Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02268603 1999-04-06
SLAB TRANSPORT ROLLER
FIELD OF THE INVENTION
The present invention relates to thin slab
transport rollers , for example , for use in the heating
furnace of a line for continuously casting thin slabs , and to
improvements in the process for assembling the roller.
BACKGROUND OF THE INVENTION
In iron mills , a heating furnace of the tunnel type
is disposed between an apparatus for continuously casting
thin slabs and rolling equipment , and a multiplicity of
transport rollers are arranged within the furnace .
FIGS. 12 and 13 show such a slab transport roller 1.
FIG. 13 is a view in section taken along the line XIII-XIII in
FIG. 12 and showing the roller as it is seen in the direction
of the arrows . As illustrated, the roller 1 comprises a
tubular body 10 , and a plurality of tires 20 arranged axially
of the tubular body 10 and fixedly fitted therearound. The
roller is connected to and rotatable by a rotating mechanism
( not shown ) . A cast slab 6 is supported by the peripheries of
the tires 20 and transported inside the furnace. Since the
furnace has a high-temperature atmosphere of at least about
1000 inside thereof, cooling water is passed through the
tubular body 10 for preventing the deflection or deformation
of the body 10 at high temperatures , and the tubular body 10
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is covered with a heat-insulating material 34 over its
peripheral surface except at the tire fixed portions
thereof .
The tires 20 are fixed to the tubular body 10 as by
welding. The covering of heat-insulating material 34 is
prepared by welding a multiplicity of studs 33 to the
peripheral surface of the tubular body 10 , coating the
surface with a monolithic heat-insulating material, such as
a castable, to a predetermined thickness and drying the
coating.
In the case of the transport roller described, the
heat-insulating material 34 separates off or dislodges owing
to a fall of slab scales, vibration or impact, failing to
effectively cover or protect the tubular body 10 and
consequently accelerating deformation of the tubular body
10 , wear thereon due to oxidation , or the like to shorten the
service life of the transport roller.
FIG. 14 shows another transport roller wherein the
heat-insulating material 34 is enclosed with a protective
member 60 made from a heat-insulating steel plate to preclude
the above drawback. The protective member 60 is made by
providing a hollow cylindrical member 61 around the
heat-insulating material 34 , covering opposite end faces of
the material 34 with respective annular side plates 63 , 63 ,
and welding each end edge of the cylindrical member 61 to the
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side plate 63.
However, much time and labor are required for
attaching many studs 33 to the tubular body 10 by welding.
Further since the protective member 60 is assembled after the
heat-insulating material 34 is applied and dried, the
application and drying of the heat-insulating material 34
necessitate a long period of waiting time. The transport
roller is therefore very inefficient to assemble.
The cylindrical member 61 of the protective member
60 is smaller than the tire 20 in outside diameter, so that
the protective member 60 can not be passed over the tire 20.
This gives rise to the need to alternately perform the work of
fixedly fitting the tire 20 around the tubular body 10 and the
work of installing the heat-insulating material 34 and
assembling the protective member 60 . Nevertheless , if much
labor and time are required to install the heat- insulating
material 34 and to assemble the protective member 60 as
stated above, the transport roller 1 is extremely
inefficient to make and necessitates a greatly increased
production cost.
An object of the present invention is to overcome
the foregoing problems involved in producing slab transport
rollers by providing an improved protective member for
enclosing the heat-insulating material.
SUMMARY OF THE INVENTION
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To fulfill the above object, the present invention
provides a slab transport roller which comprises a tubular
body having tires fixedly fitted therearound, and a
heat-insulating sleeve provided around the tubular body
except at the tire fixed portions thereof , the
heat-insulating sleeve comprising a tubular case and a
heat-insulating material, the tubular case including an
inner cylindrical wall and an outer cylindrical wall
arranged concentrically so as to form an annular space
therebetween, and a pair of side walls closing the annular
space at opposite ends of the cylindrical walls , the
heat-insulating material being accommodated in the annular
space of the tubular case .
The present invention also provides a process for
assembling the slab transport roller described which process
has the steps of fixedly fitting the tires around the tubular
body, fitting the heat-insulating sleeve around the tubular
body with the heat-insulating material accommodated in the
annular space of the tubular case, and fixing the tires to or
lockingly engaging the tires with the tubular case of the
heat-insulating sleeve.
According to the invention, the heat-insulating
sleeve is produced preferably by a process comprising the
steps of forming a foam replica of the tubular case with the
heat-insulating material accommodated in the annular space,
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preparing a mold for lost-foam casting by enclosing the foam
replica in molding sand within a casting container and
removing air from the sand by suction to compact the sand, and
placing a molten heat-resistant alloy for forming the
tubular case into the casting container to replace the foam
replica by the heat-resistant alloy.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view in section partly broken away
and showing a transport roller embodying the invention;
FIG. 2 is a view in section taken along the line
II-II in FIG. 1;
FIG. 3 is a perspective diagram showing an
embodiment of tubular case of the invention;
FIG. 4 is a perspective diagram showing a foam
replica for preparing the tubular case of the invention as a
cast body with a heat-insulating material accommodated
therein;
FIG. 5 is a sectional view showing a lost-foam
casting container with a foam replica and molding sand
accommodated therein;
FIG. 6 is a view in axial section of a heat-
insulating sleeve and a tire to show a mode of engagement
therebetween according to the invention;
FIG. 7 is a view in axial section the heat-
insulating sleeve and the tire to show another mode of
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engagement therebetween according to the invention;
FIG. 8 is a side elevation showing another
embodiment of tubular case of the invention;
FIG. 9 is a view in section taken along the line
IX- IX in FIG . 8 ;
FIG. 10 is a side elevation of an embodiment of tire;
FIG. 11 is a view in section taken along the line
XI-XI in FIG. 10 and showing the tire;
FIG. 12 is a front view partly broken away and
showing a conventional transport roller;
FIG. 13 is a view in section taken along the line
XIII-XIII in FIG. 12; and
FIG. 14 is a view in axial section showing another
example of conventional transport roller.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below in
detail with reference to the embodiments shown in the
drawings.
FIGS . 1 and 2 show an embodiment of transport roller
of the present invention. FIG. 2 is a view in section taken
along the line II-II in FIG. 1.
Heat-insulating sleeves 3 fitted around a tubular
body 10 each comprise a tubular case 30 and a heat- insulating
material 34. As illustrated, the tubular case 30 comprises
an inner cylindrical wall 36 and an outer cylindrical wall 37
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which are arranged concentrically and opposed to each other
so as to form an annular space therebetween, and a pair of
annular side walls 38 , 38 closing the annular space at
opposite ends of the cylindrical walls . SUS 310S steel or
like heat-resistant material is suitable for making the
tubular case 30 as a material capable of withstanding the
interior high-temperature atmosphere of the heating
furnace .
The annular space formed in the tubular case 30 is
filled with the heat-insulating material 34 . Examples of
suitable materials for use as the heat-insulating material
34 include various monolithic materials, such as castables,
which are conventionally used, alumina, zinc oxide and like
other ceramic fibers .
According to the invention, the inner cylindrical
wall 36 of the tubular case 30 can be provided on its outer
peripheral surface with studs 33 (e.g. , V-shaped or Y-shaped
studs ) for supporting the heat-insulating material 34 when
so desired as in the prior art . The studs 33 may be provided
on the inner peripheral surface of the outer cylindrical wall
37 of the tubular case 30.
The heat-insulating sleeve 3 of the invention is
produced by the process to be described below in detail.
According to a first preferred embodiment, a member
for the inner cylindrical wall 36 of small diameter, a member
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for the outer cylindrical wall 37 of large diameter and
members for the pair of annular side walls 38 , 38 are prepared
for making the tubular case 30. The heat-insulating sleeve 3
is fabricated by arranging the member for the wall 36 and the
member for the wall 37 concentrically as opposed to each
other to form an annular space, filling the heat-insulating
material 34 into the space, and welding the members for the
pair of side walls 38 , 38 to the members for the walls 36 , 37
at opposite ends of the latter members .
If holes 72 for filling the heat-insulating
material 34 therethrough are formed in the annular side walls
38 , 38 , with corresponding caps 73 prepared for the holes 72
as seen in FIG. 3, the heat-insulating material 34 can be
filled into the annular space of the tubular case 30 through
the holes 72 even after the case 30 is formed by closing the
opposite open ends of the inner and outer cylindrical walls
36 , 37 with the annular side walls 38 , 38 . In this case , the
holes 72 are closed with the caps 73 after the material 34 has
been completely filled in.
According to a second preferred embodiment , the
heat-insulating sleeve 3 having the heat-insulating
material 34 accommodated in the annular space of the tubular
case 30 is produced by the lost-foam process . This process
will be described with reference to FIGS. 4 and 5.
FIG. 4 shows the components of a foam replica 40 to
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be made of a foam such as expanded polystyrene .
As illustrated, an inner cylindrical wall member 46
and an outer cylindrical wall member 47 both made of the foam
are arranged concentrically to form an annular space between
the two members . After the heat-insulating material 34 is
filled into the annular space formed, opposite open ends of
the wall members 46 , 47 are closed with annular side wall
members 48, 48 similarly made of the foam by joining the
members 48 to the members 46, 47 with an adhesive. In this
way, the foam replica 40 is formed with the heat-insulating
material 34 contained in the annular space.
When studs 33 are to be provided, for example, on the
inner cylindrical wall 36 as previously described with
reference to the embodiment of transport roller, rod members
43 corresponding to the studs in shape are prepared from the
foam and attached to suitable portions of outer periphery of
the inner cylinder wall member 46 with adhesive .
Next, the foam replica 40 thus formed is placed into
a casting container 50 and enclosed in molding sand 51 as
shown in FIG. 5. With the upper portion of the container 50
covered with a vinyl sheet (not shown) , a suction nozzle is
inserted into the container 50 , and air is removed from the
sand 51 by suction using suction means such as a vacuum pump,
whereby the sand 51 is compacted to shape a mold for lost-foam
casting. A melt of heat-resistant alloy for forming the
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tubular case 10 is poured into the container in this state,
whereupon the foam portion of the replica 40 disappears under
the action of heat of the molten metal, and the molten metal
fills the lost portion and solidifies, whereby a cast body is
obtained with the heat-insulating material 34 enclosed
therein. In this way, the heat-insulating sleeve 3 is
produced with the heat-insulating material 34 accommodated
in the annular space of the tubular case 30 at the same time .
The lost-foam process for casting can be practiced
in the usual manner without necessitating special conditions
or additional limitations , with the exception of filling the
heat-insulating material 34 into the interior of the foam
replica 40 , efficiently affording a composite body with high
reliability with respect to the shape and construction.
As already described above , the transport roller 1
of the invention comprises a tubular body 10 , tires 20
fixedly fitted around the tubular body at a plurality of
portions of the body spaced apart axially thereof , and
heat-insulating sleeves 3 provided around the tubular body
except at the tire fixed portions thereof and each having a
heat-insulating material 34 accommodated in an annular space
of a tubular case 30. The transport roller 1 of the invention
is assembled by the process to be described below.
First, a tire 20 is fixedly fitted around the
tubular body 10 at the approximate midportion of its length.
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The tire 20 comprises, for example, the combination of a
tire body 21 and support frames 22 for supporting the tire
body. For the prevention of idle rotation, the support
frames 22 are secured to the tubular body 10 as by welding.
Heat-insulating sleeves 3 , 3 of the invention each
having the heat-insulating material 34 contained in the
annular space of the tubular case 30 are then fitted
respectively to opposite sides of the tire 20.
Next tires 20, 20 are fitted to the outer sides of
the respective sleeves 3 , 3 and secured to the tubular body
10. The transport roller is assembled by repeating this
procedure axially outwardly of the tubular body 10 in
succession.
In fixedly fitting the tires 20 around the tubular
body 10, one tire 20 may be mounted first at one end of the
tubular body 10 , or the sleeve 30 may be mounted first on the
tubular body.
To render the heat-insulating sleeve 3 rotatable
with the tubular body 10 , it is necessary to secure the sleeve
3 directly to the surface of the tubular body 10 as by
welding, or to fix the sleeve 3 to the side portion of the
tire 20 secured to the tubular body 10 , or to engage the
sleeve 3 with the tire 20 secured to the body 10.
The heat-insulating sleeve 30 can be lockingly
engaged with the tire 20 according to one of the following
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embodiments.
For example as shown in FIG. 6, a key member 83 is
provided on the tire body 21 of the tire 20 , and a key groove
85 corresponding to the key member is formed in the side wall
38 of the tubular case 30 of the sleeve 3 so as to engage the
sleeve 30 with the tire 20 by rotating the tubular member 10 .
Alternatively, the key member 83 may be formed on the side
wall 38 of the sleeve tubular case 30, with the key groove 85
formed in a side portion of body 21 of the tire 20 as shown in
FIG. 7.
Further alternatively as shown in FIG. 8,
projections 87 are provided on the outer side surface of side
wall 38 of the sleeve tubular case 30 at respective portions
spaced apart circumferentially thereof (at three portions
spaced apart by an angle of 120 degrees about the center in
the illustrated embodiment), and bores 89 corresponding to
the projections are formed in the support frames 22 of the
tire 20 as shown in FIGS. 10 and 11. The sleeve 3 can be
engaged with the tire 20 by inserting the projections 87 into
the respective bores 89 as seen in FIG. 9.
As is the case with the key member and the key groove
described, the projections 87 may be formed on side portions
of the tire 20 to fit into bores 89 formed in the side wall 38
of the sleeve tubular case 30.
In the case where the key member 83 or each
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projection 87 is to be provided on the side wall 38 of the
tubular case 30 by the lost-foam process , a member
corresponding to the key member 83 or projection 87 in shape
is prepared from a foam and attached with adhesive to a
suitable portion of the side wall member 48 of the foam
replica 40 with adhesive before preparing the mold.
With the embodiment wherein the heat-insulating
sleeve 3 is in engagement with the tire 20 , the sleeve 3 is
free to thermally expand when the roller is exposed to the
high-temperature atmosphere within the furnace, imposing no
stress on the tire 20 or tubular body 10 and causing no
deformation .
The heat-insulating material 34 is accommodated in
the annular space of the tubular case 30 of the sleeve 3 in
advance , so that the invention , unlike the prior art , does
not require a long period of waiting time for the application
and drying of the heat-insulating material in assembling the
transport roller, while the sleeve 3 can be fitted around the
tubular body 10 with extreme ease within a short period of
time.
The transport roller of the invention includes
heat-insulating sleeves each having the heat-insulating
material accommodated in the annular space of tubular case .
The tires and heat-insulating sleeves can therefore be
fixedly fitted around the tubular body alternately easily
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and efficiently. This is very useful for achieving an
improved efficiency and a cost reduction in producing the
transport roller.
Various modifications can be made by one skilled in
the art within the scope of the invention as defined in the
appended claims.
For example, an additional heat-insulating sleeve
3a can be provided around the tubular body 10 and held thereto
by a retainer 70 in a region thereof toward its end as seen in
FIG. 1 to protect the tubular body in this region and prevent
the axial displacement of the sleeve 3.
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