AU618836B2

AU618836B2 - Lateral wall for an installation for continuous casting between movable walls, installation possessing this wall and suitable process for the continuous casting of thin metal products

Info

Publication number: AU618836B2
Application number: AU40025/89A
Authority: AU
Inventors: Paul Victor Riboud
Original assignee: Institut de Recherches de la Siderurgie Francaise IRSID
Current assignee: Institut de Recherches de la Siderurgie Francaise IRSID
Priority date: 1988-09-14
Filing date: 1989-08-17
Publication date: 1992-01-09
Anticipated expiration: 2009-08-17
Also published as: JPH02112853A; FR2636259A1; AU4002589A; ZA896489B; DD297348A5; CN1041123A; RU1782189C; EP0360635A1; BR8904579A; CN1018242B; DD284619A5; FR2636259B1; KR900004434A

Description

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AUSTRALIA

PATENTS ACT 1952 Form COMPLETE SPECIFICATION (ORIGINAL) lq FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: SPublished: Priority: Related Art: 1 1f TO BE COMPLETED BY APPLICANT Name of Applicant: INSTITUT DE RECHERCHES DE LA SIDERURGIE FRANCAISE (IRSID) SAddress of Applicant: IMMEUBLE ELYSEES-LA-DEFENSE 19, LE PARVIS LA DEFENSE 4 92800 PUTEAUX

FRANCE

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, S* Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: LATERAL WALL FOR AN INSTALLATION FOR CONTINUOUS CASTING BETWEEN MOVABLE WALLS, INSTALLATION POSSESSING THIS WALL AND SUITABLE PROCESS FOR THE CONTINUOUS CASTING OF THIN METAL PRODUCTS.

The following statement is a full description of this invention including the best method of performing it known to me:- 1A.

GRA 845 LATERAL WALL FOR AN INSTALLATION FOR CONTINUOUS CASTING BETWEEN MOVABLE WALLS, INSTALLATION POSSESSING THIS WALL AND SUITABLE PROCESS FOR THE CONTINUOUS CASTING OF THIN METAL PRODUCTS The present invention relates to an installation for the continuous casting of thin metal products, especially steel, between movable walls, especially between rolls, and more particularly the lateral walls commonly known as "side walls delimiting the casting space in the vicinity of the lateral edges of the said movable walls.

A problem common to the various types of installation for continuous casting between movable walls is to close off in a sealed manner the lateral ends of the casting space located between the movable walls.

Another problem is to prevent the cast metal from clinging to the lateral walls, this clinging risking causing breakouts at the edges of the cast product.

Yet another problem is to prevent the formation of a solidified wedge in contact with these walls above the neck, that is to say the narrowest passage point between the movable walls.

To solve these problems, it has already been proposed to use thermally insulating lateral walls, in order to limit the solidification initiated in contact with them and thus prevent the formation of the said wedge. A device of this ~ty i describ~ed particularly in rLL 2. V ~IL -0 023* in the name of the proprietor of the present application.

It is also known, especially from the documents US 303 8219 and EP 212 423, to arrange the lateral walls with a relief angle that is to say their surf aces diverge symmetrically from one another towards the neck. In particular, this arrangement allows the lateral expansion of the product in proportion as it approaches the neck, this expansion being caused by the rolling effect of the S wedge prematurely solidified or in the process of solidi- %fication.

-2- However, these arrangements do not make it possible to prevent infiltrations of liquid metal between the lateral walls and movable walls, solidification being only inadequately controlled in this region. In fact, if the lateral wall is sufficiently insulating to prevent the solidification of the cast metal in contact with it, liquid metal can infiltrate in the region of the lateral-wall/movable-wall junction. Furthermore, the materials used to produce these highly insulating lateral walls usually have only little mechanical resistance. They therefore experience rapid wear as a result of the friction of the metal and of the ends of rolls, and this further assists the infiltrations.

Conversely, if the lateral walls are less insulating, the cast metal solidifies in contact with them, but since this solidification is difficult to control problems of wedging, clinging or irregularity of the edges of the product can still persist, even when the lateral walls have a relief angle.

The object of the present invention is to overcome the abovementioned disadvantages and assist cooling over the entire width of the cast product, especially at the edges of its large sides, but without bringing about premature solidification in contact with lateral walls.

With these aims in view, according to the present invention there is provided a lateral wall for an apparatus for the continuous casting of metal products, especially thin products, between movable walls, the apparatus comprising two mutually confronting cooled movable walls driven simultaneously in the same direction 4) and delimiting with two of the said stationary lateral walls a casting space, 3 characterized in that the lateral wall comprises a closing plate retained against the end faces of the movable walls 2) and two inserts 8) made of a material of high thermal conductivity which penetrate into the casting space between the movable walls adjacent to the edges (11) of the said movable walls and in the vicinity of the neck between the movable walls, the inserts delimiting between them a zone consisting of a covering made of thermally insulating material the surface (91) of which is plane or concave, and each insert having a face (73, 83) directed towards the casting space.

By means of thu device according to the invention, the solidified metal skin in contact with the cooled movable walls extends onto that face of the inserts directed towards the casting space. The continuous skin obtained covers the join between the movable wall and inserts, thus preventing infiltrations S* of liquid metal there. Moreover, no skin forms in contact with the inter-insert zone of the lateral walls, since this is highly insulating.

According to a special arrangement of the invention, the faces of the inserts directed towards the casting space and the surface of the insulating covering are substantially disposed at a relief angle. In this arrangement, the relief angle of the lateral walls allows the lateral expansion of the edges of the cast product. A the same time, the edges of the skin which form in contact with the inserts are progressively laid against the movable walls by mens of the ferrostatic pressure.

According to another complementary arrangement, the said faces of the inserts confronting the casting space are also inclined relative to a vertical plane perpendicular to the movable walls, this inclination

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3a decreasing progressively from the upper end to the lower end of the inserts, where their said faces confronting the casting space are substantially perpendicular to the movable walls.

In this case, the effect of the progressive laying of the edges of the solidified skins is increased further, these solidified skins widening and thickening progressively so as to form, near the region of the neck, two skins of a thickness substantially constant over the entire width of the product.

This special arrangement makes it possible, in particular, to minimize the forces exerted on the walls

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of the rolls perpendicularly relative to these.

In fact, if, from the level of the liquid metal, solidification of the edges of the skin forms tongues perpendicular to the wall of the roll, these tongues tend to thicken as they approach the neck and the ferrostatic pressure can be insufficient to lay them uniformly against the cooled walls of the rolls, thus giving rise to irregularities of solidification and also a higher force near the neck where the tongues meet and tend to be "rolled".

Furthermore, if these tongues are not properly laid against the cooled walls, sealing between the roll and the lateral wall is no longer ensured, and liquid metal risks infiltrating between the tongue and the 15 adjacent lateral wall. The risk is virtually eliminated as a result of the special arrangement mentioned above.

Another subject of the invention is an installation for the continuous casting of thin metal products between movable walls, especially between rolls, this installation being characterized in that it possesses lateral walls according to one of the above mentioned arrangements.

Yet another subject of the invention is a process for the continuous casting of thin metal products, especially steel strips of small thickness, according to which the above installation is used, the casting space is fed with liquid metal, its level being kept below the upper end of the inserts and of the insulating covering, the movable walls are driven simultaneously and in the same direction, as a result of which the liquid metal solidifies in contact with the said cooled movable walls, thereby forming solidified skins, the edges of which extend onto those surfaces of the inserts directed towards the casting space, these skins widening and thickening in proportion to the movement of the movable walls, until they meet near the region of the neck between the said movable walls, and the solidified thin metal product is extracted continuously in the downward direction.

LI t I I The invention will be understood better and other characteristics and advantages will emerge from a reading of the following description of a preferred embodiment of the invention, in the instance of casting between rolls.

Reference will be made to the accompanying drawings in which: Figure 1 is a partial diagrammatic representation of an installation for continuous casting between rolls, showing the arrangement of a lateral wall according to the invention; Figure 2 is a sectional view in the plane II- II of Figure 1; 61 Figures 3 to 6 are diagrams showing the change in the solidification of the product at the various 6645 levels indicated in Figure 2; Figure 7 is a plan view of a lateral wall aaat specially designed for a casting apparatus according to the invention; Figure 8 is a view of this wall in vertical 20 section along the line VIII-VIII of Figure 7; a .a Figure 9 is a sectional view of this wall along the line IX-IX; Figure 10 is another view in horizontal sectior according to X-X of Figure 7.

The diagrammatic drawings of Figures 1 to 6 are given purely for purposes of information and it will be appreciated that the relative dimensions of the various elements have deliberately not been adhered to, in order to make it easier to understand the subject of the invention and the aims in view.

Figure 1 illustrates one end of an installation for continuous casting between rolls, comprising two rolls 1 and 2, the second of which has been symbolized merely by the line 21 of the end of its wall.

The two rolls of parallel axes and arranged in the same horizontal plane P are driven in rotation in opposite directions according to the arrows 3 and 4 and in the region of the neck 5, corresponding to the level of the plane P passing through the axes of the rolls, are -6spaced at a distance corresponding to the thickness of the cast product.

SLiquid metal is fed, by one of the well known methods, into the casting space delimited on the one hand, by that part of the walls of the rolls located above the neck and, on the other hand, by the lateral walls located at the edges of the rolls and in sealing contact with the said edges. It is clear that, since the lateral walls are stationary and the walls of the rolls 1 0 are movable, a minimum functional play must be maintained between these, in order to prevent intense friction and the wear which would occur as a result of this. Conser quently, sealing cannot be absolute and there is the risk that infiltrations of liquid metal will occur. In par- 15 ticular, reducing the risk of infiltrations is one of the aims of the present invention.

In fact, if, as mentioned at the start of this i specification, the lateral wall consists of a material sufficiently insulating to ensure that the liquid metal does not solidify in contact with it, the solidified metal skin in contact with the cooled walls of the rolls stops just at the join between the lateral wall and the roll, and the risk of infiltration in this region is Shigh.

The idea governing the present invention is specifically to ensure sealing relative to the liquid metal by assisting the extension of the solidified skin onto that part of the lateral wall directly adjacent to the rolls, whilst at the same time making it easier to shape the edges of these skins and preventing the solidification of the metal in contact with the lateral walls.

Consequently, the solidified skin covering the join between the roll and lateral wall forms a sealing wall preventing infiltrations.

Figure 1 shows a lateral wall or side wall 6, consisting of a vertical plane plate 61 held with a functional play against the ends of the rolls 1 and 2, that is to say against the end faces of the cylindrical surfaces of these. This plate 61 carries two inserts 7, -7- 8 made of a material of high thermal conductivity. Each insert is a lamella of small thickness, preferably in the neighbourhood of half the thickness of the casting product, bent according to the curvature of the rolls, and projects from the plate 61 towards the inside of the casting space so as to mate with the edge 11 of the cylindrical wall. The lower ends 71, 81 of the inserts of a same lateral wall meet at a level preferably located slightly above the neck 5. The width of the inserts projecting from the plate 6 decreases uniformly from their upper ends 72, 82 to their lower ends 71, 81. That face 73, 83 of the inserts confronting the casting space is, at any level, inclined relative to the generatrix of the roll located at this level, this inclination increas- ~ing progressively from the upper ends of the inserts towards their lower ends where it is in the neighbourhood ear.

of 90'. In other words, the face 73, 83 of each insert is a skew surface, a horizontal generatrix of which forms an obtuse angle of, for example, approximately 135' with the corresponding generatrix of each adjacent roll at the 04t upper end 72, 82, this angle decreasing progressively downwards until it is substantially equal to 900 at the ealower end.

4 The zone located between the inserts of the same side wall consists of a plate or of a covering of insulating refractory material 9, of which the surface 91 confronting the casting space is preferably plane and inclined relative to the vertical, to form the relief angle already mentioned and clearly visible in Figure 2, so as to produce a continuous surface with the faces 73, 83 of the inserts, without roughnesses at their joining lines.

Advantageously, the refractory material 9 is hardened at the surface, to prevent too rapid wear by the cast metal.

It will be appreciated, of course, that, during the casting, the level of liquid metal must be maintained below the upper limit of the inserts and of the refractory material.

As indicated in Figure 2, the lower ends of the inserts can form an abrupt setback 62 relative to the I_ i _ia 8a:c~~c i*~C19 ~-ii- 8 plate 61, similar to that shown in 4he document EP 212 423 already mentioned, and this allows the free lateral expansion of the edges of the cast product in the region of the neck. However, as will be described in more detail later in this specification, it will be preferable to ensure continuity between the surfaces of the inserts 73, 83 and of the refractory material 91 and the wall portion 63 immediately below.

The faces 73, 83 of the inserts can also be plane in the same plane as the surface 91 of the insulating r refractory material 9, thereby simplifying the production of the said inserts. Continuity of the solidified skin in the region of the join between the rolls and inserts is also ensured. However, this arrangement is less conducive to the formation and the desired change of the said skin, according to the description which will be made with reference to Figures 3 to 6.

These figures show horizontal sections for the casting installation, during casting, at the various levels identified in Figure 2.

Figure 3 shows diagrammatically a section at level III near the level N of the liquid metal. The molten metal 10, in contact with the cooled walls of the rolls 1 and 2, solidifies and forms a solidified skin of small thickness 101, 102 on each roll. This skin is extended by a tongue 103, 104 solidified in contact with the inserts 7, 8 which are thermally conductive and which i are cooled because of their proximity to the cooled walls Sof the rolls and contact with the metal mass of the plate 61. In contrast, the cast metal does not tend to solidify in contact with the insulating refractory material 9. It will be seen that the solidified skin ensures sealing from the upper level in the region of the point 105, 106 between the rolls and inserts.

Figure 4 is a section at the intermediate level IV when the skin 101, 102 reaches this level by being driven by the walls of the rotating rolls. At the same time, the tongues 103, 104 accompany this movement by sliding on the faces 73, 83 of the inserts.

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*Ir 44 The cooling of the cast metal continues and the thickness of the skin 101', 102' and of the tongue 103', 104' increases. The width of the face 73, 83 of each insert is reduced because of the increase in its inclination relative to the wall of the roll. At the same time, the width of contact of the solidified skin with the roll increases because of the clearance of the lateral wall, and the tongue is laid proportionately against the wall of the roll under the effects of the ferrostatic pres- 10 sure. Because of the relief angle. of the surface 91 of the refractory 9, the casting space widens.

At level V of the lower end of the inserts (Figure the thickness of the skin 101", 102" has increased further. The two tongues formed on each insert are laid against the walls of the rolls and at the same time meet at 108.

In the region of the neck (level VI, Figure 6), the two skins are in complete contact and form the product 109 of desired cross-section, and the lateral expansion of the edges caused by the rolling effect is allowed by the final increase in width of the casting space, until contact is made with the wall portions 63.

As will have already been understood, the apparatus according to the invention: makes it possible to ensure the sealing of the casting space, allows the lateral expansion of the product, controls the formation and change of the solidified skin and, above all, of its edges (tongues), whilst preventing the formation of a solid skin on the lateral walls.

Figures 7 to 10 illustrate a preferred embodiment of a side wall.i. according to the invention.

In this embodiment, the plate 61 consists of several elements assembled by screwing, so as to make it possible to hold the inserts 7, 8. It comprises a plane support plate 64, to which are fastened by means of screws 111 and retained in position by means of centering studs 112 two bearing plates 65., 66, the plane surface of 10 which is intended to be placed opposite the ends of the rolls and shaped so as to have a curved edge 67, 68 of the same radius of the rolls and inscribed exactly within the extension of these.

The metal inserts 7, 8 are laid against the curved edges 67, 68 and in contact with the support plate 64. They are held in position by means of studs 74 which are fastened in the bearing plates 65, 66 and which .penetrate into oblong holes 75 made in the inserts, in 0 order to prevent these from moving in the direction parallel to the axis of the rolls, whilst at the same u time allowing a slight movement parallel to the edges of the bearing plates, to permit the longitudinal expansion of the said inserts.

The thickness of the inserts is constant (for example, 2 mm). Their width varies from their upper ends, where they project from the plane of the surface of the bearing plates a few millimetres (for example 5 to S mm), to their lower ends, the projection is markedly less (for example 1 to 2 mm). These values are given only as an indication and depend particularly on the general dimensions of the installation. These values correspond to a relief angle of the inserts and also of a refractory covering of the order of 1 to 30. The faces 73, 83 of the ll inserts 7, 8 are shaped as mentioned above, so as to have a uniform variation of their inclination relative to the wall of the rolls. The inserts therefore have, at their upper ends, a bevelled cross-section of an angle in the neighbourhood of 45, this angle increasing downwards until, at the lower end, it forms a quadrangular crosssection.

A metal intermediate plate 69, two sides of which are shaped according to the curvature of the inserts, is inserted between these, in order to keep them laid against the curved edges 67, 68 of the bearing plates 66. The intermediate plate 69 is fastened to the support plate 64 by means of screws 113.

The intermediate plate 69 has a smaller thickness than the bearing plate 65, 66, in order to make it II(IIIC II)CI) C I*CI~CIC CI 11 possible to place against this plate 69 and between the j inserts an insulating refractory material 9, of which the face 91 confronting the casting apace is flush with the faces 73 and 83 of the inserts. This insulating material can be a prefabricated plate bonded to the intermediate plate 69, or it can be a material deposited in place, for example by spraying.

The lower ends of the inserts of the intermediate plate 69 and of the insulating refractory covering 9 are 0 located at the sime level, slightly above the neck. At this level, the lower ends of the inserts are spaced slightly, in order to preserve some width at the "tip" of the insulating refractory material, so as to prevent embrittlement of this tip.

Below this level (corresponding to level V of Figure the lateral wall is extended by a guide shoe 120 fastened to the support plate 64 by means of screws .114. The rear part 121 of the guide shoe is inserted in 2. corresponding recesses 122, 123 made in the bearing 4 44 plates 65, 66. The front part 124 of the guide shoe is machined so as to have end faces 125, 126 of a curvature corresponding to that of the edges 67, 68 of the bearing plate 65, 66. That face of this guide shoe confronting the cast product possesses, above the neck, a relief zone 127 in the extension of the face 91 of the refractory covering 9 and, below the neck (at the level of the plane a vertical plane zone 128 located in the same plane as the surface of the bearing plates 65, 66.

6 The guide shoe 120 is produced from a material having good characteristics of wearing resistance, for example cast iron.

The advantage of the special configuration of the guide shoe 120 just described, particularly as regards the gelief zone 127, in relation to the setback 62 shown in Figure 2 is that it ensures the continuity of the lateral wall in contact with the cast product and thus prevents too rapid wear or a breakaway of the lower ends of the inserts and of the refractory covering.

Of course, the invention is not limited to the i. -i 12 embodiment described above by way of example. Technological modifications can be made to the various component elements of the lateral wall and to the method of assembling them.

For example, the inserts can be produced from a material not solely metallic, such as compounds of the type of boron nitride, BN with SiALON or SiN 4 or AlN or also SiC.

It is also possible for the face 91 of thp refractory covering to be concave instead of plane.

It is also possible for the inserts to penetrate further forwards between the rolls, in such a way that the guide shoe likewise penetrates between these and therefore protrudes relative to the bearing plates.

The formation of the tongues of the solidified skin can also be assisted by means of a device for the localized cooling, near the inserts, of the bearing c* plates and/or of the support plate and also of the shoe or by a direct cooling of the inserts.

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Claims

1. Lateral wall for an apparatus for the continuous cascing of metal products, especially thin products, between movable walls, the apparatus comprising two mutually confronting cooled movable walls driven simultaneously in the same direction 4) and delimiting with two of the said stationary lateral walls a casting space, characterized in that the lateral wall comprises a closing plate retained against the end faces of the movable walls 2) and two inserts 8) t made of a material of high thermal conductivity which penetrate into the casting space between the movable walls adjacent to the edges (11) of the said movable .walls and in the vicinity of the neck between the .movable walls, the inserts delimiting between them a zone consisting of a covering made of thermally insulating material the surface (91) of which is plane or concave, and each insert having a face (73, 83) directed towards the casting space. i

2. Lateral wall according to claim 1, ii characterized in that those faces (73, 83) of the inserts directed towards the casting space and the surface (91) of the insulating covering are substantially disposed at a relief angle.

3. Lateral wall according to one of claims 1 U and 2, characterized in that the said faces (73, 83) of the inserts confronting the casting space are also inclined relative to a vertical plane perpendicular to the movable walls, this inclination decreasing progressively from the upper ends (72, 82) to the lower ends (71, 81) of the inserts, where the said faces (73, 83) are substantially perpendicular to the movable walls. 14

4. Lateral wall according to claim 2, characterized in that the relief angle is 1 to 3 degrees.

Lateral wall according to claim 3, characterized in that the inclination of those faces (73, 83) of the inserts confronting the casting space, at the upper end, is 135 degrees relative to the generatrix of the adjacent movable wall.

6. Lateral wall according to one of claims 1 to characterized in that it possesses, below the inserts and the refractory covering and adjacent to their lower ends, a shoe (120), of which the surface confronting the casting space has, above the neck a relief zone (127) in the extension of the surfaces (91, 73, 83) of the inserts and of the refractory covering and, below the neck a vertical plane zone (128).

7. Installation for the continuous casting of :thin metal products between movable walls, especially between rolls, characterized in that it comprises lateral walls according to one of claims 1 to 6.

8. Process for the continuous casting of thin metal products, characterized in that the installation according to claim 7 is used, the casting space is fed J with liquid metal, its level being maintained below the upper end of the inserts and of the insulating covering, the movable walls are driven simultaneously and in the same direction, as a result of which the liquid metal solidifies in contact with the said cooled movable walls, forming solidified skins, the edges of which extend onto those surfaces of the inserts directed towards the casting space, these skins widening and wvpx 15 thickening in proportion to the movement of the movable walls, until they meet in the vicinity of the region of the neck between the said movable walls, and the solidified thin metal product is extracted continuously in the downward direction.

9. Lateral wall substantially as hereinbefore described with reference to the accompanying drawings. Installation for the continuous casting of thin metal products substantially as hereinbefore described with reference to the accompanying drawings. S11. Process for the continuous casting of thin metal products substantially as hereinbefore described with reference to the accompanying drawings. *o*j Dated this 9th day of October 1991 INSTITUT DE RECHERCHES DE LA SIDERURGIE FRANCAISE (IRSID) By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia. I