Curved segment of a strand guide device

Abstract

The invention relates to an arch segment (160) in the arch region of a strand-guiding device (150) for guiding and deflecting a cast strand (200) made of metal into the horizontal after leaving a mold (140). The arch segment has an upper frame (162) and a lower frame (164), on each of which a plurality of strand-guiding rollers (170) are rotatably mounted. The upper frame and the lower frame are connected together such that the respective strand-guiding rollers thereof are arranged opposite one another in a mutually spaced manner and define an arch-shaped guide channel for guiding the cast strand (200). In order to reduce deformations of the cast strand in the arch region (150-I) of the strand guide, at least one of the strand-guiding rollers (170) on the upper frame and / or the lower frame is designed in the form of an axle roller.

Description

[0001] The invention relates to an arc segment in the arc region of a strand guiding device for guiding and deflecting a cast metal strand into the horizontal after leaving a mold.

[0002] Strand guide devices with curved segments are generally known in the prior art, for example, from German patent application DE 10 2008 009 136 A1. This patent application teaches that each curved segment has an upper frame and a lower frame, on each of which a plurality of strand guide rollers are rotatably mounted. The upper frame and the lower frame are connected to one another, in particular, positioned relative to one another, in such a way that their respective strand guide rollers are spaced apart from one another and span an arcuate guide channel for guiding the cast strand. The individual strand guide rollers on the upper frame and the lower frame can be rotationally driven or not.

[0003] Furthermore, it is known in the state of the art of continuous casting that the cast strand, after leaving the mold, has the tendency to bulge, i.e. to bulge, particularly due to a so-called ferrostatic pressure that prevails inside the strand that has not yet solidified, particularly where it is not prevented from doing so in the strand guide area, for example by strand guide rollers, i.e. particularly in the spaces between two strand guide rollers adjacent in the casting direction.

[0004] The invention is based on the object of developing a known arc segment and a known strand guide with such an arc segment in such a way that bulging of the cast strand in the arc region of the strand guide is reduced.

[0005] European patent application EP 2 682 204 A2 discloses a blocking element for a roll shell of a roll line of a continuous casting plant with a rotatable shaft having a coolant line, wherein the roll shell is arranged such that it is non-rotatably mounted on the rotatable shaft. The roll shell comprises at least one coolant channel arranged such that it is in fluid communication with the coolant line, wherein the coolant channel has at least one fluid inlet and at least one fluid outlet. The blocking element is arranged such that it supplies coolant to the at least one fluid inlet and receives coolant from the at least one coolant outlet.

[0006] German patent application DE 10 2015 202 608 A1 discloses a casting system for casting liquid metal, in particular steel, into a cast strand. The casting system comprises a mold for producing a cast strand from the supplied molten metal and a strand guide for transferring the cast strand to a horizontal position. The strand guide has at least one input roller element arranged downstream of the mold in the casting direction and an output roller element further downstream. In order to manufacture and maintain the strand guide more easily and cost-effectively, the invention proposes that the input roller segment and the output roller segment of the strand guide be constructed identically.

[0007] International patent application WO 2015 / 000968 A1 discloses a casting-rolling plant for producing metallic rolled stock, comprising: a casting line with a mold for vertically casting a cast strand and a strand guide, which has a roller conveyor for deflecting the cast strand from the vertical to the horizontal, a straightening device, a shear for cutting the cast strand into slabs, and an exit roller conveyor. The casting plant further comprises a rolling line arranged parallel and offset to the casting line, with an inlet roller conveyor and a Steckel rolling mill for rolling the slabs into the rolled stock. Furthermore, the plant has a transverse shifting device for transversely transporting the slabs from the exit roller conveyor of the strand guide to the inlet roller conveyor of the rolling line, and a furnace for heating the slabs during transverse transport.The casting and rolling plant is characterized in that the furnace includes the complete transverse displacement device as well as at least part of the exit roller table of the strand guide and at least part of the entry roller table of the rolling line; and that the inlet of the furnace for the slabs is arranged in the casting line and the outlet of the furnace for the slabs is arranged in the rolling line.

[0008] US patent application US 2021 / 0197252 A1 discloses an arcuate strand guide device with strand guide rollers on the inside and outside of the arc, wherein at least some of the strand guide rollers are designed as axle rollers, each having a fixed axis. Claim 1 is defined in relation to this document.

[0009] The invention is based on the object of further developing a known arc segment and a known strand guide comprising such an arc segment, as well as known casting plants each having such a strand guide, such that the distances between each two strand guide rollers adjacent in the casting direction on the upper frame and / or the lower frame can be reduced in the casting direction. This object is achieved with regard to the arc segment for the subject matter of patent claim 1. Accordingly, the arc segment according to the invention is characterized in that the driven strand guide roller is in the form of a journal roller and at least some, preferably at least 3, more preferably at least 5, more preferably all of the non-driven strand guide rollers are in the form of axle rollers; and that the driven journal rollers have a larger diameter than the non-driven axle rollers.

[0010] Strand guide rollers support the warm cast strand on its broad sides and are typically dimensioned so that they can absorb predetermined bearing or support loads for carrying the cast strand within the strand guide device and so that the necessary adjusting forces can be applied to the cast strand via the strand guide rollers. The adjusting forces must be dimensioned large enough, particularly in the case of driven strand guide rollers, to convey the cast strand within the strand guide device. In addition, the adjusting forces must be dimensioned so that they can counteract the ferrostatic forces of the not yet fully solidified cast strand perpendicular to the surface of the cast strand and thus any bulging of the cast strand. The strand guide rollers must be designed for these and possible other loads, such as liquid core reduction and / or soft reduction.

[0011] The smaller roller diameter, in turn, offers the advantage that the distances between any two adjacent strand guide rollers on the upper frame and / or the lower frame can be reduced in the casting direction. This allows the number of strand guide rollers on the upper and / or lower frame to be increased compared to the exclusive use of pin-type rollers. The required supporting and support loads and positioning forces of an entire segment area can then be distributed across the larger number of strand guide rollers, with the advantage that each individual strand guide roller can be designed for a lower load. The smaller (clear) roller distance and the increased number of strand guide rollers lead to a reduced bulging of the cast strand, i.e.to reduced stretching of the outer and especially the inner fibers (liquid-solid phase boundary) of the still-warm cast strand in the area between two adjacent strand guide rollers. This enables improved surface and internal quality of the cast strand while simultaneously increasing casting speed and thus increasing productivity.

[0012] The object of the invention is further achieved by a strand guide device comprising at least one of the curved segments according to the invention and preferably comprising a cooling device for the strand guide rollers of the curved segment. The advantages of this strand guide device correspond primarily to those mentioned above with reference to the claimed curved segment.

[0013] The invention can be applied in both curved and vertical bending casting systems. Corresponding solutions to the problem are specified in claims 11 and 12.

[0014] Curved casting plants typically have a curved mold to which curved segments adjoin in the casting direction. The strand guide in curved casting plants therefore consists only of curved segments. Vertical bending plants, on the other hand, have a vertically aligned, straight mold to which one or more vertical segments adjoin in the casting direction, before curved segments adjoin the vertical segments. The strand guide in vertical bending plants therefore consists of both vertical segments and curved segments. The present invention relates to the strand guides and the curved segments in curved casting plants and in vertical bending plants. The invention does not relate to the vertical segments mentioned.

[0015] Advantageous embodiments of the arc segment according to the invention and the strand guide according to the invention are the subject of the dependent claims.

[0016] The present invention, the curved segment according to claim 1, applies equally to both undivided and split strand guide rollers. In the latter case, the strand guide rollers of the curved segments are divided into a plurality of sub-rollers over their entire bale length, with support bearings for the upper or lower frame being provided between the sub-rollers. The term "total bale length" includes not only the bale lengths of the sub-rollers but also the width of the support bearings.

[0017] The description is accompanied by three figures, where Fig. 1 a strand guiding device, in particular also with curved segments according to the invention; Fig. 2 a detailed view of the curved segments according to Fig. 1 ; and Fig. 3 shows a comparison of journal rollers and axle rollers.

[0018] The invention will be described in detail below with reference to the figures. Identical technical elements are designated by the same reference numerals in all figures.

[0019] Figure 1 shows a casting plant 100 according to the invention. It can be seen that a melt, in particular a steel melt, is typically first drained from a pouring ladle 110 into an intermediate container 120, typically a so-called tundish, before the melt is poured from the intermediate container into a mold 140 via a dip tube 130. In the mold 140, the initially still liquid melt is primarily cooled, so that a so-called strand shell forms on the walls of the mold. The cast strand 200, partially solidified in this way, with a solid strand shell but still a liquid core, is then withdrawn from the mold 140 and deflected horizontally with the aid of the segmented strand guide 150. Figure 1Using the example of a so-called curved system, it shows that the strand guide in the casting direction G behind the mold 140 initially consists of an arcuate part 150-I and then a horizontal part 150-II. Both parts consist of a plurality of so-called segments arranged one behind the other in the casting direction G to guide the cast strand.

[0020] Each segment consists of an upper frame 162 and a lower frame 164, each of which preferably supports a plurality of strand guide rollers 170 that are rotatably mounted. The upper frame and the lower frame 162, 164 are connected to one another in such a way that their respective strand guide rollers 170 are spaced apart from one another and define a guide channel for the passage of the cast strand 200.

[0021] In the upper section, ie in the casting direction G behind the mold 140, the strand guide 150-I is curved because the strand guide rollers 170 there define a curved guide channel for the cast strand 200. The segments there are therefore also referred to as curved segments 160. Fig. 2 illustrates two such arc segments 160 in detail. Particularly visible is the arc-shaped guide channel spanned by the arc segments 160, whose outer radius r corresponds to the radius of the casting arc. The arc segments 160 have driven and non-driven strand guide rollers 170.

[0022] The arch segments are the subject of the present invention. In the Figure 1 and 2 The white strand guide rollers symbolize that they are not driven, while the strand guide rollers marked with a cross symbolize driven rollers.

[0023] At the strand guide outlet, the rollers of the strand guide segments form a horizontal, straight guide channel. Segments with a straight guide channel are not the subject of the present invention.

[0024] Figure 3 illustrates two different basic types of strand guide rollers, namely so-called pin rollers, as shown in the upper illustration of Fig. 3 shown, and so-called axle rollers, or also called shell rollers, as shown in the lower figure of Fig. 3 As shown in Figure 3 As can be seen, the difference between the two roller types is that with the journal roller, the roller spindle and roller barrel are formed as a single piece, while the axle roller is constructed in multiple parts. With the axle roller, there is typically a fixed, i.e., non-rotating spindle, and a roller shell is rotatably mounted on this rotary spindle via a roller bearing.

[0025] The journal roller is typically used as a drive roller because the drive torque acting on the journal of the journal roller is also directly transmitted to the barrel of the journal roller. The axle roller is typically not used as a driven roller because, as mentioned, its axle is typically clamped in a rotationally fixed manner.

[0026] According to the invention, at least one of the strand guide rollers on the upper frame 162 and / or the lower frame 164 is designed in the form of an axle roller. Regarding the advantages of this invention, reference is made to the above statements in the general part of the description.

[0027] According to the invention, the curved segment 160 has at least one driven and one non-driven strand guide roller 170 on its upper frame 162. The same applies to the associated lower frame 164. For each driven strand guide roller 170, the first exemplary embodiment provides for each to be designed in the form of a journal roller. Of the non-driven strand guide rollers 170, at least some, preferably at least three, more preferably at least five, more preferably all, are designed in the form of axle rollers. Configuring the driven strand guide rollers in the form of journal rollers is still necessary in order to transmit the torque of a drive device via the journal of the roller to the barrel of the journal roller.In the case of non-driven strand guide rollers, there is no need for a rotary drive and therefore, according to the present invention, these are designed in the form of axle rollers in order to be able to exploit the associated advantages described above, in particular the reduced roller spacing a when two strand guide rollers are arranged next to one another in the casting direction.

[0028] The driven journal rollers have a larger diameter than the non-driven axle rollers.

[0029] Furthermore, in order to achieve a low overall height of the strand guide device, it is advantageous if the radius r of the casting arc of the arc segment is less than or equal to 7 m. The casting arc is measured as shown in Figure 2 shown, from the center of the arc of the strand guide to the support surface for the cast strand within the strand guide device formed by the outer sides of the strand guide rollers of the subframe.

[0030] Furthermore, the clear distance d between the outer surfaces of two strand guide rollers 170 on the upper frame 162 and the lower frame 164, which are arranged transversely to the casting direction G as a pair of rollers, is less than or equal to 210 mm.

[0031] Further advantageously, in the arch segment according to the invention, at least 6, preferably at least 7, further preferably at least 8 or further preferably at least 9 strand guide rollers are rotatably mounted on the upper frame and the lower frame.

[0032] Furthermore, it is advantageous that the strand guide rollers of the curved segment according to the invention each have a total barrel length transverse to the casting direction of up to 2,400 mm. This enables the curved segment according to the invention to guide cast strands with widths of up to 2,350 mm, preferably up to 2,200 mm.

[0033] The strand guide device typically has a secondary cooling device for cooling the cast strand. The nozzles of the secondary cooling device are then typically arranged between two strand guide rollers adjacent in the casting direction and aligned such that coolant sprays through the gap between the two adjacent strand guide rollers onto the cast strand guided in the strand guide device. Due to the placement of the secondary cooling nozzles between adjacent strand guide rollers, a minimum clearance a between two strand guide rollers adjacent in the casting direction is required, which is, for example, 40-50 mm. On the fixed side of the curved segment according to the invention, the clearance a is a maximum of 50 mm, preferably a maximum of 45 mm.

[0034] According to an advantageous embodiment of the invention, however, these nozzles of the secondary cooling device can also be used to cool the strand guide rollers from the outside. Therefore, the present invention provides that the nozzles of the strand guide device are designed and aligned to spray coolant not only onto the cast strand, but also onto the strand guide rollers. The strand guide rollers are cooled from the outside in this way. This applies primarily to the non-driven strand guide rollers, which are preferably designed as axle rollers, because these typically, but not necessarily, do not have internal cooling. Likewise, this type of cooling can also be used for the driven strand guide rollers, which according to the invention are typically designed as journal rollers, regardless of whether the journal rollers are cooled internally or not.If necessary, both the internal cooling and the external cooling through the nozzles of the secondary cooling device work together.

[0035] In cases where the strand guide device does not have a secondary cooling device for the cast strand, the secondary cooling device is also not available for cooling the strand guide rollers. In this case, the warm cast strand is cooled via contact with the strand guide rollers and the prevailing ambient temperature. As a result, the (clear) distance a between two adjacent strand guide rollers in the casting direction can theoretically be reduced to a minimum of 0 mm on the fixed and loose sides of the arc segment. This advantageously means a maximum number of strand guide rollers per arc segment. The fixed side of the arc segment is typically formed on the outside of the arc by the lower frames 164, while the loose side on the inside of the arc is formed by the upper frames 162.

[0036] In particular, if no secondary cooling is available, internal cooling is typically required for the driven and / or non-driven strand guide rollers, i.e., regardless of whether they are journal rollers or axle rollers.

[0037] Alternatively or in addition to the internal cooling – and especially if no secondary cooling device is provided – the strand guide rollers can also be cooled by the external cooling device, whose nozzles are then arranged and designed to spray coolant (only) onto the outer sides of the strand guide rollers 170 (and not directly onto the cast strand). This applies regardless of whether the strand guide rollers are driven or not. In the case of internal cooling, the external cooling has an additional effect. Advantageously, if the cooling device is only provided – as described – for external cooling of the strand guide rollers, it can be equipped with a smaller cooling capacity than the secondary cooling device, which is designed for cooling the cast strand. The external cooling only needs to be dimensioned such that it is sufficient to cool the strand guide rollers; it does not have to be designed for cooling the cast strand. List of reference symbols:

[0038] 100Casting system 110Ladle 120Intermediate vessel 130Dip tube 140Mould 150Strand guide device 150-IArc-shaped part of the strand guide 150-IIHorizontal part of the strand guide 160Arc segment 162Upper frame 164Lower frame 170Strand guide rollers 200Casting strand aclear distance between two rollers lying next to each other in the casting direction dclear distance between two rollers lying opposite each other transversely to the casting direction Gcasting direction rRadius of the casting arc

Claims

1. Curved segment (160) in the curved region of a strip guide device (150) for guidance and deflection into the horizontal of a cast strip (200) of metal after leaving a mould (140), comprising a plurality of strip guide rollers (170) which are disposed at a spacing opposite one another and span a curved guide channel for conducting the cast strip (200) onwards; wherein at least one of the strip guide rollers is constructed in the form of an axial roller with a stationary axis; an upper frame (162) at which the plurality of strip guide rollers (170) is rotatably mounted; and a lower frame (164) at which a plurality of strip guide rollers (170) is also rotatably mounted; wherein the upper frame (162) and the lower frame (164) are connected with one another in such a way that their respective oppositely disposed strip guide rollers (170) span the guide channel; wherein the at least one strip guide roller (170) in the form of the axial roller is formed at the upper frame (162) and / or the lower frame (164); and wherein the curved segment (160) has at its upper frame or lower frame (162, 164) at least one respective driven and non-driven strip guide roller (170); characterised in that the driven strip guide roller (170) is constructed in the form of a spigot roller and at least an individual one, preferably at least three, more preferably at least five, even more preferably all, of the non-driven strip guide rollers (170) are constructed in form of axial rollers; and the driven spigot rollers have a greater diameter than the non-driven axial rollers.

2. Curved segment (160) according to claim 1, characterised in that the radius of the casting curve (r) of the curved segment (160) is smaller than or equal to 7 m.

3. Curved segment (160) according to one of the preceding claims, characterised in that the clear spacing (d) between the outer surfaces of two rollers opposite one another transversely to the casting direction (G) as a roller at the upper frame and the lower frame (162, 164) pair is smaller than or equal to 210 mm.

4. Curved segment (16) according to any one of the preceding claims, characterised in that the at least six, preferably at least seven, more preferably at least eight or even more preferably at least nine strip guide rollers (170) are rotatably mounted on the upper frame and the lower frame (162, 164).

5. Curved segment (160) according to any one of the preceding claims, characterised in that the strip guide rollers (170) each have a total circumferential length transverse to the casting direction (G) of up to 2400 mm.

6. Strip guide device (150) for guiding and deflecting a cast strip (200) of metal after leaving a mould (140) into the horizontal, characterised by at least one curved segment (160) according to any one of the preceding claims; and a cooling device for the strip guide rollers (170) of the curved segment (160).

7. Strip guide device (150) according to claim 6, characterised in that a secondary cooling device is provided for cooling the cast strip (200); and the cooling device for the driven and / or non-driven strip guide rollers (170) is constructed in the form of the secondary cooling device, wherein the nozzles of the secondary cooling device are constructed and oriented to spray coolant not only onto the cast strip (200), but also on to the strip guide rollers (170).

8. Strip guide device (150) according to claim 7, characterised in that the clear spacing (a) between two strip guide rollers (170), which are adjacent in casting direction (G), with intermediately arranged nozzle of the secondary cooling device on the fixed side of the curved segment (160) is at most 50 mm, preferably at most 45 mm.

9. Strip guide device (150) according to claim 6, characterised in that no secondary cooling device is provided in the strip guide device (150); and the cooling device is constructed for internal cooling of the driven and / or non-driven strip guide rollers (170).

10. Strip guide device (150) according to claim 8 or 9, characterised in that the clear spacing (a) between two strip guide rollers (170), which are adjacent in casting direction (G), on the fixed side of the curved segment (160) is at most 5 mm, preferably at most 3 mm, more preferably at most 1 mm.

11. Casting plant in the form of a vertical deposit plant for producing a cast strip, comprising: a vertically oriented straight mould; characterised by a strip guide device (150) according to any one of claims 6 to 10 downstream of the mould, wherein at least one vertical segment is arranged between the mould and the at least one curved segment (160) for vertical transfer of the cast strip (200) from the mould to the curved segment.

12. Casting plant in the form of a curved plant for producing a cast strip, comprising: a curved mould; characterised by a strip guide device (150) according to any one of claims 6 to 10 downstream of the mould.

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