Information
-
Patent Grant
-
6402507
-
Patent Number
6,402,507
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Date Filed
Friday, October 20, 200023 years ago
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Date Issued
Tuesday, June 11, 200222 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
- Brinks Hofer Gilson & Lione
-
CPC
-
US Classifications
Field of Search
US
- 432 60
- 432 228
- 432 236
- 432 246
- 492 30
- 492 46
- 193 37
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International Classifications
-
Abstract
A tunnel or reheat furnace roller assembly includes a hollow tube or arbor of low alloy steel and an inner concentric tube for providing a flow of cooling water. About the exterior of the tube or arbor is cast a surround or jacket having larger diameter, spaced apart wheels which engage and support workpieces in the furnace and integrally formed intermediate smaller diameter regions. The integral surround is preferably cast of Waspaloy or other high temperature, nickel alloy steel.
Description
BACKGROUND OF THE INVENTION
The invention relates generally to water-cooled rollers for tunnel or reheat furnaces and more specifically to water-cooled rollers for tunnel or reheat furnaces having integrally cast rollers and intermediate regions disposed on the exterior of a hollow shaft or arbor.
The production of steel billets, bars, plates, slabs and strips may be accomplished continuously through a continuous vertical pour from a tundish which is quickly cooled by water spray and shaped in a series of opposed pairs of rollers. The rollers describe an arc extending from a vertical to a horizontal orientation where the material is sheared into appropriate lengths. Typically, such rapid cooling cools the exterior of the material sufficiently so that it can be handled and treated but leaves the interior at a much higher temperature, in a nearly molten state.
In order to equalize the temperature throughout the metal, it is next provided to a tunnel or reheat furnace which provides both a defined residence time and exterior reheating to achieve temperature uniformity throughout the workpiece in order to facilitate subsequent forming operations. In the tunnel furnace, the metal is moved along a plurality of rollers while being reheated by a plurality of natural gas-fired heaters disposed along the furnace.
Clearly, the service conditions of the rollers, operating in an environment of 2000° F. (1095° C.) to 2300° F. (1260° C.), carrying metal bars or slabs at the same temperatures and subjected to cyclic loading from the individual bars or slabs carried thereover are best described as inhospitable. Furthermore, the gas heaters generally operate with excess air and thus the atmosphere within the furnace is an oxidizing atmosphere. Such operating conditions conspire to shorten the operating life of tunnel furnace rollers. Furthermore, while teardown and replacement of such rollers in a furnace is, in itself, costly, the down time of the steel producing facility can represent an even greater expense.
Accordingly, significant effort has been directed to improving the performance and extending the service life of such furnace rollers. U.S. Pat. Nos. 3,860,387 and 4,991,276 teach furnace rollers having inner arbors, outer tubes and tires which support the metal slabs or plates as they pass through the furnace.
U.S. Pat. No. 5,230,618 teaches an insulated furnace roller wherein a refractory is cast about the arbor in regions intermediate the tires which support the slabs or plates in the furnace. Products incorporating the just recited technology exhibit improved service life over prior devices.
From the foregoing, it is apparent that the cost of replacement calculated as both the actual cost of roller replacement and down time of the furnace continues to support efforts to develop and improve tunnel furnace rollers. The present invention is directed to such an improved device.
SUMMARY OF THE INVENTION
A tunnel or reheat furnace roller assembly includes a hollow tube or arbor of low alloy steel and an inner concentric tube for providing a flow of cooling water. About the exterior of the tube or arbor is cast a jacket or surround having a plurality of larger diameter, spaced apart wheels which engage and support workpieces in the furnace and integrally formed intermediate smaller diameter regions. The integral surround is preferably cast of Waspaloy or other high temperature, nickel alloy steel. Waspaloy is a trademark of United Technologies, Inc. for its brand of high temperature, nickel alloy steel. The wheels are preferably slightly offset from the longitudinal center of the roller assembly and alternate roller assemblies are reversed end to end when installed in the furnace such that the wheels present an evenly and equally offset or staggered wheel pattern.
Thus it is an object of the present invention to provide a furnace roller having wheels or tires and integrally cast intermediate regions of smaller diameter.
It is a further object of the present invention to provide a furnace roller having integrally cast wheels or tires and intermediate regions of smaller diameter disposed upon a water-cooled tubular shaft or arbor.
It is a still further object of the present invention to provide a furnace roller having integrally cast wheels or tires spaced apart by smaller diameter intermediate regions fabricated of Waspaloy.
It is a further object of the present invention to provide a furnace roller installation wherein wheels of adjacent roller assemblies are arranged in an offset or staggered pattern.
It is a still further objection of the present invention to provide a furnace roller having integrally cast wheels and intermediate regions which exhibit improved service life.
Further objects and advantages of the present invention will become apparent by reference to the following description of the preferred embodiment and appended drawings wherein like reference numbers refer to the same component, element or feature.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top, plan view of a tunnel or reheat furnace utilizing rollers according to the present invention;
FIG. 2
is a full, sectional view of a furnace roller according to the present invention disposed in a tunnel or reheat furnace and taken along line
2
—
2
of
FIG. 1
; and
FIG. 3
is an enlarged, fragmentary view of a furnace roller according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to
FIG. 1
, a portion of a tunnel or reheat furnace incorporating the present invention is illustrated and designated by the reference number
10
. The tunnel furnace
10
includes parallel spaced apart vertical refractory sidewalls
12
as well as top and bottom walls (not illustrated) which define an interior
14
through which a workpiece
16
passes. The workpiece
16
may be a bar, billet, strip, slab or other shape previously formed and provided to the tunnel furnace
10
at an elevated temperature. The vertical refractory side walls
12
define a plurality of pairs of aligned openings
18
which receive a plurality of roller assemblies
20
. A typical tunnel furnace
10
will contain between 54 and 128 roller assemblies
20
.
The roller assemblies
20
are supported for rotation at their ends upon pairs of pillow blocks
22
. At one end of each of the roller assemblies
20
is a drive assembly
24
which typically includes an electric motor
26
and a speed reduction assembly
28
which provides a reduced speed and increased torque drive to the associated roller assembly
20
. At the opposite end of each of the roller assemblies
20
is a rotary fluid coupling or union
30
which is stationary and includes relatively rotatable features which provide or inject a flow of cooling water at low temperature from a first pipe or conduit
32
into the roller assembly
20
and withdraw or extract this same flow of cooling water at an elevated temperature through a second pipe or conduit
34
. Preferably, relatively small rectangular or cylindrical plugs
38
in the sidewalls
12
of the tunnel furnace
10
which are removeably secured thereto by suitable fasteners (not illustrated) facilitate service and replacement of the roller assemblies
20
.
Disposed at intervals along the sidewalls
12
of the tunnel furnace
10
are gas-fired heaters
40
which provide jets of hot gas (not illustrated) through ports
42
in the sidewalls
12
which reheat the workpieces
16
as they pass through the tunnel furnace
10
. The size (BTU output) and number of the heaters
40
are such that they are capable of maintaining the interior
14
of the tunnel furnace
10
at temperatures in the range of 2000° F. (1095° C.) to 2300° F. (1260° C.).
Turning now to
FIGS. 2 and 3
, each of the plurality of roller assemblies
20
includes an elongate arbor or tubular shaft
46
which extends the full width of the tunnel furnace
10
and is supported for rotation in the pillow blocks
22
. The tubular shaft
46
is preferably fabricated of a low alloy steel. The tubular shaft
46
defines an annular passageway
48
which is also defined by a coaxially disposed tube or conduit
52
having an interior circular passageway
54
. Cooling water flows in one direction through the annular passageway
48
and in the opposite direction through the circular passageway
54
to remove heat from the roller assembly
20
according to conventional practice.
Cast directly on the outer surface of the arbor or tubular shaft
46
is a jacket or surround
56
of a high temperature, nickel alloy steel. Integrally cast with the jacket or surround
56
are a plurality of spaced apart, annular projections or wheels
58
. Typically, four to six wheels
58
are included on each roller assembly
20
although more or fewer may be utilized if desired or necessary. The annular projections or wheels
58
are separated by regions
60
of smaller diameter and include outer peripheral surfaces
62
and rounded (radiused) corners
64
which engage and support the workpiece
16
as it traverses the tunnel furnace
10
.
As illustrated in
FIG. 1
, it is preferable that the wheels
58
be disposed on adjacent roller assemblies
20
in staggered or offset patterns such that the longitudinal locations of support or contact with the workpiece
16
by the peripheral surfaces
62
of the wheels
58
do not define a plurality of constant paths but at least two offset pluralities of paths such that the likelihood of generating longitudinal tracks or marks in the workpiece
16
is minimized. By selecting an appropriate offset of each of the wheels
58
on a given roller assembly
20
from a reference point such as the longitudinal center of the roller assembly
20
, only a single roller assembly
20
configuration must be fabricated which improves manufacturing efficiency. An offset of 25% (one quarter) of the distance between adjacent wheels
58
of all the wheels
58
on the roller assemblies
20
is preferred and results in the wheels
58
being disposed in an evenly axially staggered pattern when every other roller assembly
20
is reversed end for end before it is installed in the tunnel furnace
10
. As illustrated in
FIG. 1
, the reference distance X represents the spacing between adjacent wheels
58
on one of the roller assemblies
20
. The distance Y is preferably X/2, i.e., one-half X, such that the wheels
58
on adjacent roller assemblies
20
are evenly and equally staggered or offset, as described above.
Preferably, the exterior surround
56
and the wheels
58
are cast of a high temperature, nickel steel alloy such as Waspaloy (also known as Carpenter Waspaloy), Inconel 100, Inconel 713. Inconel 718, MO-RE 2, 22H, Super 22H, Supertherm and metal alloys designated AISI 685. For purposes of disclosure, reference and in order to set forth the nominal parameters of metal alloys having the desired heat resistance, strength and serviceability, detailed descriptions of the foregoing metal alloys follow:
TABLE I
|
|
Material: Waspaloy
|
Manufacturer: United Technologies, Inc.
|
Chemical Composition:
Carbon
0.02-0.10 wt. %
|
Manganese
0.50 max.
|
Silicon
0.75 max.
|
Sulfur
0.020 max.
|
Chromium
18.0-21.0
|
Molybdenum
3.50-5.0
|
Cobalt
12.0-15.0
|
Titanium
2.6-3.25
|
Aluminum
1.0-1.50
|
Zirconium
0.02-0.12
|
Boron
0.003-0.008
|
Copper
0.10 max.
|
Iron
2.0 max.
|
Nickel
Balance
|
Material: Inconel 100
|
Manufacturer: The International Nickel Company, Inc.
|
Chemical Composition:
Carbon
0.15-0.20 wt. %
|
Chromium
8.00-11.00
|
Cobalt
13.00-17.00
|
Molybdenum
2.00-4.00
|
Titanium
4.50-5.00
|
Aluminum
5.00-6.00
|
Vanadium
0.70-1.20
|
Zirconium
0.03-0.09
|
Boron
0.01-0.02
|
Iron
1.00 max.
|
Manganese
0.20 max.
|
Silicon
0.20 max.
|
Sulfur
0.015 max.
|
Nickel
Balance
|
Material: Inconel 713C
|
Manufacturer: The International Nickel Company, Inc.
|
Chemical Composition:
Carbon
0.20 max. wt. %
|
Manganese
1.0 max.
|
Sulphur
0.015 max.
|
Silicon
1.0 max.
|
Chromium
11.0-14.0
|
Molybdenum
3.5-5.5
|
Titanium
0.25-1.25
|
Aluminum
5.5-6.5
|
Iron
5.0 max.
|
Columbium +
1.0-3.0
|
Tantalum
|
Nickel
Balance
|
Material: Inconel 718
|
Manufacturer: The International Nickel Company, Inc.
|
Chemical Composition:
Carbon
0.10 max. wt. %
|
Silicon
0.75 max.
|
Manganese
0.50 max.
|
Copper
0.75 max.
|
Nickel
50.0-55.0
|
Chromium
17.0-21.0
|
Columbium*
4.5-5.75
|
Molybdenum
2.8-3.3
|
Aluminum
0.2-1.0
|
Titanium
0.3-1.3
|
Iron
Balance
|
Material: MO-RE 2
|
Manufacturer: West Homestead Engineering Co.
|
Chemical Composition:
Nickel
48.00-52.00 wt. %
|
Carbon
0.15-0.25
|
Chromium
32.00-34.00
|
Manganese
0.30 max.
|
Silicon
0.30 max.
|
Tungsten
15.00-17.00
|
Molybdenum Al
0.75-1.25
|
Sulfur
0.04 max.
|
Phosphorus
0.04 max.
|
Material: 22-H
|
Manufacturer: West Homestead Engineering Co.
|
Chemical Composition:
Nickel
46.00-50.00 wt. %
|
Carbon
0.40-0.60
|
Chromium
26.00-30.00
|
Manganese
1.50 max.
|
Silicon
1.75 max.
|
Tungsten
4.00-6.00
|
Sulfur
0.04 max.
|
Phosphorus
0.04 max.
|
Material: Super 22-H
|
Manufacturer: West Homestead Engineering Co.
|
Chemical Composition:
Nickel
46.00-50.00 wt. %
|
Carbon
0.40-0.60
|
Chromium
26.00-30.00
|
Manganese
1.50 max.
|
Silicon
1.75 max.
|
Tungsten
4.00-6.00
|
Molybdenum
0.50 max.
|
Cobalt
2.50-4.00
|
Sulfur
0.04 max.
|
Phosphorus
0.04 max.
|
Material: Supertherm
|
Manufacturer: Abex Co.
|
Chemical Composition:
Carbon
0.50 wt. %
|
Manganese
0.70 max.
|
Silicon
1.60 max.
|
Chromium
26.0
|
Nickel
35.0
|
Cobalt
15.0
|
Tungsten
5.0
|
|
*Plus incidental tantalum
|
It will be appreciated that the foregoing delineation of suitable specific metal alloys is not intended to be exhaustive but is rather provided as a guide to present those compositions which are suitable and thus indicate nominal ranges of suitable constituents and compositions. It is anticipated that other alloys having compositions generally within the ranges taught above will also be suitable for use as described herein.
It will also be appreciated that a furnace roller assembly
20
according to the present invention provides improved service life because the unitary construction of the cast jacket or surround
56
and the wheels
58
minimizes thermal stresses caused by different thermal expansion rates which plagued many prior art roller designs assembled from multiple materials such as metal and ceramic.
The foregoing disclosure is the best mode devised by the inventor for practicing this invention. It is apparent, however, that apparatus and methods incorporating modifications and variations will be obvious to one skilled in the art of tunnel and reheat furnace rollers. Inasmuch as the foregoing disclosure presents the best mode contemplated by the inventor for carrying out the invention and is intended to enable any person skilled in the pertinent art to practice this invention, it should not be construed to be limited thereby but should be construed to include such aforementioned obvious variations and be limited only by the spirit and scope of the following claims.
Claims
- 1. A furnace roller assembly adapted to support a workpiece in a tunnel furnace comprising, in combination,a tubular support defining an exterior surface, an interior region and having a first, closed end and a second end, a tube disposed in said interior region and extending from said second end of said tubular support to proximate said first, closed end to provide co-axial coolant passageways, and a unitary, cast jacket of a high temperature, nickel steel alloy disposed about said exterior surface of said tubular support, said cast jacket including at least two spaced apart solid wheels and a reduced diameter intermediate, region between said wheels.
- 2. The furnace roller assembly of claim 1 further including a rotary fitting disposed at said second end of said tubular support, said fitting providing fluid communication with said tube.
- 3. The furnace roller assembly of claim 1 further including a rotary drive assembly coupled to said first, closed end of said tubular support.
- 4. The furnace roller assembly of claim 1 wherein said jacket includes at least four wheels and three of said intermediate regions.
- 5. The furnace roller assembly of claim 4 wherein said jacket and said wheels are a unitary casting.
- 6. The furnace roller assembly of claim 1 further including a union at one end of said tubular support for coupling water supply lines to said roller assembly.
- 7. A furnace roller assembly adapted to support a workpiece in a tunnel furnace comprising, in combination,an elongate tubular shaft defining an exterior surface, an interior space, a closed end and an open end, and a unitary, cast metal jacket of high temperature, nickel steel alloy disposed about said exterior surface of said tubular shaft, said jacket including a plurality of spaced apart larger diameter regions and a plurality of reduced diameter regions between said larger solid diameter regions.
- 8. The furnace roller assembly of claim 7 further including a rotary drive assembly coupled to one end of said tubular support.
- 9. The furnace roller assembly of claim 7 further including an elongate tube disposed in said interior space of said elongate tubular shaft and having a first open end adjacent said open end of said tubular shaft and a second open end proximate said closed end of said tubular shaft.
- 10. The furnace roller assembly of claim 7 further including a union at one end of said tubular support for coupling at least one fluid supply line to said roller assembly.
- 11. The furnace roller assembly of claim 7 further including a second furnace roller assembly disposed adjacent said furnace roller assembly and wherein said larger diameter region of said roller assemblies are disposed in staggered relationship.
- 12. A furnace roller assembly adapted to support a workpiece in a tunnel furnace comprising, in combination,a tubular support defining an exterior surface, an interior region, a first, closed end and a second end having a rotary fitting providing fluid communication with said interior region, a tube disposed within said interior region and having a first open end proximate said first, closed end of said tubular support and a second end in fluid communication with said rotary fitting, and a metal surround of high temperature steel nickel alloy disposed about the said exterior surface of said tubular support, said surround including regions of larger diameter alternating with regions of reduced diameter.
- 13. The furnace roller assembly of claim 12 wherein said surround is cast of Waspaloy.
- 14. The furnace roller assembly of claim 12 further including a rotary drive assembly coupled to said closed end of said tubular support.
- 15. The furnace roller assembly of claim 12 wherein said rotary fitting includes a union at one end of said tubular support for coupling at least one fluid supply line to said roller assembly.
- 16. The furnace roller assembly of claim 12 wherein said furnace roller assembly is installed in a furnace having a plurality of gas heaters.
US Referenced Citations (5)