DE1957758A1 - Method and device for strand cooling in curved continuous casting plants for metals, in particular steel - Google Patents

Description

60NTIHUA International Continuous Casting srl. ,
in Ferrara (Italy).

"Process and device for strand cooling in
Curved continuous casting plants for metals, in particular
dere of steel ".

The invention relates to a method for strand cooling in curved continuous casting plants of metals, in particular of
Steel, in which the casting space cast in a continuous mold with vertika learning straight casting space, emerge from this with all around solidified band crust and molten core de cast strand below the mold, preferably by means
Splash water is nachgekiüilt and initially passes through a straight, vertical, coaxially arranged guide to the mold and then inevitably bent to the side on a subsequent, curved guide

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You curved strand guide section can be a circular arc Show course, with the cast strand practically only through a one-time in the transition area between the ver vertical straight guideway and the subsequent ge_ bent Pührungsabschnitt bending moment acting is inevitably bent. On the other hand, the curved strand guide section also a progressively increasing curvature, e.g. a parabolic, hyperbolic or similar ver have run, the cast strand when passing through this Pührungsstrecke by correspondingly continuously acting bends, moment is inevitably bent.

With the well-known continuous casting process in curved continuous casting plants will be the strand in each considered The strand cross-section below the continuous mold is equally strong on the outside of the curve and on the inside of the curve Strand side cooled, so that the solidified strip crusts of the cast strand in each strand cross-section below the Ko Kill practically the same thickness on both the outer and inner curvature sides of the strand point.

On the other hand, the above is used in all Krummätranggiessahlagen described type in the area of the inevitable bending of the cast strand which lies / The edge crust on tension and that on the inside of the curvature η The edge crust on the strand side is subjected to pressure. During the compressive stress of the inner curvature edge crust generally does not cause any difficulties, the train can

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stress on the crust of the crust, in particular with some types of steel to the formation of bites in the transition zone (dendritic zone) between the molten material Strand core and the solidified crust of the tape, even in this one solidified tape crust itself lead if the tension caused by the tensile stresses are too great for the strength properties of the strand material.

The object of the invention is to eliminate these disadvantages and to develop a method for strand cooling in curved continuous casting plants of metals, in particular steel, with which the described harmful influence of the inevitable strand bending practically eliminates, ie the formation of bites in the tensile outer curvature Part of the strand cross-section is avoided or at least reduced to a level that is insignificant for the quality of the cast strands .

According to the invention, this object is achieved in that, before the inevitable strand bend is applied, ie at least in the area of the vertical straight strand guide section, each strand cross-section on the curvilinear outer strand side is so intensely treated than on the curvilinear strand side that a curvature outer strip crust is greater than that the inside of the curvature band crust forms.

With the strand cooling process according to the invention below the continuous mold, at least in the area of the vertical straight strand guide section, i.e. before the start the inevitable bending of a strand of glass

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cold, whose outer curvature band crust is a larger one Exhibits thickness ^ than the inner crust of the curvature. As a result· This greater thickness of the outer crust of the curvature becomes the Nullir when the casting strand is inevitably bent ■ Never the tension-pressure distribution in the strand cross-section adjusted against the curvature outer strand side. As a result, the » maximum -specific elongations of the tensile stressed material fiber in the outer curvature part of the strand cross-section and consequently the cracks in the solidified one caused by these elongations. outer curvature "band crust or /. in the dendritic zone between this solidified crust of the sand and the melted liquid Strand core avoided.

The inventive device for performing the above Strand cooling process in Krumm-Stranggiessanlageη the The type described at the outset is characterized in that at least in the area of the vertical straight strand guide section the water spray dCisen on the curvature outer ' Strand side in larger numbers and / or with smaller mutual Are arranged at a distance and / or have a greater spray performance than all of the barrel spray nozzles other strand sides especially on the inside of the curve Strand side.

Further features, gate parts and details of the inventive The method and the device proposed for carrying out this method result from the following -..-: End of the description of a preferred, in the drawing schematically illustrated embodiment. Show it;

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Pig. 1 - a Krumm continuous caster for steel ^ in verticals Cut.

Pig. 2, 3 and 4 - cross-sections through the G-iesstrang according to the lines H-II ₁ IH-III and IV-IV of Pig. 1, on a larger scale.

Pig. 5 - a cross section through one according to a conventional one Process cooled cast strand. In the area the section line II-II of the Pig. 1.

Pig. 6 - a cross section through a cast strand cooled by the method according to the invention _> in the region of the section line II-II of the Pig. 1.

The one in Pig. 1 schematically shown curved continuous casting plant for steel "consists of a water-cooled continuous mold 2 with a straight vertical casting space and a strand guide 3, '4 arranged below the mold 2. The strand guide consists of an immediately below the mold 2 arranged, to this coaxial, vertical, straight Pührungsabschnitt 3 and a subsequent, curved, circular arc-shaped guiding lines 4. Both strand guiding lines 3 and 4 are made of rotatably mounted support rollers 5 formed, which in the area of the vertical straight Pührungsabschnitt 3 all around the strand S around, however in the area of the adjoining circular arc-shaped guide section 4, at least on the outer curvature and the Curvature inner strand side E and A are arranged. Between the backup rollers 5 are in both strand guide sections 3, 4 inwardly directed towards the strand S, arranged around this on all sides. Water spray nozzles 6, 106, 206 provided *;

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.- ■■ - * - 195775B

pie vertical, straight strand guide section 3 can be a loading. have any height H. However, preferably corresponds to the height H of this vertical straight strand guide streoke 3 about 1 to 2 times the Y / ert of the mold height H1. the Circular arc-shaped strand guide 4 can be any. Corresponding to the central angle C, which is at most approximately equal to 90 °.

The molten steel is poured from a casting or distribution vessel 7 into the continuous mold 2. In the mold 2, a solidified steel layer 8, which represents the so-called edge crust of the cast strand S, forms on the cooled mold walls on all sides. This solidified edge crust 8 initially lies against the inner mold walls, ie in the upper section L1 of the mold 2, and slides downwards thereon, its thickness increasing progressively. In the lower portion L2 of the mold 2, where the strength of the solidified peripheral crust 8 withstand the ferr © static pressure of the molten strand core 9 or _above: can overcome, the edge crust 8 triggers due to shrinkage on all sides on the mold wall. The cast strand S emerging from the lower opening of the continuous mold 2 thus consists of a peripheral crust 8 solidified all around and a molten core 9

'After exiting the mold 2 of the cast strand S, the clear Durehgangaöffnung for Giesstrang between the Stlitzwalsen 5 SSER g £ raden Pührungsstrecke 3 formed _s first passes through the vertical straight guide path 3 while being aftercooled on all sides by the associated spray nozzles 6, 106, S corresponds within the scope of the tolerances

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the actual strand cross-section at the outlet end of the continuous mold 2. In one embodiment, the grit space of the continuous mold 2 has a square cross-section with a side length of 101% . (+ 0.4 ·? - 0.0) to · Here, a strand shrinkage of 1.3 $ "to 1.5 $ of the length of the side of the mold casting space is assumed through hole for the Giesstrang is consequently a side length of 99 _t 5 mm. adjusted.

In the transition area between the vertical straight line Guide route 3 and the subsequent arc-shaped Guide path 4 ·, i.e. «approximately in the area of the cutting line IX-II of FIG. 1, the strand S is bent once, with the bending moment due to the last sets of support rollers in the guide section 3 and the first sets of support rollers of the guide line 4- is applied. The now bent glass strand S the circular arc-shaped guide path 4, whereby it continues through the associated water spray nozzles 6, 206 until complete solidification, i. E. After-cooled until the molten strand core 9 disappears will. The average water cooling of the cast strand S im, based on the unit of the strand surface The range of the straight guide route 3 is about 3 to 7 times, preferably about 4 to 6 times stronger than the corresponding cooling in the area of the circular arc-shaped guide path 4. As a result, the thickness of the tape crust 8 increases in a straight line Guide part so strongly that the cast strand S undergoes the mechanical bend when it enters the circular arc-shaped guide section 4 can withstand harmless *

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In the known Krumm continuous casting plants of this type the cast strand S1 in any strand cross-section below the mold 2 with the same intensity on the curvature outer strand side E and on the curvature inner Strand side A cooled. The solidified edge crust 8 of a cast strand obtained with this known cooling method As a result, especially in the end section of the ver_ vertical straight guiding section 3 both on the outside of the curvature strand side E and on the inside of the curvature Strand side A practically the same thickness as in the diagram -. · Table in Pig. 5 is shown. In the area of inevitable Bend of this cast strand S1 between the vertical straight Pührungsabschnitt 3 and the adjoining circular arc Pührungss track 4 runs the zero line N1-N1, the the outer curvature pull area from the inner curvature pressure area separates, approximately in the middle of the strand cross-section, d. H. at the same distance "h" from the curvature outer Strand side E and the inside curvature strand side A. Among these Under certain circumstances, when the strand is bent, the tensile stresses in the curvature-free area of the strand cross-section resulting elongations ^ especially with some types of steel. reach such a large value that they cause undesired or harmful bites in the transition zone D (dendritic zone) between the molten strand core 9 and the solidified curvature outer strip crust 80, even in cause this curvature-sweet band crust 80 itself.

According to the invention, in the area of the vertical, straight guide line 3, each strand cross-section is now cut on the outer curvature Strand side E cooled significantly more intensively than on the other strand sides and in particular than on the

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inner curvature strand side A, in such a way that, a curvature outer band crust 108 forms, the one much greater strength than the ligament crusts on the others Strand sides and in particular as' the inner curvature Ranäkruate 208, as shown in Pig «2 and β is. In the area of the inevitable bending of this cast strand S between the vertical straight guide section 3 and the subsequent circular arc fjarmigert guide route 4 runs as a result, the zero line N-N, which separates the outer curvature tension area from the inner curvature pressure area of the The strand cross-section separates, externally through the strand cross-section. This zero line N-N is equal to that obtained with the known cooling process on the Aussereη curvature and on the inner curvature side of the strand cooled cast strands S1 according to FIG from Fig. 6 is shown. The distance "hl" of the NuI line N-N from the curvature outer strand side B is therefore significantly smaller ^ than the distance "h.2" of the zero line N-N from the inside of the curve of the strand A.

The maximum specific elongations or compressions of the material fibers when the inevitable bending of the Cast strands S are directly proportional to the distance "h1" the zero line N-N from the tensile stressed outer curvature side E or to the distance "h2" of the zero line N-N from the inside curvature side A. As a result, the maximum specific elongations in the solidified, tensile part of the outer curvature of the strand cross-section in relation to the one with the herk & emlichen Process of cooled cast strands S1 according to Pig. 5 accordingly

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the smaller distance "h1" from the zero line N-N so far reduced that in the solidified curvature exterior Edge crust 108 and in the transition zone D (dendrite zone) between this marginal crust 108 and the molten one • The strand core 9 can practically not form any cracks, or the_ In terms of quality, there is no further justifiable hatred be reduced. At the same time, the stresses and the resulting maximum specific deformations in the solidified, pressure-loaded inner curvature area of the strand cross-section in relation to the cast strands S1 according to Pig cooled with the conventional methods. 5 corresponding to the greater distance "h2" from the zero line N-N increased, but these greater pressure loads or compressions can be removed from the cast strand S without damage are absorbed and in any case do not cause any cracks in the inner curvature edge crust 208 or in the dendritic zone between this marginal crust 208 and the schmelzflussigeη Strand core 9. Incidentally, ground the inside curvature side of the strand A and the two lateral strand surfaces are preferably equally cooled in such a way that the inner edge crust on the inside of the curvature 208 and the two lateral marginal crusts of the casting strand S are approximately the same thickness as the corresponding marginal crusts of the cast strands S1 obtained by the conventional method, as can be seen from a comparison of Pig. 5 and β can be seen is.

In connection with the unequal cooling according to the invention of the outer curvature and the inner curvature side of the strand B or A in the area of the vertical, straight guide strut. are the arrangement of this guide line 3 and the perfect Kihrung of the cast strand S in the area

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the same especially important. The straight lead 3 namely serves not only to support the majority cast strand consisting of molten steel, but rather also prevents the automatic bending of the cast strand S as a result of the different degrees of cooling of the outer curvature and the strand side E or A. Deformations in the solidified strip crust 8 of the cast strand S avoided, but there are any disturbances at the same time the dendrite formation in the transition zone between the solidified band crust 8 and the molten strand core 9 excluded. As a result, the strength of the solidified strip crust 8 of the cast strand S when passing through the straight Increase strand guide section 3 undisturbed and quickly until the necessary for the subsequent turning of the Cast strand S desired strength ratio between the thicker curvilinear band crust 108 and thinner inner curvature band crust 208 is reached.

The stronger cooling of the curvature-outer strand side E in the area of the straight guiding section 3 can practically be achieved with any structural means or measures. For example, a larger number of more densely arranged spray nozzles 106 can be provided on the curvature outer strand side E than on any other strand side, as is shown in particular in FIG. It is also possible to arrange the same number of spray nozzles on all sides of the strand and to use spray nozzles 106 of greater spraying power on the strand side E on the outside of the curvature. The .Erhöhung the krümmungsäusseren ^r strand cooling towards the.

/ ■ "" ■■■ '■': ■ " ^: ' :

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BATH ORIGINAL

Cooling of the other sides of the strand and in particular of the inner curvature of the strand cooling depends on the dimensions and shape of the cast strand cross-section, as well as on the steel properties and the maximum permissible elongations in the tensile part of the strand cross-section. For example, the cooling of the strand side E with no curvature can be about $ 20 to $ 100 more, a-ls the cooling of every other strand side or the strand side A with the inner curvature.

After the cast strand S has turned from the vertical straight guide section 3 into the subsequent circular arc-shaped guide section 4, the difference between the greater cooling intensity of the outer curvature side E and the lower cooling intensity of the other strand sides, in particular the inner curvature side A, can be abrupt or in The strand longitudinal direction is progressively reduced or abandoned, even reversed, in such a way that the solidified edge crusts on all strand sides, in particular the edge crusts 108, 208 on the outer and inner curvature sides E and A, respectively, assume the same thickness before the strand cross-section is complete has solidified · For this purpose, the greater cooling intensity of the outer curvature, strand side E can be reduced and / or the lower cooling intensity of the other strand sides, especially the inner curvature side A, can be increased strand S eccentric, that is, in the direction of the outer curvature side E of the strand cross-section, the drain line NN moves towards the inner curvature strand side A and is in the center of the strand

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cross-section a »The still molten one, im. The bending area of the eccentric strand core 9 is accordingly centered, and the strand cross-section again assumes a symmetrical shape before the cast strand S has completely solidified, as in particular in Pig. 4 is shown. Pig. 3 shows the strand cross-section in a transition phase between FIGS. 2 and 4. It can also be seen from Figures 3 and 4; 6 is on every other strand side, that is to say that in the illustrated embodiment the uniformity of the strip crust thickness of all strand sides following the strand bending area is achieved by reducing the originally increased cooling intensity on the strand side E on the outside of the curvature. In connection with this equalization of the strip crust thickness, the circular arc-shaped: guide section 4 serves not only to support the cast strand S, but also to hold the bent strand on the advanced circular arc-shaped path, against the effects of the different cooling of the jet sides or caused by the different increases in thickness of the marginal crusts. Warping tendencies of the cast strand.

The invention can be applied can dip gene in such writhing Stranggiessanla- in which follows the vertical straight guide path 3 a curved guide track that no kreisbog'enförmigen course, but a progressively increasing, for example, parabolic, hyperbolic or has ahnlicheKrÜmmung, wherein the glass strand at the Passing through this guiding route continuously according to compulsory

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is bent over the course of time. In this case, it may be sufficient to cool the outer curvature side B of the strand more intensely than the other strand sides, in particular than the inner curvature side A, only in the area of the vertical, straight guide section 3. The glass strand S running from the vertical, straight guide section 3 into the subsequent curved guide section has a band crust 108 on the outside of the curvature of greater thickness than the band crust on the other strand sides, in particular on the inside of the curvature strand side A, but progresses during the subsequent one increasing bending of the cast strand S in the curved guide section, the zero line NN between the tension and pressure areas of the strand cross-section maintains its eccentric position unchanged at the end of the straight guide section, ie does not move against the curvature. outer strand side E, as required by the increase in strand bending. On the other hand, in the case of strand guide sections with a progressively increasing curvature, the more intensive cooling of the outer curvature side E of the strand side E, which begins in the area of the vertical, straight guide section 3, can also be continued in the area of the subsequent ^ curved guide section and can be increased progressively in the longitudinal direction of the strand in accordance with the increasing strand bend. As a result; which increases the strength difference between the krümmungsäusseren and SeM curvature inner Eandkruste 108 or '208 of Giesstrangs S in the region of the curved strand _f to progressively guide path. The zero line NN between the tension and pressure areas of the strand cross-section therefore moves progressively towards the strand side E on the outside of the curvature in accordance with the increase in strand bending in the curved flow path. In both cases, in the lower range

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the curved strand guide section or at a suitable distance before the complete solidification of the cast strand the difference in intensity between the more intensive curvature outer strand cooling and the weaker cooling the other sides of the strand in order to even out the thickness of the hand crust all sides of the strand are abruptly or gradually reduced, abolished or even reversed.

The invention is of course not limited to that shown Embodiment limited, but can within the scope of the general inventive concept, in particular in Structurally modified or similarly used in other Krumm-Stranggiesaanlagen of any metals will. On the other hand, all features that can be inferred from the drawing and the description, including the structural and procedural details, both separately and in any combination of the invention be essential.

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Claims (8)

Bat e claims •1. Process for strand cooling in curved continuous casting plants of metals, in particular steel, in the troughs of the cast strand, which is cast in a continuous mold with a vertical, straight casting space and exiting from this with a solidified strip crust and a molten core all around, is cooled below the mold, preferably by means of spray water, and initially a straight, vertical guide section coaxial to the mold runs through and then it is inevitably bent to the side on a subsequent, curved guide section, characterized in that before the inevitable strand bending is started, ie at least in the area of the vertical, straight strand guide section (3) ^ Each strand cross-section on the outer curvature side (E) is cooled so intensively than on the inner curvature strand side (A) that a peripheral crust (108) on the outside of the curvature that is greater than that of the crust on the inside of the curvature (208) is formed. 2. The method according to claim 1, for strand cooling in curved casting plants, in which the curved strand guide section has a progressively increasing curvature and the cast strand is continuously inevitably bent as it traverses this guide path, thereby identified shows that the more intensive cooling of the curvature outer strand side (E) also continued in the area of the curved guide section (4) and 009833/1321 - t7 - 'is progressively increased speaking of the increasing strand bending. 3. The method according to claim 1 or 2, characterized in that at least in a partial area of the curved F guide section (4) nox the point of complete solidification of the strand cross-section, the difference between the greater cooling intensity of the outer curvature strand side, te (E) and the smaller cooling intensity the inside of the curvature side of the strand (A) so abruptly, or progressively reduced or canceled or reversed in the longitudinal direction of the strand, that the outer curvature band crust (108) and the inner curvature crust (208) of the cast strand (s) assume the same thickness. 4. The method according to claim 3, characterized in that the difference between the greater cooling intensity of the outer curvature side of the strand (E) and the smaller one Cooling intensity of the inside curvature side of the strand (A) Reduction of the cooling intensity of the curvature outer strand side (E) is achieved. 5. The method according to claim 3, characterized in that the difference between the greater cooling intensity of the outer curvature side of the strand (E) and the smaller one Cooling intensity of the inside curvature side of the strand (a) Increase in the inner curvature of the strand side (A) achieved will. 6. The method according to any one of claims 3 to 5, for strand 009833/1321 - 16 - ■ ^■:; ■ "- ■". * cooling in "Erumm continuous casting plants of metals, ins« - special of steel in which the curved strand. guideway has an arcuate course and the glass strand is unique in the transition area between the vertical, straight guide line and the subsequent, circular arc-shaped guiding section is inevitably turned, characterized in that the lowering of the difference between the larger Cooling intensity of the curvature outer strand side (E) and the lesser intensity of the inner curve of the road (A) as soon as possible after the inevitable turn of the cast strand (S) from the vertical straight guide section (3) into the circular arc-shaped guide section (4) begins. 7. The method according to any one of the preceding claims, characterized in that the lateral strand surfaces and the inside of the curvature strand side (E) each with the ' Cooled down to the intensity. 8. Device for carrying out the strand cooling process according to claim 1, in grumm continuous casting plants of metals, in particular steel, in which a coaxial, vertical, straight strand guiding line and a subsequent, curved strand guiding line are below a continuous mold with a vertical, straight line. and water spray nozzles arranged on all sides around the strand track are provided for compartment cooling of the cast strand, characterized in that at least in the area of the vertical, straight strand run the runway (3) 0098 3 3/1321 BATH the water spray nozzles (1Gc) - on the curvature must
Strand side (s) are arranged in a greater number and / or with a smaller mutual distance and / or have a greater spray performance than the water spray nozzles (β) on all other strand sides, in particular on the
curvature inside strand side (A). 00983 371321