GB2226263A

GB2226263A - Rotary outlet valve in metallurgical vessel

Info

Publication number: GB2226263A
Application number: GB8829977A
Authority: GB
Inventors: Roger Wallis
Original assignee: Steel Castings Research and Trade Association
Current assignee: Steel Castings Research and Trade Association
Priority date: 1988-12-22
Filing date: 1988-12-22
Publication date: 1990-06-27
Anticipated expiration: 2008-12-22
Also published as: GB2226263B; GB8829977D0

Abstract

The floor (3) of a foundry ladle (1) has a hole (5) containing a rotatable nozzle (12). The hole also contains a seating (8). The nozzle has a passageway (23) having an entry port (24) which in one extreme rotational condition is blocked off by a high side of a seating (8). The seating (8) has a low side wall on the other side. A lever (15) below the ladle (1) can be used to rotate the nozzle (12) between the blocked and open conditions, and the rate of flow can be controlled by the extent of rotation to expose all or part of the entry port (24) to the molten metal. <IMAGE>

Description

VALVE FOR VESSEL OUTLET The invention relates to a metallurgical vessel, typically a ladle, intended for use in a foundry, and in particular to one having a bottom outlet through which molten metal can be dispensed in a predetermined way.

It is known to mount a refractory nozzle in the bottom outlet in the floor of the vessel, and to provide a socalled stopper rod above the vessel, the rod being lowered or raised respectively to close or open the outlet. The rod comprises a metal shaft surrounded by a refractory sleeve.

This valve system has disadvantages; for example, the rod becomes distorted in use; if it is used as a throttle the metal stream breaks up which affects casting quality; blockages can happen; and there is a relatively long turn around period when changing a used refractory sleeve of the stopper rod.

An alternative device is a so called sliding gate valve which is mounted externally below the bottom outlet. This is used on bulk steel ladles where liquid metal is discharged in a few pours. In the foundry however, the outlet is opened and closed frequently and there can be long intervals between one opening and the next, and liquid metal can freeze upon a sliding gate valve which is why it is not suitable for use with foundry ladles. Liquid steel is especially prone to this 'freezing-off' and therefore there is a serious risk of such valve blockage.

It is one object of the invention to satisfy the need for a valve for use with a foundry ladle or like vessel having a bottom outlet able to meet the requirements of use.

In one aspect the invention provides a foundry ladle or like vessel comprising an outer metal shell and a refractory lining, the vessel having a floor including an outlet, the outlet containing a seating for a nozzle, the nozzle having a through passageway for the passage of liquid metal therethrough characterised in that the nozzle is arranged for rotation between one position where a part of the seating obscures the entry end of the through passageway and another position where the entry end of the through passageway is exposed to the interior of the vessel and in that means are provided for rotating the nozzle.

While the nozzle and the seating may be of any suitable shape, it is preferred that the entry end of the through passageway is disposed in a side of the nozzle and the seating has a wall portion which obscures or exposes that entry end.

In a preferred aspect therefore, the invention provides a vessel as defined characterised in that the entry end of the through passageway is at a side face of the nozzle and in that the seating includes a wall of non-uniform height so that when the nozzle is in one position the higher part of the wall obscures the entry end of the through passageway and when the nozzle is in another position the lower part of the wall allows the entry end to be exposed to the interior of the vessel.

Most preferably, the rotating means comprises a handle or the like attached to the depending portion of the nozzle outside the ladle. It is a much preferred feature of the invention that the rotating means be arranged to move the nozzle progressively from the totally open to the totally closed positions so that metal flow can be throttled.

Most preferably the seating is located in a base block, and the blocks have a small mating area to reduce the force required for the rotating means to move the nozzle and also to reduce the risk of metal freeze between the parts.

It is a much preferred feature of the invention that the seating be accessible from the outside of the ladle so that it can be changed from the outside when required.

In order that the invention may be well understood it will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which Figure 1 is a vertical sectional view of the lower portion of a foundry ladle of the invention with the valve in the closed condition; and Figures 2A to 2C are transverse sectional views showing the nozzle of the valve in different positions.

The ladle comprises an outer metal shell 1 defining a side wall 2 and a floor 3. A refractory lining 4 is present on the inside of the ladle which may have a capacity of from less than 1 tonne to at least 10 tonnes. The floor 3 has a hole 5 extending to the outside. A refractory base block 6 is received in the hole 5. The block 6 has a frustoconical hole 7 in which is received a refractory hollow seating block 8 of complementary shape. The hole 9 of the block 8 has an upper narrower part 10 which receives the head 11 of a nozzle 12. As shown1 one side 6A, SA of the blocks 6 and 8 respectively is higher than the other, (the left hand side as seen in Figure 1) and the head 11 is dimensioned so that the top thereof is level with the top of the blocks 6 and 8.

A plate 13 is bolted to the underside of the floor 3 about the hole 5 and holds the blocks 6 and 8 in place.

The nozzle 12 has a depending shank 14. A lever arm 15 is located to one side of the shank 12 and is long enough to extend beyond the outside of the ladle. A clamp ring 16 is mounted below the handle 15 and at one side is secured to the underside of the ladle by a support 17. A spigot 18 is received in a hole 19 in the underside of the nozzle head 11. There are three such spigot pins 18 and holes 19 are equispaced around the underside of the nozzle head 11, thus causing the nozzle to turn as the handle 15 is rotated. The spigot pin 18 has a collar 20 and disc compression springs 21, act on the collar 20 with thrust bearing pads 22 in between. In this way the nozzle is urged into fluid tight engagement with the seat.

The nozzle has a passageway 23 by which molten metal in the interior of the ladle may be dispensed to below. The passageway 23 extends between an entry port 24 in one side face of the head 11, shortly below the top thereof, and then changes direction through an acute angle 25 to form a vertically downward pipe 26. As shown, the pipe 26 has rifling 27 far improved laminar flow. In the condition shown in Figure 1 the entry port 24 is obscured by the higher wall of the seat 8 whereas if the nozzle is turned through 1800 the entry port 24 will stand proud cf the lower wall of the seat block 8 and molten metal will be able to enter the passageway 23 via the exposed entry port 24.

A shroud 30 is mounted on the lower end of the nozzle shank 14 and extends below it so that argon gas entering the shroud 30 via the inlet 31 may pass through a porous ceramic block 32 to shroud the emergent molten metal stream.

In use, the lever 15 is moved to rotate the nozzle so that the head 11 is in the closed condition shown in Figure 1.

When molten metal is to be dispensed the lever 15 is moved so rotating the nozzle head 11 to a corresponding extent.

This allows molten metal into the entry port 2A and out via the pipe 26 to be dispensed e.g. to a mould. When sufficient metal has been dispensed the lever 15 is moved back so closing the valve. The rate of flow can be controlled by the extent of rotation of the nozzle head 11 so exposing all or just part of the entry port 24 to molten metal in the ladle.

In Figure 2A the nozzle is rotated so that the valve is closed; Figure 2B shows an intermediate position and Figure 2C shows the nozzle rotated to the maximum flow condition.

The invention is advantageous because the valve can be controlled accurately. Because there is a small mating area between the blocks 6 and 8 the force required to move the lever 15 is reduced and the pressure is more likely to be applied evenly. If the blocks 6 and 8 are made of refractory materials of different degrees of hardness, one will be ground in relative to the other to ensure good mating surfaces. When repair or replacement is needed, access to the parts is gained from outside the ladle.

Claims

1. A metallurgical vessel (I) comprising an outer metal shell (2) and a refractory lining (4), the vessel having a floor (3) including an outlet (5), the outlet containing a seating (8) for a nozzle (12), the nozzle having a through passageway for the passage of liquid metal therethrough characterised in that the nozzle (12) is arranged for rotation between one position where a part of the seating (8) obscures the entry end (24) of the through passageway (23) and another position where the entry end (24) of the through passageway (23) is exposed to the interior of the vessel (1) and in that means (15) are provided for rotating the nozzle.

2. A vessel according to Claim 1 characterised in that the entry end (24) of the through passageway (23) is disposed in a side of the nozzle (12) and the seating (8) has a wall portion (8a) which obscures or exposes that entry end (24).

3. A vessel according to Claim 2 characterised in that the entry end (24) of the through passageway (23) is at a side face of the nozzle (12) and in that the seating includes a wall (8a) of non-uniform height so that when the nozzle (12) is in one position the higher part of the wall (8a) obscures the entry end (24) of the through passageway (23) and when the nozzle (12) is in another position the lower part of the wall (8) allows the entry end (24) to be exposed to the interior of the vessel (1).

4. A vessel according to any preceding Claim characterised in that the rotating means (15) comprises a handle attached to the depending portion of the nozzle (12) outside the ladle (1).

5. A vessel according to any preceding Claim characterised in that the rotating means (15) is arranged to move the nozzle progressively from the totally open to the totally closed positions so that metal flow can be throttled.

6. A vessel according to any preceding Claim characterised in that the seating (8) is located in a base block (6) and the blocks (8,6) have a small mating area.

7. A vessel according to any preceding Claim characterised in that the seating (8) is accessible from the outside of the ladle.

8. A metallurgical vessel substantially as described with reference to the drawings.