GB2227437A

GB2227437A - Heated casting tube

Info

Publication number: GB2227437A
Application number: GB9001297A
Authority: GB
Inventors: Manfred Aey; Reinhard Flender; Klaus Wuennenberg
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1989-01-31
Filing date: 1990-01-19
Publication date: 1990-08-01
Also published as: SE8904197D0; JPH02235566A; SE8904197L; GB9001297D0; DE3903210C1

Description

1 C5 1 SPOUT NOZZLE FOR CASTING METAL The invention relates to a spout

nozzle for casting metal, in particular steel. Such nozzles comprise a substantially cylindrical nozzle tube for mounting on a tundish or ladle.

A wide variety of spout nozzles or immersion tubes are used when casting metals. It is known that the casting output is determined on the one hand by the static pressure of the melt to which the teeming crosssection is subject and on the other by the cross-section of the teeming orifice. The cross- section of the teeming orifice can be determined in advance on the basis of the desired casting output, and no problems of any kind are encountered in keeping the teeming cross-section clear when casting outputs are relatively high, even when casting is carried out over a fairly long period. The procedure becomes more difficult when fairly small quantities are to be 'cast. in this case the spout nozzle has to have a relatively small cross-section, and may freeze in these cases if the temperature of the ceramic material from which the nozzles are generally made is lower than the liquidus temperature of the metal.

Generally speaking, ceramic parts which are used in casting practices are heated in a wide variety of ways, gas burners frequently being used for this purpose. However these have to be removed before the actual casting process. it is then impossible to prevent accelerated cooling of the parts. Moreover, problems may also be caused by the fact that access to these ceramic parts is sometimes restricted. This means that it is not possible to use gas burners or similar devices for heating purposes during casting, as sensitive structural parts of the rest of the apparatus can then be affected by the heating action.

German Published Specification No. 15 83 646 and German Patent Specification No. 15 25 154 propose induction coils which operate at fairly high frequencies.

2 Coils of this kind heat the metal in the spout, but not primarily the refractory material of the actual spout nozzle. It is impossible to use an induction coil of this kind for heating purposes if there is no melt in the nozzle.

The present invention is directed at a spout nozzle broadly of the type referred to above, which can enable small quantities to be cast by reducing the teeming cross-section, but without the spout nozzle freezing up, and taking into consideration the important fact that the spout nozzle is a component which is subject to wear. According to the invention, a spout nozzle comprises a cylindrical-nozzle tube; a ceramic sleeve received in the nozzle tube, the outside diameter of the ceramic sleeve being less than the inside diameter of the nozzle tube; and a cylindrical heating element, connectable to an external power source, arranged in the space between the tube and sleeve. The nozzle tube is usually formed with a.n. annular flange for-mounting the nozzle on a tundish or ladle, and the heating element is preferably a cylindrically wound resistance wire.

It will be appreciated that spout nozzles of the invention may be readily dismantled, and indeed provided in modular form. Thus, the ceramic sleeve may be replaced when worn, as can the other components, while the nozzle tube itself may be reused many times.

Spout nozzles according to the invention can be based on a spout system which is suitable for relatively high casting outputs. The clear crosssection can be reduced by the insertion of an interchangeable ceramic sleeve. This sleeve is subject to wear, although the nozzle tube is not.The resistance wire is disposed in the space between the sleeve, which reduces the diameter, and the nozzle tube of the spout nozzle is also protected by the sleeve part and can therefore be reused numerous times.

Spout nozzles according to the invention can define output diameters of, for example, 3 mm, without any risk 11 (1 Z 3 of freezing up, even when the metal in question is steel. Applications include the atomisation of small metal quantities to produce powder or for spray compacting or, if a multiple arrangement is provided and the spout system appropriately formed, casting thin slabs which are between 30 and 80 mm thick in a continuous casting process.

The invention will now be described by way of example and with reference to the accompanying drawings wherein:

Figure 1 shows an elevation and top plan view of a nozzle tube used in one embodiment of the invention; Figure 2 is a longitudinal section through the nozzle tube of Figure 1 with a ceramic sleeve inserted; and Figure 3 is a further longitudinal section through a spout nozzle according to the invention using the nozzle tube of Figure 1.

The cylindrical nozzle tube 11 of Figure 1 has an annular flange 1, which is arranged at the upper end and serves to secure the nozzle to the bottom of a tundish or a ladle. This nozzle tube can be secured in the usual manner to the bottom of a tundish or a ladle, although this is not illustrated in detail here.

A ceramic sleeve 3, which is supported in the upper area by means of a flange 2, for example, can be inserted in this nozzle tube 11 to reduce the teeming cross- section and thus the casting speed. The support may be provided by an annular recess in the flange part 1 of the nozzle tube 11, as shown in Figure 2. Supporting or balancing intermediate rings 4 may alternatively or additionally be used. As explained above, the melt cannot be prevented from freezing if the clear crosssection is reduced further. In order to avoid this, and as shown in Figure 3, the spout nozzle is heated by a resistance wire 10, which is wound in a cylindrical cl, 4 manner and arranged in the space between the inserted sleeve 7 for minimum flow rates and the inner wall of the cylindrical nozzle tube 11. Suitable connections (not shown) for the resistance wire 10 to an external power source will be provided. An insulating disc 8 and an insulating sleeve 9 of, for example, ceramic paper, may also be provided in the upper area. It is clear from the drawing that in the arrangement the actual wearing part is the inserted spout 7, which can be replaced after it has worn, without having to replace the entire spout, including in particular the resistance wire arrangement.

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Claims

1. A spout nozzle for casting metal, for connection to a tundish or ladle, which nozzle comprises a cylindrical nozzle tube; a ceramic sleeve received in the nozzle tube, the outside diameter of the ceramic sleeve being less than the inside diameter of the nozzle tube; and a cylindrical heating element. connectable to an external power source, arranged in the space between the tube and sleeve.

2. A spout nozzle according to Claim 1 wherein the nozzle tube is formed withan annular flange for mounting the nozzle on a tundish or ladle.

3. A spout nozzle according to Claim 2 wherein the ceramic sleeve has at one end an annular flange which is supported in an annular recess in the flange of the nozzle tube.

4. A spout nozzle according to any preceding claim including an insulating sleeve of ceramic paper between the resistance coil and the inner surface of the nozzle tube.

5. A spout nozzle according to any preceding Claim wherein the heating element is a cylindrically wound resistance wire.

6. A spout nozzle for casting metal substantially as described herein with reference to the accompanying drawings.

Published 1990 at The PatentOffice,State House, 66,71 High HolbornLondonWC1R4TP. Further copies maybe obtainedfrom, The Patent Office.