Casting and rolling plant and method for producing a steel strip

Description

[0001] The invention relates to a casting and rolling plant for producing a steel strip according to the preamble of claim 1, and a corresponding method according to the preamble of claim 9.

[0002] A technology (device and method) for producing cast strips from molten metal is known in the art, for example from WO 2014 / 049150 A1. In this process, molten metal passes through a casting gap defined by two counter-rotating casting rollers and is thereby formed into the cast strip. When casting molten metal on such devices, also known as "twin-roller casting machines," two axially parallel and internally cooled casting rollers rotate in opposite directions, defining the longitudinal sides of a casting gap between them. The casting gap is typically sealed at its narrow sides by plates made of a refractory material. Sufficient molten metal is poured into the casting gap to form a so-called "molten pool" above it, which is maintained until the casting process is complete.The molten metal flowing from the melt pool onto the casting rolls solidifies into individual shells, which are then conveyed by the respective casting roll into the casting gap. In the casting gap, the shells are pressed against each other, forming the cast strip from them and the molten metal trapped between them. The cast strip, emerging continuously from the casting gap in this way, is drawn off below the casting rolls and fed to the rolling mill at a lower level for further processing.

[0003] Other conventional casting and rolling plants with associated processes for producing steel strips are known, for example, from EP 2162251 B1 or CN 112522575 A.

[0004] A conventional casting and rolling mill, representing the state of the art, is essentially simplified in its side view by Fig. 8 The image shows a typical production plant for steel strip. The height difference between the casting rollers of the twin roller and the mill floor is, for example, 5000 mm.

[0005] Such a conventional plant according to Fig. 8 This approach has the disadvantage that, with regard to the casting equipment used, the position of the axes of its casting rollers – viewed vertically – is always significantly higher than the roll gap entry of a rolling mill directly connected to the casting equipment. Consequently, existing solutions suffer from the drawback that, due to the different heights of the casting plant and the rolling mill, the costs for building construction, foundations, and the associated steel structures (e.g., for supporting the continuous casting plant) represent a comparatively large factor in the investment for a new plant or the expansion of existing steelworks. The associated crane systems, lighting, ventilation, access, and transport routes for equipment are also adversely affected by the height and arrangement of the equipment.For the operating personnel (maintenance, repair and operation of the plant), the use of necessary stairways, the use of decentralized operating points and the limited access routes for the delivery of operating resources due to the existing differences in height of the plants are also a constant hindrance to the pending work tasks and lead to adversely high operating costs.

[0006] From WO 2004 / 007118 A1 a casting and rolling plant is known in which a rolling stand is arranged relative to the casting device in such a way that a roll gap inlet of the rolling stand - viewed in the vertical direction - is located below it with respect to the position of the axes of the casting rolls.

[0007] A casting and rolling plant according to the preamble of claim 1 is known from WO 2009 / 021280 A1.

[0008] Accordingly, the invention is based on the objective of optimizing a casting and rolling plant and an associated process for producing a steel strip, thereby reducing both the required construction / manufacturing costs (CAPEX) of the overall plant and its ongoing operating costs (OPEX) for the production of steel strips.

[0009] The aforementioned problem is solved by a casting-rolling plant having the features of claim 1 and by a method having the features of claim 9. Advantageous embodiments of the invention are defined in the dependent claims.

[0010] A casting and rolling plant according to the present invention serves to produce a steel strip that passes through the casting and rolling plant in a conveying direction. Such a casting and rolling plant comprises a casting device, which is designed in the form of a two-roll casting device and accordingly has two casting rolls, each rotatably mounted about axes aligned parallel to each other and at the same height, wherein a cast steel strip is produced by means of the two-roll casting device, and a rolling stand downstream of the casting device in the conveying direction for rolling the cast steel strip.

[0011] According to one embodiment of the invention, in such a casting-rolling plant, the rolling stand is arranged relative to the casting device in such a way that a roll gap entry of the rolling mill - viewed in the vertical direction - is at the same level or above the position of the axes of the casting rolls.

[0012] In The invention also provides a method for producing a steel strip, which can be carried out using a casting-rolling plant as described above. In this method, a steel strip is cast by a casting device in the form of a two-roll casting unit and then moved in a conveying direction to a downstream rolling stand for rolling the cast steel strip. A loop formed by the cast steel strip between the casting device and the rolling stand is preferably controlled and adjusted to a predetermined contour or position. In this method, the rotational speed of the casting rollers about their axes is selected such that the resulting casting speed for the cast steel strip is between 20 and 100 m / min.

[0013] The invention is based on the essential insight that, in a casting-rolling plant, the characteristic positioning or arrangement of a rolling stand provided directly following the casting device relative to the position of the axes of its casting rollers advantageously reduces the resulting overall height of such a plant.

[0014] The method according to the invention is characterized in that a predetermined contour or position is always achieved or set for a loop formed by the cast steel strip between the casting device and the rolling stand, in particular by a suitable adjustment or control of a rotational speed of the casting rolls and / or a rolling speed of the rolling stand, in order to achieve both a high operational reliability of the plant and a high production quality for the produced steel strip.

[0015] In In a further advantageous embodiment of the invention, the casting rollers are designed such that the width of the steel strip cast with them is ≤ 2,200 mm. In other words, a steel strip with a width of up to 2,200 mm can be cast using such designed casting rollers.

[0016] In an advantageous embodiment of the invention, the casting rollers are designed such that their diameter is ≤ 1,500 mm. In this context, it should be noted that the two casting rollers, which are part of a two-roller casting device, expediently have the same diameter.

[0017] In an advantageous embodiment of the invention, a loop detection device is provided by means of which the position of the cast steel strip and a loop formed therein, located between the casting device and the rolling stand, can be determined. Such a loop detection device comprises at least one non-contact distance sensor, which can be in the form of a laser and / or a video camera. In any case, by means of such a loop detection device, it is possible, during operation of the casting-whitening plant according to the invention or during the execution of the method according to the invention, to suitably detect or recognize the contour of a loop formed by the cast steel strip between the casting device and the rolling stand. As already explained elsewhere, by means of a suitable setting or…By controlling the rotational speed of the casting rollers and / or the rolling speed of the rolling stand, a predetermined contour in relation to this loop can be realized.

[0018] In In an advantageous further development of the invention, a control unit is provided which is connected to the loop detection device via a signal connection. The control unit is programmed in such a way that the rotational speed of the casting rolls and / or the rolling speed of the rolling stand can be controlled so that the loop formed by the cast steel strip assumes a predetermined contour.

[0019] Taking into account the aforementioned control unit, the method according to the invention achieves that, depending on the contour or position of the loop formed by the cast steel strip detected by the loop detection device, a rotational speed of the casting rollers and / or a rolling speed of the rolling stand are controlled, set or changed, so that the resulting loop formed by the cast steel strip assumes a predetermined contour.

[0020] Further advantages of the present invention consist of the following aspects or features: Cost reduction in the construction and manufacturing costs of the plants, particularly through a reduction in the required hall height. Installation of the casting plant and a downstream rolling mill on a common level, for example in the form of a furnace floor or a suitable work platform, thereby reducing construction costs and also resulting in lower operating costs later on. Further reduction in operating costs. If the production of liquid steel for supplying the casting plant in the form of a twin-roller casting plant is achieved, for example, via several smaller induction furnaces (preferably with a capacity of 5-10 tons), then the upstream area for the steelmaking process can also be lowered to a lower height level for the entire hall structure (steelworks, twin roller, and rolling mill).

[0021] Exemplary embodiments of the invention are described in detail below with reference to a schematically simplified drawing. The drawing shows: Fig. 1 schematically shows a casting-rolling plant for producing a steel strip according to a first embodiment of the invention; Fig. 2 schematically shows further details of the casting-rolling plant. Fig. 1 , namely with regard to an arrangement of the associated casting device and a rolling mill downstream in the conveying direction relative to each other, Fig. 3 schematically shows the casting device of the plant of Fig. 1 For the production of a strip-shaped material from molten steel, Fig. 4 schematically shows the arrangement of a casting device and a rolling stand downstream in the conveying direction relative to each other for a casting-rolling plant according to a second embodiment of the invention, Fig. 5 schematically shows the arrangement of a casting device and a rolling stand downstream in the conveying direction relative to each other for a casting-rolling plant according to a third embodiment of the invention, Fig. 6 schematically shows a loop detection device with which a casting-rolling plant according to the invention can be equipped, and Fig. 7 schematically shows further details with regard to a possible supply of liquid steel to the casting device of a casting-rolling plant according to the invention.

[0022] The following are, with reference to the Fig. 1-7 Preferred embodiments of a device 10 according to the invention and a corresponding method for producing a steel strip are described. Identical features in the drawing are identified by the same reference numerals. It should be noted that the drawing is simplified and, in particular, not to scale.

[0023] Fig. 1 schematically shows a side view of a casting and rolling plant 10 according to the invention, with which a steel strip 1 can be produced.

[0024] The casting-rolling system 10 comprises a casting device 12, which is designed as a two-roll casting device and accordingly has two casting rollers 13. The casting rollers 13 are each rotatably mounted about axes (X1, X2) that are aligned parallel to each other and at the same height (see figure). Fig. 3 ).

[0025] A casting gap G forms between the casting rollers 13, which is shown in the front view of the casting rollers 13. Fig. 3 This can be seen. To provide a liquid steel melt, plant 10 of Fig. 1 A ladle 2 and an intermediate container 3 are provided, wherein liquid molten steel is introduced from above into the casting gap G via an outlet of the intermediate container 3. Through this casting gap G, the liquid molten steel can then flow vertically downwards to solidify into a cast steel strip 1.

[0026] Furthermore, the casting and rolling plant 10 includes a rolling stand 14 downstream of the casting device 12 in the conveying direction F for rolling the cast steel strip 1.

[0027] After exiting the casting gap G, the cast steel strip 1 is moved through the casting-rolling machine 10 in a conveying direction. This conveying direction is specified in the Fig. 1 symbolized by an arrow and labelled "F".

[0028] The transport of the cast steel strip 1 through the rolling stand 14 is ensured by drivers T, which - viewed in the conveying direction F - are arranged upstream and downstream of the rolling stand 14.

[0029] Downstream of the rolling stand 14, the casting and rolling plant 10 according to the invention is further equipped with a cooling section 24, at least one shear 26 and a final reel 28, on which the produced steel strip 1 can be wound up in a known manner.

[0030] Between the casting device 12 and the rolling stand 14 downstream in the conveying direction F, the casting-rolling plant 10 according to the invention has at least one reversing roller 16. This reversing roller 16 is arranged such that it deflects the cast steel strip 1 in the direction of the rolling stand 14.

[0031] The aforementioned turning roller 16 is important insofar as the cast steel strip 1, after exiting vertically downwards from the casting gap G, initially assumes the form of a loop 19, which is formed by the cast steel strip 1 between the casting device 12 and the rolling stand 14. This loop 19 is then deflected horizontally towards the rolling mill 14 in a controlled manner by means of the turning roller 16. It is important that the turning roller 16 is located at approximately the same height as a roll gap entry of the rolling stand 14, so that the turning roller 16 enables the steel strip 1 to enter the roll gap entry of the rolling stand 14 horizontally.

[0032] With regard to the casting-rolling plant 10 according to the invention, it should be emphasized that its essential components are formed by the casting device 12 and the downstream rolling stand 14. Of essential importance of the present invention – viewed in the vertical direction – is the arrangement of the casting device 12 and the rolling stand 14 relative to each other. This is described below with reference to the Figuren 2 , 4 und 5 explained in detail.

[0033] Fig. 2 Figure 1 illustrates an arrangement of the casting device 12 and the rolling stand 14 relative to each other, according to a first embodiment of the invention. The casting device 12 and the rolling stand 14 are each mounted or installed on a common foundry floor H (or a comparable area). The axes X1, X2 of the casting rolls 13 are spaced a distance a from the foundry floor H, and a roll gap entry 15 of the rolling stand 14 is spaced a distance b from the foundry floor.

[0034] In the first embodiment according to Fig. 2 If the two distances a and b each assume the same value, i.e., if the axes X1, X2 of the two casting rolls 13 on the one hand and the roll gap entry 15 of the rolling stand 14 on the other are each equidistant from, or positioned above, the furnace floor H, then the roll gap entry 15 of the rolling mill 14 – viewed vertically – is at the same height as the axes X1, X2 of the casting rolls 13. It is also important that the turning roll 16, as already explained, is located at approximately the same height as the roll gap entry 15 of the rolling mill 14. Thus, with respect to the axes X1, X2 of the casting rolls 13 and the roll gap of the rolling stand 14, the same level is achieved – viewed vertically.

[0035] Fig. 4 Figure 1 illustrates an arrangement of the casting device 12 and the rolling stand 14 relative to each other, according to a second embodiment of the invention. Here, the distance a, by which the axes X1, X2 of the casting rolls 13 are spaced from the foundry floor H, is chosen to be greater than the distance b, by which the roll gap entry 15 of the rolling stand 14 is spaced from the foundry floor H. Consequently, the roll gap entry 15 of the rolling stand 14 – viewed in the vertical direction – is located below the position of the axes X1, X2 of the casting rolls 13. This, in turn, results in the distance s of the roll gap entry 15 from the position of the axes X1, X2 – viewed in the vertical direction – assuming a distance that satisfies the following condition: s ≤ 2 × D , mit D = Durchmesser einer Gießrolle 13 .

[0036] The diameter of a casting roller is in the Fig. 3 illustrated.

[0037] In the representation of the second embodiment according to Fig. 4 The distance s is approximately half the diameter of a casting roll, i.e., s = 0.5 x D. For this second embodiment, it is important that the arrangement of the casting device 12 and the rolling stand 14 relative to each other is chosen such that the distance s, as explained, does not exceed twice the diameter of a casting roll 13.

[0038] Fig. 5 Figure 1 illustrates an arrangement of the casting device 12 and the rolling stand 14 relative to each other, according to a third embodiment of the invention. Here, the distance a, by which the axes X1, X2 of the casting rolls 13 are spaced from the foundry floor H, is chosen to be smaller than the distance b, by which the roll gap entry 15 of the rolling stand 14 is spaced from the foundry floor H. In As a result, the roll gap inlet 15 of the roll stand 14 is located above it in the vertical direction with respect to the position of the axes X1, X2 of the casting rolls 13.

[0039] It should be specifically noted here that in the second and third embodiments in the Fig. 4 und 5 Neither the complete loop 19 of the cast steel band 1 nor the turning roller 16 are shown for the sake of simplicity.

[0040] In With reference to the aforementioned first, second and third embodiments of the casting-rolling plant 10 according to the invention, it is specifically pointed out here that the characteristic arrangement of the casting device 12 and the rolling stand 14 relative to each other results in a reduction of the height difference (cf. Fig. 2 ) or even a complete elimination (cf. Fig. 2 This height difference between the axes of rotation of the casting rolls 13 and the roll gap entry of the downstream rolling stand 14 is achieved. This advantageously results in a lower overall height for the casting-rolling plant 10 and a smaller vertical distance between the casting unit 12 and the rolling stand 14 and a common foundry floor H. As explained at the outset, this reduces the required hall height and further lowers construction costs for the casting-rolling plant 10.

[0041] In the Fig. 6 and 7 Further options are shown and explained which may be provided in the same way in the first, second and third embodiments of the casting-rolling plant 10 according to the invention.

[0042] According to the presentation of Fig. 6 A loop detection device 18 is preferably arranged adjacent to an underside of the casting device 12, by means of which the position of the cast steel strip 1 and the loop 19 formed therein, located between the casting device 12 and the rolling stand 14, can be determined. Such a loop detection device 18 comprises at least one non-contact distance sensor 20, which may be in the form of a laser and / or a video camera.

[0043] In conjunction with the loop detection device 18, the casting-rolling plant 10 is designed according to Fig. 6 furthermore, it is equipped with a control unit R, which is connected to the loop detection device 18 via a signal connection. Accordingly, by means of the control unit R and depending on the contour or position of the loop 19 formed by the cast steel strip 1 detected by the loop detection device 18, it is possible to control and adjust the rotational speed of the casting rolls 13 and / or the rolling speed of the rolling stand 14 so that the resulting loop 19 formed by the cast steel strip 1 assumes a predetermined contour.

[0044] According to the presentation of Fig. 7 Instead of a ladle 1, is it possible that – viewed in the conveying direction F – the process upstream of the casting device 12 takes place through at least one induction furnace 22? In such an induction furnace 22, the starting material 4, for example scrap metal, is heated and melted. The resulting molten steel 5 is then suitably introduced from above into the casting gap G of the casting device 12, which is formed between the two casting rollers 13.

[0045] In the representation of Fig. 7 Two such induction furnaces 22 are shown, with which, as explained, a molten steel can be provided or generated for the casting device 12. Alternatively, instead of showing Fig. 7It is also possible to provide only one induction furnace 22. Regardless of the number of such induction furnaces 22, it should be emphasized for the present invention that this achieves a further advantageous reduction in the overall height of the casting-rolling plant 10 or its height above a foundry floor H or the like. Reference symbol list

[0046] 1 Steel strip 2 Pan 3 Intermediate container 4 Raw material 5 Steel melt 10 Casting and rolling plant 12 Casting device 13 Casting roll 14 Rolling stand 15 Roll gap inlet 16 Turning roll 18 Loop detection device 19 Loop (formed by a cast steel strip 1) 20 Non-contact distance sensor 21 Signal section 22 Induction furnace 24 Cooling section 26 Shear 28 Reel Diameter (of a casting roll 13) Conveyor direction G Casting gap H Mill floor R Control unit Distance - viewed in the vertical direction - between roll gap inlet 15 and axis (X1, X2) of a casting roll 13 T Driver X1, X2 Axis (of a casting roll 13)

Claims

1. Casting and rolling plant (10) for producing a steel strip (1), which transits the casting and rolling plant (10) in a conveying direction (F), comprising: a casting device (12) which is constructed in the form of a double-roller casting device (12) and correspondingly comprises two casting rollers (13) which are arranged to be respectively rotatably mounted about axes (X1, X2) oriented axially parallel to one another and at the same height, wherein a cast steel strip (1) is produced by means of the double-roller casting device (12), and a roll stand (14), which is downstream of the casting device (12) in conveying direction (F), for rolling the cast steel strip (1), characterised in that the roll stand (14) is so arranged relative to the casting device (12) that a rolling gap inlet (15) of the rolling mill (14) as seen in vertical direction is disposed with respect to the position of the axes (X1, X2) of the casting rollers (13) at the same height as or above the casting rollers.

2. Casting and rolling plant (10) according to claim 1, characterised in that at least one turning roller (16) by which the cast steel strip (1) is deflectable in the direction of the roll stand (14) is arranged between the casting device (12) and the roll stand (14) downstream thereof in conveying direction (F).

3. Casting and rolling plant (10) according to one of the preceding claims, characterised in that the casting rollers (13) are such that a width of the steel strip (1) cast therewith is ≤ 2.200 mm.

4. Casting and rolling plant (10) according to any one of the preceding claims, characterised in that a diameter of the casting rollers (13) is ≤ 1.500 mm.

5. Casting and rolling plant (10) according to any one of the preceding claims, characterised by a loop detection device (18) by means of which a position of the cast steel strip (1) and a loop (19), which is formed by that and present between the casting device (12) and the roll stand (14), is determinable.

6. Casting and rolling plant (10) according to claim 5, characterised in that the loop detection device (18) comprises at least one contactless distance sensor (20), preferably in that the distance sensor (20) is constructed in the form of a laser and / or a video camera.

7. Casting and rolling plant (10) according to claim 5 or 6, characterised by a regulating unit (R) which is in signal connection with the loop detection device (18), wherein the regulating unit (R) is so arranged with respect to programming that a rotational speed of the casting rollers (13) and / or a rolling speed of the roll stand (14) are regulable in controlled manner by the unit in such a way that the loop (19) formed by the cast steel strip (1) adopts a predetermined contour.

8. Casting and rolling plant (10) according to any one of the preceding claims, characterised by at least one induction furnace (22) which is preferably arranged above the casting device (12) and which serves the purpose of feeding liquid steel melt into a casting gap (G) formed between the casting rollers (13).

9. Method for producing a steel strip by a casting and rolling plant (10) according to any one of claims 1 to 8, in which a steel strip (1) is cast by a casting device (12) in the form of a double-roller casting device (12) and is subsequently moved in a conveying direction (F) to a downstream roll stand (14) for rolling of the cast steel strip (1), wherein a loop (19) formed by the cast steel strip (1) between the casting device (12) and the roll stand (14) is set in a preferably regulated manner to a predetermined contour or position, characterised in that a rotational speed of the casting rollers (13) about the axes (X1, X2) thereof is so selected that the thereby-resulting casting speed for the cast steel strip (1) adopts a value between 20 and 100 m / min.

10. Method according to claim 9, characterised in that for setting the loop (19), which is formed by the cast steel strip (1), to a predetermined contour a rotational speed of the casting rollers (13) and / or a rolling speed of the roll stand (14) is or are changed.

11. Method according to claim 9 or 10, characterised in that a contour of the loop (19) formed by the cast steel strip (1) is detected by means of a loop detection device (18).

12. Method according to claim 11, characterised by a regulating unit (R) which is in signal connection with the loop detection device (18), wherein by means of the regulating unit (R) and in dependence on the contour or position, which is detected by the loop detection device (18), of the loop (19) formed by the cast steel strip (1) a rotational speed of the casting rollers (13) and / or a rolling speed of the roll stand (14) is or are set or changed in regulated manner so that the resulting loop (19) formed by the cast steel strip (1) thereby adopts a predetermined contour.