The manufacture of metal strip

Abstract

 In a method of manufacturing metal strip (7), a workpiece produced in a continuous casting machine (1) is passed through a spreading mill (5) where grooves (17) are formed in a pair of opposite faces of the workpiece and thereafter the workpiece is rolled between the rolls of a multi-stand finishing mill (9) to reduce the workpiece to strip of the required width and gauge.

Description

[0001] This invention relates to a method of manufacturing metal strip by a rolling technique during which the width of the workpiece is increased.

[0002] According to the present invention, in a method of manufacturing metal strip, a continuously cast metal workpiece is hot rolled between the rolls of a spreading mill to roll a groove in each of a pair of opposite faces of the workpiece and thereafter the workpiece is rolled in a multi-stand finishing mill to reduce the thickness and increase the width of the workpiece to form strip of a predetermined gauge and width.

[0003] The required change in width is brought about by first forming the grooves in the opposite faces of the workpiece, which causes the width of the workpiece to be increased and thereafter by rolling the grooves out of the workpiece in the finishing mill to increase the width of the workpiece further.

[0004] The workpiece may be passed directly from the continuous caster to the multi-stand spreading mill but it is likely to be more convenient to coil the output from the continuous caster and, at a later stage, to re-heat the coil, uncoil it and pass the workpiece between the stands of the multi-stand spreading mill.

[0005] The workpiece leaving the spreading mill may be passed directly into the finishing mill but it is likely to be more convenient if the workpiece leaving the spreading mill is coiled and subsequently, after being re-heated if necessary, it is uncoiled into the finishing mill.

[0006] In order that the invention may be more readily understood, it will now be described, by way of example only, with reference to the accompanying drawing, in which:-

Figure 1 shows diagramatically the stages of the invention;

Figure 2 shows diagramatically a workpiece being passed through a multi-stand spreading mill; and

Figure 3 is an exaggerated plan of the workpiece as it passes through the spreading mill.

[0007] Thin metal slabs are cast in a continuous casting machine 1. The thin slab 3 passes through the stands of a multi-stand spreading mill 5 where the width of the slab is increased and, on leaving the spreading mill, the slab is rolled to strip 7 of the required gauge and of still further increased width in a finishing mill 9.

[0008] As the capacities of the spreading and finishing mills are likely to be greater than that of a single continuous caster, it is envisaged that a number of casters 1 would be employed and the slabs produced by these casters would be coiled by separate coilers 11. These coils would be re-heated in a furnace 13 and then passed to the mill where they would be unwound in turn by an uncoiler 15 and passed through the spreading mill into the finishing mill.

[0009] Referring to Figure 2, the uncoiler 15 carries a coil of metal slab 3 previously produced in one of the continuous casters. The coil is uncoiled and passed into the spreading mill 5, shown as having five two-roll stands. The pair of rolls 3A constituting the first stand of the spreading mill are each provided with a collar and the collars are shaped to form respective grooves 17 in the opposite faces of the slab. The provision of the grooves 17 cause the width of the slab to be increased slightly. As the slab passes through the succeeding stands of the spreading mill, the rolls of which have collars of increased width, the grooves 17 are progressively widened and thereby increase the width of the slab. In Figure 3, reference 19 indicates the section of the grooved slab as it leaves the last stand of the spreading mill. The slab then either passes directly into the stands of the multi-stand finishing mill 9 where first the thickened edge portions of the slab are reduced in thickness thereby widening the slab still further and thereafter the slab is progressively reduced to the required gauge. Alternatively the grooved slab leaving the spreading mill 5 is coiled in a coiler 21 and subsequently re-heated in a furnace 23 and uncoiled by an uncoiler 25 into the finishing mill 9.

[0010] A typical example of the process of the invention is for the or each continuous casting machine 1 to produce a workpiece of 50 mm thickness and 1000 mm width.

[0011] This workpiece is passed through the spreading mill and, when it leaves the spreading mill, it is still 50 mm thick at the edges and reduced to 25 mm at its center.

[0012] Finally, after passing through the multi-­stand finishing mill, the workpiece is reduced to a gauge (thickness) of 2 mm and its width is 1150 mm.

[0013] In alternative forms, the workpieces as cast in the continuous casting machines may have a width of between 600 -1900 mm and a thickness of between 30 - 75 mm.

Claims

1. A method of manufacturing metal strip in which a continuously cast metal workpiece is hot rolled between the rolls of a spreading mill to roll a groove in each of a pair of opposite faces of the workpiece and thereafter the workpiece is rolled in a multi-stand finishing mill to reduce the thickness and increase the width of the workpiece to form strip of a predetermined gauge and width.

2. A method as claimed in claim 1, in which the continuously cast workpiece is passed directly from the continuous caster to the spreading mill.

3. A method as claimed in claim 1, in which the continuously cast workpiece is coiled and subsequently, after being re-heated if necessary, it is uncoiled into the spreading mill.

4. A method as claimed in claim 1, 2 or 3, in which the spreading mill is a multi-stand mill and the workpiece is passed successively between the rolls of the stands to roll said grooves in the opposite faces of the workpiece and to progressively increase the width of the grooves.

5. A method as claimed in any preceding claim, in which the workpiece leaving the spreading mill is passed directly into the finishing mill.

6. A method as claimed in any of the claims 1 to 4, in which the workpiece leaving the spreading mill is coiled and subsequently, after being re-heated if necessary, it is uncoiled into the finishing mill.

Drawing