of the solidification section that is realized in the form of a horizontally extending conveyor element, and that the solidified metal departs the conveyor element at a second location that is spaced apart from the first location in the transport direction, wherein means for maintaining the mass flow of the strip departing the solidification section and/or the tension in the strip at a desired value are provided at or downstream of the second location referred to the transport direction.
The means arranged downstream of the second location preferably maintain a specified tensile stress in the strip. The means may, in particular, maintain a tensile stress in the strip that is constant in time downstream of the second location.
A tensile stress of nearly zero can be maintained in the strip in the solidification section.
The proposed device for manufacturing a strip of metal, particularly of steel, comprises a pour hole for delivering liquid metal to a solidification section, wherein the cast metal is transported in a transport direction on the solidification section and solidifies thereon. According to the invention, the device is characterized in that the solidification section is realized in the form of a horizontally extending conveyor element, wherein the liquid metal can be delivered to a first location of the solidification section, wherein the solidified metal can depart the conveyor element at a second location that is spaced apart from the first location in the transport direction, and wherein means for maintaining a desired mass flow of the strip departing the solidification section and/or a desired tension in the strip are provided downstream of the second location referred to the transport direction.
The means for maintaining a desired mass flow may comprise at least one driver that is arranged downstream of a transport section that is situated downstream of the second location referred to the transport direction. In this context, it is proposed, in particular, that the means for maintaining a desired mass flow comprise two drivers, between which the strip can be transported in the form of a loop. In this case, a movable roll (particularly a dancer roll or loop lifter) may be arranged between the two drivers in order to deflect the strip in the direction of its normal.
Alternatively, it would also be possible to realize the driver in the form of an S-roll set. One roll of the S-roll set may be arranged in a horizontally displaceable fashion.
It would furthermore be possible that at least one driver is formed by the rolls of a roll stand.
The means for maintaining a desired mass flow and for adjusting a strip tension of nearly zero as it is required for the delivery of the liquid metal may furthermore comprise at least one driver that is arranged upstream of a transport section that is situated downstream of the second location referred to the transport direction. This driver may comprise two cooperating rolls, between which the strip departing the solidification section is arranged.
The solidification section may be realized in the form of a conveyor belt and the driver may be realized in the form of a roll that presses the strip departing the solidification section against an idle roll of the conveyor belt.
At least one additional processing machine may be arranged downstream of the means for maintaining a desired mass flow. This machine may consist, for example, of a leveling machine, a rolling mill, shears or a coiler.
The invention proposes devices and control concepts that largely eliminate the negative effects of the additional processing on the cast strip, namely by adjusting and maintaining the tension and the mass flow constant. A high quality of the cast strip can be maintained in this fashion.
The proposed devices and control concepts for avoiding these effects may consist of two components, namely of a strip tension control in combination with a mass flow control.
Consequently, it can be ensured that a largely constant strip tension is adjusted in the region of the transport section, wherein the mass flow is also constant. The strip tension on the transport section preferably is greater than or nearly zero.
If a strip tension greater than zero is adjusted in the transport section, the device for controlling the strip tension ensures that the tension is practically zero in the region of the casting machine (i.e., in the solidification section). This is necessary because the cast strip can absorb less and less tension as the temperature increases and the permissible tension in the region of the melt delivery becomes zero.
Embodiments of the invention are illustrated in the drawings. In these drawings:
a shows the tensile stress in the strip as a function of the time without utilization of the inventive proposal, and
b shows the tensile stress in the strip as a function of the time when utilizing the inventive proposal.
The essential components of the present invention are means 6, 7 for maintaining a desired mass flow of the strip 1 departing the solidification section 3 and/or a desired tension in the strip 1. It is preferred to arrange part of the means 6 downstream of the transport section 10 referred to the transport direction F and part of the means 7 upstream of the transport section 10, however, downstream of the second location 5.
The means 6, 7 are designed for ensuring that the strip casting process is not affected by the processing steps taking place in the additional processing machines 14, 15, 16, 17. The means 6, 7 ensure that a constant strip mass flow is always withdrawn from the solidification section 3 and that a specified tensile stress is subsequently maintained in the cast strip 1 along the transport section 10.
According to
According to this embodiment, the strip tension and mass flow control therefore consists of a system comprising drivers 8, 9 and a movably supported roll 11 (loop lifter or dancer roll). This makes it possible to carry out the ensuing processing steps with an adjustable level of tension in the strip. The tension can be adjusted in the region of the means 6 for decoupling the tension and maintained constant by means of the position control of the movably supported roll 11. The loop height is controlled by controlling the rotational speed of the drivers 8, 9 in order to thusly maintain the mass flow constant.
The function of the driver 8 or 9 may, if so required, also be fulfilled by a roll stand.
The operation can be realized with several variations:
In
Alternatively, it would be possible—as schematically indicated in FIG. 6—to absorb the tension by means of a top-roll 12 that is arranged at the end of the casting machine and presses against one of the idle rolls 13 of the conveyor belt 18. In this case, a force of pressure is exerted upon the strip and the tension is introduced into the speed-controlled top-roll 12 or the speed-controlled cast strip, respectively.
Although the strip tension in the region of the solidification section 3 is essentially zero, the strip tension is significantly greater than zero in the region of the transport section 10. The level of tension may even be higher downstream of the driver 8.
The speed-controlled driver roll 12 operates with a specified speed, but a specified speed together with a specified strip tension in the case of the driver 8 results in a speed and torque control and therefore a tension control. The tension control realized by means of the dancer roll 11 leads to a control of the pivoting angle of the arm, on which the dancer roll is arranged, and therefore to a tension control in the form of a control of the actuating force of the arm. The driver 9 is speed-controlled with superimposed loop control and therefore mass flow control.
The tensile stress in the strip is. affected due to the actuation of shears 16 (see
The shears 16 pull on the strip 1 while the cut is produced such that high tensions that could propagate in the direction of the liquid phase and lead to the initially described problems would occur in the region of the strip transport without the inventive solution according to
According to
Number | Date | Country | Kind |
---|---|---|---|
10 2007 056 192 | Nov 2007 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP2008/009576 | 11/13/2008 | WO | 00 | 6/18/2010 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2009/065517 | 5/28/2009 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4721152 | Reichelt et al. | Jan 1988 | A |
4817702 | Itoyama et al. | Apr 1989 | A |
6192973 | Schwerdtfeger | Feb 2001 | B1 |
6280542 | Cornelissen | Aug 2001 | B1 |
6363997 | Urlau | Apr 2002 | B1 |
6527882 | Wehage | Mar 2003 | B1 |
6907915 | Hohenbichler | Jun 2005 | B2 |
20100059196 | Spitzer | Mar 2010 | A1 |
Number | Date | Country |
---|---|---|
19852275 | May 2000 | DE |
086 215 | Aug 1998 | EP |
62-142004 | Jun 1987 | JP |
62142004 | Jun 1987 | JP |
63049350 | Mar 1988 | JP |
63157750 | Jun 1988 | JP |
02025250 | Jan 1990 | JP |
04197561 | Jul 1992 | JP |
4-305347 | Oct 1992 | JP |
05293602 | Nov 1993 | JP |
05293607 | Nov 1993 | JP |
08090181 | Apr 1996 | JP |
08238516 | Sep 1996 | JP |
08294715 | Nov 1996 | JP |
Number | Date | Country | |
---|---|---|---|
20100252223 A1 | Oct 2010 | US |