Abstract:
An improved molded door having provisions for glass insert comprising at least 50% of said door&#39;s exterior surface includes a quadrilateral frame formed of a top rail, a bottom rail, a right stile and a left stile joined together, two sheets of molded door skins, each skin having a large central opening with an inwardly directed flange extending normal to its planer surface and around its respective opening, which flanges interlock when assembled on frame and form secondary frame for receiving a glass insert, means operable to join the skins to the quadrilateral frame, means operable to join the integral flanges of the skins in an interlocked relationship around their respective openings thereby forming an interlocked secondary frame for receiving a glass insert, a secondary left stile located between the joined flanges and the left stile with this stile joined to the skins and a secondary right stile located between the joined flanges and the right stile with this stile joined to said skins whereby the door supports said insert without twisting and bending when in service.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     A common place substitution for the traditional wooden doors in residential and commercial buildings are synthetic doors. One type of synthetic doors is formed with resin sheets reinforced with fiber glass (in the art referred to as skins) attached to opposite sides of a rectangular frame with resulting cavity between the skins filled with a plastic foam. Doors so constructed can include wood graining on their outer surfaces of the skins, and also raised paneling formed (molded) in the skins, which gives these doors the appearance of natural wood fabricated products. 
     Molded skins for making such doors of the type described are disclosed in U.S. Pat. No. 3,950,894 issued to DiMaio and in U.S. Pat. No. 4,550,540 issued to Thorn. These skins are typically formed using mixtures, having by weight 12% to 15% polyester resin, 5% to 15% polystyrene, 40% to 50% calcium carbonate and 15% to 25% chopped fiberglass. Such mixtures are layered in a compression molding machine and subjected to pressures from 600 to 1,500 psi for a cure cycle from 60 to 200 seconds to form rigid skins. The mixture described is one of those known ‘sheet molding compounds’ [SMCs]. A general description of the sheet molding process is found in an article entitled, “Compression Molding” by N. D. Simons in  Modern Plastics Encyclopedia , Vol. 54 No. 10A (1977-78). 
     Skins formed from SMC processes for doors can have thicknesses of from about 0.13 mm (0.05 inches) to about 52 mm (0.20 inches), depending on the door application in which they are used. 
     As previously noted such skins are affixed to opposite sides of a rectangular frame and the core (cavity) enclosed by the frame and skins is filled with a plastic foam to complete the door. A rigid urethane foam having a density of 0.8 pounds per cubic foot to 3.5 pounds per cubic foot is suitable for the core of such doors. 
     Prior art conventional molded doors of the type described can be generally classified, according to height, into two types: one is the standard molded door with a height of about 200 cm (or about 6 feet 8 inches), and the custom molded door with a height of about 250 cm (or about 8 feet), both doors are made in conventional widths, with the width of 94 cm (or about 3 feet) being the most common. Special molded doors may be 10 or 12 feet high. 
     In the past these prior art doors had glass inserts [lights] that covered less than 30% of the door&#39;s exterior surface, see e.g., U.S. Pat. No. 4,720,951 issued to Thorn. Currently the market place demands doors with large glass inserts or lights which can comprise more than 60% of the doors exterior surface. Due to building codes these large lights must be double glazed (double pane) and in some cases made of safety glass. As a result the insert may weigh in the range of 16.5 to 37.5 kilograms (44 to 100 lbs) and the skins in such doors are not capable of satisfactorily supporting this weight without innovations in the door structure for supporting the insert. This is particularly true in the taller, custom molded door structures and is especially true in the special molded doors described above. 
     This invention relates to improved molded doors composed of skins disposed on a door frame of stiles and rails which have a large central glass insert, by providing interior reinforcing means disposed adjacent to an insert frame structure formed in and joining the opposing skins, which cooperatively strengthen the door and enables a transfer of the weight of the insert to the door components without deformation or bending of the perimeter frame door due to the weight of the glass insert. Moreover the invention prevents flexing of the door components which otherwise might dislodge the large glass insert. 
     Thus it is an object to provide a molded door which is constructed in a manner to support large glass inserts while still taking advantage of the features available when using the SMC skins, such as wood graining, resistance to insect infestation, etc. 
     Another object of the invention is to arrange reinforcing (anti-bending means) in the interior of a custom molded door with large glass insert to strengthen it without creating an interference with the subsequent installation of the door hardware, e.g. latching mechanisms and hinges. 
     A further object of the invention is to incorporate internal structures in molded door with a large glass insert, particularly in the custom molded doors, to avoid deformation, flexing, twisting and the like resulting from the weight of the glass insert when the door is placed in service. 
     The further feature of the invention is to install reinforced anti-bending means inside a custom molded door with glass insert and against each internal wall of glass frame used for installing glass insert of molded door skin with opening to directly support the full weight of glass insert and strengthen the structural strength using anti-deformation and anti-bending elements. 
     SUMMARY OF THE INVENTION 
     An improved molded door having provisions for glass insert comprising at least 50% of said door&#39;s exterior surface includes a quadrilateral frame formed of a top rail, a bottom rail, a right stile and a left stile joined together, two sheets of molded door skins, each skin having a large central opening with an inwardly directed flange extending normal to its planer surface and around its respective opening, which flanges interlock when assembled on frame and form secondary frame for receiving a glass insert, means operable to join the skins to the quadrilateral frame, means operable to join the integral flanges of the skins in an interlocked relationship around their respective openings thereby forming an interlocked secondary frame for receiving a glass insert, a secondary left stile located between the joined flanges and the left stile with this stile joined to the skins and a secondary right stile located between the joined flanges and the right stile with this stile joined to said skins. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     This invention will be better understood by reference to this specification in conjunctions with the accompanying drawings wherein: 
     FIG. 1 is an exploded view of a conventional molded door with a large glass insert or light; 
     FIG. 2 is an exploded view of one embodiment of the invention; 
     FIG. 3 is plan of the improved molded door with one of the skins (top skin in the drawing) removed to show the internal structure of the embodiment shown in FIG. 2; 
     FIG. 4 is an exploded view of an alternative embodiment of the invention to that shown in FIG. 2; 
     FIG. 5 is plan of the improved molded door with one of the skins (top skin in the drawing) removed to show the internal structure of the embodiment shown in FIG. 4; 
     FIG. 6 is an exploded view of another embodiment of the invention showing two broad-faced reinforcing elements used to form the secondary left stile and secondary right stile and a metal extrusion forming the left stile and a metal extrusion forming the right stile; 
     FIG. 7 is a plan of the improved molded door with one of the skins (top skin in the drawing) removed to show the internal structure of the embodiment shown in FIG. 6; 
     FIG. 8 is a cross-section taken along the line  7 — 7  of the embodiment shown in FIG. 7 illustrating how the skins are joined with one another to form the interlocked frame for receiving the glass insert; 
     FIG. 9 is a plan of the improved molded door with one of the skins (top skin in the drawing) removed to show the internal structure of this embodiment of the invention with the secondary stiles abutted against the internal faces of the flanges forming the frame for the glass insert; 
     FIG. 10 is an exploded view of the embodiment of the invention shown in FIG. 9 better illustrating the channel or U-shaped reinforcing elements employed as the secondary stiles and using I-shaped connecting fittings for joining top and bottom ends of these secondary stiles. 
     FIG. 11 is a perspective of I-shaped connecting fittings shown in FIG. 10; 
     FIG. 12 is a cross-section of I-shaped fixing fittings shown in FIG. 11; 
     FIG. 13 is a perspective illustrating how the I-shaped fittings are used to join the channel or U-shaped reinforcing elements forming the secondary stiles shown in FIG. 9; 
     FIG. 14 is a perspective illustrating how I-shaped fittings shown in FIG. 13 can be used to join tubular reinforcing elements used as secondary stiles; 
     FIG. 15 is a cross-sectional of the embodiment shown in FIG. 9 illustrating the location of the channel or U-shaped reinforcing element abutting against the inside face of the interlocked frame for the glass insert; and 
     FIG. 16 is a cross-section of an the embodiment employing hollow reinforcing elements used as secondary stiles and abutting the inside face of the interlocked frame for the glass insert. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Applicant of the present invention engaged in serious research and development to obtain a suitable design for custom molded doors with large glass inserts. It was determined that the location of the reinforcement (anti-bending means) installed in the interior of the door for strengthening must not interfere with installation of the door hardware when door is placed in service. Accordingly, applicant developed several embodiments of the invention employing different reinforced structures with this fact in mind. All embodiments of the invention disclosed will prevent deformation and bending of the improved doors from the weight of the large glass insert to some degree, but the design where the reinforcing is placed against the integral secondary frame for the glass insert (see e.g., FIGS. 15 and 16 for details) is the most preferred embodiment as it provides improved stabilization of the door structure and better distribution of the weight of the insert to the skins and supporting frame. 
     Referring to FIG. 1, the exploded structure of a prior art door with glass insert is shown. It has two molded door skins  1 ,  2  each having a large aperture with an extending flange  11 ,  21  for receiving a glass insert  8 . The skins are attached to a top rail  3 , a bottom rail  4 , a right stile  5 , a left stile  6  after these components are joined to form a rectangular frame. To provide increased strength to the frame a reinforcing element  51  is joined to right stile, a second reinforcing element  61  is joined the left stile. A glazing rim  9  is employed to hold the glass insert in the aperture. 
     As indicated above the molded door skins  1  and  2  are formed sheet molding compounds and will have a thickness of about 1 to 4 mm. These molded doors are joined, typically with adhesives, to a quadrilateral frame. 
     The surface of said molded door skin with opening can be a smooth surface without graining or with graining wherein the depth the graining of about 0.05˜0.2 mm. Typically the underside or the opposite side of said molded door skins is formed with a rough surface to increase the surface area for the adhesive; this results in stronger bonds between the skins, foam and the frame. The assembled structure mentioned above is the basic structure used for both standard and custom molded doors with glass inserts. 
     Referring to FIG.  2  and FIG. 3, a preferred embodiment of the invention two broad-faced reinforcing elements  20 , formed of wood or foamed plastics or other materials and generally having a rectangular cross-section, are placed inside a custom molded door with a glass insert where flexing, deformation, and twisting are prevalent. These elements ate placed between the stiles  5 ,  6  and the interlocking secondary frame  300  for the glass insert (see FIG. 8 for this secondary frame detail) formed by special flanges  28  and  29  on skins  1  and  2  and are connected to these skins, with adhesives or the like. 
     The broad-faced reinforcing elements  20  may be positioned and be wide enough to provide anchoring structures for door hardware, such as latches, hinges and the like. For example if these elements are at least 10 mm (about 4 inches) in width, in combination with the interlocking secondary frame  300  for the insert, will provide stabilizing in most door structures of this type, including custom doors (those with a height of 250 mm (about 8 feet)). 
     After assembling the door structure shown in FIG. 2, the interior voids (cavities) are filled with polyurethane foam or PS, or the like. Thereafter the glass insert  8  can be inserted into the secondary frame  300  and then locked into the frame with a rim or keeper  301 , which relationship between the frame and insert is best illustrated in FIG.  8 . 
     An further enhanced version of the novel door shown in FIG.  2  and FIG. 3 is illustrated in FIGS. 4 and 5. In this embodiment a long reinforcing metal plate  30  is joined to each of the inside faces of said two broad-faced reinforcing elements  20  with screws, such as plastic screws, to increase the stiffness of these elements. Also as can be seen in FIG.  4  and FIG. 5, for sake of reducing costs and without affecting the structural strength, shorter broad-faced reinforcing elements  21  are employed, with a length shorter than said broad-faced reinforcing elements shown in FIG. 2 or FIG. 3, can be used with spacer  22  located at the bottom end of these elements to properly position them in the interior of the door when it is assembled. 
     Referring to FIG.  6  and FIG. 7, an embodiment of the invention two broad-faced reinforcing elements  23  forming the secondary stiles are married with a metal  241  left stile and metal right stile  241  of a custom molded door with glass insert. Referring to FIG. 8, the metal left stile illustrated as u-shaped member which has has inwardly directed ears  241 ( a ) that are used to join it to its broad-faced elements. As can be seen in this figure, grooves  231  are is formed at the outboard face of each broad-faced reinforcing elements  23  by cutting a predetermined depth from both side faces near the end of these elements. The outboard face of these elements are also milled so that the channel  241   b  in the metal stiles will slide onto these secondary stiles in an interlocking relationship. As the metal stiles are longer than their respective secondary stiles, the ends of rails at the top and bottom of the door can be milled to be received in the channel in stiles to lock the metal stiles with these rails. For more reinforcing a long metal plate  30  is connected to each secondary stile as shown in FIG.  8 . and as indicated it is screwed to the inboard face of each stile. 
     Referring to FIG. 9, the preferred embodiment of the invention is to install the secondary stiles (reinforcing and anti-bending means)  100  against each internal face of vertical wall of the secondary frame  300  formed with the molded door skins  1  and  2  (see secondary frame detail in FIGS. 8 and 15. Here the secondary stiles abut against the secondary frame and preferably ate attached to it by adhesives. As can be appreciated the weight of the glass insert in the secondary frame is concentrated at the bottom of this secondary frame the full weight of said glass insert  8  is located here and must be distributed to a significant area of skins of the door to prevent the skins from bulking from this weight by abutting the secondary stiles against the vertical inside faces of the secondary frame and gluing these stiles to the skins the weight is widely distributed and supported where it is concentrated. 
     In FIG. 10, a preferred constructions of the secondary stiles for the embodiment of FIG. 9 is illustrated. U-shaped metal reinforcing elements  101  are used to form the secondary stiles. This same material is used to form a top secondary rail  104  and the bottom secondary rail  105 . Four I-shaped fittings  17  are used to connect the ends of these metal stiles and rails, the details of which can be seen in FIGS. 11,  12  and  13 . In this preferred embodiment the metal secondary stiles and rails form an integral frame about the secondary frame  300  formed by the flanges  28  and  29  of the skins  1  and  2  with fittings  17  joining them. During assembly these secondary metal stiles and rails are bonded to the secondary frame and to the skins thereby creating a structure for distributing the weight of the glass insert  8  to the components of the door. While metal is preferred the U-shaped reinforcing materials  101 ,  104  and  105  can be metal, extrusion material, wood, or PVC extruded material. 
     When using metal for the secondary stiles and rails their ends must be mechanically connected. Fittings  17  shown in FIGS. 11 and 12, serve this purpose and generally have an “I” shape with a middle rib plate  173  connected to the middle of the top plate  171  and the middle of the bottom plate  172 . The top and bottom plates are parallel and the middle connection results in two U-shaped openings. In addition, a groove  175  which passes through the top plate  171  and the bottom plate  172  separates a portion of one of the U-shaped openings as can be seen in the figures mentioned above. At one side of the u-shaped openings the top and bottom plates are milled away to form recessed areas  174 . Using the metal secondary stiles the elasticity modulus is greatly improved over the use of wood elements as secondary stiles. A wooden secondary stile 100.4 mm in width and 40.4 mm in thickness has an elasticity value “E” of 1500 kg/mm 2 . In comparison an iron U shaped channel of a thickness of 2 mm and 40 mm in width with flanges of 22 mm has an “E” of 21000 kg/mm 2 . The improved elasticity modules in these doors achieved by using applicant&#39;s metal reinforcing versed wood can be calculated as follows: Improvement=21000/1500=14 since the “I” value is nearly the same for these materials. 
     Fitting  17  so constructed can be use to join the secondary metal stiles and rails shown in FIG. 9 as illustrated in FIG.  13 . It can be seen that the end of secondary stile  101  is received in the groove  175  and the recessed surfaces  174  of the fitting slide into the channel of the U-shaped stile. 
     In FIGS. 14 and 16 two hollow rectangular reinforcing elements or secondary stiles  102  are used to replace said two U-shaped reinforcing elements of secondary stiles  101  which are shown in FIGS. 8 and 15. When this substitution is made for the secondary stiles and secondary rails, the same fitting  17  can be used to join their ends to result in an integral frame encasing the secondary frame  300 . The material of said hollow rectangular reinforcing elements shown in these figures can be metal, wood, or PVC extruded material. 
     Assembling this kind of custom molded door with glass insert of the invention the right stile  5  and the left stile  6  are joined with the top rail  3  the bottom rail  4  to form the quadrilateral frame. The previously molded skin  1  is laid flat and this frame placed on the skin is glued to it, see lay out in FIG.  10 . Once this frame is in place the secondary stiles  102  can be placed against the inside surface of flange  28  of skin  1  and then the secondary top rail  104  is joined to the tops of the secondary stiles with fittings  17 . Next the bottom secondary rail  105  is placed against the bottom of flange  28  and also joined with fittings  17  to the secondary stiles. These secondary rails and stiles are joined to the interior surface of the flanges and the skin with glue or adhesive when installed and from an integral box around the flange. Next the surfaces of the rails and stiles of the frame and the secondary rails and stiles are coated with adhesive, and adhesive is also added to the mating surfaces of flange  28  after which the other skin  2  is added to the assembly. As can be seen in FIGS. 8 and 14 the flange  29  on this skin mates with flange  28  of skin  1  to form a secondary frame  300  for the glass insert. Since all the surfaces are coated with glue this skin closes the interior of the door and adheres to the pre-assembled parts. Joinder of the flanges form the secondary frame  300  for the glass insert. 
     Once this assembly is complete the voids or cavities between the skins and the stiles, rails, secondary stiles and rails, etc are filled with a plastic foam. Thereafter the glass insert  8  can be added and locked in place with the keeper  301  to complete the door.