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BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The invention relates generally to hinged door assemblies which are mounted in an entry way. More particularly, the invention relates to a door assembly having skins secured to a frame. Specifically, the invention relates to a door assembly with a plurality of skins secured to a frame with protrusions, in a variety of skin arrangements, and a method of manufacturing the door. 
         [0003]    2. Background Information 
         [0004]    Doors are movable barriers used to cover an opening. A traditional household door can come in a variety of shapes and sizes depending on the desired look. However, the inner and outer skin of a door share the same profile, meaning that the design on the outside is the same as the design on the inside. 
         [0005]    A traditional hinged door is secured on one side to a door frame opening with hinges and secured to the other side with a locking mechanism. The frame may be comprised of four pieces, including a top and bottom rail secured between a hinge stile and a lock stile. The connection points of the frame may have dovetail joints machined in them so that the frame is a sturdy assembly. Skins are then secured to each face of the door frame assembly with an internal core separating these skins. The skins may be composed of fiberglass, wood, or any other suitable material, while the core may also be solid wood or a spray foam composite material. Traditionally, the back side of each skin is flush and adapted to receive an adhesive to secure the skin to the frame assembly. In order to assemble the door, the frame is assembled and one of the skins is secured to one side of the frame. Next, a foam core is inserted between the frame assembly and against the installed skin. Finally, the opposing skin is then glued to the open side of the door frame. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention broadly comprises a door including a frame having a plurality of slots, a first skin having a plurality of protrusions extending from a first skin back side, a second skin having a plurality of protrusions extending from a second skin back side, an adhesive disposed intermediate the frame and the first skin back side, and an adhesive disposed intermediate the frame and the second skin back side. 
         [0007]    The present invention also broadly comprises a door including a frame having a plurality of protrusions on a first side and a second side, a first skin and a second skin each having a back side with a plurality of slots, an adhesive disposed intermediate the first side and the first skin back side, an adhesive disposed intermediate the second side and the second skin back side, and wherein the first skin plurality of slots receive the first side plurality of protrusions and the second skin plurality of slots receive the second side plurality of protrusions. 
         [0008]    The present invention further broadly comprises a method of manufacturing a door including the steps of forming a plurality of slots in a frame, forming a plurality of protrusions on a back side of a first skin, applying a layer of adhesive on at least one of the frame and the skin, and inserting the plurality of protrusions into the plurality of slots. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0009]    A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
           [0010]      FIG. 1  is a front elevational view of the door assembly with a first skin mounted thereon; 
           [0011]      FIG. 2  is an exploded view of a preferred embodiment door assembly with the skins rotated in order to view the inside surface of each skin; 
           [0012]      FIG. 3  is a top plan view of the lock stile disconnected from the bottom and top rails; 
           [0013]      FIG. 4  is a front view of the lock stile showing vertical slots therein; 
           [0014]      FIG. 5  is a top plan view of the hinge lock stile disconnected from the top and bottom rails; 
           [0015]      FIG. 6  is a front view of the lock stile with vertical slots therein; 
           [0016]      FIG. 7  is a bottom view of a bottom rail with horizontal slots therein; 
           [0017]      FIG. 8  is a perspective view of a portion of the back side of a skin with a plurality of vertical protrusions extending from the back side of the skin; 
           [0018]      FIG. 9  is a front view of a portion of the top rail being slid downward and installed on the lock stile dovetail connection; 
           [0019]      FIG. 10  is a top view of a portion of the top rail secured to the lock stile with an adhesive; 
           [0020]      FIG. 11  is a top view of a preferred embodiment door assembly taken generally about line  11 - 11  in  FIG. 9  with the door skins removed; 
           [0021]      FIG. 12  is an assembled view of a preferred embodiment door assembly illustrated in  FIG. 11  with the door skins attached to the frame; 
           [0022]      FIG. 13  is an enlarged view of the section labeled  FIG. 13  in  FIG. 12 ; 
           [0023]      FIG. 14  is a perspective view of the top stile side of a preferred embodiment door in the fully assembled state; 
           [0024]      FIG. 15  is an exploded view of a second preferred embodiment door frame assembly with the skins rotated to show the door skin inner surfaces and a dual composite wood frame; 
           [0025]      FIG. 16  is a top cross-sectional view of a second preferred embodiment door with a dual composite frame; 
           [0026]      FIG. 17  is an exploded view of a third preferred embodiment door assembly with the skins rotated to show the inner surfaces of each skin; 
           [0027]      FIG. 18  is a cross-sectional view of a third preferred embodiment door frame assembly with door skins separated from the frame; and, 
           [0028]      FIG. 19  is a cross-sectional view of the door assembly in  FIG. 18  with the skins attached. 
       
    
    
       [0029]    Similar numbers refer to similar parts throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention as claimed is not limited to the disclosed aspects. 
         [0031]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of the ordinary skill in the art to which this invention belongs. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described. 
         [0032]    The door assembly of the present invention is indicated generally at  20 , and is particularly shown in  FIGS. 1-19 . As specifically seen in  FIG. 1 , a preferred embodiment door assembly  20  includes a first skin  22  with a variety of panels  24 . As seen in  FIG. 2 , door assembly  20  also includes a second skin  26  which is secured to the door frame  28  opposite first skin  22  and will be described in further detail below. 
         [0033]    Door frame  28  includes four components in a preferred embodiment. A lock stile  30  is parallel and spaced apart from a hinge stile  32 . The hinge and lock stiles define the vertical perimeter of the door and are preferably spaced apart approximately the same distance as the length of a top rail  34  and a bottom rail  36 . Lock stile  30  includes dovetail joints  38  extending from a top end  39  and a bottom end  41  to ensure a secure engagement with the top and bottom rails. Hinge stile  32  also includes dovetail joints  38  extending from a top end  45  and a bottom end  47 . 
         [0034]    In accordance with one of the main features of the present invention, a plurality of slots  40  is formed in both a front side  42  and a back side  44  of lock stile body  46 . In a preferred embodiment, slots  40  are formed in body  46  and extend vertically the full length of body  46 , however, it is within the spirit in the scope of the present invention as claimed that the slots extend for merely 25% of the height of the frame, 50% of the height of the frame, or any other suitable length. As seen in  FIGS. 3 and 4 , slots  40  include sidewalls  48  and a bottom wall  50  which define a generally rectangular opening. While the protrusion is preferably defined with a rectangular cross-section, any suitable cross-section may be incorporated, including semi-circular, square or any other shape. 
         [0035]    Moving on to  FIGS. 5 and 6  and in accordance with yet another main feature of the present invention, hinge stile  32  is arranged similar to lock stile  30 . Hinge stile  32  includes a plurality of slots  40  arranged vertically throughout the length of body  52  of hinge stile  32 . 
         [0036]      FIG. 7  is a bottom view of bottom rail  36 . Bottom rail  36  includes a pair of bottom slots  54  extending along the length of bottom rail  36 . Bottom slots  54  are preferably arranged to receive a door sill seal. Further, bottom rail  36  includes receiving portions  56  which are complimentary shaped to and arranged to contact the dovetail joint of the hinge and lock stiles. 
         [0037]    Referring to  FIGS. 2 through 6 , lock stile body  46  includes an inner wall  43  and hinge stile body  52  includes an inner wall  49 . Further, top rail  34  and bottom rail  36  each include inner walls  35  and  37  respectively. Advantageously, inner walls  35 ,  37 ,  43  and  49  define an internal cavity  75 . 
         [0038]    In accordance with yet another main feature of the present invention,  FIG. 8  illustrates first skin  22  with a back side  58  having a plurality of protrusions  60  extending therefrom. In a preferred embodiment, protrusions  60  are spaced a distance A from a top edge  62  of skin  22 . Further, a similar distance is incorporated for the bottom end of the skin (not shown). Advantageously, this arrangement allows the second skin back side  58  to be flush against top rail  34  and bottom rail  36  while allowing protrusion  60  to engage slots  40 . While a preferred embodiment second skin includes five protrusions, any number or arrangement of protrusions may be incorporated without departing from the spirit and scope of the present invention as claimed. Further, protrusions  60  are illustrated with generally square walls extending from the back side of the skin and a rounded top end. Protrusion  60  may have a varying width as well as any suitable shape so long as they mate with slots  40 . Finally, protrusions  60  are also spaced apart a distance B which can also be varied so long as the requirements above are satisfied. 
         [0039]      FIG. 9  illustrates top rail  34  being inserted in the direction of arrow  64  to install the top rail on frame  28  along top end  39 . An adhesive  66  is placed on inner wall  35  and receiving portion  56  to secure the top rail to lock stile  30 . A similar process is completed with respect to hinge stile  32  to secure the other side of top rails  34  to the hinge stile. While the adhesive is described as being placed on inner wall  35 , the adhesive may also be placed directly on the hinge and lock stiles. 
         [0040]      FIG. 10  is a top view of top rail  34  installed on dovetail joint  38  of lock stile  30 . In particular, dovetail joint  38  is slidingly engaged with receiving portion  56  of top rail  34 . Advantageously, this arrangement allows top rail  34  to be secured on lock stile  30  and permit movement only in an upward direction. 
         [0041]      FIGS. 11-13  illustrate the attachment of first skin  22  and second skin  26  to lock stile  30  as well as locating a foam core  68  between the skins in cavity  75 .  FIG. 11  illustrates skins  22  and  26  prepared for installation on lock stile  30 , while a similar arrangement is found at hinge stile  32 , but not shown. As discussed above, skin  22  includes a back side  58  with protrusions  60  extending away from the skin. The first skin  22  also has a front side  70  which includes a variety of panels as discussed above. Second skin  26  includes a back side  72  having a plurality of protrusions  60  extending therefrom and a front side  74  opposite back side  72  and also including a plurality of panels. 
         [0042]      FIG. 12  illustrates first skin  22  and second skin  26  in the installed position after forcing protrusions  60  within slots  40 . Specifically, skin  22  is forced in the direction associated with arrow  76  while skin  26  is forced in the direction associated with arrow  78 . In a preferred embodiment and seen in  FIGS. 12 and 13 , adhesive is located along the back side  58  of skin  22  and back side  72  of skin  26  such that adhesive bonds between the back sides  58 ,  72  and lock stile  30  and a top rail outer surfaces  29 A and  29 B. Further adhesive is also located within slots  40  and on protrusions  60  such that there is an increased adhesive area at the protrusions. During the installation, skins  22  and  26  are forced in their respective directions until protrusions  60  are fully seated within slots  40 . Protrusions  60  and slots  40  may also be arranged such that there is a slight interference fit to ensure that the skins do not become separated from the frame while the adhesive is curing. 
         [0043]      FIG. 14  illustrates the top corner of a preferred embodiment door assembly  20 . Top rail  34  is adhesively secured to lock stile  30 , while skins  22  and  26  are each adhesively secured to top rail  34  and lock stile  30 . Accordingly, the present invention creates a sounder and more secure bound between door skins  22  and  26  and lock stile  30  and hinge stile  32  (not shown) while retaining the traditional look of a standard door. 
         [0044]    Having described the structure of the first embodiment, only those portions of the second embodiment which are different than the first embodiment are described in detail. Likewise, similar numerals refer to similar parts throughout the various embodiments. 
         [0045]      FIGS. 15 and 16  illustrate a second preferred embodiment, with a first skin  80  and a second skin  82 . In accordance with yet another main feature of the present invention, skins  80  and  82  have distinct and different outer surfaces  84  and  86  respectively. Further, inner surfaces  85  and  87  of skins  80  and  82  are also distinct from each other. While the second preferred embodiment is shown with six panels  24  on the first skin and two panels  83  on the second skin, any arrangement of first and second skins that have a distinct outer appearance may be utilized. Advantageously, this allows the purchaser to have a first skin which matches the exterior of the dwelling, while having a second skin facing the interior of the dwelling that again matches a completely different environment than the outside. 
         [0046]    Another advantage of the preferred embodiments is the ability to selectively size the door using protrusions  60  and slots  40 . Specifically, protrusions  60  may align with only a portion of slots  40 , thereby having a portion of the skins hang over the frame. The skin can then be trimmed to reduce the side of the door. The hinge and lock stiles may then include an additional member bolted thereon to ensure a proper door size. 
         [0047]    In a second preferred embodiment, frame  88  is composed of six pieces, top rail  34  and bottom rail  36  remaining the same as the previous embodiment. However, lock stile  90  includes a high quality outer piece  92  and a low quality interior piece  94 . Hinge stile  96  also includes a high quality outer piece  98  and a low quality inner piece  100 . High quality pieces  92  and  98  both include dovetail joints at the top and bottom portions and define the outer most edges of the frame. High quality pieces  92  and  98  are also thin and incorporated at the ends to provide the appearance of a hard wood or high quality door throughout the frame construction, while reducing costs by incorporating low quality pieces  94  and  100 . Further, low quality pieces  94  and  100  include protrusions  40  similar to the first embodiment throughout their length. Advantageously, incorporating low quality pieces  94  and  100  for the entire length of the slots ensures that machining of the slots is more readily accomplished without a waste of material. 
         [0048]    Finally, high quality piece  92  is preferably adhesive secured to low quality piece  94 , while high quality piece  98  is also adhesively secured to low quality piece  100 . Accordingly, when the high quality and low quality pieces are attached, they form the lock stile and hinge stile described in the first preferred embodiment in a more cost effective manner. 
         [0049]    Having described the structure of the first two embodiments, only those portions of the third embodiment, which are different than the first two embodiments, are described in detail. Likewise, similar numerals refer to similar parts throughout the various embodiments. 
         [0050]      FIGS. 17-19  illustrate a third preferred embodiment with a first skin  102 , a second skin  104 , and a frame  106 . Frame  106  is generally shaped identical to the first preferred embodiment frame, however the incorporation of the second preferred embodiment frame with high quality and low quality pieces is within the spirit and the scope of present invention as claimed. Further, first skin  102  is arranged similar to first skin  22  in that there are six panels  24 . Second skin  104  has three panels  108  in the third preferred embodiment to provide a distinct and different appearance than the first skin. Frame  106  includes a lock stile  110  and a hinge stile  112 . 
         [0051]    In accordance with one of the main features of the present invention, lock stile  110  and hinge stile  112  (not shown) include a plurality of protrusions  114  extending from both sides of each stile. Further, skins  102  and  104  each include a back side  116  and  118  respectively. A plurality of slots  120  are formed within back sides  116  and  118  so that slots  120  are arranged to receive protrusions  112  of lock stile  110  and hinge stile  112 . 
         [0052]    As discussed in the first preferred embodiment, installation of the third preferred embodiment skins is similar in that first skin  104  is forced in the direction associated with arrow  122  until protrusions  114  are inserted within slots  120 , while the second skin is forced in the direction associated with arrow  124  until protrusions  114  are inserted within slots  120 . Once again, this arrangement provides for an increased adhesion contact area as well as an interference fit between the skins and the stiles. 
         [0053]    Having described the structure of the preferred embodiments, a preferred method of manufacturing will be described in detail and should be read in light of  FIGS. 1-19 . 
         [0054]    Initially, plurality of slots  40  are formed in frame  28 , and preferably in lock stile  30  and hinge stile  32 . Next, a plurality of protrusions  40  are formed on back side  58  and  72  of the skins. The slots may be formed by machining or any other suitable removable technique. Similarly, protrusions  60  may be formed by removing material with a machining apparatus or by adhesively securing preformed protrusions on the back side of each skin. Alternatively, slots  40  may be formed in the skins, while protrusions  60  may be formed on frame  28  without departing from the spirit of the invention. 
         [0055]    Next, adhesive is located on either frame  28  or back side  58  and  72  of skins  22  and  26 . The skins are then directed towards the frame such that the protrusions  60  are inserted within the respective slots  40  of the frame. After one side has been inserted, foam core  68  is disposed within the frame or may be placed by blowing foam insulation within the frame. 
         [0056]    Frame assembly  28  is formed by machining top rail  34  with receiving portions  56  on each end and bottom rail  36  with the same receiving portions  56 . Lock stile  30  and hinge stile  32  each include dovetail joints  38  on each end. The dovetail joints and receiving protrusions are complimentary shaped to ensure a tight and secure fit as well as provide increased contact surface for the adhesive to cure. Frame  28  is finally formed by securing the dovetail joints and receiving portions of the lock stile, hinge stile, top rail and bottom rail with adhesive. 
         [0057]    While the above method of manufacturing utilizes protrusions on the back side of each skin, it is within the spirit of the scope of the present invention to form protrusions on both sides of the lock and hinge stiles and machine slots in the back side of each skin. Further, a combination of the two may also be used without departing from the spirit of the scope of the invention as claimed. For example, one side of the lock stile may have protrusions, while the opposite side of the same stile may have slots therein. Still further, the lock stile may have protrusions on both ends, and a combination of protrusions and slots while the hinge stile only has slots. Thus, it is seen that any useful combination of slots and protrusions on the stiles and skins may be used without departing from the spirit and scope of the present invention as claimed. 
         [0058]    Thus, door assembly  20  provides an increased contact surface area between a door frame and the skins. The door skins are also arranged so that a first skin may have a unique and distinct outward appearance, while the opposing second skin may have a completely different appearance to enable the purchaser to custom fit his/her desired application. Further, a cheaper and more cost effective version of the invention may be incorporated by providing both high quality and low quality wood strategically placed to provide the increased contact surface as well as different skin options. 
         [0059]    It will be evident to one skilled in the art that a variety of changes can be made that are within the spirit and scope of the present invention. For instance, the protrusions may be located on either the skin or the stile, while the slots may also be located on either the skin or stiles. Further, any suitable skin design may be used in combination with any other suitable skin design such that the purchaser has a great deal of flexibility in his/her door skins. 
         [0060]    Accordingly, the door assembly is an effective, safe, inexpensive, and efficient device that achieves all of the desired objectives of the invention, provides for eliminating difficulties encountered with prior art devices, systems, methods, and solves problems and obtains new results in the art. 
         [0061]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0062]    Moreover, the description and illustration of the invention is an example, and the scope of the invention is not limited to the exact details shown or described. 
         [0063]    Having now described the features, discoveries, and principles of the invention, the manner in which the door frame is constructed and used, the characteristics of the construction, and the advantageous new and useful results obtained; the new and useful structures, devices, elements, arrangement, parts and combinations are set forth in the appended claims.

Summary:
A door including a frame having a plurality of slots on opposing sides, a pair of skins having a plurality of protrusions extending from a back surface, wherein the skin is secured to the frame with an adhesive between the skin and the frame as well as between the protrusions and slots. A method of manufacturing a door including the steps of forming a plurality of slots in a frame, forming a plurality of protrusions on a back side of a first skin, applying a layer of adhesive on at least one of the frame and the skin, and inserting the plurality of protrusions into the plurality of slots.