FR2670143A1 - DEVICE FOR CONTINUOUS CASTING A THIN STRIP OF METAL, IN PARTICULAR STEEL. - Google Patents

Abstract

The device according to the present invention comprises two cooled parallel cylinders (1, 2), arranged facing one another so as to define between them a casting space (3) for the liquid metal (4), said cylinders (1, 2) being, during casting, rotated in the opposite direction, and two lateral closure walls (12) of said casting space (3) placed at the ends of the rolls. The cylinders (1, 2) have at each of their ends a concentric disc (10, 11) of the same diameter and driven in rotation at a speed greater than that of said cylinders (1, 2).

Description

The present invention relates to a device

  continuous casting between moving walls, in particular

  bind for casting between rolls of a thin strip

of metal, especially steel.

  Installations of this type are known which comprise two parallel cylinders that are vigorously cooled, arranged facing one another so as to define between them a casting space for the liquid metal, determining the thickness of the product.

* jg sunk -

  The casting space is closed towards the ends of the rolls by closing walls

  lateral, commonly called "small faces".

  As is known, the cast metal tends to solidify in contact with the side walls which are generally fixed, which leads to the formation of a

corner of solidified metal.

  This solidified metal wedge can pass between the rolls only when it is rolled at the risk of blocking the rolls or else leading to

  pierced on the edges of the cast strip.

  Various means have been proposed up to now to prevent this undesirable solidification of the liquid metal on the small faces, in particular the use of magnetic inductors arranged near these

  and intended for heating the liquid metal.

  However the proposed solutions in this sense

  are relatively complex and have not

  faction. Another proposed solution consists in producing the two-part closing side walls, a fixed, insulating or heated upper part and a lower part, at the plane of the cylinder axes, consisting of a strip or block chain driven to the same speed as the cast tape, and which holds the edge of said tape

while accompanying him.

  But, this solution is not enough because it can still happen an excess of

  solidification on the edges of the rolls.

  The object of the present invention is to provide a device for continuous casting of thin strips of metal which does not have the disadvantages

* O of the aforementioned devices.

  The subject of the present invention is a device for continuous casting of a thin strip of metal, in particular of steel, comprising two cooled parallel rolls arranged facing each other so as to define between them a casting space. for the liquid metal, said rolls being rotated in rotation in opposite directions during rotation, and two lateral sealing walls of said casting space at the ends of the rolls, characterized in that the rolls comprise at each of their ends a disc concentric, of the same diameter and rotated at a speed

  greater than that of said cylinders.

  According to other characteristics: 2 to 5 the discs are cylindrical or frustoconical, the peripheral surface of the discs in contact with the liquid metal is knurled or has a controlled roughness, n o the excess speed of rotation of the discs is less than 10% of the speed of rotation of the rolls, the discs are rotated by friction by at least one motor, the discs are rotated by gears driven by at least one motor, the contact surfaces between the discs

  and the corresponding cylinders are lubricated.

  The invention will be better understood by means of

  the description which will follow, given only to

  By way of example, and with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic perspective view of one end of the rolls of the continuous casting apparatus according to the invention, FIG. plan view of one end of the rolls of the casting device, Figs 3 and 4 are diagrams showing the solidification profiles of the metal strip, Fig 5 is a top view of one end of the rolls according to a second embodiment of the device according to the invention, FIG. 6 is a view from above of one end of the rolls according to a third form of

  embodiment of the device according to the invention.

  Figs 7 and 8 are two views respectively of

  side and front end of the casting device

  equipped with two-part lateral closing walls.

  The device represented in FIGS. 1 and 2 is intended for the continuous casting of thin strips of metal, in particular of steel, between two parallel cylinders 1 and 2 arranged facing one another so as to determine between them a space casting 3

for a bath of liquid metal 4.

  These cylinders 1 and 2 are during rotation driven in rotation in opposite directions at a speed VO, according to the arrows indicated in FIG.

  motor 5 and transmission means which are not

  your. The 4-molten metal is poured into the space 3 located between the cylinders 1 and 2 above the plane passing through the axes of said cylinders, that is to say above the "neck" 6 between the cylinders. The cylinders 1 and 2 are cooled and the molten metal solidifies on contact so that the product 4 has at least solidified on the surface, can be extracted down below the cylinders during

1 o of their rotation.

  According to the invention, the cylinders 1 and 2 comprise at each of their ends, a disc 10 and 11 concentric, of the same diameter and driven in rotation in opposite directions, at a speed

  * 5 V 1, according to the arrows shown in Fig 1.

  To contain laterally the metal, the device comprises a side closure wall 12 or "small face" disposed on each side of the space of

casting 3.

  The closure wall 12 is preferably

made of insulating material.

  The disks 10 and 11 are mounted free in

  rotation on the shaft la and 2 has respective cylinders

  1 and 2 and are rotated so that the tangential velocity V 1 of said disks is greater than the tangential velocity V O of said cylinders. The excess speed of rotation of disks 10 and 11 is less than 10% of the speed of

3 o rotation of cylinders 1 and 2.

  The disks 10 and 11 are rotated, for example by friction, as shown in FIG. 2, either by a motor 13 or by a single motor and transmission means (not shown). The training of discs 10 and 11 can

  also be realized by gears.

  According to a first embodiment * shown in Figs 1 and 2, the disks 10 and 11 are cylindrical. As is known, the liquid metal 4 cast tends to solidify in contact with the walls

lateral shutter 12.

  The purpose of the present invention is to create

  thanks to the disks 10 and 11, two solidification regimes

  in the casting space 3 between the large faces constituted by the cylinders 1 and 2 and the banks formed by the lateral sealing plates 12 by bringing an excess of heat to the edges

  cast metal by different flow rates of metal.

  Indeed, as shown in FIGS. 3 and 4, the solidification zone A of the liquid metal 4 between the rolls 1 and 2 is located substantially at the neck 6 while the solidification zone B of said liquid metal between the discs 10 and 11 is located downstream of solidification zone A and by

  the result of pass 6, thanks to the speed

  gential V 1 of disks 10 and Il which is greater than

  the tangential velocity VO of cylinders 1 and 2.

  The banks of the strip thus have a contact time with discs 10 and 11 lower than the central zones of the strip in contact with the rolls 1

  and 2 so that their solidification is delayed.

  This allows evacuation of the area of the small face still not completely solidified which avoids the

  formation of a "corner" of solidified metal.

  In two other embodiments of the invention illustrated in FIGS. 5 and 6, the discs and 11 may be frustoconical with a slope directed either towards the center of the cylinders 1 and 2 (FIG. 5), or towards the outside of said cylinders.

(Fig 6).

  The device according to the present invention can be applied whatever the principle of the

  "small faces" for closing the casting space 3.

  Indeed, the small faces may be constituted by shutter plates 12 in one piece, fixed, as shown in Figs 1 and 2, or by shutter plates 20 in two * 10 parts, an upper portion 20 a fixed, insulating or heated and a lower portion 20b, at the neck 6 of the cylinders 1 and 2, constituted by a strip or a block chain driven by a motor 21 at a linear speed V 2 equal to the tangential speed

  V 1 disks 10 and 11 (Figs 7 and 8).

  Furthermore, the peripheral surface of the disks 10 and 11 may be knurled or have a controlled roughness to promote the entrainment of the sodified metal and the contact surfaces between the disks 10 and 11 and the cylinder 1 and 2 corresponding

can be lubricated.

  The continuous casting device according to the present invention makes it possible to avoid the formation of a solidified metal wedge and makes it possible to stress the edge of the metal strip so that, at low overspray of the discs, elongation of the edges occurs. the band with respect to the center which favors its centering on the downstream line or, at higher speed, there is a breakthrough

  volunteer at the banks of the Strip.

Claims (8)

  1 Device for continuous casting of a thin strip of metal, in particular of steel, comprising two cooled parallel cylinders (1, 2) arranged facing one another so as to define between them a casting space ( 3) for the liquid metal (4), said rolls being cast in the opposite direction, and two closing walls (12, 20) of said casting space (3) at the ends of the rolls (1, 2), characterized in that the cylinders (1, 2) have, at each of their ends, a concentric disc (10, 11) of the same diameter and rotated at a speed   greater than those of said cylinders (1, 2).   2 Device according to claim 1, characterized in that the discs (10, 11) are cylindrical. 3 Device according to claim 1, characterized in that the discs (10, 11) are truncated.   4 Device according to one of the claims   1 to 3, characterized in that the peripheral surface of the discs (10, 11) in contact with the liquid metal   (4) is knurled, or has a controlled roughness.   5 Device according to any one of   preceding claims, characterized in that   the excess speed of rotation of the disk (10, 11) is less than 10% of the rotational speed of the cylinders (1, 2).   6 Device according to any one of   preceding claims, characterized in that the   discs (10, 11) are rotated by   friction by at least one motor (13).   7 Device according to any one of   Claims 1 to 5, characterized in that the   disks (10, 11) are rotated by   Claims 1 to 5, characterized in that the   disks (10, 11) are rotated by   gears driven by at least one motor.   8 Device according to claim 1, characterized in that the contact surfaces between the discs (10, 11) and the cylinder (1, 2) are lubricated.