Continuous casting of flat products today is a mature technique for production of steel semis with an as‐cast thickness of 200 mm. At present, the thin slab casting is developed to the extent of casting and in‐line rolling of strips with a thickness of 1–2 mm. Up to now, it is reported that 27 thin slab production lines are under construction or in operation. The strip‐casting technique is the next generation of production lines for steel to be developed for production of flat products. There are 2 main directions in the development of strip casting. The 1st is the twin roll casting technique, which so far has concentrated its efforts on production of stainless steel strips. The 2nd is the single‐belt casting technique (DSC – Direct Strip Casting) which is aiming for high production volumes of flat products with the necessary hot reduction possibility to receive good material properties.The development of strip casting at MEFOS started in the late 80s with the joint efforts of a Nordic group of steel companies. The aim of the project was to built up know‐how in the field of strip casting by the erection and operation of a strip caster at MEFOS. After a 1‐year prestudy, the single‐belt casting technique was chosen. The German machine‐building company, Mannesmann Demag Metallurgy, and the Nordic consortium had complementary interests, and in 1991, a co‐operation agreement was signed in the field of strip casting. At MEFOS, the emphasis is focused on the industrial application of casting 870 mm wide strips, while the focus of the development at Technical University of Clausthal (TUC) is devoted to casting and in‐line rolling. Based on the potential of the process and the promising results obtained in the research facilities, the industrial partners are now in the position to decide on building a demonstration caster in a steel plant.
Within the framework of research investigations described in this paper, a measuring method for the determination of heat transfer coefficients in the range of stable film boiling has been developed for water spray cooling in the secondary cooling zone of continuous casting machines. Based on investigations by 3), a water cooled test sample with a measuring field of 20 × 20 mm2 was constructed. For this sample geometry, a special evaluation method has been developed which permits quick evaluation in on‐line procedure. Result of measurements are sections for the heat transfer coefficient arising from different spray water distributions. On the one hand, these can be used as calculation figures for the determination of the solidification profile and the solidification rate. On the other hand, the measuring results serve as an assessment basis for nozzle constructions. Practical use of the measuring results confirms the usefulness of the measuring method on a laboratory scale. In addition, the validity of the measuring results has been demonstrated by comparing them with an unsteady state method in accordance with 2).
In dem vorliegenden Forschungsbericht wurde der Frage nachgegangen, unter welchen Voraussetzungen ein dynamisches Abdichten des Spaltes zwischen einer waagerecht liegenden Duse und beweglichen Kokillenwiinden gegenuber eindringendem Metall in einer GieBanlage mit mitlaufender Kokille rnoqlich ist. Dazu wurde ein mathematisches Modell entwickelt, welches das thermische und hydrodynamische Gleichgewicht zwischen in den Spalt einstromendern flussiqern Metall und abstrornendern Erstarrten beschreibt. Es wird deutlich, daB immer flussiqes Metall in den Spalt einstrornt, Wie weit dieses jedoch einflieBt, hiingt fur Stahl hauptsiichlich von den Parametern GieBgeschwindigkeit und Wiirmedurchgangswiderstand zwischen dem Erstarrten und der Kokillenoberfliiche abo Wird insbesondere eine gute Wiirmeabfuhr an die Kokillenwiinde erzielt, so kann die Eindringtiefe dieselbe Grolsenordnunq wie die Spalthohe annehmen. Daruber hinaus wurde abgeschiitzt, unter welchen Voraussetzungen Schwingungen der Eindringtiefe durch OberfliichenspannungseinfluB auftreten konnen, Diese mit dem OberfliichenspannungseinfluB berechneten Eindringtiefen sind jedoch kleiner als diejenigen, die mit Hilfe des mathematischen Modells ermittelt wurden. Dieses Hefert folglich Werte, die man als "nach oben hin abgeschiitzt" bezeichnen kann. Mit Hilfe des vorgestellten mathematischen Modells liiBt sich zeigen, daB die dynamischeAbdichtung eines Spaltes zwischen Duse und sich bewegender Kokillenwand rnoqlich ist. Dabei weisen die Ergebnisse GroBenordnungen auf, die technisch zu realisieren sind.Mathematical model of dynamic sealing during pouring and simultaneous solidification of steel in a travelling mould. This research report investigates the conditions required to achieve a dynamic sealing against the inflowing metal of the gap between a horizontal nozzle and the moving mould walls in a casting plant with travelling mould. A mathematical model describing the thermal and hydrodynamic equilibrium between the metal flowing into the gap and the outflowing solidified metal has been developed to this end. It becomes obvious that liquid metal will always flow into the gap. However, the extent of this inflow depends in the case of steel mainly on the parameters casting rate and heat transmission resistance between the solidified metal and the mould surface. Particularly if a good heat transmission to the mould walls is ensured, he penetration depth can be of the same order of magnitude as the gap height. It has been estimated, furthermore, under which conditions fluctuations of the penetration depth can occur under the effect of surface tension. These penetration depths calculated on the basis of the surface tension effect are, however, smaller than those determined by using the mathematical model. Consequently, one may consider the values obtained with the mathematical model as being "overestimated". The mathematical model discussed reveals the possibility of dynamically sealing the gap between nozzle and moving mould. The results obtained feature an order of mag...
The first part of the present paper explains that the cooling methods of the individual casting processes such as link‐type moulds with purely capacitive cooling (e.g. caster‐aluminium casting), with spray water cooling involving the Newtonian cooling characteristic (e.g. continuous casting) and also the combination of both types (e.g. Hazelett belt) can be described as borderline cases of a uniform model. In the second part the temperature distributions in the belt mould (for instance, for evaluating the mechanical strength of the belt) and in the solidified material are discussed in greater detail so that belt mould inside and outside surface temperatures can be detected. The third part of this paper shows the influence of various cooling conditions (e.g. different heat‐transfer coefficient) and the influence of an insulating layer between belt mould and thin slab on the temperature profiles and on the increase of the solidification thickness as a function of the casting path. In the fourth and last part, the dimensional equations of this paper are made dimensionless with the objective of having the possibility of a comprehensive representation.
For the near-net-shape casting of thin steel strips a liquid steel feeding system is developed. This article at first describes the development of a water model for the complete casting machine (cold tests). In this model the control concept for the low-pressure tundish is designed and tested. As a subsequent stage to the water model trials, the functional ability of the casting machine concepts, and particularly to the tundish concepts, is verified in separately conducted tundish tests and also in strip casting trials (hot tests).Anwendbarkeit eines isokinetischen Stahlschmelzenaufgabesystems zum endabmessungsnahen GieBen dOnner Bander. Zum endabmessungsnahen GieBen von dOnnen Stahlbandern ist ein Schmelzenaufgabesystem entwickelt worden. 1m folgenden wird zunacnst Oberdie Entwicklung eines Wassermodells fOr die gesamte GieBmaschine berichtet, in dem das Regelkonzept fOr das Unterdruckverteilersystem entworfen und erprobt worden ist. Aufbauend auf den Wassermodellversuchen ist dann die FunktionstOchtigkeit des GieBmaschinenund speziell Verteilerkonzeptes sowohl in zunachst separat durchgefOhrten Verteilerversuchen als auch in ersten BandgieBversuchen nachgewiesen worden.
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