GB2267051A

GB2267051A - Heating device for continuous casting plant

Info

Publication number: GB2267051A
Application number: GB9308727A
Authority: GB
Inventors: Hans Josef Bebber; Peter Stadler
Original assignee: INDUGA IND und GIEBEREI ANLAGE
Current assignee: INDUGA IND und GIEBEREI ANLAGE
Priority date: 1992-04-27
Filing date: 1993-04-27
Publication date: 1993-11-24
Anticipated expiration: 2013-04-27
Also published as: DE4214539C1; GB2267051B; FR2690365A1; JPH0663709A; GB9308727D0

Description

2267051 A HEATING DEVICE FOR A CONTINUOUS METAL CASTING PLANT The

invention relates to a heating device for a continuous metal casting plant.

Continuous casting plants usually have a tundish which is filled with material flowing from a ladle and from which the molten material is supplied to a mould, e.g. via lip arranged in the vicinity of the base in the case of horizontal continuous casting plant, and arranged in the base in the case of a vertical continuous casting plant.

A continuous casting installation for steel is described in 11Berg- und Hiltten-m&nnischen Monatsheftenll, Vol. 128, No. 3, March 1983. An installation including a tundish with a lip, a nozzle brick arranged at the lip, a tear-off ring and a horizontal continuous casting mould is shown in diagrammatic form. Various possibilities for cooling the mould are described. Heating of the tundish is not provided for.

A counter electrode is required when using a direct-current heating device for the tundish. A heating device of this kind is known from STEEL TIMES1 July 1988, p. 381, and also from U.S. Patent 4686687. The anode is arranged in the region of the lip.

German Patent 3339514 shows in detail an arrangement of an electrode of this kind in heat vessels, in particular in furnaces or channels, in which a pencil-shaped electrode is arranged in the refractory material. The electrode has channels for conducting a cooling medium. The electrical contact with the molten material is produced via metal adhering to the head of the electrode which is made of copper.

Counter electrodes of this and similar designs produce a weak point in the bottom of the vessel. The construction is expensive and difficult to adapt it thermally to the refractory material. Moreover, it produces an obstruction to current conduction from the metal electrode to the molten material.

A process and a device are known from German Patent Application 3443740, in which energy is supplied to molten 2 metal in a tundish via plasma torch burners. However, in this case two alternating-current burners are used, the current path being guided through the plasma torch burners, so that no bottom electrode is required.

It is an object of this invention to provide a heating device for a continuous metal casting plant, in which a reliable low-loss energy supply is ensured by simple means with temperature control of the melting charge being finely adjustable.

In accordance with the invention, a heating device for a continuous metal casting plant having a tundish and a continuous casting mould arranged at the lip of the tundish comprises a direct current burner which projects into the tundish and a counter electrode in the form of an at least partially tubular member of conductive material which surrounds and contacts metal emerging from the tundish.

The counter electrode of the direct-current burner heated tundish is designed as a tubular member arranged at the lip of the tundish which embraces the metal emerging from the tundish in a contacting manner. As a result of this, the counter electrode does not constitute a weak point of the tundish, in particular at the bottom of the vessel.

The tubular design ensures a large area of contact with the melting charge and thus reliable current conduction.

The melting charge is either still fluid or just pasty at the prescribed point at the lip of the tundish in the region of the current contact, so that the melting charge intimately contacts the inner wall of the tubular member counter electrode.

The counter electrode has channels through which a cooling medium can be passed. The coolant channels are suitably provided on the outer face of the tubular member. Wear of the counter electrode can be reduced and moreover heat dissipation from the melting charge can be adjusted by 3 adjustment of the temperature of the cooling medium which can be accurately effected.

The counter electrode can be made of copper and the outer wall of the copper electrode can be allowed to come into direct contact with the molten charge. This is particularly achieved by using a cooling -medium, the temperature of which is readily controlled, generally water. Moreover, the flow of the metal, in particular when casting steel, ensures that the quality of the contact is not reduced by caking.

When using the counter electrode at the tundish, lip, i.e. in front of the mould in the direction of metal flow, heat dissipation is such that the counter electrode is subject to only minimum wear, while the smallest possible quantity of heat is dissipated and the casting material remains substantially fluid.

The counter electrode may alternatively or additionally form part of the continuous casting mould. When using the counter electrode in the region of the mould in a horizontal continuous casting plant with a two-piece mould, the tubular member, is simply further provided with supply terminals, the de sign thus remaining almost unchanged. The molten charge is either still fluid or just pasty in the region behind the tear-off ring,in the direction of flow, so that the thin strand shell sits closely against the inner face of the copper tubular member.

The internal bore of the mould may have a conical design in accordance with the cooling and reduction in diameter of the strand. The current supply to the strand is ensured as the contact between the molten charge and the inner shell of the mould, which in the case of a two-piece mould can consist of copper and graphite, is maintained over the entire length.

Plasma torch burners are preferably used as the burners.

Improved direct heating is achieved by arrangement 4 of the counter electrode in the region of the lip of the tundish. In a horizontal and also in a vertical continuous casting plant, the current paths extending in the mould have a positive influence on thorough mixing, temperature control and heat transfer.

The invention will now be described with reference to the accompanying drawings in which:- Figure 1 illustrates a continuous casting plant with a heating device; Figure 2 illustrates a horizontal continuous casting mould; and Figure 3 illustrates a vertical continuous casting mould.

Figure 1 shows a continuous casting plant with a tundish 10 having a lip 12. A ladle 50 can be positioned above the tundish 10, from which melt 61 is supplied to the tundish 10 through a pouring nozzle 51 which can be blocked by a gate valve 52. The tundish 10 has a metal vessel wall 11 which is covered by a refractory lining 13. A heating device 30 includes a burner 31 projecting into the tundish 10 and a counter electrode 32 arranged at the mouth of lip 12.

The plant of Figure 1 has a horizontal continuous casting mould 20 from which a strand 62 emerges.

Figure 2 shows the region of the lip 12 and the mould 20 of a horizontal continuous casting plant. The lip 12 of the tundish 10 provided with a refractory lining 13 is arranged horizontally.

In the lower part of the Figure, a tubular segment 14 made from a material displaying good conductivity, e.g. copper, is shown provided at the mouth of the lip 12. The tubular segment 14 is surrounded by a cooling element 15 which has openings for the supply 16 or removal 17 of cooling media.

A nozzle brick 21 is arranged in front of the lip 12 in the direction of flow, followed in turn by a tear-off ring 22 which is in communication with the horizontal continuous casting mould 20. A one- piece mould having a mould inner shell 25 and a mould outer jacket 23 is shown in the lower part of the Figure. Openings for the supply 26 and removal 27 of coolant media are provided on the mould outer jacket 23.

A two-piece mould is shown in the upper part of the Figure, the mould inner shell 25 of which is designed as a tubular segment 24 in the section facing the tundish 10. The material of the remaining section of the mould inner shell 25 can be graphite. Openings for the supply 26 and removal 27 of coolant are again provided on the mould outer jacket 23.

The melt 61 is shown and the solidification front of the strand 62 is indicated.

Figure 3 shows the region of the lip 12 and the mould 40 of a vertical continuous casting plant. The region of the lip 12 in Figure 3 corresponds, apart from being in the vertical position, to that already shown in Figure 2. In addition, the lip 12 can be closed by a gate valve 18. Furthermore,' there is no direct contact between the individual components of the tundish 10 and the vertical continuous casting mould 40. % The left-hand region of Figure 3 shows the counter electrode 32 arranged on the lip 12 of the tundish 10 and a normal vertical continuous casting mould with a mould outer jacket 43 and a mould inner shell 45 and openings for the supply 46 and removal 47 of coolant media.

A conventional lip 12 is illustrated on the right-hand side of Figure 3. The mould inner shell 45 of the continuous casting mould has a tubular segment 44 designed as a counter electrode 32 in the section facing the tundish 10.

The current connection between the cathodic burner and the anodic tubular segment 44 is effected via the melt 61 with the valve 18 open. After any interruption to 6 the mould filling process, the heating device must be started up again.

7

Claims

1. Heating device for a continuous metal casting plant having a tundish and a continuous casting mould arranged at the lip of the tundish comprising a direct current burner which projects into the tundish and a counter electrode in the form of an at least partially tubular member of conductive material which surrounds and contacts the metal emerging from the tundish.

2. Device as claimed in claim 1, wherein the material of the tubular member comprises copper.

3.. Device as -claimed in either Claim 1 or Claim 2, wherein at least one coolant channel is provided on the outer face of the tubular member.

4. Device as claimed in any preceding Claim, wherein the tubular member forms the mouth of the lip of the tundish.

5. Device as claimed in any preceding Claim, wherein the tubular member forms part of the continuous casting mould. L

6. Device as claimed in Claim 5, wherein the tubular member is the counter electrode of the heating device of a horizontal continuous casting plant having a radially divided horizontal continuous casting mould, the material of the inner wall of the mould portion nearest the tundish being copper and that of the mould portion remote from the tundish being graphite.