METAL STRIP PRODUCTION

Abstract: A multi-strand continuous caster (2 or 34) has downstream furnace means (12 or 36) for receiving cast strands (E, F), and a hot strip rolling mill (28) downstream of the furnace means for rolling the strands to strip, said furnace means including transfer means comprising a roller table (14) of sufficient width to accommodate at least two parallel bars, with support means (16) movable between the rollers, to disengage a bar from the rollers and to enable it to be transferred between two alternative path positions.

Description: METAL STRIP PRODUCTION This invention relates to the production of metal strip from molten metal. Continuous casters which are capable of casting metal bars are known. Usually the caster has a mould arranged with the longitudinal axis of its mould passage vertical and the cast bar exiting the mould is turned through 90° to move in a horizontal direction. The mould may have a curved mould passage which causes the cast bar to leave the mould in a direction inclined in the vertical and means are provided downstream of the mould to complete the change of direction of movement of the cast bar to the horizontal direction. After casting, the bar is cut into convenient lengths which are subsequently rolled one at a time in a multistand hot strip mill to produce strip of the required gauge. Between the caster and the rolling mill, furnace means are provided for maintaining the temperature of the cast bars to a value suitable for entry to the hot strip rolling mill. The capacity of the hot strip rolling mill may be greater than the capacity of the continuous caster and so it may be advantageous to provide two continuous casters and the bars from each of the two casters are then rolled alternately in the hot strip rolling mill. However this does require additional handling facilities to transfer the bars and supply them to the input path of the mill at the required rate. Alternatively a "multistrand" caster may be provided which produces at least two parallel strands and thus a series of pairs of adjacent cast bars. This has the considerable advantage that the installation is much more compact, but suitable handling means are still required for receiving the bars from the caster and supplying them to the mill. According to the present invention an installation for the production of metal strip comprises a multi-strand continuous caster for the production of strands from molten metal, furnace means downstream of the caster for receiving cast strands, and a hot strip rolling mill downstream of the furnace means for rolling the strands to strip, the continuous caster being arranged to produce at least two parallel strands which then pass through means for cutting into separate bars; said furnace means including transfer means comprising a roller table of sufficient width to accommodate at least two parallel bars, with support means movable between the rollers, to disengage a bar from the rollers and to enable it to be transferred between two alternative path positions. Preferably, the arrangement is such that a first one of the strand paths is in line with the rolling mill, the transfer means being adapted to transfer a bar from the or another path, into the in-line position, each time a bar from the said first path has been transferred into the rolling mill. With a caster of two separate strands, a two row furnace is preceded by an "Enco transfer" which is preceded by separate strand furnaces and which is arranged to move the bar from the second strand of the caster into an intermediate position more closely adjacent the path of the first strand, so that the two row furnace can be made as narrow as possible. In a typical installation, in order to optimise the output of the mill, it is necessary to allow for a minimum output of 2 to 3 million tons per year, whereas each strand from a typical continuous caster will produce approximately 1 million tons per year. Consequently, if the output from a twin strand caster can be efficiently supplied to a single rolling mill, it is possible to obtain a much more efficient usage of the plant than could otherwise be achieved. With a split mould caster an "Enco transfer" is not required because the strand paths are initially close together within a single furnace which also incorporates the aforesaid transfer means. Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic plan view of the layout of a first type of continuous casting installation in accordance with the invention; Figure 2 is a vertical cross-section on the line X-X of Figure 1 (and also in Figure 3) showing the transfer means; and Figure 3 is a diagrammatic plan view of a second type of installation also incorporating the transfer means of Figure 2. Referring to Figure 1 , a twin strand caster 2 receives a molten metal and produces a pair of parallel strands between 50 and 100 mm thickness, which are cast vertically and then turned through 90° into horizontal position. The bars pass through respective pairs of shears 4, which shear them into lengths, each of which enter a respective tunnel furnace 6 or 8. These furnaces maintain the temperature of the bars, so that they do not cool down too much before entering the rolling mill. As can be seen from the drawing, one of the furnaces 6 is in alignment with the axis of the remainder of the path through the rolling mill, whilst the other furnace 8, is offset by the normal spacing between the two outputs of the twin strand caster. As indicated on the drawing, this results in an initial pair of bars A and B being positioned in the two furnaces. The first pair of furnaces are followed by an "Enco transfer" which has a "fixed Enco station" 10 aligned with the main path of the mill, i.e., in alignment with the bar B, and an "Enco transfer station" 11 in parallel with it, which is adapted to receive the bar in position A. While the bar at position B is moved up to position D in the "fixed Enco station" 10, the bar in position A is moved forward into the "Enco transfer station" 1 1 which then moves it laterally into position C, so that the two bars are then positioned on approximately 1900 mm centres. The "Enco stations" are provided, in a known fashion, so as to enable the bars to be transferred between different positions, without undue heat loss. The "Enco transfer " is followed by a "two row furnace" 12 which is shown in cross- section in Figure 2. The two bars at positions C and D are moved forward into the furnace 12, so as to occupy adjacent positions E and F where they are supported on a roller table 14, and this is provided with retractable fingers 16 which enable a bar at position E to be traversed into position F, as will be described in more detail below. The fingers are supported on "lift/lower" arms 18, so as to enable the bar at position E to be lifted off the rollers 14, and the arms are in turn mounted on a transfer means 20 which can be traversed laterally to provide the necessary movement between positions E and F. In operation, after the initial pair of bars has been transferred into positions C and D, in the "Enco stations" 10, 1 1 and then moved forward into positions E and F, the bar in position E is raised on the fingers 16 to clear the rollers so that the bar in position F can be moved forward again to position G, in a single row furnace 22, so as to continue down the line. The fingers 16 carrying the bar at E are then traversed by lateral driving of the transfer means 20 so as to move the bar from E into the in-line position at F, following which the fingers are lowered and returned to their starting position. The rollers are then actuated again so that this bar follows the previous one into position G, and thus the next pair of bars waiting in positions C and D can now be moved forward (at the same time if necessary) into positions E and F. The process is now repeated by raising the new bar at E to clear the rollers while the bar now occupying position F is moved forward to position G, and so on. It will thus be appreciated that this arrangement allows each of the bars occupying the alternative positions C and D to be alternately shifted to position F, ready for transfer into the single row furnace 22 at position G. The furnace 22 is then followed by further conventional stages of the rolling mill, including a rougher/edger station 24, and a further furnace 26 defining a position H, leading to finishing strands 28 which are in turn followed by a pair of down coilers 30 and 32. In the example shown, the bars are cast at approximately 50 mm thick and 900 to 1350 mm wide, and enter the shears at 3 to 5 metres per minute. The shears are arranged to cut the strands into 25 metre long pieces, and the rolled strip will finally issue from the finishing strands at 5 - 12 metres per second. It is preferable to provide two down coilers 30 and 32, which can be shifted into receiving position alternately. It will also be appreciated that the size of the entire installation can be minimised, particularly in terms of its width, because the two strands from the twin strand caster are approximately 8 metres apart at the initial stage A and B whereas alternative arrangements to produce the same quantity of output would require (for example) two separate casters which have to be approximately 30 metres apart. The use of "Enco transfer" also enables the two row furnace to be made much narrower than would otherwise be possible, by arranging for positions C and D to be on 1900 mm centres, rather than on the initial 8 metre centres. A further simplification is achievable by means of the arrangement of Figure 3, in which a "split-mould" caster 34 is used so that the two strands are very close together. For example, the mould may have a central partition which is only 150-300 mm wide so that the strands are correspondingly spaced, so that the "Enco-transfer" of Figure 1 can be dispensed with. The construction of the furnace 36 at the output of the caster can also be much simpler since the two strands and therefore the cut bars A, B will be at a constant spacing, and only the transfer means 14, 16, 18, 20 for the positions E, F (parallel/in-line) transfer will be required. A further advantage of the "split-mould" caster is that a single wide strand can be produced by removing the central partition.

Claims: CLAIMS 1. An installation for the production of metal strip comprising a multi-strand continuous caster for the production of strands from molten metal, furnace means downstream of the caster for receiving cast strands, and a hot strip rolling mill downstream of the furnace means for rolling the strands to strip, the continuous caster being arranged to produce at least two parallel strands which then pass through means for cutting into separate bars; said furnace means including transfer means comprising a roller table of sufficient width to accommodate at least two parallel bars, with support means movable between the rollers, to disengage a bar from the rollers and to enable it to be transferred between two alternative path positions. 2. An installation as in Claim 1 , wherein the arrangement is such that a first one of the strand paths is in line with the rolling mill, the transfer means being adapted to transfer a bar from the or another path, into the in-line position, each time a bar from the said first path has been transferred into the rolling mill. 3. An installation as in Claim 1 or Claim 2, with a caster of two separate strands and wherein a two row furnace is preceded by an "Enco transfer" which is preceded by separate strand furnaces and which is arranged to move the bar from the second strand of the caster into an intermediate position more closely adjacent the path of the first strand, so that the two row furnace can be made as narrow as possible. 4. A twin strand caster installation for the production of metal strip substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings. 5. A split mould caster installation for the production of metal strip substantially as hereinbefore described with reference to Figures 3 and 2 of the accompanying drawings.

Inventors: HAYNES RALPH GLADWIN, HAYNES, RALPH, GLADWIN
Applicants: HAYNES RALPH GLADWIN, POSEC EUROP LIMITED, HAYNES, RALPH, GLADWIN, POSEC-EUROPE LIMITED
Application year: 1998
Main classification: B21B1
IPC codes: B21B1, B21B45, B22D11, C21D9, F27B9, F27D3