GB2177956A - Mould for the continuous casting of metal - Google Patents

Abstract

The mould comprises a backing frame (3) and an assembly of individual mould wall plates defining the casting cavity. A mould wall plate (7) comprises two complementary parts (8, 9) one of which (8) affords a surface (11) of the casting cavity (F) whilst the other (9) is shaped to mate with the frame (3). The parts (8,9) mate along an interface (10) at which coolant-conducting passages (13) are provided. Seals (16) may be provided at the interface (10) or a copper foil may be provided between the two parts (8, 9), especially if these are of different materials e.g. copper and steel. <IMAGE>

Description

SPECIFICATION Mould for the continuous casting of metal This invention relates to a mould for the continuous casting of steel or other metal, comprising cooled metal mould plates which are held and braced in a frame, and which, when braced, define the mould cavity.

Continuous-casting moulds of this type for use in vertical and bow-type installations for casting cogs and slabs have been used successfully for a long time (cf. inter alia German Offenlegungsschrift 1,508,902, German Auslegeschrift 1,939,777). The mould plates often have longitudinal cooling slits on their plane side facing away from the mould cavity, but they can also be provided with cooling bores passing through the mould plate in the direction of the continuous strand which is being cast. In slab casting installations particularly, mould plates with cooling slits or water chambers on the rear side are preferred because of the better cooling conditions.

However, there are now also commerically produced continuous-casting moulds of which both the side facing the mould cavity and the side facing the frame are curved to obtain the desired circular arc shape of the cast strand. It is difficult to carry out intensive cooling, for example by means of cooling slits formed on the outer surface, because the surface is also curved int his region, and consequently such plates are also cooled by means of likewise curved cooling bores, within the plates, which extend in the direction of the cast strand and through which the cooling water flows.Apart from the fact that the cooling leaves much to be desired, and also the fact that the dimensional accuracy and dimensional stability do not always meet the relevant requirements (which are continually rising), the use of such mould plates always presupposes that there will be suitably preshaped frames within which to build up the mould assembly, which may for example comprise longitudinal and transverse plates.

It is object of the invention to provide an ar rangement whereby the desired mould assembly can be built up within a frame of any of a variety of constructions.

According to the invention, there is provided a mould for the continuous casting of steel or other metal, comprising cooled metal mould plates which are held and braced in a frame, and which, when braced, define the mould cavity; wherein some at least of the mould plates each consist of two individual plates which abut against one an other at plane faces; one of these two individual plates defining the respective boundary of the mould cavity by means of its face which is turned away from the other individual plate; and the other individual plate making contact with the frame at its face turned away from the first individual plate.

This construction makes it possible to build up the mould assembly within a frame of any applica ble design. Thus, if the individual plate facing the frame has a plane outer face, these inserts can be inserted in an ordinary frame structure; and, if the individual plates have curved outer faces, it is at once possible to use mould plates according to the invention for those frame constructions in which the mould-plate-receiving portions are in the form of a circular arc, corresponding to the mould faces defining the mould cavity.

In addition to having this advantage of wide applicability, the present two-part mould plates have further advantages because, since the individual plate facing the frame can be of any desired shape, the cooling bores, cooling channels and/or water feed pipes can be varied as desired; they can for example be given a larger cross-section to improve the cooling effect. In this connection there is no need to change or replace the individual plate defining the mould cavity.

Furthermore, even with non-adjustable mould frames, the invention makes it possible to change the format of the cast strand, by changing the dimensions of the relevant individual plate(s). This possibility applies to the individual cast strand of a slab installation, for example, and again to "twin" casting, wherein two cast strands are drawn out in parallel.

It is of particular advantage that, in the case of the invention, the shaping inner faces of the individual plates facing the mould cavity can be plane and/or concavely/convexly curved, as required.

This ensures that they will be compatible with the mould constructions commonly employed at the present time.

Particular advantages accrue from the invention if, of the faces of the abutting individual plates which are turned away from one another, both are curved. The mould plates can then replace the known constructions in which cooling bores are formed in a one-piece straight mould plate and the plate is subsequently bent as a whole; in these known constructions the cooling of the plate in particular has left much to be desired.

Where rectangular casting formats are concerned, mould inserts are used which consist of "longitudinal" and "transverse" plates; and, in adjustable moulds, the transverse plates are arranged so as to be displaceable in the direction of the longitudinal plates, in order to change the cast format.

Here again, the invention can be applied with advantage, since the longitudinal and/or transverse plates, e.g. at least the longitudinal plates, can each consist of two individual plates abutting against one another at plane faces.

The present division of the mould plates into two individual plates makes it possible not only to vary the mould plates' external dimensions and shapes, but also to provide for various combinations of materials, thus satisfying one pre-condition for the highest possible casting qualities. in the case of the invention, the individual plates may indeed each be composed of substantially the same cop per materials; however, the two individual plates may instead be composed of copper materials rep resenting differing alloy compositions, depending on what properties are required in the individual plate defining the mould cavity and what proper ties are required in the individual plate facing the frame.

In this connection it is sometimes advantageous if the individual plates are actually composed of dissimilar materials. Thus, an individual plate facing a steel mould frame can likewise, be of steel, for reasons of strength, whereas the individual plate defining the mould cavity may be composed, for example, of a hardened copper alloy, in order to provide particularly favourable initial conditions for the cooling of the cast strand.

The two-part construction of the mould plate according to the invention permits better cooling conditions than in the abovementioned curved one-part plate with cooling bores; thus, according to a preferred feature of the invention, the individual plates may have cooling channels and/or water chambers in the region of their plane faces at which they abut against one another. However, these cooling channels or chambers can also be produced substantially more simply and therefore more cheaply, quite apart from the easier checking, in the event of faults in the cooling circuit, and simplified assembly.

The fitting of the individual plates can be carried out separately, or in any case can be simplified, because, as provided for in another preferred feature of the invention, these plates may be braced with respect to one another and in the frame by means of tension/expansion bolts which pass through the individual plate facing the frame and which are screwthreadedly engaged in the individual plate facing the mould cavity.

The plane at which the two individual plates abut may be sealed off from the outside, especially when, as is usual, the cooling channels or water chambers are open towards the said plane. For this purpose, means known per se, for example 0rings, can be used; however, cooling channels and/ or water chambers which are open towards the said plane and which are provided in the individual plate defining the mould cavity can also be covered by a copper foil which extends over the entire plate surface. This foil, which serves both to cover the cooling channels and/ or water chambers and to seal off the said plane from the outside, is of particular advantage when the individual plates are composed of different materials, for example steel and copper, since it can avoid the danger of corrosion occuring in the interface region when cooling water is present.

The invention will be explained in greater detail with reference to the accompanying diagrammatic drawings, in which; Figure l is a cross-section view showing a known plate construction; Figure 2 is a comparable view showing a mould plate for continuous-casting equipment according to the invention; Figure 3 is a fragmentary perspective view which illustrates a possible arrangement employing mould plates according to Figure 2; and Figure 4 is an end view which illustrates another possible arrangement employing mould plates according to the invention.

Figure 1 indicates diagrammatically a cross-section through a mould plate 1 for a slab mould, with an adjoining steel frame 3, as offered on the market at the at the present time. That face 2 of the mould plate 1 which is turned towards the mould cavity F is curved, according to the desired circular arc shape of the cast strand; however, the plate face 4 turned towards the steel frame 3 is also curved. This curvature of both of the faces 2 and 4 is basically governed by production considerations; a cooling bore as shown at 5 is made in the still straight plate 1, and the latter is subsequently bent. The support for the mould plate 1 in the steel frame 3 also has to be made curved, to correspond to its bent or curved face 4. The plate 1 is fastened to the frame 3 by means of expansion screws 6.

Apart from the considerable mechanical effort required in production, it may be noted that this known arrangement does not permit forms of plate differing from that of the mould plate 1, for example forms of plate with improved cooling properties, to be used with the frame 3.

A solution to this problem is provided by the construction according to the invention shown in Figure 2; this comprises a mould plate 7 composed of two individual plates 8 and 9, whose respective plane faces join together in a plane 10. The curvature of the face 11 turned towards the mould cavity F corresponds, for example, to that of the face 2 in Figure 1, and likewise the curvatures of the faces 4 and 12 are identical.Here the steel frame is the same as in Figure 1, and it is therefore designated once again by 3. instead of having cooling bores as shown in Figure 1, the Figure 2 embodiment of the invention has cooling slits 13 and water chambers 145 which are formed mechanically, for example, by milling, from the plane faces of the individual plates 8 and 9, and which open into these; their cross-sections and cross-sectional forms can easily be matched to the relevant particular requirements. The face 11 forming the mould cavity can be produced, and more particularly provided with the desired curvature, in a step completely independent of the formation of the cooling slits 13 and/or water chambers 14.When the face 11 is machined, moreover, there is no fear of adverse effects on cooling characteristics, for example as a result of the deformation of the cooling bore 5 during a bending process, as required in the case of Figure 1.

The individual plates 8 and 9 are held together and braced in the frame 3 by means of expansion screws 15, which are guided through the frame 3 and plate 9 and which end in blind holes in the plate 8. Sealing means 16, for example in the form of O-rings, seal off the joining plane 10 from the outside.

In the case of the invention, it is not essential for the individual plates to have only the shape illustrated in Figure 2; more particularly, the frame 3 and the adjoining face 12 of the plate 9 do not necessarily have to be curved. Thus, even a prior-art mould plate can be reproduced by an arrangement according to the invention which presents a curved face for the cast strand and a plane face for resting against the likewise plane frame. The present twopart design of the mould plate is decisive here, and this gives the invention a particularly wide range of use.

In this connection, reference may be made to embodiments of the invention which make it possible to change over from long-hole cooling to slit cooling, in mould plates, or to change the casting format in slab installations with non-adjustable moulds. This can apply not only to single casting, but also, as shown in Figure 3, to "twin" casting.

In the arrangement shown in Figure 3, there is a steel frame 17 wherein mould plates 18 and 19 are held and braced in the usual manner. If smaller casting formats are desired, the mould plates 18 and 19 forming the mould cavity can still be used, but individual plates 20 can be additionally inserted between the mould plates 19 and frame 17.

Thus, the now combined plates 19 and 20 form the effective mould plates which, in respect of their fastening in the frame, their cooling, and so forth, can be designed, for example, according to the embodiment of Figure 2, or even with a plane joining face between the frame 17 and the adjoining individual mould plate.

In the embodiment of the invention shown in Figure 4, longitudinal plates 23 having curved portions cooperate with transverse plates 22 which are plane. Here again, according to the invention, the longitudinal and/or transverse plates are composed of two individual plates abutting against one another at respective plane faces.

Instead of the mould cross-section shown in Figure 4, it is possible to provide for a mould crosssection in the form of a T, double T, U or L, for instance. As before, a two-part mould plate design is essential.

It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

Claims (14)

1. A mould for the continuous casting of steel or other metal, comprising cooled metal mould plates which are held and braced in a frame, and which, when braced, define the mould cavity, wherein some at least of the mould plates each consist of two individual plates which abut against one another at plane faces; one of these two individual plates defining the respective boundary of the mould cavity by means of its face which is turned away from the other individual plate; and the other individual plate making contact with the frame at its face turned away from the first individual plate.

2. A mould according to claim 1, wherein the mould cavity defining inner faces of the respective individual plates are plane and/or concavely/convexly curved.

3. A mould according to claim 1 or 2, wherein, of those faces of the abutting individual plates which are turned away from one another, both are curved.

4. A mould according to claim 1, 2 or 3, the mould comprising longitudinal and transverse plates, wherein at least the longitudinal plates each consist of two individual plates abutting against one another at plane faces.

5. A mould according to any of claims 1 to 4, wherein the individual plates are each composed of a copper material, and the copper materials are substantially the same.

6. A mould according to any of claims 1 to 4, wherein the two individual plates are composed of copper materials, but these represent differing alloy compositions.

7. A mould according to any of claims 1 to 4, wherein the two individual plates are composed of dissimilar materials.

8. A mould according to any of claims 1 to 7, wherein the individual plates have cooling channels and/or water chambers in the region of the said plane faces at which they abut one another.

9. A mould according to any of claims 1 to 8, wherein the said individual plates are braced with respect to one another and in the frame by means of tension/expansion bolts which pass through the individual plate facing the frame and which are screwthreadedly engaged in the individual plate facing the mould cavity.

10. A mould according to any of claims 1 to 9, wherein the plane at which the two individual plates abut is sealed off from the outside.

11. A mould according to claim 1, with individual plates composed of different materials, wherein cooling channels and/or water chambers are provided which open towards the plane at which the two individual plates abut, and are disposed in the individual plate defining the respective boundary of the mould cavity, and are covered by a copper foil which extends over the entire plate surface.

12. A mould according to claim 11, wherein the copper foil provides a sealing effect, between the individual plates, whereby the plane at which the two individual plates abut is sealed off from the outside.

13. A mould according to claim 1, substantially as described with reference to Figure 2, 3 or 4 of the accompanying drawings.

14. A process for the continuous casting of steel or other metal wherein a mould according to any of claims 1 to 13 is employed.