Abstract:
A method and apparatus to produce decorative mouldings, wall panel sections and columns, which are widely used in the construction industry. The method is a sequence of advancing a core, constructed from preformed expanded polystyrene (EPS), in a straight horizontal plane, with restraining devices preventing lateral and vertical movements, through a coating chamber. The coating chamber is filled with a thick liquid stucco or plaster or cement-like mixture and imparts a layer of the coating on the preformed core. The thickness of the coating layer is controlled with templates having an opening correspondingly larger than the core size and with the desired decorative profile. The apparatus can be configured to apply the coating on all sides of the core. In the case of a decorative moulding, the coating application can be limited to the exposed decorative surfaces only.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to decorative mouldings, wall panels and hollow decorative columns of the type used in the construction industry comprised of preformed foam cores with a stucco/plaster coating. The invention relates particularly to a method and apparatus for coating the cores with stucco/plaster.  
       BACKGROUND OF THE INVENTION  
       [0002]     Preformed and prefabricated components are becoming widely used in the construction industry. Examples of such components include prefabricated wall sections, trusses, preformed foam trims and arches.  
         [0003]     Components also include decorative mouldings, wall panels and columns, preformed and finished and ready to be installed on the construction site. These components are typically comprised of an expanded polystyrene (EPS) core and coated with a plaster or stucco-like material to provide an attractive decorative finished surface. A fibre mesh can be applied to the core prior to coating to improve strength and durability.  
         [0004]     The prevalent method of producing the decorative components is to align rows of the cores on plastic topped tables and staple or screw them to the tabletop. There could be as many as four rows of cores placed side by side on a 4 ft. wide table, extending up to 90 ft. long or more. If required, the cores would have had mesh applied prior to placing them on the table.  
         [0005]     The coating material is poured from a pail along the length of the cores and massaged by hand on to the exposed surfaces of the cores. A box, with a steel template cut to a finish profile, is then slid along the length of the table, thus imparting the finished profile on the workpiece. The workpiece is allowed to dry, and another coating can be applied with a finer grained material to impart a smoother finish.  
         [0006]     In the case of a decorative column, the cores are constructed in elongated halves and are placed on the tables with the split facing down. After coating the halves, they are bonded together and repaired at the seams.  
         [0007]     After allowing the workpiece to completely dry, it is then pried off the table. The edges that were defined by the tabletop can be sanded and any minor imperfections can be repaired. The finished workpiece is then shipped.  
         [0008]     This whole process takes about 24 hours and requires after clean up of the tabletops, removal of the screws and cleaning of the box and template. This method is very costly in terms of labour and space.  
         [0009]     More recently, various types of automated equipment have been produced to apply the coating. For example, Canadian patent application serial number 2229933 filed on Feb. 19, 1998 by Oscar et al discloses a method and apparatus for coating a decorative workpiece. This apparatus drives a core through a coating chamber with a pair of conveyor belts with spikes penetrating the core from the bottom surface. The core is driven through a pressurized coating chamber by the conveyor belts. An elongate channel or dovetail is pre-cut in the bottom of the core that engages on a corresponding rail on the apparatus, and holds the core against lateral and vertical movement as it is coated. While this method and apparatus does provide a coating on the decorative surface of the .workpiece, it can be very troublesome in practice. If the cores are not tightly placed end to end with each other as they pass through the coating chamber, the coating material leaks on to the conveyor belts and rail. The leaked material can accumulate as lumps on the belts and impart an uneven finish on the workpiece. Furthermore, as the last core passes through the coating chamber, all the excess material falls onto the rail and spiked belts thus requiring a meticulous cleanup.  
         [0010]     Additionally, the apparatus disclosed in Canadian patent application 2229933 does not allow for coating the underside of a core and is extremely limited in its application in coating decorative inside corner mouldings. Also, an undesirable channel or dovetail is required on the underside of the core. Furthermore, because the ends of the coating chamber are angled, the templates are not easily produced because of the complicated rendering of the resulting perpendicular section required on the workpiece.  
         [0011]     Canadian patent 2,184,205 issued on Jan. 27, 1998 and reissued on Sep. 7, 1999 to 888804 Ontario Limited, discloses a method and apparatus for manufacturing decorative mouldings. In this method, the workpiece is driven by conveyor belts abutting both sides of the workpiece before passing through a coating chamber while being slidingly engaged with a continuous flat tabletop. While this apparatus does provide a coating on the decorative surface of the workpiece, it is also troublesome and limited in its application. Firstly, if the cores are not tightly butted up against each other, end to end, the coating material leaks on to the tabletop, accumulates and affects the thickness of the coating. Holding the cores against the tabletop as they pass through the coating chamber creates friction that makes the cores harder to drive through the coating chamber. For inside corner mouldings, the conveyor belts cannot drive against two corners on the sides of the core. The belts rip the corners of the core before entering the coating chamber. Slipping can occur which results in an uneven surface finish. Pieces of the core are carried into the coating chamber and contaminate the mix. The dies as illustrated in the patent with tapered openings having sharp inside corners are not easily achieved, except by hand grinding and filing, making them too costly. Additionally, the apparatus does not allow for coating the underside of the core.  
         [0012]     Both of these apparatus and methods are intended to by set up and operated in a dedicated facility with an area set up for their use requiring costly floor space. Neither of the apparatus allow for the convenience of portability to the actual construction site.  
         [0013]     Therefore, there is a need to develop a method and apparatus for coating the cored workpieces that allow for coating on all sides, that can be portable and is equipped with a drive mechanism and coating chamber that is not prone to the difficulties encountered with the prior art.  
       SUMMARY OF THE INVENTION  
       [0014]     To this end, in one of its aspects, the invention provides a novel method and apparatus for applying a plaster/stucco-like coating material to the surfaces of an elongate foam core. The foam core is preformed with a profile resembling the desired finish surface profile and may or may not have a reinforcing mesh applied to its surface prior to coating.  
         [0015]     The foam core can be used for wall panels, decorative exterior/interior mouldings or columns.  
         [0016]     Accordingly, the present invention discloses a method for applying a plaster/stuccolike coating to the surfaces of an elongate foam core comprising the steps of: 
        Continuously advancing the core in a straight horizontal plane, with hold down wheels constraining the core downwardly as it is penetrated along the bottom surface by a series of driving dogs;     Constraining the said cores, vertically and laterally, while inside a coating chamber, as the core advances through an input and output template as a plaster/stucco-like material is applied to the surfaces of the core;     Supporting the said core, while inside a coating chamber, vertically with ledges that adjust to slide under the bottom sides by approximately ¼″ in the case of coating only the visible decorative surfaces of a core;     Advancing the core through an input template opening made of steel or plastic with an opening corresponding to the profile of the core and large enough to accommodate the said core with enough clearance to allow the core to pass through the input template even if the core had been previously coated;     Advancing the core through an output template laminated with a steel template conforming to the desired finish profile. The said core being preformed to a shape conforming to the desired profile but correspondingly smaller by an amount equal to the desired thickness of the coating. A plastic template bonded or screwed to the steel template, thicker than the steel template, bevelled with the smaller opening corresponding to the steel template profile with the larger side opening up like a funnel with radiused corners facing inside the coating chamber;     Filling the coating chamber with plastic/stucco-like material by first inserting the foam core so that the input and output template openings are filled with the core, and keeping the coating chamber filled as the cores advance through, one after the other;     Advancing the coated core on to a roller conveyor or slotted table top and removing the core from the apparatus and placing the coated cores on racks or tables to dry;     Inserting the coated and dried cores back into the apparatus for a subsequent coating with a thinner or finer grained coating material to provide smoother surface;     Changing the output template to a larger profiled opening when applying a subsequent coating.        
 
         [0026]     According to another object of the present invention is an apparatus for applying a plaster/stucco-like coating material to the surface of a profiled elongate foam core on all sides or on the desired exposed surfaces only, said apparatus comprising: 
        Means for advancing a core on a straight horizontal plane through the apparatus;     Means of constraining the core laterally and vertically as it advances through the apparatus;     Means to allow adjustment of the apparatus to take various size cores;     Means to allow configuration of a coating chamber to provide a continuous coating on all sides of a core;     Means to allow configuration of a coating chamber to provide a coating on the exposed surfaces only of a core;     Means to allow said apparatus to be portable with easily removable and packaged components;     Means of imparting a surface profile on the core surface by the use of a coating chamber with input and output templates;     Means of providing easy cleanout of the said coating chamber;        
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]      FIG. 1   a  is a perspective view of a apparatus of the present invention showing a core advancing through the apparatus.  FIG. 1   b  is an enlargement of the central section of this apparatus.  
         [0036]      FIGS. 2A and 2B  show a perspective view of two decorative mouldings, one wall panel and one column.  
         [0037]      FIG. 3A  is an end view showing the core as it enters the coating chamber.  FIG. 3B  is a side view of the chain and sprocket assembly.  
         [0038]      FIG. 4  is an end view showing the core as it inters the input template. Illustrated is the clearance required between the core and the template. Also shown is a configuration of the apparatus enabling a column to be coated on all surfaces.  
         [0039]      FIG. 5  is a section view of the coating chamber facing the output template.  
         [0040]      FIG. 6  shows the construction of the output template an a wire frame perspective of the plastic laminate.  
         [0041]      FIG. 7  is a longitudinal side view section of the coating chamber illustrating the core advancing through.  
         [0042]      FIG. 8   a  is a perspective view of one apparatus of the present invention showing a core advancing through the machine.  FIG. 8   b  is an enlargement of the central section of this apparatus.  
         [0043]      FIG. 9  is an end view showing the core as it enters the coating chamber. A side view of the chain and sprocket is shown below.  
         [0044]      FIG. 10  is a perspective of a side guide. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]     Referring to  FIG. 1 , there is illustrated apparatus  29  of the present invention This apparatus is intended to coat cores up to 18″ wide. The workpiece  18  as shown in  FIG. 2   a  comprises a core  10  having an exterior decorative surface  13  which may be irregular in cross-section, but elongated and consistent along its entire length. A bottom surface  14  is flat and remains uncoated. A mesh  11  covers the entire decorative surface  13  of the workpiece and may overlap the sides to fold under on to surface  14 .  
         [0046]     The workpiece  18  of  FIG. 2A  is designed to be mounted on an exterior wall by cementing it in place via bottom surface  14 . Workpiece  19  of  FIG. 2C  is an interior inside corner moulding and is attached by cementing surfaces  14   a  and  14   b  to a wall section. Workpiece  20  of  FIG. 2B  is a wall section. Workpiece  21  of  FIG. 2D  is a contoured column.  
         [0047]     Apparatus  29  as shown in  FIG. 1   a  is configured to take an exterior moulding core  10 .  
         [0048]     Referring to  FIG. 1   b , the foam core  10  is placed on loading table  30  and pushed by hand to go under hold down wheel  31  and between two side guides  32 . The hold down wheel  31  is connected to a fully articulating arm attached to a column that allows for adjusting to different heights and widths of cores  10 ,  15 ,  16 ,  17 . The side guides  32  slide on two rails  33  to allow for different core widths and allow the core to be centered in relationship to drive dogs  35 .  
         [0049]     Once the core is partially pushed into the side guides  32 , driving dogs  35  that are connected to a chain and sprocket  34  are used to advance the core  10  further along horizontally. The chain and sprocket  32  can be powered by either a hand wheel  37  manually or engaging a variable speed motor  36 .  
         [0050]     The leading edge of the core  10  passes through the side guides  32  and is pressed down by a second hold down wheel  43  and continues on through the input template  44 .  FIG. 3   a  discloses a sectional view of core  10  as it leaves the side guides  32 , looking towards the input template.  
         [0051]     Core  10  advances through the input template  44  and into the coating chamber. The input template  44  is cut with a profile slightly larger than the core  10 .  FIG. 4  illustrates the core  10 , 15 , 16 , 17  entering the input template  44 . The clearance “C” has to be enough so that if the core requires more than one pass through the apparatus, it can still fit through the template with some allowance for irregularities.  
         [0052]     Referring to  FIG. 5 , the core  10  continues to advance through the coating chamber. The coating chamber is defined as a box having laterally adjustable sidewalls  42 , an input template  44 , an output template  46  and a coating chamber bottom  48  (see  FIG. 7 ).  
         [0053]     Referring to  FIG. 5 , the core  10  advances into the guide wheel assembly  45 . The guide wheel assembly  45  adjusts vertically and laterally and is shaped to roll against the top corners of the core  10 , 15 , 16 . The guide wheel assembly is designed to align the core laterally to the exit template  46  and holds the core down against laterally adjustable support ledge plates.  
         [0054]     Referring to  FIG. 5 , the support ledge plates  39  are intended to provide a vertical supporting surface for cores  10 , 15 , 16  and are laterally adjustable so that the ledge extends under the bottom surface  14  by approximately ¼″, thus reducing friction that would be encountered with a continuous supporting surface. The support ledges  39 , in combination with core  10 , 15 , 16 , form a sliding seal  49  that prevents the coating material from escaping through the bottom.  
         [0055]     When the last core  10 , 15 , 16  passes through the coating chamber, the ledge seal  49  no longer exists and thus the excess coating material is free to fall through into a collection pail.  
         [0056]     In the case of core  17 , the guide wheel assembly  45  and support ledges  39  are not used. Referring to  FIG. 4 , the templates  44  and ( 46  not shown) are extended to protrude below the core  17  and a bottom  48  is attached.  
         [0057]     Referring to  FIG. 1 , the core advances through the output template  46 .  
         [0058]     Referring to  FIG. 6 , the output template  46  is made form from a steel plate that may be laminated to a thicker bevelled plastic template that funnels the coating material on to the surface of the core  10 , 15 , 16 , 1 . 7 . The plastic portion is generally profiled to conform to the steel profile but is radiused in the corners and the edges. The radii are tapered forming a coned profile that increases in radius the further back from the plate side at an angle equal to the plastic bevel angle.  
         [0059]     The output template  46  is sized to the desired dimension of the finish workpiece  18 , 19 , 20 , 21 . The core  10 , 15 , 16 , 17  was preformed smaller than the finished workpiece by an amount equal to the desired coating thickness.  
         [0060]     Referring to  FIG. 7 , the cross section horizontally through the coating chamber is illustrated. In the case of core  17 , the input template  44  and the output template  46  can be place closer together, based upon the size of core  17  and how much said core can be extended through the coating chamber unsupported.  
         [0061]     As the core advances past the output template  46 , scraper  50  removes any excess material that may have squeezed on to the bottom edge  14 .  
         [0062]     Referring to  FIG. 1 , the now coated workpiece  18 , 19 , 20  advances on to an output roller conveyor  47  and can be lifted off by hand and placed on drying racks.  
         [0063]     Uncoated cores are continuously fed end to end into the side guides  32 . No gap is permitted between the cores; otherwise the coating material would fall through the coating chamber.  
         [0064]     The entire apparatus  29  can be disassembled into four sections for ease of portability. The coating section  52  has four hinged legs  51  that can be folded for storage. Input section  53  fits into a channel in coating section  52  and can be locked in place. The input section had two hinged legs  51 . Output section  54  fits into a channel of coating section  52  and also has two hinged legs  51  and can be locked in place.  
         [0065]     Drive motor  36  and hand wheel  37  are designed to slip on and off for shipping,  
         [0066]     Another embodiment of the present invention is apparatus  100  shown in  FIGS. 8   a ,  8   b . This apparatus is more heavy duty in nature and is capable of coating cores up to 36″ wide and is not intended to be portable.  
         [0067]     Apparatus  100  as shown on  FIGS. 8   a ,  8   b  is illustrated to take core  10 .  
         [0068]     The core  10  is placed on a loading table  130  and pushed by hand under hold down wheel  131  and between the two rotating side guides  132 . The hold down wheel  131  is connected to a fully articulating arm attached to a column that allows for adjusting to different heights and widths of cores  10 , 15 , 16 . The rotating side guides  132  slide on two rails. A width adjusting mechanism  150  comprised of a hand wheel, rack and pinion and bevel gears adjusts the opening between the two rotating side guides  132  to allow for different core sizes. By turning the hand wheel on adjusting mechanism  150 , both rotating side guides move laterally simultaneously, thus adjusting for various widths and maintaining centrality on the table and in relationship to drive dogs  135 .  
         [0069]     Once the core  10  is partially pushed into the rotating side guide  132 , driving dogs  135 , penetrate into the bottom  14  of the core  10  and advances the core further along horizontally. As with apparatus  29   FIG. 1 , rotating a hand wheel  37  manually, or engaging a variable speed motor  36  can power the chain and sprocket  134 .  
         [0070]     Referring to  FIG. 9 , the leading edge of the core  10  advances through the side guides  132  and is pressed down by a second hold down wheel  143  and advances to the input template.  FIG. 9  is a section view taken through the side guides  132  looking towards the coating chamber.  
         [0071]     The rotating side guides  132  are connected to the chain and sprocket  134  by a set of bevel gears that rotate the side guides  132  synchronous to the chain and sprocket  134 . Referring to  FIG. 10 , the side guides are comprised of a belt  151  and two rollers  152  with a backing pad  153 .  
         [0072]     As the chain and sprocket  134  advances the drive dogs  135 , the side guide belts  151  rotate at the same speed and centrally locates and guides the core  10 . The core  10  is thus advanced by drive dogs  135  and held central by the guide belts  151  without the core encountering side sliding friction.  
         [0073]     Referring to  FIG. 4 , core  10  advances to the input template  44 . The input template is cut with a profile slightly larger than the core  10 , 15 , 16  with enough clearance that if the core requires more than one coating pass, it can still fit through with some allowance for irregularities.  
         [0074]     The core  10  continues to advance into the coating chamber and is guided by the guide wheel assembly  45  (see  FIG. 5 ). The configuration of the coating chamber is the same as the first apparatus except for bottom ledge  39  is replaced with support fork  139  (see  FIG. 9 ).  
         [0075]     The support fork  139  is an extension of the rotating side guides  132  and operates laterally for core size adjustment by actuating the width adjustment mechanism  150 . This provides the ability to make one adjustment to set the correct width and ledge support.  
         [0076]     The remainder of the second embodiment works the same as the first embodiment except that it is larger and without portability.  
         [0077]     While many specific structural details have been disclosed, it will be understood that it is capable of many modifications and that this application is intended to cover any variation, uses, adaptions of the invention, following in general the principles of the invention including such departures from the present disclosure as to come within the knowledge of customary practice in the art, and as may be applied to the essential features hereinbefore set forth and falling within the scope of the invention or the limits of the appended claims.