WO1990014183A1

WO1990014183A1 - Continuous casting of metals

Info

Publication number: WO1990014183A1
Application number: PCT/GB1990/000792
Authority: WO
Inventors: Sandy Robertson Cochrane
Original assignee: Rautomead Limited
Priority date: 1989-05-19
Filing date: 1990-05-21
Publication date: 1990-11-29
Also published as: GB8911539D0; AU5663190A

Abstract

An apparatus is described for use in the continuous casting of metal. The apparatus comprises a crucible for molten metal (40) and a die device (2, 4) for cooling and forming the metal into ingots or castings. A valve means (12) comprises a fixed portion (34) on a recessed outlet in the crucible wall and a rotatable portion (42) on the die device housing (2), each portion (34, 42) having a plurality of valve ports (36, 38; 44, 46) which are moved into and out of alignment by rotating the die device (2, 4) by a remote operating means (48). A holding reservoir or well (11) is advantageously provided between the valve portions (34, 42) and the inlet to the die passage (10) of the device (2, 4).

Description

CONTINUOUS CASTING OF METALS The invention is concerned with improvements in or relating to the continuous casting of metals.

It is conventional practice in the continuous casting of metals to use an assembly comprising a crucible or furnace, a die device and cooling means. Should there be a requirement for changing the die device and cooling means, unacceptable interruptions occur in the continuity of operation, resulting in loss of efficiency. Such an operation usually involves emptying the crucible or furnace with all the consequent delays and disadvantages this entails. Moreover, on some occasions it is required to divert metal flow from the crucible away from the die device to drain the system into a reserve or dump crucible or other receptacle.

It is therefore an object of the present invention to provide an improved apparatus for the continuous casting of metals which reduces the difficulties mentioned above. The invention provides apparatus for use in the continuous casting of metals, comprising a chamber for molten metal and a die device including a passageway for receiving molten metal from said chamber for cooling, cooling means adapted to cool metal in said passageway prior to forming into metal ingots or castings, there being provided a valve means disposed between the chamber and the die device, wherein a first portion of said valve means is located at an outlet of the chamber and a second portion of the valve device is located at an inlet of said die device, each said valve portion being provided with valve ports, the construction and arrangement being such that upon rotational movement of the die device with respect to the chamber, communication between or closing-off of desired ports of said first and second valve portions is achieved.

Advantageously, said rotational movement of the die device takes place about a longitudinal axis thereof, confronting faces of said first and second valve portions being arranged in a radial plane with respect to said axis.

Preferably, the die device may comprise a holding reservoir or well positioned between said inlet and said passageway, said valve means being adapted to provide for said reservoir or well to be drained as required.

In an example of the invention to be described below, there are provided two through ports in said first valve portion one of which may also function as either a transfer port or a drain port. The second valve portion comprises two ports, capable of acting as transfer ports communicating with said reservoir or well to lead molten metal from the valve face to a longitudinal die bore of the die device. A drain port is also provided communicating with a passage leading from the valve means or from the holding reservoir or well to an external surface of the apparatus.

Conveniently the rotational movement of the die device is controlled by a remote lever arm, the cooling means of the die device being provided by a cooling jacket or other conventional means whereby solidification of the metal is achieved rapidly and completely within a primary length of the die bore. Conveniently, the die bore will be formed in a die member, which is held in a fixed housing or die holder.

It will be appreciated that the invention may be applied to any convenient mode of continuous casting, i.e. a horizontal, inclined or vertical arrangement.

There will now be described an example of an apparatus according to the invention. It will be understood that the description which is to be read with reference to the drawings, is given by way of example only and not by way of limitation.

In the drawings:-

Fig. 1 shows a part-sectional view of a cooler and die device;

Fig. 2 is a graph illustrating the fall in temperature to be achieved in the die device of Fig. 1;

Fig. 3 is a diagrammatic sectional view through the die device of Fig. 1 and the valve means according to the invention;

Fig. 4 shows the layout of ports in the valve face of first portion of the valve device and, superimposed thereon, the layout of ports in the valve face of the second valve portion, in a first, casting, condition; Fig. 5 shows the valve face of the second valve portion in a closed-off condition;

Fig. 6 shows the valve face of the second valve portion in a first drain/dump condition; and Fig. 7 shows the valve face of the second valve portion in a second drain/dump condition.

Figs. 1 and 3 show an assembly of a die device comprising a housing 2, and a cooling device 4 having a water inlet 6 and a water outlet 8. The housing encloses a die member 9 and at the left-hand side of the housing (as viewed in Figs. 1 and 3) is provided a liquid metal feed passage 10, a holding reservoir or well 11 and a valve device 12. If desired the reservoir 11 and passage 10 may be provided with a heater means (not shown) which eliminates any risk of premature solidification of metal from a crucible 14. The metal passes through the passage 10 and is then required to be cooled in a primary die bore 16 in accordance with the temperature/bore length graph in Fig. 2, which shows the position of the solidification front in the die bore with respect to Fig. 1. The primary die bore 16 is surrounded by a water jacket 17 of the cooling device 4 extending the full length of the die member 9 to ensure rapid heat extraction and complete conversion to the solid phase in the bore 16. It will be understood however that the cooling arrangement may be of any suitable type. Cooling and solidification is thus achieved and is completed well before a cast strand of metal 18 is finally expelled at an outlet 20.

The die device housing 2 and the valve device 12 are held in position by retaining bolts 22 securing a fixed thrust plate 24 in position to ensure sealing of the left hand end portion of the assembly in a recess 26 in the crucible wall 14, the die device housing 2 and cooler 4 being received in a sealed manner in an aperture provided with a cooling sleeve 28 and formed in a front plate 30 of the crucible, behind which plate is provided insulation means 32. The housing 2 also provides support for a securing arrangement for interchangeable die members 9 to be inserted in the housing. A secondary thrust plate 31 is bolted thereto, the bolts 33 also supporting a cooler clamp plate 35. The valve device 12 comprises two portions, including a first, fixed, portion 34 secured within the recess 26 and having two ports, a transfer port 36, a transfer/drain port 38 (see Fig. 4) both of which communicate with a crucible outlet 40 for molten metal portion 38 also being capable of communicating with a dump channel 41 in a manner which will be explained below. The present example uses an all-graphite construction for the crucible 14 and the die assembly, but in the case where the metal to be treated is aggressive to graphite, the valve faces may be provided with protective ceramic discs and the crucible and die assembly fitted with the appropriate ceramic insert or liner. Such an arrangement is described in European Patent Application No. 88306692.0 (Serial No. 0301763) . A second, valve, portion 42 shown superimposed in Figure 5 upon the portion 34 comprising a valve face in which are two casting ports 44 and 46, the portion 46 also being adapted to be used as a dump port 46.

The valve face 42 is formed on the left-hand, end face of the die device housing 2, which is capable of limited rotation about its longitudinal axis by means of a remote valve lever arm 48. Operation of the lever arm causes rotation of the entire assembly of die housing 2, die member 9 and cooling jacket 4 including clamping plates 33 and 35, so that the face 42 also rotates about centre point 50 as viewed in Figs. 4 - 7.

Fig. 4 shows casting ports 44 and 46 aligned with ports 36 and 38 for normal operation.

Fig. 5 shows a completely closed condition in which no port is in alignment with any other port. Since the die housing 2 is secured in the recess 26 of the crucible, removal of the die member 9 itself and the cooling jacket, if desired, may be accomplished for replacement or repair without loss of metal from the crucible.

Fig. 6 shows the valve device 12 in a reservoir-draining or dump condition wherein the ports 36 and 38 is closed (since the casting port 44 is out of alignment with port 36) and the port 44 is partially aligned with dump channel 41, sufficient to provide communication between the reservoir and a dump passage 48 in the crucible,wall. This passage 48 leads to exhaust so that metal may flow to another crucible or to a holding receptacle.

Figure 7 shows the valve device 12 in a crucible-draining condition in which ports 36 and 46 are out of alignment and both are therefore closed. However, the port 44 is partly aligned with both the port 38 and with the dump channel 41 so that metal from the interior of the crucible 40 may flow out through the passage 48 as indicated also in Figure 1 by the arrow A.

Various modifications may be made within the scope of the invention as defined in the following claims.

Claims

CLAIMS ;

1. Apparatus for use in the continuous casting of metal comprising a chamber for molten metal and a die device including a passageway for receiving molten metal from said chamber for cooling, cooling means adapted to cool metal in said passageway prior to forming into metal ingots or castings, there being provided a valve means disposed between the chamber and the die device, wherein a first portion of said valve means is located at an outlet of the chamber and a second portion of the valve device is located at an inlet of said die device, each said valve portion being provided with valve ports, the construction and arrangement being such that upon rotational movement of the die device with respect to the chamber, communication between or closing-off of desired ports of said first and second valve portions is achieved.

2. Apparatus as claimed in claim 1, wherein said rotational movement of the die device takes place about a longitudinal axis of said device and wherein confronting faces of said first and second valve portions are arranged in a radial plane with respect to said axis.

3. Apparatus as claimed in either one of claims 1 and 2, wherein there are provided at least two ports in said first valve port, at least one of which acts as a metal transfer portion during a casting operation and one of which is adapted to act as a drain port when required.

4. Apparatus as claimed in any one of the preceding claims wherein there are provided two ports in said second valve portions, at least one of which acts as a metal transfer port during a casting operation and one of which is adapted to act as a drain port when required.

5. Apparatus as claimed in either one of claims 1 and 2, wherein the die device comprises a holding reservoir or well positioned between said inlet and said passageway, said valve means being adapted to provide for the reservoir or well to be drained.

6. Apparatus as claimed in claim 6, wherein said first and said second valve portions are each provided with two through ports adapted to act as transfer ports for metal from the chamber for molten metal and the passageway of the die device, one of said ports of each valve portion being adapted alternatively to act as a drain port when aligned one with the other.

7. Apparatus as claimed in any one of the preceding claims, wherein a drain channel is provided in one of said valve portions to act as a drain outlet for said chamber for molten metal.

8. Apparatus as claimed in claim 8, wherein when said drain channel is to be used, the port of the second valve portion acting as a drain port is in communication both with the port of the first valve portion acting as a drain port and with the drain channel so that the chamber is drained via said holding reservoir or well.

9. Apparatus as claimed in any one of the preceding claims, wherein a lever arm is provided, remote from said valve portions, adapted to control said rotational movement of the die device.

10. Apparatus as claimed in claim 5, wherein heating means is provided adjacent the holding reservoir or well.