Abstract:
A door having a plurality of channel-shaped frame members encircling a core and being coupled to one another by interfitting dimples and projections at the confronting ends of adjacent frame members. On opposite sides of the core are panels having lips which are accommodated in grooves formed in the frame members. The components of the door may be assembled without the need for any tools and such components may be maintained in assembled condition without the use of separate fastening devices such as bolts, nails, screws, and the like, or any fixtures or measuring devices.

Description:
This invention relates to a door construction and more particularly to a door having at its perimeter vertical and horizontal frame members, panels on opposite sides, and a core between the panels and spanning the space between the frame members, all of such parts being assembled and retained in assembled relation without requiring the use of any bolts, screws, or other fasteners. 
     BACKGROUND OF THE INVENTION 
     Interior and exterior doors conventionally are formed by assembling a plurality of frame members and other components which are joined and maintained assembled by various kinds of fastening devices such as bolts, screws, nails, and the like. The necessity of having to use fastening devices separate from the door components themselves is objectionable for a number of reasons. For example, an inventory of and storage facilities for such fasteners must be maintained. Fasteners needed from time to time must be removed from storage and applied manually to a door under construction. The manual application of such fastening devices inevitably results in imperfections due to differences in skills, experience, and other factors affecting the assemblers. Doors which are not uniform in manufacture cannot be uniform in use. Consequently, some doors fit better than others, have a better appearance, and provide greater trouble-free operation. 
     A principal object of the invention is to provide a door construction which overcomes the disadvantages referred to above. 
     SUMMARY OF THE INVENTION 
     A door constructed in accordance with the invention comprises a plurality of separate frame members which, when assembled, form a quadrangular frame of such size as to be accommodated in a doorway. Each frame member is channel-shaped and has a pair of spaced, parallel flanges joined at corresponding edges by a web. At the juncture between the web and each flange is a groove which extends the full length of the frame member. The ends of each frame member are mitered or shaped to form a substantially right-angular joint and the flange of each frame member has an extension at each end which projects beyond such flange. 
     The extensions are so arranged that, at each of the confronting ends of a pair of frame members, the extensions of the flanges of one of the frame members overlap the extensions on the flanges of the adjacent frame member. The overlapping flanges have cooperating dimples and projections which nest with one another and maintain the frame members assembled. 
     A core formed of insulating material spans the frame members and is accommodated in the channels of the frame members. The core is sandwiched between two external panels which preferably are adhesively secured to the core and to the confronting surfaces of the frame members. The marginal edge of each panel has a lip which is accommodated in the groove of each frame member and adhesively secured thereto. 
     If the door is one which should have a lock and/or latch mechanism associated therewith, a portion of the core may be cut away to accommodate a lock/latch mechanism support block and either or both of the panels may be provided with an opening to provide access to the lock/latch mechanism. The frame member associated with the lock/latch mechanism may be provided with an opening for accommodation of the lock and/or latch. 
     The panels may be flush or embossed and solid or provided with openings to accommodate one or more lights, in which case the core will be provided with a corresponding opening or openings. 
    
    
     THE DRAWINGS 
     A door constructed in accordance with the preferred embodiment of the invention is illustrated in the accompanying drawings in which: 
     FIG. 1 is an isometric view of a finished door; 
     FIG. 2 is an exploded view, on an enlarged scale, of the door shown in FIG. 1; 
     FIG. 3 is an exploded view of two of the frame members illustrating the manner in which they may be assembled; 
     FIG. 4 is a fragmentary, elevational view showing two adjacent frame members assembled with one another and supporting a core; and 
     FIGS. 5 and 6 are enlarged sectional views taken on the lines  5 - 5  and  6 - 6 , respectively, of FIG.  4 . 
    
    
     DETAILED DESCRIPTION 
     A door constructed in accordance with the invention is designated generally by the reference character  1  and comprises four separate frame members  2 ,  3 ,  4 , and  5 , the members  2  and  4  being parallel to but spaced apart from one another and the members  3  and  5  being parallel to and spaced apart to each other. The frame members  2 - 5  are arranged and joined to one another in such manner as to form a closed, quadrangular frame, the members  2  and  4  constituting cross members and the members  3  and  5  constituting stiles. 
     Each of the frame members  2 - 5  is of channel configuration having a pair of parallel flanges  6  and  7  joined by a planar web  8 . At the juncture of the flanges  6  and  7  with the web  8  the flanges are reversely turned as at  9  (FIG. 5) to form grooves  10  and  11  which extend the full length of each frame member. 
     The free ends  12  and  13  of the flanges  6  and  7  are mitered or beveled so that when the ends of two adjacent frame members are placed together the two members extend substantially normal to one another. 
     Each of the flanges  6  and  7  of the frame members  2  and  4  has an extension  14  which projects beyond the mitered end of the associated flange, and each of the flanges  6  and  7  of the frame members  3  and  5  has a corresponding extension  14   a . The extensions  14  are offset from the plane of the flanges  6  and  7  in a direction toward one another by an amount sufficient to enable the extensions  14  to be accommodated between and overlap the extensions  14   a . See FIG.  5 . Otherwise, the space between the flanges;  6  and  7  of each of the frame members is the same. The free edge of each of the extensions  14  is turned inwardly or toward one another as is indicated at  16  in FIG. 5, to facilitate nesting of the extensions. 
     The extensions  14  and  14   a  are provided with cooperable coupling means  17  for maintaining the frame members in assembled relation. In the preferred embodiment the coupling means comprises a substantially hemispherical dimple or depression  18  in each of the extensions  14  and a substantially hemispherical projection  19  in each of the extensions  15  which confronts the dimple in the adjacent extension so as to be accommodated therein. 
     The frame members may be fitted together and maintained in assembled relation without the use of any tools, fixtures or measuring devices. When assembled the frame members will be secure and maintain the correct size and squareness of the door frame. 
     The door construction preferably includes a core  20  having a reduced thickness marginal edge  21  of such size as freely to be accommodated between the flanges of each of the channel-shaped frame members  2 - 5 . The core preferably is formed from an environmentally safe, CFC-free polystyrene which is self extinguishing and non-toxic when burned. The core  20  is thermally insulating and may be shaped prior to its assembly with the frame members  2 - 5  to fit within the channel-forming flanges  6  and  7 , as well as between the extensions  14 . 
     If the finished door is to have recessed panels, as indicated at  22  in FIGS. 1 and 2, the core  20  may be molded, compressed, or indented, as shown at  23  in FIG.  2 . Further, if the door is to be provided with a locking mechanism, one side of the core may be cut away to form a recess  24  (FIG. 2) in which a wood or other block  25  may be glued or otherwise suitably secured, and the block  25  may be provided with suitable openings (not shown) for the accommodation of a latch and/or bolt locking mechanism. The web  8  of the adjacent frame member  5  will have to be provided with one or more openings (not shown) to accommodate the latch and/or bolt mechanism. 
     The door construction is completed by the inclusion of a pair of exterior panels  26  which preferably are formed of metal sheets of such size as to span all of the frame members  2 - 5  when the latter are assembled. Each panel  26  may be planar, if the door is to be a flush door, or embossed to provide indentations  23  corresponding to the indentions  22  formed in the core  20 . If the door is to be provided with a latch/lock mechanism  28  and a knob  29 , the panels  26  may be provided with openings for the accommodation of such parts. 
     Each of the panels  26  has at three of its four sides a right-angular lip  30  of such thickness as to be accommodated in the groove  10  or  11  of each frame member with the core sandwiched between the panels. The inner surface of each lip bears snugly against and grips the confronting surface of the frame member. No lip is provided at that end of the panel which will be at the bottom of the door for a reason to be explained. 
     To assemble the components of the door the frame members  2 - 5  are applied to the edges of the core  20  by inserting the four edges of the core between the flanges  6  and  7  of each of the frame members. The inner surface of each of the turns  9  should seat on the associated edge  21  of the core  20 . As two adjacent frame members are fitted to the core, the extensions  14  may be inserted between the extensions  14   a  so that the projections  19  are accommodated in the dimples  18 . 
     Once the frame members have been applied to the core and coupled to one another via the coupling means  17 , an adhesive coating is applied to the opposite sides of the core and to the exterior surfaces of the channel flanges  6  and  7 . The panels  26  then may be applied to opposite sides of the core and the lips  30  of the panels fitted into the grooves  10  and  11  along the top and sides of the frame members. The lips  30  also may be coated with suitable adhesive so as to secure the lips within the grooves of the frame members. 
     The adhesive used may be any one of a number of readily available adhesives. One suitable adhesive is a polyurethane adhesive manufactured by Stabond Company of Glendena, California. Other known, appropriate adhesives may be used, if desired. 
     By omitting the lip  30  from the edges of the panels which are to be at the bottom of the door, either or both of the grooves  10  and  11  at the bottom of the door may be used for the accommodation of weather stripping. 
     Following assembly of the core, the frame members, and the exterior panels the locking mechanism  28  and the knob  29  may be applied, if desired, or the assembly of these components may be deferred until such time as the door is received by its purchaser. The same observation applies to the application of hinges, weather stripping, and any other functional or ornamental apparatus. 
     A door constructed in accordance with the invention may be stored and shipped independently of any framing or, if desired, the door may be assembled with appropriate framing in the manner of any so called pre-hung door. 
     The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.