U.S. patent number 3,651,857 [Application Number 05/050,465] was granted by the patent office on 1972-03-28 for device for supporting and cooling continuously cast strands of metal.
This patent grant is currently assigned to Demag Aktiengesellschaft. Invention is credited to Wilhelm Koch.
United States Patent |
3,651,857 |
Koch |
March 28, 1972 |
DEVICE FOR SUPPORTING AND COOLING CONTINUOUSLY CAST STRANDS OF
METAL
Abstract
A supporting device for supporting cast strands of metal as they
are fed from a casting mold, comprises a supporting frame which is
adapted to be positioned adjacent the casting mold and which
carries a plurality of longitudinally spaced rows of transversely
extending cross members. Each cross member carries a plurality of
supporting members in the form a rotatable rolls which are arranged
in transversely spaced orientation with the supporting members of
adjacent rows being laterally offset and extending between the
adjacent support members of each next adjacent row. The supporting
members are dimensioned as small as possible and the cross member
advantageously includes means for directing a fluid spray outwardly
in a pattern to provide adequate cooling for the casting which is
supported on the device.
Inventors: |
Koch; Wilhelm (Duisburg,
DT) |
Assignee: |
Demag Aktiengesellschaft
(Duisburg, DT)
|
Family
ID: |
5748602 |
Appl.
No.: |
05/050,465 |
Filed: |
June 29, 1970 |
Foreign Application Priority Data
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Oct 18, 1969 [DT] |
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P 19 52 633.1 |
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Current U.S.
Class: |
164/448; 134/83;
134/199; 164/444; 164/485 |
Current CPC
Class: |
B22D
11/128 (20130101) |
Current International
Class: |
B22D
11/128 (20060101); B22d 011/12 () |
Field of
Search: |
;164/82,89,282,283
;134/49,64,82,83,122,165,199 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,399,695 |
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Apr 1965 |
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GB |
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153,721 |
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Mar 1956 |
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SW |
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Primary Examiner: Annear; R. Spencer
Claims
I claim:
1. A supporting device for supporting casting strands of metal as
they are fed from a casting mold, comprising a supporting frame
adapted to be positioned adjacent the casting mold, a plurality of
longitudinally spaced rows of transversely extending cross members
supported on said frame, a plurality of supporting members on said
cross members arranged in transversely spaced orientation with the
supporting members of adjacent rows being laterally offset and
extending between the adjacent support members of each next
adjacent row, said supporting elements being dimensioned as small
as possible, and including cooling means for supplying a coolant
through said cross members directly to the casting strand and for
discharging the coolant between said supporting members along the
length of said cross members.
2. A supporting device, according to claim 1, wherein said support
members comprise disk shaped supporting rollers.
3. A supporting device, according to claim 1, wherein said
supporting frame includes a bearing block at each side, said cross
members being supported at each end in respective bearing blocks,
said supporting members being rotatably supported on said cross
members.
4. A supporting device, according to claim 1, wherein said
supporting elements comprise supporting plates disposed in rows,
said plates being spaced apart to define gaps into which the plates
of the next adjacent rows extend with clearance.
5. A supporting device for supporting casting strands of metal as
they are fed from a casting mold, comprising a supporting frame
adapted to be positioned adjacent the casting mold, a plurality of
longitudinally spaced rows of transversely extending cross members
supported on said frame, a plurality of supporting members on said
cross members arranged in transversely spaced orientation with the
supporting members of adjacent rows being laterally offset and
extending between the adjacent support members of each next
adjacent row, said cross members comprising hollow shafts defining
a passage for a coolant liquid, a plurality of cooling nozzles on
said shaft communicating with said passage and arranged to
discharge the liquid in a direction toward said strand and being
located between said supporting members.
6. A supporting device, according to claim 5, wherein said nozzles
are oriented oblique to the strand surface and directed into the
space between the two adjacent supporting members of the next
adjacent rows.
7. A supporting device, according to claim 1, including two
supporting frames comprising an upper supporting frame and a lower
supporting frame each carrying said cross members and said
supporting members, and spacer means between said frames for
holding said frames at a width comparable to the width of the
strand to be moved between said frames.
8. A supporting device, according to claim 7, wherein said spacer
means includes shims for varying the spacing between said frames to
accommodate variations of strand thickness.
9. A supporting device, according to claim 1, wherein said cross
members include recess portions between adjacent supporting members
defining a space for receiving the supporting member of the next
adjacent row.
10. A device, according to claim 9, wherein said supporting members
are of circular cross section, the recess being formed by a flat
portion of said cross section.
Description
SUMMARY OF THE INVENTION
This invention relates in general to continuous casting apparatus,
and in particular, to a new and useful supporting device
particularly for cast steel strands which includes a plurality of
supporting elements with spray means for spraying a cooling fluid
in the vicinity of a casting which is supported.
Usually the cast strand solidifies in the continuous casting mold
only to the extent of having, upon leaving the mold, a relatively
thin skin consisting of cast metal below the point of liquidity. In
this condition the strand easily tends to bulge at the supporting
elements which for example, may comprise either rollers, rolls or
plates. Such bulging entails the danger of the strand breaking and
the bulges increase the transport resistance, the individual
resistances adding up to a total resistance which must be overcome
by the strength of the strand transporting machine. Therefore the
greater the friction at the bulges, the greater the drawing
resistance and the greater the driving output of the transporting
machine. In addition, the stress on the strand skin will be great
and this skin is usually weak to start with and this could produce
particularly serious consequence. In practice therefore, an
increase in the casting speed and an increase in output are
possible in rare cases.
The slower that the strand is cooled the more is the danger that
the strand will break off provided the casting speed is increased.
In order to prevent bulges or breaks, the strand is supported,
after it leaves the mold, and it is cooled at the same time. The
more intensive the cooling, the more the skin growth is
accelerated. Therefore, the process of supporting and cooling goes
hand in hand and can methodologically not be separated. This
results in problems involving the known supporting devices with
which the cooling devices must be associated.
It is known to dispose through rollers at the broad side of the
strand at a location below the continuous casting mold for
instance, where slabbing strands are involved. The greater the
roller diameter selected, the greater the distance between the
several rollers. It is also known to attach one or two such rollers
directly to the continuous casting mold while the others are
mounted in a stationary supporting device. The roller spacings must
be chosen so that there is the possibility of providing a number of
spray nozzles to cool the strand appropriately between each two
rollers over the entire width of the strand. It is also known to
provide several metal plates below the continuous casting mold,
so-called cooling shoes, which support the strand at the sides of
its profile. The metal plates form closed cooling boxes with a
definite system of plate arrangement in order to cool the latter as
well as bring coolant to the strand in addition. However, the metal
plates cover the strand to such an extent that the desired cooling
effect fails to materialize for reasons of the so-called
Leidenfrost phenomenon. The coolant which gets between the strand
surface and the metal plate through the internal holes evaporates,
thereby developing an insulation effect which is a known attribute
of water vapor. Fresh coolant can flow only under difficulties and
the developed vapor remains too long, therefore, to cause a cooling
effect to the desired degree. Consequently, unless success is
achieved in rinsing away the water vapor in time and at least to
replace it by vapor of lower temperature, to effect the heat
dissipation by evaporating the coolant, the cooling effect is
insufficient and therefore the strand skin growth is also poor. An
advantage inherent in the metal plates, namely the direct contact
of the strand with the plate surface is therefore overcome by the
disadvantages described.
In order to eliminate the above described disadvantages, it is now
known to provide alternating rows of large and small supporting
rollers on a fixed shaft member and to have each of the two
neighboring rollers of larger diameter of the next adjacent shaft,
in the travel direction of the strand, arranged in opposition to a
smaller protective part of the proceeding shaft. This is done in an
attempt to support the strand on its surface by bearing points in
the manner of a honey-comb pattern in order to keep the bulges
small. Obviously, however, only the goal of support is achieved
without giving the specialist an instruction on how also to solve
the problem of better cooling because a disadvantageous covering
effect respecting the coolant is inherrent with such a gridlike
supporting element arrangement. Therefore, cooling water can
penetrate only between the remaining gaps of the various roller
diameters, that is, between the small and the big rollers. A
desired cooling effect is consequently lacking. However, the
configuration of the big rollers provided also brings with it the
disadvantage of having to dimension the mutual spacing of the
stationary shafts by a correspondingly greater amount as a function
of the diameter of the big rollers. Therefore, in reality, two
difficulties have not been overcome by the known solution. The one
relates to the transmission of large forces to the strand skin, by
the larger diameter rollers as the size of the honey-comb pattern
increases and the other disadvantage relates to the possibility of
cooling the strand which ultimately can only be drawn readily if
the strand skin growth can be improved so that the greater
resistance due to bulging disappears. Accordingly, the emphasis in
the known object is on the support neglecting the cooling
aspect.
In accordance with the present invention, there is provided a
supporting device which is capable of distributing the supporting
forces even better and above all takes into a better account the
possibilities for cooling. With the inventive construction, the
supporting elements are arranged on transverse members or cross
shafts at definite spaced relationship in longitudinal rows of
shafts with the supporting members on adjacent shafts being
disposed between two adjacent supporting members of the next
adjacent row. The dimensions of each supporting element is selected
as small as possible and partial lengths of each cross support or
shaft is kept free for the inclusion of a cooling device. This
provides a close checker boardlike support and small gaps remain
between the supporting elements which permit the dissipation of the
steam from the cooling liquid. One advantage is that the strand is
better supported by unit of area due to the more densely staggered
supporting elements so that strand is subjected to less bulging
than heretofore. The frequency of the points of contact of the
supporting elements on the surface of the strand also permits the
dissipation of a greater amount of heat.
Making the network of the supporting points or tacking points of
forces denser protects the strand, particularly immediately
adjacent the continuous casting mold so that surface cracks are
avoided. Consequently the supporting forces may be weaker, and,
despite the denser network of supporting forces, the strand is
cooled better and there is also cooling of the rollers and cooling
of the shafts supporting the rollers from the outside. The cooling
is advantageously provided by conducting a cooling liquid through
the shafts and discharging it through nozzles arranged between the
individual supporting elements. This means that no separate nozzle
system with separate conduit supplies are required and such systems
are usually cumbersome particularly in case the strand breaks off
and they hinder the readjustment to different casting strand
dimensions. In contrast thereto a cooling device disposed on the
shaft elements in the gaps between the supporting members always
maintains the same spacing from the strand.
The supporting elements are advantageously disk shaped supporting
rollers which are arranged at spacings greater than the disk width
and which extend at their outer peripheries closely to the next
supporting shaft of the next row. The supporting shafts are mounted
in side blocks of a machine frame and the supporting elements are
thus supported almost without friction so that the drawing
resistance can be kept smaller precisely at that part of the strand
skin which is particularly thin. It is possible therefore according
to the invention, to provide for greater casting speed.
The above implementation form operates with less friction due to
the fact that the supporting elements are mounted for rolling
movement. However, in certain cases in which heat dissipation
should be particularly great it is especially advantageous if the
supporting elements consist of plates disposed in rows, with the
rows having gaps into which the plates of the adjacent support
members extend. Each plate is connected to the support member by an
arm. Here again, the gaps between the plates and the support
members are sufficiently great so that water vapor can be
dissipated readily. Consequently, a particularly advantageous motor
cooling consists in providing for heat transfer to the plate solely
by contact with the strand and cooling the plates externally by
spraying cooling water on them. This creates similar conditions of
heat dissipation as exist in the continuous casting mold except
that such small plates shape supporting elements cannot be provided
inside a continuous casting mold so that the specialist has so far
been prevented from employing them in the lower regions of the
casting mold. The multiplicity of supporting elements of plate
shape therefore permits the disposition of a relatively short frame
under the continuous casting mold or of course the provision of a
combination of rollers and plates. Consequently, it is desirable
that the plates be arranged contiguous to the continuous casting
mold and a short distance thereafter a frame with cross shafts or
supports to which the disk rollers are attached.
In a further development of the invention, there are added
particularly inventive measures which improve the cooling effect.
The cross members of shafts are made hollow and these hollow
interior shaft passages supply the coolant to nozzles which are
arranged thereon to discharge the coolant against the surface of
the strand and they are oriented in the gap between two supporting
elements. This measure combines two advantageous measures
simultaneously. The cross shafts themselves are cooled and
therefore dissipate amounts of heat absorbed by heat radiation and
at the same time the space still available between two supporting
elements is utilized to introduce cooling water. Such a
construction is superior to the state of the art because separate
spray nozzle lines comprising a multiplicity of longitudinal and
transverse lines are obviated, thus facilitating especially the
readjustment of the supporting device to a new strand dimension.
For a long time the complicated structure of the coolant supply
system has been a great hinderance to the specialist in case of
strand breakages which are now eliminated.
An improved cooling effect can be achieved by orienting the center
line of the nozzles obliquely to the strand surface and into the
space between two supporting rollers. In practice this accomplishes
an adaptation of the cooling system to the checker boardlike
supporting system. No longer is there a gap between the various
impact areas of the jet spray nozzles. Consequently the strand is
cooled more intensely than heretofore. The cooling action
considered over the width of the strand is also more uniform. An
area of the strand once cooled will not get into a zone which is
not charged by coolant for a longer period of time.
A further improvement of the invention comprises the use of
additional cooling lines between the hollow interiors of the cross
shafts and an outside diameter of the supporting roller shaft which
serves as a journal. These branch offs from the interior of the
cross shafts serve either for the cooling of the supporting roller
journal or the cooling of the bearing point itself and bring about
a certain lubricating effect.
The principal of internal cooling can also be further developed by
arranging a group of cross shafts with supporting elements within a
frame structure with one or more frame members which themselves
provide means for conducting a coolant material. Using the
longitudinal means of the cross frame for the conducting of the
liquid coolant also permits a connection of this cross frame member
to the individual supporting shafts for conducting the coolant out
to the nozzle members located along the length of the cross
shafts.
In accordance with further characteristics between the upper and
the lower beam parts are arranged spacers, the length of which may
be varied by means of shims in accordance with different strand
thicknesses. This measure serves to set up the supporting device
symmetrically with the spacing, always remaining uniform and
limiting the efforts and time required for changing over. The basic
suggestion of the checker board-type arrangement for the supporting
of the strand plus the cooling arrangement provides an improved
supporting and cooling feature. The supporting elements themselves
in the form of rollers supported on the cross shafts may be such
that they extend at their periphery into recesses defined on the
cross shafts for this purpose.
Accordingly, it is an object of the invention to provide an
improved device for supporting and cooling a strand from a
continuous casting machine which includes a supporting frame having
a plurality of longitudinally spaced rows of transversely extending
cross members supported on the frame and a plurality of supporting
members on the cross members arranged in transversely spaced
orientation with the supporting members of adjacent rows being
laterally offset and extending between adjacent supporting members
of the next adjacent row and which further advantageously includes
means for supplying a coolant at selected locations along the
supporting members.
A further object of the invention is to provide a supporting
structure for use in association with a continuous casting mold and
which advantageously includes a cross member associated with the
exit of the mold having at least one supporting member extending
across the width thereof and carrying a plurality of spaced
supporting members thereon, said cross member including means for
directing a cooling spray from the supporting member at the
locations between the supporting elements.
A further object of the invention is to provide a continuous strand
supporting and cooling device which is simple in design, rugged in
construction and economical to manufacture.
The various features of novelty which characterize the invention,
are pointed out with particularity in the claims annexed to and
forming a part of this specification. For a better understanding of
the invention, its operating advantages and specific objects
attained by its use, reference should be had to the accompanying
drawings and descriptive matter in which there is illustrated and
described a preferred embodiment of the invention .
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a top plan view of a supporting device for supporting
cast strands of metal constructed in accordance with the
invention;
FIG. 2 is a section taken along the line II--II of FIG. 1;
FIG. 3 is a section taken along the line III--III of FIG. 1;
FIG. 4 is an enlarged partial sectional view of a portion of FIG.
2; and
FIG. 5 is a view of a portion of the device indicated in FIG. 1
showing the arrangement of the spray means for cooling.
GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in particular, the invention embodied
therein comprises a supporting device generally designated 2 which
is arranged adjacent the discharge of a continuous casting mold 1
which is filled continuously with a liquid metal. In the embodiment
shown, the continuous casting mold carries projecting portions or
brackets 3 and 4 at its underside 5 which together with
intermediate projecting brackets 7 and 8 support a cross member or
shaft 6. In accordance with a feature of the invention, the
plurality of supporting elements in the form of plates or rollers 9
are rotatably mounted on the shaft 6 and they are arranged to
engage and run with the movement of the continuous casting strand
28 which is delivered from the mold 1.
In accordance with a further feature of the invention, the
supporting frame 2 is mounted at a spacing 11 away from the
supporting elements 9 which are directly adjacent the discharge of
the continuous mold 1. The supporting device 2 is made up as a
partial section 12 which may extend for example in a slabbing
machine for one or two meters below the casting mold 1 after which
may be arranged the known type of supporting devices because
controlled cooling is no longer required.
Each partial section 12 includes right and left longitudinal beams
13 and 13' which are interconnected by upper and lower cross beams
15 and 14, respectively. Spacer beams 16 and 17 are arranged
between the cross beams 14 and 15 to form the entire frame of the
partial section 12. The partial section 12 may of course be
repeated several times in the travel direction of the strand
28.
In accordance with a further feature of the invention, the frames
include side support blocks 22 and 23 which support cross support
members generally designated 20 in the form of shafts 21 which are
mounted in the blocks 22 and 23. The shafts 21 are arranged in
longitudinally spaced transverse rows and each shaft carries a
plurality of supporting members 18 in the form of rotatable rollers
19 which are arranged in spaced transverse relationship. The
rollers 19 are mutually spaced by a distance 24 in such a manner
that a roller of each row is arranged between two adjacent rollers
of the next adjacent row in the space 24 and without its
circumference 25 touching the surface 26 of the shaft 21. Gaps 27
are thus created through which steam can be continuously dissipated
without trouble.
In FIG. 2, it is seen that the rollers 19 are arranged as close to
each other as possible and their peripheries 25 intersect. The
strand 28 involves a slab profile as indicated in FIG. 3 and
therefore the dimensioning factors governing the supporting device
are based on a steel slab strand. The longitudinal beams 13 are
hollow so that cooling water may flow through them in case no
separate lines are provided for this purpose. The shafts 21 are
also made hollow and are advantageously provided with a center
cavity or passage 29 for a coolant such as water. Coolant nozzles
30 are arranged along the length of the shafts and they connect to
the passages 29. They are oriented so that the discharge 31 extends
obliquely to the surface 32 of the strand as shown in FIG. 4. In
the arrangement shown in FIG. 5, however, the shape of the spray
jet 33 may result in an uninterrupted spray surface over the width
of the cast strand 28. Accordingly with the inventive arrangement
the cooling of the strand is more uniform and it has the particular
advantage that no interruptions of spray areas will occur when
other strand dimensions are involved. When modifying this spacing
to accommodate a new strand dimension the spacing of the nozzles
from the strand will remain the same because the diameter 25 of the
rollers 19 will be the same and therefore the shafts 21 will also
be the same, thus preserving the spacing of the spray orifices
33.
In the arrangement shown in FIG. 4, the nozzles are oriented at an
angle to each other but of course a single nozzle having a center
line oriented perpendicular to the strand may also be provided or
be provided alternatively if desired. A particularly intensive
cooling action is obtained when perpendicular nozzles as well as
oblique ones are provided and neither of these kind need
necessarily be oriented in the plane of FIG. 4. In the arrangement
shown in FIG. 5, such nozzles oriented obliquely against the
surface of the strand form an uninterrupted spray area over the
width of the strand. These nozzles are expediently designed in the
form of flat jet nozzles but solid or hollow cone nozzles may also
be employed.
According to FIG. 4, the coolant nozzles 30 are advantageously
mounted so that their sprays will meet at the location T/2 on the
strand surface. T signifies the spacing of the rollers 19 running
one behind the other in one strand width sector. There are further
coolant lines 33 extending from the central passage 29 and the
outside of the profile 34 of the shaft 21. It is through these
lines that the coolant reaches, as a lubricant, the race between
the roller 19 and the shaft 21 which is not shown.
The invention is applicable quite generally to all strand
thicknesses and is particularly advantageous for slab strands.
Adjustment to various strand dimensions can be made due to the
spacers 16 and 17 and the shims 35 of various thickness.
It is possible to spray with traditional spray nozzles into the
still remaining gaps of the checker boardlike arrangement of the
rollers 19 which, however, means the application of the invention
in a most simple form. Optimum cooling action is attained in that
the coolant nozzles 30 and the central passage 29 are employed to
distribute the coolant. This also increases the efficiency of the
cooled rollers. An even closer configuration of the supporting
rollers 19 can be achieved by making the outside diameter 34 of the
shafts 21 with a flat 36 so that the periphery 25 of a roller 19
can be brought even closer to the shaft 21. The flat 36 need not
necessarily be designed as drawn but may comprise a recess 37
produced by a tool having a slightly larger diameter than the
diameter 25 of the supporting roller 19.
* * * * *