KR19990052473A - METHOD AND EQUIPMENT FOR THE PRODUCTION OF SHEET SLABS IN CONTINUOUS CASTING EQUIPMENT - Google Patents

Abstract

In order to ensure the best surface quality and internal quality of the billet, the process and apparatus of a sheet metal slab installation having a solidification thickness between 60 and 120 mm and a maximum output of about 3 mio t / a and a maximum casting speed of 10 m / The first segment (0) of billet induction, which goes directly down vertically, must be preempted by a billet reduction, also called continuous casting,

- A segment (1) arranged just below the first segment (0) precedes the bending of the billet through several bending points in the inner circle

- The billet in front of the final solidification is reverse bent to the horizon via several reverse bending points.

Methodological features and equipment features can be explained by the following characteristics of continuous casting equipment of single core:

- Hydraulic driven vertical die casting with a length of 1.2m, which has been opened exactly 80mm from the meniscus in the horizontal direction, has an exit thickness of 100mm in the narrow range,

- Segment 0 of 3 m length is formed as a gear for billet thickness reduction from 100 to 80 mm with a billet deformation speed of up to 1.11 mm / s,

- Segment 1 has five bending points,

- Segment 4 has five related points,

- Segments 5 to 13 are formed within the horizontal extent of the billet induction.

Description

METHOD AND EQUIPMENT FOR THE PRODUCTION OF SHEET SLABS IN CONTINUOUS CASTING EQUIPMENT

The present invention is primarily for vertical slabs for sheet metal slabs for casting steel up to 80 mm at a set thickness of 60 to 120 mm and a casting speed of 10 m / min and a maximum casting capacity of about 3 mio / t / a, To a method and apparatus for producing slabs in a continuous casting facility representing dies.

As already known, the thin plate slab installation with reduced billet thickness is equipped with a pair of one or two foot rollers realized by a continuous casting installation and is mainly used in the continuous casting die casting in the so-called "segment 0" . Here, when the casting speed is max. 6 m / min, the thickness of the billet is reduced from 65 mm to 40 mm via the metallurgical length of about 2 m, that is, the total length of this segment (or stand) which is not vertically connected. This design information leads to a billet thickness reduction of up to 38% and a deformation rate of 1.25 mm / s at billet thickness.

During this delay time of the billet using the casting core, billet shells of about 8 to 12 mm thick, conditioned through the belly out camber between continuous casting equipment rollers when entering segment 0, are strongly deformed. This internal deformation increases with increasing casting speed and equipment height or iron static pressure and decreases with the reduction of roller distance. It should be noted here that the roller diameter has never been lowered in the mechanical manufacturing category of 120 to 140 mm (mechanical load, in particular structural limitations in the middle loaded roller). One possible mechanical manufacturing solution would be to describe a sliding plate called a " grid ", which is unsuitable for performing billet thickness reduction.

These internal deformations are inherent in normal continuous casting

- Uneven areas of the billet between rollers

- Bending billets on a vertical line in an internal arc (circular arc)

- the direction of the billet towards the horizon

- Ideal in billet guidelines

- Exit of roller

- Strike of the roller

- The tensile strength

.

In addition, it is possible to consider deformations occurring through so-called continuous casting rolling in segment 0 and in billet thickness reduction to these internal deformations and surface-deformations. This particular internal transformation inherently accumulates deformation that has already occurred in segment 0, which occurs through bending processes in the vertical arc on the dents and inner arcs of the billet. This accumulation of each particular variation reaches a critical point and results in a rupture both inside and outside the casting shell.

This manner of additional casting shell loading, for example through continuous casting or thickness reduction during solidification, at a long segment 0 of 2 m immediately below the die cast, is described in the patent specifications DE 44 03 048 and DE 44 03 049, An example of the diagram is shown in detail.

According to Fig. 1, one or two pairs of foot rollers connect a segment 0 of length 2m to a vertically cast die 1m long, in which a billet passes through several phases and bends in the inner arc, and its thickness is reduced. This concurrent process or deformation leads to a point-wise deformed global deformation that occurs in flexural deformation (D-B) and continuous casting rolling (D-Gw). The total strain (D-Ge) acting on the billet shell can be greater than the critical limiting strain (D-Kr) and can lead to rupture of the internal and external billet shells. These hazards multiply with increasing casting speed, are conditioned through the roller distance or roller diameter at segment 0, and can not be reduced at the machining limit.

Another point to note in the description of this problem is that the limit strain (D-Kr) is special for every steel product. Thus, for example, the absorption of deformations and the associated drawing frequency without the consequence of rupture has reached a critical point, for example, compared to microalloy API X 80-steel products.

Furthermore, the pure melt phase or the formation or extension of the superheated melt in the billet, which is represented by the straight line G1 depending on the casting speed, has a significant influence on the billet inner quality. In the example shown in FIG. 1, the deepest liquid-temperature or pure melt stage at the center of the billet reaches up to about 1.5 m at a casting speed of 5 m / min at the bottom of the meniscus and up to 3.0 m at a VG of 10 m / min. Below this point is a two-phase zone via the entire billet thickness, preceded by a zone consisting of melting and crystallization, with an increasing distance in the direction of the sump edge, or a final solidification in proportion to the dissolution rate for the crystalline stock .

At half the distance of 50% of the crystal stake, for example at the VG 5 m / min, between the deepest liquefaction point of 1.5 m and the final solidification at about 15 m, ie, 8.25 m (1.5 m + (15 m-1.5 m) = 8.25 m) (GW-50%), the dissolution / crystallization process has a viscosity of 10 000 cP. The two-phase zone at a crystallinity ratio of 80% accommodates 40 000 cP viscosities and conversely the pure dissolution step up to the deepest liquefaction point presents a viscosity according to the steel product of only about 1 to 5 cP, The partial viscosity does not actually rise until the final settling and is thus invariant.

If you want to relate these viscosities to well-known everyday materials in a two-phase zone, you can recall the following materials:

- water 1 cP = 10exp3 Ns / m exp2 at 20 ° C

- Olive oil 80 cP at 20 캜

- Honey 10 000 cP at 20 ° C

- Nieve 40 000 cP at 20 ° C

- Margarine 100 000 cP at 20 ° C

- Bitumen At 20 캜 1000 000 cP

These viscosities indicate that good grinding of crystals through good billet convection and hence billet thickness reduction at the core of the billet should also be based on the crystal / melt-structure, that is, at the maximum casting speed, Phase range in the core and the penetration moieties for the pure dissolution step or the superheat range or the increase of the oxide are no longer present. These conditions related to the purity of the oxide allow segment 0 to be the first vertical and the second to contribute only to the reduction of the billet thickness and the absence of additional bending of the billet.

In FIG. 1, which shows the above mentioned bad conditions, the superheat zone or the deepest liquefaction point extends to the end of segment 0 and at the maximum casting speed of 10 m / min, Has already been extended to the inner arc of the. These casting conditions are also extremely disadvantageous for billet shell deformation or oxide purity.

A two-step zone extending between the two straight lines, namely the straight line (G1) for the arrangement of the deepest liquefaction points and the associated deepest solidification point, or the straight line (G2) for final solidification associated with the casting speed, It starts when the thickness reduction is at the maximum casting speed of 10 m / min at the end of the segment 0 preceding it.

Fig. 3, part 3a (see left half of Fig. 3) shows the final segment Nr. 2 for a maximum casting speed of 10 m / min at segment 0 of length 2m. 14 shows the formation of a different phase of 100 mm thickness by meniscus in die casting with billet thickness reduction continuing from solidification thickness 100 mm to 80 mm to final solidification. Part 3a shows that segment 0 and possible maximum deformation, caused by the bending process of the billet through the five bending points and the straight bending process at the inner arc, are introduced into the billet and the bad conditions leading to the increase of oxide into the meniscus We also clarify that it is introduced into the cast slag.

Fig. 3a shows the reduction speed of 0.833 mm / s and the casting speed of 10 m / min when the casting speed of the billet is reduced from 100 mm to 80 mm, that is, 20% To 1.66 mm / s. This billet thickness reduction speed is a direct measure of the deformation of billet shell about 10.3 mm when entering segment 0 at a casting speed of 5 m / min and about 7.3 mm thick at a casting speed of 10 m / min. This billet deformation resulting from continuous casting is high, and besides the doubling from 0.83 to 1.66 mm / s through an increase in casting speed from 5 to 10 m / min, as expressed by the simplest calculation of 1.66 mm, Transforms with the square function.

These high deformations are also dented by the bending process in segment 0, which is a risk of rupture both inside and outside of the billet shell, especially where steel products are susceptible to rupture.

The present invention is based on the fact that the casting die is installed directly below the casting die to reduce the thickness of the billet. The present invention proposes a method concept and a facility concept for a high-speed continuous casting facility, The quality of the surface and the internal quality of the product.

This problem is solved together with the features presented in claim 1 and in claim 7 of the method. The criterion of the base claim includes the intentional and advantageous forms of the invention. This describes the unexpected resolution of the myriad and complex problems identified and will be described in detail below. The present invention now clarifies and synthesizes the following detailed features:

- minimum facility height between the final solidification and favorable hydraulic-driven, vibrational vertical-diecasting meniscus in the horizontal extent of the billet guide

- Minimized deformation thickness of all deformation in bending deformation and continuous casting deformation in vertical bending facility with concave die casting wide face - Maximum rolling speed of 10m / min in favor of conventional roller diameter and distribution in billet guidance

- mechanical elements for the performance of the billet thickness reduction at the maximum casting speed, for example 10 m / min, in the complete demolition of the superheating phase or in the complete demolition of the penetration site for continuous casting installations, To ensure billet symmetry at the superheat zone or at the pure melt stage

- At segment 0, for example at a maximum casting speed of 10 m / min, at least the dissolving / crystalline 2-phase zone at the end of segment 0 precedes the billet thickness reduction or continuous casting in the center of the billet, The process is presupposed.

- the strain rate of the billet shell at segment 0 up to 1.2 mm / s,

- Bending deformation minimized in segment 1 on a vertical line passing through multiple inflection points in an internal arc independent of continuous casting deformation in segment 0 directly connected to segment 1,

- the forward deformation thickness reduced at the internal equipment radius to the horizon past several forward bending points or reverse bending points, in particular to an average-casting speed of at least 80% of the maximum casting speed at a final cracking of 12 s or 2 m.

Figures 1 and 2 show the distributions according to the invention, the final solidification and the maximum deformation according to the casting speed, of a billet internal deformation with features of the equipment configuration for a casting speed of 5 and 10 m / min, ,

Figure 3 shows the final segment Nr. 2 for a maximum casting speed of 10 m / min at segment 0 of length 2 m. 14 shows the formation of a 100 mm thick different phase by meniscus in die casting with continuous billet thickness reduction from 100 mm to 80 mm, until final solidification, and

4 is an embodiment of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

- (D-5) 5m / min Billet internal deformation during solidification at continuous casting speed

- (D-10) Billet internal deformation during solidification at 10m / min continuous casting speed

- (D-B) Bending deformation to inner billet shell when bending a billet on a vertical line in an internal arc

- (D-R) Reverse bending deformation from horizontally oriented billets to inner billet shells from the inner arc through several associated points

- Continuous Casting Deformation to (D-Gw) Inner Billet Sheath

(D-Ge) = (D-B) + (D-Gw)

- (D-Kr) Critical or critical deformation of inner billet shell

- (1) the distance from the meniscus in relation to the rate of continuous casting, as a deep liquefaction point or a deep point of superheat

- (1.1) When the continuous casting speed is 10 m / min, the distance from the meniscus to the deepest liquefaction point

- (1.2) The distance of the deepest liquefaction point from the meniscus at the continuous casting speed of 5m / min

Phase mixture of about 10 000 cP (similar to honey at 20 ° C) and a 50% crystal ratio at a distance of 8.25 m to 16.6 m from the meniscus at a continuous casting speed of 5 and 10 m / min (Gw-50%

- (2) Maximum deep freezing point or sump edge at m from the continuous casting speed and associated meniscus

- (2.1) When the continuous casting speed is 10 m / min, the distance from the meniscus to the sump edge

- (2.2) When the continuous casting speed is 5 m / min, the distance from the meniscus to the sump edge

- V splitter

- Ta penetration ingot

- Hydraulic driven vertical-diecasting for K-vibration

- As 0 gear segment, segment 0

- Segment 1 as one bending segment

- Segment 2 as two arc segments

- Segment 3 as three arc segments

- 4 reverse bending segments, segment 4

- 5 Segment 5 as a horizontal segment

- 6 As a horizontal segment, segment 6

- 14 As a horizontal segment, segment 14

In FIG. 2 and in FIG. 3B (see the right half of FIG. 3), the invention has been illustrated schematically with reference to the method and apparatus.

Figure 2 shows the distribution, the final solidification and the maximum deformation according to the casting speed according to the invention of a billet internal deformation with features of the equipment configuration for a casting speed of 5 and 10 m / min through the billet induction extension.

The continuous casting method is inventive, minimizing the thickness of the billet deformation past the billet induction, and all deformation modes occur irrespective of the others arranged behind. Deformation curves (D-5) and (D-10) proceed below the critical point and thereby the limiting strain (D-Kr). The outgoing deformation curve clarified that the accumulation of deformation occurring through continuous casting and bending is avoided through the fact that: (DB) of the billet in the connected segment 1 passing through the billet thickness reduction (D-Gw) and, for example, five bending points, at the vertical segment 0, which in the actual example is 3 m long .

Further, in FIG. 2, the penetration zone inside the billet forming approximately 10% of the coagulation time at 25 ° C overheating of the steel in the superficial liquefaction point (1.1) or overheating zone to the distributor, It can be deduced that it reaches up to 3m below the curse or extends to a depth of 2m by the segment 0. Through which it can be symmetrically raised and elevated for the billet solidification in the oxide-free and vertically arranged pure melt phase, while at the same time determining under the deepest liquefaction point, in which the two-phase zone fully realizes the interior of the billet And macro-liquefaction and medium-scale liquefaction suppression through a casting process that passes through segments 0 to 1 m shots.

The two-phase zone is elongated by a straight line G1 indicating the position of the deepest layer of the liquefaction point and a straight line G2 indicating the state of the liquid pool end according to the casting speed. The crystal / dissolve 2-phase zone starts at 1.5 m (liquefaction point 1.2) to 0.5 m below the meniscus at a speed of 5 m / min VG after the billet enters segment 0, and about 15.1 m 2)). For a casting speed of 10 m / min, the two-phase zone starts at about 3 m (1.1) and ends at about 30.2 m (2.1) with a sump edge (see FIG.

A continuous casting process with a complete two-phase zone between the billet shrinkage or billet shell is extended beyond 1 m at a VG of 10 m / min past a 2.5 m of a shot of segment 0 at a casting speed VG of 5 m / min. In both cases, forced convection of the two-phase zone is achieved, which ensures an improvement in the quality of the billet interior.

The reverse bending of the billet from the inner radius - for example, beyond 4 m beyond a number of reverse bending points, ie past five target points - to the horizon ensures firm smooth deformation (DR) and, at the same time, In order to avoid adverse effects through this billet transformation, the example according to Fig. 3 is preempted in segment 4 of length 2 m.

Further, part 3b shown in Fig. 3 can be pointed out. (D-Gw) from 100 to 80 m, along with a deformation rate of 1.11 mm / s at a casting speed of 10 m / min, and a VG of 5 m / min and at a strain rate of 0.55 mm / s. This deformation rate was essentially reduced compared to segment 0 of 2 m length and 1.66 mm / s at 10 m / min casting speed. Whereby the strain rate lies below the already known threshold value of 1.25 mm / s.

The advantage achieved by the present invention can be found in securing a continuous casting method for thin slabs of initial solidification thickness, mainly between 60-120 mm, with direct casting steps under vertical-die casting in vertically aligned segment 0. Vertical-Die Casting According to FIG. 4, the melt casting leads the steel into a vertical die cast (Ta) in the distributor (V). Vertical-die casting should have exhibited a concave wide faceplate with the advantage that the following facts

- Exact vibration and vibration during casting Type, frequency, variety of administration

- Lubricate the same type of slag over the entire billet

- Quiet bass level exercise

- Heat conduction of the same type of die cascade

- Continuous continuous casting in die casting and billet induction

- High casting safety while avoiding cracks.

To be clear, it had to be hydropower driven.

The billet guide may be concavely installed at a maximum speed of 2 x 12 mm in order to direct the billet directly at the high-speed casting speed and certainly to the billet guide. This can be realized, for example, with a concavely executed billet guide roller. Otherwise the scale of deflection out of the die casting outlet or concavely out from the initial billet guide roller to the final roller of the billet guide shall be non-constant and shall be at least always sufficient to the function of at least sufficient Or a sufficient arc should be removed.

Segment 0 must be vertically aligned and must be installed independently to reduce billet thickness. It must have a minimum length and be capable of calculating the velocity at the casting thickness reduction of less than 1.25 mm / s at the billet at the maximum casting speed, while at the same time permitting complete dissolution of the superheat and crystallization / It should exhibit a minimum length which clarifies another possible disassembly of the crystallization step in the zone and the inhibition of macro liquefaction and central liquefaction. In this example, segment 0 indicates a length of 3 m.

In order to keep the billet shell deformation thickness small and to prevent overburdening with the preceding continuous casting deformation, which immediately follows the continuous casting process in segment 1, i.e. segment 0, for example in segment 1, five Bending of billets with two-phase mixing between billet shells via bending points is preempted according to the invention.

For example, according to the geometry of the facility height and geometry of about 8 m, the final solidification at a casting speed VG 5 or 10 m / min in segment 4, which is about 12 m away from the meniscus, ends at a distance of about 15 or 30 m from the meniscus Reverse bending occurs at the horizon via five related points that occur much earlier. 36 s or 108 s are placed between the reverse bending and the associated deformation of the inner billet shell and the ultimate coagulation which is extremely sensitive to deformation, together with the failure of final solidification at the sump edge and the associated error in the core of the slab through reverse bending Lt; / RTI >

4, for the production of a maximum of 3.0 mio tpa in cross-section for a billet thickness of 100 mm at the outlet of a vertical-casting die of hydraulic drive showing a solidification thickness of 80 mm and a maximum casting speed of 10 m / min, Continuous casting equipment is composed as follows.

- a 1.2 m long vertical-casting die with a maximum thickness of 180 mm at the center of the meniscus and a minimum thickness of 100 mm at the center and a thickness of 100 mm at the minimum part of the casting die

- Vertical segment 0 installed with a 3 m long gear segment to reduce billet thickness to 80 mm

- Segment 1 with five bending points and an inner radius of 4 m

- Segments 2 and 3 in the internal arc

- Segment 4 with five related points and

- segment 5 to 13 in the horizontal section of the billet induction.

The entire continuous casting plant has an alchemical length of about 30 m, of which about 4 m is arranged vertically (K and 0), about 8 m (segment 1, 2, 3, 4) (Segments 5 through 13). At a casting speed of up to 10 m / min, the deepest liquefaction point (1.1) of about 2 m reaches a segment 0 of length 3 m, whereby the symmetrical distribution of the oxide remaining in the steel is also achieved by the dissolution of crystals And the inhibition of core liquefaction in billets. The two-phase complex at a 50% crystal ratio ((Gw-50%)) at a distance of about 16.5 m from the meniscus is based on a viscosity of 10 000 cP (equivalent to honey at 20 ° C). In addition, the final solidification (2.1) in the final segment (13) is executed far from the reverse bending of the segment (4).

Between the reverse bending and the final solidification at the sump edge, there is a barrier free closure time of about 108 s ensuring good core solidification.

Claims (16)

A method for the production of sheet metal slabs in a continuous casting plant, - Billet shrinkage, referred to as continuous casting, with the first segment (0), which proceeds vertically in the billet induction immediately below the casting die, is exclusively pre-cast - Segment (1) arranged just below the first segment (0) has multiple venting points or pre-bends the billet in the internal arc Characterized in that the billet is reverse bent to the horizon via several reverse bends prior to final solidification. 2. The method of claim 1 wherein a vertical casting die is used having a concave profile running symmetrically on the horizontal line of the wide face of the casting die. 3. A method as claimed in claim 1 or 2, characterized in that the concave profile from the beginning of the casting die (meniscus range) to the end of the casting die is fully accommodated by a functional progression. 3. A method according to claim 1 or 2, characterized in that the concave profile from the beginning of the casting die (meniscus range) to the end of the casting die is retrofitted with a residual concavity of up to 10% Way. 5. A method according to claim 4, wherein the remaining concave surface in the billet induction is retrofitted with a concave or crowning of the slab of at least +0 mm. The method according to any one of claims 1 to 5, wherein the length of the vertically traveling segment (0) is such that at the maximum casting speed, the pure melt point or the deepest deep liquifying point is aligned primarily with the bottom and the end of the segment (0), but does not exceed 1.25 mm / s in the billet when the billet is shrunk. A continuous casting installation for carrying out the method of any one of claims 1 to 6, - a vertically traveling segment (0) is provided for billet thickness reduction between 40 and 10 mm, The following segment (1) presents at least three bending points and the radius of the inner arc is located at 6 to 3 m - forming at least three relative points from the inner arc to the horizon for the reverse bending of the billet and the final reverse bending point at 80% of the maximum casting speed indicating a distance of at least 2 m from the vessel end. 8. A continuous casting installation according to claim 7, characterized in that the vertical segment (0) represents a length of at least 2 m. The continuous casting installation according to claim 7 or 8, wherein the height of the facility between the meniscus and the lower edge of the billet in the horizontal billet induction is 10 m or more. 10. A continuous casting installation according to any one of claims 7 to 9, characterized in that the die casting in the range of the melting surface exhibits a thickness between 160 and 70 mm. 11. A method according to any one of claims 7 to 10, wherein the wide face of the vertical die casting has a horizontal, concave and symmetrical profile with an opening at the center of the wide face of a meniscus range of up to 40 mm for each wide face The continuous casting equipment. The continuous casting installation according to any one of claims 7 to 11, characterized in that the at least 40 mm concave profile for each wide face in the meniscus part of the die cast is formed completely retroactively to the end of the die casting at the latest. 11. The method according to any one of claims 7 to 11, characterized in that a convex profile with a maximum of 40 mm for each wide face in the meniscus part of the die cast is retroactively formed with a residual convexity of maximum 12 mm for each wide face to the end of the die cast at the latest Wherein the continuous casting equipment comprises: The continuous casting according to any one of claims 7 to 11 and 13, characterized in that at the die casting outlet in the billet guide, the trapezoidal surface is retroactively formed with a minimum of concave or at least + 0 mm crowning of the slab. Casting equipment. 15. Continuous casting equipment according to any one of claims 7 to 14, characterized in that the continuous casting equipment and billet guidance is at least 10 m. 16. A continuous casting installation according to any one of claims 7 to 15 characterized by a continuous casting speed of up to 10 m / min.