U.S. patent application number 09/171735 was filed with the patent office on 2001-07-12 for process for manufacturing hot rolled steel strips.
Invention is credited to HOPPMANN, HANS, QAMBUSCH, HERBERT, SCHONBECK, JOACHIM.
Application Number | 20010007267 09/171735 |
Document ID | / |
Family ID | 7793281 |
Filed Date | 2001-07-12 |
United States Patent
Application |
20010007267 |
Kind Code |
A1 |
SCHONBECK, JOACHIM ; et
al. |
July 12, 2001 |
PROCESS FOR MANUFACTURING HOT ROLLED STEEL STRIPS
Abstract
The invention is directed to a process for the production of
hot-rolled steel strip from continuously cast precursor strip in at
least two deformation stages, each deformation stage having one or
more roll stands, wherein initial rolling is carried out in the
first deformation stage at the output speed at which the precursor
strip exits from the continuous casting plant and the intermediate
strip thus produced is coiled prior to the second deformation stage
at the output speed at which it exits from the first deformation
stage, wherein the coil is uncoiled after reaching the coil weight
and is supplied to the second deformation stage for finish rolling
at the initial roll pass speed and is then coiled in the desired
finished coil sizes. In the first deformation stage, at least 40
tons of a casting sequence of the continuous casting plant is
rolled out in endless manner to form intermediate strip and is
coiled to form an intermediate coil without severing, and after
more or less endless finish rolling the intermediate strip of this
intermediate coil is severed according to the desired coil weights
and coiled as finished strip only following the second deformation
stage.
Inventors: |
SCHONBECK, JOACHIM;
(DUSSELDORF, DE) ; QAMBUSCH, HERBERT; (RATINGEN,
DE) ; HOPPMANN, HANS; (DUSSELDORF, DE) |
Correspondence
Address: |
COHEN PONTANI LIEBERMAN & PAVANE
551 FIFTH AVENUE
SUITE 1210
NEW YORK
NY
10176
|
Family ID: |
7793281 |
Appl. No.: |
09/171735 |
Filed: |
December 4, 1998 |
PCT Filed: |
April 15, 1997 |
PCT NO: |
PCT/DE97/00787 |
Current U.S.
Class: |
148/601 ;
148/602 |
Current CPC
Class: |
B21B 45/004 20130101;
B21B 1/463 20130101; B21C 47/02 20130101 |
Class at
Publication: |
148/601 ;
148/602 |
International
Class: |
C21D 008/02; C21D
009/52 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 23, 1996 |
DE |
196 17 856.8 |
Claims
1. Process for the production of hot-rolled steel strip from
continuously cast precursor material in at least two deformation
stages, each deformation stage having one or more roll stands,
wherein the precursor material is rolled out in endless manner to
form an intermediate strip in the first deformation stage at the
output speed at which the precursor material exits from the
continuous casting plant, and prior to the second deformation stage
at the output speed at which it exits from the first deformation
stage the intermediate strip is coiled without severing to form an
intermediate coil and is subsequently uncoiled in order to supply
the intermediate strip to more or less endless finish rolling,
after which this intermediate strip is severed in accordance with
the desired coil weights and is coiled as finished strip,
characterized in that at least 40 tons of a casting sequence of the
continuous casting plant is cast to form precursor strip and is
rolled out in the first deformation stage to form intermediate
strip whose metallurgical characteristics are changed by changing
the temperature control prior to coiling the intermediate coil
and/or prior to the second deformation stage and by flexible speed
control within an intermediate coil length.
2. Process for the production of hot-rolled steel strip from
continuously cast precursor strip according to claim 1,
characterized in that the geometrical characteristics of the
finished coils produced from an intermediate coil are changed by
suitable adjustment of the rolling parameters during the
deformation of the intermediate strip within the second deformation
stage.
3. Process for the production of hot-rolled steel strip from
continuously cast precursor strip according to claims 1 and 2,
characterized in that the coiling of the intermediate strip to form
an intermediate coil is carried out on a mandrel.
4. Process for the production of hot-rolled steel strip from
continuously cast precursor strip according to claims 1 and 2,
characterized in that the coiling of the intermediate strip to form
an intermediate coil is carried out without a mandrel.
5. Process for the production of hot-rolled steel strip from
continuously cast precursor strip according to claims 1 to 4,
characterized in that at least the edges of the intermediate strip
are protected from cooling during the coiling of the precursor
strip to form the intermediate coil.
Description
[0001] The invention is directed to a process for the production of
hot-rolled steel strip from continuously cast precursor strip in at
least two deformation stages, each deformation stage having one or
more roll stands, wherein initial rolling is carried out in the
first deformation stage at the output speed at which the precursor
strip exits from the continuous casting plant and the intermediate
strip thus produced is coiled prior to the second deformation stage
at the output speed at which it exits from the first deformation
stage, wherein the coil is uncoiled after reaching the coil weight
and is supplied to the second deformation stage for finish rolling
at the initial roll pass speed and is then coiled in the desired
finished coil sizes.
[0002] A process of the type mentioned above is described, for
example, in the German Patent 38 40 812 C2 and has become known in
technical literature as the ISP process. An essential
characteristic of this process is the two-stage rolling process in
which the first deformation stage is carried out directly following
the casting machine at casting speed and the second deformation
stage is carried out at an appreciably higher rolling speed. These
two rolling process stages are linked by an intermediate coiling
system in the form of a coiling furnace in which the continuously
cast slab is coiled after being rolled down, wherein the weight of
the coil corresponds to the desired finished coil weight. The
strand which is initially generated in an endless manner is
therefore divided following the first deformation stage when the
coil weight reached in the coiling furnace is equal to the weight
of the finished coil after rolling down in the second deformation
stage.
[0003] When rolling hot strip according to this process, the
threading of the strip head into the coiler imposes a limit on the
rolling speed because there is a risk at very high speeds that the
strip head will run up on the run-out table. When the strip head is
caught in the coiler, the rolling speed could be increased as much
as desired in practice within the framework of possibilities of the
plant and technical requirements.
[0004] In order to overcome the above-described limitation of
rolling speed, methods have been developed for endless rolling
which rely on the principle of joining the precursor strips before
entering the finishing train. For example, it is proposed that a
plurality of precursor strips are welded together end to end in
order to be able to reduce the threading-in processes and enable
more or less endless rolling. However, welding the precursor strips
together requires complex installations and likewise limits the
possible rolling speed.
[0005] In the process on which the invention is based, as was
already mentioned, precursor strips are produced by the continuous
casting process and wound into coils whose weight corresponds to
the weight of the finished strip coil. For this purpose, the
precursor strip is severed after reaching the coil weight in the
intermediate coiling station and is accordingly disconnected from
the casting plant so that the strip can be uncoiled in the
finishing train at high speed. However, because of the
above-described risk when threading the strip head into the coiler,
rolling speeds are limited so that considerable problems occur
specifically when rolling thin hot strip in the order of magnitude
of less than 1.5 mm. Conventional plants are therefore incapable of
producing thin hot strip in large quantities.
[0006] Proceeding from the aforementioned problems and
disadvantages of the prior art, it is the object of the present
invention to propose a process for producing hot-rolled steel strip
in which very thin strip can also be rolled in a reliable manner at
high final rolling speeds.
[0007] According to the invention, this object is met in that in
the first deformation stage at least 40 tons of a casting sequence
of the continuous casting plant is rolled out in endless manner to
form intermediate strip and is coiled to form an intermediate coil
without severing, and in that after more or less endless finish
rolling the intermediate strip of this intermediate coil is severed
according to the desired coil weights and coiled as finished strip
only following the second deformation stage.
[0008] In a casting plant of the type mentioned above followed by a
pre-deformation group, precursor material is produced by an endless
rolling process for finishing in the finishing train. Contrary to
the usual mode of operation in which this precursor material is cut
into parts corresponding to the subsequent coil weights, the
precursor material with the intended object of endless rolling is
not cut behind the deformation group, but rather is wound, without
cutting, into an intermediate coil comprising a plurality of
finished coils. Out of this intermediate coil, a plurality of coil
lengths are then finished in an endless rolling process in the
finishing train. The size of the intermediate coil is limited only
by the mechanical configuration of the coiling unit and the rolling
time in which the finishing train can be operated without changing
rolls. With suitable coiling devices, it is entirely possible to
carry out endless rolling of whole casting sequences of a
continuous casting plant, but at least substantially greater
tonnages can be rolled out than would be possible in plants
according to the prior art.
[0009] The process steps according to the invention appreciably
increase the buffer capacity of the intermediate coiling system.
With a coiling capacity of approximately 100 tons, for example, the
buffer capacity would increase to 60 minutes per intermediate coil.
Due to the higher final rolling speeds which are made possible by a
procedure of the type mentioned above, hot strip with thicknesses
of less than 1.2 mm can easily be produced in an endless manner.
The yield of the plant is improved because the typical rough-rolled
end or rolling tongue which must be removed before further
processing develops only for the start of the first coil and the
end of the last coil behind the finishing train. Moreover, the
quality of the rolling stock can be improved because the non-steady
state of the initial pass impact or shock takes place only once in
the first coil.
[0010] The winding of the intermediate strip to form an
intermediate coil can be carried out with or without mandrel.
Further, according to another feature of the invention, the
metallurgical characteristics within an intermediate coil length
can be changed by changing the temperature control prior to winding
the intermediate coil and/or prior to the second deformation stage
and by flexible speed control.
[0011] In a further development of the invention, the geometrical
characteristics of the finished coil produced from an intermediate
coil are changed by suitable adjustment of the rolling parameters
during the deformation of the intermediate strip within the second
deformation stage.
[0012] It is advantageous when at least the edges of the
intermediate strip are protected from cooling during the coiling of
the precursor strip to form the intermediate coil.
[0013] In sum, the advantages of the present process consist in the
possibility of endless rolling without welding of precursor strip,
endless rolling with homogeneous precursor strip characteristics
with respect to temperature and geometry, increased production in
the plant through higher possible rolling speeds which are no
longer limited by the threading-in processes in the coiler, and in
the creation of greater buffer capacity between the casting strand
and the finishing train.
[0014] The process can be applied in single-strand or two-strand
plants, wherein the coiling principle for the precursor strip can
be carried out with a mandrel in coiling furnaces or without a
mandrel in coil boxes, as they are called.
* * * * *