EP2257397B1 - Strand guide segment - Google Patents

Abstract

In a strand guide segment for supporting and guiding a cast metal strand  in a strand guide of a continuous casting plant comprising strand guide rollers attached to cross beams, it is intended to continuously ensure a convex cross-sectional shape of the cast strand under varying load conditions of the cast strand. This is accomplished with a plate-like cross beam (7) comprising a longitudinal slot (20) that runs parallel to the longitudinal extension of the strand guide roller (5a).

Description

The invention relates to a strand guide segment for supporting and guiding a cast metal strand in a strand guide of a continuous casting with a plurality of strand guide rollers which are supported in a segment frame of the strand guide segment on cross members, wherein at least one of the cross member is plate-shaped. In particular, the invention relates to a strand guide segment for supporting and guiding a cast steel strand.

In a continuous casting in the strand guide between the mold and the horizontally arranged outlet roller table for the strand - with the cross-sectional format of a slab, a thin slab or a strip - strand guide rollers arranged individually or in strand guide segments. In addition, adjustable and drivable strand guide rollers are provided at intervals from one another on the cast strand and at the start of casting on the starter strand. By the contact forces applied by these strand guide rollers, the controlled transport of the cast strand or the Anfahrstranges is ensured by the continuous casting at a predetermined conveying speed.

A strand guide segment of the type described above is from the WO 01/94051 A1 already known. It comprises two rows of strand guide rollers supported on cross beams, the cross beams being arranged in successive segment frames. In addition, a strand guide rollers supporting cross member is guided on vertical guides in the segment frame movable and can be made to the cast strand or the Anfahrstrang. The necessary contact force is applied by a clamping device designed as a pressure cylinder, which acts centrally on the cross member. The central contact force causes a deflection of the arc inside cross member and the strand guide rollers supported thereon.

A desired convex (crowned) cross-sectional shape of the cast strand is achieved when the outer arch portion and the inner arch portion of a segment are braced by acting on the four segment corners clamping cylinders. A similar deformation pattern is achieved in a cross member with employed strand guide rollers when two adjusting devices engage in each case in the end regions of the cross member thereto. Such an embodiment is known from WO 2006/037555 A1 already known. However, this embodiment has the disadvantage that two synchronously operating pressure medium cylinder must be provided.

From the WO 02/13994 A1 It is known to provide an approximately lying on the strand central axis force member in the region of a soft reduction path for determining the sump tip on the fixed side of the segment frame. As a result, due to the self-adjusting bending line of the rollers, the profile superelevation can be reduced by counterbending the segment cross member.

To set a symmetrical curvature of the roller gap, it is out of EP 941 787 A1 known to assign the guide roller pair pressure and position controlled adjustment, said adjustment act directly on the center bearings of the strand guide rollers.

In order to counteract or to influence the springing up of a segmental frame as a result of the ferrostatic pressure of the liquid core region of the cast strand, FIGS WO 2008/022731 A1 different ways known. These consist either in a crowning of the interposed strand guide rollers or in a resilient design of the outer bearing in relation to the intermediate bearings or in an inclined position of the strand guide rollers. Ultimately, all of these options are structurally complex and considerably increase the costs of spare parts management in the wear parts, especially the strand guide rollers and roller bearings.

The object of the present invention is to avoid the disadvantages of the known prior art and to propose a strand guide segment with at least one strand guide rollers supporting cross member of the type described above, in which always a convex in cross-section of the cast strand (convex) cross-sectional shape is ensured.

This object is achieved on the basis of a strand guide segment of the type described above in that at least one cross member has a longitudinal slot aligned parallel to the longitudinal extent of the strand guide rollers.

A particularly advantageous embodiment is that at least one cross member supporting a strand guide roller is slidably formed in the segment frame normal to the direction of longitudinal extension of the strand guide roller, this displaceable cross member is connected via at least one Anstellinrichtung with the segment frame and the displaceable cross member is plate-shaped and a parallel to Has longitudinal extension of the strand guide roller aligned longitudinal slot. This ensures a convex cross-sectional shape in the cross-section of the cast strand even with a largely central arrangement of a setting device, as occurs in the case of the strand guide rolls not employed with a central setting device. Furthermore, the investment costs for the segments and the necessary piping costs are kept low.

In the case of the unhardened strand guide rollers, the segment tension of the four tensioning cylinders arranged on the segment corners results in a convex deformation of the stationary cross members and thus in a desired biconvex shape of the cast strand. When engageable cross member of the same design would result from the centric introduction of the adjusting force a counter-concave deformation of the cross member and thus the driven strand guide rollers. The resulting within a segment different deformation of the strand shells could lead to problems with the slab quality. The arrangement of the longitudinal slot in an area between the articulation point of the Anstelleinrichtung and the strand guide roller, there is a deflection of the contact force and thus also to a convex deformation of the cross member and the desired biconvex cross-sectional shape of the cast strand.

Suitably, the longitudinal slot in the cross member between a pivot joint for the articulation of the adjusting device on the cross member and the strand guide roller is arranged.

To achieve optimum deformation of the displaceable cross member, which corresponds to the contact line of the strand guide rollers with the cast strand of the stationarily arranged in the frame frame cross member, the longitudinal slot in the cross member has a slot length which is less than one of the coaxial and arranged on this cross member supported strand guide roller formed support length. As a support length of the strand guide roller here is the distance between the two outer side faces of the arranged on the movable cross member strand guide roller to understand.

According to a preferred embodiment, the longitudinal slot in the cross member has a slot length which is less than one of the coaxially arranged and supported on this cross member strand guide roller and reduced by half the length of the edge strand guide roller sections support length.

A cross member is always assigned a "strand guide role". This strand-guiding roller comprises a plurality of strand guide roller sections, which each extend between adjacent bearing points in the case of a multi-layered roller. For the purpose of this definition, a plurality of rollers mounted on a crossbeam and aligned axially independently also fall under the term "strand guide roller".

Suitably, the longitudinal slot extends in the cross member between two aligned normal to the longitudinal extent of the strand guide roller guides.

To ensure a sufficient deflection of the contact force in the two edge regions of the displaceable cross member, it is necessary that the longitudinal slot in the cross member has a slot length which is greater than one third of the coaxially arranged and supported on this cross member strand guide roller support length.

Advantageously, the connecting device connecting the cross member to the segment frame has an effective line of force application which divides the slot length of the longitudinal slot in the cross member and the support length formed by the strand guide roller in the middle. Thus, a symmetrical to the center line bending line is achieved. Since the longitudinal slot in the cross member has expansion areas at its ends, edge cracking in this area is certainly avoided. These end-side expansion areas are circular. The diameter of the circular extension regions is equal to or greater than the slot width of the longitudinal slot. The circular widening region thus comprises end sections of the longitudinal slot which terminate in semicircular fillets or circular widenings which terminate the longitudinal slot. The extension areas may also differ slightly from the circular shape. They allow a voltage optimization in the sense of avoiding voltage spikes regardless of the slot width and surface finish of the slot.

Fig. 1

eine axonometrische Darstellung eines Strangführungssegmentes mit einem anstellbaren und Strangführungsrollen tragenden Querträger,

Fig. 2

den im Innenbogensegmentrahmen angeordneten verlagerbaren Querträger in einem Teilschnitt der Figur 1,

Fig. 3

eine Frontalansicht des erfindungsgemäßen Querträgers,

Fig. 4a bis 4c,

eine vergleichende Darstellung der Auswirkungen der Spannkräfte und Anstellkräfte im Segment auf die Querschnittsform des gegossenen Stranges.

Further advantages and features of the present invention will become apparent from the following description of a non-limiting embodiment, reference being made to the attached figures, which show:

Fig. 1

an axonometric representation of a strand guide segment with an engageable and strand guide rollers bearing cross member,

Fig. 2

arranged in the inner arc segment frame displaceable cross member in a partial section of FIG. 1 .

Fig. 3

a frontal view of the cross member according to the invention,

4a to 4c,

a comparative presentation of the effects of the clamping forces and contact forces in the segment on the cross-sectional shape of the cast strand.

In a continuous casting plant for the production of steel strands in the slab format, a cast strand with still liquid core and a thin strand shell is continuously formed in an oscillating cooled continuous casting mold. In one of the continuous casting mold in the casting direction downstream strand guide with several meters radius of curvature of the casting strand is deflected under constant cooling of substantially vertical direction in the horizontal and directed straight there. A plurality of strand guide rollers, which are arranged in two rows, form a transport channel for the cast strand, in which it is supported and guided. Some of the strand guide rollers are designed as driver rollers and provided with a motor drive to ensure a controlled conveying speed for the casting strand and at the start of casting for the starter strand. In Casting successive strand guide rollers of both rows are summarized in assemblies in a strand guide segment. Such a continuous casting plant is for example from the EP 908 256 A1 known.

The strand guide is composed of individual strand guide segments, such as one in Fig. 1 is shown schematically in axonometric representation. Each strand guide segment comprises a segment frame 1 which is formed by an outer arc segment frame 2 a and an inner arc segment frame 2 b, which are interconnected by four hydraulically actuable bracing devices 3 a, 3 b, 3 c, 3 d arranged in the corner regions of the segment frame 1, which have a predetermined positioning of Allow inner arch segment frame 2b to the outer arch segment frame 2a. Thus, the bearing housings 6 mounted on successively arranged cross members 4 strand guide rollers 5 can be adjusted to the degree of strand thickness or casting start on the thickness of the Anfahrstranges. Each strand guide roller 5 is formed as a continuous, multi-bearing roller or a plurality of aligned rollers. The cross members 4 are fixedly secured in the inner bow segment frame 2 b or in the outer bow segment frame 2 a.

Fig. 2 shows in a partial section of Fig. 1 a arranged in the inner arc segment frame 2b sliding cross member 7, which carries a plurality of bearing housing 6 which receive a multi-bearing, coupled to a drive 9a strand guide roller 5a rotatably. A similar, driven strand guide roller 5b is disposed in the outer arch segment frame 2a opposite and in Fig. 1 indicated by the drive 9b, which is opposite to the drive 9a. The driven strand guide roller 5b is supported in stationary cross beams 4 in the same way as the adjacent strand guide rollers 5 fastened in the outer arc segment frame 2a (FIG. Fig. 1 ). The provided for the driven strand guide roller 5a sliding roller carrier 7 is on the one hand via a pivot joint 11 connected to a controllable pressure medium cylinder Anstelleinrichtung 10, on the other hand via a pivot joint 12 on the inner arc segment frame 2b is supported. The two pivot joints 11, 12 define a connecting line 13, which corresponds to the line of action of the application of force to the cast strand and in FIG. 2 coincides with the central axis of the adjusting device 10.

Parallel to the connecting lines 13, guides 15a, 16a are fastened on both sides to the displaceable cross member 7, which cooperate with corresponding counter guides 15b, 16b on the inner bow segment frame 2b. The guides 15a are arranged on the broad sides of the cross member 7, approximately at a distance of a half strand guide roller section 5c, 5e from its side edges. The guides 16a bear against the end faces of the cross member 7. The guides 15a and counter guides 15b stabilize the cross member 7 in the casting direction G, the guides 16 and counter guides 16b in the transverse direction thereto. The cross member 7 has a longitudinal slot 20 which is parallel to the axis of rotation 14 of the driven strand guide roller 5a and extends between the two vertical guides 15a. The adjusting forces introduced with the adjusting device 10 in the cross member are redirected through the longitudinal slot and change the voltage conditions in the cross member.

FIG. 3 shows the movable or engageable on the cast strand cross member 7 with the mounted thereon bearing housings 6 and the rotatably supported strand guide roller 5a, which is formed in several parts and three strand guide roller sections 5c, 5d, 5e. The movable cross member 7 is plate-shaped and carries a series of previously described vertical guides 15a, 16a. Between the mounted in the upper edge region and the middle of the cross member 7 pivot joint 11 and the strand guide roller 5a of the cross member 7 is penetrated by a longitudinal slot 20 with a slot length L _Sch . The slot length is shorter than the support length L _St , which is determined by the edge-side end faces of the strand guide roller sections 5c, 5e. In the concrete embodiment of the FIG. 3 the slot length L _{Sch is} also less than the support length L _St formed by the strand guide roller 5a and reduced by half the length of the edge-side strand guide roller sections 5c, 5e. The slot length L _Sch is also longer than one third of the support length L _St formed by the coaxially arranged strand guide roller. It extends in an area between the two vertical guides 15a. The longitudinal slot 20 in the cross member 7 is at its two ends in circular extension areas 21, 21 a over. The diameter of these circular extension regions 21, 21 a is at least twice as large as the slot width B _Sch . In FIG. 3 two embodiments of the extension region 21, 21 a are shown. The extension portion 21 has a diameter larger than that Slot width B _Sch . The extension portion 21 a has a diameter corresponding to the slot width B _Sch .

In the FIG. 3 illustrated embodiment of an engageable on the cast strand cross member is analogous even with a non-adjustable cross member, which is fixed rigidly in an outer arch segment frame or inner arch segment frame applicable.

A comparative illustration of the effects of the clamping forces and contact forces in a strand guide segment on the cross-sectional shape of the cast strand is in the Figures 4a, 4b and 4c illustrated and illustrates the advantage of the inventive solution.

FIG. 4a illustrates an inner arc segment frame 2b, which is braced with the outer arch segment frame, not shown, via four arranged in the corner region bracing devices 3a, 3b, 3c, 3d. The tension forces F _Sp applied by the tensioning devices are transmitted via the cross members 4 fixedly arranged in the segment frame to the strand guide rollers 5 and thus to the cast strand 30. This leads to a deflection of the cross member and the strand guide rollers, as in the lower picture of the FIG. 4a and results in a biconvex deformation of the cast strand 30. This is a desired shape per se, which ensures centered strand transport in the continuous casting plant.

For the special case of a displaceable in the segment frame guided and engageable with a central contact force F _A against the cast strand cross member 7, which is formed according to the prior art without a longitudinal slot, sets a deformation image, as shown in FIG. 4b is shown schematically. The central contact force leads to a deflection of the adjustable cross member 7 and supported on it strand guide rollers 5a. This deflection is transmitted to the cast strand and therefore leads inside the bow to a concave deformation of the cast strand 30 and may increase the bow outer side convex strand deformation. These occurring in the region of the inner arc segment frame 2b at a distance of two roller pitch deformation changes from convex to concave and then again from concave convex can lead to crack formation, especially in the case of deformation-sensitive steel grades.

In Figure 4c In contrast, an engageable against the cast strand 30 cross member 7 is loaded with the longitudinal slot 20 according to the invention with a central contact force F _A. Since a power transmission via the longitudinal slot 20 is not possible, there is a deflection of the load to the edge regions of the cross member 7 and thus to the end regions of the strand guide roller 5a. The cast strand 30 is therefore much more heavily loaded in its lateral edge zones than in its central area. This also leads to a biconvex deformation image, as is analogous to the rigidly positioned cross members 4 in FIG. 4a established. The harmful changing deformation therefore no longer occurs in the inventive design of a strand guide segment.

The invention is not limited to the embodiment described in detail. Rather, the longitudinal slot according to the invention can be arranged on any strand guide rollers carrying cross members both on the outer bow and on the inner bow of the strand guide. This possibility exists regardless of whether this cross member is rigidly anchored in a strand guide segment, as inner arc segment part is adjustable or designed as an individual component in the strand guide segment with a cross member associated Anstelleinrichtung adjustable.

Likewise, the strand guide segment can also comprise only one cross member carrying at least one strand guide roller.

Claims (10)

1. Strand guide segment for supporting and guiding a cast metal strand in a strand guide of a continuous casting installation, comprising a multiplicity of strand guide rollers (5, 5a, 5b) supported on cross beams (4, 7) in a segment frame (1) of the strand guide segment, at least one of the cross beams (7) having a plate-shaped design, characterized in that at least one cross beam (7) has a longitudinal slot (20) which is oriented parallel to the longitudinal extent of the strand guide roller (5a).
2. Strand guide segment according to Claim 1, characterized in that at least one cross beam (7), which bears a strand guide roller (5a), is designed so as to be displaceable normally to the direction of the longitudinal extent of the strand guide roller (5a) in the segment frame (1), said displaceable cross beam (7) is connected to the segment frame (1) via at least one setting device (10), and the displaceable cross beam (7) has a plate-shaped design and has a longitudinal slot (20) which is oriented parallel to the longitudinal extent of the strand guide roller (5a).
3. Strand guide segment according to Claim 2, characterized in that the longitudinal slot (20) is arranged in the cross beam (7) between a pivot joint (11), which is intended to couple the setting device (10) to the cross beam (7), and the strand guide roller (5a).
4. Strand guide segment according to one of the preceding claims, characterized in that the slot length (L_Sch) of the longitudinal slot (20) in the cross beam (7) is less than a support length (L_St) which is formed by the coaxially arranged strand guide roller (5a) supported on said cross beam (7).
5. Strand guide segment according to one of Claims 1 to 3, characterized in that the slot length (L_Sch) of the longitudinal slot (20) in the cross beam (7) is less than a support length (L_St), which is formed by the coaxially arranged strand guide roller (5a) supported on said cross beam (7) and is reduced by half the length of the edge-side strand guide roller portions (5c, 5e).
6. Strand guide segment according to one of Claims 1 to 3, characterized in that the longitudinal slot (20) extends in the cross beam (7) between two guides (15a) oriented normally to the longitudinal extent of the strand guide roller (5a).
7. Strand guide segment according to one of the preceding claims, characterized in that the slot length (L_Sch) of the longitudinal slot (20) in the cross beam (7) is greater than one third of the support length (L_St) which is formed by the coaxially arranged strand guide roller (5a) supported on said cross beam (7).
8. Strand guide segment according to one of Claims 2 to 7, characterized in that the setting device (10) connecting the cross beam (7) to the segment frame (1) has a line of action for the application of force, which divides the slot length (L_Sch) of the longitudinal slot (20) in the cross beam (7) and the support length (L_St) formed by the strand guide roller (5a) in the center.
9. Strand guide segment according to one of the preceding claims, characterized in that the ends of the longitudinal slot (20) in the cross beam (7) are provided with widened regions (21, 21a).
10. Strand guide segment according to Claim 9, characterized in that the end-side widened regions (21, 21a) have a circular design and the diameter of the circular widened regions (21, 21a) is equal to or greater than the slot width (B_Sch) of the longitudinal slot (20).

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