You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to wall construction and, in particular, to a system utilizing factory built panels and associated hardware for constructing curved walls.  
         PRIOR ART  
         [0002]    Architects and/or building owners may specify curved interior walls to give rooms, partitions, corridors and the like a unique look, to create a focal point in the interior of the building, or otherwise depart from ordinary planar walls. Where the walls are to be finished with a hard finish other than plaster or drywall, it has often been the practice to construct a curved wall with custom millwork. This custom work, under most circumstances, is costly, because of the skilled labor and custom made panels or planks which, typically, are employed to create the curved surfaces. Consequently, architects and builders are restrained, due to the costs, from freely using their creativity in designing non-planar walls. Moreover, because each custom installation is just that, the final fit and finish of a custom built curved wall may be less than what is originally specified by the architect, thereby leading to further difficulties and controversies.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention provides a system of pre-manufactured panels and integrated hardware that produces concave or convex walls with a consistent high-quality appearance. The system utilizes specially fabricated rectangular panels of a height and width suitable for the customer&#39;s application. The panels are uniquely cut with dado slots on their rear faces to obtain horizontal flexibility and vertical stiffness. The panels have two opposed edges, normally the horizontal edges, kerfed to accept a spline and wall attachment clip while the other edges, typically the vertical edges, are square cut. The outer decorative face of a panel can take a variety of forms such as wood veneer, high-pressure laminate, metal veneer, or other known finishes.  
           [0004]    In accordance with the invention, the panels are interlocked to one another and retained against a subwall by special clips situated at the perimeter of each panel. Preferably, the spline used to join horizontal edges of adjacent panels is a flexible material such as extruded PVC so that it is readily manually bent on site into the radius of the wall. The vertical edges of adjacent panels are interconnected by joining them to vertical main rails with the use of panel clips secured to the rear faces of the panels. The main rails are attached to the sub-wall or framework and the panels, in turn, are fixed to the main rails by the panel clips. Advantageously, the slotted design of the panels as well as the character of the main rails, panel clips, retainer clips, and splines, enable the panel system to be used with any desired radius of curvature, both convex or concave above a certain minimum specified radius. Thus, the wall can have a changing radius and/or a serpentine configuration, as desired. As used herein, the term “cylindrical” is meant to describe a plane curved about one or more parallel axes.  
           [0005]    The disclosed panel system affords the look of custom millwork with high quality fit and finish, but at substantially lower cost than custom millwork. Additionally, the system enables a wall to be installed with less time and less skill than required by custom millwork. The unique hardware assures consistent alignment between adjacent panels without exposed fasteners or clips to achieve a handsome, quality appearance. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is an exploded fragmentary perspective view of the curved wall panel assembly of the invention;  
         [0007]    [0007]FIG. 2 is a fragmentary elevational view of the curved wall panel assembly of the invention;  
         [0008]    [0008]FIG. 3 is a cross-sectional fragmentary view of the curved wall panel assembly taken in the plane  3 - 3  shown both in FIG. 1 and FIG. 2;  
         [0009]    [0009]FIG. 4 is a fragmentary cross-sectional view of the curved wall assembly taken in the plane  4 - 4  shown in FIGS. 1 and 2; and  
         [0010]    [0010]FIG. 5 is a schematic representation of a curved wall constructed in accordance with the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0011]    Referring now to the drawings, a curved wall panel system  10  in accordance with the invention includes a plurality of rectangular panels  11 . In the following description, the panels and related hardware are indicated to have certain orientations which will produce a wall that is curved in a vertical column. The same parts can be turned 90° to produce a wall, arch, or ceiling that is curved in a horizontal column or turned in some other angle to produce a wall that is curved in an inclined column. Opposite vertical edges  12  of the panels  11  are joined or coupled to adjacent panel edges with main rails  13  and panel clips  14 . Opposite horizontal panel edges  16  have kerfs or slots  17  to receive a spline  18  and retainer clips  19 .  
         [0012]    The panels  11  are ordinarily rectangular in shape, it being understood that this description includes the condition of being square. The panels  11 , for the most part, will have the same shape and size but this need not be the case. Typically, the size of the panels both vertically and horizontally can be selected to compliment the application. The long dimension of a panel  11  typically would run in the horizontal direction but, if desired, can be arranged to run in the vertical direction; that is to say, the long dimension of a panel can run in a direction parallel to the axis of the cylindrical plane of the wall, or can run circumferentially along the cylindrical surface of the wall. Preferably, the panel  11  is fabricated of ¾″ thick wood composite material forming a core  15 . An outer decorative panel face  21  can be laminated to this composite core  15  at the factory to satisfy a customer&#39;s specifications. The decorative panel face may comprise, for example, wood veneer, high pressure laminate, sheet metal or other known finish materials. The edges  12 ,  16  can be stained, painted, laminated or the like with a color or finish to coordinate with the decorative outer face  21 . As shown, the vertical edges  12  are square cut. A rear face  22  of a panel  11  is machined with dado cuts in a direction parallel to the axis of the cylindrical section in which a panel is to be formed by bending or flexing action. The dado cuts or slots  22  are generally evenly spaced across the panel  11  and run the full distance between the kerfed edges  16 . As shown, the dado cuts  22  are in the shape of a dovetail such that the greatest width of a slot exists adjacent the finish face  21 . This configuration of the slots  22  achieves a high degree of flexibility in the horizontal direction while retaining stiffness in the perpendicular or vertical direction since the section modulus of the panel material between the slots is greater than that which would exist if the slots were rectangular in shape and had a width the same as the maximum width of the dado slot  22 . The dado cuts  22  are spaced a sufficient distance from the edges  12  to permit convenient, reliable attachment of the panel clips  14 .  
         [0013]    The panel clips  14  are preferably roll-form galvanized  24  gauge steel strips that are somewhat shorter, e.g. 4″ shorter than the vertical height of a panel  11  and are attached to the panel such that they are centered in the vertical dimension. As indicated in FIG. 3, the cross-section of the panel clips takes a form similar to a narrow Z-shape. More particularly, the clip includes a base flange  30 , a short web  31 , a main flange  32 , and a minor flange  33 . The base flange  30  is provided with spaced holes to receive fastening screws  34  screwed into the panel core  15  to attach the base flange firmly on the panel  11 . In its free configuration, a panel clip  14  with its base flange  30  abutted to a rear face  24  of the panel core  15 , can have a bend line or corner  36  between the main and minor flanges  32 ,  33  touching or nearly touching the core so that, as described later, it can firmly grip a part of a main rail  13 . As shown in FIG. 3, the web  31  holds the main flange  32  away from the core  15  to permit a part of a main rail  13  to be received between it and the adjacent area of the core or panel  11 . The panel clips  14  are assembled on the rear faces  24  of the core  15  in parallel alignment with the adjacent edges  12 .  
         [0014]    A main rail  13  is disposed between vertical edges  12  of adjacent panels  11 . The main rails  13  are rigid elements preferably made of extruded aluminum. A cross-section of a main rail  13  is illustrated in FIG. 3. The main rail  13  includes a generally centralized rib  40  adapted to separate the vertical edges  12  of adjacent panels  11  and a pair of oppositely extending flanges  41 ,  42 . A channel  43 , formed by a portion of the rib  40 , a web  44  and a flange  45 , exists between the rib and flange  42 . The channel or formation  43  receives hex head screws or like fasteners  46  and thereby ensures that there is no interference between such fasteners and the adjacent panel  11 . The channel  43  and, particularly the flange  45  and corresponding portion of the rib  40  allow the flanges  42 ,  41 , respectively, to stand off a sub-wall structure or sub-framework indicated by the numeral  47  to which the main rail  13  is attached by the screws  46 . This standoff or spaced relation between the flanges  41 ,  42  and subwall structure  47  allows the panel clips  14  to be received in the space between these flanges  41 ,  42  and the sub-wall  47 . With reference to FIG. 3, it will be seen that the central rib  40 , having oppositely extending beads  48  or equivalent structure, is adapted to properly space and vertically align the panels  11 .  
         [0015]    With reference to FIG. 4, a retainer clip  19  is shown in cross-section or profile. The retainer clip is conveniently made of extruded aluminum or other suitable material and is relatively short being, for example, about 2″ long. The profile of the retainer clip  19  is similar to a lower case “h”. A vertical part of the retainer clip section includes a web  50  having upper and lower horizontally extending flanges  51 ,  52 . Near the mid-section of the web  50 , the clip  19  includes a wall  53  extending horizontally from the web  50 . Integral with a free edge of the wall  53 , is a depending flange  54 . An integral rectangular bar  55  exists at the intersection of a lower face of the wall  53  and the web  50 . Vertical edges  56 ,  57 , of the flanges  51 ,  52  and a vertical face  58  of the bar  55 , lie in a common vertical plane and are adapted to operate to standoff or hold the panels  11  a predetermined distance away from the sub-wall or sub-framework  47 , this distance being the same as the predetermined standoff distance developed by the flanges  41 ,  42  of the main rails  13 . The depending flange  54  is spaced from the plane of the edges  56 ,  57 , and surface  58  so that it fits in the kerf  17  on the upper horizontal edge  16  of a panel  11  and so that it captures a section  59  of the panel edge  16  formed when the kerf is cut into this edge, preferably with a snug or push fit. A channel-like area  61  formed between the flange  51  and wall  53  receives a hex head screw or like fastener to secure the retainer clip  19  and, therefore, the associated panels  11  to the sub-wall  47 . The retainer clips  19  are located at spaced intervals along the upper horizontal edges  16  of the panels at an appropriate spacing of, for example, 8″. The spline  18 , preferably, is extruded of flexible polyvinylchloride. Other bendable or pliable materials are contemplated, such as rubber or other elastomeric material, or malleable material such as soft extruded aluminum. The spline  18  is precut to a length that matches the horizontal dimension of the panels  11 . The spline  18  has the general shape of a “T”. An upper part  63  of the spline fits snugly in the kerf  17  of the lower horizontal edge  16  of the superjacent panel  11  while a lower part  64  of the spline has a reduced thickness to enable it to fit in a kerf  17  on the upper edge  16  of the subjacent panel  11  along with the retainer clip flange  54 . It will be understood that the width of the kerfs  17  on the upper and lower horizontal edges  16  is the same for the sake of simplicity in manufacture of the panels  11 . At the vertical mid-section of the spline cross-section, the spline  18  includes an integral bar-like formation  66  having upper and lower horizontal surfaces  67 ,  68 . The lower horizontal surface  68  is adapted to bear against the upper horizontal edge  16  of the subjacent panel while the upper surface  67  is adapted to support the superjacent panel  11  by engagement with the lower horizontal surface of such panel. A decorative formation  69  can be integrated with the bar formation  66  of the splice to provide a finish for a vertical gap  71  between the upper and lower horizontal edges  16  of adjacent panels  11 . It will be understood that the splice  18  vertically and horizontally (in and out of the plane of the wall) aligns the panel edges  16  with which it is engaged.  
         [0016]    From the foregoing description of the system  10 , its assembly is self-evident. ordinarily, panels  11  are stacked one over the other for the full height of a wall. Suitable base trim blocking, not shown, can be utilized to support the bottom row of panels or, the bottom row of panels can simply rest on the floor. A main rail is attached to the sub-wall  47 ; the main rail may be modified as needed, where a curved wall starts so that it can be concealed by suitable trim, if desired. With the first main rail  13  or its equivalent installed in a vertical orientation, the panel clip  14  of the first panel  11  is slid over the flange  42  of the main rail  13 . The upper edge of this panel is attached to the sub-wall  47  with retainer clips  19  by positioning their depending flanges  54  into the kerf  17  on the upper horizontal edge  16  of the panel. The retainer clips  19  can be positioned with regular spacing along this edge such as on 8″ centers. It will be understood that the retaining function of the clips  19  will cause the panel to assume a radius of curvature corresponding to that of the sub-wall  47 , either convex or concave by flexing or bending the panel. The spline  18  is likewise manually bent on site into the curvature of the panel and forced into the kerf  17  on the upper horizontal edge  16 , the thinner flange or lower part  64  being oriented downwardly. Thereafter, the next vertical panel  11  is installed by sliding its panel clip  14  over the flange  42  of the main rail and fitting its kerf  17  on its lower horizontal edge  16  over the upper part or flange  63  of the underlying spline  18 . Successive panels  11  are installed one over the other in the same manner as described above.  
         [0017]    Next, another main rail  13  is installed by fitting its flange  41  into the space between the panel clips  14  and rear faces  24  of the first column of installed panels  11 . The main rail  13  is installed so that the channel  43  remains temporarily exposed to receive the mounting screws  46 . After this rail is secured by the screws  46 , another column of panels  11  is assembled on the sub-wall  47  and this process is repeated column by column until a wall is completed. The last column of panels  11  can be fitted with suitable trim as desired; similarly, top and bottom horizontal trim can be used at the floor and ceiling.  
         [0018]    From the foregoing disclosure, it will be seen that a curved wall can be constructed with essentially any desired radius greater than a minimum of, for example, 7′. The wall installation requires relatively little labor and skill to afford a custom quality look. The connection between the panel clips  14  and main rails  13  is somewhat self-adjusting due to the ability of the panel clips  14  to flex slightly so as to allow the cantilevered bend line  36  to be displaced away from the rear face  24  of a panel and, thereby allow the vertical edge area of a panel to conform or be somewhat tangent to the curvature imposed on the panel  11  by the sub-wall  47 .  
         [0019]    It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.

Summary:
The invention comprises a system for constructing a finished convex or concave curved wall of any desired radius beyond a specified minimum. The wall is constructed of pre-finished rectangular panels retained on a sub-wall structure in horizontal rows and vertical columns. The panels are retained on the sub-wall structure with vertical rails at their vertical edges and retainer clips spaced along their horizontal edges. The panels are slotted at their rear face to provide rigidity in the vertical direction and flexibility in the horizontal direction. The horizontal edges of the panels are kerfed to receive the retainer clips and flexible splice strips that conform to the curvature of the wall and align and space a panel with the panel immediately above it. Clips attaching vertical edges of the panels to the rails allow the associated areas of the panels to align tangentially with the curvature of the wall.