ES2553784B1 - Distributor for steel casting - Google Patents

Abstract

Refractory distributor for steel casting comprising a chamber (11) provided on the upper base of a central inlet mouth (12) and on its side wall a series of radial outlet ducts (16). The chamber (11) is larger in diameter than the vertical metal supply duct (13) and is located above the radial ducts (16), with which it communicates through vertical passages (18). The chamber (11) has a central drain (14) in the background.

Description

5

10

fifteen

twenty

25

30

35

STEEL COLADA DEALER

DESCRIPTION

Field of the Invention

The present invention relates to a distributor for steel broth, for use in obtaining steel ingots produced by the ingot plate casting system, constituted so as to reduce defects due to impurity that may affect Special steels.

Background of the invention

At present, the ingot strainer consists of casting the broth from a spoon once the metallurgy is finished on a refractory vertical duct (formed by an initial piece called funnel and a succession of drinking tubes) that leads the broth to a refractory distributor ( called queen) which is placed on the casting plate on which the ingots are arranged. From this distributor come some refractory tubes (called interns) that lead the broth to be placed under each of the ingots. The last tube (end tube or stop) has a small vertical conduit with which the broth is entered through the bottom of the ingot.

In this sense, a distributor is known which comprises a chamber provided at its upper base with a central inlet mouth, to which a vertical molten metal supply tube is connected, and on its side wall a series of radial outlet ducts , to which many other conductive pipes of molten metal are connected.

The steel broth is released from the spoon by the closure by which a jet falls with a speed defined by the level of filling of the broth inside the spoon. The broth enters the vertical duct accelerating by gravity until it hits the bottom of the distributor at a speed around 10 m / s (under the most common conditions). The impact of the steel with the bottom of the distributor produces a release of energy that results in the erosion of the internal surfaces of the refractory.

5

10

fifteen

twenty

25

30

35

The speed of the broth through the horizontal channels maintains practically the same speed with which it reached the distributor which creates a great mechanical friction on the refractory conduit, with the consequent deterioration of the surface that produces the inclusion of impurities in the molten steel .

The quality of the steel is conditioned by the impurities that are included in the process of obtaining the ingots during the casting process.

These impurities have several origins among which the main ones are:

• Slags present in the broth located in the spoon before casting.

• Refractory that is dragged during the casting process through the refractory pipes that take the broth to the ingot.

• Oxidation of broth elements due to its exposure to ambient oxygen.

The fundamental moment of the casting process occurs at the beginning of it, when the closing of the spoon that stores the molten steel is opened. The broth falls through the vertical tube reaching a speed around 40 kms / h, producing a considerable impact on the distributor. Due to the traditional configuration of this distributor, at the intersection of the radial ducts with the chamber, edges or weak points are formed that give rise to erosions on them that are dragged by the broth and that are the origin of important inclusions in The resulting steel.

In the current design, after the first impact on the distributor, the flow is projected almost without losing speed through the through tubes. At this moment, due to the speed that gravity has conferred on it, the Froude number of the flow is greater than one, which means that it is a supercritical flow. This fact makes it inevitable that there will be a hydraulic jump in the area between the through tubes, stop tube and ingot of the ingot. The hydraulic jump has as its main characteristic the entrapment of air, which results in the oxidation of molten steel. In addition to the high speed of the flow through the through tubes, it pushes the air from the through tubes themselves towards the ingot, this air flow raising the covering powders that are precisely located at the bottom of the ingot to avoid oxidation of the steel when entering in the ingot. All these facts increase inclusions in steel.

5

10

fifteen

twenty

25

30

35

Description of the invention

The present invention is intended to provide a refractory distributor constituted so as to prevent the slags already present in the bucket from reaching the ingot mold, further refusing erosions and dragging of the refractory ducts and limiting the oxidation phenomenon that occurs during the conduction itself and when entering the ingot.

The distributor of the invention is of the aforementioned type, constituted by a chamber provided at its upper base with a central inlet mouth, to which a vertical molten metal supply tube is connected, while in the side wall it has a series radial outlet ducts to which many other conductive pipes of molten metal are connected.

In accordance with the invention, the distributor chamber is larger in diameter than the vertical molten metal supply duct and is located above the radial outlet ducts, with which it communicates through vertical passages that start from the bottom of the chamber and drain, one in each radial duct.

According to another characteristic of the invention, the distributor chamber has at the bottom a central drain that is closed laterally and inferiorly and forms a vessel, opened by its upper base, which is approximately equal in diameter to that of the vertical pipe of the molten metal supply .

With the constitution described, the weak points presented by the traditional distributors at the intersection between the radial outlet pipes and the distributor chamber are eliminated. In the distributor of the invention there are no edges of reduced thickness that constitute weak points easily eroded by the flow of the broth.

In the distributor of the invention the chamber is of horizontal section at least equal and preferably greater than the sum of the cross sections of the radial ducts.

With all this, in the distributor of the invention, the molten metal that falls through the vertical tube loses almost all of its speed when it reaches the vessel, without leaving the distributor. This causes the hydraulic jump to occur in the distributor itself.

5

10

fifteen

twenty

25

30

35

Thanks to the interior constitution of the distributor of the invention, with the existence of the vessel, the chamber located above the radial outlet ducts and the connection labyrinth between the radial outlet tubes and the chamber, the distributor acts even from the moment of the initial impact as a filter. The reduction of speed caused by preventing its progression and the increase of the section in the chamber, makes the inclusions to be of much lower density than the molten steel can return upwards, instead of continuing with the steel path of the ingot.

Brief description of the drawings

The attached drawings show an example of realization, not limitation, through which description the characteristics and advantages of the invention will be better understood.

In the drawings:

- Figure 1 shows in plan a traditional installation of ingot casting.

- Figure 2 shows in vertical section the same installation, according to the cutting line 11-11 of figure 1.

- Figure 3 is a horizontal section of the distributor including the installation of figures 1 and 2.

- Figure 4 shows in side elevation the distributor of the invention.

- Figure 5 is a top plan view of the distributor of Figure 4.

- Figure 6 is a horizontal section of the distributor of the invention, taken according to the cutting line VI-VI of Figure 4.

- Figure 7 is a section of the distributor of the invention, taken according to the cutting line VII-VII of Figure 5.

- Figure 8 shows in perspective the same section of Figure 7.

Detailed description of an embodiment

Figures 1 and 2 show a traditional installation of ingot casting, in which from a spoon not shown the molten metal is poured over a refractory vertical duct (1) that is formed by an initial funnel (2) and a succession of drinking tubes (3). This vertical conduit (1) conducts the molten metal to a refractory distributor (4) that forms a chamber (5) from whose wall a series of radial conduits (6) to which pipes (7) connecting the pipe are connected.

5

10

fifteen

twenty

25

30

broth until they are placed under the ingot molds, where they can be finished off in an entry elbow (8) at the bottom of the ingot box.

The broth that is poured into the funnel (2) reaches a relatively high speed along the vertical tube (1) producing an impact on the distributor (4) that causes a certain erosion on it. This effect is increased by the internal geometry of the distributor (4) because the mouth of the radial ducts (6) in the chamber (5) delimits, between consecutive ducts (6), edges (9), figure 3, which they constitute easily erodible weak points, originating materials that are dragged by the broth and that are the origin of important inclusions in the resulting steel.

Another negative effect presented by the geometry of the distributor of Figures 1 to 3 is, as indicated above, the hydraulic jump that occurs between the end of the horizontal tubes (7), the elbow (8) and bottom of the ingot mold, which is the cause of entrapment of air bubbles, which cause oxidation of molten steel. In addition, the high velocity of the flow through the horizontal tubes (7) pushes the air from the tubes themselves towards the ingot, raising the cover dusts that are located at the bottom of said ingot to avoid oxidation of the steel.

The drawbacks caused by the distributor shown in Figures 1 to 3 are eliminated with the distributor (10) of the invention represented in Figures 4 to 8.

This distributor (10) comprises a chamber (11) with a central inlet mouth (12) to which the vertical pipe (13) of molten metal supply is connected. As can be seen in Figures 7 and 8, the chamber (11) is of a diameter far superior to the vertical conduit (13) for supplying molten metal.

The distributor (10) has a central drain (14) at the bottom, which is closed laterally and inferiorly and which forms a vessel (15) opened by its upper base and whose diameter is approximately equal to that of the vertical tube (13) and central entrance mouth (12). Around the vessel (15) radial outflow ducts (16) start, to which many other conductive tubes (17) of the molten metal are connected to the ingot. The radial ducts (16) communicate with the chamber (11) through vertical passages (18) that start from the bottom of the chamber (11) and end inferiorly in the radial ducts (16).

With the constitution described the chamber (11) is located above the radial ducts (16), with which it communicates through the vertical passages (18).

5

10

fifteen

twenty

25

The chamber (11) will be of section at least equal and preferably greater than the sum of the cross sections of the radial duct assembly (16).

With the constitution described and as can be seen in Figures 6 to 8, between the radial ducts, vertical passages (18) and chamber (11) no sharp edges are formed that may constitute points of easy erosion.

On the other hand, the molten metal that reaches the distributor through the vertical tube (13) falls into the vessel (14), from which it overflows and passes to the radial ducts (16) through the vertical passages (18), reducing considerably the speed of molten metal. This speed reduction, together with the larger section of the chamber (11), makes the inclusions, of much lower density than the molten steel, can return upwards, instead of continuing with the current of steel ingot path.

When the molten metal falls into the vessel (11), the metal stream is forced to rise until it reaches the chamber (11), thereby reducing its kinetic energy.

On the other hand, with the described constitution it is achieved that the hydraulic jump occurs in the center of the distributor (10), due to the existence of the vessel (15) that receives the molten metal and overflows until reaching the chamber (11).

By means of the distributor of the invention it is achieved that the speed of advance of the molten metal, towards the ingot mold, depends on the flow rate and not on the rate of fall, achieving a reduction of feed rate up to approximately three meters per second. This reduction in speed means a reduction in the friction between the molten metal stream and the surface of the refractory ducts, which significantly reduces the risk of refractory detachment due to the mechanical action of the flow.

Another effect of reducing the velocity of molten metal in the distributor is that the speed with which the air contained in the tubes (17) to the ingot is released is substantially reduced.

Claims (2)

ES 2 553 784 A1 1.- Refractory distributor for steel casting, comprising a chamber (11) provided at its upper base with a central inlet mouth (12), to which a vertical pipe (13) of molten metal supply is connected, and on its side wall a series of radial outlet ducts (16) to which many other conductive pipes (17) of the molten metal are connected, characterized in that the aforementioned chamber: - It is larger in diameter than the vertical conduit (13) for supplying molten metal; 10 - It is located above the radial ducts (16) of exit; - It communicates with the radial ducts (16) through vertical passages (18) that start from the bottom of the chamber (11) and open, one in each radial duct (16); - It has a central drain (14) at the bottom, closed laterally and inferiorly, 15 that forms a vessel (15) opened by its upper base and diameter approximately equal to that of the vertical pipe (13) for supplying molten metal. 2. Distributor according to claim 1, characterized in that the chamber (11) is of horizontal section at least equal and preferably greater than the sum of the cross section 20 of the radial duct assembly (16).