EP1379344B1 - Ingot mold for a continuous casting installation for metal and method for influencing the taper angle of the sidewalls of the ingot mold - Google Patents

Abstract

The invention relates to an ingot mold (7) for a continuous casting installation (1) for metal, comprising a support frame with two narrow walls (15) and two broad walls, at least one of the respective walls being provided with a parabolic taper angle (P0) on its inner side (15a) facing a mold cavity (F) delimited by the narrow walls and the broad walls. The aim of the invention is to provide means for influencing the taper angle of the respective wall (15) that is flexible in the operating state, said means being independent of the cooling water system. To this end, at least one mechanical pressure element (21) is provided that exerts an adjustable pressure p on the side of the wall facing away from the mold cavity (F). By superimposition of the deformation exerted by the respective pressure elements (21) the parabolic taper angle (P0) also allows for a desired parabolicity (PS). The invention also relates to a corresponding method.

Description

The invention relates to a mold for a continuous casting plant for metal, in particular for steel, comprising a support frame on which two narrow side walls and two broad side walls are arranged, at least one of the respective side walls on their inner side leading to one through the walls formed mold cavity indicates, provided with a parabolic taper is as well as according to the other features of the preamble of Claim 1. In addition, the invention relates to a method for influencing the taper.

It is known to use molds for continuous casting plants or their walls with parabolic Taper. With these molds there is a certain parabolic Contour into the side facing the mold cavity of the casting mold, for example by milling or casting. Reason for such parabolic Contours is the approach, the mold shape is inherent adapt the shrinking course of the strand or the strand shell, in order to avoid the risk of cracks forming in the strand shell as far as possible. Appropriate parabolicity, i.e. Curvature of a parabola, can be used depending on the material to be cast respective other operating parameters, such as casting speed and cooling, determined by calculations and the side wall accordingly be formed. A mold with a constant parabolic taper is consequently only for certain ones on which the respective invoice is based Operating parameters optimal. As soon as the operating parameters deviate from this, the risk of errors increases.

From EP 0 686 445 A1 are molds with side plates or side walls linear taper known. The respective side walls are in the operating state especially heated at the level of the meniscus than in others Wall areas, and as a result the side walls bulge outwards, i.e. away from the mold cavity. It is now proposed to use Control of the cooling water used for cooling the mold is such apply hydraulic back pressure to the bulging side wall, so that their (not intended) deformation is compensated for and the side wall resumes its original linear surface. Therefor is between the side wall of the mold and a supporting frame outer wall and the space thus formed is provided with an intermediate wall and between the side wall and the intermediate wall, which are at a distance from the side wall is adjustable, led under pressure cooling water. In this way it is achieved that on the one hand compensates for the negative curvature of the side wall and on the other hand the space between below formed the side wall and the strand shell reduced and thus the heat transfer coefficient is increased.

However, this regulation of the linear conicity by means of water pressure shows that Disadvantages that enormous hydraulic forces are necessary to the back pressures required to compensate for changes in taper of the side walls. The influencing of partial areas should done through a chamber system, which makes great differences in the specific Pressure ranges of the coolant in the respective chambers required. moreover the cooling water, which should ensure optimal cooling of the mold, another task overlaid, which adversely affects the cooling properties effect.

JP 05 177310 A describes a hydraulic system as a means of influencing the shape of a narrow side wall of a mold for casting metal, which has a parabolic shape. This system continues either from a load point L2 with support points L1 and L3 at the top and bottom the narrow side wall of the mold together or from just one support point with two load points at which the pressure of the hydraulic system is transferred to the narrow side. Overall, the load and stabilization points apply on the back of a frame, the one on the back the narrow side wall are arranged.

The invention is therefore based on the object, a mold and a Process of the type described with the possibility of adjusting the taper to propose the side walls, being the important parameter of the cooling water only kept free for cooling the mold side walls and not with other tasks are superimposed and none additional stabilizing elements of the pressure applying system are necessary.

The invention is achieved by a mold with the features of claim 1 and by a method having the features of claim 10. Advantageous Further developments are described in the subclaims.

The essence of the invention is to equip a mold with agents for influencing it the conicity of the respective flexible in the operating state, in the sense of deformable, side wall, in particular narrow side wall, and with control means for this purpose, the influencing means at least one pressure element include mechanical type, each facing away from the mold cavity Side of the side wall exerts an adjustable pressure, and wherein by superimposing those applied by the respective printing elements Deformation with the parabolic taper a desired overall parabolicity is adjustable. Parabolic taper is used in this context a parabolic contour approximating the strand shell shrinkage understood the apex of the parabola at the lower end of the narrow side wall. Due to the deformation caused by the pressure elements the overall parabolicity is seen over the total length of the narrow side wall changed. Spatially limited influences are also conceivable.

According to the method, the actual parabolicity of a narrow side wall is proposed with parabolic taper to determine and a target parabolicity this narrow side wall by superimposing the actual parabolicity using a Adjust the pressure influence of at least one mechanical pressure element, the respective pressure element over a defined adjustment path to exert a defined pressure p on that facing away from the mold cavity Moved side of a flexible narrow side wall in the operating state becomes.

Overall, this optimal adaptation of the mold side walls results uniform heat dissipation to the respective shrinkage behavior of the strand and therefore a lower risk of surface defects. In addition, the risk of breakdown for the strand is reduced. Overall there are higher casting speeds reachable.

According to a particularly preferred embodiment, the respective Mechanical pressure elements. The term push pin limits the pressure elements, however, are not elongated on training with yourself extending body and a tip for selective or partial force application. Above all, a flat application of force through the pressure pins Compensation of the respective curved side wall surface can be achieved. This is possible by pressing pins over a flat intermediate piece on the Attack sidewall or by the body or the end of each Push pins are not pointed, but flat.

The number of printing elements is not limited to a single printing element. In particular, it is favorable that a plurality or a large number of such Pressure elements are used, which are then, for example, flat Pressure is arranged in groups or certain formations.

With regard to preferred positions, claims 5 and 6 propose that a pressure element at the level of the introduced liquid Metal is arranged. At the same time, preferably several printing elements can be used here are arranged to be just at the level of the meniscus Melt to compensate for bulging. preferred catfish this pressure element or these several pressure elements should be approximately in the center be arranged to the central longitudinal axis of the narrow side wall to the introduction distribute the force evenly over the two parts of the narrow side wall.

According to the invention, the pressure elements on the Support frame of the mold arranged and on a defined adjustment the narrow side wall and movable back, preferably movable. Then comprise at least the control means for moving the respective pressure elements a drive. With this drive, which is preferably designed as a linear motor is connected to a computing unit in which a certain selection of operating parameters of the continuous casting process and the control signals transmitted to the drive.

According to the invention, the support frame comprises the Chill mold on the respective mold sides, especially on the narrow sides, an inner plate and an outer spaced parallel thereto Plate. The inner plate is with the side of the narrow side wall facing away from the mold cavity points away, directly connected, for example, it is screwed to it. The narrow side wall consists of a copper plate. Through the Connection of the narrow side wall to the inner plate of the support frame a doubled wall is created, which is deformable in the operating state. The two Plates, i.e. the inner and outer plates are on the top and bottom Connected to each other via stiffeners for stiffening.

On the side of the inner plate facing away from the mold cavity are one or two-piece receiving elements are provided for one or more pressure pins, i.e. these receiving elements can be molded or detachably on the inner Plate be arranged. These receiving elements are, for example, cuboid, preferably plate-shaped, over the width of the narrow side wall extending, trained. So it can be a receiving element for several or several receiving elements can be provided for one pressure pin each. These receiving elements have a recess into which the first end the push pin, i.e. the end that faces the mold cavity engages.

The outer plate takes over the guiding function for the respective push pin. For this purpose, it has at least one opening which is shaped so that it Cross section corresponds to the outer surface of the respective pressure pin. Here lies an opening at the same height or approximately at the same height with a Receiving element, each seen from the support plates. By means of a Single drive or a common drive, the respective push pins, which, guided in the opening and engaged with its tip, if present coming with the recess of the respective receiving element, parallel or at a certain angle to the support plates, via an adjustment path move towards the mold cavity and back.

Fig. 1

eine schematische Übersicht einer Stranggießanlage für Stahl mit einer erfindungsgemäßen Kokille, deren Konizität der Seitenwände mittels des erfindungsgemäß vorgeschlagenen Verfahrens beeinflußt wird;

Fig. 2

schematisch einen Ausschnitt eines Kokillentragrahmens mit einer Schmalseitenwand, im Schnitt dargestellt;

Fig. 3

schematisch den Schnitt A-A der Fig. 2.

Further details and advantages of the invention emerge from the subclaims and from the following description, in which the embodiments of the invention illustrated in the figures are explained in more detail. In addition to the combinations of features listed above, features alone or in other combinations are also essential to the invention. Show it:

Fig. 1

a schematic overview of a continuous casting plant for steel with a mold according to the invention, the taper of the side walls is influenced by the method proposed according to the invention;

Fig. 2

schematically shows a section of a mold support frame with a narrow side wall, shown in section;

Fig. 3

schematically the section AA of FIG. 2nd

Figure 1 gives a schematic overview of a continuous caster 1, in the the mold according to the invention is used. The continuous caster shown is intended to serve as an example for a large number of possible plant types. The The mold according to the invention can be used as a plate mold for the production of slabs or blooms, serve as a tube mold for the production of billets. Not Use for the production of thin slabs is also excluded.

The continuous caster 1 shown consists essentially of a ladle 2, from which the liquid metal 3 via a shadow pipe 4 into the distributor 5 and from there through a diving spout 6 into the mold 7. Before the start of casting the bottom of the mold is closed with the so-called cold strand. As soon as the prescribed bath level is reached, it will be in its edge zone solidified strand 8 first with the help of the cold strand and later through the drive rollers pulled out of the mold 7. To i.a. Avoid braking increases and To improve the casting quality, the strand 8 runs in the embodiment shown after exiting the mold 7 through a stirring coil 9 and then through a secondary cooling zone 10. Then directional drivers 11 close on. After complete solidification, the strand can be carried by passengers Cutting torch or scissors 12 are divided and then reaches sorting beds 13th

According to the invention, such a mold 7 is used for a continuous caster with a parabolic taper of the side walls, especially the narrow side walls, equipped with mechanical pressure elements. Figure 2 shows in section a narrow side wall area 14 of this mold, which in its entirety (not shown) two broad side walls and another narrow side wall having. The mold 7 comprises a support frame which is on the side of the respective narrow side walls 15 of two parallel spaced Plates, namely an inner plate 16 and an outer plate 17, which in turn at the top and end via support plates 18a, b in the form of elongated sheets are connected. These plates 16, 17 as well Support plates 18a, b form the so-called end plate carrier. The end plate carrier also has the function of being worked into the narrow side wall 15 to seal vertical cooling channels to the outside. On the cooling water system will be discussed further below.

The narrow side wall 15 or the copper plate forming this wall is detachably connected to the inner plate 16, namely with its side 16a facing the mold cavity F, for example by screwing, here indicated by 19a, b. The side 15a of the narrow side wall 15 facing the mold cavity or its "hot side" has a parabolically shaped contour or a parabolic taper P ₀ . A receiving element 20 for a pressure pin 21 is formed in one piece on the inner plate 16, namely on its side 16b facing away from the mold cavity. This receiving element 20 has - as the comparison with FIG. 3 shows - rectangular dimensions and extends entirely along the width of the inner plate 16. It is approximately at the level of the meniscus of the melt and approximately in the center of the mold width (see FIG. 3) Arranged pressure pin 21, the first end 22, which is conical in the embodiment shown, comes into engagement with a corresponding recess 23 (only indicated schematically here) in the receiving element 20. The push pin body is held by the outer plate 17, which has a corresponding opening 24, whose dimensions correspond approximately to the cross section of the push pin 21. The pressure pin 21 is guided through this opening 24 of the outer plate 17 and also supported by this. At its second end 25 or outer end, the pressure pin 21 is provided with a drive 26, here a linear motor. Basically, all known drives are conceivable, which can bring about the desired movement or the adjustment path of the pressure element. The linear motor moves or moves the pressure pin 21, held by the outer plate 17, into the receiving element 20 or its receptacle 23 and back. If the pressure pin 21 or its first end 22 is moved into the receiving element 20 or moved by the drive over a certain adjustment path (the arrow indicates the adjustment path), the applied force is distributed over the area extending across the width of the narrow side wall 15 Receiving element 20 and from there onto the narrow side wall 15. The parabolic contour incorporated in the narrow side wall 15 is superimposed by the pressure influence or the resulting deformation of the inner plate 16 which is flexible under operating conditions and the flexible narrow side wall 15.

The cooling water circuit for the mold or the narrow side wall 15 shown is not required for this deformation in the solution according to the invention. Figure 2 makes it clear that the cooling channels introduced into the mold wall 27, which run parallel to the longitudinal axis of the mold, by means of pipe sockets 28a, b, which are integrally formed on the inner plate 16, with corresponding Cooling water inlet and outlet lines 29a, b are connected. It is recommended to the narrow side wall 15 blind holes as cooling channels. to Stabilization of the support frame or the plate construction are on the outer Plate 17 backwards, i.e. extending away from the mold cavity Stiffening plates 30 and 31 attached, which also house the drive motor.

According to the method, the actual parabolicity of the respective narrow side wall 15 is determined with a corresponding measuring device (cf. FIG. 1) and the corresponding information x together with a selection of current operating parameters, such as continuous casting speed, cooling, in particular also the type of steel to be cast with its individual solidification properties. etc. transmitted to a computer unit 33. From this, the computer unit 33 calculates a target parabolicity and transmits corresponding actuating signals y to the drive 26 of the pressure element. The target parabolicity P _{S is set} by superimposing the actual parabolicity P ₀ with the aid of a defined adjustment path of the pressure pin and thus a defined pressure application. The total results in a changed, desired parabolicity (tendon height). The parabolicity can thus be controlled and adapted to the current operating state by different adjustment paths of the linear drive.

Claims (11)

1. An ingot mould (7) for a continuous casting installation (1) for metal
   which comprises a supporting frame, on which two narrow sidewalls (15) and two broad sidewalls are arranged,
   with at least one of the sidewalls being provided with a parabolic conicality (P₀) on its inner side (15a) that points to a mould cavity (F) formed by the narrow sidewalls and the broad sidewalls, and
   with means, as well as corresponding control means (26, 33), being provided for influencing the conicality of the respective sidewall (15) that is flexible in the operating state, wherein said control means comprises at least one mechanical pressing element (21) that respectively exerts an adjustable pressure upon the side of the sidewall that faces away from the mould cavity (F), and wherein a desired parabolic shape (P_s) can be adjusted by superimposing the parabolic conicality (P₀) with the deformation caused by the respective pressing elements (21)
   characterized in that
   the supporting frame of the ingot mould contains on the respective ingot mould sides, particularly on the narrow sides, an inner plate (16) and an outer plate (17) that is arranged parallel to and spaced apart from the inner plate, in that the side of the inner plate (16) that faces away from the mould cavity (F) is provided with a receptacle element (20) for the pressing element (21), into which the first end (22) of the pressing element engages, and in that the outer plate (17) fulfills the function of guiding the pressing element (21).
2. The ingot mould according to Claim 1,
   characterized in that
   the respective mechanical pressing elements (21) comprise movable pressing pins.
3. The ingot mould according to Claim 1 or 2,
   characterized in that
   the pressing elements (21) are arranged on the supporting frame and can be displaced forward and backward on the sidewall by a defined adjusting distance.
4. The ingot mould according to one of Claims 1-3,
   characterized in that
   one pressing element (21) is arranged at the elevation of the meniscus of the introduced liquid metal.
5. The ingot mould according to one of Claims 1-4,
   characterized in that
   the respective pressing elements (21) are approximately arranged centrally referred to the longitudinal center line of the sidewall.
6. The ingot mould according to one of Claims 1-5,
   characterized in that
   the control means for moving the respective pressing elements (21) comprises at least one drive (26), as well as an arithmetic unit (33) that is connected to the drive and into which the operating parameters of the continuous casting process are input, wherein the arithmetic unit transmits adjusting signals (y) to the drive (26).
7. The ingot mould according to Claim 6,
   characterized in that
   the drive (26) consists of a linear motor.
8. The ingot mould according to one of Claims 1-7,
   wherein the supporting frame comprises on the narrow sides an inner plate (16) and an outer plate (17) that is arranged parallel to and spaced apart from the inner plate, wherein the inner plate (16) is directly connected to the outer side (15b) of the narrow sidewall (15) that points away from the mould cavity (F) and this double wall is flexible in the operating state, and wherein the two plates (16, 17) are respectively connected to one another on their upper and lower sides by means of supporting plates (18a, b),
   with at least one receptacle element (20) for a pressing pin or for several pressing pins, wherein the respective receptacle element (20) is arranged on the side (16b) of the inner plate (16) that faces away from the mould cavity (F), and wherein the respective receptacle element contains at least one recess (23), with which the first end (22) of the respective pressing pin engages,
   with at least one opening (24) in the outer plate (17) that is shaped such that it corresponds to the cross section of the outer surface of the respective pressing pin, wherein an opening (24) lies, respectively viewed from one of the supporting plates (18a, b), at the same elevation or approximately the same elevation as the receptacle element (20),
   and with at least one pressing pin that can be displaced in the direction of the mould cavity (F) and back by an adjusting distance, namely parallel or at a certain angle referred to the supporting plates (18a, b), while being guided in the opening (24) and engaging with the recesses (23) of the respective receptacle element (20) with its first end (22).
9. The ingot mould according to Claim 8,
   characterized in that
   the outer plate (17) contains at least one lateral reinforcing plate (31, 32) that is arranged perpendicular to the outer plate (17) and points away from the mould cavity (F).
10. A method for influencing the conicality of at least one sidewall of an ingot mould (7) for a continuous casting installation (1) for metal, wherein said ingot mould comprises a supporting frame, on which two narrow sidewalls (15) and two broad sidewalls are arranged, wherein the actual parabolic shape (P₀) of a sidewall with parabolic conicality is determined and the nominal parabolic shape (P_s) of this sidewall is adjusted by superimposing the actual parabolic shape (P₀) with a pressure exerted by means of at least one mechanical pressing element (21), and wherein the respective pressing element (21) is displaced on the side of a sidewall (15) that faces away from the mould cavity (F) by a defined adjusting distance in order to exert a defined pressure p upon this sidewall that is flexible in the operating state,
    characterized in that
    the pressing element (21) engages into a receptacle element (20) on the side of an inner plate (16) that faces away from the mould cavity (F), and in that said pressing element is guided by an outer plate (17) that is arranged parallel to and spaced apart from the inner plate (16).
11. The method according to Claim 10,
    characterized in that
    the nominal parabolic shape (P_s) is calculated in dependence on individual operating parameters, namely the casting speed and/or the frictional properties of the billet and/or the temperature conditions, particularly in the narrow sidewall, and/or the properties of the metal being cast.

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