Abstract:
The present invention provides a door frame comprising of two piece units and the method of installment to provide connection between the casing and the frame with a self-alignment system. This is done by a tongue and groove connection and plurality of prefabricated dowels that are specially formed to engage the grooves provided in the frame through the entire attachment area of the frame units together. The door frame units are being assembled and secured together by providing a solid reinforced assembly. In the door frame system of the present invention a strong square joint can be produced by inserting dowels at critical joints which is significantly stronger fastening mechanism than other fastening means such as nails, staples, etc. Low expansion reinforced foam fills the cavities of the frame and creates a solid bond between door system and casing.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is a prefabricated door frame assembly and a method of installation for the same. 
       BACKGROUND OF THE INVENTION 
       [0002]    In order to reduce labor costs and time required to construct buildings such as homes and offices, various building mechanisms or assemblies, such as door assemblies, are prefabricated. Prefabrication avoids the need to transport many materials and skilled workers to the construction site, therefore, reducing time and cost. 
         [0003]    The prior art related to the prefabricated door assemblies discloses a partially assembled door frame. In order to fit the door frame within an irregular opening in a wall panel, casing members are generally supplied separately and are placed in the door opening. A certain amount of labor time is needed in order to properly mount the casing members. Once the casing and frame are set, the door is hung in its frame. 
         [0004]    A typical prefabricated door takes approximately 60-90 minutes for a skilled carpenter to install and involves shimming and attaching the door jamb to wall studs, attaching trim around the door opening to hide the gap between the jamb and the wall, and finally hinging the door to the jamb. 
         [0005]    There is a demand for more simplified and more economical building materials, components and techniques. One particular segment of the increased volume, which has exhibited widespread growth, is the field of home improvement where carpenters and builders seeking easier and foolproof procedures reducing time accomplish a great deal of the work and thus, reducing cost. In response to such demands, various modular door and frame assemblies, in which a good deal of the operations that require more skilled and specialized tools, are completed in the factory, leaving only less complex procedures to the installer in the field. 
         [0006]    The present invention provides a door assembly, which is completely prefabricated and does not require professionals to install the door frame and is basically a self-installing system. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is a completely prefabricated doorjamb system that is easy to install, takes less time to install, and does not require professionals for installation. 
         [0008]    The present invention provides a door frame comprising of two split units that are joined together forming a single frame, and a method of installment of the door frame on the wall opening. The present system has a tongue and groove connection means for self-alignment of the two split units. In addition, separate elements of each split unit are glued together and enhanced with a plurality of prefabricated dowels provided in the frame through the entire attachment area of the frame units. Strong square joints are produced by inserting dowels at critical joints. This provides a significantly stronger fastening mechanism than other fastening means such as nails, staples, etc. 
         [0009]    The door frame split units are attached to each other and to the wall opening using foams, glues or any other adhesives. Low expansion reinforced foam fills the cavities of the frame and creates a solid bond between door system and the wall. Traditional method of attachments, like using nails and screws, can also be used to attach the frame to the wall. 
         [0010]    The present invention does not require any attachment mechanism to support the door or tools for installation. It allows an unskilled laborer to install an interior door in a significantly less time than that required for installation of a conventional pre-hung door by a skilled carpenter. The tongue and groove alignment system makes it possible to install the door frame on varying wall dimensions with variation up to 0.75 inches to accommodate different drywall thickness and imperfections in the walls. There is no need for the installer to fasten the jamb to the wall or to square the legs and head of the jamb. 
         [0011]    It is the first objective of the present invention to provide a Complete Factory Finish door system. The installation system can be used by the home owners, to install their doors by themselves in a quick, easy and inexpensive way. It is a completely preassembled unit which stays securely in place and retains the integrity of its connecting joints by itself. 
         [0012]    It is the second objective of the present invention to provide a Self-Installing door system, which does not require a skilled worker for installation. 
         [0013]    It is another objective of the present invention to provide a door frame installation system which reduces the installation time and labor cost. The presently disclosed door system can be installed within 15 minutes, whereas the other prefabricated door frames may take an hour or more to complete. 
         [0014]    It is another object of the present invention to provide a stronger, tighter and more solid connection between different elements of the door assembly. 
         [0015]    Other objects, features, and advantages of the present invention will be readily appreciated from the following description. The description makes reference to the accompanying drawings, which are provided for illustration of the preferred embodiment. However, such embodiments do not represent the full scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Embodiments herein will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which: 
           [0017]      FIG. 1  is a perspective view of a free standing, prefabricated door/jamb assembly according to the present invention; 
           [0018]      FIG. 2  is a perspective view of the bottom portion of the door frame; 
           [0019]      FIG. 3  is a perspective side view of the front frame and back frame joint; 
           [0020]      FIG. 4  is a perspective view of the bottom of the front (female) frame; 
           [0021]      FIG. 5  is a perspective view of the bottom of the back (male) frame; 
           [0022]      FIG. 6  is a cross sectional view of a corner of the door frame; 
           [0023]      FIG. 7  is a bottom view of the door frame assembly and the door installed thereon; 
           [0024]      FIG. 8  is a partial perspective view of the door frame assembly and the door installed thereon; 
           [0025]      FIG. 9  is a sectional view of the first step of the installation of the frame on the wall opening; 
           [0026]      FIG. 10  is a sectional view of the second step of the installation of the frame on the wall opening; 
           [0027]      FIG. 11  is a sectional view of the third step of the installation of the frame on the wall opening; 
           [0028]      FIG. 12  is a sectional view of the fourth step of the installation of the frame on the wall opening; 
           [0029]      FIG. 13  is a sectional view of the fifth step of the installation of the frame on the wall opening; 
           [0030]      FIG. 14  is a sectional bottom view of a complete frame installed on the wall opening, and 
           [0031]      FIG. 15  is a front view of the upper corner of the frame. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]    The figures are not intended to be exhaustive or to limit the present invention to the precise form disclosed. It should be understood that the invention can be practiced with modification and alteration, and that the disclosed technology be limited only by the claims and equivalents thereof. 
         [0033]    The invention disclosed herein, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict typical or example embodiments of the disclosed technology. These drawings are provided to facilitate the reader&#39;s understanding of the disclosed technology and shall not be considered limiting of the breadth, scope, or applicability thereof. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale. 
         [0034]      FIGS. 1, 2 and 3  shows a prefabricated door frame unit  10  ready to be installed into an opening in the wall. The door frame unit  10  is fully pre-assembled. The door assembly  10  is comprised of two pieces of prefabricated U shape frames,  12  and  14 , each having an L shape cross section. A front (female) frame  12  and a back (male) frame  14 . The cross sections of the frames  12 - 14  comprise of a door jamb  12   a  and  14   a , and a side casing  12   b  and  14   b . The door jambs  12   a  and side casing  12   b  of the front frame  12  are connected to each other to build the L shape cross section door frames  12 . Similarly, and the door jamb  14   a  and the side casing  14   b  of the back frame  14  are connected to each other to build the L shape cross section door frames  14 . Connecting the two L shape sections  12  and  14  will result in a U shaped cross section. The door jambs  12   a - 14   a  comprise of a pair of vertical side legs  16 - 18  and a horizontal first header units  17 ,  19  crossing the upper ends of the side legs  16 - 18 . The side casings  12   b - 14   b  further comprise of vertical legs  22 - 24  and a horizontal casing header  25  crossing the upper ends of said vertical legs  22 - 24 . The frame units  12 - 14  are manufactured in any desirable length and in one-piece construction or the side casings and the door jambs can be manufactured in two separate pieces and connected together on installation site by dowel means. 
         [0035]    The side legs  16  and the first header  17  of the front frame  12 , and the side legs  18  and the second header  19  of the back frame  14  are sized to fit in the doorway and be securely maintained in a parallel relationship to each other and in a perpendicular relationship to the headers  17 ,  19 . 
         [0036]    The upper ends of the vertical legs  22 - 24  of casings  12   b - 14   b  are squarely connected to the opposite ends of the casing header  25  in a distance from the top of the vertical legs  22 - 24  with a dimension equal to the width of the side casing keeping the L shape of the frame. 
         [0037]    The front frame door jamb  12   a  has an inner edge  12   c  having a cut at a right angle (90 degrees) on its top surface to build an longitudinal tongue trim extending all-around the inner edge  12   c  of the door jamb  12   a.    
         [0038]    According to  FIGS. 3 and 4  a door stop  20  is attached to the inner side of the front frame  12 . The door stop  20  includes vertical legs,  21  and top piece  23  crossing the upper end of the vertical legs  21 . Each of vertical legs of the door stop  21  form a square butt-end joint with top piece  23 . The door stop  20  is sized to fit on top surface of the front frame  12  and is attached on the front frame door jamb  12   a  close to its inner edge  12   c  in a manner that each door stop vertical leg  21  builds a groove  30  on the inner edge of the front door jamb  12   c.    
         [0039]      FIG. 4  is a view of the bottom  11  of the front frame  12  showing an elongated groove  30  formed in one edge of the front frame  12  extending all-around said edge. The grooved edge is a rectangular groove  30  having a planar lower surface  15  with a length same as the planar lower surface of the tongue in the back frame  14  and will engage to the back frame  14 . The groove is moulded so that a vertical leg  21  of the door stop  20  and a vertical leg  16  of the front frame  12  build the groove slot  30 . The inner side of the door stop legs  21 ,  22  build one angle of the groove which is preassemble glued or curved to the inner side of the front frame  12  facing the door opening  31 . 
         [0040]      FIG. 5  is a view of the bottom of the back frame  14  showing an elongated tongue  32  formed on inner edge  14   c  of the door jamb  14   a  of the back frame  14  extending all-around the edge  14   c . The tongue is a rectangular cut  32  from its bottom surface to build a longitudinal tongue trim  32  having a planar lower surface  13  with a length same as the planar lower surface of the groove  30  in the front frame  12 . The tongue trim  32  extends all-around the inner edge of male door jamb  14   c.    
         [0041]    As shown in  FIGS. 2 and 3  in installation the longitudinal tongue  32  of the back male frame  14  being received by the longitudinal groove  30  of the female frame  12  so that the front frame  12  and the back frame  14  being connected to each other securely. The tongue-and-groove units will join by projecting the front frame  12  to the front side of the doors opening and fit the back frame  14 , edge to edge, and allow two pieces  12 ,  14  to be joined strongly together to make a single frame unit  10  and providing substantial structural strength of the frame parallel to the wall. 
         [0042]    According to  FIGS. 1-8  plurality of dowel joints  36  in critical joinders are provided to support and maximize strength and rigidity of the frame 
         [0043]    The door frame unit  10  of the present invention is manufactured in two split units  12  and  14 , with a standard dimension and are adjustable up to 0.75 inches in depth. This allows for the installment of the present door assembly into a wide range of drywall thicknesses and imperfections in the wall. Therefore, there is no need to custom cut the door frame to a particular door opening, providing a custom fit door without customization. The prefabricated doors may be made from different types of wood, plastic, steel, fibreboard, or any other types of suitable material, and come in different colours and shades. 
         [0044]    The present door frame is prefabricated and ready for installation. In such prefabricated frames, the structural strength is critical. Therefore, it is important to use strong material, which provides sufficient lateral stability and resistance to shear forces in either direction. For this purpose, layers of plywood board are moulded and glued together to build a strong door frame with a tongue and groove attachment means. The tongue (male unit) fits the groove (female unit) tightly holding the two parts of the frame together. 
         [0045]      FIG. 7  shows the assembled door frame  10  from bottom side illustrating important refinements of the invention which shows the joint of the front frame  12  and back frame  14  to each other and create a door frame that is sufficiently rigid to support a door  40  without anchoring the frame to the wall. Said two adjacent frame units  12 ,  14  are connected together with a tongue-and-groove joint  30 ,  32  said tongue-and-groove joint being formed by projecting the front frame  12  to the front side of the doors opening and fit the back frame  14 , edge to edge, and allow two pieces  12 ,  14  to be joined strongly together to make a single frame unit  10  and providing substantial structural strength of the frame parallel to the wall. Plurality of dowel means  36  are provided to support and secure the units  12 ,  14  in relation to each other. It is determined that combination of dowels  36  and tongue and groove joint are used in critical joinder to maximize strength and rigidity to the frame. 
         [0046]      FIG. 8  is a sectional view of the assembled door frame  10  from its top. Dowels  36  secure corner joints. A door  40  is attached via hinges  42  to the Front frame  12 . The door is hinged to the vertical leg  22  of the side casing  12   b  of the front frame  12 . In order for a door frame to be strong enough to support a door without attachment to the wall, it is important that the corners be square, and the mechanism of the joint be strong enough to keep the structure of the door by daily pressures. The corner edges are secured together by the dowel pins  36 . The dowels  36  are intended to be formed therein by compression, in which a portion of the dowel is inserted and secured. The tongue and groove alignment system makes it possible to install the door frame  10  on varying wall dimensions with variation up to 0.75 inches to accommodate different drywall thickness and imperfections in the walls. There is no need for the installer to fasten the door frames to the wall or to square the legs and head of the frames. 
         [0047]    According to  FIGS. 6, 7 and 8 , again each of the side legs of the front frame  12  and side legs of back frame  14  are securely maintained in a parallel relationship to each other and in a perpendicular relationship to the headers  17  and  19  to form rigid metered corner joints. Corner joints are secured by dowels  36 . The corner sections are connected to one another, so that each frame part at the corner has a dowel extending outwardly thereof, and the corresponding frame member has an opening wherein the dowel extends into the depth of the opening by providing a force to securely connect the two corner joints to one another. The dowel members  36  insert completely into the depth of the corresponding frame corner and for engaging two corners a pressure force engagement is used to join the corners rigidly. 
         [0048]    The frame units  12  and  14  are usually being formed of wood boards but they may be formed of any suitable material. The board is fed through a grooving machine and adhesive preparation is inserted to make a firm, secure and supportive joints. 
         [0049]      FIGS. 9 to 15  disclose the assembly steps of the front frame  12  and back frame  14  for joining and being mounted to the door opening. In the first step as shown in  FIG. 9  the front frame (groove unit)  12  is mounted on the wall  50 . Usually adjustment to the guides as shown in  FIG. 10  step  2 , is done by inserting thin shims  51  between the frame units  12  and the wall  50  to align and make them fit. 
         [0050]      FIG. 11  step  3  shows the step of the joint of the frame units  12  and  14  in which foam  52  is applied between wall  50  and the frame units  12  and  14  to fill the gaps. The reinforced foam  52  provides strong resistance to forces exerted to the frame such as the forces applied to the frame by a door in the closed position. It is desirable to let for approximate 10-15 minutes to dry and then place the back frame (tongue unit)  14 . The tongue and groove units are moulded such that the tongue is fully inserted in to the groove and are cut in a standard dimension to have maximum width of the wall. 
         [0051]      FIGS. 12 and 13  in step  4  and  5  shows the front  12  and back frame  14  fully joined and secured to the wall opening.  FIG. 14  is a bottom view of a complete installed frame on the wall and  FIG. 15  shows the installed door frame unit according to the present invention. 
         [0052]    The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 
         [0053]    With respect to the above description, it is to be realized that the optimum relationships for the parts of the invention in regard to size, shape, form, materials, function and manner of operation, assembly and use are deemed readily apparent and obvious to those skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.