Note: Descriptions are shown in the official language in which they were submitted.
216~700
lN-l~K~EDIATE THI~KN~ AND MULTIPLE FURNA OE
PRO OE SS LINE WITH SLAR STORAGE AND SLAR SE~u _lN~
FIELD OF l~ lNV~ lON
This invention relates to the continuous casting
and rolling of slabs and, more particularly, to an
integrated intermediate thickness caster and a hot
reversing mill with flexibility in slab sourcing,
sequencing and storage with the ability to roll thin gauge
products.
R~G~OUND OF THE lNv~.llON
Since the advent of the continuous casting of
slabs in the steel industry, companies have been trying to
combine the hot strip mill with the continuous caster
through an inline arrangement so as to maximize production
capability and minimize the equipment and capital
investment required. The initial efforts in this regard
consisted of integrating continuous casters producing slabs
on the order of 6 to 10 inches (152.4 to 254 millimeters)
with existing continuous or semicontinuous hot strip mills.
These existing hot strip mills included a reheat furnace,
a roughing train (or a reversing rougher) and a six or
seven stand finishing mill with a capacity of 1.5 to 5
million tons (1.4 to 4.5 million metric tons) per year.
This arrangement is the present day design of large steel
company hot mills, and it is unlikely that new hot strip
mills of this design would ever be built due to the high
capital cost. The quest for low cost integrated caster hot
strip mills is not solved by current designs. Further,
such prior art integrated mills were extremely inflexible
as to product mix and thus current market requirements.
These difficulties gave rise to the development
of the so-called thin slab continuous hot strip mill which
typically produces 1,000,000 tons (907,185 metric tons) of
steel per year as standard products. These mills have been
integrated with thin slab casters on the order of two
inches (50.8 mm) or less. Such integrated thin slab
216S700
casters are enjoying increased popularity but are not
without serious drawbacks of their own. Significant
drawbacks include the quality and quantity limitations
associated with the thin slab casters. Specifically, the
trumpet-type mold necessary to provide the metal for the
thin slab can cause high frictional forces and stresses
along the surface of the thin wall slab which leads to poor
surface quality in the finished product. Further, the two-
inch (50.8 mm) strip casters are limited to a single
tundish life of approximately seven heats because of the
limited metal capacity of the mold.
Most importantly, the thin casters, by necessity,
have to cast at high speeds to prevent the metal from
freezing in the current ladle arrangements. This, in turn,
requires the tunnel furnace which is just downstream of the
slab caster to be extremely long, often on the order of 500
feet (152.4 meters), in order to accommodate the speed of
the slab and still be able to provide the heat input to a
thin slab (two inches)(50.8 mm) which loses heat at a very
high rate. Since the slab also leaves the furnace at a
high speed, one needs the multistand continuous hot strip
mill to accommodate the rapidly moving strip and roll it to
sheet and strip thicknesses. However, such a system is
still unbalanced at normal widths since the caster has a
capacity of about 800,000 tons (about 725,750 metric tons)
per year and the continuous mill has a capacity as great as
5 million tons (4.54 million metric tons) per year. The
capital cost of such a system then approaches that of the
earlier prior art systems which the system was intended to
replace.
In addition, the scale loss as a percentage of
slab thickness is substantial for the two inch (50.8 mm)
thin cast slab. Because of the extremely long furnace, one
must provide a long roller hearth which becomes very
216~70~
maintenance intensive because of the exposed rotating
rollers.
It has been suggested that light gauge hot band
on the order of 0.040 inch (1.016 mm) be rolled from these
two inch (50.8 mm) slabs. However, in the case of low
carbon steels, the thermal decay is too great on a
multistand continuous mill making it impossible to achieve
the necessary finishing temperatures; and in the case of
low alloy high-strength steels, it has been reported that
the two inch thick slab does not produce the reduction
required for high-strength low alloy steel which then
causes a coarse microstructure which must then be refined
through special temperature treatments which are greater
than for the cold charging of the same microalloyed steel
grade, "Optimisation of hot rolling schedule for direct
charging of thin slabs of Nb-V microalloyed steel", N.
Zentara and R. Kaspar, Materials Science and TechnoloqY,
May 1994.
The typical multistand hot strip mill, likewise,
requires a substantive amount of work in a short time which
must be provided for by larger horsepower rolling stands
which, in some cases, can exceed the energy capabilities of
a given area, particularly in the case of emerging
countries. Thin slab casters, likewise, are limited as to
product width because of the difficulty in using vertical
edgers on a two inch (50.8 mm) slab. Further problems
associated with the thin strip casters include the problems
associated with keeping the various inclusions formed
during steel-making away from the surface of the thin slab
where such inclusions can lead to surface defects if
exposed. Furthermore, existing systems are limited in
scale removal because thin slabs lose heat rapidly and are
thus adversely affected by the high-pressure water normally
used to break up the scale.
21~S700
..
In addition, this thin strip process can only
operate in a continuous manner, which means that a
breakdown anywhere in the process stops the entire line,
often causing scrapping of the entire product then being
processed.
The integration of a slab caster with any hot
rolling mill requires a synchronizing of the casting and
rolling of slabs. Without the ability to decouple the
casting and rolling of slabs in such an integrated system,
a breakdown anywhere in the process stops the entire line,
possibly resulting in the scrapping of the entire product
then being processed. The casting and rolling of slabs can
be effectively decoupled by providing the ability to
transfer a cast slab to a slab storage area. However, this
solution is inefficient. The slab is transferred to an
external slab storage area such that when the mill is
brought back on-line, a substantial amount of energy is
required to bring the slabs back to an appropriate rolling
temperature. Several other approaches have been attempted
to address this particular problem. These include
retaining or storing hot slabs in a heating furnace or in
a thermal insulating chamber. However, these solutions
have also had certain drawbacks, including the space
required and the capital expense involved.
It is an object of our invention to integrate an
intermediate thickness slab caster with a hot reversing
mill. It is a further object to adopt a system which
balances the rate of the caster to the rate of the rolling
mill and provides for decoupling of the caster from the
mill, as needed. It is also an object of our invention to
adopt a system using less thermal and electrical energy.
It is still a further object to adopt an automated system
with small capital investment, reasonable floor space
requirements, reasonably powered rolling equipment and low
operating costs. It is a further object to provide
~ `~ 2165700
flexibility in slab sourcing, sequencing and storage, and
to economically accommodate increased demand for light
gauge wide strip.
SUMMARY OF THE lNv~.LlON
Our invention provides for a versatile,
integrated caster and minimill capable of producing at
least 650,000 and preferably in excess of 1 million
finished tons (at least 589,670 and preferably in excess of
987,185 finished metric tons) a year with a divergent
product mix. Such a facility can produce product 24 to 120
inches (610 to 3,048 mm) wide and can routinely produce a
product of 800 PIW with 1,200 PIW being possible. This is
accomplished using a casting facility having a fixed and
adjustable width mold with a straight, rectangular cross
section without the trumpet-type mold. The caster has a
mold which contains enough liquid volume to provide
sufficient time to make flying tundish changes, thereby not
limiting the caster run to a single tundish life. Our
invention provides a slab approximately two to three times
as thick as the thin cast slab, thereby losing much less
heat and requiring a lesser input of BTU's of energy. Our
invention provides a slab having a lesser scale loss due to
reduced surface area per volume and permits the use of one
or two reheat or equalizing furnaces with minimal
maintenance required. Further, our invention provides a
caster which can operate at conventional caster speeds and
conventional descaling techniques. Our invention provides
for the selection of the optimum thickness cast slab to be
used in conjunction with a twin stand, tandem hot reversing
mill providing a balanced production capability. Our
invention has the ability to separate the casting from the
rolling if there is a delay in either end. Our invention
provides for hot slab storage if the delay is in the
rolling. Our invention provides for the easy removal of
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216~700
transitional slabs formed when molten metal chemistry
changes or width changes are made in the caster.
Furthermore, our invention provides for easily bringing
cold slabs into the processing line. Such slabs may be
outsourced (i.e., slabs not formed by the caster) and may
be thicker than those which may be cast by the caster.
This versatility will allow the processing line to be
operated at the respective capacity of the individual
components and allows for various portions of the line to
be independently operated. This outsourcing of slabs also
permits the product mix to include steel grades beyond the
capability of the steel-making facility which forms a part
of any given integrated process.
All of the above advantages are realized while
maintaining the advantages of a thin caster which include
low ferrostatic head, low weight of slab, straight molds,
shorter length molds, smaller required mold radii, low
cooling requirements, low burning costs or shear capacity
and simplified machine constructions.
Our invention provides an intermediate thickness
slab caster integrated with a hot strip and plate line
which includes at least one reheat or equalizing furnace
capable of receiving slabs directly from the caster, from
a slab collection and storage area positioned adjacent a
slab conveyor table exiting the continuous caster or from
another area. One embodiment of the present invention
includes a slab container capable of receiving slabs from
the caster. A feed and run back table is positioned at the
exit end of one of the reheat furnaces and inline with a
twin stand hot reversing mill having a coiler furnace
positioned on either side thereof. In one embodiment of
the present invention the feed and run back table is in
alignment with the coiler such that the reheat furnace may
be selectively bypassed. The mill can reduce a cast slab
to a thickness of about one inch (25.4 mm) or less in a
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minimum number of flat passes, about three or four flat
passes. The combination coil, coiled plate, sheet in coil
form or discrete plate finishing line extends inline and
downstream of the hot reversing mill and the coiler
furnaces. The finishing facilities may include a cooling
station, a downcoiler, a plate table, a shear, a cooling
bed crossover, a plate side and end shear and a piler.
To achieve the necessary balance between the hot
reversing mill and the caster, it is preferable to cast
slabs having a thickness of about 3 to about 6 inches
(about 76 to about 152 mm) and preferably between about 3.5
to about 5.5 inches (about 88.9 to about 139.7 mm). As
used herein, the term intermediate thickness is generally
intended to define such slabs, although in certain
specialty steels such as stainless steel intermediate
thickness slabs may extend up to about 8 inches (about
203 mm). The cast slabs are reduced to a thickness capable
of being coiled and normally about one inch (about 25.4 mm)
or less in four flat passes on the hot reversing mill
before starting the coiling of the intermediate product
between the coiler furnaces as it is further reduced to the
desired finished product thickness. In order to provide
the capability of making coiled plate, discrete plate and
sheet in coil form up to 1,000 PIW and higher, slab width
may vary from 24 to 120 inches (610 to 3,048 mm).
One processing line of the present invention
includes an intermediate thickness continuous strip caster
with an inline shear downstream of the caster for cutting
a cast strand into an intermediate thickness slab of the
desired length. A slab conveyor table is provided inline
with the shear and a slab loading and unloading mechanism
positioned adjacent the conveyor for supplying slabs
thereto. A slab collection and storage area is adjacent
the slab loading and unloading mechanism for receiving and
supplying slabs thereto. At least one reheat furnace is
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provided having an entry end inline with the slab conveyor
table for receiving slabs therefrom and supplying reheated
slabs to a feed and run back table positioned at the exit
end of the reheat furnace. A hot reversing mill is
provided inline with the feed and run back table for
reducing a slab on the feed and run back table to an
intermediate product having a thickness sufficient for
coiling in a number of flat passes. Two spaced coiler
furnaces are positioned inline with the feed and run back
table, with one located upstream of the hot reversing mill
and the other located downstream thereof. The coiler
furnaces are capable of receiving and paying out the
intermediate product as it is passed between the coiler
furnaces and through the hot reversing mill so as to be
reduced to an end product. A finishing line is provided
downstream and inline with the coiler furnaces and the hot
reversing mill.
In the above-described apparatus, the hot
reversing mill includes a pair of four-high rolling mill
stands adapted to be operated in tandem with an adjustable
vertical edger positioned between the pair of rolling mill
stands. Additionally, the slab loading and unloading means
includes a first slab transfer device adjacent the slab
conveyor table and operable transverse to the slab conveyor
table, wherein the feed and run back table is positioned
adjacent an end of the first slab transfer device. A
second slab transfer device is adjacent the feed and run
back table, wherein the slab collection and storage area is
adapted to receive slabs from and supply slabs to the
second slab transfer device. Additionally, this embodiment
of the present invention may include a second reheat
furnace having an entry end inline with a feed and run back
table and an exit end inline with the slab conveyor table.
The method of operation of processing coil plate,
sheet in coil form or discrete plate according to the
2165700
present invention includes providing an intermediate
thickness continuous caster and inline shear for casting an
intermediate thickness strand and shearing the strand into
a slab of predetermined length. Additionally, a slab
loading and unloading device adjacent the slab collection
and storage area for moving slabs between a position inline
with the intermediate thickness caster and the slab
collection and storage area is provided.
As discussed above, one embodiment of the present
invention may include a slab container which includes a
vertically movable carriage adapted to engage a lowermost
slab and a stack of the slabs, wherein the slabs in the
stack are directly contacting each other. Insulation may
be provided to surround at least the sides and top of the
stack. In one embodiment of the invention, the carriage
may be mounted on a track within an insulated slab holding
pit with a cover adapted to enclose the slab holding pit.
In a second embodiment, the carriage may include one or two
pairs of slab engaging arms adapted to engage and support
a lowermost slab in the stack of slabs. The slab engaging
arms are preferably movable to accommodate varying slab
widths and include insulating side and top members attached
to each slab engaging arm. The top members of the
insulation on respective slab engaging arms are configured
to overlap each other, allowing for movement of the slab
engaging arms to accommodate the varying widths of the
slabs.
A slab originating from either the intermediate
thickness caster, the slab container (if provided) or the
slab collection and storage area is fed to an inline
heating furnace. The slab to be reduced is extracted from
the inline heating furnace onto a continuous processing
line which includes a hot reversing mill having a coiler
furnace on each of the upstream and downstream sides
thereof. The slab to be worked is passed back and forth
216~00
through the reversing mill to form an intermediate product
of a thickness capable of being coiled. The intermediate
product is coiled in one of the coiler furnaces. The
coiled intermediate product is passed back and forth
through the mill to reduce the coiled intermediate product
to an end product of desired thickness, the intermediate
product being collected in and fed out of each of the
coiler furnaces on each pass through the hot reversing
mill. The end product may be finished into one of either
coiled plate, discrete plate or sheet in coil form.
The method according to the present invention
also provides that some of the coil slabs may bypass the
heating furnace if the temperature of the slab is
sufficient for rolling; additionally, some of the slabs
supplied to the heating furnace may be outsourced (i.e.,
slabs which were not cast in the intermediate thickness
caster). These outsourced slabs may have a thickness
greater than slabs cast by the intermediate thickness
caster and/or a chemistry different from that which can be
produced on the melting/refining furnace(s) associated with
the caster. The hot reversing mills of the present
invention include a pair of rolling mill stands adapted for
operation in tandem further including an adjustable
vertical edger positioned between the pair of rolling mill
stands. The method of the present invention may include a
second heating furnace adjacent the inline heating furnace
to provide for a wide versatility in slab sourcing,
sequencing and processing, as will be described in detail
hereln .
BRIEF DESCRIPTION OF 1~ DRAWINGS
Figs. lA and lB are schematics illustrating an
intermediate thickness strip caster and inline hot
reversing mill and coiler furnace arrangement according to
a first embodiment of the present invention;
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~`` 21~570~
_
Fig. 2 is a schematic illustrating an
intermediate thickness strip caster and inline hot
reversing mill and coiler furnace arrangement with multiple
reheat and equalizing furnaces according to a second
5 embodiment of the present invention;
Figs. 3A and 3B are schematic illustrations of a
third embodiment for the intermediate thickness strip
caster and inline hot reversing mill and coiler furnace
arrangement according to the present invention;
Fig. 4 is a sectional view of one embodiment of
a slab storage container shown schematically in Figs. 3A
and 3 B;
Fig. 5 is a side view of another embodiment of a
slab storage container shown schematically in Figs. 3A and
15 3B; and
Fig. 6 is a front view of the slab storage
container shown in Fig. 5.
DESCRIPTION OF l~ PR~KK~V EMBODIMENT
The intermediate thickness slab caster and inline
20 hot strip and plate line of a first embodiment of the
present invention is illustrated in Fig. lA. This
embodiment is well suited for slab sequencing as will be
discussed hereinafter. One or more electric melting
furnaces 26 provide the molten metal at the entry end of
25 our combination caster and strip and plate line 25. The
molten metal is fed into a ladle furnace 28 prior to being
fed into the caster 30. The caster 30 feeds into a mold
(curved or straight) 32 of rectangular cross section.
A torch cutoff (or shear) 34 is positioned at the
30 exit end of the mold 32 to cut the strand of now solidified
metal into an intermediate thickness slab, about 3.0 to 6
inches (about 76 to about 152 mm) thick, of the d~sired
length which also has a width of 24 to 120 inches (610 to
3048 mm).
.
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_ 21657~0
The slab then feeds on a feed and run back table
52 to a slab takeoff area where it may be removed from the
feed and run back table 52 by a movable slab transfer table
35 operating transverse to the feed and run back table 52.
5 The slabs are moved by the slab transfer table 35 to a
table conveyor 36 to be charged into a furnace 42 or
removed from the inline processing and stored in a slab
collection and storage area 40 which normally will house
slab conditioning facilities of one type or another. The
provision of the easily accessible slab collection and
storage area allows for a decoupling of the caster and the
downstream processing. For example, if the mill goes off-
line during a casting, the r~m~;n;ng casts may be forwarded
to the slab collection and storage area. Additionally, if
15 the caster were off-line, then the downstream processing
can be continued with outsourced slabs. The slab
collection and storage area 40 allows individual slabs to
be collected for individual surface processing to address
defects in individual slabs. The preferred furnace is of
20 the walking beam type although a walking hearth furnace
could also be utilized in certain applications. Full-size
slabs 44 and discrete length slabs 46 for certain plate
products are shown within walking beam furnace 42. Slabs
38, which are located in the slab collection and storage
25 area 40, may also be fed into the furnace 42 by means of
slab pushers 48 or charging arm devices located for
indirect charging of walking beam furnace 42 with slabs 38.
It is also possible to charge slabs from other slab yards
or storage areas. Where slabs are introduced from the slab
30 collection and storage area 40 or from the off-line
locations, the furnace 42 must have the capacity to add
Btu's to bring the slabs up to rolling temperatures.
Because the intermediate thickness slabs retain
heat to a much greater extent than the thin slabs,
35 temperature equalization is all that is required in many
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216S700
modes of operation. Additionally, for certain cast slabs,
the internal temperature throughout the slab as it is
received on the feed and run back table 52 may be
sufficient for rolling directly. In this situation, the
5 slab may be fed directly to downstream processing,
bypassing the furnace 42. It is also anticipated that a
second furnace may be positioned upstream of the first
furnace 42 to increase the flexibility and the control of
the current system.
The various slabs are fed through the furnace 42
in a conventional manner and are removed by slab extractors
50 and placed on the feed and run back table 52. Descaler
53 and/or a vertical edger 54 can be utilized on the
intermediate thickness slabs. A vertical edger normally
15 could not be used with a slab of only 2 inches (50.8 mm) or
less.
Downstream of feed and run back table 52 and
vertical edger 54 is a single stand hot reversing mill 56
having an upstream and a downstream coiler furnace 58 and
20 60, respectively. Run out table 61 and cooling station 62
are downstream of coiler furnace 60. Downstream of cooling
station 62 is a coiler 66 operated in conjunction with a
coil car 67 followed by a plate table 64 operated in
conjunction with a shear 68. The final product is either
25 coiled on coiler 66 and removed by coil car 67 as sheet in
strip or coil plate form or is sheared into plate form for
further processing inline. A plate product is transferred
by transfer table 70 which includes a cooling bed onto a
final processing line 71. The final processing line 71
30 includes a plate side shear 72, plate end shear 74 and
plate piler 76. Of course, the plate product facility is
omitted where only coil or coil and sheet product are
desired.
The advantages of the subject invention come
35 about as the result of the operating parameters employed
- 2165700
\ -
and the sequencing flexibility available with the current
design. The cast strand should have an intermediate
thickness, generally between about 3.0 inches to about 6
inches (about 76 to about 152 mm) , preferably between 3.5
inches to 5.5 inches (about 88.9 to about 139.7 mm). The
width can generally vary between 24 inches and 100 inches
(610 mm and 2,540 mm) to produce a product up to 1,000 PIW
and higher.
The slab is flat passed back and forth through
hot reversing mill 56 in a minimum number of flat passes
achieving a slab thickness of about 1 inch (25.4 mm) or
less. The intermediate product is then coiled in the
appropriate coiler furnace, which in the case of three flat
passes would be downstream coiler furnace 60. Thereafter,
the intermediate product is passed back and forth through
hot reversing mill 56 and between the coiler furnaces to
achieve the desired thickness for the sheet in coil form,
the coil plate or the plate product. The number of passes
to achieve the final product thickness may vary but
normally may be done in nine passes which include the
initial flat passes. On the final pass, which normally
originates from upstream coiler furnace 58, the strip of
the desired thickness is rolled in the hot reversing mill
and continues through the cooling station 62 where it is
appropriately cooled for coiling on a coiler 66 or for
entry onto a plate table 64. If the product is to be sheet
or plate in coil form, it is coiled on coiler 66 and
removed by coil car 67. If it is to go directly into plate
form, it enters plate table 64 where it is sheared by shear
68 to the appropriate length. The plate thereafter enters
a transfer table 70 which acts as a cooling bed so that the
plate may be finished on final processing line 71 which
includes descaler 73, side shear 72, end shear 74 and piler
76.
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2165700
The intermediate thickness continuous caster and
hot strip and plate line provide many of the advantages of
the thin strip caster without the disadvantages. The basic
design of the facility can be predicated on rolling 150
5 tons (136 metric tons) per hour on the rolling mill. The
market demand will obviously dictate the product mix, but
for purposes of calculating the required caster speeds to
achieve 150 tons (136 metric tons) per hour of rolling, one
can assume the bulk of the product mix will be between 36
inches (914 mm) and 72 inches (1829 mm). A 72 inch
(1829 mm) slab rolled at 150 tons (136 metric tons) per
hour would require a casting speed of 61 inches (1549 mm)
per minute. At 60 inches (1524 mm) of width, the casting
speed increases to 73.2 inches (1859 mm) per minute; at 48
inches (1219 mm), the casting speed increases to 91.5
inches (2324 mm) per minute; and at 36 inches (914 mm) of
width, the casting speed increases to 122 inches (3099 mm)
per minute. All of these speeds are within acceptable
casting speeds.
The annual design tonnage can be based on 50
weeks of operation per year at 8 hours a turn and 15 turns
per week for 6,000 hours per year of available operating
time assuming that 75~ of the available operating time is
utilized and assuming a 96~ yield through the operating
25 facility, the annual design tonnage will be approximately
650,000 finished tons (589,670 metric tons).
The intermediate thickness slab caster and inline
hot strip and plate line according to a modified version of
the first embodiment of the present invention is
30 illustrated in Fig. lB. The combination caster and strip
and plate line 25 iS identical to the line 25 described in
connection with Fig. lA except that a twin stand hot
reversing mill 56 ' replaces the single stand hot reversing
mill. The provision of the twin stand increases the
35 rolling capacity of the mill. Additionally, the twin stand
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mill 56 ' allows for processing of outsourced slabs which
are thicker than the intermediate thickness slabs which
could be produced by the caster 30. With the twin stand
mill 56', four flat reducing passes on the feed and run
5 back table 52 (with two passes occurring with each passage
of the slab along the feed and run back table 52) are
normally required to arrive at a thickness capable of being
coiled.
An intermediate thickness slab caster and inline
hot strip and plate line including multiple furnaces and/or
a multiple stand hot reversing mill according to a second
embodiment of the present invention is illustrated in
Fig. 2. The process line in Fig. 2 is similar in many
respects to the line illustrated in the embodiment shown in
15 Fig. 1. One or more electrical melting furnaces 126 will
provide the molten metal at the entry end of the
combination intermediate thickness caster and strip and
plate processing line. The molten metal is fed into a
ladle furnace 128 prior to being fed into the intermediate
20 thickness caster 130. The caster 130 feeds into a curved
or straight mold 132 of rectangular cross section. A torch
cutoff or shear 134 is positioned at the exit end of the
mold 132 to cut the strand of solidified metal into an
intermediate thickness slab of desired length which may
25 also have a width of 24 to 120 inches (610 to 3,048 mm).
The intermediate thickness slab then feeds onto a slab
conveyor table 136. A hot scarfer 137 may be positioned
above the slab conveyor table 136 for processing the
surface of the slabs. The slab may be removed from the
30 inline processing and stored in a slab collection and
storage area 140 or it may be directly charged from the
slab conveyor table 136 into an entry side of an equalizing
or reheat furnace 142. The preferred furnace 142 is of a
walking beam type, although a roller hearth furnace could
35 be utilized in certain applications. The various slabs are
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- `- 2165~00
fed through the furnace 142 and removed in a conventional
manner and placed on a feed and run back table 152
positioned at the exit of the furnace 142. The feed and
run back table 152 is inline with the caster 130 in the
processing sense but is not physically aligned with the
caster as in the first embodiment.
When slabs are transferred to the slab collection
and storage area 140, they can be removed from slab
conveyor table 136 by a slab transfer table 138 operating
transverse to the processing line. The slab transfer table
138 will transfer a slab from the slab conveyor table 136
to the feed and run back table 152. A second slab transfer
table 144 is positioned adjacent the feed and run back
table 152 to transfer slabs from the feed and run back
table 152 to the slab collection and storage area 140. An
alternative arrangement would combine the first and second
slab transfer tables 138 and 144 into a single transfer
table extending from the slab conveyor table to the slab
collection and storage area 140 with the feed and run back
table 152 extending from and receiving slabs from an
intermediate portion of the combined slab transfer table.
A furnace 146 is positioned between the slab
conveyor table 136 and the feed and run back table 152 and
positioned adjacent the furnace 142. The furnace 146 may
have an entrance side on the feed and run back table 152
and an exit end on the slab conveyor table 136. The slab
storage area additionally includes a slab conditioning
section 148 wherein further surface processing on the slabs
can be performed, as needed.
The disclosed dual furnace and slab loading and
unloading arrangement provides for great versatility in
slab sourcing and processing. As discussed above, a slab
cast from the intermediate thickness caster 130 can be fed
directly through furnace 142 onto the feed and run back
table 152 and into the processing line. Because the
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- ~ 216S~O~
intermediate thickness slabs retain heat to a much greater
extent than the thin slabs, the temperature equalization is
generally all that will be required in many modes of
operation.
The present arrangement additionally provides for
transferring a slab from a position inline on the slab
conveyor table 136 to the slab collection and storage area
140 through slab transfer tables 138 and 144. Such storage
may be required to allow continuous casting to continue
when a breakdown downstream in the processing line has
occurred or, alternatively, allows for removing individual
slabs for further processing in the slab conditioning
section 148 such as due to any undesirable surface defects.
The present arrangement provides for great versatility in
15 bringing slabs from the slab collection and storage area
140 back in the processing line.
In short delays, the slab may be passed directly
onto the feed and run back table 152 by the slab transfer
table 144 for subsequent processing. A second alternative
20 would be to transfer a slab onto the slab conveyor table
136 through both slab transfer tables 138 and 144. The
slab can then continue down through furnace 142 and to the
feed and run back table 152 for processing. Where cold
slabs are being re-introduced into the processing line, the
25 present arrangement allows for the slab to be transferred
to the slab conveyor table 136 through the reheat furnace
146 which will have a capacity to add BTU~s to bring the
slab up to the appropriate temperature for subsequent
processing. The present arrangement additionally provides
30 for introducing outsourced slabs into the processing line.
Outsourced slabs refer to slabs which were not cast on the
intermediate thickness caster 130. Such outsourced slabs
may have any thickness, including a thickness greater than
that cast on the intermediate thickness caster 130 and/or
35 a chemistry different than what can be produced or achieved
` 211~00
in electric melting furnaces 126 and ladle furnace 128.
The additional ability of incorporating outsourced slabs
into the processing line provides additional options for a
more complete matching of the speed of the intermediate
5 thickness caster 130 and the supply of outsourced slabs to
the downstream processing.
An alternative embodiment of the present
invention is contemplated wherein furnace 146 has an
entrance side on the slab conveyor table 136 and an exit
side on the feed and run back table 152. In such an
arrangement, the slabs from the slab collection and storage
area 140 would generally be supplied to the slab conveyor
table 136 and then through an appropriate one of the
furnaces 142 or 146. In this alternative arrangement, both
15 furnaces would generally be operated in the same manner.
In the embodiment disclosed in Fig. 2, furnace 146 can be
utilized and operated as a reheat furnace whereas furnace
142 can be generally operated as an equalizing-type
furnace.
The present arrangement additionally provides for
directly transferring an appropriate slab from the slab
conveyor table 136 to the feed and run back table 152 for
subsequent processing without going through either of the
furnaces 142 or 146 as in the first embodiment. Such
25 procedure would only be possible if the cast slab already
contains an appropriate rolling temperature throughout.
This alternative further illustrates the inherent
flexibility of the present design.
The slabs positioned on the feed and run back
30 table 152 for subsequent working are passed through a
conventional descaler 153. As discussed above, such a
descaler process could be detrimental to 2 inch thin cast
slabs.
Downstream of feed and run back table 152 and
35 aligned therewith is a hot reversing mill which includes a
-- 19 --
216570~
pair of four-high rolling mill stands 156 configured to
operate in tandem. Positioned between the pair of rolling
mill stands 156 is an adjustable vertical edger 154.
Vertical edger 154 is intended to be used conventionally or
to taper the leading and trailing ends, respectively, of
the slab on the first pass through the mill so as to
compensate for the flaring out of the extreme ends which
occurs during subsequent rolling. Such tapering can be
controlled by the AGC, and the vertical edger can be
passively driven by the twin stands of the mill. The
effectiveness of the tapered ends can be monitored by a
width gauge at the exit end of the downstream hot reversing
stand wherein a fingerprint of the width is taken and
adjustments are made through a feedback loop to the
vertical edger, where necessary.
Upstream and downstream coiler furnaces 158 and
160, respectively, are positioned on either side of the
pair of rolling mill stands 156 of the hot reversing mill.
A run out table 161 extends downstream from the coiler
furnace 160. A cooling station 162, such as l~m-n~r flow
cooling, is downstream of the downstream coiler furnace 160
and extends along the run out table 161. Downstream of the
cooling station 162 is an upcoiler 166 which can be
operated in conjunction with a coil car 167. A subsequent
finishing line may be provided substantially the same as
described above in Fig. 1 which includes shear 68, transfer
table 70, final processing line 71, plate side shear 72,
plate end shear 74 and plate piler 76.
The provision of tandem operated twin reversing
stands 156 in the hot reversing mill of the present
invention includes increased processing tonnages as well as
the ability to achieve lighter gauges such as 0.040 inch,
which are of increasing importance in many industries such
as the building industry where light gauge hot mill product
is formed into studs and the like to replace lumber. The
- 20 -
I 216~700
additional expense of incorporating a twin stand reversing
mill rather than a single stand reversing mill is justified
by the increased productivity and versatility and the
incorporation of outsourced slabs from the slab collection
and storage area 140, as discussed above. As noted, such
outsourced slabs may have a thickness greater than those
cast in the caster 130 and can provide for an even greater
variety of product mix. The following Examples illustrate
such a product mix.
- 21 -
21G~ 70 D
EXAMPLE I
A 48.99 inch (1244 mm) wide x 0.040 inch (1.016
mm) thick sheet in coil form is produced from a 5 1/2 inch
(139.7 mm) cast slab in accordance with the following
rolling schedule:
- 22 -
216S700
~ ~ o a~ ~D r
cn o o CD d~ ~ r a~
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~ Z ~Eq r ~ n r~
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N ~ -- H
: p
C ~ ~z ~,r3~ ......................
s:u~Z
rt'
rr, ~
, ~ o o ~ ~ ~ ~ In ~ r
-
~ o ~n o u~
- - 2165700
~ a
o
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O ~ ~) ~ ~ o o a~ 0 t ~D O
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"~ ~H ~ ~ I`') O O D ~ O O In ~ IJ~ ~
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o~ ~ ~ ~ ~ o o t~ o 1-') ~
Z ~ N t~ ~1 ~1 ~J O O O ~51 Crl
I
r~ o ~ o ~ ~ r r~
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o ~ ~ r CD o a~ r ~ In
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o ~ N o~ un m ~ N r a~ ~
r a~ r r N N IS') r r ~l O
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~ ~ ~ ~I N N ~1 ~I N N ~ ~1 N
N U
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Ln o In o
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.. 216~00
' 8 ~ ~ ' ~ ~ ~ X ~ ~ U u ~
. ~ ~ ~ ` ~ ~`~ ~ ~c~ X _ ~ a a S - a a
~3 8 ~ o ~ ~ ~ ~ x ~ ~ o o r ~ .
g ~ ~ O ~ O ~ ~ ~n o r
O o ~ ~ o
888~8888888 Ln -
o~ ~ ~ ~ a a ;~; c ;~ ~ u
o ~ ~ a~ D r~ t 4
a~ c
o ~ ~ C
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_. u~ a~ a~ o cr~ a u~ L , O
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'C-C C
g ~ U~~ U~ O ~ O
C g u l~ ~ o u~ a~ ~ ~ ~ - E~ " ,~
* ~ a~ u-~ ~ ~ E
'I ~43 ~ j C ~ o ~ ~ ~ OO 1~ u~ u~~ Oo a) E~ E~ O
~ I r ~ ~ ~ Q O O C ~ ~ t` on 1~
_ CO ~# ~ g ~ C`l ;~ ~0 0 U~ U~ I` Cr~ O
r~ : O ~i ~ ~ ~ ~ ~ ~ ~ ~ ~ -
u~ 8 ~ U~ u~ ~ æ ~o ~
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- ~- 216570Q
Example I illustrates one of a wide variety of
product types which can be rolled with the present system.
As illustrated in this Example, the present mill can
economically hot roll down to 0.040 inch (1.0 mm) thick.
The provision of the twin stands allows for accurately
rolling down to these light gauges for which there is an
increased market demand.
216~ ~0~
EXAMPLE II
A 55 inch (1397 mm) wide x 0.060 inch (1.52 mm)
thick sheet in coiled form is produced from a 5 1/2 inch
(139.7 mm) cast slab in accordance with the following
rolling schedule:
- 27 -
- 2165700
. _
3 i o a~
H :,O 1~ ~ r ~ t~ ~ x u7 CD x
V~ ~ ~ r ~o o 0 ~ ~
. H ~~1 ~ ~ O ~ ~ ~ t` t`
O--~ li E~ tQ~1 ~1 ~ N ~
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o ~
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o z . u~ 0 ~ r o
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p O
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o ~ r t~
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H ~ H ~ ~ . . . . . . . .
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0 ~ ~ ~ ~ U~ ~D r 0 a~ o
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2165700
3 ~ N a~ ~ ~1 ~ 0~ ~ ~ O a) r
H ~ U ~ ~ o o ~ ~ o ~ r o~ a~
p,~ . ...........
N E~ ~ o ~1 ~ ~7 ~ 0 Il~
H V ~ o o r t~ o ~D o t~
O X ~ ~ ~ ~ N ~~ ~ O o
o -
O ~1 ~ ~ ~ O~ In ~ ~D ~D
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N N ~1 ~1 ~1 ~1 0 0~ CD r
o
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o : : : ~ o ~ t~ a~ ~ o ~ ~ c~ ~o r
n ~ " ~ O x ~ ~P r D N r oo ~ 0 ~j
Z ~ t ~ N ~1 ~1 ~1 0 0 0 ~ a~ ~ r~
E' ~ o a~ a) o o In ~ ~ o ~ d~ t~
~ ~ ~ ~ In o ~ ~ ~ r U~
HU O ~ O O O ~1 D O
o x o o o u) ~ ~ o o
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10 C~ D CO ~ N --1 0 0
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216~70~
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~1 a~
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~: n~ o~
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o r ~D o ~ m ~ s
O O ~ 0 ~ r ~ a~ m ~D 0 ~ ~
"~ * o ~ n 0 a~ In ~ r t~ E ^ ^
X ~ ~ ~: o r r ~ r ~ ~ ~ o E ~ o cJ
r ~ h _ ~ o ~ ~~ o o o o o o ~ ` ~ ~ ~` '
U~ r t~ r ~ O
~ : O ~ 0 r 0 r o r ,~
z E~ o r a~ ~ ~ ~ 0 ~ ~ ~ ~
~ O ~ ~ ~ r In ~ ~ ~ o
E~ H ~ r ~ ~I ~ ~I ~I O ~ o o a~
o o o o
o In ~ ~ 0 0 0 U~
cn ~ o r
H ~ O ~) ~ IS~ r
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~; O ~ ~ o ~1 ~ 0 ~ ~~ #
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o o ~ In o D O ~ In o ~1 -
U~ u~ ~ ~ ~ o ~ ~ ~ dl ~ ~ ~ ~ ~ ~ r~
~ ~ O O O O O O O O ~ ~D O a) ~ # r~o - o
o 0 o o o u~ r 0 ~ o o
c~ o ~ r o u~ r ~ ~ a~ r ~ 1~ ro a~ ~ r
~t ~ ~ ~ z ~ D 0 ~ ~ ~1 0 0 0 '-) U ~
H ~ a
ro ~ r -
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o ~ o ~ ~ ~ ~ u~ .D r 0 ~ c c c r~
u7 o ~ o In
216~70~
`
Example II, like Example I, illustrates the
versatility of the present system in hot rolling thin
gauges. These hot rolled narrow gauge products, such as
about 0.040 inch (1.0 mm) and about 0.060 inch (1.5 mm)
thick, are able to be utilized as final end products in
situations in which the final end product is generally not
exposed and does not require any surface finishing. Metal
construction studs, for example 0.040 inch (1.0 mm)
galvanized studs, represent one final end product that can
be hot rolled by the present invention. This is a distinct
advantage over the known prior art which would generally
hot roll somewhere above 0.080 inch (2.0 mm) thick then
pickle and finish the product on a cold mill with a
subsequent anneal and temper rolling.
- 31 -
2l6s70a
` -
EXAMPLE III
A 62 inch (1574.8 mm) wide x 0.090 inch (2.3 mm)
thick sheet in coil form is produced from a 10 inch (254
mm) outsourced slab in accordance to the following
schedule:
- 32 -
21~S700
H
E ~ ~ ~1 0 0 a~ ~ r ~ o ,l o ~
o U~ ' ~ O ~ ~ ~ ~ 0 0 ~p ~ ~ ~
O ~ ~
o ~
~J~ o In ~ D O ~1 0 U~ ~1 ~ O ~O d'
o :V ~---
o ~ ~ o 0 o ~ D 0 ~ r
O W ~1 ~1 ~1 ~ ~ ~ 0 ~ ~ In I
~D 0 a~
~1 N O O ~ 0 0 ~ o N
N ~) ~ r o Ln ~ o ~ N 0 r
H H N ~ r H ~D N r N
N i I ~ ~I H N N ~')
y o : ~ O N N N N O a~ ~) ~) 0 0 ~ H ~) ~1
Cio ~ O ~) ~ ~ ~) N 1~ ~ N a ~ O ~ 0
' O ~ ~ o r r r r ~D ~r N (J~ r ~ ~ ~ ~ ,i
o 1`~ 1~ (~) r~) u~ N In 0 ~1 IS) ~ N
0 0 0 0 0 N a~ O ~ H
E ~ ~ ~ D N ~ ') ~i ~1 0 0 1 ~,~
`1 N ~1 ~I L
O O O O O O O O O N ~D ~D ~ r ~
o ~ u~ In In r ~ ~ ~ r ~ r ~ N ~I C
5:~ O ~ P N O r ~ N ~i O O O O 'J
H o
o m o ~ r N N H H N O O O O O
N : ~ r r o m o ~o o ~ o ~ o u~
t ~ ~1 H N N ~ ~ ~ ~ ~ ~ ~ N N ~1
U~ O O O O O N 0 0 ~
Z ~ o r ~ ~1 0 N ~ ~ ~O O r~) ~ ~ O ~D
O U~ O ~ D ~ ~ ~ r In o 0 ~ a~ 0
U ~ 0 ~ oD r ~r~ 0N ~ D ~ ~ N N
N N H ~I H
O 0 H u~ O
o o o o o o o o o r N ~D N In O
0 U ~ O m o u~ o ~ r N ~O 0 Ul t` t~ O
N ' ~ r ~ ll ~1 ~ N a~ 0 ~1 ~ N H H H 0
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13 ~I N N H ~I N N ~1 ~I N N H ~ N
~q
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i !C) O H N r~) d', Il U~ r 0 a~ o H N 0
L~ O U~ O
H H N
-~ 216~i70~
3 ~ ~ m CD CD ~ r m ,~ o
~1~ ~ ~ ~ 11'1 0 ~ 0 ~D 1~ U) 111 O ~ 1'7 ~`1 ~1 0
~ ~ ~ O OD ~ ~ O ~ O ~ ~
o,~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~1 ,~ ~ ~1 ~1 o o o
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O O ~:
o O ~ ~ ~ ~1 U~ D In O O
o ~ ~ r t~ In ~ ~ 0 t~
a) ~-
NNNNN~OOO~
~NNNNNNNNNN~
O
~ N ~ ~ r ~ ~ ~ N~ r~ ~ ~ ~ ~
~ ~ N~ON~O~
- ~ -N~N~N r~ o ~ ~ o o
~ V ~ ~ 10 0 ~O ~D ~ ~ ~1 CD d~ r~
~ o ~Z~ NNNNNNN~OOO
o a) o ~ ~ t~ ~ o ~ ~ ~ r
o ~ ~ o o ~ r CD ~ a~ o ~ ~1
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NN~N~NN~N
N~ ~.:
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o
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n o ~n o
H HN
- - 216S70~
N
-- T O ~ I r ~ ~ 0 o ~ In ~D ~
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o ~ o ~D ~D r r r ~ o N -1 N ~r '7 In C~
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O
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o~ O 0 ~D 0 ~ U) r r~ D o ~ r N r 0
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d1 I r~ O 0 N ~1 0 0 N ~1 ~ D 0 N ~1 ~ O
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O 0 ~ t~ 0 ~ 0 ~ ~ IY7 t`') N N N ~I J
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- `~ 216570~
o ~ a) a~ ~ N O O D O ~ CD ~ r
m o o ~r ~ o t~ ~ o ,~
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N :~1 ~ O ~D ~1 I) ~ ~D ~1 D ~ ~ ~ r t~ 0 ~ ~ o~ r O
:1~ 3 3 ~D ~ In ~1 0 ~1 In ~ O ~) O ~ ~ O E E ~1 r
'~ ~0~ ~ ~, ~ r~ ~o ~ ~ ~ V~ ~ ~ ,~ 0 r:~ ~ ~ r r t`
. ~ ~ ~1 ~1 o o ~1 0 ~ ~
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o r a~ 0 0 o 0 In 0 0 0 . O O O O O
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r~ ~ ~ ~ N a~ ~Sl O ~ 0 r ~ o o~ ~ ~ o u~ 0
H ~
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O O O O O ~ 0 0 ~ O ~ ~`7 ~ O ~
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o
P: cn o o o o o o o o o r ~ ~ ~ u~ O ~q L) ~15, L 1l
O If ~ O m O ~) r~ N ~D 0 1~ t` 0 O CS~
~, O ~J7 ~ ~D ~ a~ 0 ,~ ~ ~ ~ ,1 ~1 ~1 0 ~1 a u ,~ ~ s
0 ~: ~, . . . . . . . . . . . . . . . . ,~ r~ a ~ ,1 a ~
N -- ~. Z ~ o 0 ~ U) ~ N ,~
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cn ~
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s m
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In O U~ O In o
216~700
Example III illustrates the flexibility of the
present system which can receive outsourced slabs for
further processing. Such outsourced slabs may be, as here,
slabs which are too thick to be cast in the intermediate
thickness caster or slabs which have a specialized
composition limiting where they may be produced or simply
additional slabs to supplement the caster product. The
rolling of outsourced slabs and the ability to store cast
slabs allows the casting and rolling to be decoupled and
operated independently of each other.
2165700
EXAMPLE IV
A 48 inch (1219.2mm) wide x 0.125 inch (3.175mm)
thick sheet of high carbon steel (0.51-0.95 carbon) in coil
form is produced from a 5 ~ inch (139.7mm) thick cast slab
in accordance to the following rolling schedule:
2165?0 D
~ W O ~D CD ~ ~ In o CD ~1 0 0
~ c~ o r o~ n o ~ ~ r ~
F C IY ' - - - - - - - - -
e ,~ O O
H E~ ~1 ~ ~ 0 a~
~D ~ U~ ~ ~ O ~ ~D O O X
X ~1 ~ ~ ~ ~o ~
~E~
: V ~ ~ ~D 0 ~ In ~ ~1 a~
F ~ m r ~~ ~ ~ o o o u~
S ;
o~ :
o o~ o a~ o In t~
O
u~ o ul ~ o ~n o ~
o t~ ~ ~ 0 0 r~ q
o a~ D O Ln ~ ~ O O '~
ê ~ L ~ ro N ~ ~ U
~j e ~ O ~ n O ~n u. O m ~ U
O ~D ~ r ~ o ~D ~ ~
o In ~ a~ O O O
H ~ ~ ~ . . . . . . . .
O ~ O U~ O r~ o
~i ~ O rl ~ o u~
H
~ o a~ ~o o ~ ~ o ~ a~
E~ ~: o ~ o ~/ ~ ~ a~ ~ ~ ~ r
-
~ o o o o o o o o o o o
o ~ o o ~ o o In ~ ~ u
O 1~) ~`1 If) X ~ ~ 0
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216~700
o a~ r
...........
...........
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.
o o a~ o ~1 o
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EXAMPLE V
A 60 inch (1524mm) wide x 0.100 inch (2.54mm)
thick sheet in coil form is produced from a 5 inch (127mm)
cast slab of low carbon steel according to the following
rolling schedule:
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`- 21B~700
Examples IV and V show the range of grades
producible on the present invention providing the broad
product mix needed for a competitive mill.
The intermediate thickness slab caster and inline
5 hot strip and plate line of a third embodiment of the
present invention is illustrated in Figs. 3A and 3B. The
third embodiment is similar to the first two embodiments
including electric melting furnaces 226 provided at the
entry end of the strip and plate line 225, ladle furnace
10 228, caster 230, mold 232 and cutoff 234 positioned at the
exit end of the mold 232 to cut the strand of now
solidified metal into a 3.5 to 6 inch thick slab
(intermediate thickness) of the desired length which also
has a width of 24 to 120 inches.
The slab then feeds on a table conveyor 236 to a
slab takeoff area where it is directly charged into a
furnace 242 or is stored in slab storage container 280 or
alternatively is removed from the inline processing and
stored in a slab collection area 240. If the cast slab is
20 needed to be stored prior to rolling, such as due to
maintenance on the rolling mill, it is preferred that the
slabs be stored in the slab storage container 280. The
slab collection area 240 will generally be utilized where
additional processing of a slab is required, such as
25 surfacing of the slab by hand scarfing. Full-size slabs 244
and discrete length slabs 246 for certain plate products
are shown within walking beam furnace 242. Slabs 238 which
are located in the slab collection area 240 may also be fed
into the furnace 242 by means of slab pushers 248 or
30 charging arm devices located for indirect charging of
walking beam furnace 242 with slabs 238. It is also
possible to charge slabs i.nto furnace 242 from the slab
storage container 280 which feed onto the table conveyor
236. AS discussed above, where slabs are introduced from
35 off-line locations, the furnace must have the capacity to
- 49 -
216~700
add Btu's to bring the slabs up to rolling temperatures.
The slab storage container 280 will minimize the need for
such off-line slab loading.
The various slabs are fed through the following
furnace 242. The third embodiment operates substantially
identical to the two embodiments discussed above. The
third embodiment includes slab extractors 250, feed and run
back table 252, descaler 253, vertical edger 254, and hot
reversing mill 256 downstream of feed and run back table
252, upstream and downstream coiler furnace 258 and 260,
cooling station 262, coiler 266 downstream of cooling
station 262, coil car 267, a plate table 264, a shear 268,
a transfer table 270, and a final processing line 271 which
includes a plate side shear 272, plate end shear 274 and
plate piler 276.
Fig. 3B illustrates a modified version of the
embodiment of the caster and inline mill illustrated in
Fig. 3A. Fig. 3B is identical to Fig. 3A except that a
plurality of slab storage containers 280 and 280' is
provided adjacent the table conveyor 236. A second slab
storage container 280' obviously provides additional
capacity for storing cast slabs in the event of a delay
downstream. However, the addition of a second or more slab
storage container 280' also provides slab sequencing
possibilities. This allows for a certain prioritization
and changing of the order of slabs by directing them to
appropriate slab storage containers 280, 280' from which
the slabs can be selectively withdrawn.
Fig. 4 illustrates a first embodiment of the slab
storage container 280. The slab storage container 280
includes a carriage 282 mounted by rollers 284 onto a track
286 located within a slab holding pit 288. The walls 290
of the slab holding pit 288 are appropriately insulated as
is the top surface 292 of the carriage 282 which engages
and supports the lowermost slab of a stack of slabs. An
- 50 -
21 6~ 70~
insulated movable cover 294 is provided for covering the
slab holding pit 288 and the stack of slabs, as shown in
phantom in Fig. 4. Slab pushers 296 are provided for
moving slabs into and out of the stack in the slab storage
5 container 280. The slab storage container 280 operates as
follows. The lowermost slab of the stack of slabs is
pushed onto the top surface 292 of the carriage 282 by slab
pushers 296. Carriage 282 is then indexed down a distance
substantially equal to the thickness of the slab whereby a
second slab can be pushed by slab pusher 296 directly on
top of the initial slab. When the stack of slabs has been
placed into the slab storage container 280, the cover 294
can be positioned on top of the slab holding pit 288 to
maintain the heat within the slabs.
The configuration of the slab storage container
280 provides a simple and effective means for storing a
stack of slabs which also minimizes the space required.
Furthermore, stacking the slabs directly on top of each
other and maintaining the stacked slabs in contact with
20 each other gives the thermal advantages of a thicker slab.
The temperature loss of the individual slabs is minimized
with this stacked arrangement.
Fig. 5 is a side view of another embodiment of a
slab storage container 280 ' according to the present
25 invention. The slab storage container 280 ' includes a
carriage 282 ' supported on a frame 298. The carriage 282 '
is vertically movable on the frame 298. The carriage 282 '
includes a front and back pair of slab engaging arms 300.
As shown in Fig. 6, engaging points 302 of each engaging
arm 300 engage the sides of a lowermost slab in a stack of
slabs to engage and support the stack of slabs.
Preferably, the slab engaging arms 300 are hydraulically
operated to move into and out of engagement with the slabs.
In addition to moving in and out of engagement with the
35 slabs, the slab engaging arms 300 are preferably movable to
216570~1
accommodate various widths of the slabs. Side insulating
plate 304 and top insulating plate 306 are attached to each
slab engaging arm 300. As illustrated in Fig. 6, the top
insulating plates 306 of opposed slab engaging arms 300
5 will overlap with each other to allow for the movement of
the slab engaging arms 300 which provide for the
accommodation of varying widths of the slabs.
The slab storage container 280 ' operatés in a
m~nn~r similar to the slab storage container 280 described
above and provides similar advantages. In operation, the
carriage 282 ' is lowered to a position over a slab and the
slab engaging arms 300 are activated to securely clamp the
slab therebetween and the carriage 282 ' is again raised
holding the slab therein. To add a second slab to the slab
15 stack, the carriage 282' iS lowered, positioning the slab
on top of the second slab to be positioned in the stack.
Slab engaging arms 300 are disengaged from the first slab
carriage moved down to align the engaging points 302 with
the new lowermost slab in the stack and the slab engaging
20 arms 300 engage to contact the new lowermost slab in the
stack of slabs. This process is repeated until all of the
slabs are positioned within the stack and the process is
reversed for removing the slabs from the stack.
As discussed above, the slab storage container
25 280' provides the advantages of minimal space and
efficient, effective thermal conservation of the slabs as
with the slab storage container 280 described above. In
addition, the slab storage container 280 ' provides a system
that can be mounted directly over top of the slab conveyor
table, further minimizing the floor space required for the
overall system.
Although the present invention has been described
in considerable detail with reference to certain preferred
versions thereof, other versions are possible. Therefore,
35 the spirit and scope of the appended claims should not be
- -- 21657~0
limited to the description of the preferred versions
contained herein.
