Arch segment of a strand-guiding device

Abstract

An arch segment in an arch region of a strand-guiding device guides and deflects a cast strand made of metal into the horizontal after leaving a mold. The arch segment has an upper frame and a lower frame, on each of which a plurality of strand-guiding rollers 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. In order to reduce bulging of the cast strand in the arch region of the strand guide, at least one of the strand-guiding rollers on the upper frame and/or the lower frame is designed in the form of an axle roller.

Description

TECHNICAL FIELD

The disclosure relates to an arch segment in the arch region of a strand-guiding device for guiding and deflecting a cast strand made of metal into the horizontal after leaving a mold. Furthermore, the disclosure also relates to a strand-guiding device with such an arch segment.

BACKGROUND

Strand-guiding devices with arch segments are known in principle in the prior art, for example from the German patent application DE 10 2008 009 136 A1. This patent application teaches that each arch segment has an upper frame and a lower frame, on which in each case a plurality of strand-guiding rollers are rotatably mounted. The upper frame and the lower frame are connected together, in particular adjusted against one another, 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. The individual strand-guiding rollers on the upper frame and the lower frame can be driven in rotation or not.

Furthermore, it is known in the prior art of continuous casting that the cast strand tends to bulge, i.e. deform, after leaving the mold, in particular due to a so-called “ferrostatic pressure” that prevails inside the strand that has not yet solidified, in particular where it is not prevented from doing so in the region of the strand guide, for example by strand-guiding rollers, i.e. in particular in the intermediate spaces between two strand-guiding rollers that are adjacent in the casting direction.

SUMMARY

The present disclosure further develops a known arch segment and a known strand guide with such an arch segment to the effect that bulging of the cast strand in the arch region of the strand guide is reduced.

This is achieved by the arch segment as disclosed and claimed. The arch segment is characterized in that at least one of the strand-guiding rollers on the upper frame and/or the lower frame is designed in the form of an axle roller.

Strand-guiding rollers support the hot cast strand on its wide sides and are typically dimensioned so that they can absorb predetermined load-bearing or supporting loads for carrying the cast strand within the strand-guiding device and so that the required adjusting forces can be applied to the cast strand via the strand-guiding rollers. In particular in the case of driven strand-guiding rollers, the adjusting forces must be dimensioned to be large enough to convey the cast strand within the strand-guiding device. In addition, the adjusting forces must be dimensioned so that they can counteract the ferrostatic forces of the not yet solidified cast strand perpendicular to the surface of the cast strand and thus a bulging of the cast strand. The strand-guiding rollers must be designed in each case for these and other possible loads, such as liquid core reduction and/or soft reduction.

The claimed design of at least one of the strand-guiding rollers as axle rollers with a stationary axle offers the advantage that they can be built with a smaller outer diameter compared to the journal roller with a rotating axle that is common in the prior art for arch segments, with the same load, see last paragraph. The background to this is that the clamping point for the stationary axle with axle rollers can absorb loads better than the bearing point for the rotating axle with journal rollers.

The smaller roller diameter in turn offers the advantage that the spacings between in each case two adjacent strand-guiding rollers in the casting direction on the upper frame and/or the lower frame can be reduced in the casting direction. As a result, the number of strand-guiding rollers on the upper and/or lower frame can be increased compared to the exclusive use of journal rollers. The required load-bearing and supporting loads and adjusting forces of an entire segment region can then be distributed over the larger number of strand-guiding rollers with the advantage that each individual strand-guiding roller can be designed for a lower load. The smaller (clear) roller spacing and the increased number of strand-guiding rollers lead to reduced bulging of the cast strand, i.e. to a reduced elongation of the outer and in particular the inner fibers (phase boundary of liquid-solid) of the still-warm cast strand in the region between two adjacent strand-guiding rollers. This enables an improved surface and internal quality of the cast strand with a higher casting speed and thus higher productivity.

A strand-guiding device includes at least one of the arch segments in accordance with the disclosure and preferably with a cooling device for the strand-guiding rollers of the arch segment. The advantages of this strand-guiding device initially correspond to the advantages mentioned above with reference to the claimed arch segment.

The disclosed arch segments can be used in casting systems in the form of arch systems and vertical bending systems alike.

Arch systems typically have an arch-shaped mold, followed by arch segments in the casting direction. In this respect, the strand guide in arch systems only consists of arch segments. Vertical bending systems, on the other hand, have a vertically aligned straight mold, which is initially followed by one or more vertical segments in the casting direction before the vertical segments are followed by arch segments. In this respect, the strand guide in vertical bending systems consists of both vertical segments and arch segments. The disclosed arch segments apply to the strand guides and the arch segments in arch systems and in vertical bending systems. The disclosed arch segments do not relate to the aforementioned vertical segments.

The present disclosure, and in particular the arch segment, applies equally to both undivided and divided strand-guiding rollers. In the latter case, the strand-guiding rollers of the arch segments are subdivided over their total barrel length into a plurality of partial rollers, wherein support bearings to the upper or lower frame are provided between the partial rollers in each case. The term “total barrel length” includes the width of the support bearings in addition to the barrel lengths of the partial rolls.

BRIEF DESCRIPTION OF THE DRAWINGS

Three figures are attached to the description.

FIG. 1 shows a strand-guiding device with arch segments;

FIG. 2 shows a detailed view of the arch segments in accordance with FIG. 1; and

FIG. 3 shows a comparison of journal rollers and axle rollers.

DETAILED DESCRIPTION

The invention is described in detail below with reference to the figures mentioned. Identical technical elements are designated with the same reference signs in all figures.

FIG. 1 shows a casting system 100. It can be seen that a melt, in particular a steel melt, is typically first drained from a casting ladle 110 into an intermediate container 120, typically a so-called “distribution trough,” before the melt is filled from the intermediate container into a mold 140 via an immersion tube 130. In the mold 140, the initially liquid melt is primarily cooled so that a so-called “strand shell” forms on the walls of the mold. The partially solidified cast strand 200 with a solid strand shell but still liquid core is then pulled out of the mold 140 and deflected horizontally with the aid of the segmented strand guide 150. FIG. 1 shows, using the example of a so-called “arch system,” that the strand guide in the casting direction G behind the mold 140 consists initially of an arch-shaped part 150-I and subsequently of a horizontal part 150-II. Both parts in each case 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.

Each segment consists of an upper frame 162 and a lower frame 164 on which in each case a preferably equal plurality of strand-guiding rollers 170 is rotatably mounted. The upper frame and the lower frame 162, 164 are connected together such that the respective strand-guiding rollers 170 thereof are arranged opposite one another in a mutually spaced manner and define a guide channel for guiding the cast strand 200.

In the upper course, i.e. in the casting direction G behind the mold 140, the strand guide 150-I is arch-shaped, because the strand-guiding rollers 170 provide an arch-shaped guide channel for the cast strand 200. Therefore, the segments there are also referred to as arch segments 160. FIG. 2 illustrates two such arch segments 160 in detail. In particular, the arch-shaped guide channel defined by the arch segments 160, the outer radius r of which corresponds to the radius of the casting arch, can be seen. The arch segments 160 can have driven and/or non-driven strand-guiding rollers 170. The arch segments comprise the subject matter of the present disclosure. In FIGS. 1 and 2, the white strand-guiding rollers symbolize that they are not driven, while the strand-guiding rollers marked with a cross symbolize driven rollers.

In contrast, the rollers of the strand guide segments form a horizontal straight guide channel at the outlet of the strand guide. The segments with a straight guide channel do not comprise the subject matter of the present disclosure.

FIG. 3 illustrates two different basic types of strand-guiding rollers, namely so-called “journal rollers,” as shown in the upper illustration of FIG. 3, and so-called “axle rollers,” also known as shell rollers, as shown in the lower illustration of FIG. 3. As can be seen in FIG. 3, the difference between the two types of roller is that, with the journal roller, the roller axle and the roller barrel are designed in one piece, while the axle roller is designed in several parts. With the axle roller, there is typically a stationary, i.e. non-rotating axle and a roller shell is rotatably mounted on this axis of rotation via a roller bearing.

The journal roller is typically used as a drive roller, because a drive torque applied to the journal of the journal roller is also transmitted directly to the barrel of the journal roller. The axle roller is typically not used as a driven roller because, as already mentioned, its axle is typically clamped so that it cannot rotate.

It is provided that at least one of the strand-guiding rollers is designed on the upper frame 162 and/or the lower frame 164 in the form of an axle roller.

In accordance with a first exemplary embodiment, the arch segment 160 in each case has at least one driven and/or non-driven strand-guiding roller 170 on its upper frame 162. The same applies to the associated lower frame 164. For the respective driven strand-guiding rollers 170, the first exemplary embodiment provides for these to be designed in the form of a journal roller in each case. Of the non-driven strand-guiding rollers 170, at least individual, preferably at least three, further preferably at least five, further preferably all are designed in the form of axle rollers. The design of the driven strand-guiding 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 the non-driven strand-guiding rollers, there is no need for a rotary drive and therefore these are designed in the form of axle rollers, in order to be able to utilize the associated advantages described above, in particular the reduced roller spacing a with two strand-guiding rollers lying next to one another in the casting direction.

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

Furthermore, in view of the low height of the strand-guiding device, it is advantageous if the radius r of the casting arch of the arch segment is less than or equal to 7 m. As shown in FIG. 2, the casting arch is measured from the center of the arch of the strand guide to the support surface formed by the outer sides of the strand-guiding rollers of the lower frame for the cast strand inside the strand-guiding device.

Furthermore, the clear spacing d between the outer surfaces of in each case 2 strand-guiding rollers 170 on the upper frame 162 and the lower frame 164, which are arranged opposite one another as a pair of rollers transverse to the casting direction G, is less than or equal to 210 mm.

Further advantageously, with the arch segment, in each case at least 6, preferably at least 7, further preferably at least 8 or further preferably at least 9 strand-guiding rollers are rotatably mounted on the upper frame and the lower frame.

It is also advantageous that the strand-guiding rollers of the arch segment in each case have a total barrel length transverse to the casting direction of up to 2,400 mm. As a result, the segment is capable of guiding cast strands with widths of up to 2,350 mm, preferably up to 2,200 mm.

The strand-guiding device typically has a secondary cooling device for cooling the cast strand. The nozzles of the secondary cooling device are then typically arranged in each case between two adjacent strand-guiding rollers in the casting direction and aligned such that coolant is sprayed through the gap between the two adjacent strand-guiding rollers onto the cast strand guided in the strand-guiding device. Due to the insertion of the nozzles for secondary cooling between adjacent strand-guiding rollers, a minimum dimension is required for the clear spacing a between two strand-guiding rollers adjacent in the casting direction, which is, for example, 40-50 mm. On the fixed side of the arch segment, the clear spacing a is a maximum of 50 mm, preferably a maximum of 45 mm.

However, in accordance with an advantageous exemplary embodiment, these nozzles of the secondary cooling device can also be used to cool the strand-guiding rollers from the outside. Therefore, the present disclosure provides that the nozzles of the strand-guiding device are designed and aligned to spray coolant not only onto the cast strand, but also onto the strand-guiding rollers. The strand-guiding rollers are cooled from the outside in this manner. This applies primarily to the non-driven strand-guiding rollers, which are preferably designed as axle rollers, because they typically, but not necessarily, have no internal cooling. Similarly, this type of cooling can also be used for the driven strand-guiding rollers 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.

In cases in which the strand-guiding device does not have a secondary cooling device for the cast strand, the secondary cooling device is also not available for cooling the strand-guiding rollers. In this case, the hot cast strand is cooled via the contact with the strand-guiding rollers and the prevailing ambient temperature. As a result, the (clear) spacing a between two adjacent strand-guiding rollers in the casting direction can theoretically be reduced to a minimum of 0 mm on the fixed side and floating side of the arch segment. Advantageously, this means a maximum number of strand-guiding rollers per arch segment. The fixed side of the arch segment is typically formed on the outer side of the arch by the lower frame 164, while the floating side is formed on the inner side of the arch by the upper frame 162.

In particular, if no secondary cooling is available, internal cooling must typically be provided for the driven and/or non-driven strand-guiding rollers, i.e. regardless of whether they are journal rollers or axle rollers.

Alternatively or in addition to the internal cooling—and in particular if no secondary cooling device is provided—the strand-guiding rollers can also be cooled by the external cooling device, the nozzles of which are then arranged and designed such that they spray coolant (only) onto the outer sides of the strand-guiding rollers 170 (and not directly onto the cast strand). This applies regardless of whether the strand-guiding 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 intended for external cooling of the strand-guiding rollers, as described, it can be equipped with a lower cooling capacity than the secondary cooling device, which is designed to cool the cast strand. The external cooling only has to be dimensioned so that it is sufficient to cool the strand-guiding rollers; it does not have to be designed to cool the cast strand.

LIST OF REFERENCE SIGNS

• • 100 Casting system
  • 110 Casting ladle
  • 120 Intermediate container
  • 130 Immersion tube
  • 140 Mold
  • 150 Strand-guiding device
  • 150-I Arch-shaped part of the strand guide
  • 150-II Horizontal part of the strand guide
  • 160 Arch segment
  • 162 Upper frame
  • 164 Lower frame
  • 170 Strand-guiding rollers
  • 200 Cast strand
  • a Clear spacing between two rollers lying next to one another in the casting direction
  • d Clear spacing between two rollers arranged opposite one another transverse to the casting direction
  • G Casting direction
  • r Radius of the casting arch

Claims

1.-15. (canceled)

16. An arch segment (160) in an arch region of a strand-guiding device (150) for guiding and deflecting a cast strand (200) made of metal into a horizontal orientation after leaving a mold (140), comprising: a plurality of strand-guiding rollers (170) which are arranged opposite one another in a mutually spaced manner and define an arch-shaped guide channel for guiding the cast strand (200);an upper frame (162) on which upper ones of the plurality of strand-guiding rollers (170) are rotatably mounted; anda lower frame (164) on which lower ones of the plurality of strand-guiding rollers (170) are rotatably mounted,wherein the upper frame (162) and the lower frame (164) are connected together such that their respective oppositely arranged strand-guiding rollers (170) define the arch-shaped guide channel,wherein at least one of the upper ones of the plurality of strand-guiding rollers (170) and at least one of the lower ones of the plurality of strand-guiding rollers (170) is a driven strand-guiding roller (170),wherein the driven strand-guiding roller (170) is a driven journal roller,wherein some of the upper ones of the plurality of strand-guiding rollers (170) and some of the lower ones of the plurality of strand-guiding rollers (170) are non-driven strand-guiding rollers (170),wherein at least some of the non-driven strand-guiding rollers (170) are non-driven axle rollers with a fixed axle, andwherein the driven journal rollers have a larger diameter than the non-driven axle rollers.

17. The arch segment (160) according to claim 16, wherein a radius of a casting arch (r) of the arch segment (160) is less than or equal to 7 m.

18. The arch segment (160) according to claim 16, wherein a clear spacing (d) between outer surfaces of one of the upper ones of the plurality of strand-guiding rollers (170) and one of the lower ones of the plurality of strand-guiding rollers (170), which are arranged opposite one another as a pair of rollers transverse to a casting direction (G), is less than or equal to 210 mm.

19. The arch segment (160) according to claim 16, wherein at least six of the strand-guiding rollers (170) are rotatably mounted on each the upper frame (162) and the lower frame (164).

20. The arch segment (160) according to claim 16, wherein the strand-guiding rollers (170) have a total barrel length transverse to a casting direction (G) of up to 2400 mm.

21. A strand-guiding device (150) for guiding and deflecting a cast strand (200) made of metal into a horizontal orientation after leaving a mold (140), comprising: the arch segment (160) according to claim 16; anda cooling device for the strand-guiding rollers (170) of the arch segment (160).

22. The strand-guiding device (150) according to claim 21, further comprising: a secondary cooling device for cooling the cast strand (200),wherein nozzles of the secondary cooling device are designed and aligned to spray coolant not only onto the cast strand (200), but also onto the strand-guiding rollers (170).

23. The strand-guiding device (150) according to claim 22, wherein a clear spacing (a) between two strand-guiding rollers (170) adjacent in a casting direction (G) with at least one of the nozzles of the secondary cooling device arranged between them on a fixed side of the arch segment (160) is a maximum of 50 mm.

24. The strand-guiding device (150) according to claim 21, wherein no secondary cooling device is provided in the strand-guiding device (150); andwherein the cooling device is designed for internal cooling of the driven strand-guiding roller (170) and/or the non-driven strand-guiding rollers (170).

25. The strand-guiding device (150) according to claim 23, wherein a clear spacing (a) between two strand-guiding rollers (170) adjacent in the casting direction (G) on a fixed side of the arch segment (160) is a maximum of 5 mm.

26. A casting system in form of a vertical bending plant for producing a cast strand, comprising: a vertically aligned straight mold; andthe strand-guiding device (150) accordance with claim 21 arranged downstream of the mold in,wherein at least one vertical segment is arranged between the mold and the arch segment (160) for vertically transferring the cast strand (200) from the mold into the arch segment.

27. A casting system in form of an arch system for producing a cast strand, comprising: a curved mold; andthe strand-guiding device (150) in accordance with claim 20 arranged downstream of the mold.