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(11) | EP 0 178 059 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | The production of metal strip |
| (57) 57 In the production of metal strip, continuous casting machines produce metal bar
which is coiled and the coils are kept in an enclosure providing a heat retaining
or heat improving environment until the coils are ready to be uncoiled one at a time
into a hot strip mill where the bar is reduced to strip. |
[0001] It has been proposed to continuously cast steel workpieces, referred to as bars, having a thickness within the range of 5 to 40 mm. A preferred thickness is 30 mm. It is intended that the cast bar will be passed through a finishing mill to reduce the bar to strip having a thickness in the range of 1 to 15 mm. The speed of production of a continuous casting machine producing metal bars is considerably less than the speed at which the material can be handled by a hot finishing mill. Particularly if the bars are to be joined end-to-end before being introduced into the finishing mill, the mill can only be operated after a number of bars have been produced by the continuous casting machine.
[0002] It is an object of the present invention to provide a method of, and apparatus for, producing metal strip in which the difficulty of the difference between the production speeds of a continuous casting machine and a hot finishing mill can.be overcome.
[0003] According to the first aspect of the present invention, in a method of producing metal strip, bars from a plurality of continuous casting machines are coiled as they are cast and, when each coil is of a predetermined length, the coil is severed from the bar being cast and is kept in a heat retaining or heat improving environment until, in turn, the coils are uncoiled into a hot finishing mill where the bar is reduced to strip.
[0004] By employing a plurality of continuous casting machines, a number of bars are produced simultaneously and the storage area required for storing the bars is reduced by coiling the bars as they are cast. The coils so formed are stored in a heat retaining or heat improving environment until they are ready to be uncoiled into the hot finishing mill. Although the cast bars are cooled after they leave the continuous casting mould, in order to solidify the metal, the bars retain a considerable amount of heat and, by coiling the bars, the heat lost from the bars is reduced to a minimum. This means that no further heat need be applied to the coil so long as most of the heat in the coil is retained while it is waiting to be uncoiled into the hot finishing mill. Alternatively, a small amount of heat may have to be introduced into the coil while it is waiting in order to keep it at a temperature suitable for uncoiling into the hot finishing mill.
[0005] It may be convenient for the tail end of the coil which is being uncoiled into the mill to be secured to the leading end of the next coil to be uncoiled into the mill so that the bars are fed continuously into the mill. The bars may be secured together by removing scale from the ends which are to be secured together, arranging the ends in overlapped relation and holding them in this overlapped relation until they pass between the rolls of the first stand of the hot finishing mill where the ends are welded together by the rolling action. Preferably the ends are shaped so that the overall thickness of the overlapped ends is substantially equal to the thickness of one of the bars.
[0006] According to a second aspect of the present invention, apparatus for use with a hot finishing mill comprises a plurality of continuous casting machines for producing metal bars; means for severing the bars; coilers for coiling the bars into coils of predetermined size; an enclosure providing a heat retaining or heat improving environment where the coils are stored, and an uncoiler for uncoiling the coils in turn into a hot finishing mill.
[0007] The invention is not simply that of producing a plurality of metal bars simultaneously and collecting them until sufficient have been produced to enable the hot finishing mill to be operated for an economic length of time. The invention resides in coiling the output from the continuous casting machines, keeping the coils in an environment where the heat in the coils is retained or improved, and uncoiling them in turn into the hot finishing mill. While the coils are waiting to be fed into the mill, they are kept in a heat retaining environment to minimise heat loss from the coils and, if necessary, heat can be applied to the coils before they are uncoiled and the bars fed into the hot finishing mill. The output from each continuous casting machine may be coiled in a separate Stelco coil box. When the coil is of a predetermined size, it is severed from the bar and lifted out of the Stelco box. It is kept in the enclosure until it is ready to be uncoiled and fed into the mill train.
[0008] 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 operation of the invention; and
Figure 2 is a section on the line II-II of Figure 1.
[0009] An uncoiling station where coils of metal bar are uncoiled and fed into a hot strip finishing mill is indicated by reference 1, the arrow 2 indicates the entrance to the hot finishing mill train. A plurality of continuous casting machines, say four machines, are indicated by reference numerals 5, 6, 7 and 8, respectively. Cast metal bar 9 having a thickness of between 5 and 40 mm, and conveniently 30 mm, is produced simultaneously by these continuous casting machines and the bar from each machine is fed directly into a separate coiler 5' - 8', respectively. The coilers may be of the well known Stelco type coil box. As soon as the coil is of the predetermined size, the coil is severed from the bar 9 being cast by a shear (not shown) and the coil 10 is taken from the coiler by a conveyor system 11. The coils taken from each of the coilers are passed along the conveyor system so that, in turn, they arrive at the uncoiler 1. At least the conveyor system 11, and preferably the coilers 5' - 8', and the uncoiler 1 are contained in an enclosure 12, which provides a heat retaining or heat improving environment for the coils. The enclosure is conveniently constructed from panels 13 of a thermal insulating material having a reflecting inner surface. Such panels are known as ENCO panels. Provision is also made for a heat toppingrup facility so that coils stored in the enclosure 12 can have their temperature raised to a temperature suitable for hot rolling.
[0010] By coiling the bars as they are cast, the surface area of the bar is reduced, thus reducing the heat loss considerably. While the coils are being conveyed by the conveyor system 11, they are in a heat retaining or heat improving environment so that, in some cases, no extra heat is required before the coils are ready to be uncoiled and for the bar to enter the hot finishing mill. In some cases, a small amount of heat is applied to the coils from electrical heating means. If desired, the tail end of the bar being fed into the hot finishing mill can be prepared for securement to the leading end of the next coil to be uncoiled. The preparation consists essentially of removing scale from the adjacent end portions which are to be secured together, arranging them in overlapped relation and holding them in this overlapped relation until they pass between the rolls of the first stand of the hot finishing mill. The rolling action causes the overlapped ends to be welded together. The ends to be overlapped may be shaped so that, when they are overlapped, the overall thickness is substantially equal to the thickness of one bar.
1. A method of producing metal strip from cast bar characterised in that bars (9)
from a plurality of continuous casting machines (5-8) are coiled as they are cast
and, when each coil is of a predetermined length, the coil (10) is severed from the
bar being cast and is kept in a heat retaining or heat improving environment (12)
until, in turn, the coils (10) are uncoiled into a hot finishing mill where the bar
is reduced to strip.
2. A method as claimed in claim 1, characterised in that the bars cast in the continuous
casting machines enter into said environment and are coiled in the environment.
3. A method as claimed in claim 1 or 2, characterised in that the coils are uncoiled
in the environment and the uncoiled bar leaves the environment and enters into the
hot finishing mill.
4. A method as claimed in any preceding claim, characterised in that the tail end
of the coil being uncoiled into the mill is secured to the leading end of the next
coil to be uncoiled into the mill so that the bars are fed continuously into the mill.
5. A method as claimed in claim 4, characterised in that the ends to be secured together
are arranged in overlapped relation and held in overlapped relation until they pass
between the rolls of the first stand of the hot finishing mill where the ends are
welded together by the rolling action.
6. A method as claimed in claim 5, characterised in that the ends of the bars to be
secured together are shaped prior to being arranged in overlapped relation so that
the-overall thickness of the overlapped ends is substantially equal to the thickness
of one of the bars.
7. Apparatus comprising a plurality of continuous casting machines for producing metal
bars (5-8); means for severing the bars; coilers (5'-8') for coiling the bars into
coils (10) of predetermined size; an enclosure (12) providing a heat retaining or
heat improving environment where the coils are stored; and an uncoiler (1) for uncoiling
the coils in turn into a hot finishing mill.
8. Apparatus as claimed in claim 7, characterised in that the coilers (5'-8') are
located within said enclosure.
9. Apparatus as claimed in claim 7 or 8, characterised in that the uncoiler (1) is
located within said enclosure.
10. Apparatus as claimed in claim 7, 8 or 9, characterised in the provision of apparatus
for securing the tail end of a coil being uncoiled to the leading end of the next
coil to be uncoiled.