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(11) | EP 0 227 154 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Crystallisers employed for almost horizontal continuous casting Gusskokillen für nahezu waagerechten Strangguss Lingotières utilisées dans la coulée continue pratiquement horizontale |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention concerns a crystalliser employed for almost horizontal continuous casting according to the preamble of claim 1.
[0002] During continuous reasearch to eliminate the faults in blooms and billets leaving the ingot moulds the present applicant has undertaken a thorough investigation into ingot moulds.
[0003] The traditional curved ingot are known from e.g. DE-B-1 025 578, FR-A-1 479 946 and US-A-3 623 533.
[0004] The applicant has led to the conclusion that the ferrostatic pressure in ingot moulds of continuous casting machines and, in particular, in ingot moulds for almost horizontal continuous casting has an increased value on the side having the interior curve of the mould and a reduced value on the side having the exterior curve. In particular, such difference in ferrostatic pressure may even reach 30% in ingot moulds for almost horizontal continuous casting.
[0005] Moreover, the lengthwise contact surface of the exterior curve is greater than that of the interior curve, and such contact surface varies considerably according to the shapes and dimensions. The cooling conditions, therefore, differ as between the interior courve and exterior curve.
[0006] It has also been determined that the contact between steel in its solidification phase and the interior curved side of the ingot mould takes place during a rather short time and causes a relatively small growth of skin, such growth being, in any event, less than that which occurs against the lateral faces and the exterior curved side of the ingot mould.
[0008] This is achieved by a crystalliser of the mentioned type, and having the features disclosed in the claim 1.
[0009] The crystalliser according to the present invention has a suitable taper as between the frace of the interior curve and the face of the exterior curve of the ingot mould in relation to the axis of the casting line.
[0010] In particular, according to the invention, such taper is dissymmetrical as between the interior curved side and exterior curved side of the ingot mould in relation to the axis of the casting line.
[0011] In particular, the taper is greater in the interior courved side and smaller in the exterior curved side, depending on the degree to which the machine is positioned below the horizontal, such degree being defined by the angle between the horizontal and the raduis of curvature of the casting line running from the centre of curvature to the top of the ingot mould. The lateral faces of the ingot mould retain their normal taper.
[0012] According to the invention, therefore, the crys- tallisers possess on their exterior curved side, in relation to the axis of the casting line understood as being the lengthwise axis of the ingot mould with a constant curvature, a taper which is less than or, at the most, the same as those of the exterior curved sides of known embodiments.
[0013] Such taper is preferably be nil, that is to say, in a preferred embodiment the exterior curved side has the same curvature as the axis of the casting line.
[0014] The lateral faces of the mould are embodied as at present, whereas the inner curved side is provided with an increased taper, which varies progressively until it reaches a value which may even be twice the normal value.
[0015] The attached figures are given a non-restrictive example and illustrate the following:-
Fig. 1 shows a diagrammatic casting line that makes plain the lay-out of the invention;
Fig. 2 shows a traditional crystalliser for almost horizontal continuous casting and a crystalliser according to the invention for such type of casting.
Fig. 1 shows a continuous casting ingot mould 10 for almost horizontal continuous casting. The axis of the casting line 17 possesses a constant curvature; the angle providing the degree to which the continuous casting is performed below the horizontal is indicated with "alpha".
Fig.2 shows a comparison between the geometry of a traditional crystalliser and the geometry of the crystalliser of the invention.
[0016] An ingot mould or crystalliser 10 in its traditional form has a conformation according to the lines A and C; the interior curved side is referenced with 11, the exterior curved side with 12 and the lateral faces with 15.
[0017] The inlet and outlet are referenced with 13 and 14 respectively, while 16 is the level of molten material.
[0018] In this embodiment, whereas the taper of the exterior curved side is substantially reduced progressively (depending on the angle "alpha" of the degree to which the machine is positioned below the horizontal; please see Fig.1), the taper of the interior curved side is substantially increased by an equal value.
[0019] Such tapers are respectively those of the interior curved side and exterior curved side in relation to the axis 17 of the casting line.
[0020] The actual line of the interior curved side according to the invention, therefore, takes up a development according to the conformation B instead of the conformation A whereas the exterior curved side in turn takes up a development according to the conformation D instead of the conformation C.
[0021] In this way, if it is desired to convert a traditional ingot mould or crystalliser into an improved crystalliser, the taper which is created progressively between the interior curved side 111 and casting line axis 17 is increased, whereas the taper between the exterior curved side 12 and casting line axis 17 becomes progressively reduced or even becomes nil.
1. Crystallizer (10) employed for almost horizontal continuous casting, the starting
zone of which is curved by a predetermined constant curvature defined by an axis (17)
of curvature corresponding to an arc of a circle, said crystallizer (10) comprising
two lateral walls (15) having flat surfaces and an external wall (12) and internal
wall (11) having curved surfaces, said external wall (12) and internal wall (11) of
said crystallizer (10) being tapered towards said axis (17) of curvature, characterised
in that the taper between said curved internal wall (11) and curved external wall
(12) of said crystallizer (10) towards said axis of curvature is dissymetrical.
2. Crystallizer (10) according to claim 1, characterised in that the taper of the
internal wall (11) relative to the axis (17) is greater than the taper of the external
wall (12) relative to said axis (17).
1. Kristallisator (10), der zum fast horizontalen Stranggießen verwendet wird, dessen
Anfangsbereich gemäß einer vorbestimmten konstanten Krümmung gekrümmt ist, die durch
eine Krümmungsachse (17) entsprechend einem Kreisbogen definiert ist, wobei der Kristallisator
(10) zwei seitliche Wände (15) mit ebenen Oberflächen und eine äußere Wand (12) und
eine innere Wand (11) mit gekrümmten Oberflächen aufweist und die äußere Wand (12)
und die innere Wand (11) des Kristallisators (10) zu der Krümmungsachse (17) hin zulaufen
dadurch gekennzeichnet, daß das Zulaufen zwischen der gekrümmten inneren Wand (11)
und der gekrümmten äußeren Wand (12) des Kristallisators (10) zu der Krümmungsachse
hin unsymmetrisch ist.
2. Kristallisator (10) nach Anspruch 1, dadurch gekennzeichnet, daß das Zulaufen der
inneren Wand (11) bezüglich der Achse (17) beträchtlicher ist als das Zulaufen der
äußeren Wand (12) bezüglich der Achse (17).
1. Cristalliseur (10) utilisé pour la coulée continue presque horizontale, la zone
de démarrage de celui- ci étant incurvée suivant une courbure prédéterminée constante
définie par un axe de courbure (17) correspondant à un arc de cercle, ledit cristalliseur
(10) comprenant deux parois latérales (15) ayant des surfaces plates et une paroi
extérieure (12) et une paroi intérieure (11) ayant des surfaces incurvées, ladite
paroi extérieure (12) et ladite paroi intérieure (11) dudit cristalliseur (10) présentant
une obliquité vers ledit axe (17) de courbure, caractérisé en ce que l'obliquité entre
ladite paroi incurvée intérieure (11) et la paroi extérieure incurvée (12) dudit cristalliseur
(10) vers l'axe de courbure est dissymétrique.
2. Cristalliseur (10) selon la revendication 1, caractérisé en ce que l'obliquité
de la paroi intérieure (11) par rapport à l'axe (17) est plus grande que l'obliquité
de la paroi extérieure (12) par rapport à l'axe (17).