Furnace roller and cast tire therefor

Information

  • Patent Grant
  • 6435867
  • Patent Number
    6,435,867
  • Date Filed
    Friday, November 10, 2000
    24 years ago
  • Date Issued
    Tuesday, August 20, 2002
    22 years ago
Abstract
There is provided a cast tire for use with a furnace roller. The cast tire has at least three of annular spaced pockets located around the central opening of the tire on each radial side. When the tires are installed on a furnace roller with arbor means, pockets are inserted into the annular spaced pockets. The pockets are secured only to the arbor means of the roller. Rotation of the arbor means results in rotation of the cast tires by transmission of torque from the pockets to the to the tire without direct attachment of the tire to the arbor means.
Description




CROSS-REFERENCE TO RELATED APPLICATIONS




Not applicable.




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to an improved furnace roller to advance a metallic workpiece through a reheat furnace and more particularly to a tire construction and securement structure for mounting the tire to an arbor which includes the provision of a core buster for cooling of the arbor.




2. Description of Related Art




Furnace rollers are used to support and guide metallic workpieces through a furnace. U.S. Pat. No. 4,991,276 discloses of one type of furnace roller that is applicable to the present invention. The furnace roller includes a plurality of wheel members welded at spaced apart locations along to an outer tubular member used to form the arbor. The wheel member includes inner hub sections formed of a plurality of angularly spaced-based members. Each base member has a toe portion and head portion separated by a gap extending in the direction of the arbor. A short length of weld at the lateral side of each toe portion interconnects the toe portion to the outer tubular member. The head portion is unattached and free to slide relative to the outer tubular member of the arbor in response to the effect of differential expansion caused by a relatively large thermal gradient in the roller and the bending effect by the weight of the strip upon the roller. A web portion extends from each base member. Each web portion is angularly separated from an adjacent web section by an elongated open space that projects outward slightly short of the inner radius of the rim. The open space further serves to reduce and impede heat flow to the arbor by way of the base member. Apertures are provided in the web portion to provide passage for metal rods used to secure a complement of thermally-insulating discs between the wheel members and thereby provide thermal protection from the high temperature environment in the furnace.




A different furnace roller construction uses castable refracting to form the insulation barrier between wheels is initially covered with a thermal resistant insulating material as disclosed in U.S. Pat. No. 5,230,618. When the roller is used in furnaces operating at approximately 2000° F. or higher, the insulating material can be damaged and separate from the roller in the vicinity of a tire the edge by a terminal or leading edge of a strip. Exposure of the tire's radial sides to the furnace operating temperatures causes thermally induced metal fractures to occur between the open spaces and apertures in the wheel hub. When multiple fractures between the open spaces and apertures the fractures lead to the separation of the rim from its hub.




Research into the causes of the metal fracture led to the apertures and constructing the head portions of the base members flush with the hub. With furnaces operating at temperatures above 2100° F., this design results in occasional fracturing across the tire's rim without protective insulating material. One particular thermal study of this furnace roller in a 2100° F. atmosphere with the toe portion of the base member welded to a water-cooled shaft revealed the following conditions. The rim temperature was 2026° F. with a radial displacement of the rim equal to 0.1228-inch on its radius. The temperature of the toe portion at the weld connection to a watered-cooled shaft was 400° F., with a displacement of 0.008-inch and a bending stress in the base member of 76,212 psi. With this configuration, the 400° F. base members restrain the wheel rim from expanding. This phenomenon accounts for the rim fractures observed in actual furnace operations. An advantage exists, therefore, for a tire that will permit the rim to expand to prevent rim fractures from occurring when operating in an environment with temperatures above 2000° F. The use of weld metal to establish a metal-to-metal connection between the wheels and the arbor of a furnace roller when eliminated will permit the wheel's rim to expand when operating in the extreme temperature environment to which reference has been made.




It is therefore an object of the present invention to provide an improved tire that eliminates the base member with direct toe connection of the tire to the shaft of the furnace roll and allows the rim of the tire to expand to prevent fractures from occurring when operating in the extreme temperature environment to which reference has been made.




It is another object of the present invention to provide improved furnace rollers using the improved tires of the present invention that will allow operation of the rollers in the extreme temperature environment to which reference has been made for long periods of operating times without fracturing of the tires.




BRIEF SUMMARY OF THE INVENTION




More particularly according to the present invention there is provided a cast tire for use in a furnace roller to support and advance a workpiece in a furnace, the cast tire including, a rim portion having an annular peripheral tire face to engage and support a workpiece during conveyance thereof in a heated chamber of a furnace, and a continuous web portion having an inner most annular surface contiguous with the outer rim portion, the inner most annular surface defining a load-bearing seat for load-bearing support by an axle, the continuous web having oppositely directed radial face surfaces forming boundaries of angularly spaced pockets bounded by radial edges generally perpendicular to the inner most annular surface, the radial edges being elongated to form moment arms to transmit torque from an applied force by an axle to rotate the continuous web and the rim portion for conveying a workpiece.




The present invention further provides a furnace roller for supporting a workpiece in a furnace, the furnace roller including a rotatable arbor, a number of tires having substantially equal radial extending rim portions at axially spaced apart sites along the arbor for engaging a workpiece, each tire further comprising a continuous web portion having an inner most annular surface contiguous with the outer rim portion, the inner most annular surface defining a load-bearing seat for load-bearing support by an axle, the continuous web having oppositely directed radial face surfaces forming boundaries of angularly spaced pockets bounded by radial edges generally perpendicular to the inner most annular surface, the radial edges being elongated to form moment arms to transmit torque from an applied force by an axle to rotate the continuous web and the rim portion for conveying a workpiece, a plurality of anchor members seated in the pockets and drivingly secured to the arbor for rotation by the arbor; and thermal insulation supported by the arbor to provide a thermal barrier to extend radially between the tires, the insulation having a thickness terminating with an outer surface extending radially at least a substantial portion but less than the entire radii of the tires.











BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS




For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.





FIG. 1

is a plan view of a radial side of the tire of the present invention;





FIG. 2

is a sectional view taken along lines A—A of

FIG. 1

;





FIG. 3A

is a plan view of the pocket used with the tire of the present invention;





FIG. 3B

is a sectional view taken along lines B—B of

FIG. 3A

;





FIG. 4

is a cross sectional view of the tire of the present invention installed on the arbor of a furnace roller;





FIG. 5

is an elevational view illustrating the furnace roller of the present invention in its operative state forming part of a tunnel furnace;





FIG. 6

is an elevational view partly in section illustrating spaced apart tires on an arbor for the furnace roller of

FIG. 5

;





FIG. 7

is a sectional view illustrating final assembly of the furnace roller assembly depicted in

FIG. 5

;





FIG. 8

is a sectional view taken along lines VIII—VIII of

FIG. 7

; and





FIG. 9

illustrates an elongated core buster forming part of the furnace roller shown in FIG.


5


.











DETAILED DESCRIPTION OF THE INVENTION




A furnace roller of the present invention embodies a novel design for a cast wheel or tire shown in

FIG. 1 and 2

. The tire


10


is cast from a thermally dimensionally stable and heat-resistant metal material such as a high temperature nickel-chrome alloy or cobalt-chrome alloy, or the like, to minimize thermal effects of operating in a high temperature environment at temperatures above 2000° F. The tire


10


includes an enlarged outer rim portion


15


providing an annular peripheral tire face surface


17


for engaging and supporting a metal workpiece such as a strip during conveyance of the workpiece in the heating chamber of a furnace particularly a tunnel furnace.




The cast tire


10


essentially also includes a thinner, as compared to the thickness of rim portion


15


as shown in

FIG. 2

, a continuous web portion


20


continuous with the rim portion


15


. The continuous web portion


20


has an inner most annular surface


22


appearing as a central opening and a load-bearing seat for load-bearing support by an axle, preferably an arbor with the tire forming one of a number of such tires on an arbor as part of a furnace roller, as will be described in greater detail hereinafter. The continuous web


20


is further defined by oppositely directed radial face surfaces


24


and


26


each containing angularly spaced pockets


30


bounded by radial edges


31


generally perpendicular to the inner most end annular surface


22


. The radial edges


31


of each pocket are elongated to form moment arms to develop torque from an applied force to an axle to rotate the continuous web portion


20


and thereby also the rim portion


15


for conveying a workpiece. The pockets


30


are used to seat anchor members


40


as further described below. The pockets


30


are axially spaced around the annular surface


22


on each radial side of the hub portion


20


. In the preferred embodiment, all pockets


30


are substantially equal in size and the axial spacing between all adjacent pockets on each radial side of the hub portion are equal. Furthermore, in the preferred embodiment, pockets on the opposing sides of the hub portion


20


are axially offset by a spacing substantially equal to half the axial spacing between adjacent pockets. The pockets


30


for the opposing side of the cast tire


10


are shown in phantom in FIG.


1


. In the preferred embodiment shown in

FIGS. 1 and 2

with three pockets on each of the two sides of the tire, the slots are spaced apart by 120 degrees and radially offset from each other by 60 degrees. Each pocket


30


has an arcuate top surface


32


between the radial edges


31


.




As shown in

FIGS. 3A and 3B

, an anchor member


40


, preferably of the same material as the cast tire


10


, has the form defining a circular ring sector with inner surface


42


and outer boundary surface


41


defined by radii one of which conforms to the radius of the outside diameter of an arbor used to support the tire and the other radius of outer boundary surface


41


conforms to the radius of the arcuate top surface


32


of pocket


30


. The arcuate bottom surface


42


of the anchor member substantially conforms to the curvature of the radial surface defining the central opening of the hub portion of the tire. The rear top edge


48


of the anchor member is beveled to properly seat against the radial edges


31


of the pocket. The radial face surfaces forming boundaries of the angularly spaced pockets have their radial edges elongated to form moment arms to transmit torque from an applied force by the axial to rotate the tire and thus also the furnace roller. The front bottom edge


47


of the anchor member is beveled to accommodate the composite zone of a weld as further described below. Opposing end surfaces


46


of the anchor member are flat and join top surface


41


in an arcuate surface conforming to the shape of the pocket


30


. The anchor member's opposing front and back sides


43


and


44


, respectively are substantially flat. The overall dimensions of an anchor member


40


are such that it conforms to fill the space defined by pocket


30


with the following exceptions. As best shown in

FIG. 4

, the overall width of the anchor member


40


from front side


43


to back side


44


is longer in width than the depth of the pocket


30


and substantially equal to the width of the rim portion


15


of the tire. Additionally, a clearance gap


59


exists between the top surface


32


and rounded inner edge


34


of the pocket


30


, and the outer boundary surface


41


and rear top edge


48


of the anchor member


40


.




The cast tire


10


of the present invention can be used with a furnace roller


50


shown in

FIG. 5

includes a plurality of spaced apart workpiece supporting tires


10


.

FIG. 4

illustrates a tire


10


supported by an outer tubular surface of an arbor


58


also forming part of the furnace roller. The anchor member


40


is inserted into each pocket


30


on the tires. The anchor members


40


are welded to the outer tubular surface of an arbor


58


. The composition zone of the weld


60


is substantially disposed within the beveled lower bottom edge of each anchor member


40


. The anchor members


40


will keep the tires


10


in alignment (at 90 degrees to the axis of the arbor) and transmit the required torque from the rotating arbor primarily by the contact of the ends


46


of the anchor members


40


with the corresponding radial edges


31


to propel the strip product though the furnace. The width of the anchor member within the pocket, and consequently the depth of the pocket, is primarily determined by the magnitude of the required torque transmission. A design safety factor may be added to the depth of the pocket.




A spacing material


62


, such as masking tape, can be placed between the back side


44


of the anchor member and the inner radial surface of the pocket


30


. The spacing material


62


provides clearance between the surface of the pocket and rear surface of the anchor member


40


to allow for thermal expansion of the width of the tire


10


between the anchor members


40


that are welded to the arbor


58


and located on the opposing radial sides of the tire. Upon reaching operating temperature, the spacing material


62


will compress or burn off.




As shown in

FIGS. 5 and 6

, four tires


10


are installed at spaced apart locations along the arbor


58


in the manner as just described. After installation of the cast tires


10


on the arbor


58


as shown in

FIGS. 7 and 8

, a body of castable insulation


64


separated by spacers from the arbor and the side wall of the tires is formed at each of the three locations between the tires. Additionally, a body of insulation


66


separated by spacers from the arbor and the side wall of the tires is formed along each of the terminal end portions of the arbor. In a manner known per se, anchors


68


affixed to the arbor along the length thereof serve to hold the castable insulation on the arbor. As shown in

FIG. 5

, the castable insulation and tires therebetween are located in a furnace between spaced apart furnace side walls


70


which are provided with apertures to allow arbor shaft extensions


72


A and


72


B to extend to support bearings


74


and


76


are mounted on pedestals


78


and


80


. Outwardly of bearing


76


, pedestal


80


supports a motor


82


connected by a coupling


84


to arbor shaft extensions


72


B. Outwardly of bearing


74


, the terminal end portion of arbor shaft is provided with a rotary coupling


86


for the supply and delivery of coolant water. The rotary coupling communicates with the internal cavity in a core buster segment


90


. Spacers


92


projecting from the outer surface of the core buster segment at spaced locations along the length thereof, form a flow channel for coolant water emerging from a passageway


94


. This passageway is elongated to take the form of a notch, the terminal end portion of which drivenly engages with a key


96


projecting from the inner face of arbor shaft extensions


72


B. Arbor shaft extensions


72


A has an internal threaded end portion


72


C to receive a threaded end plug which abuts against lugs


98


on the core buster for retaining the core buster in seated engagement within the internal cavity of the arbor


58


.




In one particular embodiment when a water-cooled furnace roller is exposed to a 2200° F. atmosphere, the tire temperature at the outer tubular member


58


of the arbor is approximately 1400° F., whereas the anchor members


40


are at a temperature of approximately 730° F. The thickness of the spacing material


90


compensates for the thermal expansion difference between the width of the 1400° F. tire and the 730° F. anchor member welded to the outer tubular member


58


of the arbor. Thus, a furnace roller using the cast tires


10


of the present invention results in a significant increase in thermal resistance between the tire and the outer tubular member of the arbor.




The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. Accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.



Claims
  • 1. A cast tire for use in a furnace roller to support and advance a workpiece in a furnace, said cast tire including:an outer rim portion having an annular peripheral tire face to engage and support a workpiece during conveyance thereof in a heated chamber of a furnace; and a continuous web portion having an inner most annular surface contiguous with said outer rim portion, said inner most annular surface defining a load-bearing seat for load-bearing support by an axle, said continuous web portion having oppositely directed radial face surfaces forming boundaries of angularly spaced pockets bounded by radial edges generally perpendicular to said inner most annular surface, said radial edges being elongated to form moment arms to transmit torque from an applied force by an axle to rotate said continuous web portion and said outer rim portion for conveying a workpiece.
  • 2. The cast tire according to claim 1 wherein said continuous web portion is impervious to fluid flow to maintain a substantially constant temperate gradient radially from said load-bearing seat to said rim portion.
  • 3. The cast fire according to claim 1 wherein said angularly spaced pockets comprise circular ring sector segments.
  • 4. The cast tire according to claim 3 wherein said circular ring sector segments intersect said inner most annular surface.
  • 5. The cast tire of claim 4 wherein said angularly spaced pockets in a first side of said continuous web portion are axially offset from the angularly spaced pockets on the second radial side by a spacing substantially equal to half the axial spacing between adjacent angularly spaced pockets.
  • 6. The cast tire of claim 1 wherein the number of angularly spaced pockets in a first radial side of said continuous web portion is equal to the number of angularly spaced pockets in a second and opposite radial side of said continuous web.
  • 7. The cast tire of claim 6 wherein the angularly spacing between angularly spaced pockets on each radial side is substantially equally.
  • 8. The cast tire of claim 7 wherein the angularly spaced pockets on the first radial side are axially offset from the angularly spaced pockets on the second radial side by a spacing substantially equal to half the axial spacing between adjacent angularly spaced pockets.
  • 9. The cast tire of claim 1 wherein said rim portion is a thickened enlargement to said continuous web portion.
  • 10. The cast tire according to claim 1 wherein said angularly spaced pockets comprise discrete pockets disposed about a side face of said continuous web portion.
  • 11. The cast tire according to claim 10 wherein the number of angularly space pockets in each of oppositely directed side face surfaces of said continuous web portion is equal.
  • 12. The cast tire according to claim 1 wherein said angularly spaced pockets comprise at least three annular spaced pockets axially disposed around said inner most annular surface on each radial side of said continuous web portion.
  • 13. The cast tire according to claim 12 wherein the angular spacing between adjacent pockets equals 120 degrees and the pockets on opposing radial sides of said continuous web portion are offset by 60 degrees.
  • 14. A furnace roller for supporting a workpiece in a furnace, the furnace roller including:a rotatable arbor; a number of tires having substantially equal radial extending outer rim portions at axially spaced apart sites along said arbor for engaging a workpiece, each tire further comprising a continuous web portion having an inner most annular surface contiguous with said outer rim portion thereof, said inner most annular surface defining a load bearing seat for load bearing support by an axle, said continuous web portion having oppositely directed radial face surfaces forming boundaries of angularly spaced pockets bounded by radial edges generally perpendicular to said inner most annular surface, said radial edges being elongated to form moment arms to transmit torque from an applied force by an axle to rotate said continuous web portion and said outer rim portion for conveying a workpiece; a plurality of anchor members seated in said pockets and drivingly secured to said arbor for rotation by the arbor; and thermal insulation supported by said arbor to provide a thermal barrier to extend radially between the tires, the insulation having a thickness terminating with an outer surface extending radially at least a substantial portion but less than the entire radii of the tires.
  • 15. A furnace roller according to claim 14 wherein said anchor members define circular ring sectors having inner and outer boundaries surfaces defined by radii one of which conforms to a radius of the outside diameter of said arbor and the other conforms to a radial boundary of said pockets.
  • 16. A furnace roller according to claim 15 further including weld metal to secure each anchor member essentially only to said arbor.
  • 17. A furnace roller according to claim 14 wherein said arbor is further defined as a first pipe having a cylindrical internal cavity with a barrier wall at one end of the pipe to block the flow of fluid beyond the barrier wall and a passageway for fluid at the opposite end of the pipe, a core buster segment disposed within said first pipe to form a substantially annular first region between the inner surface of said first pipe and the outer surface of said core buster segment, said core buster segment having a fluid passageway at one end thereof for fluid flow between the inner passageway of core buster segment and the outer surface thereof whereby a continuous flow path for fluid is provided between the inner and outer surfaces of said core buster.
  • 18. A furnace roller according to claim 14 wherein said continuous web portion is impervious to fluid flow to maintain a substantially constant temperature gradient radially from said load bearing seat to said rim portion.
  • 19. The furnace roller according to claim 14 wherein said angularly spaced pockets comprise circular ring sector segments.
  • 20. The furnace roller according to claim 19 wherein said circular ring sector segments intersect said inner most annular surface.
  • 21. The furnace roller of claim 20 wherein said angularly spaced pockets in a first side of said container web portion are axially offset from the angularly spaced pockets on the second radial side by a spacing substantially equal to half the axial spacing between adjacent angularly spaced pockets.
  • 22. The furnace roller of claim 14 wherein the number of angularly spaced pockets in a first radial side of said continuous web portion is equal to the number of angularly spaced pockets in a second and opposite radial side of said continuous web portion.
  • 23. The furnace roller of claim 22 wherein the angularly spacing between angularly spaced pockets on each radial side is substantially equally.
  • 24. The furnace roller of claim 23 wherein the angularly spaced pockets on the first radial side are axially offset from the angularly spaced pockets on the second radial side by a spacing substantially equal to half the axial spacing between adjacent angularly spaced pockets.
  • 25. The furnace roller of claim 14 wherein said rim portion is a thickened enlargement to said continuous web portion.
  • 26. The furnace roller according to claim 14 wherein said angularly spaced pockets comprise discrete pockets disposed about a side face of said continuous web portion.
  • 27. The furnace roller according to claim 26 wherein the number of angularly space pockets in each of oppositely directed side face surfaces of said continuous web is equal.
US Referenced Citations (4)
Number Name Date Kind
4991276 Bricmont Feb 1991 A
5145277 Fujita et al. Sep 1992 A
5230618 Bricmont et al. Jul 1993 A
5341568 Bricmont et al. Aug 1994 A