The present invention relates to a roller assembly used in a furnace to move metal product through the furnace by rotating the roller assembly so that metal product sitting on the roller assembly advances through the furnace.
A furnace roller assembly, or furnace roll or roller, is used to move a metal product through a furnace. Typically the metal product is a flat sheet, or slab, that travels along the length of the furnace by making surface contact with structural elements attached to each furnace roller assembly installed along the length of the furnace. U.S. Pat. No. 5,833,455 relates various types of furnaces, including roller hearth tunnel furnaces, and the metal products moving through the furnaces in the description of the prior art. The furnace roller assembly rotates by connection to a suitable drive that may include a motor, and is typically cooled by internal water flow.
The radially outward surface of the rim of a metallic tire is typically used in a furnace roller as the structural element making friction contact with metal product, as shown for example, in U.S. Pat. Nos. 5,230,618 and 5,341,568 where multiple tires are spaced apart from each other along the arbor, or shaft, of the furnace roller. In these arrangements the shaft is oriented perpendicular to the direction of the metal product moving through the furnace, and the radially outward surfaces of the rims are parallel to the direction of the moving metal product.
As mentioned in the description of related art in U.S. Pat. No. 6,435,867 B1, the structural interface between a tire and the arbor (or shaft) of the furnace roller is critical to designing a furnace tire that will withstand the harsh furnace operating environment. Furnace tire life is a function of temperature of the metal product passing over the rim of the tire; metal product heating may be limited based upon the requirement to maintain a minimum service life for each installed tire. Further tire tracking, or skid marks, can result on the metal product from the fixed position of each tire's rim relative to the length of the metal product as it passes through the furnace. Depending upon the use of the product leaving the furnace, further processing of the product may be required to remove the tire tracking.
One objective of the present invention is to provide a method of moving metal product through a tunnel roller furnace with fewer limitations on the maximum temperature of the product based upon furnace roller life.
Another objective of the present invention is to provide a furnace roller that will not leave tire tracks, or other blemishes, on the product as it passes through the furnace.
In one aspect the present invention is a furnace roller assembly and method of constructing a furnace roller assembly. The roller assembly is provided with a helically shaped shaft-offset and metal product contact surface assembly wound around a hollow shaft that can have an interior corebuster to provide a cooling medium flow path through the shaft and a cooling element forming a part of the shaft-offset and metal product contact surface assembly.
In another aspect the present invention is a furnace roller assembly comprising a shaft-offset and metal product contact surface assembly helically wound around the outer surface of a furnace roller shaft along the axial length of the furnace roller shaft. The shaft-offset and metal product contact surface assembly comprises: a wear element that is radially offset from the outer surface of the furnace roller shaft; a cooling element that is connected to the wear element; and a support element that is connected between the outer surface of the furnace roller shaft and the cooling element. The cooling element has an internal coolant passage that terminates at the cooling element's opposing ends at shaft supply and return coolant openings located along the axial length of the outer surface of the furnace roller shaft. The helically wound shaft-offset and metal product contact surface assembly may be counter wound about a central location on the outer surface of the furnace roller shaft towards the opposing axial ends of the furnace roller shaft. A drive, or other rotational means, can be attached to an end of the furnace roller shaft to rotate the furnace roller shaft and the helically wound shaft-offset and metal product contact surface assembly. In some examples of the invention, more than one shaft-offset and metal product contact surface assembly may be provided along the outer surface of the furnace roller shaft.
In some examples of the invention, the support element may be an elongated planar support plate having first and second opposing planar edges along the length of the support plate where the plane of the support plate extends radially from the outer surface of the furnace roller shaft. The first edge of the support plate may be continuously connected to the outer surface of the furnace roller shaft, and the second edge of the support plate may be continuously connected to the cooling element, which may be a tubular element. The wear element may be a planar wear bar that is connected to the cooling element so that a planar surface of the wear bar is radially offset from the outer surface of the furnace roller bar. In some examples of the invention, the support element may be an elongated V-shaped angle element with the ends of the extended legs of the V-shaped angle element connected to the outer surface of the furnace roller shaft, and with the joined ends of the V-shaped angled element connected to the cooling element. In some examples of the invention, the support element, cooling element and wear element may be integrally cast. In some examples of the invention the cooling element and wear element may be integrally formed. In some examples of the invention a thermal insulation is deposited over at least a portion of the outer surface of the furnace roller shaft.
In some examples of the invention, a corebuster is located within the furnace roller shaft and radially positioned relative to the interior surface of the furnace roller shaft to form a generally annular inter-volume between the outer surface of the corebuster and the inner surface of the furnace roller shaft. A continuous coolant flow can be formed through the shaft and corebuster. In some examples of the invention the continuous coolant path can be formed with a continuous coolant supply passage along the axial length of the furnace roller shaft in a first axial direction in communication with a continuous coolant return passage along the axial length of the furnace roller shaft in a second axial direction opposite the first axial direction. The shaft coolant inlet and outlet are located at the first axial end of the furnace roller shaft. The continuous coolant supply passage along the axial length of the furnace roller shaft in the first axial direction is formed from three segments. The first coolant supply passage segment is located within the interior of the corebuster and extends from the shaft coolant inlet to a first transition located radially adjacent to the offset assembly return coolant opening on the shaft, but is isolated from the offset assembly return coolant opening. The second coolant supply passage segment is located within the annular inter-volume extending from the first transition to a second transition located radially adjacent to the offset assembly supply coolant opening on the shaft, but is isolated from the offset assembly supply coolant opening. The third coolant supply passage segment is located within the interior of the corebuster extending from the second transition to the axial end of the furnace roller shaft opposing the first axial end of the furnace roller shaft. The continuous coolant return passage along the axial length of the furnace roller shaft in the second axial direction is formed from three segments. The first coolant return passage segment is located within the annular inter-volume and extends from the axial end of the furnace roller shaft opposing the first axial end of the furnace roller shaft to the offset assembly supply coolant opening. The second coolant return passage segment is within the cooling element and extends from the cooling element supply end to the cooling element return end. The third coolant return passage segment is within the annular inter-volume and extends from the offset assembly return coolant opening to the shaft coolant outlet.
In another aspect the present invention is a method of fabricating a furnace roller assembly. A linearly oriented elongated shaft-offset and metal contact surface assembly is fabricated from a wear, cooling and support element. The support element is connected to the cooling element, and the cooling element has an internal coolant passage terminating at opposing cooling element supply and return ends. Offset assembly supply and return coolant openings are formed along the length of a furnace roller shaft. The first ends of an offset assembly supply and return transition fittings are respectively connected to the offset assembly supply and return coolant openings. The linearly oriented shaft-offset and metal contact surface assembly is helically bended around the outer surface of the furnace roller shaft and the support element is connected to the outer surface of the furnace roller shaft. The second ends of the offset assembly supply and return transition fitting are respectively connected to the cooling element supply and return ends.
In another aspect, the present invention is a method of moving a metal product through a furnace. The axial lengths of at least two furnace roller assemblies are arranged in a furnace perpendicular to the direction of moving the metal product through the furnace. At least one of the two furnace roller assemblies comprises a furnace roller shaft and at least one shaft-offset and metal product contact surface assembly helically wound around the outer surface of the furnace roller shaft along the axial length of the furnace roller shaft. The at least one shaft-offset and metal product contact surface assembly comprises a wear element, a cooling element and a support element. The cooling element is connected to the wear element. The cooling element has an internal coolant passage terminating at opposing cooling element supply and return ends at an offset assembly supply and return coolant openings, respectively, located along the length of the furnace roller shaft. The support element is connected between the outer surface of the furnace roller shaft and the cooling element to radially offset the cooling element and wear element from the outer surface of the furnace roller shaft. Both of the at least two furnace roller assemblies are rotated to move the metal product over the at least two furnace roller assemblies in the furnace.
The above and other aspects of the invention are set forth in this specification and the appended claims.
The foregoing brief summary, as well as the following detailed description of the invention, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings exemplary forms of the invention that are presently preferred; however, the invention is not limited to the specific arrangements and instrumentalities disclosed in the following appended drawings.
a),
a) is a partial cross sectional elevation view along the longitudinal axis L-L of the furnace roller assembly shown in
b) is a partial cross sectional elevation view along the longitudinal axis of the furnace roller assembly shown in
There is shown in
As shown in
Depending upon the particular application, support element 18a may not be a continuous plate along the entire length of the cooling tube; for example it may be formed as an open spoke structure. Alternatively the plate may also be similar to an inverted “V” shaped element 18c as shown in
Alternatively the cooling and wear element may be combined into a single structural element such as rectangular pipe 24 in
The linear shaft-offset and metal product contact surface assembly 16 can be formed helically around the outer diameter of shaft 14 as shown in
Preferably, but not by way of limitation, the shaft-offset and metal product contact surface assembly is helically counter-wound about a central location C-C along its axial length for approximately each half axial length of the shaft within the furnace as shown in
In alternative examples of the invention, adjacent furnace roller assemblies may each have an offset assembly that is helically wound continuously in one direction for the entire axial length of the shaft, but helically counter-wound to each other (that is, one furnace roller assembly has a right-handed helix offset assembly and the adjacent roller has a left-handed helix offset assembly), to eliminate the damage mentioned above when multiple adjacent furnace roller assemblies are continuously wound with the same helical orientation.
While the width of the metal product, or slab, can vary with conventional furnace rollers having in-line tires as described above in the background of the invention, the product width must be of discrete widths so as to avoid product widths with edges near a furnace tire on the roller. With the helical wear bars utilized in the present invention, the metal product can be of any width above a minimum width generally defined by the pitch of the helix in a particular application since the support points (wear bar helical outer surface) are constantly changing. As noted in
The interior passage of each end of the helical cooling element 20 can be connected to the interior of the furnace roller's shaft for circulation of a coolant, such as water, through the cooling element. Coolant supply and return can be made at one end of the furnace roller's shaft through a duo flow rotary union. In one example of the invention, the coolant supply is introduced into the furnace roller assembly at one end of the shaft through a corebuster disposed within the shaft, which transmits the coolant to the opposing axial end of the furnace roller's shaft. A barrier plate in the corebuster diverts the return flow of the coolant to the interior volume between the inner diameter of the furnace roller's shaft and the outer diameter of the corebuster, and then exits through the rotary union.
While a single continuous shaft-offset and metal product contact surface assembly is helically wound around the outer surface of the shaft in the above examples of the invention, in other examples of the invention, two or more separate shaft-offset and metal product contact surface assemblies may be used.
In some examples of the invention, thermal insulation 40, for example a refractory, can optionally be provided at least around the outer surface of shaft 14 to minimize furnace heat loss to the relatively low temperature shaft as shown in
The above examples of the invention have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the invention has been described with reference to various embodiments, the words used herein are words of description and illustration, rather than words of limitations. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein; rather, the invention extends to all functionally equivalent structures, methods and uses. Those skilled in the art, having the benefit of the teachings of this specification, may effect numerous modifications thereto, and changes may be made without departing from the scope of the invention in its aspects.
This application claims the benefit of U.S. Provisional Application No. 61/160,806, filed Mar. 17, 2009, hereby incorporated by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
61160806 | Mar 2009 | US |