MXPA98002042A - Moldes optimized between yes of the continuous colada milles and the immersion filling for ac planta disbasts - Google Patents

Abstract

The present invention relates to an oscillating mold for continuous casting of flat slabs, the oscillating mold comprising wide side plates and narrow side plates that move freely in relation to the wide side plates, counting the wide side plates and the narrow side plates with a pouring zone and defining a mold outlet, the oscillating mold further comprising a dipping filling located between the wide side plates and the narrow side plates, the dip filling having an internal flow cross section, a width and a wall thickness, an outer cross section, with a cross-sectional format and with a thickness extending in a direction parallel to the wide side plates and with a thickness extending perpendicularly to the thickness direction, defining the side plates wide a symmetrical wash with respect to the center with With a recess shape configured in such a way that the distance between the wide side wall in the casting recess is at least partially reduced in a direction towards the mold exit and so that it is in correspondence with the level zone. of casting and at least this along the immersion filling towards the format of the outer cross section of the immersion filler, the wide side plates having adjacent the casting recess in a linear and flat manner through the symmetrically centered shell height and perpendicularly concave to the width of the mold, wherein the concave shape along the wide side plates reaches a maximum opening of 4% of the thickness of the narrow side plates and wherein the opening of the shape of the plug in the level area of pouring reaches a maximum of 70% of the thickness of the dipping filling or a maximum of 140% of the half of the thickness of the dipping filling.

Description

Optimized molds of continuous casting and immersion filling for steel slabs FIELD OF THE INVENTION The invention relates to an oscillating mold for continuous casting of flat slabs, preferably made of steel with dip filling and casting powder keep going. DESCRIPTION OF THE PREVIOUS TECHNIQUE The continuous casting is carried out especially in formats of the thickness range between 20 and 250 mm, preferably 40-150 mm (thin flat slabs), and of the width format between 500 and 3,300 mm, preferably 500 - 1,800 mm, with casting speeds of 10 m / min maximum. The thin flat slabs or flat slabs opened by means of a known level tap or bucket so far can be classified in the following groups for advantages and disadvantages. DE 887 990 discloses a shrinkage mold with a rectangular mold outlet, which consists of a mold and does not have any narrow side independent of the wide sides. For different casting speeds and steel grades, this mold does not allow the taper of the narrow sides to be adapted to the extent of shrinking of the bar in the direction of the width over the height of the mold, or to melt different bar widths.

There is also the danger that the continuous casing will grip, which leads to the tearing of the continuous casing in the demoulding. DE 34 00 220 discloses a shrinkage mold with walls in the narrow and wide sides, in which a parallel zone corresponding at least to the thickness of the cast strip is arranged on the side of the recessed pouring zone. of the thin flat slab. With this mold, the drawbacks of the mold according to the above-mentioned patent DE 887 990 are eliminated. In JOS patent 58-86906 a shell is described which is concave independently of the filling mold by immersion and which at the outlet of the shell presents a residual concavity. At the same time, the retraction of the concavity over the length of the shell is greater than the rebate of the flat slab over the width of the shell, in such a way that the conicity of the narrow sides is negative or the width of the rod in the shell. The exit of the shell is greater than in the area of the pouring level. Furthermore, this solution does not guarantee a uniform formation of slag over the width of the bar, since the active bar thickness at the pouring level is not uniform in relation to the function of the casting powder. This irregular slag formation is also recognized in DE 36 27 991.

DE 41 31 829 discloses a thin flat slab with 4 plates that is concave in the region of the smallest flat slab width. This opening in the pour level zone and in the center of the rough slab is 12 mm per 1,000 m maximum flat slab width. This chill mold has the drawback that in the area between the wide side of the shell and the dip tube, which is very narrow (max 2 x 0.25 mm thickness) with respect to the area outside the dip tube. flat roughing + 12 mm), there is a lack of casting slag as well as a lack of fresh melt, which results in a high heat current and retraction effect as well as overcooling and the formation of bridges between the Pouring shirt and immersion filler. These disadvantages result in a high predisposition to longitudinal cracks in the surface of the rough slab in the area around the center of the slab. DE 44 03 045 and DE 44 03 050 describe concave mold molds but make no mention of a dependence between the concave mold shell and the inner and outer immersion filling mold. This lack of optimization of the molds together leads to disturbances of the heat flux over the width and height of the mold as well as the flow of steel at and below the pouring level., which in turn carries the risk of the formation of longitudinal cracks. In the European patent application 0 109 357 Al there is no consideration regarding the choice of the concave shell mold, the immersion filler or the dip tube. In addition, here it is a question of coquillas for the casting of aluminum with the application of electromagnetic fields, that is, the bar, in the formation of the casing, has no contact with the shell. Likewise, no casting powder is used and the mold does not oscillate. In addition, it does not melt continuously, but melts into a kind of tilted ingot casting mold. Along with these thin slabs of thin slabs, it would be necessary to go into detail in the classic slabs with the rectangular format, for example, 200 x 200 mm. Apart from the fact that the casting speed is only 2 m / min maximum and that the heat current, and with it the retraction, is only approx. 1 MW / m and 1%, respectively, this standardized shell system, despite a relatively thick slag film between the casing and the shell, eg, 1 - 2 mm thick, has the following faults: * an irregular slag formation on the width of the bar in the area of the dip tube, * an overcooling of the steel in the area of the dip tube with respect to the area next to the dip tube, * an impediment to retraction in the horizontal direction by the parallel shape of the coguilla and this especially for the wide formats of slabs. SUMMARY OF THE INVENTION The object of the invention is to find a mold of shell that for a casting of immersion filler defined with respect to * the performance of the casting, * to the inner and outer mold, * to the cross section of flow, * a the exit holes in dimension and arrangement and * to the wall thicknesses (casting time, number of castings in the maximum sequential casting) is adapted to the following requirements: * uniform formation of slag over the width of the flat slab, * uniform and restful movement of the bath, * retraction with reduced friction and uniform wear of the casting on the width of the rough slab, * casting of different widths with a mold (large range of adaptation), * adjustment of different conical positions of the narrow sides by means of piloting, and also regulation. The objective is achieved by the attributes of the claims, which, of course, are clear to the specialist. The lens solution is independent of the shell type, such as, for example, vertical molds, deviated from the vertical or arc. BRIEF DESCRIPTION OF THE DRAWINGS The figures serve to clarify the following description by way of example of the invention. They show: Fig. 1 a plan view of the shrinkage mold with two variants of immersion filling tube, Fig. 2 a side view of the re-polishing mold with three different shapes of recess, Fig. 3 a view in the plant of the shrinking mold with two exit shapes in the mold outlet, FIG. 4 shows a side view of the shrinkage mold with three different shapes of rechupe and two variants of immersion filler. DETAILED DESCRIPTION OF THE INVENTION The tests carried out for the elaboration of the invention and the accumulated laundry experiences have shown that for a safe casting against interruptions and for the sequential casting during a desired long casting time, eg, 24 hours maximum and a maximum casting speed of 10 m / min. , for the production of flawless bar surfaces, the mold of the mold in combination with the arrangement / configuration (mold) of immersion filler is of essential importance for the desired casting performances. In Figs. 1 to 4 the invention with its attributes is described by way of example. The wide sides 1 of the mold have through the whole shell height 3 a concave mold 1.1 linear or flat, symmetrical with respect to the middle axis 2. This concave, linear mold extends over the region of the lateral displacement in width up to the edge 5.1 of the sprue 5 in the pouring zone 6 and the upper edge of the shell 7. This concave and flat hole of the shell 1.2, which corresponds to a rhombus, should correspond in comparison with the rectangular shell approximately a maximum of 4% of the thickness of the narrow sides 1.3 or of the thickness of the casting in the narrow lateral zone.

In order to guarantee optimal width offset and taper adjustment, the wide sides 1 should be approximated to the narrow sides 1.3 hydraulically adjusted in position and force. The form 5.2 of the plug 5 at the pouring level corresponds to the mold 8.1 of the dipping filling 8 and has an orifice 5.3 preferably of 140% of the half of the thickness of the dipping filling 8.2 and 70% of the thickness of the dipping filling 8.2.1. The immersion filling itself, conditioned by the maximum casting time (sequential casting, eg, 24 hours) and the casting production in Tn / min, eg 5 Tn / min desired and the optimum circulation speed , eg 1 m / sec in relation to these values, in the dip-filler holes 8.3 with the orifice cross-section 8.3.1, it has a desired interior flow cross-section 8.4, eg 9,000 mm, a desired immersion filler wall thickness 8.5, eg 30 mm and an orifice cross-section 8.3.1, eg 7,000 mm. The immersion filling mold, basically fixed by the desired casting production and the maximum casting time, determines the recess mold 5 both in the pouring zone 6 and also below the pouring level. Preferably, the plug hole 5.3 in the pouring zone should correspond approximately to half the thickness of the dip filler 8.2, and the width of the recesses 5.4 approximately to the width of the immersion filler 8.6 so that the casting powder 9 forms a uniform thickness of slag 10 on the level of the bath and with it a uniform film of slag 11 between the jacket the bar and the wide side of the shell 1. As a maximum, the hole in the gap in the level of casting should reach, depending on the wide side, 70% of the total thickness of the dip filler 8.3.1, and that the specific thermal conductivity of the refractory material (based on alumina-graphite) is about 7 - 10 W / ° K xm compared to the steel, about 50, of the slag, of approx. 1 and Cu, about 360 / ° K, and this relatively low conductivity leads to strong supercoolings of the bar, especially in the case of a rectangular shell. The orifice of the shell through a plug, conditioned by the reduced conductivity of the material of the dipping filler, opposes this supercooling between the dipping filler 8 and the shell wall 1 and compensates it in the case of an orifice rechupe 5.3 >; 50% of the thickness of immersion tube. This form of recess 5.2 which is superimposed on the concave, linear and flat mold of the wide side in the center of the wide sides of the pouring zone 6 can be retracted in an alternative of three modes which are essentially determined by the 5.2 dipping filling mold below the level of the bath. The retraction of the recess in the concave, flat mold of the wide sides 1.1 is described by the wrapping curve 13. Thus the recess can be retracted over a part of the shell height 13.1 - preferably 75% - for a total shell height 3 , eg, 1200 mm. For shorter shells or delicate steel grades it is also possible to retract more gently the shape of the plug. This can be carried out by causing the envelope curve 13.2 to reach the total shell height 3 or even to exceed the shell outlet 14, that is, because at the shell outlet still a part of the plug 15 overlaps, symmetrically to the center, to the concave, linear mold of the wide side 1.1. The bar, in the case of the retraction of the recess 5 within the height of the shell 3 can be conducted through the surrounding curve 13.1 or 13.2 with its mold of convex cross section, linear, symmetrical with respect to the center 1.1 to the end of the bar guide 16 or in the laminator, or it can also be formed in the area of the bar guide 16 in a rectangular format.

In the case of a convex bar format at the cusp outlet 4, which has a residual bulge corresponding to the rest of the recess 15, the format can be partially maintained until the end of the bar guide or it can also be redirected to a rectangular mold . This type of mold according to the invention with its specific shape of recess attached to the conditions optimized with respect to * the circulation, * the movement of the bath, * the guide of the slag, * the heat flow and * the retraction behavior contributes a centering of the band in the mold and in the guide of the bar and with it a high safety of casting (avoidance of interruptions) and this at particularly high speeds of casting up to 10 m / min. These considerably complex processes in the casting of thin slabs and slabs, in particular at high casting speeds, are taken into account by the attributes described in the claims. The invention, with respect to the state of the art both in the casting of thin slabs as well as in the slab casting leads to the following advantages of specific attributes such as: the attribute "linear concave mold and wide side plane" leads * to a shrinkage of reduced friction of the bar jacket in the horizontal direction, * to a maximum range of width adjustment by means of the minimum shrink mold independently of the total bar width (for example 500 - 2,000 mm). * to the adjustment of width also during casting, * to the piloting of the conicity or regulation of the narrow sides during the casting, * to surfaces of slabs without longitudinal cracks. The "rechupe" attribute leads * to the free choice of the immersion filling mold with respect to the maximum casting production, Tn / min circulation speeds m / s through * cross sections of circulation in the immersion filling and in the holes of the immersion filler pouring time / maximum sequential casting (eg 24 hours) by the free choice of the wall thicknesses of the immersion filler (30 mm for 1 mm / h of slag wear), uniform movement of the level of the bath, suppression of turbulences, uniform temperature gradients in the bath level from the center of the shell to the bar sleeve over the entire width of the shell, no risk of bridging between the bar jacket and the filling wall of immersion, uniform melting of slags over the width of the level of the bath, uniform formation of the slag film between the bar jacket and the plates of shell of the wide sides, densified d uniform heat flow over the width of the mold, uniform shrinkage behavior of the bar sleeve over the width of the mold, especially in the horizontal direction, good surface of the rough slab and without fissures even in steels with predisposition to fissures longitudinal, such as, for example, peritectic steels, centering of the bar in the shell and the bar guide, * high. casting safety or reduced interruption rates, * possibility of producing a symmetrical concave slab with respect to the center.

Claims (15)

1. NOVELTY OF THE INVENTION Having described the.
2. The above invention is considered as a novelty, and therefore, the content of the following claims is claimed as property: CLAIMS 1.
3. Oscillating shell for continuous casting of flat slabs, preferably steel with dipping filling and continuous casting powder containing the following elements: * an immersion filler (8) with internal flow cross section (8.
4. 4), thicknesses of wall (8.
5. 5), - exit cross section (8.3.1) and outer cross section format (8.1) with a width (8.
6. 6) and a thickness (8.2.1) * narrow linear sides (1.3) freely displaceable throughout the length of the mold on the concave mold (1.1), symmetrical with respect to the center, of the wide side plates (1), * recesses (5) symmetrical with respect to the center incorporated additionally in the wide sides corresponding at least in the area of pouring level (6) to the cross-section mold (8.1) of immersion filler (8) and which are at least partially retracted in the direction of the mold outlet. Device according to claim 1, characterized in that the concave, linear or flat area (1.1) on the wide side plates (1) reaches a maximum opening (1.2) of 4% of the thickness of the narrow side (1.3). Device according to claim 1 or 2, characterized in that the plug (5), at least in the pouring zone (6), follows the external shape of the dip-pad (8.1). Device according to claims 1 to 3, characterized in that the hole (5.3) of the plug in the pouring zone (6) reaches a maximum of 70% of the thickness of the dip filler (8.2.1) or at most to 140% of half the thickness of the immersion filler (8.2). Device according to claims 1 to 4, characterized in that the mold of the plug (5.2) in the shell is fully retracted (13.1 and 13.2) and the shell in the shell outlet (14) has the concave, linear mold (1.1) . Device according to claims 1 to 5, characterized in that the bar is maintained, at least partially, with a convex, symmetrical and linear cross section (1.1) in the bar guide (16).
7. 7. Device according to claims 1 to 5, characterized in that the bar with convex, symmetrical and linear cross section in the bar guide (16) is transformed into a rectangular format.
8. Device according to claims 1 to 4, characterized in that the mold of the plug (5.2) in the shell is retracted only partially (13.3) to the shell outlet (14) and the rod, together with the convex, linear mold (1.1). ), also has a symmetrical bulge with respect to the middle axis that adapts to the remaining plug mold (15).
9. Device according to claims 1 to 4 and 8, characterized in that the bar is held, at least partially, with a convex cross section (15), symmetrical with respect to the center in the bar guide (16).
10. Device according to claims 1 to 4 as well as 8 and 9, characterized in that the bar with cross section (15) convex, symmetrical with respect to the center in the bar guide (16) is transformed into a rectangular format.
11. Device according to claims 1 to 10, characterized in that the narrow sides (1.3) and with them the casting width adjustment zone can be brought and reach at least up to the transition (5.1) between the concave, linear mold of the Wide sides and the rechupe (5).
12. 12. Device according to claims 1 to 11, characterized in that the recess (5) has a minimum width (5.4) of 500 mm.
13. 13. Device according to claims 1 to 12, characterized in that the wide-sided mold plates (1) are inserted in the narrow sides (1.3), regulated in position and force hydraulically.
14. 14. Device according to claims 1 to 13, characterized in that the immersion filler (8) has an internal flow cross section (8.4) up to 20,000 mm, preferably about 9,000 mm, a thickness of immersion filler wall (8.5) of 20 mm to 40 mm, preferably 30 mm. mm, as well as in the immersion fill outlet a total cross section (8.3.1) up to 15,000 mm, preferably about 7,000 mm.
15. 15. Device according to claims 1 to 14, characterized in that the immersion filler orifice or immersion filler holes (8.3) are optimized in relation to the production of prefixable casting in such a manner as in the immersion filler hole (s) ( 8.3) a speed of circulation is established up to 2 m / sec, preferably 1 m / sec approximately.