Arch segment of a strand-guiding 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] Curved segment of a strand guide device

[0002] The invention relates to a curved segment in the curved region of a strand guide device for guiding and deflecting a cast metal strand into the horizontal position after it leaves a mold. Furthermore, the invention also relates to a strand guide device with such a curved segment.

[0003] 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 support, on each of which a plurality of strand guide rollers are rotatably mounted. The upper frame and support 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 support can be rotationally driven or not.

[0004] 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.

[0005] The invention is based on the object of further 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.

[0006] This object is achieved with respect to the arc segment for the subject matter of patent claim 1. Accordingly, the arc segment according to the invention is characterized in that at least one of the strand guide rollers on the upper frame and / or the lower frame is designed in the form of an axle roller.

[0007] 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.

[0008] The claimed design of at least one of the strand guide rollers as axle rollers with a fixed axis offers the advantage that they can be built with a smaller outer diameter compared to the journal rollers with a rotating axis that are customary in the prior art for arch segments, see last paragraph, for the same load. The background to this is that the clamping point for the fixed axis in axle rollers can absorb loads better than the bearing point for the rotating axis in journal rollers. 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 makes it possible to increase the number of strand guide rollers on the upper and / or lower frame compared to using journal rollers exclusively.The required load-bearing 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 spacing and the increased number of strand guide rollers lead to reduced bulging of the cast strand, i.e., to reduced stretching of the outer and, in particular, 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.

[0009] 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.

[0010] The invention can be applied in both curved and vertical bending casting systems. Corresponding solutions to the problem are specified in claims 14 and 15.

[0011] 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.

[0012] 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.

[0013] The present invention, and in particular 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.

[0014] The description is accompanied by three figures, where

[0015] Fig. 1 shows a strand guiding device, in particular also with curved segments according to the invention;

[0016] Fig. 2 shows a detailed view of the arch segments according to Fig. 1; and Fig. 3 shows a comparison of the journal rollers and axle rollers. 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.

[0017] Figure 1 shows a casting system 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 1 shows, using the example of a so-called curved system, that the strand guide in the casting direction G behind the mold 140 initially consists of an arc-shaped part 150-1 and then of a horizontal part 150-11.Both parts consist of a plurality of so-called segments arranged one behind the other in the casting direction G in order to guide the cast strand.

[0018] Each segment consists of an upper frame 162 and a lower frame 164, each of which preferably supports an equal number of strand guide rollers 170. The upper frame and the lower frames 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 span a guide channel for the passage of the cast strand 200.

[0019] In the upper section, i.e. in the casting direction G behind the mold 140, the strand guide 150-1 is curved because the strand guide rollers 170 define a curved guide channel for the cast strand 200 there. The segments there are therefore also referred to as curved segments 160. Fig. 2 illustrates two such curved segments 160 in detail. In particular, the curved guide channel spanned by the curved segments 160 can be seen, the outer radius r of which corresponds to the radius of the casting arc. The curved segments 160 can have driven and / or non-driven strand guide rollers 170. The curved segments are the subject of the present invention. In Figures 1 and 2, the white strand guide rollers symbolize that they are not driven, while the strand guide rollers marked by a cross symbolize driven rollers.

[0020] 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.

[0021] Figure 3 illustrates two different basic types of strand guide rollers, namely so-called journal rollers, as shown in the upper illustration of Fig. 3, and so-called axle rollers, or also called shell rollers, as shown in the lower illustration of Fig. 3. As can be seen in Figure 3, the difference between the two roller types is that with the journal roller, the roller axis and the roller body are formed as a single piece, whereas the axle roller is formed from several parts. With the axle roller, there is typically a fixed, i.e. non-rotating axis, and a roller shell is rotatably mounted on this axis of rotation via a roller bearing.

[0022] 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.

[0023] According to the invention, at least one of the strand guide rollers on the upper frame 162 and / or the support 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.

[0024] According to a first exemplary embodiment, the curved segment 160 has at least one driven and / or non-driven strand guide roller 170 on its upper frame 162. The same applies to the associated lower frame 164. For the respectively driven strand guide rollers 170, the first exemplary embodiment provides for these 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. The design of 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.

[0025] The driven journal rollers can have a larger diameter than the non-driven axle rollers.

[0026] Furthermore, with regard to 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, 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 lower frame. Furthermore, the clear distance d between the outer surfaces of each of two strand guide rollers 170 on the upper frame 162 and the support frame 164, which are arranged transversely to the casting direction G as a pair of rollers, is less than or equal to 210 mm.

[0027] 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 undercarriage.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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 strand guide rollers adjacent in the casting direction can theoretically be reduced to a minimum of 0 mm on the fixed and loose sides of the arch segment. This advantageously means a maximum number of strand guide rollers per arch segment. The fixed side of the arch segment is typically formed on the outside of the arch by the supports 164, while the loose side on the inside of the arch is formed by the upper frames 162.

[0032] Particularly when no secondary cooling is present, internal cooling is typically provided for the driven and / or non-driven strand guide rollers, i.e., regardless of whether they are journal rollers or axle rollers. Alternatively or in addition to internal cooling—and particularly when no secondary cooling device is provided—the strand guide rollers can also be cooled by the external cooling device, the nozzles of which are then arranged and designed to spray coolant (only) onto the outer surfaces 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, external cooling has an additional effect.Advantageously, if the cooling device is intended solely for external cooling of the strand guide rollers, as described, it can be equipped with a lower cooling capacity than the secondary cooling device, which is designed for cooling the cast strand. The external cooling system only needs to be dimensioned to be sufficient to cool the strand guide rollers; it does not need to be designed for cooling the cast strand.

[0033] List of reference symbols:

[0034] 100 casting plant

[0035] 1 10 ladle

[0036] 120 intermediate containers

[0037] 130 dip tube

[0038] 140 mold

[0039] 150 strand guide device

[0040] 150-1 curved part of the strand guide

[0041] 150-11 horizontal part of the strand guide

[0042] 160 arch segment

[0043] 162 upper frame

[0044] 164 subframes

[0045] 170 strand guide rollers

[0046] 200 Cast strand a Clear distance between two rolls lying next to each other in the casting direction d Clear distance between two rolls lying opposite each other transversely to the casting direction

[0047] Roll

[0048] G Pouring direction r Radius of the pouring arc

Claims

Patent claims:

1. Arc segment (160) in the arc region of a strand guiding device (150) for guiding and diverting a cast metal strand (200) after it leaves a mold (140) into the horizontal position, comprising: an upper frame (162) on which a plurality of strand guide rollers (170) are rotatably mounted; and a support (164) on which a plurality of strand guide rollers (170) are also rotatably mounted; wherein the upper frame (162) and the support (164) are connected to each other in such a way that their respective strand guide rollers (170) are spaced apart from each other and form an arc-shaped guide channel for guiding the cast strand (200); characterized in that at least one of the strand guide rollers (170) on the upper frame (162) and / or the support (164) is designed in the form of an axle roller.

2. Bow segment (160) according to claim 1, characterized in that the bow segment (160) has at least one driven and / or non-driven strand guide roller (170) on its upper or lower section (162, 164); and that the driven strand guide roller (170) is in the form of a pin roller and at least some, preferably at least 3, further preferably at least 5, further preferably all of the non-driven strand guide rollers (170) are in the form of axle rollers.

3. Arc segment (160) according to claim 2, characterized in that that the driven pivot rollers have a larger diameter than the non-driven axle rollers. Arc segment (160) according to one of the preceding claims, characterized in that the radius of the casting arc (r) of the arc segment (160) is less than or equal to 7 m. Arc segment (160) according to one of the preceding claims, characterized in that the clear distance (d) between the outer surfaces of two rollers arranged opposite each other as a roller pair transversely to the casting direction (G) on the upper and lower frames (162, 164) is less than or equal to 210 mm. Arc segment (160) according to one of the preceding claims, characterized in that at least 6, preferably at least 7, more preferably at least 8, or more preferably at least 9 strand guide rollers (170) are rotatably mounted on the upper and lower frames (162, 164).Arc segment (160) according to one of the preceding claims, characterized in that the strand guide rollers (170) each have a total coil length transverse to the casting direction (G) of up to 2400 mm. Strand guide device (150) for guiding and deflecting a cast metal strand (200) into the horizontal position after it has left a mold (140). characterized by at least one arc segment (160) according to one of the preceding claims; and preferably a cooling device for the strand guide rollers (170) of the arc segment (160). Strand guide device (150) according to claim 8, characterized in that a secondary cooling device is provided for cooling the cast strand (200); and that the cooling device for the driven and / or non-driven strand guide rollers (170) is designed in the form of the secondary cooling device, wherein the nozzles of the secondary cooling device are designed and oriented to spray coolant not only onto the cast strand (200) but also onto the strand guide rollers (170).Strand guiding device (150) according to claim 9, characterized in that the clear distance (a) between two strand guiding rollers (170) adjacent in the casting direction (G) with the nozzle of the secondary cooling device arranged between them on the fixed side of the arc segment (160) is a maximum of 50 mm, preferably a maximum of 45 mm. Strand guiding device (150) according to claim 8, characterized in that no secondary cooling device is provided in the strand guiding device (150); and that the cooling device is for internal cooling of the driven and / or. The strand guide device (150) according to claim 8 or 11 is characterized in that no secondary cooling device is provided in the strand guide device (150); and that the cooling device for the driven and / or non-driven strand guide rollers (170) has nozzles for spraying the strand guide rollers (170) with a coolant; and that the cooling device is designed for a cooling capacity sufficient to cool the strand guide rollers (150), but not the casting strand (200). The strand guide device (150) according to claim 11 or 12 is characterized in that the clear distance (a) between two strand guide rollers (170) adjacent in the casting direction (G) on the fixed side of the arc segment (160) is a maximum of 5 mm, preferably a maximum of 3 mm, and more preferably a maximum of 1 mm.A casting system in the form of a vertical bending system for producing a casting strand, comprising: a vertically oriented straight mold; characterized by a strand guiding device (150) downstream of the mold according to one of claims 8 to 13, wherein at least one vertical segment is arranged between the mold and the at least one arc segment (160) for vertically transferring the casting strand (200) from the mold into the arc segment. Casting system in the form of an arc system for producing a casting strand, comprising: a curved mold; characterized by a strand guiding device (150) downstream of the mold according to one of claims 8 to 13.

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