JP2004505775A - Method for supporting, guiding and cooling of cast strands made of steel, in particular of coarse members for girders, and a strand guiding mechanism - Google Patents

Abstract

A method and strand guide for supporting, guiding and cooling casting strands (1) made of steel, especially preliminary sections (2) for girders, which are cooled by injected water (29) and are drawn. The inventive method prevents cracks, especially surface cracks, from appearing in the microstructure by adapting the cooling conditions of the surface of the strand during secondary cooling. Undercooling of the chill of the strand is prevented by adapting the cooling and support of the beam blank format to the solidification range in order to avoid an undesirable solidification structure on the upper flange edges or in other cross-sectional areas so that cooling and support are provided exclusively where a crater is formed. The casting strand (1) is cooled by guiding the temperature in a specific manner in upper supporting segments (5, 6, 7) by means of injected water jets whose width at least matches the length of the supporting rollers on longitudinal and transversal sides (13, 14) of the cross section (1a) of the casting strand, and is decreasingly supported in an analogous manner with respect to the length of the casting path and the cooling state in core areas (15) of the cross section (1a) of the casting strand on the transversal sides (14) of said casting strand cross section (1a) and cooling occurs exclusively by means of water jets (8) which are oriented towards said core areas (15).

Description

[0001]
The present invention relates to a method for supporting, guiding and cooling a cast strand of steel, in particular a BBL-girder blank, and a strand guide mechanism, in which the cast strand leaves the continuous casting mold. Later, in the zero segment, in the secondary cooling device, and in the subsequent support segment, it is subsequently cooled and withdrawn by spray water.
[0002]
From Japanese Patent Application Laid-Open No. 4-200844, in the strand guide mechanism for the long side of the casting section, individual support rolls are partially provided as chip rolls and partially provided in the profile web portion. It is known for use as long rolls of length. On the wide side of the casting cross section, a support roll of an appropriate length is provided in that case. This arrangement, however, does not take into account any strand shell thickness and cooling equipment required at the casting strand location concerned.
[0003]
The function of the strand guide mechanism is not only to provide the support of the cast strand against the static pressure of the molten steel, but also to maintain the profile geometry formed in the continuous casting mold and to solidify by the secondary cooling device Providing also with heat removal should be taken into account. However, surface cracks still occur.
[0004]
The purpose of the strand guiding mechanism must be a defect-free surface quality of the cast strand, a crack-free and segregation-free inner quality, with high profile fidelity.
[0005]
The problem underlying the present invention is therefore the adaptation of the cooling conditions of the strand surface in the region of the secondary cooling device, by which cracks in the tissue structure, in particular surface cooling cracks, and in this secondary cooling device, In particular, supercooling of the strand skin is to be avoided.
[0006]
In accordance with the invention, the object of the invention is to provide cooling and cooling of beam blank moldings in order to avoid undesired solidification structures at the flange upper edge or in other cross-sectional areas in a method according to the preamble of claim 1. The support is solved by adapting the solidification zone so that the support is cooled and supported only in the area where the pool formation is located near that area.
[0007]
In one embodiment of the method, the casting strand is
By means of a suitable temperature guidance, in the upper support segment, at least with the width of the spray water jet corresponding to the length of the support roll, along the longitudinal and transverse sides of the section of the cast strand. Cooled,
And corresponding to the strand path length and the cooling state in the core region of the cast strand cross section, supported on the lateral side of the cast strand cross section so as to taper,
And it is cooled with only a spray water jet having the same or smaller pool side width oriented to the slightly liquid core area. As a result, supercooling of the strand skin is avoided and the risk of cracks, especially surface cracks, is significantly reduced.
[0008]
In a further embodiment of the present invention, the cast strand is:
With suitable temperature guidance, it is supported in the zero support segment along the profile end of the cast strand and in the longitudinal lateral center region of the transverse section of the cast strand and along the lateral sides. And, at that time, the longitudinal side surface and the lateral side surface of these cast strand cross sections are cooled except for the cast strand shape corner region,
And only a central region of the cast strand cross-section and both lateral sides are supported in the progressive strand crust formation on the strand path length; and
In the area of the sump tip of the core area, the lateral sides are limitedly supported and cooled in the area of the sump tip or plurality of sump tips, and along the longitudinal side a slight amount of hot water It is proposed that a spray water jet directed only to the sump area be used. In this way, a suitable temperature guidance is achieved not only in the rectangular cast strand section, but also in the profile strand, depending on the cross-sectional area of the cast strand section.
[0009]
A further feature of the invention is that, in the region of the basin section, the cast strand section is supported without spray water cooling along the lateral sides of the cast strand section. Advantageously, the flow of heat from the hotter zone into the already cooled zone takes place without significant temperature jumps.
[0010]
Suitable temperature guidance is furthermore provided in that the cast strands are guided on a support roll with sufficient solidification, without spray water jets and without support from the top and sides. It is completed as it is.
[0011]
The object is furthermore to provide, according to the invention, by means of guiding and cooling, that the cast strands can be provided with suitable temperature guidance in the individual support segments, in which case the strand shape can be changed from support segment to support segment. The use of a secondary cooling device adapted to the material, and
The support segment which is continuous with the zero support segment is solved by being formed open so that excess spray water can be derived from the cast strand cross section in a number of directions. This makes it possible, via a secondary cooling device adapted to the process, of strand corners (flange corners) having ductility properties which are degraded by a suitable support segment configuration with an optimal arrangement of the strand guide rolls. The tendency for supercooling is avoided, and thus the occurrence of cracks is avoided in the tissue structure and at the surface. In this case, a relatively uniform temperature distribution is likewise achieved in the cross section of the cast strand.
[0012]
With the temperature-guided cooling and support in the manner according to the invention, the following effects are obtained:
-Minimal water injection, just to derive the heat of solidification,
-Reduction of running water (Lauffasser) for supercooling of the upper flange surface and other cross-sectional areas;
A uniform temperature pattern in the BBL section,
Temperature guidance from the mold to the correction work area,
Control of the surface temperature in the advantageous ductility region,
The effect of is achieved.
[0013]
The strand guide segments should be adapted in construction to process engineering requirements. Therefore, this configuration is in the following manner:
Support rolls, which only support in the basin area,
-A segment configuration in which the upper side of the flange is not covered,
-Ensuring optimal water runoff characteristics;
-Water catch plates and guide plates on the upper surface of the segment, so that the running water is generated as little as possible;
In the form of
[0014]
According to a further feature, the support and secondary cooling device is provided in the zero support segment by means of a relatively long pair of support rolls in which the longitudinal sides of the section of the casting strand are arranged symmetrically in the middle. The angular section of the strand profile is supported by a relatively short pair of tip rolls, and the lateral sides of the cast strand cross section are supported by a pair of support rolls of a length corresponding approximately to the side length. It is formed as it is. This type of support is advantageous, for example, for strand skin thicknesses between 30 and 50 mm. This support takes place practically from all sides only in the well profile, in order to avoid undesired undercooling.
[0015]
In other embodiments, only a relatively long pair of support rolls, arranged symmetrically in the middle slightly along the longitudinal sides of the cast strand cross section, and on the lateral sides, in the subsequent support segments Along therewith, a pair of support rolls corresponding to approximately the side length is arranged. Here, the strand skin thickness is already assumed between 40 and 60 mm, so that the corner areas of this cast strand cross-section no longer need to be supported.
[0016]
A further reduction of the supporting force is achieved in such a way that, in other supporting segments, the pair of support rolls, which are arranged symmetrically along the lateral sides, are shortened in each case by other features. . This is based on the fact that the central region of the cast strand is now completely solidified, and that the strand shell has a thickness in the outer region of up to about 50 to 70 mm. And
[0017]
In the subsequent solidification, only a shortened pair of support rolls, arranged symmetrically along the lateral sides, are provided in the subsequent support segment. In the case of rough cast strands, the present invention envisages in the corner region of the cross section of the cast strand a strand skin thickness of already from 70 to 90 mm.
[0018]
In doing so, it is proposed that the casting strand rests on the support roll only along the lower surface, within the part of sufficient core solidification.
[0019]
The improvement is such that the spray pattern of the secondary cooling device is widened corresponding to the core area of the pouring basin. In this way, an excessively high water load is avoided.
[0020]
Here, the excess spray water can advantageously be discharged. As a result, only a minimal amount of water strikes the strand support at the center of the cast strand, for example on the profile edge of the coarse section.
[0021]
In a further embodiment, a long support roll is associated with just as wide or a wider spray water jet. This configuration can be used especially for relatively thin strand skins, up to about 30 to 60 mm.
[0022]
In essence, in embodiments, the tip rolls are located only in the support segments that follow the zero support segment.
[0023]
The drawings show an embodiment of the invention, which will now be described in detail.
[0024]
As an example, a cast strand 1 for a blank 2-from which a girder is rolled-is shown (FIGS. 1 and 1A). After leaving the continuous casting mold 3, this casting strand 1 is cooled by a secondary cooling device in the zero support segment 4 and in subsequent support segments 5, 6 and 7 by a spray water jet 8, and It is pulled out by the driven roll of the drawing device 9.
[0025]
At every 2 m, the strand skin thickness is described with a thickness indication in mm. The length L indicates the total equipment length from the continuous casting mold 3 to the drawing device 9. Furthermore, the radii R1, R2 and R3 define the arc of the strand course.
[0026]
The casting strand 1 is exposed to a spray water jet 8 having a width 10 which is equal to or greater than the length 11 of the support roll pair 12 in the (upper) zero support segment 4 with suitable temperature guidance. A spray water jet 8 such as these is used along the longitudinal side 13 and the lateral side 14 of the cast strand cross section 1a (FIGS. 2A-2H). Corresponding to the strand path length and the cooling conditions in the core section 15 which still has a viscous liquid melt in the cast strand cross section 1a, these lateral sides 14 are supported in a tapering manner ( 2D-2F) and these spray water jets 8 are directed only to the core area 15 (FIG. 2D).
[0027]
In accordance with the best possible method (FIGS. 2A to 2H), the cast strand 1 formed in the continuous casting mold 3 in a shape-reliable manner enters the zero-support segment 4 (FIG. 2B), In the segment, this cast strand 1 is provided along a longitudinal side 13 by a support roll 17 arranged in a central region 16 of the longitudinal side and by a support roll 18 arranged along a lateral side 14. Supported. At this time, the cast strand shape corner region 19 is not cooled and is supported by the tip roll 20. The spray water jets 8 each form an open angle in the direction of flow with respect to the strands which are still present in the liquid or viscous liquid region, and the strand width or strand thickness of this strand. . As a result, heat is removed to a relatively high degree only where there is still a liquid or viscous liquid melt inside the casting strand 1, while, on the other hand, the already solidified areas, the basic The remaining strand outer skin 21 remains in a state where heat is not removed. This results in a relatively slow cooling of the strand corners and thus little or no surface cracking. According to FIG. 2c, the spray water jet 8 is still maintained in a wide fan-shaped spread. In FIG. 2D, it can be immediately recognized that only the central region 16 of the cast strand cross section 1a is supported by the support roll 17 and is no longer cooled. These spray water jets 8 are directed only to the core area 15. The support roll 18 is held relatively short. This expedient temperature guidance continues in the course of the strand travel (FIG. 2E) to such an extent that only a small spray water jet 8 is directed along the longitudinal side 13 to the core area 15. In short, this core area 15 (FIG. 2F) is very small, so that the casting strand 1 no longer needs to be cooled at all and is guided along the lateral side 14 by only a few support rolls 18. Is done. In FIG. 2G, the core area 15 is further reduced and the casting strand 1 is guided only on a slightly horizontal support roll 22. According to FIG. 2H, this cast strand 1 is completely solidified. The thickness of the strand shell 21 is, for example, 38.2 mm in FIG. 2B, 54.0 mm in FIG. 2C, and 66.1 mm in FIG. 2E, a state of 76.4 mm in FIG. 2F, a state of 93.5 mm in FIG. 2G, and a state of 101.0 mm in FIG. 2H.
[0028]
In FIG. 3, one of the support segments 5, 6, 7 is shown. Accordingly, the structural components are basically one upper frame 23, one lower frame 24, one side frame 25, a dismantling roll 26, and a spray bar 27, respectively.
[0029]
4A and 4B show the outflow of the respective spray water 29 directed in the arrow direction 28. This outflow is possible in particular by means of the “open” shape of the support segments 5, 6, 7 in which the cast strand cross section 1a has, on the basis of the open frame, respectively, outer ribs 30, reinforcements 31, It is surrounded on four sides by an inner rib 32 and a respective nozzle base 33.
[0030]
The illustration in FIG. 4A here corresponds approximately to the strand path length in FIGS. 2B and 2C. The illustration in FIG. 4B corresponds approximately to the strand path length of FIG. 2D.
[0031]
FIG. 5 shows a vertical sectional view of the support segments 5, 6, 7 shown in the actuated state, the open configuration of the support segments 5, 6, 7 being particularly easily recognizable. . The spray water 29 oriented toward the casting strand cross section 1 a by the spray water jet 8 from the nozzle stand 33 can easily flow around between the reinforcing portions 31 and flow out.
[0032]
FIG. 6 shows the appearance of the supporting roll stands 5, 6, 7 in the configuration described with respect to FIG.
[Brief description of the drawings]
FIG.
FIG. 3 is a view of the cast strand in a side view, together with the strand skin thickness belonging to the cast strand path, for the raw material cast strand.
FIG. 1A
It is a figure of the cast strand cross section in a continuous casting mold.
FIG. 2A
It is a figure of the casting strand cross section in the exit of a continuous casting mold.
FIG. 2B
It is a figure of the cast strand cross section which showed both the support roll apparatus and the secondary cooling apparatus in a zero segment.
FIG. 2C
FIG. 7 is a cross-sectional view of a cast strand showing both the support roll device and the secondary cooling device in the support segment that follows.
FIG. 2D
FIG. 4 is a cross-sectional view of a cast strand showing both a support roll device and a secondary cooling device in a further support segment.
FIG. 2E
FIG. 5 is a cross-sectional view of a cast strand in which a support roll device and a secondary cooling device are both shown in the next support segment.
FIG. 2F
FIG. 4 is a cross-sectional view of a strand before completely solidifying without a secondary cooling device.
FIG. 2G
It is a figure of the strand cross section at the time of solidification almost completely.
FIG. 2H
FIG. 4 is a cross-sectional view of a strand after completely solidified and placed on a roller table.
FIG. 3
FIG. 4 is a perspective view of a support segment.
FIG. 4A
FIG. 3 is a perspective sectional view of a support segment, which also shows a tip roll.
FIG. 4B
FIG. 4 is a perspective sectional view of a support segment without a tip roll.
FIG. 5
FIG. 3 is a schematic side view in cross section of a zero support segment in an open configuration.
FIG. 6
FIG. 3 is a schematic view of a zero support segment in an open configuration.
[Explanation of symbols]
DESCRIPTION OF REFERENCE NUMERALS 1 Casting strand 1a Casting strand cross section 2 Coarse material (Strand material)
Reference Signs List 3 continuous casting mold 4 zero support segment 5 support segment 6 support segment 7 support segment 8 spray water jet 9 drawing device 10 width (of spray water jet)
11 Length 12 Support roll pair 13 Longitudinal side (of cast strand)
14. Lateral side (of cast strand)
Reference Signs List 15 Core area 16 Central area 17 of longitudinal side face Support roll 18 Support roll 19 Cast strand shape corner area 20 Tip roll 21 Strand skin 22 Horizontal support roll 23 Upper frame 24 Lower frame 25 Side frame 26 Demolition roll 27 Spray bar 28 Arrow direction 29 Spray water 30 Outer rib 31 Reinforcement part 32 Inner rib 33 Nozzle base

Claims (15)

A method for supporting, guiding and cooling a cast strand of steel, in particular a girder blank, in which the cast strand is left in a zero segment after leaving the continuous casting mold. In the above method in a manner of being cooled and withdrawn in a subsequent cooling device and in a subsequent support segment, subsequently by spray water,
In order to avoid undesired solidification structures at the flange upper edge or in other cross-sectional areas, the cooling and supporting of the beam blank compact is only carried out in the vicinity of the area and in the area where the reservoir formation is present. A method characterized in that it is adapted to a solidification zone so as to be cooled and supported. The cast strand is
With suitable temperature guidance, in the upper support segment, at least with the width of the spray water jet corresponding to the length of the support roll, cooling along the longitudinal and transverse sides of the cast strand cross section,
And corresponding to the strand path length and the cooling state in the core region of the cast strand cross section, supported on the lateral side of the cast strand cross section so as to taper,
The method according to claim 1, characterized in that the cooling is effected with only a spray water jet having the same or a smaller pool side width, oriented with respect to the slightly liquid core area. The cast strand is
With suitable temperature guidance, it is supported in the zero support segment, along the profile ends and in the longitudinal lateral center region of the transverse section of the cast strand, and along the transverse sides of the cast strand. And the longitudinal and lateral sides of the cast strand are cooled except for the profile corner regions;
Only a central region of the cast strand cross-section and both lateral sides are supported in the strand crust formation progressive on the strand path; and
In the region of the sump tip in the core area, the lateral sides are limitedly supported and cooled in the area of the sump tip, and along the longitudinal sides only a little to the sump area. 3. The method according to claim 1, wherein a directed spray water jet is used. 4. The casting strand cross section is supported in the region of the basin section along the lateral sides of the casting strand cross section and subsequently without spray water cooling. The method described in. 2. The casting strand according to claim 1, wherein the casting strand is guided on a support roll in a sufficiently solidified state, without spray water jets and without support from above and from the side. The method according to any one of claims 1 to 4. A strand guide mechanism for a cast strand made of steel, in particular, for a raw material for a girder,
A secondary cooling device having a continuous casting mold followed by a zero support segment, and a spray water jet, and said strand guide mechanism comprising a continuous, subsequent support segment, and a drawing machine;
The cast strands (1) can provide suitable temperature guidance in the individual support segments (4, 5, 6, 7), from the support segments (4) to the support segments (7). The availability of a secondary cooling device adapted to the solidification state of the profile (2); and
The support segments (5, 6, 7) that are continuous with the zero support segment (4) open so that excess spray water (29) can be derived from the cast strand cross section (1a) in multiple directions (28). A strand guide mechanism characterized by being formed. In the zero support segment (4), the longitudinal sides (13) of the cast strand cross section (1a) are arranged symmetrically in the middle by a relatively long pair of support rolls (17) and by the cast strand. The profile corner area (19) is supported by a tip roll pair (20); and
7. The method according to claim 6, wherein the lateral sides of the cast strand cross section are supported by a pair of support rolls of a length corresponding to approximately the side length. The strand guide mechanism according to 1. In the following supporting segments (5, 6, 7), only a relatively long pair of supporting rolls (17) arranged slightly in the middle along the longitudinal side (13) of the cast strand section (1a) 8. Strand according to claim 6, characterized in that a pair of support rolls (18) corresponding to approximately the side length are arranged along the lateral sides (14) of the cast strand cross section. Guide mechanism. In each of the following support segments (5, 6, 7), a pair of support rolls (18) arranged along the lateral sides (14) are each configured to be shortened. The strand guide mechanism according to any one of claims 6 to 8, wherein 7. The support roll according to claim 6, wherein only a symmetrically shortened pair of support rolls (18) is provided along the lateral sides (14) in the subsequent support segments (5, 6, 7). 10. The strand guide mechanism according to any one of items 1 to 9. The casting strand (1) is characterized in that it is configured to rest on the support roll (22) only along the lower surface of the casting strand within a portion of sufficient core solidification. The strand guide mechanism according to any one of claims 6 to 10. Strand according to any one of claims 6 to 11, characterized in that the spray pattern of the secondary cooling device is configured to be widened corresponding to the casting basin core area (15). Guide mechanism. 13. Strand guide mechanism according to any one of claims 6 to 12, characterized in that the excess spray water (29) is arranged to be able to be drawn off. 14. The spray water jet (8), which is just as wide or wider, is assigned to the long support roll (17; 18). Strand guide mechanism. Strand guide according to one of the claims 6 to 14, characterized in that the tip roll (20) is arranged only in the support segment (5) following the zero support segment (4). mechanism.