AU695332B2

AU695332B2 - Side wall for a continuous sheet metal casting machine

Info

Publication number: AU695332B2
Application number: AU28901/95A
Authority: AU
Inventors: Jacques Barbe; Frederic Caillaud; Pierre Delassus; Philippe Guillo; Luc Vendeville
Original assignee: Vesuvius France SA
Current assignee: Vesuvius France SA
Priority date: 1994-06-30
Filing date: 1995-06-23
Publication date: 1998-08-13
Anticipated expiration: 2015-06-23
Also published as: DE69502607D1; NO313581B1; ATE166266T1; MX9700088A; CA2193243A1; SK168096A3; HUT76203A; PL178918B1; CZ383896A3; CN1155857A; HU9603603D0; BR9508141A; EP0767714B1; ES2118606T3; PL318137A1; DE69502607T2; CA2193243C; NO965622D0; CN1071605C; EP0767714A1

Abstract

A side wall for a continuous casting machine for sheet metal consisting of a frame with two counter-rotating rollers (2) mounted thereon, two side walls (10) arranged at each end of the rollers (2), and a device for pressing the side walls against the roller ends. The rollers and the side walls together define a continuous casting mould containing an amount of liquid metal. The side wall includes a plate (12) made of a non-metal refractory material for engaging the roller ends, and a metal portion (14) for attaching the side wall to the frame of the continuous casting machine. Said metal portion consists of a rim enclosing only the edges of the plate (12) of refractory material.

Description

1 LATERAL FACE FOR A SHEET CONTINUOUS CASTING MACHINE This invention relates to a lateral face for a sheet continuous casting machine formed of a frame on which two mobile walls are mounted, such as two cylinders rotating in opposite directions, and two lateral faces placed at each of the ends of the cylinders so as to delimit a continuous casting mould retaining a given quantity of a liquid metal.

The conventional continuous casting of a thin slab in a mould with fixed walls does not make it possible to obtain a thickness of less than about 50 mm. When it is desired to obtain thinner products, it is necessary to roll the slabs which come out of the casting mould.

This is why for several years an attempt has been made to develop sheet continuous casting methods so as to directly obtain products whose thickness can be 3 mm or less. Thus, it is possible to dispense with the obligatory hot rolling operation by the methods currently used. This results in simplifying production and reducing the amount of energy required, thus reducing the cost price of the finished product.

A sheet continuous casting machine generally comprises two mobile walls facing each other and which delimit a mould with mobile walls. The liquid steel derived from the distributor is introduced into this mould by means of a nozzle with an appropriate Sgeometry.

There already exists a sheet continuous casting machine of this type (EP 0 546 206). This machine is formed of two rollers with parallel and horizontal axes rotating in an opposite direction. Two lateral faces are disposed at each of the ends of these two rollers so as to determine the continuous casting machine into SP 13012 MdT i 2 which the liquid steel is introduced from the distributor. The lateral faces are applied by a mechanical system, possibly constituted by springs or jacks, against the end of the cylinders so as to embody sealing to the liquid steel. The lateral faces can be preheated before casting depending on the operating mode of the machine and the materials constituting said faces. According to this document, the lateral faces are formed of a ground plate made of a refractory material, and an element made of a ceramic material which is in contact with the friction surface of the end of the cylinders and which is embedded in the ground plate. All these elements are mounted in a metallic casing which covers the rear face of the ground plate leaving free solely the ceramic element.

The bottom of this casing ensures transmission of the pressure exerted by the mechanical system located at the rear of the lateral face and which enables the lateral face to be sealed against the cylinders so as to prevent any liquid steel leak occurring between said cylinders and the lateral walls.

However, in a lateral face of this type, the presence of the metallic bottom of the casing poses several problems.

During this continuous casting, the heat flow coming from the liquid metal through the refractory plate provokes a significant increase of the temperature of the bottom of the casing. If no casing cooling device is provided, this temperature increase provokes a warping of the bottom, such as a swelling.

Apart from other factors, this warping is responsible for an incorrect transmission of the pressure exerted by the mechanical system on the rear of the refractory plate. Because the bottom is warped, the pressure is not uniformly applied to the refractory plate but is concentrated on certain points of the latter. For SP 13012 MdT 3 example, if the plate is swollen, the bottom of the metallic casing shall only be applied to the refractory plate by the top of this swollen area. The resultant stress concentration may result in breaking the refractory plate. The warping of the casing can 0

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0 s e S 30 q- \0 V T i- r;l-o*Y l ~1--111- jl- -il ^X _;lii~_(lii i:iii- t(t t pI C C 44ff ft also cause a modification of the parallelism of the front face of the lateral face (refractory material) with its rear face (metallic bottom). On account of this parallelism modification, the friction surface is no longer applied uniformly, that is with a constant pressure, on the end of the cylinders. This phenomenon may result in an infiltration of liquid steel between the cylinder and the friction surface of the lateral face.

The installation of a system for cooling the metallic casing and particularly the bottom of this casing is able to limit the disadvantages described 15 above, but provokes a cooling of the surface of the refractory material of the lateral face which is in contact with the liquid steel. This increases the risk of the steel solidifying on this surface and can impede the proper course of casting.

In addition, when producing the lateral face, it is difficult to obtain good parallelism between the front face (refractory material) and the rear face (metallic bottom). In fact, the ground plate made of the refractory material is cemented inside the metallic 25 casing so as to keep it in place. The cement is baked according to a heat cycle able to reach and exceed 200°C. This baking cycle causes a warping of the metallic casing which destroys the parallelism which existed prior to baking of the cement. It is not easy to re-establish parallelism between the front face and the rear face by means of a new grinding because it is necessary to lubricate during grinding, which dampens the cement which thus needs to be baked again.

The Jacanese abstract, vol 12 no 229 (M-714) 29 June 1938 describes a lateral face formed .4 *e t l r cr f f ft I 4 ft i i i i tE 4 of two half-plates guided into an open stirrup forming a bottom.

The French patent 2 693 135 describes a lateral face comprising a fibrous refractory plate mounted in a metallic casing provided with a bottom.

Accordingly, the present invention relates to a lateral face for a sheet continuous casting machine and at least some embodiments may resolve or ameliorate the disadvantages of the prior art mentioned above. This lateral face may make it possible to transmit and equally distribute the application pressure exerted on its rear face so as to avoid leakage of the liquid steel.

The lateral face may also provide good parallelism between its front face and rear face.

A first aspect of the invention, is characterised in that a metallic portion able to secure the lateral face to the frame of the continuous casting machine is formed of a belt surrounding the refractory plate solely on its periphery.

This solution allows for good geometrical support of the refractory 20 plate, easy fixing of the lateral face to the frame of the continuous casting machine and good parallelism between the two faces of the lateral wall irrespective of the temperature. This solution also makes it possible to embody a lateral face made totally of a refractory material at the level of all the areas in contact with the liquid steel or the cylinders, as well as with the pressure application device.

The assembling of the metallic belt and the refractory plate can be :r carried out by cementing or hot hooping. If assembling is carried out by .means of cementing, the metallic belt and/or the refractory plate preferably has grooves or bracings which can be filled with cement so as to ensure 30 improved retaining of the refractory plate in the belt.

~The refractory plate is cemented per zone inside the metallic belt. The S" fixing cement also cannot be kL i I W- W W-~

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disposed on the entire circumference of the refractory element according to the shape of the metallic belt.

For example, when the internal shapes of the belt and refractory plate are constituted by two arcs of a circle concentric to the cylinder, the expansion differences between the belt and the refractory plate require that the entire circumference of the plate is not cemented so as to prevent the latter from cracking.

In fact, in this configuration, the presence of cement on both sides of the level of the axis of the cylinders provokes at high temperatures a clamping of the refractory plate at this level. The belt is made of metal (steel, cast iron, etc.) whose heat expansion coefficient is higher than that of the refractory material constituting the plate. Thus, at high temperatures, the metal expands more. The belt then provokes the pulling of the refractory plate until the latter is possibly broken.

The cement used may be silico-high alumina cement with a silicate binder and its purpose is to Ipermanently or temporarily keep the refractory plate in the belt.

The surface evenness of the rear face of the refractory material is preferably at least 0.5 mm. In other words, the surface of the rear face needs to be fully contained between two parallel planes separated by 0.5 mm at the most.

The refractory plate can be formed of a single element. It can also be composed of several portions, in particular a friction zone and a central zone solely in contact with the liquid steel contained in the continuous casting mould.

The central zone is preferably made of a ceramic material with a carbon binder.

According to one advantageous characteristic, at least one portion of the friction zone is located below SP 13012 MdT 4I 6 the plane defined by the spin axes of each of the two cylinders.

A second aspect of the invention relates to the lateral faces for a sheet contiaiuous casting machine formed of a frame on which two cylinders rotating in an opposite direction are mounted, as well as two dismantable lateral faces placed at each of the ends of the two cylinders and means to apply with a contact pressure the lateral faces to the ends of the cylinders, It is characterised in that the means to apply a contact pressure of the lateral faces to the ends of the cylinders include a plate applied to the rear face of the refractory plate without any contact with the metallic belt of this refractory plate, the thickness of the plate being more than the thickness of the belt, By means of this characteristic, the pressure exerted on the lateral face and intended to provide sealing between the cylinders and the friction surface of this lateral face is exerted by means of an element, possibly metallic, and independent of the lateral face itself. This plate is of course 20 subjected to the flow of heat which traverses the refractory plate, As a result, 4. its temperature 'rises during functioning of the continuous casting machine.

However, the rise of temperature of the metallic plate is limited by the fact 4: that an independent non-conductor (such as a silica foam plate) can be 4• introduced between the thrust plate and the actual lateral face and that there is no thermal bridge between the metallic belt supporting the refractory plate and the thrust plate which applies pressure to the rear face of the refractory plate. In fact, as mentioned earlier, the thickness of the metallic belt is smaller than that of the refractory plate so that the surface of the belt stands back with respect to the surface of the refractory plate. In addition, the 30 invention concerns a continuous casting V t

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L I I 7 device between cylinders of thin metallic products comprising two cooled counter-rotating cylinders, two lateral sealing walls and means for supporting and applying pressure of said sealing walls against the narrow edges of the cylinders, characterized in that each sealing wall is constituted by a hard refractory plate surrounded by a metallic plate to which it is linked.

Other characteristics and advantages of the present invention shall appear more readily from a reading of the following illustrative description of embodiment examples. On these drawings figure 1 is a perspective diagrammatic view of a sheet casting machine between cylinders figure 2 ,s a perspective view of a first embodiment of the irvention figure 3 is a sectional view of details of the plate of figure 2 figures 4 and 5 show two other embodiment variants figure 6 is a sectional view figure 7 is a sectional view of another embodimentc variant.

Figure 1 shows a perspective diagrammatic view of a sheet casting machine. It comprises two cylinders 2 rotating in opposite directions, as illustrated by the .arrows 4 around horizontal axes 6. Plates 10 applied r against the ends of the cylinders constitute a mould into which the liquid steel is poured.

Figure 2 shows a first embodiment of a lateral wall for a sheet continuous casting machine conforming to the invention. This lateral wall denoted by the general reference 10 is formed of two portions, namely a refractory plate 12 and a metallic belt 14. This figure shows that the refractory plate has a shape adapted to that of the cylinders of the continuous SP 13012 MdT i 8 casting machine. It comprises two large sides with approximately the shape of an arc of a circle whose centre of curvature is located on the central axis of the cylinders of the casting machine. The plate 12 has one small side at its lower portion and a large side at its upper portion.

The plate 12 is kept in place by a metallic belt 14 whirh in the example represented surrounds the plate 12 over its entire circumference, the belt being able to be mounted by hooping. The metallic belt 14 comprises fixing devices, such as screws, bolts, stud bolts or other similar devices able to secure it to the i frame of the continuous casting machine. Given the fact that these fixing devices are conventional, they are not shown on the figure.

As the figure shows, the thickness of the 4 refractory plate 12 is larger than that of the metallic Sbelt 14. Thus, the refractory material goes past the two sides of the belt. According to the invention, a lateral face is embodied in which the metallic belt stands back by 3mm with respect to each of the front and rear faces of the refractory material 12. In other words, the thickness of the refractory plate was 6 mm v larger than that of the metallic belt 14.

As can be seen on figure 3, which represents a.

cross section of the metallic belt 14 and of one portion of the refractory plate 12, the metallic belt 14 comprises a groove 14a, whereas the refractory plate comprises a groove 12a. The grooves 12a and 14a are filled with cement 16 which keeps the plate 12 in the belt 14.

A thrust plate 15 transmits an application force transmitted by application means 17. It is to be noted that the thickness of the plate 12 is larger than that of the metallic belt 14. Thus, there is no thermal SP 13012 MdT L i I 1 i li 9 bridge between the thrust plate 15 and the belt or between the belt and the narrow edge of the cylinder 2.

In the embodiment example shown on Figure 2, the refractory plate 12 is formed of a single element. Figure 4 shows a plate 12 formed of two portions, namely a zone 18 comprising the portion of the plate working on friction 11 and a central zone respectively. The friction zone 18 is made of a refractory material which possesses good friction characteristics with a metal, has significant hardness and a good coefficient of friction, such as a material comprising at least 1% boron nitride. The central zone is constituted by the zone of the refractory plate which is in contact with the liquid metal. For this reason, it needs to be extremely resistant to being corroded by the steel. For example, it may be constituted by a ceramic material with a carbon binder.

In the embodiment example shown on Figure 4, the friction zone 18 is c ,,formed of a single element. This element has the general shape of a Y. It 20 comprises the friction zone 18 constituted by a crown arc concentric to one i~%f roller and a crown arc concentric to the other roller. These two branches of 0 f the Y meet at their lower portion so as to form a central zone. As can also be seen on Figure 4, one portion of the friction zone is located below the level of the axis 22 of the two cylinders of the continuous casting machine symbolised by a mixed line (see Fig. The end of the friction zone located below the axis of the cylinders ends in the sheet steel solidification zone by a shift 24 of at least 2 mm, possibly a chamfer or rounded element, so that the sheet steel after being solidified does not rub on a refractory heel 26 located below the shift.

30 The edges of the friction zone 18 located on the side of each of the two cylinders comprises a chamfer 28 or rounded element measuring at least 2mm by 2mm so as to limit the level of the mechanical stresses at the level of said edges. If there is no chamfer, there is in fact a systematic peeling of the edges able to subsequently generate infiltration of the liquid metal.

Given the fact that sealing is required between the friction zone 18 and the cylinders, an evenness of the plane constituted by the entire friction zone 10 of at least 0.5 mm is essential. This requires there be a parallelism between the plane of the friction zone 18 and the rear of the refractory plate 12 of at least 4 mm. However, according to the continuous casting machine and the device for fixing the metallic belt 14 to the frame of this machine, the plane of the friction surface 18 moreover may need to be parallel to the plane of the pressure application device. Similarly, for the same reasons for transmitting the application force of the pressure to the refractory plate 12, the evennness of the rear face of the latter needs to be at least 0.5 mm.

Figures 5 and 6 show an embodiment variant of a lateral face for a continuous casting machine conforming to the invention. In this embodiment, the friction zone is formed of four crown arc-shaped elements 30 concentric to the cylinders and a block 32 contiguous with the crown sections 30. Like the friction zone 18 of figure 3, the block 32 comprises a portion located below the level 22 of the axis of the cylinders.

P It is to be noted also that the crown arcs 30 and the central zone 20 are kept in place in the metallic belt 14 by three cemented zones 34. In fact, the differences of expansion between the metallic belt 14 and the refractory materials constituting the central zone 20 and the elements 30 and 32 respectively require that the entire circumference of the plate 12 be cemented so as to prevent the latter from cracking. The SP 13012 MdT ii t machine, characterized in that said metallic portion is formed of a belt surrounding the refractory plate (12) solely on its periphery.

17. Lateral face for a sheet continuous casting machine constituted by a frame on which two cylinders rotating in opposite directions are mounted and two .r l -rl I4 r i I" rest of the circumference of the plate is lined with fibres 36, for example.

Finally, figure 7 shows an embodiment variant in which the refractory plate 12 includes an independent rear plate 38 formed of a non-metallic refractory material. This plate 38 is used as support for the other elements described previously, namely the crown arcs 30, the central block 32 and the central zone All these elements can be simply placed on the rear plate 38 or even secured to said plate with silico-high alumina cement or a similar substance, for example.

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I 6 SP 13012 MdT L t I I~

Claims

1. Lateral face for a sheet continuous casting machine formed of a frame on which two cylinders (2) are mounted rotating in opposite directions, two lateral faces (10) placed at each of the ends of the cylinders and means to apply with contact pressure the lateral faces to the ends of the cylinders, the cylinders co-operating with the lateral faces so as to delimit a continuous casting mould retaining a given quantity of liquid metal, said lateral face including a plate (12) made of a non-metallic refractory material in contact with the ends of the two cylinders, a metallic portion (14) which makes it possible to fix the lateral face to the frame of the continuous casting machine, characterized in that said metallic portion is formed of a belt surrounding the refractory plate (12) solely on its periphery.

2. Lateral face according to claim 1, characterized in that the belt (14) and/or the refractory plate (12) has grooves or bracings (12a, 14a) which can be filled with the cement (16) so as to ensure that the refractory plate (12) is kept more securely in the belt (14)

3. Lateral face according to claim 1 or 2, characterized in that the refractory plate (12) is cemented by zones (34) in the metallic belt (14)

4. Lateral face according to any one of claims 1 to 3, characterized in that the evenness of the rear face of the refractory plate (12) is at least 0.5 mm. Lateral face according to any one of claims 1 to 4, characterized in that the refractory plate (12) comprises a friction zone (18) and a central zone located in contact with the liquid metal contained in the continuous casting mould. SP 13012 MdT AZ; I de m6tal liquide. La face lat6rale comprend une plaque (12) de mat6riau rdfractaire non m6tallique qui vient en contact avec les extrdmit6s des deux cylindres, une partie mdtallique (14) qui permet de fixer la face lat6rale au bAti de la machine de coulde en continu.

La partie m6tallique est constitu6e d'une ceinture qui entoure la plaque de matdriau refractaire (12) uniquement sur sa pripherie. rr 13

6. Lateral face according to claim characterized in that the central zone (20) is made of a ceramic material with a carbon binder.

7. Lateral face according to claim 5 or 6, characterized in that one portion of the friction zone (18) is located below the plane defined by the spin axes of each of the two cylinders.

8. Lateral face according to claim 7, characterized in that the portion of the friction zone (18) located below the plane defined by the spin axes of each of the two cylinders is ended by a shift with respect to the friction plane by a depth of at least 2 mm, this shift being constituted by a chamfer or a rounded element.

9. Lateral face according to any one of claims to 8, characterized in that the friction zone (18) is constituted, at least partially, by elements forming crown arcs concentric to the cylinders.

Lateral face according to any one of claims 7 to 9, characterized in that the parallelism between the plane of the surface of the portion working on friction of the friction zone (18) and the rear face of the refractory plate is at least 0.5 mm.

11. Lateral face according to any one of claims to 10, characterized in that the evenness of the friction zone (18) is at least 0.5 mm.

12. Lateral face according to any one of claims 1 to 11, characterized in that the plane of the upper surface of the metallic belt stands back by at least 3 i" 30 mm with respect to the plane of the friction surface.

13. Lateral face according to any one of claims to 12, characterized in that the edge of the friction zone (18) located opposite the end of the cylinders ends by a clearance with a depth of at least 2 mm, this clearance possibly being a chamfer or a rounded element. SP 13012 MdT ~£WO lateral faces are disposed at each of the ends of these two rollers so as to determine the continuous casting machine into SP 13012 MdT VA 130 AMENDED SHEETS OF THE INTERNATIONAL PRELIMINARY EXAMINATION REPORT 12. Lateral face according to any one of claims 1 to 11, characterized in that the plane of the upper surface of the metallic belt stands back by at least 3 mm with respect to the plane of the friction surface. 13. Lateral face according to any one of claims to 12, characterized in that the edge of the friction zone (18) located opposite the end of the cylinders ends by a clearance with a depth of at least 2 mm, this clearance possibly being a chamfer or a rounded element.

14. Lateral face according to any one of claims to 13, characterized in that the friction zone (18) is made of a material including at least 15% boron nitride (BN)

15. Lateral face according to any one of claims to 14, characterized in that the friction zone is composed of several contiguous elements.

16. Lateral face according to any one of claims 1 to 15, characterized in that the refractory plate includes an independent rear plate (38) made of a non- metallic refractory material used as a support for the other elements constituting the plate.

17. Lateral face for a sheet continuous casting machine constituted by a frame on which two cylinders rotating in opposite directions are mounted and two dismantable lateral faces (10) placed at each of the ends of the two cylinders and means (17) to apply with a contact pressure the lateral faces (10) to the ends of the cylinders the two cylinders co- operating with the lateral faces so as to delimit a continuous casting mould retaining a given quantity of liquid metal, characterized in that the means (17) to .appl-y a contact pressure of the lateral faces to the ends of the cylinders include a plate (15) which is SP 13012 MdT I 14 applied to the rear face of the refractory plate (12) without any contact with the metallic plate of this refractory plate the thickness of the plate (12) being greater than the thickness of the belt (14).

18. Continuous casting device between cylinders with thin metallic products comprising two cooled counter-rotating cylinders two lateral sealing walls and pressure application and support means for said sealing walls against the narrow edges of the cylinders, characterised in that each wall is constituted by a hard refractory plate (12) surrounded by a metallic belt (14) to which it is linked.

19. Lateral face as claimed in either claim 1 or claim 17 substantially as hereinbefore described and with reference to the accompanying drawings. Continuous casting device as claimed in claim 18 substantially as hereinbefore described and with reference to the accompanying drawings. O t Dated this Twenty fifth day of May 1998 E VESUVIUS FRANCE SA S'Patent Attorneys for the Applicant: B RICE CO t4 0 i *i c