MXPA99004054A - An ingot for continuous smelting of liquefied metal, particulary to form steel cantonments of square or rectangular section - Google Patents

Abstract

Un conducto de fundición (2) de sección rectangular de una lingotera (1),par al fundición continua del metal de fundición,es dividido en dos porciones (8,9);y de la primera porción (8) tiene una sección de variable interna, porque tiene rebordes internos (5) con unos radios de curvatura gradualmente decrecientes en la dirección de flujo del metal de fundición a lo largo del conducto (2);la segunda porción (9) es consecutiva con la primera porción (8) y tiene una sección interna constante con extremos internos redondeados de un radioóptimo predeterminado de curvatura por operaciones subsecuentes de laminado. El diseño de la primera porción (8) del conducto de fundición (2) previene el metal,cuando es enfriado y se contrae a través del conducto, del desprendimiento de las paredes, y en particular de los rebordes (5) del molde (1) asípermite un incremento en la velocidad de fundición sin caída en la calidad del proceso.

Description

LINGOTERA FOR CONTINUOUS CASTING OF LIQUEFIED METAL, PARTICULARLY TO FORM SECRET STEEL ACANONMENTS SQUARE OR RECTANGULAR The present invention relates to an ingot mold for continuous casting of liquefied metal, particularly for forming square or rectangular section steel billets. The billets or ingots can be formed of liquefied metal, particularly steel, by continuous casting of liquefied metal from a mold in the form (ingot mold) followed immediately by lumination (so-called "casting and direct rolling" technique). While it equally allows for high output speeds and good quality products, this technique currently has severe disadvantages - mainly due to the processes by which the liquefied material is cooled and solidified in the mold - which limits the maximum output speed obtainable and the range of products that can be produced from the same mold. That is, rapid casting in excess in a continuous mold - through the liquefied material and initiates solidification - known to result in the formation of defects in the finished product. More specifically, cooling, which occurs through the liquefied material producing heat to the walls of the mold, is only effective in its entirety if the material remains in contact with the walls, so a solid metal surface layer (so-called "crusts"). ) is formed and gradually increased as the material that travels through the mold. As it is solidified, however, the contractions of material are distanced from the walls, particularly the internal flanges of the mold, so that air pockets are formed between the metal crust and the mold wall, this reduces the amount of heat emitted. , and decrease the speed of the solidification process. The metal crust (solid layer) therefore continues to grow, except in corners where insufficient heat is reduced, this results in only partial solidification of the cast metal and the formation of defects in the finished product. This also increases the possibility of forming cracks in the flanges, due to the unwanted tension in the metal crust as it is spaced between the walls of the mold. For short, the resulting cantonment is of poor proportional strength, is highly susceptible to the formation of longitudinal cracks along the ridges, and has a very uneven crusting temperature, all of which create problems at the subsequent lamination stage. invariably and odd to the quality of the finished product.

To overcome these drawbacks, a relatively low casting speed is maintained to allow the material to be cooled as uniformly as possible. Also, reduce the radius of curvature of the known internal corners of the mold to reduce the formation of air pockets, again providing casting speed is not very high. When the casting is only of one type of material, the isolation of the metal crust from the mold walls can be reduced by improving the geometry of the mold, for example using appropriately tapered molds. This solution, however, can not be applied to molds to produce materials of different characteristics (for example different types of steel). Finally, some known molds have a particular, for example concave walls, section for the passage of molten metal, while reducing the insulation problems, however, this type of mold also fails to provide for the increased casting speed on of and previous to certain limits. It is an object of the present invention to provide an ingot mold for continuous casting of metal materials, designed to overcome the disadvantages mentioned in the above typically associated with the known molds. In. particularIt is an object of the invention to provide an ingot mold which allows effective cooling of the molten metal at all points and along the entire length of the mold, to prevent isolation of the metal from the walls, even from the flanges of the mold, and to allow high-speed casting of products that exceed the permitted quality of immediate lamination. According to the present invention, an ingot mold is provided for continuous casting of molten metal, in particular, to form square or rectangular section steel billets, comprising a longitudinally elongated casting conduit through which the molten metal flows and is cooled; the casting duct has a substantially rectangular cross-section, being defined by a first and second pair of substantially parallel side-by-side walls; the first and second pair of walls are substantially perpendicular to one another, and define four internal ridges; characterized in that the casting conduit comprises at least a first portion having rounded internal ridges and an internal section of a variation gradually from a respective longitudinal first end, in which the cast metal is fed, towards a respective second longitudinal end opposite to the First; the first variation in section of the at least one first portion being determined by a continuous correspondence, the gradual graduation in the radius of curvature of the rounded internal rim; the radius of curvature descends from a maximum value to the first end, to a minimum value to the second end. More particularly, the sectional variation of at least a first portion of the casting duct is such as to reproduce a thermal contraction of molten metal as it travels through a first portion. The particular design of the ingot mold according to the present invention provides the molten metal effectively cooled to all surface points, including to the inner flanges, and along the entire length of the mold. The material, in fact, remains in contact with the walls, even the shoulders, of the mold at all times, by virtue of the particular internal section of the variable section portion, which at the point of fact reproduces the cooling pattern of the material as it is cooled and solidified. The metal is then prevented from separating from the walls, even from the flanges of the mold, without the need to maintain an excessively low casting speed. The internal cooling of the mold according to the invention is thus effective when it allows immediate direct lamination of the product emitted from the conduit with the need for any immediate process, by virtue of the material having the required characteristics (in particular, without internal attention to the flanges, and even a temperature crust) in addition, the same mold can be used for different materials, for example to produce different types of steel, while at the same time guarantee high quality products and maintains a high production speed. A non-limiting embodiment of the present invention should be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic perspective view of an ingot mold for continuous casting of molten metal in accordance with the present invention; Figure 2 shows a schematic plan view of the molten metal of internal section of the mold of Figure 1 in Figure 1 and 2, in which the parts are deliberately shown far outside the portion to highlight the main features of the invention, the number indicates as a totality of an ingot mold for continuous function of the cast metal, for example steel, in the form of cantonment of rectangular section. The mold 1 comprises a longitudinally elongated casting duct 2 through which the cast metal flows; the duct 2 has a substantially rectangular cross-section, and is defined by a first pair 3 and a second pair 4 substantially in parallel, the side-by-side walls of predetermined size; and pairs of walls 3 and 4 are perpendicular to one another and define 4 flanges 5.

In the non-limiting examples shown in Figure 1, the duct 2 is curved, by walls 3 being flat and walls 4 having a predetermined curvature, but may obviously be of a longitudinal shape different from that described, for example, rectilinear. In either case, the conduit 2 extends substantially in a predetermined direction parallel to the pair of flat walls 3. According to the present invention, the conduit 2 comprises, from a respective longitudinal first end 7 to which the molten metal a first portion 8 with a variable internal section is fed; and a second consecutive portion 9 with a constant internal section and determination to a second end 10 of the conduit 2 to which the molten metal is fed outside. The first portion 8 extends longitudinally by a predetermined increased length 'above a second respective end 11 defined by an intermediate section of the conduit 2, which is next to the section to which the molten metal is fed out of the first portion. 8, and the section to which the molten metal is fed into the second portion 9. The flanges 5 defined by walls 3 and 4 are internally rounded along the entire length of the conduit 2; the bend radius of the flanges 5 gradually varies along the first portion 8, continuously decreases from a maximum value Ri at the end 7 to a minimum value R2 to the opposite end 11, and maintains a constant value of R2 throughout of the full length of the second portion 9; and the selected minimum value R2 of the bend radius of the flanges 5 is the best value by which subsequently the metal roll emits from the casting conduit 2. The gradual variation in the radius of curvature of the flanges 5 along the first portion 8 produces a corresponding gradual variation in the section of the portion 8. More specifically, the variation in the sections obtained by means of the funnel-shaped portions 12 to the 4 rims 5 of the portion 8: the four portions 12 funnel-shaped project walls 3 and 4 transversely further, extended longitudinally from end 7 to end 11 of portion 8, and taper towards end 11 of portion 8, which although defined by pairs of parallel walls 3 and 4 , accordingly it has, as established, a longitudinally variable inner section in descent in the area from end 7 to end 11. At end 11, portion 8 has a section rectangular cross section without projections and coincident with the constant section of the second portion 9. The variation in the section of the first portion 8 is as reproduced from the thermal contraction of the metal as it was fed and cooled the elongated portion 8. For which purpose, in a preferred embodiment of the invention, the variations in section of the first portion 8 and the corresponding variation in the radius of curvature of the internal ridges 5 are not aligned variations. Also, the longitudinal extension of the first portion 8 of variable section is roughly preferably equal to that of the second portion 9 of constant section. According to the preferred embodiment, the longitudinal extension of the first portion 8 is less than, for example 95% of the longitudinal extent of the second portion 9. In a typical embodiment, merely the manner of an example not limited, the first portion 8 and the second portion 9 have respective lengths L? = 450 mm and L2 = 600 mm; where the lengths, all similar to other distances indicated in Next, they are measured along a parallel axis of the flat walls 3 (as opposed to a longitudinal axis of conduit 2, which, as established, can be employed as shown in Figure 1.) As such, the radius of curvature of the flanges 5 to the inlet end 7 of the cast metal is R? = llmm; in an intermediate section 13 (Figure 1) of the portion 8 at a distance from the end 7 (again measured along the parallel axes of the flat walls 3), the radius of curvature assumes a value of 10.4 mm; intermediate and, at the end 11 of the portion 8 (which is at a distance L? = 450mm from the end 7, or at a distance L4 = 210mm from the intermediate section 13), the radii of curvature of value R2 = 10mm, minimum equal, which are then maintained along the total length of the second portion 9 above the exit end 10. of the conduit 2. The radius between the variation in the radii of curvature and the distance from the entrance end 7 of the melting metal of portion 8 is therefore not constant along portion 8, but decreases next to the distance from end 7: in the example shown, in which intermediate section 13 divides portion 8 within a first portion 14 and a second portion 15 of the different lengths, the radius approaches 0.00025 of the portion 14 along the length L3 = 240mm (where the radii of curvature decrease from 11mm to 10.4mm), and approaches 0.002 throughout portion 1 5 of the length L? = 210 mm (where the radii of curvature also decrease from 10.4 mm to 10 mm). In this exemplary embodiment, the variations in the radii of curvature of the ends 5, when opposite a linear function or a distance from the inlet end 7 of the molten metal of the conduit 2, is obviously such as to reproduce the variations in the section of the molten metal when cooled (is therefore a function of the thermal contraction of the metal) The dimensions of the wall pairs 3 and 4 can obviously be selected to obtain finished products of the predetermined size. In particular, to form square section cantonments, the ratio between the amplitude of the flat walls 3 and the width of the curvature walls 4 is preferably 1: 1.01. Obviously, the changes can be made in the ingot mold as described in the foregoing, however, without departing from the scope of the claims that accompany it.

Claims (11)

1. An ingot mold for continuous casting of cast metal, in particular, to form steel cantonments of rectangular and square section, comprising a longitudinally elongated casting conduit through which the cast metal flows and cools; the casting duct has a substantially rectangular cross-section, and is defined by a first and a second pair of substantially parallel side-by-side walls; the first and second pair of walls being substantially perpendicular to one another and defining four internal ridges; characterized in that the casting conduit comprises at least a first portion having rounded internal ends and an internal section that varies gradually from a respective longitudinal first end, although the casting metal is fed, towards a second respective longitudinal end opposite the first; the variation in the section of at least one first portion is determined by corresponding continuity, the gradual variation in the radii of curvature of the flanged inner flanges; the radii of curvature decrease from a maximum value Ri to the first end, to a minimum value R2 to the second end.

2. The mold according to claim 1, characterized in that the variation in the section of at least the first portion of the casting duct is such as to produce a thermal contraction of the casting metal when it travels through, and partially solidified, at least one first portion.

3. The mold according to claim 1 or 2, characterized in that the variation in the section of the at least one first portion and the corresponding variation in the radii of curvature of the flanged inner flanges are non-linear functions of the distance from the first end of the mold. at least a first portion.

4. The mold according to one of claims 1 to 3, characterized in that the variation in the section of the at least one first portion is obtained by means of four funnel-shaped portions with which at least a first portion is provided, and projects transversely and are located on the four flanges defined by the pairs of walls; the formed portions of the funnel having a transverse extension equal to about one tenth of the width and extending longitudinally from the first end of at least one first portion; the funnel-shaped portions tapering towards the second end, which at least has a first portion has a substantially rectangular cross-section without projections.

5. The mold according to one of the preceding claims, characterized in that the minimum value of R2 of the radius of curvature is an optimum value for subsequently rolling the solidified metal emitted from the casting duct.

6. The mold according to one of claims 3 to 5, characterized in that the radius between the variation and the radii of curvature of the flanges between two predetermined sections of the at least one first portion and a distance between two predetermined sections is approximately 0.0025 a along a first portion of at least a first portion, and is approximately 0.002 along a second portion, consecutively with the first portion in the direction of flow of the molten metal in the casting conduit, at least a first portion; the second part has a longitudinal extension approximately 12% shorter than the longitudinal extension of the first part.

7. The mold according to one of the preceding claims, characterized in that the casting duct also comprises a second portion having the substantially rectangular internal section of the constant area, and defined by respective perpendicular extensions of the pairs of walls, the second portion being consecutive with at least one first portion, and has a casting metal of inlet section coincident with an outlet section of the casting metal at least a first portion; the first portion has rounded internal ridges with a radius of curvature that is along the constant length of the full longitudinal extent of the second portion and equal to the minimum value R2 of the radii of curvature.

8. The mold in accordance with the claim 7, characterized in that at least the first portion has a longitudinal extension approximately equal to the longitudinal extension of the second portion.

9. The mold in accordance with the claim 8, characterized in that at least one first portion has a longitudinal extension shorter than the longitudinal extension of the second portion.

10. The ingot mold according to one of the preceding claims, characterized in that the casting duct is curved; the walls of the first pair substantially parallel, the walls side by side are flat; the walls in the second pair substantially parallel, the walls side by side have a predetermined curvature.

11. The mold in accordance with the claim 10, characterized in that the ratio between the width of the curved walls in the second pair of walls is 1: 1.01.