Abstract:
A method for forming shingles from cellular polyvinyl chloride boards comprising brushing, parting, cutting and coating the boards to desired dimensions and finish. The method comprises passing cellular polyvinyl chloride boards through one or more of a specially designed brushing assembly, cross cut saw assembly, parting assembly, and sizing saw assembly, wherein the assemblies are in-line. The method may further include an in-line, high speed application and accelerated curing of a uniquely formulated solar reflective, ceramic-based finish.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/326,720 filed on Apr. 22, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally directed to a process for preparing a shingle material. More particularly, the present invention relates to a process for preparing cellular polyvinyl chloride materials for use as shingles to mimic traditional, Western red cedar shingles. 
     2. Background of the Invention 
     Traditionally, side and roof shingles are made from Western red cedar or Eastern white cedar. In recent years, fiber cement and a variety of polymers have been pressed and/or injection molded to simulate the look of these wood standards. Each of these materials, however, has certain inherent problems that make them less than ideal from a building perspective. 
     For example, shingles made from cedar tends to absorb moisture, and to, consequently, warp, decay, and rot. Additionally, insects are attracted to the wood, and, therefore, contribute to the decay. Furthermore, when painted, the paint tends to blister, peel, and crack. 
     Although it absorbs less water than wood siding materials, fiber cement shingles do absorb some moisture if not carefully installed and maintained. To reduce the moisture and paint problems, the cut edges of the fiber cement shingles must be carefully treated. Furthermore, fiber cement shingles are flat (not beveled), unduly heavy, brittle, require specialized tools and instruments for installation, and debris formed during its installation may create health risks. For these reasons, then, fiber cement shingles are difficult to install and maintain, and because they are flat and uniform in appearance, they are not a close aesthetic match to wood shingles. 
     Molded polymer shingles and shingle panels improve upon the use of wood and fiber cement in that they are less subject to water related maintenance issues. However, molded shingles are very light and hollow giving them a less authentic appearance and feel. Additionally, molded shingles and panels must be overlapped to accommodate expansion and contraction. As a result, a tell-tale sign of molded polymer versus cedar and fiber cement shingles is the overlapping joints and repeating patterns that appear on most molded polymer installations. Also, molded shingles must be inserted into j-channel trim installed around windows, doors and at all corners in order to accommodate expansion and contraction of the polymer with changes in temperature. Further, molded polymer shingles and shingle panels have tended to discolor over time; thereby diminishing their perceived value considerably. 
     BRIEF SUMMARY OF THE INVENTION 
     The above-discussed drawbacks and deficiencies of the prior art are greatly reduced or eliminated by a novel in-line process and apparatus for preparing novel cellular polyvinyl chloride (“cellular PVC”) shingles, wherein the process utilizes novel material removal, product handling, and finishing techniques. 
     An improved product for use as shingles and shingle panels is milled from cellular PVC sheet stock. Similar to molded polymer products, cellular PVC shingles expand and contract with changes in temperature, but when installed as individual shingles, this rate of expansion and contraction is negligible allowing contractors to install this product in the same manner that they have used for cedar shingles for centuries. Cellular PVC shingles and shingle panels can be finished with solar reflective, ceramic-based coatings that minimize fade and optimize performance (no cracking, peeling or blistering). Very importantly, research by the Department of Energy demonstrates that such coatings, when used on cellular PVC, can produce annual HVAC savings of 5-9%, depending upon the location in North America. 
     The inventive process comprises passing cellular PVC boards/bolts through one or more of a specially designed brushing assembly, cross cut saw assembly, parting assembly, and sizing saw assembly. The inventive process further incorporates an in-line, high speed application and accelerated curing of a uniquely formulated solar reflective, ceramic-based finish. Accordingly, the invention relates to a novel process for converting large cellular PVC boards for use as shingles. These large boards are readily available from many sources and therefore can be obtained at low cost. The subject process utilizes this material in a highly efficient way to produce cellular PVC shingles, with their many inherent advantages, at a cost comparable to conventional Western red cedar shingles that have been primed and field coated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic depicting an overview of an exemplary manufacturing process; 
         FIG. 2  is a schematic depicting an exemplary brushing assembly; 
         FIG. 3  is a schematic depicting an exemplary cross cut saw assembly; 
         FIG. 4  is a schematic depicting an exemplary parting saw assembly; 
         FIG. 5  is a schematic depicting an exemplary sizing saw assembly; 
         FIG. 6  is a schematic depicting an overview of another exemplary manufacturing process; and 
         FIG. 7  is a schematic depicting an overview of an exemplary shingle coating line 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Disclosed herein is a novel, in-line, method for preparing shingles formed from cellular PVC. Utilizing cellular PVC as the basic material for manufacturing the final shingle product produces a finished product free of checks, knots and other defects normally associated with wood shingles. Further, the manufacturing process of the present invention produces shingles that are extremely consistent in taper and squareness while minimizing waste by utilizing at least 98 percent of the raw material during manufacture. 
     Referring to  FIG. 1 , an exemplary method comprises brushing a top face and a bottom face of a cellular PVC board to create a textured pattern on the board via a brushing assembly  100 , cutting the board into specified shingle lengths via a cross cut saw assembly  200 , parting the cellular PVC board to create profiled boards via a parting saw assembly  300 , cutting the profiled cellular PVC boards into conventionally sized shingles via a sizing saw assembly  400 , and painting the resulting shingles. 
     More specifically, and referring to  FIGS. 2-5 , a cellular PVC board  10  is passed through a brushing assembly  100 , wherein the brushes forming brushing assembly  100  create a textured grain pattern along a length of board  10 . Brushing assembly  100  comprises a brush  102  adjacent to a brush  102 ′, and a brush  104  adjacent to a brush  104 ′, wherein brushes  102  and  102 ′ are oppositely situated to brushes  104  and  104 ′. Board  10 , which in an exemplary embodiment comprises an approximately ½ inch depth, an approximately 12 inch width, and an approximately 16 foot length, is passed lengthwise through brushing assembly  100  at approximately 30 feet per minute such that brushes  102  and  102 ′ brush against a top face  12  of board  10 , and brushes  104  and  104 ′ brush against a bottom face  14  of board  10  at a rate of about 1,000 revolutions per minute (“RPM”). To neutralize the forces exerted against board  10 , in an exemplary embodiment, brush  102  rotates in a direction opposite to that of brush  102 ′ and brush  104  rotates in a direction opposite to that of brush  104 ′ whilst board  10  is passing through brushing assembly  100 . For example, should brushes  102  and  104  rotate clockwise, brushes  102 ′ and  104 ′ preferably rotate counterclockwise. 
     In an exemplary embodiment, one or more of brushes  102 ,  102 ′,  104  and  104 ′ comprises densely packed bristles surrounding a steel tube core with an overall diameter of about 10 inches. Bristle characteristics such as density, temper, stiffness and varying length all combine to produce a brush, that when spun at approximately 1,000 RPM and brought against the surface of a cellular PVC board produces a surface texture that is generally identical in appearance to real rough-sawn wood. In an exemplary embodiment, the crimped, preferably copper plated, bristles comprise a gauge of about 28, and, preferably, randomly vary in length between about 1.75 inches to about 2 inches long. Furthermore, in an exemplary embodiment, the bristles are densely packed and pressed into a steel u-channel which is tightly spiral wrapped around an approximately 6 inch diameter tube. 
     After the brushing of cellular PVC board  10  is completed, cellular PVC board  10  passes in the direction of its grain through a cross cut saw assembly  200 . Referring to  FIG. 3 , an exemplary cross cut saw assembly comprises a cross cut saw  202  which cuts the cellular PVC board into a plurality of shingle length bolts  20 , wherein exemplary lengths include, for example, lengths of about 6 inches to about 25 inches, wherein about 7 inches to about 20 inches is more preferred, and wherein about 8.5 inches to about 18 inches is especially preferred. Cross cut assembly  200  further comprises a reference surface  203  which, when an edge of cellular PVC board  10  is positioned against reference surface  203 , positions cellular PVC board  10  for precise right angle cross cutting. Cross cut assembly further comprises a clamp  204  located in a cutting area which pneumatically clamps both sides of cellular PVC board  10  during cross cutting. 
     Once securely clamped via clamp  204 , cross cut saw  202 , which, in an exemplary embodiment comprises an approximately 18 inch diameter carbide tipped cross cut blade, cuts board  10 . Preferably the cross cut blade of cross cut saw  202  is positioned below cellular PVC board  10 &#39;s travelling surface, and rotates at approximately 1,200 RPM. When the timing is appropriate, the cross cut blade is preferably pneumatically and vertically raised to cross cut cellular PVC board  10 . The cross cut blade then drops back to the rest position and board  10  is unclamped. Board  10  may then be advanced to the next cut position and the next cut cycle may begin. 
     After passing through cross cut assembly  200 , bolts  20  pass, in the direction of their grain, into a parting saw assembly where, preferably, they are vertically stacked in a feeding magazine. Referring to  FIG. 4 , an exemplary parting saw assembly  300  comprises a high strain horizontal band saw  302  having two circular wheels  304  and  306  around which is strung a high strain, band saw blade  301 , which preferably comprises carbide saw tips, and which also preferably comprises a length of about 240 inches. 
     Parting saw assembly  300  further comprises a pallet handling system  310 . Pallet handling system  310  comprises a feeding magazine  311 , a cleated main feeding conveyor  312 , transfer mechanisms  313  and  315 , a return conveyor  314 , and a plurality of pallets  320 . Bolt  20  is pneumatically separated and released from the bottom of a stack of bolts fixtured in feeding magazine  311 , and dropped onto a pallet  320  positioned immediately beneath feeding magazine  311 . Bolt  20  is then fixtured to main feeding conveyor  312 . Pallets  320 , which preferably comprise polyurethane for cost, lubricity and wear resistance, are preferably designed to passively receive and precisely position dropped bolt  20  lying flat in a slightly canted or angled position such that when main feeding conveyor  312  conveys pallet  320  carrying fixtured bolt  20  through parting saw assembly  300 , bolt  20  will be parted or cut by band saw blade  301  across bolt  20 &#39;s thickness starting low on bolt  20 &#39;s leading edge and finishing high on bolt  20 &#39;s trailing edge thus producing a pair of profiled boards, and, more specifically, opposed, precisely tapered, full width shingles  30 . 
     Referring to  FIG. 5 , each newly parted shingle pair  30  sequentially emerges from parting saw assembly  300  and is pneumatically lifted from pallet  320  and placed on a cleated infeed conveyor  402 , where shingle pair  30  is transported, again in the direction of the shingles&#39; respective grains, into sizing saw assembly  400 . Sizing saw assembly  400  comprises an adjustable rip fence and saw blade  401 , wherein, in an exemplary embodiment, saw blade  401  comprises a diameter of about 18 inches, and/or incorporates carbide tipped cutting teeth. Rip fence and saw blade  401  cuts shingle pairs  30  into desired widths to create desired sized shingles  40 . In an exemplary embodiment, the throughput of sizing saw assembly  400  yields approximately one shingle per second. 
       FIG. 6  depicts another embodiment of an exemplary method of forming shingles from a cellular PVC board. The method depicted in  FIG. 6  differs from the method depicted in  FIG. 1  in that bolts are not formed at all. Rather, the cellular PVC boards are brushed cross-wise to achieve a wood grain finish perpendicular to the long direction of the cellular PVC board as opposed to parallel with the long direction, parted in a parting assembly  300 ′, and then conveyed, preferably at approximately 60 feet per minute, to a cross cut saw assembly  200 ′ where the cellular PVC boards are then cut into shingles having a desired width. Although the cellular PVC board may comprise a wide variety of dimensions, in an exemplary embodiment, as the cellular PVC board is fed through brushing assembly  100 ′, each of the boards comprises a depth of about 0.5 inch, a length of about 16 feet, and a width of about 8.5 inches, about 13 inches, about 18 inches, and the like. 
     More particularly, in an exemplary embodiment, a cellular PVC board  10  is fed through a brushing assembly  100 ′. Brushing assembly  100 ′ comprises a brush  106  adjacent to a brush  106 ′, and a brush  108  adjacent to a brush  108 ′, wherein brushes  106  and  106 ′ are oppositely situated to brushes  108  and  108 ′. Brushes  106  and  106 ′ are positioned to create a grain across top face  12  of board  10 , and brushes  108  and  108 ′ are positioned to create a grain across bottom face  14  of board  10 . Rather than creating the grain along a length of board  10 , as was done by brushing assembly  100  in the embodiments depicted in  FIGS. 1 and 2 , brushes  106 ,  106 ′,  108 , and  108 ′ create the grain crosswise to the length of board  10 , i.e., along the width of board  10 . Each of the brushes  106 ,  106 ′,  108 , and  108 ′ are preferably flying brushes which move at the same rate as cellular PVC board  10  by means of a multi-axis, servo-motor powered, coordinated, positioning system that moves the brush across the board while at the same time mimicking the feed speed of cellular PVC board  10  as it travels through brushing assembly  100 ′. 
     In an exemplary embodiment, brushes  106  and  106 ′, as well as their respective drive motors, are mounted within a two axis positioning system superstructure. This superstructure can suspend brushes  106  and  106 ′ above board  10 . During operation, brushes  106  and  106 ′ may pneumatically descend and move horizontally across top face  12  of board  10  by servo-motor actuation. This horizontal movement is preferably angled with respect to board  10 &#39;s long axis. This angle, coupled with the correct traverse speed of brushes  106  and  106 ′ produces a perpendicular brush motion relative to board  10 &#39;s long axis. After brushes  106  and  106 ′ have brushed top face  12  of board  10 , brushes  106  and  106 ′ may be pneumatically vertically retracted and moved horizontally back to their start position where the above described cycle may be repeated. The brushing cycle may be repeated at a rate such that the brushed pattern will be slightly overlapped to produce a continuous brushed pattern across the entire length of board  10 . The above described two brush, two axis, positioning system superstructure may be duplicated for brushes  108  and  108 ′, but is positioned beneath board  10  so as to brush bottom face  14  of board  10 . 
     After cellular PVC board  10  is fed through brushing assembly  100 ′, cellular PVC board  10  may be fed through parting saw assembly  300 ′. In an exemplary embodiment, parting saw assembly  300 ′ comprises a high strain horizontal band saw  302 ′ having circular wheels  304 ′ and  306 ′ around which is strung a band saw blade  301 . In an exemplary embodiment band saw blade  301  comprises carbide saw tips and has a length of about 320 inches. 
     In an exemplary application of parting saw assembly  300 ′, cellular PVC board  10  is laid flat and fed at approximately 60 feet per minute through parting saw assembly  300 ′ by a continuous motion conveyor. As it is fed in this manner, cellular PVC board  10  is continuously cut or parted into a pair of opposite facing, precisely profiled, shingle boards  25 , wherein each board of pair of shingle boards  25  preferably comprises a length of about 16 feet. The profile or taper is achieved by band saw blade  301  being tilted slightly relative to the conveyor running surface. 
     Once profiled, pair of shingle boards  25  is transported into a cross cut saw assembly  200 ′ in which each of the cellular PVC shingle boards pairs  25  is cut into desired-sized shingles  40 , wherein exemplary widths include, for example, about 4 inches to about 12 inches. In an exemplary method, one edge of shingle board pair  25  is brought against a reference surface to position the pair for precise right angle cross cutting. Pair of shingle boards  25  is advanced into the cutting area and securely, pneumatically clamped on both sides of the intended cut path. A carbide tipped cross cut blade, which in an exemplary embodiment comprises a diameter of approximately 18″, may be positioned below pair of shingle board  25 &#39;s travelling surface, may be rotated at approximately 1,200 RPM, and may be pneumatically raised vertically to cross cut pair of shingle boards  25 . The blade may then drop back to the rest position and board pair  25  may be unclamped. Pair of shingle boards  25  may then advance to the next cut position and the next cut cycle may begin. In an exemplary application, the throughput of the above described process may yield approximately four shingles per second. 
     Referring to  FIG. 7 , after emerging from any of the cross cut saw assemblies described above, the newly formed shingles may be transported to a shingle coating line  500  which comprises a flat line type, rotating head, paint booth  501 . In an exemplary embodiment, shingles  50  may be placed, manually and/or automatically, flatwise with brushed surface facing up onto an approximately 5 foot wide continuous motion, self cleaning conveyor  502 . Conveyor  502  may transport shingles  50  at approximately 25 feet per minute into a spray booth  503  housing a continuously rotating, approximately 4 foot diameter, spray head  504 , wherein, in an exemplary embodiment, spray head  504  comprises six spray nozzles. Each of shingles  50  is preferably coated with a two part polyurethane Polane paint to a wet thickness of approximately 5 mils. 
     After coating, shingles  50  emerge from spray booth  503  and are conveyed into a vertical drying oven  510 . In an exemplary embodiment, drying oven  510  comprises approximately 120 conveying trays  511  lying flat and stacked in tray elevators  512  and  512 ′, wherein tray elevator  512  ascends, and tray elevator  512 ′ descends. Each of conveying trays  511  is preferably a lightweight, externally powered, transport conveyor approximately 5 feet in length and width. 
     In continuous fashion, a conveying tray  511  is positioned at the output end of paint booth conveyor  502  where a drive motor  515  advances and docks with conveying tray  511 &#39;s drive shaft. A conveying tray&#39;s worth of wet shingles is then fully conveyed onto conveying tray  511 , drive motor  515  retracts, tray elevator  512  ascends on the input side and tray elevator  512 ′ descends on the output side index one level. Simultaneously during loading of each conveying tray  511  at the input of drying oven  510 , the following operations occur: dried shingles  60  are unloaded at drying oven  510 &#39;s output, a loaded conveying tray  511 ′ is transferred from the top of tray elevator  512  to the top of tray elevator  512 ′, and an unloaded conveying tray  511 ″ is transferred from the bottom of tray elevator  512 ′ to the bottom of tray elevator  512 . 
     In an exemplary embodiment, this entire mechanism and its operations are enclosed in an insulated enclosure  520  which comprises baffles and duct work to control heat, inlet air and exhaust as to subject each of the shingles to about 10 minutes of flash-off time at ambient temperature, about 20 minutes of cure time at approximately 130 degrees Fahrenheit, and about 10 minutes of cool down at ambient temperature. The above described coating/drying process yields approximately one shingle per second or approximately 2 squares (1 square=100 square feet) per hour. 
     It is additionally noted that prior to painting, a plurality of shingles formed by any of the above-discussed exemplary methods may be adhered to a backer board by means of a glue or other adhesive to form a shingle panel. In this embodiment, each shingle is preferably applied to the backer board such that the shingles in one row are not identically aligned with any of the shingles disposed in an adjacent row. Rather, the shingles are preferably disposed onto the backer board such that the shingles in one row are staggered in relation to the shingles in an immediately adjacent row(s). Once applied to the backer board, the newly formed panel may be painted and cured as above-described. 
     Although the principles of the present invention have been illustrated and explained in the context of certain specific embodiments, it will be appreciated by those of skill in the art that various modifications beyond those illustrated can be made to the disclosed embodiment without departing from the principles of the present invention.