Abstract:
A door assembly is disclosed that includes a latch-side stile with bores for accommodating one or more bolts that extend through the stile and into an adjacent doorjamb to secure door with respect to the doorjamb. A reinforcing plate is mounted on the inner edge of the latch-side stile with flared flanges extending into the stile bores to hold the plate in place and to make it more difficult to force the door open by kicking the door in the area of its latch and lock. A method of assembling a door including such a reinforcing plate is also disclosed.

Description:
[0001]    This application claims the benefit of provisional application 60/261,186 filed Jan. 16, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed toward a method and apparatus for strengthening the frame of a door, and, more specifically, toward a device mounted inside a hollow-core door to reinforce a portion of the door stile in the vicinity of openings that accommodate locking or latching hardware.  
         BACKGROUND OF THE INVENTION  
         [0003]    Doors have traditionally been formed from solid pieces of wood. As wood has become increasingly expensive, alternative types of doors have become more common. One such alternative door is formed by two parallel vertical stiles connected by top and bottom rails to form a rectangular frame and two thin panels or door skins attached to the frame to form a door with a hollow-core. Such doors are lighter than solid wood doors, have a lower material cost, and, if the space between the door skins is filled with a suitable insulating material, may provide better thermal insulation.  
           [0004]    A first pair of aligned openings is provided in the door skins to receive a door handle or latching assembly and, optionally, a second pair of openings may be provided to accommodate a deadbolt or other lock. Latch bores extend through the stile next to these openings to allow a live bolt and/or a deadbolt to pass through the stile and into a corresponding opening in a doorjamb adjacent the latch side of the door. Optionally, a lock block with bores aligned with the door skin openings may be attached to the stile inside the door next to the latch bore to provide a secure mounting location for the door handle and lock hardware.  
           [0005]    Drilling latch openings though a stile weakens the stile significantly, and it is known that doors may be forced by delivering a sharp kick or otherwise applying a force in the area of the latch bore to split the wooden stile. This weakening occurs even when a solid piece of a sturdy wood is used; with lighter woods, such as sometimes used in hollow-core doors to reduce weight, the problem is even more significant. When an ordinary door is kicked near the lock assembly, the metal strike plate in the doorjamb holds the distal end of the door bolt relatively securely while the door is forced slightly inwardly. As the door moves, the latch or bolt pivots within the bore, and if a great enough force is applied, snaps the stile near the latch bore. Once the end of the bolt inside the door begins to pivot, it can act as a lever to pry the strike plate out of the doorjamb when further force is applied to the door. If a first kick does not completely open the door, the latch will be damaged enough to allow some play and let the door move back and forth. Weakened in this manner, it is highly likely that a subsequent kick will completely break the bolt from the door and allow the door to be opened.  
           [0006]    This problem has been recognized, and various attempts have been made to address it. For example, it is known from U.S. Pat. No. 5,586,796 to provide metal plates on the inside and outside faces of a door to reinforce the area around the lock and latch. While this approach does provide some additional strength, it also adversely affects the appearance of a door, giving it a commercial or industrial look. Alternately, U.S. Pat. No. 4,832,388 shows the use of unusually long screws for securing a strike plate to a doorjamb and for securing a reinforcing plate to the outer edge of the door, the screws being installed at an angle to the door and the doorjamb to make them more difficult to remove by force. However, this method requires that a large mortised region be formed on the outside edge of the door to accommodate the reinforcing plate. Moreover, because the reinforcing plate will be visible when the door is open, the plate should be made from a material with a finished appearance that matches the other door hardware, adding to the cost of the door. Furthermore, the oversized reinforcing plate may not be as aesthetically pleasing as the smaller plates that generally surround the live bolt of a door.  
           [0007]    It would therefore be desirable to provide a reinforcement for a door that is economical to produce and install, that can be sold as an integral part of a hollow-core door, and that can be used without affecting the outward appearance of a door.  
         SUMMARY OF THE INVENTION  
         [0008]    These problems and others are addressed by the present invention which includes a reinforcing plate mounted inside a door frame on the inner edge of the stile through which latch bores are drilled. In a preferred embodiment, the plate includes an opening aligned with each bore in the stile so that a live bolt or deadbolt can pass therethrough. When the door is closed and the bolt is extended, the bolt also extends though a strike plate mounted on a doorjamb and into an opening in the doorjamb. In one embodiment, the plate includes a flange surrounding each opening which flange extends into each bore to reinforce the bore and the stile. The flange preferably has at least one portion that is wider than the bore into which it is placed and may have outwardly flared or barbed end edges to help secure the plate to the stile. Alternately, or in addition, the plate may be dimpled or punched at locations spaced from the openings to form protrusions that extend into the stile to help secure the plate.  
           [0009]    In a second embodiment, the plate is provided with several groups of screw holes arranged in circular regions lying on either side of each of the plate openings along the longitudinal centerline of the plate. When a latch plate is installed on the outer edge of the latch stile of a door incorporating the subject reinforcing plate, longer-than-usual screws are used to attach the latch plate to the stile, which screws extend thought the stile and pass through one of the screw holes in the plate and into the body of the lock block.  
           [0010]    The plate in the door assembly of the preferred embodiment of the present invention provides support for a section of the bolt inside the door, away from the doorjamb. Thus, if a forced entry is attempted, the bolt is less likely to pivot in the door, and an intruder will essentially need to press the bolt, the reinforcing plate and the strike plate in a direction normal to the plane of the door to obtain entry. Because the reinforcing plate is securely mounted to the stile and the strike plate is secured to the doorjamb, a significant effort will be required to force the door open. While enough force will break any door, the present invention makes it appreciably more difficult to break down a door in the above-described manner.  
           [0011]    Preferably, the subject plate is press-fitted to the inner edge of the stile while the door is being manufactured and thus does not require separate fasteners or adhesives to hold it in place. Furthermore, because the plate is inside the door, there is no need to provide a mortise to accommodate the plate and keep it flush with another surface. Also, because the plate is hidden after it is installed, it can be formed from an unfinished sheet of material, and the same material can be used on any door without regard for its outward appearance.  
           [0012]    It is therefore a principal object of the present invention to provide a method of reinforcing a door that does not affect the outward appearance of the door.  
           [0013]    It is another object of the present invention to provide an internally mounted reinforcing plate for a door stile.  
           [0014]    It is another object of the present invention to provide a reinforcing plate that can be press-fitted to a frame of a door during manufacture.  
           [0015]    It is yet another object of the present invention to provide a reinforcing plate having at least one flanged opening that is received in a latch bore in a door stile for reinforcing the stile.  
           [0016]    It is yet a further object of the present invention to provide a method of reinforcing the frame of a door having more than one latch bore for accommodating more than one bolt.  
           [0017]    In accordance with these objectives, a door is disclosed that includes a first stile having a front wall, a rear wall, an inner wall, and an outer wall; a second stile parallel to and spaced from the first stile and including an inner wall facing the first stile inner wall; a first door skin connected to the first stile and to the second stile; a second door skin connected to the first stile and to the second stile; a first lock bore extending through the first door skin and the second door skin; and a first latch bore extending from the first lock bore through the first stile inner wall and the first stile outer wall. The door also includes a reinforcing plate connected to the first stile inner wall having a first opening aligned with the first latch bore.  
           [0018]    A method of forming a reinforced door is also disclosed, which method comprises the steps of: 1) taking a frame formed from first and second parallel side stiles having facing inner walls, a top rail connected between the first and second stiles and a bottom rail connected between the first and second stiles, 2) forming a latch bore having a diameter through the first stile, 3) taking a reinforcing plate including a flanged opening having a width greater than the first diameter and aligning it with the latch bore and pressing the flange into the latch bore until the plate contacts the stile and then attaching first and second door skins to the frame.  
           [0019]    Another embodiment of a door according to the present invention includes a door frame having a latch stile, a hinge stile, and a top rail and a bottom rail connected between the latch stile and the hinge stile, the latch stile having an inner wall facing the hinge stile and a latch bore though the inner wall. A reinforcing shield has an opening with a flange with a first portion of the flange having a width greater than the width of the latch stile latch bore extends into the latch stile latch bore. A reinforcing shield overlies the latch stile inner wall and includes at least one projection extending into the latch stile at a location spaced from the latch stile latch bore. A lock block has a lock bore connected to the latch stile inner wall and has a lock block latch bore aligned with the latch stile latch bore. First and second door skins are connected to the door frame and having openings aligned with the lock bore. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    These and further objects and advantages of the invention will be better understood after a reading of the following detailed description of the invention together with the following drawings.  
         [0021]    [0021]FIG. 1 is a side elevational view, with a portion broken away, of a door assembly including a reinforcing plate according to the present invention.  
         [0022]    [0022]FIG. 2 is a top plan view of the reinforcing plate of FIG. 1.  
         [0023]    [0023]FIG. 3 is a cross sectional view taken along line  3 - 3  of FIG. 2.  
         [0024]    [0024]FIG. 4 is an enlarged detail of a portion of FIG. 3.  
         [0025]    [0025]FIG. 5 is a cross sectional view taken along line  5 - 5  of FIG. 1.  
         [0026]    [0026]FIG. 6 is a cross sectional view taken along line  6 - 6  in FIG. 1.  
         [0027]    [0027]FIG. 7 is a top plan view of a second embodiment of a reinforcing plate according to the present invention.  
         [0028]    [0028]FIG. 8 is a sectional view of a door incorporating a latch plate and the reinforcing plate of FIG. 7 positioned adjacent a door jamb.  
         [0029]    [0029]FIG. 9 is a flow chart showing a method of assembling the door assembly of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    Referring now to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, FIGS. 1 and 6 show a door  10  comprising a door frame  12  including a latch stile  14 , a hinge stile  16 , upper and lower rails  18  connecting the latch stile to the hinge stile and two door skins  20  connected to opposite sides of door frame  12  in a well known manner. (“Upper,” “lower” and other directional terms used herein refer to a door positioned in a normal vertical orientation.) As best seen in FIG. 5, latch stile  14  has an inner wall  22 , an outer wall  24 , an upper latch bore  26  and a lower latch bore  28  extending though the stile between inner wall  22  and outer wall  24 . A lock block  30  is attached to latch stile  14  in a conventional manner, such as by staples, screws, bolts, fasteners, glue, etc. (not shown) and includes a lower opening  32  for receiving hardware associated with a door latch (not shown) and an upper opening  34  for receiving an auxiliary lock, such as a deadbolt, the bolt portion  35  of which is shown in phantom lines in FIG. 5. A lock block upper latch bore  36  extends from upper opening  34  though a side wall of the lock block while a lock block lower latch bore  38  extends from lower opening  32  through the lock block side wall. Door skins  20  are provided with an upper pair of aligned openings  40  that align with upper opening  34  in the lock block and a lower pair of aligned openings  42  that are aligned with lower opening  32  in the lock block. The door may also include insulation  44  of any conventional type, such as foam insulation.  
         [0031]    Door  10  further includes a reinforcing guard or plate  50 , shown separately from door  10  in FIGS.  2 - 4 , that is preferably formed from 0.035 inch thick galvanized steel, which plate includes a front face  52 , a rear face  54 , top and bottom edges  56 , side edges  58 , an upper hole  60  and a lower hole  62 . The distance between the side edges  58  is approximately equal to the width of the stile to which the plate will be attached as shown in FIG. 6. The upper and lower holes are centered between the side edges  58  and located near the top and bottom edges of the plate and are formed in a manner that produces flanges  64  around both openings extending from rear face  54  of the plate. Furthermore, the flanges are provided with outturned end edges  66 . These outturned end edges bite into the wood of latch stile  14  to help hold plate  50  in place as will be described hereinafter and, as the sharp edges point away from the centerline of the holes, the risk that a person installing hardware though the plate will come into contact with these sharp edges is reduced. Dimples  68 , as best shown in FIG. 5, are formed in plate  50  after it is attached to stile  14  by pressing a diamond-shaped tool into the plate to deform the plate and force portions of the plate into the stile  14 . These dimples, together with the force fit of the flanges in the bores in the latch stile, securely hold plate  50  in place without the use of adhesives or additional hardware.  
         [0032]    Referring again to FIG. 5, a portion of door  10  is shown positioned adjacent to a doorjamb  70  which doorjamb includes an upper bolt opening  72  surrounded by an upper strike plate  74  and a lower bolt opening  76  surrounded by a lower strike plate  78 . When door  10  is closed, upper bore  26  aligns with upper bolt opening  72  and lower bore  28  aligns with lower bolt opening  76 . Bolt  35  is shown extending from upper opening  34  through lock block upper latch bore  36 , reinforcing plate upper hole  60 , upper latch stile bore  26 , strike plate  74  and into opening  72  in the doorjamb. A live latch bolt would extend through the lower latch stile bore into the doorjamb in a similar manner.  
         [0033]    An attempt to force open door  10  would likely involve the application of a sharp force to the area of the door between openings  40  and  42  in the door skins. Such a force applied to an un-reinforced door would likely cause bolt  35  to twist in upper bore  26  and shatter the wood of latch stile  14  which is relatively thin in the area around the latch bores. Reinforcing plate  50  secures bolt  35  against such twisting, so that bolt  35  can only move normally to door skins  20  under the application of a force normal to the surface of the door. In order to forcibly open a door including a reinforcing plate  50 , the bolt would have to press against reinforcing plate  50  and strike plate  74  and move them directly out of the page as seen in FIG. 5. This would require substantially more force than would be required to pivot bolt  35  and split the wood of stile  14  of an un-reinforced door, because the flanges  64  and dimples  68  substantially prevent face  58  of the plate from sliding relative to inner wall  22  of stile  14 .  
         [0034]    A method of assembling a door that includes a reinforcing plate  50  will now be described with reference to FIG. 7. This method includes the steps of providing a door frame having a latch stile, a hinge stile and top and bottom rails connecting the stiles, forming at least one latch bore through the latch stile having a diameter, providing a reinforcing plate having a flanged opening with an outturned free end larger than the diameter of the latch stile bore, aligning the flange with the latch stile bore and pressing the flange into the latch stile bore until the flat portion of the plate contacts the stile, and then, optionally, pressing a tool against the flat portion of the plate to form dimples extending into the stile, then attaching a lock block over the reinforcing plate and attaching door skins to the door frame.  
         [0035]    A second embodiment of a reinforcing plate according to the present invention is shown in FIGS. 7 and 8 wherein elements identical to elements of the first embodiment are identified with the same reference numerals and wherein elements of the alternate reinforcing plate that correspond to elements of the reinforcing plate of the first embodiment are identified with like reference numerals and primes. In this embodiment, reinforcing plate  50 ′ includes a plurality of screw holes  80  arranged in generally circular groups  82  on either side of holes  60 ′ and  62 ′ in the plate along the longitudinal midline of the plate. The screw holes are preferably about ⅛ inch in diameter and the diameter of the circular groups is about ½ inch, so that very little space is left between the screw holes. Plate  50 ′ is installed against latch stile  14  in the same manner as the reinforcing plate of the first embodiment. However latch stile  14  is provided with a latch plate  84  which includes a first opening  86  that surrounds upper bore  26  in the latch stile and a second opening  88  that surrounds lower bore  28  in the latch stile. Latch plate  84  also includes openings  90  adjacent openings  86  and  88  for receiving fasteners such as screws  92  to secure the latch plate to the latch stile. Normally, a latch plate would be attached to a latch stile using a ⅝ or ¾ inch screw, but in this embodiment, screws  92  are at least about 1⅜ inches long so that they will extend though the stile and reinforcing plate and into the lock block.  
         [0036]    A door including reinforcing plate  50 ′ is assembled in the manner described above and then latch plate  84  is positioned on the outside of the latch stile with latch plate opening  86  aligned with upper bore  26 . Each of openings  90  in the latch plate is located directly opposite latch stile  14  from one of the circular groups  82  of screw holes  80 . When a screw  92  is inserted through the latch plate and driven through the latch stile, its leading end will engage one of the plurality of holes in one of the groups of holes and pass through that hole and into lock block  30 . This arrangement helps anchor the lock block securely to the latch stile and holds reinforcing plate  50 ′ very securely between these two elements, even when a forced entry is attempted.  
         [0037]    The present invention has been described above in terms of a preferred embodiment. Modifications and additions to this embodiment will become apparent to those skilled in the art upon a reading and understanding of the above description and the accompanying drawing figures. For example, the reinforcing plate is shown as having two openings, but could just as easily have a single opening for use in situations where a deadbolt is not present, or three or more openings where the number of bolts extending though the stile so requires. It is intended that all such obvious modifications and additions be covered by this application to the extent that they are included within the scope of the several claims appended hereto.