EP0234739B1

EP0234739B1 - The manufacture of metal strip

Info

Publication number: EP0234739B1
Application number: EP87300677A
Authority: EP
Inventors: Kenneth Thomas Lawson
Original assignee: Davy Mckee Sheffield Ltd
Current assignee: Davy Mckee Sheffield Ltd
Priority date: 1986-01-29
Filing date: 1987-01-27
Publication date: 1990-10-17
Anticipated expiration: 2007-01-27
Also published as: FI82619C; ATE57481T1; FI870364A0; DE3765553D1; FI82619B; EP0234739A1; FI870364A; GB8602163D0

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

This invention relates to a method of manufacturing metal strip by a rolling technique during which the width of the workpiece is increased.
It is known from EP-A 0 164 265 and JP-A 58-215 201 to hot roll a metal slab so that a groove is formed in each of the opposite faces of the slab and the width of the slab is increased; the width of each groove is increased to further increase the width of the slab and the slab is hot rolled to reduce it to substantially uniform thickness. The metal slab may have been formed originally in a continuous casting machine. It is envisaged in the EP specification that the mill stands having the rolls for producing the grooves and the mill having the rolls for reducing the slab to substantially uniform thickness are arranged in tandem.
In practice, it has been found that this arrangement is impracticable when rolling the workpiece down to strip.
It is an object of the present invention to provide a more practical method of manufacturing metal strip.
According to the present invention, a metal slab is formed in a continuous casting machine, it is hot rolled to form a groove in each of a pair of opposite faces and to increase the width of the slab and, thereafter, it is hot rolled to reduce it to substantially uniform thickness, characterised in that, on leaving the continuous casting machine, the slab is cooled and, after being re-heated, it is uncoiled into a spreading rolling mill where the grooves are formed and, on leaving the spreading mill, the slab is coiled and, after being re-heated, it is uncoiled into a multi-stand finishing mill where it is reduced to strip of predetermined gauge and width.
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.
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 drawings, in which:

Figure 1 shows diagrammatically the stages of the invention;
Figure 2 shows diagrammatically 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.

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.
As the capacities of the spreading and finishing mills are likely to be greater than that of a single continuous caster, a number of casters 1 are employed and the slabs produced by these casters are coiled by separate coilers 11. These coils are reheated in a furnace 13 and then passed to the mill where they are unwound, in turn, by an uncoiler 15 and passed through the spreading mill.
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 5A 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 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 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.
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.
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 it centre.
Finally, after passing through the multistand finishing mill, the workpiece is reduced to a gauge (thickness) of 2 mm and its width is 1150 mm.
In alternative forms, the workpiece 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 metal slab (3) is formed in a continuous casting machine (1), it is hot rolled to form a groove (17) in each of a pair of opposite faces and to increase the width of the slab (3) and, thereafter, it is hot rolled to reduce it to substantially uniform thickness, characterised in that, on leaving the continuous casting machine (1), the slab (3) is coiled and, after being re-heated, it is uncoiled into a spreading rolling mill (5) where the grooves (17) are formed and, on leaving the spreading mill (5), the slab (3) is coiled and, after being re-heated, it is uncoiled into a multi-stand finishing mill (9) where it is reduced to strip (7) of predetermined gauge and width.

2. A method as claimed in claim 1, in which the spreading mill (5) is a multi-stand mill and each roll of each stand is provided with a collar shaped to form a groove (17) in the slab (3), the collars on the rolls of succeeding stands being of greater length than those on the preceding stand whereby the width of the grooves (17) are progressively widened as the slab (3) is passed through the spreading mill (5).