GB2109722A

GB2109722A - Continuous casting apparatus for metals especially copper alloys

Info

Publication number: GB2109722A
Application number: GB08230438A
Authority: GB
Inventors: Bernard De Dreuille
Original assignee: Griset Ets
Current assignee: Griset Ets
Priority date: 1981-10-30
Filing date: 1982-10-25
Publication date: 1983-06-08
Also published as: FR2515545A1; JPS58135749A; FR2515545B1; DE3240115A1; DE3240115C2

Abstract

The apparatus which includes a mould, which comprises graphite walls (1, 2) backed by cooling elements (5, 6), and spacers (3, 4), is characterised in that it includes means of supplying a thermally conductive gas (11), to gaps (7, 15, 8, 16), which arise during operation, both between the walls (1, 2) and the cooling element (5, 6) (due to thermal distortion of the walls (1, 2)) and, also, between the walls (1, 2) and the ribbon (9) which is being cast (due to shrinkage of the ribbon on solidification). <IMAGE>

Description

SPECIFICATION Continuous casting die for metals especially copper alloys The present invention concerns a continuous casting die for metals, especially copper alloys.

In continuous casting apparatus and, in particular, for the continuous casting of copper alloys, the dies consist in general, of graphite parts which are in contact with cooling elements.

However, under the effect of thermal stress, the graphite parts bulge and deform and so become spaced from the cooling elements. This often reduces to a considerable degree the thermal exchange and, consequently, the cooling of the ribbon formed by casting. Now, as the speed of operation of a continuous casting apparatus is directly connected with the cooling, it is important that this cooling be as effective as possible. The object of the present invention is to provide a continuous casting die which enables the product to be effectively cooled during casting in order to accelerate the output of a continuous casting apparatus.

For this purpose, the invention concerns a die, characterised in that it includes a supply means for a conductive gas, connected to spaces subsisting during operation, between the die part and the cooling element and also, between the die part and the ribbon which is being cast.

By virtue of this die which permits the injection of a thermally-conductive gas between the die part and the cooling element and also between this die part and the product which is in the course of solidification, the thermal conductivity at the two heat-exchange interfaces is considerably improved. This permits a substantial increase in heat exchange and, consequently, the speed of solidification of the product during the course of casting.

The present invention will be described in more detail with the aid of the attached drawings in which: Figure 1 is a transverse section of a continuous casting die, taken along the line I-I of Figure 2; Figure 2 is a schematic view, partially in section on the line Il-Il of Figure 1, of a continuous casting die according to the invention.

According to Figures 1, 2, the die consists of two parts 1, 2 which are maintained spaced apart by spacer elements 3, 4 so as to form a die which, when inoperative, defines a channel of rectangular cross-section.

On the outside surface of each of the die parts 1, 2 is provided a cooling element 5, 6 which is in contact with the parts 1, 2 in order to exchange heat by conduction.

Now during the operation of the apparatus, under the effect of increases in temperature, the die parts 1, 2, adopt the curved shape shown and permit gaps 7, 8 to exist, in relation to the flat walls of the cooling elements 5, 6.

The cast ribbon 9 which, before cooling, when the cast material is still liquid, occupies the whole of the cross-section defined by the die parts 1, 2, 3, 4, becomes deformed under the effect of shrinkage as well as by the traction exerted to pull it through the die; the product then adopts a cross-section the thickness of which decreases towards the median plane of the die. A final product having a non-rectangular cross-section results, and this is not desired.

Figure 2 shows the longitudinal form of the cast product.

In this, figure, the liquid portion is represented by 9', the solid portion bearing the reference 9.

The product is extracted from the die in accordance with the arrow A.

The die is supplied by a crucible 10 filled with liquid metal.

According to the invention, the die includes a supply of thermally-conductive gas formed by a source of gas 11 having very good thermal conductivity connected by a conduit 12, 12' respectively to the die parts 1, 2 and by a conduit 13, 13' to the gaps 7, 8 which are formed between the die parts 1, 2 and the cooling elements 5, 6, that is to say the gaps 7, 8.

At the front of the die, there may possibly be provided a collector 14 which recovers the thermally conductive gas in order to return it to the reservoir 11.

The possible circulation of the thermallyconductive gas is represented by the arrows B.

The conductive gas injected into the die parts 1, 2 diffuses through the dies and escapes either into the gaps 7, 8 or into the gaps 15, 16 which subsist between the walls of the die and the corresponding walls of the solidified product 9.

At the outlet of the die, there is provided a collector 14 which recovers the conductive gas which escapes from the gaps 7, 1 5, 8, 16 to return this gas to the reservoir 11.

Two methods of operation are possible. The first method of operation consists in directing conductive gas into the gaps 7, 15, 8, 16 without circulating this gas (leaks being recovered by the collector 14). Under these conditions, the gas acts as a heat conductor promoting exchange by conductivity across the interfaces: moulded product 9/die part 1/cooling element 5.

The gas used in this case can be a gas such as hydrogen or helium, which are excellent conductors.

The second mode of operation consists in circulating the conducted gas. In this case there is utilised not only the thermal conductivity of the gas which promotes heat exchange at the abovementioned gaps, but also removal of heat by circulation of this gas which is passed into a heat exchanger which is not shown, etc.

In a general manner, the means of the invention, such as described above, are applicable to all types of dies regardless of the number of parts which they comprise.

1. Continuous casting die for metals and, especially for copper alloys, said die comprising elements of graphite defining the cross-section of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Continuous casting die for metals especially copper alloys The present invention concerns a continuous casting die for metals, especially copper alloys. In continuous casting apparatus and, in particular, for the continuous casting of copper alloys, the dies consist in general, of graphite parts which are in contact with cooling elements. However, under the effect of thermal stress, the graphite parts bulge and deform and so become spaced from the cooling elements. This often reduces to a considerable degree the thermal exchange and, consequently, the cooling of the ribbon formed by casting. Now, as the speed of operation of a continuous casting apparatus is directly connected with the cooling, it is important that this cooling be as effective as possible. The object of the present invention is to provide a continuous casting die which enables the product to be effectively cooled during casting in order to accelerate the output of a continuous casting apparatus. For this purpose, the invention concerns a die, characterised in that it includes a supply means for a conductive gas, connected to spaces subsisting during operation, between the die part and the cooling element and also, between the die part and the ribbon which is being cast. By virtue of this die which permits the injection of a thermally-conductive gas between the die part and the cooling element and also between this die part and the product which is in the course of solidification, the thermal conductivity at the two heat-exchange interfaces is considerably improved. This permits a substantial increase in heat exchange and, consequently, the speed of solidification of the product during the course of casting. The present invention will be described in more detail with the aid of the attached drawings in which: Figure 1 is a transverse section of a continuous casting die, taken along the line I-I of Figure 2; Figure 2 is a schematic view, partially in section on the line Il-Il of Figure 1, of a continuous casting die according to the invention. According to Figures 1, 2, the die consists of two parts 1, 2 which are maintained spaced apart by spacer elements 3, 4 so as to form a die which, when inoperative, defines a channel of rectangular cross-section. On the outside surface of each of the die parts 1, 2 is provided a cooling element 5, 6 which is in contact with the parts 1, 2 in order to exchange heat by conduction. Now during the operation of the apparatus, under the effect of increases in temperature, the die parts 1, 2, adopt the curved shape shown and permit gaps 7, 8 to exist, in relation to the flat walls of the cooling elements 5, 6. The cast ribbon 9 which, before cooling, when the cast material is still liquid, occupies the whole of the cross-section defined by the die parts 1, 2, 3, 4, becomes deformed under the effect of shrinkage as well as by the traction exerted to pull it through the die; the product then adopts a cross-section the thickness of which decreases towards the median plane of the die. A final product having a non-rectangular cross-section results, and this is not desired. Figure 2 shows the longitudinal form of the cast product. In this, figure, the liquid portion is represented by 9', the solid portion bearing the reference 9. The product is extracted from the die in accordance with the arrow A. The die is supplied by a crucible 10 filled with liquid metal. According to the invention, the die includes a supply of thermally-conductive gas formed by a source of gas 11 having very good thermal conductivity connected by a conduit 12, 12' respectively to the die parts 1, 2 and by a conduit 13, 13' to the gaps 7, 8 which are formed between the die parts 1, 2 and the cooling elements 5, 6, that is to say the gaps 7, 8. At the front of the die, there may possibly be provided a collector 14 which recovers the thermally conductive gas in order to return it to the reservoir 11. The possible circulation of the thermallyconductive gas is represented by the arrows B. The conductive gas injected into the die parts 1, 2 diffuses through the dies and escapes either into the gaps 7, 8 or into the gaps 15, 16 which subsist between the walls of the die and the corresponding walls of the solidified product 9. At the outlet of the die, there is provided a collector 14 which recovers the conductive gas which escapes from the gaps 7, 1 5, 8, 16 to return this gas to the reservoir 11. Two methods of operation are possible. The first method of operation consists in directing conductive gas into the gaps 7, 15, 8, 16 without circulating this gas (leaks being recovered by the collector 14). Under these conditions, the gas acts as a heat conductor promoting exchange by conductivity across the interfaces: moulded product 9/die part 1/cooling element 5. The gas used in this case can be a gas such as hydrogen or helium, which are excellent conductors. The second mode of operation consists in circulating the conducted gas. In this case there is utilised not only the thermal conductivity of the gas which promotes heat exchange at the abovementioned gaps, but also removal of heat by circulation of this gas which is passed into a heat exchanger which is not shown, etc. In a general manner, the means of the invention, such as described above, are applicable to all types of dies regardless of the number of parts which they comprise. CLAIMS

1. Continuous casting die for metals and, especially for copper alloys, said die comprising elements of graphite defining the cross-section of the cast ribbon, these die parts being surrounded by cooling elements which abut against at least the main surfaces of the die, the die being characterised in that it includes supply means for a conductive gas connected to gaps which subsist during operation, between the die part and the cooling element and also between the die part and the ribbon which is being cast.

2. Die according to Claim 1, characterised in that the thermally-conductive gas is a gas and that the injection thereof into the gaps takes place at least partially through the die parts.

3. Apparatus according to either Claim 1 or 2, characterised in that it includes a collector at the outlet of the die, to recover the thermallyconductive gas.

4. Apparatus according to Claim 1, characterised in that the thermally-conductive gas is selected from the group consisting of gases such as hydrogen or helium.