EP0552124A1 - Twin roll casting machine for casting a metallic product - Google Patents

Abstract

The casting machine includes two contrarotating rolls (1, 2) with parallel axes and two fixed lateral walls (4) bearing on the axial ends of the rolls (1, 2), delimiting a casting space (3) between the rolls (1, 2). Each of the lateral walls (4) includes two plates (5, 6) which are each in frictional contact with a plane front face of one of the rolls (1, 2) and at least one complementary wall (9, 10) inserted between the two plates (5, 6) and between the rolls (1, 2). The rolls (1, 2) include, on their front faces, an annular groove (19, 20) whose axis is the axis of the roll, in a zone in contact with a plate (5, 6). A lubricant is introduced into the groove (19, 20). The metal plates (5, 6) preferably include an annular rib (23, 24) engaged in the groove (19, 20), ensuring the radial positioning of the plates (5, 6). <IMAGE>

Description

The invention relates to a device for continuous casting between cylinders of a metallic product. More specifically, the invention relates to means allowing the maintenance and / or lubrication of the side walls of the continuous casting device delimiting the casting space between the cylinders.

There are known devices for continuously casting a metal product and in particular a thin metal strip comprising two counter-rotating cylinders with horizontal and parallel axes arranged opposite with a spacing corresponding to the thickness of the product to be cast.

The liquid metal is poured into a pouring space defined by the portions of the surfaces of the cylinders situated above a plane passing through the parallel axes of these cylinders and by fixed end side walls called small faces bearing on the axial ends of the cylinders.

The small faces must be applied against the axial ends of the cylinders, so as to obtain an effective seal to prevent any leakage of molten metal.

It is also necessary to avoid or limit the solidification of the metal in contact with the side walls.

To avoid solidification of the metal in contact with the side walls, it has been proposed to produce these walls in a thermally insulating material, so as to prevent the cooling of the molten metal in contact with the side walls.

However, it has proven to be very difficult to obtain both good thermal insulation characteristics and sufficient mechanical strength of the walls. In particular, the wear resistance of the insulating walls is generally insufficient to ensure a long casting time without changing the walls.

It has therefore been proposed, for example in French patent application 90-11000, to use side walls comprising a part of thermally insulating refractory material inserted between the cylinders and placed between two metal plates in the form of disc portions having an edge of frustoconical shape, in rubbing contact each with a flat front face of the cylinder.

The metal plates have an edge of circular shape on each of their faces delimiting the large base or the small base of the frustoconical edge of the plate, due to the frustoconical shape of the edge of the plate. The face comprising the edge of greatest radius of curvature delimiting the large base is placed in contact with a cylinder, so as to be superimposed on the edge of the cylinder. In this way, the liquid metal filling the casting space comes into contact, at the level of the small faces, only with the pieces of insulating refractory material interposed between the metal plates.

It is therefore necessary to maintain the metal plates in a perfectly defined position relative to the cylinders, during the entire casting, taking into account the fact that the cylinders are liable to expand radially and in the direction of their axes or else to spread or approach in radial directions.

In addition, it may be difficult to obtain perfect alignment of the front faces of the two cylinders, due to the precision of adjustment and machining of the cylinders.

Finally, it may be difficult, before starting the casting device, to adjust the small faces, so that the edges of the metal plates of these faces are in perfect coincidence with the edge of the cylinders.

On the other hand, the fact that the metal lateral parts of the small plate-shaped faces are in rubbing contact with the cylinders generally requires the introduction of a lubricant between the rubbing surfaces, to limit their wear.

It has been proposed to introduce the lubricant which may consist of grease in cavities machined in the metal parts of the small faces. This method of proceeding has a drawback in that the cavities which may be formed by grooves are produced on a consumable part which must be replaced after a relatively short time of use.

In addition, the metal parts of the small faces are not effectively maintained and centered relative to the cylinders.

The object of the invention is therefore to propose a device for the continuous casting of a metallic product comprising two counter-rotating cylinders with parallel axes arranged opposite each other with a certain spacing and two fixed lateral walls, or small faces, in abutment on the axial ends of the cylinders, delimiting a casting space between the cylinders and each comprising two plates which are in rubbing contact each with a flat front face of one of the two cylinders at one of the axial ends of the cylinders and a wall complementary inserted between the two plates and between the cylinders, this device making it possible to ensure effective lubrication of the friction surfaces between the small faces and the cylinders and a maintenance of the plates of the small faces in a very precise position relative to the cylinders.

For this purpose, the cylinders have on each of their front faces, an annular groove having the axis of the cylinder axis, in an area in contact with one of the plates of a small face, so that the plate and groove cooperate during the rotation of the cylinder, for the maintenance and / or lubrication of the small face.

In order to clearly understand the invention, a description will now be given, by way of nonlimiting example, with reference to the appended figures, a device for continuously casting a metal strip according to the invention.

Figure 1 is a partial sectional view through a horizontal plane along 1-1 of Figure 2 of a continuous casting device according to the invention and according to a first embodiment.

Figure 2 is a sectional and elevational view along 2-2 of Figure 1.

FIG. 3 is a side view of a plate of the continuous casting device along 3 of FIG. 2.

Figure 4 is a partial sectional view through a horizontal plane of a continuous casting device according to the invention and according to an alternative embodiment.

Figure 5 is a partial sectional view along 5-5 of Figure 6 of a continuous casting device according to the invention and according to a second embodiment.

FIG. 6 is a front view of the casting device, along lines 6-6 of FIG. 5.

In Figures 1 and 2, we see a continuous casting device between cylinders which comprises two cylinders 1 and 2 having axes which are parallel to each other and horizontal and which are arranged with a certain spacing corresponding to the thickness of the product to be cast.

In FIG. 1, the device has been represented in section by a horizontal plane passing through the axes of the cylinders 1 and 2.

During casting, cylinders 1 and 2 are rotated in opposite directions and liquid metal is introduced into a casting space 3 delimited by the lateral surfaces of the cylinders arranged opposite and by two lateral walls such as the wall 4, called small faces, which are in abutment on the axial ends of the cylinders 1 and 2.

The casting space 3 has a minimum width corresponding to the spacing of the cylinders 1 and 2 and to the thickness of the cast product, in the horizontal plane containing the axes of the cylinders 1 and 2.

The cylinders 1 and 2 are internally cooled and ensure the solidification of the liquid metal introduced into the casting space 3, so that solidified metal skins are formed in contact with the surface of the cylinders 1 and 2 which entrain the liquid metal solidified in the direction of the narrower part of the casting space 3, or neck, at which the solidified skins meet.

The solidified product is continuously extracted below the cylinders.

The small faces such as the face 4 are intended to seal the casting space 3 on its lateral sides, so as to prevent any infiltration of liquid metal.

The cylinders 1 and 2 comprise a central metallic core of steel 1a (or 2a) and an external ferrule of copper 1b (or 2b) comprising channels, not shown, in which a liquid such as de water, to ensure the cooling of the corresponding ferrule 1b (or 2b) which comes into contact with the liquid metal introduced into the casting space 3.

The small faces such as the face 4 have two plates, preferably metallic, 5 and 6 having the shape of annular sectors, as can be seen in FIG. 2.

The plates 5 and 6 which are fixed and which come into frictional contact with the external peripheral part of the cylinders comprising the cooled ferrules 1b and 2b could also have the shape of disc portions, as described in patent application 90-11000.

The plates 5 and 6 are preferably made of steel but can also be made of other metals or even of non-metallic material. They have an outer edge of frustoconical shape whose largest diameter is equal to the diameter of the cylinders 1 and 2. The edge 7 or 8 of the metal plate 5 or 6 located at the end of the frustoconical edge having the largest diameter is arranged in coincidence with the edge of the corresponding cylinder 1 or 2.

The closing of the casting space 3, between the cylinders 1 and 2, is ensured by two pieces of refractory material 9 and 10 which have frustoconical bearing surfaces whose shape corresponds to the shape of the frustoconical edge of the plates 5 and 6, which are attached to each other along a flat face and which are interposed between the metal plates 5 and 6.

The refractory pieces 9 and 10 are held inside a housing 12 which allows the small face 4 to bear against the corresponding axial ends of the cylinders 1 and 2.

The housing 12 has an external edge directed towards the plates 5 and 6 and separated from these plates by a clearance avoiding any contact between the housing 12 and the plates 5 and 6. There is no direct mechanical connection between the housing 12 and the plates 5 and 6, the small face 4 being kept in contact with the axial ends of the cylinders 1 and 2, by means of helical springs 14 interposed between the interior surface of the housing 12 and pressure plates 15 coming into contact with an external flat surface of the pieces of refractory material 9 and 10.

In addition, helical springs 16 distributed around the housing 12 and interposed between the housing and support parts 17 in contact with the edge of the refractory parts 9 and 10 allow these parts to be held firmly against each other, according to their bearing faces.

By exerting a bearing force on the housing 12, in the axial direction of the cylinders 1 and 2, the bearing of the refractory pieces 9 and 10 is carried out on the metal plates 5 and 6 and the bearing of the metal plates 5 and 6 on the outer end portions of cylinders 1 and 2.

According to the invention, the cylinders 1 and 2 comprise annular grooves 19 and 20 machined inside annular parts 21 and 22 attached to the front faces of the ferrules 1b (or 2b).

The grooves 19 and 20 have as their axis the axis of the corresponding cylinder 1 or 2.

As can be seen in FIGS. 1 and 3, the metal plates 5 and 6 have on their faces directed towards the corresponding cylinder 1 or 2, a rib in the form of an annular sector 23 or 24 whose width is substantially identical to the width of the groove 19 (or 20), so that the annular rib 23 or 24 penetrates inside the corresponding groove, in the service position of the small face, as shown in FIG. 1.

As can be seen in FIG. 3, the annular rib 23 of the metal plate 5 has two end parts 23a and 23b whose shape corresponds substantially to the shape of the section of the corresponding groove 19 and an intermediate part 23c having a height less than the height of parts 23a and 23b. Of in this way, a free space is provided, inside the groove 19, between the parts 23a and 23b, when the metal plate 5 is fixed in position against the front end of the cylinder 1.

This free space delimited by the parts 23a and 23b inside the groove 19 makes it possible to constitute a reserve of grease ensuring the lubrication of the friction surfaces of the metal plate 5 and of the cylinder 1.

In particular, this ensures lubrication of the friction surfaces of the annular rib 23 and of the groove 19.

The rib 24 of the metal plate 6 has a profile identical to the profile of the rib 23 of the plate 5; the plate 6 is lubricated by introducing grease between the end parts of the rib.

As a variant, it is possible, as shown in FIG. 1, to provide guide and holding ribs 23 and 24 of the metal plates 5 and 6 whose height is less than the depth of the corresponding groove 19 or 20.

A free space is thus provided at the bottom of the groove 19 or 20 and this free space can be supplied with a lubricant such as oil through a pipe 25 or 26 passing through the support pieces 17 and the metal plates 5 and 6 to open into the free space at the bottom of the groove 19 or 20.

In this way it is possible to ensure continuous lubrication of the friction surfaces of the plates 5 and 6 and of the cylinders 1 and 2.

The annular ribs 23 and 24 introduced into the grooves 19 and 20 make it possible to ensure extremely efficient positioning, centering and holding in position of the plates 5 and 6, during casting, so that the external edge 7 or 8 of plates 5 or 6 is maintained in perfect alignment with the edge of the corresponding cylinder 1 or 2.

This arrangement also makes it possible to achieve perfect alignment of the sides of the two cylinders 1 and 2 which may have slight dimensional differences due to the precision of the machining and of the adjustment, during assembly.

During the expansion of the cylinders during casting or during a horizontal displacement of these cylinders, the metal plates 5 and 6 of the small face 4 keep their initial positioning relative to the cylinders 1 and 2, so that the small face remains perfectly waterproof.

In the case where the cylinders 1 and 2 move relatively to one another in a direction perpendicular to their axis, this displacement can result, in the case of a spacing of the cylinders, by a slight spacing of the parts 9 and 10 and by infiltration and freezing of the steel between the pieces of refractory material 9 and 10.

The use of two refractory pieces added against each other instead of a single piece thus allows a slight spacing of the cylinders.

On the other hand, in the case of a displacement of the cylinders resulting in their approximation, this displacement can only be accommodated if the material of the refractory piece or pieces interposed between the plates 5 and 6 is capable of accepting a certain compression.

As can be seen in FIG. 2, the ends of the annular sectors constituting the metal plates 5 and 6, in the direction of rotation of the corresponding cylinder 1 or 2, are supported on fixed stops 27 and 28 which make it possible to avoid the drive in rotation of the metal plates 5 and 6 by the cylinders 1 and 2.

The stops 27 and 28 have no role as regards the radial positioning of the metal plates 5 and 6 relative to the cylinders 1 and 2.

In Figure 4, there is shown an alternative embodiment of a small face 4 'of a continuous casting device between cylinders according to the invention, allowing to accommodate a certain displacement of the cylinders 1' and 2 'l' one compared to the other resulting in a bringing together of their axes.

The metal plates 5 ′ and 6 ′ of the small face 4 ′ have, like the plates 5 and 6 of the small face 4 shown in FIG. 1, ribs in the form of portions of rings introduced into grooves machined in the ends fronts of the corresponding cylinders 1 'and 2'.

The metal plates 5 ′ and 6 ′ further comprise two frustoconical faces 5 ′ a and 6 ′ a inclined in the direction of the casting space 3 ′ on which bear corresponding frustoconical faces of two pieces of refractory material 9 ′ and 10 '.

The pieces 9 ′ and 10 ′ of refractory material are held in abutment against the plates 5 ′ and 6 ′ and brought back against each other by springs.

In the case of a relative displacement of the cylinders 1 'and 2' resulting in a bringing together of their axes, the surfaces 5'a and 6'a of the metal plates 5 'and 6' linked to the cylinders during their displacement move by sliding on the tapered faces of the pieces of refractory material 9 'and 10'.

FIGS. 5 and 6 show a second embodiment of a continuous casting device according to the invention making it possible to ensure effective lubrication of the surfaces of the metal plates of the small faces and of the axial ends of the cylinders, during the casting.

The continuous casting device generally designated by the reference 30 shown in Figures 5 and 6 comprises two counter-rotating cylinders 31 and 32 arranged with a certain spacing so as to delimit between them a casting space 33 which is closed at its ends by side walls such as 34.

The wall 34 is formed by two metal plates 35 and 36 in the form of annular sectors having a frustoconical edge which are pressed against the front faces of the cylinders 31 and 32 and by a piece of refractory material 37 interposed between the metal plates 35 and 36.

During casting, the metal plates 35 and 36 are in frictional contact with the external part of the cylinders 31 and 32 which rotate in opposite directions.

According to the invention, the cylinders 31 and 32 have grooves 39 and 40 of annular shape having as axis the axis of the corresponding cylinder 31 or 32.

A lubricant is introduced into the grooves 39 and 40, in the form of a grease filling these grooves or in the form of a liquid stream introduced into the grooves 39 and 40 during casting.

The grooves 39 and 40 are machined in a part of the front faces of the cylinders 31 and 32 which is covered by the metal plates 35 and 36. The faces of the metal plates 35 and 36 coming into contact with the front faces of the cylinders 31 and 32 cooperate with the groove 39, during the rotation of the cylinders 31 and 32, to ensure distribution and distribution of lubricant between the metal plate and the cylinder.

In the case of the use of a low viscosity lubricant, for example a liquid lubricant, it may be necessary to have fixed closure plates 41 and 42 in contact with the front faces of the cylinders 31 and 32, in the parts of these front faces which are not covered by the metal plates 35 and 36. One thus realizes a complete closure of the grooves 39 and 40 ensuring the distribution of lubricant between the friction surfaces of the cylinders 31 and 32 and of the plates 35 and 36 supported on these faces frontal.

The plates 41 and 42 can be constituted by discs or by rings covering the grooves 39 and 40.

In the case of the second embodiment shown in FIGS. 5 and 6, the grooves 39 and 40 do not have the function of ensuring the positioning and the maintenance of the metal plates 35 and 36 of the small faces, by cooperation of a annular rib and grooves 39 and 40.

The device according to the invention although of a simple structure makes it possible to appreciably improve the conditions of the casting.

In particular, the wear of the friction parts can be considerably reduced.

The invention is not limited to the embodiments which have been described.

One can imagine devices comprising metal plates bearing on the front faces of the cylinders of a shape different from those which have been described between which one or more complementary pieces of refractory material are attached.

One can imagine other arrangements of the small faces making it possible to accommodate a relative displacement of the cylinders by spacing or by approximation.

The invention applies not only to the continuous casting between cylinders of thin metal strips but also to the continuous casting between cylinders of any metallic product.

Claims (10)

1.- Device for continuous casting of a metallic product comprising two cylinders (1, 2; 1 ', 2'; 31, 32) contra-rotating with parallel axes arranged opposite each other with a certain spacing and two fixed side walls (4, 4 ', 34) or small faces, bearing on the axial ends of the cylinders (1, 2; 1', 2 '; 31, 32) delimiting a casting space (3, 3', 33) between the cylinders and each comprising two plates (5, 6; 5 ', 6'; 35, 36) which are in rubbing contact each with a flat front face of one of the two cylinders at one of the axial ends of the cylinders and at minus a complementary wall (9, 10; 9 ', 10'; 37) interposed between the two plates (5, 6; 5 ', 6'; 35, 36) and between the cylinders (1, 2; 1 ', 2 '; 31, 32) characterized in that the cylinders (1, 2; 1', 2 '; 31, 32) have on each of their front faces, an annular groove (19, 20, 39, 40) having for axis the axis of the cylinder, in an area in contact with one of the p lacquers (5, 6; 5 ', 6'; 35, 36) of a small face, so that the plate (5, 6; 5 ', 6'; 35, 36) and the groove (19, 20, 39, 40) cooperate during the rotation of the cylinder, to maintaining and / or lubricating the small face (4, 4 ', 34). 2.- Device according to claim 1, characterized in that each of the plates (5, 6) has a rib in the form of an annular sector (23, 24) engaged inside the groove (19, 20) of the cylinder corresponding to ensure the maintenance of the plate (5, 6) in a radial arrangement fixed relative to the corresponding cylinders (1, 2). 3.- Device according to claim 2, characterized in that the plates (5, 6) have a circular edge (7, 8) whose diameter is identical to the diameter of the corresponding cylinder (1, 2) kept in coincidence with the edge of the corresponding cylinder (1, 2), by the annular rib (23, 24) introduced into the groove (19, 20) of the cylinder (1, 2). 4.- Device according to any one of claims 2 and 3, characterized in that the annular rib (23) has two end parts (23a, 23b) whose shape and dimensions correspond to those of the groove ( 19) and a central part (23c) providing a free space inside the groove (19), this free space being filled with a lubricant during casting. 5.- Device according to any one of claims 2 and 3, characterized in that the annular rib (23) provides a free space in the bottom of the groove (19), in communication with a lubricant supply means (25) through a through opening of the plate (5). 6.- Device according to any one of claims 1 to 5, characterized in that it comprises two complementary parts (9, 10) of refractory material interposed between the two plates (5, 6) of a small face ( 4), reported against each other. 7.- Device according to any one of claims 1 to 6, characterized in that each of the small faces (4) comprises a housing (12) having no direct mechanical connection with the plates (5, 6) of the small face (4) inside which are placed the complementary part (s) (9, 10) of the small face (4), the inner wall of the housing (12) coming to bear on the complementary part (s) (9, 10) by means of elastic return means (14), so as to exert a bearing force in the axial direction of the cylinders on the complementary part or parts (9, 10) and by their intermediary on the plates (5 , 6). 8.- Device according to claim 6, characterized in that elastic means of reminder (16) are interposed between the inner wall of the housing (12) and each of the two complementary parts (9 and 10) to ensure the abutment against one another of these complementary parts (9, 10). 9.- Device according to claim 6, characterized in that the plates (5 ', 6') have frustoconical surfaces (5'a, 6'a) inclined in the direction of the casting space (3 ') and that the two complementary parts (9 ', 10') have corresponding surfaces capable of moving by sliding on the surfaces (5'a, 6'a) of the plates (5 ', 6'), during a movement by bringing cylinders (1 ', 2') in a direction perpendicular to their axis. 10.- Device according to claim 1, characterized in that the grooves (39, 40) of the cylinders (31, 32) are connected to a lubricant supply means and that the device further comprises fixed plates (41 , 42) for closing the grooves (39, 40) bearing on the front faces of the cylinders (31, 32), outside the zones on which the plates of the side walls (35, 36) come to bear.

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