EP0107069A1 - Method of continuously casting metals, in particular steel, and continuous-casting plants for carrying out the method - Google Patents

Abstract

In processes and continuous casting plants for semi-horizontal continuous casting with an essentially horizontal mold (5), liquid metal, in particular steel, is introduced into the mold cavity (5b) through a pouring opening on the upper mold wall (5a). A partially rigid strand (30, 30 ') is pulled out laterally from at least one outlet opening of the mold (5) and along two strand guide tracks (40, 40', 41, 41 ') curved in the opposite direction to a lower level than that of the by means of an oscillation device (10), the mold (5) is oscillated. The centers of curvature (43, 43 ') of the first guideway (40, 40') in the strand running direction lie below, the centers of curvature (45, 45 ') of the second guideway (41, 41') in the strand running direction lie above their respective associated guideway.

Description

The invention relates to a process for the continuous casting of metals, in particular steel, steel being introduced from above into a substantially horizontally extending mold and a partially solid strand being drawn out, guided and further cooled from at least one lateral outlet opening of the mold, and continuous casting plants therefor.

It is known (US Pat. No. 3,472,309) to pour an oscillating mold, which is in the form of an inverted T, into the vertical part made of refractory material of this mold steel, and from two adjoining horizontal mold parts, partially solidified strands horizontally opposite to each other. Among other disadvantages, such as poor visibility into the mold, large masses to be oscillated, sealing problems between the individual parts of the mold, etc., a large amount of steel escapes if one of the partially solidified strands breaks. Since the strands are conveyed horizontally, at the level of the mold, steel can flow out both from the mold and from the part of the strand that lies in the direction of the strand after the breakthrough point.

According to a further known solution (USSR-PS 578 155), metal is inserted into the mold cavity from above through an inlet opening in the upper wall of a mold brings. The mold arrangement consists of a straight and a curved part. The intention is that a tear-off point is formed at the transition from the straight to the curved part of the mold, since the weakest, hottest and thinnest point of the strand shell should be located there. In this arrangement, strands emerge from the inclined straight mold part and the likewise inclined curved mold part, the longitudinal axis of which forms an angle with the horizontal. The disadvantage of this arrangement is that the mold cannot be oscillated, since the strand shell formed in one mold part cannot be pushed into the other mold part. As a result, there is too much friction between the mold and the strand formed, and breakthroughs occur. This disadvantage is exacerbated by the fact that the strand has to be constantly forcibly separated at a certain tear-off point.

It is an object of the invention to provide a method and continuous casting plants, the above disadvantages not occurring. Furthermore, the ferrostatic pressure required for a healthy cast product should be ensured with the smallest possible installation height. In particular, if a breakdown occurs on the partially solidified strand, no or as little steel as possible should run out of the strands already formed. According to the invention, this object is achieved in the characterizing parts of the claims.

By guiding the strand after it emerges from the mold to a lower level than that of the mold with two strand guide tracks curved in the opposite direction, it is achieved that no steel flows out of the strand part lying in the direction of the strand after the breakthrough point. This is because the breakthrough point that usually occurs near the mold is higher than that subsequent strand part lies. If the strand is conveyed horizontally, the second curved strand path offers gentle pre-bending of the strand shell. Furthermore, the difference in height compared to the mold creates a higher ferrostatic pressure than horizontal systems, which brings about an improvement in the quality of the cast product.

A partially solidified strand can be conveyed out of only one lateral outlet opening of the mold. In order to achieve higher production, however, it is advantageous to convey partially solidified strands out of both lateral, opposite outlet openings of the mold.

The oscillated mold used can have a straight or curved mold cavity and the metal can be introduced from above with or without a pouring tube. In order to load the strand shell as little as possible, the partially rigid strand emerging laterally from a mold with a straight mold cavity can run through a short, straight guideway before it is bent downwards.

If necessary, a straight guideway can be connected to the first curved strand guide for metallurgical reasons.

The partially solidified strand is subjected to water or an air-water mixture during cooling after it has left the mold via cooling devices and is cooled further. The thickness of the solidified strand shell increases. Since the strand can be curved more with increasing strand shell thickness, it is advantageous, for example to reduce the overall height, to guide the strand in the two curved guideways with a different radius of curvature. For the same reason, it can be advantageous to have at least one of these guideways to provide several different radii of curvature. _D a-in strand example, in the first curved guide track out with decreasing radii of curvature or be bent, and in the subsequent second curved guide track of the radius of curvature can increase again until the strand by a leveling unit in a straight shape with radius of curvature is directed to infinity. Then it can be conveyed horizontally or on an inclined plane.

Especially if the strands do not have to be conveyed horizontally, a downwardly curved guide part can be sufficient to achieve the desired effect.

Strands of different formats can be cast according to the invention. It can be advantageous to cast two different formats on one system at the same time, e.g. on the right side of the plant a slab with a rectangular cross section and on the left side of the plant two blocks with a square cross section, in which case different radii of curvature can be used. So go through e.g. the blooms a first curved guideway with a radius that is larger than the radius of a second guideway adjoining it. The slab discharged in the opposite direction can be progressively guided along a curve with a certain radius in the first guideway and with increasing radii in the second curved guideway.

The continuous caster according to the invention is characterized by an essentially horizontally arranged mold, which has a pouring opening for the introduction of liquid steel on its upper mold wall and has at least one outlet opening for a partially solidified strand, a strand guide for each of these strands contains two strand guideways curved in the opposite direction, the center of curvature of the first guideway in the direction of strand running below this path of the second of this path and the center of curvature of the second curved guideway above its associated path.

It is thereby achieved that the partially solidified strand is guided in an approximately S-shaped strand path to a lower level than that of the oscillating mold.

If necessary for metallurgical reasons, a short, straight strand guideway can be provided in front of and / or in front of the first curved strand guideway.

In order to guide or bend the strand particularly gently, several radii of different sizes can be provided in each of the two oppositely curved strand guide tracks. It is clear that in this case the centers of curvature associated with the respective strand guide path lie on the corresponding side of the path.

If the mold has one or more curved mold cavities, the part of the strand guide track following the outlet openings can advantageously have the same radius of curvature as the upstream mold cavity.

A drive and / or straightening unit can be arranged downstream of the second curved strand guide track, as seen in the strand running direction.

It is particularly advantageous to have a system in which the mold has two opposing, lateral outlet openings for two dividers that are pulled out in the opposite direction staring strands. This can significantly increase productivity.

Advantageous designs and details of the invention are described in more detail with the aid of the following description of the figures.

• Fig. 1 eine Ansicht der Stranggiessanlage, teilweise geschnitten,
• Fig. 2 eine Ansicht des Eingiessbereiches des Stahls in die Kokille, teilweise geschnitten,
• Die Figuren 3 - 6 verschiedene Möglichkeiten des Strangbahnverlaufs, schematisch dargestellt.

Show it:

• 1 is a view of the continuous caster, partly in section,
• 2 is a view of the pouring area of the steel into the mold, partially cut,
• Figures 3 - 6 different possibilities of the strand path, shown schematically.

1, metal, in particular steel, is transferred from a pan 1 via a ladle pouring tube 2 into an intermediate container 3 and from there via a pouring tube 4 into a water-cooled, metal mold 5 provided with two outlet openings. The metal inflow is in each case via regulating devices (not shown) , such as Plug and / or slide, controlled.

The pouring tube 4 extends through a pouring opening 20 of the upper mold wall 5a of the mold 5 and is immersed in the mold 5 under the bath level of the steel. The steel is introduced through the pouring tube 4 into the mold cavity 5b of the mold in such a way that no strand shell 5c can form along the mold wall in the immediate inflow region. This ensures that both strands 30 and 30 ', formed in the mold 5, can be conveyed out of this mold independently of one another in the opposite direction. In the example shown, the mold 5 has a curved mold cavity 5b and is oscillated along an arc via an oscillation device 10 with an eccentric drive. Of course other known oscillation devices can also be used. The oscillated mold is guided over handlebar 100.

After the strands 30, 30 'have emerged from the two opposite side outlet openings 5d of the mold 5, they are guided through associated strand guides 15 and 15'. Each of these strand guides has a number of strand guide tracks 40, 41 ', 42 and 40', 41 'and 42', the extent of which is represented by vertical, dashed lines. 1, the two strand guides 15 and 15 'are arranged symmetrically to one another. Immediately after it leaves the mold, the strand is guided along the curved strand guide track 40, the center of the associated radius of curvature 44 being below this strand guide track 40. The radius of curvature 44 corresponds approximately to the radius of the circular arc on which the mold 5 is oscillated. This second curved strand path 40 is followed by the second curved strand path 41, the center of curvature 45 of its radius of curvature 46 being above this strand guide path 41, and the radius of curvature 46 roughly corresponding to the radius of curvature 44 of the first curved strand guide path 40. Along these curved strand guideways 40 and 41, the strand is guided by rollers 12 and by; Coolant emerging from spray nozzles 13 is further cooled. If a breakthrough occurs on this semi-horizontal system, no significant amount of steel flows out of the strand part lying in the strand running direction after the breakthrough point.

The two partially solidified strands 30 and 30 'are pulled out from the opposite outlet openings 5b of the mold 5 by drive rollers 9 and 9'. Since both strands 30 and 30 'are not connected to one another by a strand shell, the pull-out speed of both strands can be different from each other. The pull-out rollers 9 and 9 'belong to an essentially horizontal strand 43 and 42', respectively.

2 shows details of the pouring area into the mold 5. The pouring tube 4 extends through the opening 20 provided on the upper wall 5a of the oscillating mold 5 to below the bath level in the mold. The pouring tube 4 is arranged at a distance 25 from the upper mold wall. This distance 25 must be greater than the oscillation stroke of the mold 5 so that the pouring tube is not damaged during the oscillation. Cooling channels 7 are provided for cooling the mold, in which cooling liquid circulates. An electromagnetic coil is arranged around the pouring tube 4 on the upper wall 5a of the mold 5 above the sprue opening 20. This coil 11 generates an electromagnetic field, which causes downward forces acting on the bath level. This prevents the liquid steel from solidifying in the region of the pouring opening 20 and thereby giving rise to breakthroughs. Furthermore, the steel prevents the steel from escaping upward due to the ferrostatic pressure.

The pouring tube is provided with outlet openings 4a, through which hot steel is directed directly against the mold wall 5c in order to prevent the formation of a continuous strand shell along the mold wall in the intermediate region of the strands 30 and 30 '.

FIGS. 3 to 6 show different possibilities of how the strand tracks can run according to the invention for one or more strands. The respective form is chosen according to the relevant needs, e.g. according to the type and size of the strand format to be cast, the batch weight, the space, etc.

For the sake of simplicity, only the center lines of the corresponding strand guideways were shown in FIGS. 3 and 6 by dash-dotted lines. The guideways themselves are formed from guide rollers or guide rails, not shown, to which the corresponding devices for the secondary cooling of the strand are assigned. To simplify the illustration, two different strand guides, to the left and right of the mold, are assigned to each mold according to FIGS. 3-5. However, it goes without saying that the mold 5 is usually provided with strand guides which are identical on both sides. However, should one side of the mold e.g. a semi-rigid strand with slab format, but one or more semi-rigid strands with bloom block format are generated on the opposite side, the strand guides in the course and their design to the left and right of the mold can accordingly be different. For better clarity, the individual strand guide sections are separated by dashed, vertical lines.

According to FIG. 3, liquid steel is introduced from a pouring vessel 3, for example an intermediate container, into a horizontally arranged cooled copper mold 5 which is oscillated in the direction of the double arrow along an arc of a radius R. According to the illustration on the left of the mold 5, the strand is guided in a first, downwardly curved guideway 40 'with the radius of curvature R 1 and the center of curvature M 1 lying below the strand path. Immediately afterwards, the opposite curved guideway 41 with the radius of curvature R 2 and the center of curvature M 2 passes through. This center of curvature M 2 lies above the strand guideway 41 '. The strand is then pulled out by a drive straightening unit 14 ', which has driven rollers 9', and is guided along a horizontal guideway 42 '. With the help of this Before the start of casting, the drive leveling unit also feeds the start-up strand necessary for closing the mold opening into the mold along the strand guide. The radii of curvature R 1 and R 2 of the oppositely curved guideways 40 'and 41' have the same size here. This offers various advantages in terms of interchangeability, maintenance, etc.

An arrangement is shown on the right-hand side of FIG. 3, in which a straight guide section 47 with an infinite radius of curvature R is provided between the two oppositely curved guide tracks 40, 41 with the radii R 3 and R 4. With this strand guide, intended for guiding and supporting a larger format, a higher ferrostatic pressure is built up in the strand.

In the case of a continuous caster shown in FIG. 4 on the left, a mold 5 'with a curved mold cavity and a radius R 1 is connected to an oscillating mold 5 with a curved mold cavity. Before straightening and conveying the strand horizontally in section 42 ', it is guided, following the curved guide track 40, along a strand guide track 48' which has different radii of curvature R 5, R 6 and R 7. These radii of curvature can progressively increase in the direction of the strand. With this somewhat more complex solution, the strand is guided as gently as possible. As shown on the right-hand side of FIG. 4, in this embodiment the strand, following the downwardly curved guideway 40 with the radius R 3, runs through a rectilinear guideway 49 inclined to the horizontal, in which it is also directed and conveyed by pull-out rollers, not shown becomes.

According to the embodiment shown on the left in FIG. 5 the partially solidified strand, after it emerges from the mold, is initially guided along a horizontal strand path 50 ', with a radius of curvature R infinite. This is followed by a guide track curved in the opposite direction in accordance with 41 'of FIG. 3 or 48' in accordance with FIG. 4 with a subsequent driving directional unit 14 'in the horizontal part.

On the right side of FIG. 5 is shown schematically that the strand by a short horizontal strip guide member 50 is guided in a downward curving portion 51, a plurality of radii of curvature R 7, R 6, R 5 has the ^{g-directional} in Stran progressively can lose weight. After an intermediate straight but inclined part 47, the strand is guided along a second curved strand guide path 48 with the radii R 5, R 6, R 7, which can increase progressively in the direction of the strand. A horizontal part with a drive leveling unit 14 follows.

The associated centers of curvature of the individual radii of curvature are no longer designated in detail in FIGS. 4 and 5 as end points of the radii R 1 -R 7.

6, the mold has rectilinear mold cavities 56 'which are inclined at an angle to one another. This is followed by the strand guideways 52, 52 ', which form an angle 53 with the horizontal. The mold oscillates on a circular arc 110 with the radius R and the strand tracks 52 and 52 'form 5 tangents to this circular arc in the outlet openings of the mold.

Claims (23)

1. A method for the continuous casting of metals, in particular steel, steel being introduced from above into a substantially horizontally extending mold and a partially solid strand being drawn out, guided and further cooled from at least one lateral outlet opening of the mold, characterized in that the Strand in two strand guideways curved in the opposite direction to a lower level than that of the mold and then straightened. 2. The method according to claim 1, characterized in that the strand is guided in a straight guideway before it is guided in the first curved strand guideway. 3. The method according to claim 1, characterized in that the strand is guided in a straight guideway after being guided in the first curved strand guideway. 4. The method according to claim 1, characterized in that the strand is guided before and after it is guided in the first curved strand guide track in a straight guide track. 5. The method according to claim 1, characterized in that the strand is guided in curved guideways which have different radii of curvature. 6. The method according to claim 1, characterized in that at least one of the two curved guideways has several different radii of curvature. 7. Method for casting metal strands, in which metal, in particular steel, is introduced into a metallic, essentially horizontally extending mold, through an opening in the upper wall thereof, and partially solidified strands are drawn out, guided and pulled from two opposite, lateral outlet openings of the mold are further cooled, characterized in that the strands are guided in a downwardly curved guide track immediately after they exit the mold and are then straightened. 8. The method according to claim 7, characterized in that the strand between the mold and the curved guide track runs through a straight strand track. 9. The method according to claim 7 or 8, characterized in that the strand is guided along the curved guideway with a plurality of radii of curvature. 10. The method according to claim 7, characterized in that the partially solidified strands formed in the mold are inclined to each other and to the horizontal and are guided after their exit from the mold in a straight, inclined at an angle to the horizontal guide track. ll. A method according to claim 7, characterized in that the strands are guided along the curved guideways immediately after they emerge from the mold. 11, continuous casting plant for casting metal, in particular steel, with a substantially horizontally extending mold, which has an opening for the supply of steel and at least one outlet opening for one strand at its top, and with a subsequent strand guide for each strand, characterized that the strand guide (15, 15 ') has two guideways (40, 41, 40', 41 ', 51, 48) which are curved in the opposite direction with a predetermined radius of curvature (44, 46, 44', 46 ') , the center of curvature (43, 43 ') of the first guideway (40, 40', 51), viewed in the strand running direction, lies below its associated guideway (40, 40 ', 51) and the center of curvature (45, 45') of the second guideway ( 41, 41 ', 48) lies above its associated guideway (41, 41', 48). 13. The apparatus according to claim 12, characterized in that the second guide track (41, 41 ', 48) is followed by a drive leveling unit (14, 14'). 14. The apparatus according to claim 12, characterized in that a linear guide track (50) is arranged in the strand running direction in front of the first curved guide track (40, 40 ', 51). 15. The apparatus according to claim 12, characterized in that a straight guide track (47) is arranged in the strand running direction after the first curved guide track (40, 40 ', 51). 16. The apparatus according to claim 12, characterized in that a straight guide track (50, 47) is arranged before and after the first curved guide track (40, 40 ', 51). 17. The apparatus according to claim 12, characterized in that the first and second curved guideway have different radii of curvature (44, 44 ', 46, 46'). 18. The apparatus according to claim 12, characterized in that at least one of the two curved guideways has a plurality of different radii of curvature (R 5, R 6, R 7). 19. The apparatus according to claim 12, characterized in that the mold (5) has a curved mold cavity (5b) and the first curved guide track (40, 40 ', 51) has the same radius of curvature as the mold cavity of the mold. 20. Continuous casting installation for casting metal, in particular steel, with an essentially horizontally extending mold, which has an opening for the supply of steel and two opposite outlet openings for two partially solidified strands as well as a strand guide, characterized in that that the mold (5) is connected to an oscillation device (10), that the strand guide has a curved guideway (40, 40 ', 51) for each strand and a drive leveling unit (14, 14') is present after this strand guideway. 21. The apparatus according to claim 20, characterized in that the curved strand guideways (40, 40 ') have different radii of curvature. 22. The apparatus according to claim 20, characterized in that at least one of the two curved strand guide tracks (40, 40 ', 51) has a plurality of different curve radii (R 5, R 6, R 7). 23. Continuous casting plant for casting metal, in particular steel, with an essentially horizontally extending mold, which has an opening on the top for the supply of steel, a straight mold cavity and two opposite outlet openings for two partially solidified strands drawn out in the opposite direction and being provided with a ^- in the strand guide, characterized in that the mold (5) is connected to an oscillation means (10), and that the outlet openings of the mold each have a short straight guideway (50, 50 ') followed by a curved guide path (40' , 51) and the following straightening unit (14, 14 ') for the production of straight strands follows.

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