DE8907044U1 - Retention or pouring device for containers for molten metal - Google Patents

Abstract

The invention relates to means for retaining contaminations in metal melting baths, e.g. a tundish containing molten metal. Contaminations, e.g. from slag and other covering layers on the metal surface, can pass through the outlet of the tundish and hence contaminate the cast metal. The invention aims to avoid this problem by providing an annular buoyancy body (2) which surrounds the outlet (4), the body (2) being in the form of a protective ring preventing particles (10, 11) floating on the surface of the metal (12) from entering outlet (4). The body (2) may be constrained to surround a starting tube (1) which surrounds outlet (4) and to float up the starting tube (1) with increasing depth of molten metal (12). Pouring openings (3) in the starting tube (1) are thereby effectively closed by body (2) as the slag-covered surface of the metal (12) rises above the openings (3) and the openings (3) are then exposed to allow molten metal (12) to flow through only after layers (10, 11) of potential contaminations have safely passed.

Description

.* ag. _

Foa«co International Liaitad Biraingha» B 7 5 JR

(•SroAbri ta&niaoI

Rttukhalt*- bsw.

The invention relates to a device for holding impurities in a melted steel in a container, a ladle, a distributor device, a trough or the like. The invention relates in particular to a pouring device for distributor channels for receiving molten metal (steel) and for passing it on to a mold, a continuous casting plant. When pouring steel using the continuous casting process into a water-cooled mold, the steel is led from a ladle into a distributor channel, which has outlets in the bottom according to the positioning of the molds. To regulate the flow of steel into the molds, the distributor channel is equipped either with slide valves from below or with plugs from above, or in the case of free-running molds only with pouring nozzles. Depending on the pouring systems used, the pouring areas are heated from below or from above with burners before use to prevent freezing during pouring. The first part of the steel that reaches the distribution channel and is distributed there to the pouring outlets is characterized by low temperatures and contamination, which on the one hand come from refractory particles from the distributor lining, from the slide sand and from the oxidation of the steel during pouring.

If heating is not sufficient, the following disadvantages occur, especially with slide valves and freewheels:

1. Freezing of the steel in the sink.

2. Introduction of impurities into the first part of the strand, which leads to a devaluation or scrapping of this first strand part.

3. The impurities present in the casting steel can also partially lead to the blockage of the immersion pipes installed under the tundish.

In order to avoid this problem, dams were installed in the past, for example, which caused the impurities to rise by blocking the pouring steel and also increased the pouring temperatures by mixing the subsequent hot steel with the initially cold steel due to the high steel volume. However, this did not prevent the impurities floating on the surface from entering the pouring spouts during the pouring phase and thus, as already described, leading to a reduction in the pouring range or pouring difficulties. Even filters used on a trial basis in the pouring spout were unable to solve these problems due to blockages or freezing difficulties.

In the further course of development, starter pipes were used for slide valves, independently of the damming and filtering above the spouts. These starter pipes, as cylindrical pipes with an inner diameter corresponding to the pouring funnel, caused a temporary sealing of the spout and thus increased the pouring temperature, but could not prevent the impurities floating on the surface from reaching the

t II «ftf
11*1 · *

If Il

I I f

I I I &igr;&igr;

Final height of the starter pipe or the overflow openings in the starter pipes first reached the drain M .

The invention is based on the object of designing devices of the types mentioned at the outset in such a way that it is ensured that in the emerging cast strand, only one ^{unit is} formed.

This is achieved by the features specified in the claims.

At the heart of the invention is the ring-shaped buoyancy body, which is guided either on the starter tube or the plug or, in the case of free-running machines, on a suitable device in such a way that it prevents slag from entering the discharge. The protective ring serves as a blocking part and protrudes with its upper extension far enough above the surface of the bath level that no slag particles or the like can pass over its upper edge into the interior of the

Protective measures in the German-speaking world are in place.

By taking into account the protective ring and the specific weight ic in relation to the particles floating on the surface of the melt or of the melt itself, such a projection above the bath level can be achieved, regardless of ^the height at which the bath level is located.

The upward mobility of the protective ring can be achieved by a .,

This can prevent the protective ring from coming off the

Starter pipe releases. i

The protective ring can also be fixed at a specific position in relation to the starter pipe or its overflow openings. This can prevent the dreaded vortex

• «ti · I III I·· ·

t ti ti« ft 4. (Q · _ ''"

I It · t · I T 5>« t I

I I I ·· I · t f

This effect can be counteracted by changing the pan and causing the level in the distribution channel to drop.

According to a preferred embodiment of the invention, the starter tube can also be provided with openings in the lower area. However, these openings are initially closed by sheet metal parts, so that they cannot initially perform any function when pouring. However, under the influence of the high temperature of the melt, these sheets are melted, so that steel can now pass through these openings into the pouring spout. In the normal melting process, this is not necessary in and of itself, since the overflow openings in the upper part of the starter tube fulfill this function. At the end of the sequence, however, these lower openings take on the function of allowing the steel to flow out of the distribution channel, so that a small residue (so-called bear) is created.

The invention is explained below by way of example with reference to the drawing.

Fig. 1 showed a pouring device according to the invention with a slide valve.

Fig. 2 shows a pouring device according to the invention with a plug closure.

In the figures, the protective ring according to the invention is designated by 2, while the pouring funnel or the pouring opening is designated by 4. The melt itself is designated by 12, on which are contaminant particles, which can essentially be referred to as slag and are designated by 11. Above the slag is insulating material 10.

• · f t · t ·

t ·· II* tt*»t

• ti ■ t it t
ti ti

The distribution trough is provided with a lining 13, which is replaced when it wears out. Underneath this is a permanent lining 14 and a cover lining 15. The housing of the distribution trough itself is designated 16.

In Fig. 2, a plug 6 is shown which, as far as the function of the protective ring 2 is concerned, performs more or less the same function as the starter tube 1 shown in Fig. 1.

The conditions that exist in a freewheel can also be described using Figure 1. The guide provided for the protective ring 2 according to the invention can have the shape of a cylinder that has the shape of the starter tube 1 shown in Figure 1 and is open at the top.

As far as the present invention is concerned, the Conditions at the individual ÄüSyüovüEiichtUfiyen, »«Smiich

with a slide closure 17 or with a plug 6 or as a freewheel, so that the invention is explained and described below in connection with Figure 1.

The starter tube shown in Fig. 1 is placed on the spout 4. It can be covered in its upper area, at 23, for example by a one-piece design or by a cover. The starter tube is designed in the upper area with overflow openings 3, which have a certain height and are distributed over the circumference of the starter tube 1. The overflow openings 3 have a total area that is matched to the inlet opening of the funnel 4.

I · t tt * t

21 designates a projection in the upper area of the starter tube 1 which prevents the floating protective ring from detaching upwards from the starter tube 1. 20 designates a projection which is suitably dimensioned so that once the protective ring 2 has engaged with it, it prevents the protective ring 2 from detaching from the starter tube 1.

In the lower area, another opening of the starter tube 1 is shown at 22, although a plurality of such openings can be formed distributed over the circumference of the starter tube 1. This opening 22 is closed by the part shown in black, so that these openings cannot initially perform any function. However, if the black sheet metal part melts under the influence of L the temperature of the melt 12, steel can be heated by the

·& opening 22. Since the openings 22 are relatively

are located far down in the starter pipe, it can be achieved that the distribution channel is largely emptied at the end of the sequence ==. Here too, there is no danger of slag

Sj 11 or insulating material 10 enters the cast strand, since the

^r Protective ring 2 when the bath level drops, these openings

22 in the same way as the openings 3. The r use of such starter tubes is compared to the

j3? common practice is advantageous, since previously used

Procedure after the actual starting process, the starter tube 1 is removed. This creates the risk that

ff Leakage of the distributor rings Contaminants in the

§ Casting strand.

The inner body 1 shown in Figure 1 with an inner diameter corresponding to the diameter of the 'inlet funnel (Tundak) is placed on the pouring funnel and

et·· ■·« $ &bgr;&lgr;&bgr;

• · « &igr; a deep

« t · ■ &bgr; $

&igr; ·*■<· « &igr;

(C

M t· »f Mtl ·* t ·

·· · it I · · ((III

> I ··! 1 i t » Mill····

I · ( I I I t I " I

The inner body 1 is fixed to the tundish floor wearing material and secured and sealed in such a way that when pouring on no steel can get directly into the spout 4 and the inner body 1 cannot float up. This inner body 1 is closed at the top and has slots 3 in the bottom at a specified distance from the wearing material, which are dimensioned so that the amount of steel passing through is greater than the specified diameter of the spout. A ring 2 is placed around the inner body 1, which is geometrically designed so that it floats up due to the buoyancy caused by the steel and assumes a floating position between the steel and the slag. As the steel rises when pouring on in the tundish ^, the ring 2 is moved upwards along the inner body 1 and thus prevents the slag from overflowing from the surface of the steel into the spout 4 when the slots 3 are in the position. As the height of steel in the tundish continues to rise and the ring 2 moves further upwards, the slots 3 are cleared for the passage of steel and are then fed with clean and hot steel. As the tundish is filled to the final steel height, the ring 2 floats completely and is then of no further use. The closed inner body 1 prevents the so-called vortex effect, ie the drawing of slag into the pouring spout, as long as it remains in position, even during ladle changes which are characterized by a drop in the steel level. In order to avoid an excessive amount of steel in the tundish at the end of the pouring sequence which is characterized by the inlet height of the slots 3, the inner body 1 is designed in such a way that it leaves its position at the end of the sequence and floats or is mechanically forced to do so. In order to maintain the functionality of the entire system over an entire sequence, the inner body 1 is designed in such a way that the floating ring 2 is prevented from floating further during the casting g at the upper part of the inner body 1. This has the consequence that when the J-

C i 4 «I · · ·· · t

Steel levels during the ladle change within a sequence or at the end of a sequence at slot height the floating ring in turn prevents slag and powder from flowing into the inner body 1. The inner body is designed in such a way that preheating of the pouring system, which is now usually carried out from below, is possible. Care must be taken that the gases generated by the burners can escape through the slag pan 3 without causing any particular blockages. The heating of the pouring system is therefore more intensive, so that the heating time or the energy density of the burners can be reduced. There is also nothing to prevent the usual tundish from being heated from above, since both systems - heating from below and heating from above - can work independently of one another. Due to the high hardening reservoir after heating, it is possible to extend the interruption between heating and use of the tundish while maintaining the same level of preheating.

With cold-started free-runners, suitable short-term closure of the nozzles and different heights of the slots 3 in the inner bodies 1 of the individual strands, a delayed, automatic start-up of the individual strands can be achieved. The system is also suitable for the intended covering material to be placed on the distributor base for insulation immediately after heating before steel is introduced into the distributor channel, since the floating ring 2 around the inner body 1 prevents the corresponding slag or the still loose covering material from flowing into the pouring system. This avoids the previously occurring supply of oxygen to the steel surface and at the same time reduces the radiation of heat or the reduction of the steel casting temperature in the tundish in the first few minutes of start-up.

&bull; · ft a r. , &ldquor;&ogr; .: ^ J

In the case of plug-regulated tundishes (Fig. 2), only the floating ring 2 is placed around the plug, which floats with the inflowing steel and prevents increased erosion of the plug in the slag or the contaminated steel zone during casting. The partial formation of sludge of the basic covering , together with the slag, influences the plug function and can thus be avoided. A slag or covering agent applied between plug 6 and ring 2 also prevents the oxidation which may occur in the gap 7 between ring 2 and plug 6. These agents can be a component of ring 2. The advantage of introducing slag forming agents or covering agents is also present without damaging the plug. The covering agents or slag forming agents can, however, also be added separately between ring 2 and plug 6. In addition, when used together with plug 6, ring 2 ensures a suitable heat balance of the plug tip during start-up.

Claims (13)

Protective claims 1. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a pouring device for a distributor channel for receiving molten metal (steel) and for passing it on to molds of a continuous casting plant, the pouring device having a starter pipe which can be placed on the pouring spout or its pouring funnel and which has overflow openings for the melt distributed over its circumference in the upper area so that the melt only reaches the molds when it reaches the overflow opening, characterized by a buoyancy body (2) surrounding the starter pipe (1) at a distance in the form of a protective ring which prevents particles (10, 11) floating on the surface of the melt (IL) from entering the overflow openings (3). Ir.'lpf.n 402172 Ir'lephrmrj IeIf;« 10 40) IH 12 3.J ■'.7 WJ' (0 40) 12 34 &bull;'■ill Jn " · ' ' " JHJfI|pUl|) Y] t Hamburg KIo Hf 8Ü2 02 202 FiI / 2OO1QO2O I! 1/1" /f ff'lf)M.;in(r Kl'i Nf 46 51'J(JBO HI / /&Ogr;&Ogr;;&Oacgr;2 /'J 2. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a pouring device for a distributor channel for receiving molten metal (steel) and for passing it on into molds of a continuous casting plant, the pouring device having a plug closing the pouring spout or its pouring funnel, which is raised when a certain bath level is reached, characterized by a buoyancy body (2) surrounding the plug (6) at a distance in the form of a protective ring which prevents particles (10, 11) floating on the surface of the melt (12) from entering the pouring spout (4). 3. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a pouring device for a distributor channel for receiving molten metal (steel) and for passing it on into molds of a free-running continuous casting plant, wherein the pouring device has a pouring spout or a pouring funnel, characterized by a movable buoyancy body (2) guided above the pouring spout (4) and ■ surrounding the pouring spout (4) in the form of a protective ring that prevents particles (10, 11) floating on the surface of the melt (12) from entering the pouring spout (4). I 4.Device for retaining impurities in a metal melt in a container, a ladle, a distributor, a tundish or the like, in particular a device according _to one of the preceding claims 1 to 3, characterized in that characterized in that the protective ring (2) is made of a material whose specific weight is greater than that of the particles floating on the surface (oxides, slag, refractory parts, distributor abrasion, slide sand and the like) and smaller than that of the melt. 5. Device for retaining impurities in a metal melt in a container, a ladle, a distributor, a tundish or the like, in particular a device according to one of the preceding claims 1 to 4, characterized in that the specific weight of the material of the protective ring (2) is closer to that of the particles floating on the surface than to that of the melt. 6. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of the preceding claims 1 to 5, characterized in that the protective ring (2) is designed with a cross-section tapering downwards, preferably conically extending on the outside. 7. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of the preceding claims 1, 2, 4 to 6, characterized in that the annular gap (7) formed between the protective ring (2) and the starter tube (1) or plug (6) has a cross-sectional area substantially corresponding to the spout (4). 8. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of claims 1, 4 to 7, characterized by a stop (21) on the starter tube (1) which limits the upward mobility of the protective ring (2) on the starter tube (1). 9. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of claims 1, 4 to 8, characterized by a projection (20) on the starter tube (1) which fixes the protective ring (2) in a specific position with respect to the overflow openings (3). 10. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of claims 1, 4 to 9, characterized in that the starter tube (1) is designed to be closed at the top (23) or can be covered by means of a lid. 11. Device for retaining impurities in a metal melt in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of claims 1, 4 to 10, characterized in that the starter tube (1) is provided in the lower region with openings (22) which are closed by means of meltable sheet metal parts. &bull;to · · * · f I &bull;t t · 12. Device for retaining impurities in a molten metal in a container, a ladle, a distributor, a tundish or the like, in particular a device according to one of claims 1 to 11, characterized in that the protective ring is made of ceramic material. 13. Device for retaining impurities in a molten metal in a container, a ladle, a distributor device, a tundish or the like, in particular a device according to one of claims 1 to 12, characterized in that the protective ring (2) consists, among other things, of slag-forming and covering materials.