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&#39;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&#39;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&#39;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&#39;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.