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FIELD OF INVENTION  
         [0001]    The present invention relates to a fire retardant panel door, and more particularly to a reinforced fire retardant panel door that provides additional structural support, stiffness and fire resistance for preventing the spread of fire through the fire retardant panel door and door frame.  
         BACKGROUND OF THE INVENTION  
         [0002]    A fire retardant panel door, often referred to as a “fire door,” is installed in homes, commercial buildings, and industrial plants for preventing the passage or spread of fire from one part of the building to another. In the interest of public safety, standards have been set by governmental agencies; and by municipal, county and state building code authorities and insurance companies for the installation and performance of fire doors. The standards require that the fire retardant doors be installed in wall openings and that they pass industry-wide acceptance tests.  
           [0003]    Standard test methods for fire door assemblies, such as ASTM E-152, UL 10(b) or NFPA 252, measure the ability of a door assembly to remain in an opening during a fire to retard the passage of the fire and evaluate the fire resistant properties of the door. In conducting such tests, doors are mounted in an opening of a fire proof wall. One side of the door is exposed to a predetermined range of temperatures over a predetermined period of time, followed by the application of a high pressure hose stream that causes the door to erode and provides a thermal shock to the assembly. Doors are given a fire rating based on the duration of the heat exposure of 20 minutes, 30 minutes, 45 minutes, one hour, 1½ hours or three hours. The door assembly receives the fire rating when it remains in the opening for the duration of the fire test and hose stream, within certain limitations of movement and without developing openings through the door either at the core or around the edge material.  
           [0004]    A fire door must be made almost entirely of incombustible material. However, since a fire door is part of the interior or exterior of a personal living space or workspace, it must also be aesthetically pleasing. Usually, therefore, a core of incombustible material comprising the main structure of the fire door is overlaid with a thin wood veneer facing that provides the door with an attractive appearance. Fire door assemblies often fail, not because of the fire resistant properties of the fire door, but they fail because of inadequate structural strength of the door such that the fire door buckles. Additionally, the fire resistant blocking material of a core section of the fire door may need supplemental fire resistant materials strategically placed within the fire door to add to its fire door rating.  
           [0005]    There remains a need for a reinforced fire retardant panel door which provides additional structural support, strength and stiffness to the fire retardant panel door in order to prevent buckling of the fire retardant panel door during a fire. Further, the reinforced fire retardant panel door would include supplemental fire resistant materials strategically embedded within the structural components of the fire retardant panel door.  
         DESCRIPTION OF THE PRIOR ART  
         [0006]    Fire retardant doors, and fire doors of various designs, configurations, structures and materials of construction have been disclosed in the prior art. For example, U.S. Pat. No. 6,115,976 to Gomez discloses an assembly for sealing a fire resistant door within a door frame during a fire event. The door edge assembly includes a plurality of door edges for receiving an intumescent strip within a slot on each door edge. The intumescent strip is constructed and designed to expand upon reaching a certain reaction temperature when exposed to a fire event or other extreme heat source. This prior art patent does not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire, as well as prevent the spread of fire through the door and door frame for at least 90 minutes.  
           [0007]    U.S. Pat. No. 5,816,017 to Hunt et al. discloses a fire retardant door and exit device for the fire retardant door. The fire retardant door includes a core of fire resistant blocking material being Tectonite™ for providing the door with a fire rating of at least 90 minutes. The fire door uses intumescent material which expands when heated to fill the void in the channel between the channel walls and the vertical extending rods within the latch stile of the door. This prior art patent does not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire, as well as prevents the spread of fire through the door and door frame.  
           [0008]    U.S. Pat. No. 5,417,024 to San Paolo discloses a fire resistant panel door. The fire resistant panel door is constructed from panels, stiles, mullion and rails having a core of fire resistant material. The door components are joined together so that the fire resistant material extends substantially continuously from side to side and from top to bottom of the finished door. The fire resistant core of each door panel is recessed within the fire resistant core of the associated rails and stiles to reduce air infiltration through the door which can compromise the door&#39;s fire resistance. This prior art patent does not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire.  
           [0009]    U.S. Pat. No. 4,930,276 to Bawa et al. discloses a fire door window construction. The fire door includes a trim strip having inner and outer members. The inner member is of a high density incombustible mineral material or ceramic and is nailed in position to securely and uniformly hold the pane of glass in the door opening. The outer trim member is of a fire retardant particle board and has an exposed wood veneer facing throughout. An intumescent caulking compound is applied between an inner portion of the outer trim member and the pane of glass. This prior art patent does not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire, as well as prevents the spread of fire through the door and door frame for at least 90 minutes.  
           [0010]    U.S. Pat. No. 4,441,296 to Grabendike et al. discloses a fire resistant wood door structure designed to pass code and testing laboratories&#39; requirements. The fire resistant wood door structure includes a door assembly having a support frame assembly with a panel assembly connected to the support frame assembly. The support frame assembly includes top, bottom, side, central and transverse frame members. The panel members include a main body connected through a peripheral edge by a double connector assembly. The double connector assembly functions to only remove about ⅓ of the door&#39;s normal 1¾ inch thickness during the burn testing procedure, thus passing the fire resistant testing of 20 minutes. This prior art patent does not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire, as well as prevents the spread of fire through the door and door frame for at least 90 minutes.  
           [0011]    U.S. Pat. Nos. 4,529,742; 6,031,040; and 6,153,674 all disclose the use of intumescent compounds/fire barrier materials within door construction to reduce or eliminate the passage of smoke and fire through the door and door frame. These prior art patents do not disclose or teach the particular door structure having steel insert washers and having steel joint plates for door reinforcement, nor the use of intumescent material in the door joints in order to provide for a reinforced fire retardant panel door that prevents buckling of the door during a fire, as well as prevents the spread of fire through the door and door frame for at least 90 minutes.  
           [0012]    In addition, the aforementioned prior art patents do not disclose or teach the particular structure and configuration of the reinforced fire retardant panel door of the present invention that provides additional structural support, strength and stiffness to the door in order to prevent the buckling of the door during a fire.  
           [0013]    Accordingly, it is an object of the present invention to provide a reinforced fire retardant panel door that prevents buckling of the door during a fire.  
           [0014]    Another object of the present invention is to provide a reinforced fire retardant panel door that has additional structural support, strength and stiffness with the use of a plurality of joint steel washers and a plurality of joint steel plates which are embedded within the fire resistant blocking material (core section) of the door for preventing the buckling of the fire door during a fire.  
           [0015]    Another object of the present invention is to provide a reinforced fire retardant panel door that has supplemental fire resistant materials strategically embedded and placed within the tongue and groove joints of the fire resistant panel door, as well as supplemental fire resistant materials placed on the perimeter edges of the fire resistant panel door for preventing the spread of fire through the door and door frame.  
           [0016]    Another object of the present invention is to provide a reinforced fire retardant panel door that has fire resistant materials being intumescent material that expands in the presence of fire such that the intumescent material closes and seals the component tongue and groove joints, as well as the perimeter edges of the fire retardant panel door for preventing the spread of fire through the door and door frame.  
           [0017]    Another object of the present invention is to provide a reinforced fire retardant panel door that is used as part of an interior or exterior personal living space, or workspace being installed within home dwellings, commercial buildings or industrial plants.  
           [0018]    Another object of the present invention is to provide a reinforced fire retardant panel door that is aesthetically pleasing having the appearance of natural wood, and has achieved a successful fire rating of at least 90 minutes and passes a positive pressure test, and is easily installed in a building.  
           [0019]    A further object of the present invention is to provide a reinforced fire retardant panel door that can be mass produced in an automated and economical matter and is readily affordable to the builder or consumer.  
         SUMMARY OF THE INVENTION  
         [0020]    In accordance with the prevention, there is provided a reinforced fire retardant panel door that prevents buckling of the door during a fire. The reinforced fire retardant panel door includes a door having at least one door panel and stiles and rails. The reinforced fire retardant panel door also includes at least four (4) steel washer inserts embedded within the door for reinforcing the connection between the door panel and the stiles and rails. Further, the reinforced fire retardant panel door includes at least four (4) steel joint plates embedded within the door member for reinforcing the connection between the stiles and rails for providing increased structural strength and stiffness to the door in order to prevent buckling of the fire retardant panel door during a fire. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    Further objects, features and advantages of the present invention will become apparent upon the consideration of the following detailed description of the presently-preferred embodiment when taken in conjunction with the accompanying drawings, wherein:  
         [0022]    [0022]FIG. 1 is a front perspective view of the reinforced fire retardant panel door of the preferred embodiment of the present invention showing its major component parts thereof;  
         [0023]    [0023]FIG. 2 a  is a cross-sectional view of the reinforced fire retardant panel door of the present invention taken along lines  2   a - 2   a  of FIG. 1 in the direction of the arrows showing a pair of joint plates connecting a stile to an upper rail and a lower rail and a joint washer;  
         [0024]    [0024]FIG. 2 b  is a cross-sectional view of the reinforced fire retardant panel door of the present invention taken along lines  2   b - 2   b  of FIG. 1 in the direction of the arrows showing a pair of joint washers connecting the right panel to the upper rail and the lower rail, respectively;  
         [0025]    [0025]FIG. 3 a  is a cross-sectional view of the reinforced fire retardant panel door of the present invention taken along lines  3   a - 3   a  of FIG. 1 in the direction of the arrows showing a pair of joint washers connecting the upper rail to a pair of panels;  
         [0026]    [0026]FIG. 3 b  is a cross-sectional view of the reinforced fire retardant panel door of the present invention taken along lines  3   b - 3   b  of FIG. 1 in the direction of the arrows showing a plurality of joint washers being connected to opposing stiles, opposing panels and a center panel;  
         [0027]    [0027]FIG. 4 is an enlarged sectional view of the reinforced fire retardant panel door of the present invention taken along lines  4 - 4  of FIG. 1 in the direction of the arrows showing the joint plate embedded into the core and held into place by screws for reinforcing a tongue and groove joint between the stile and rail; and  
         [0028]    [0028]FIG. 5 is an enlarged sectional view of the reinforced fire retardant panel door of the present invention of FIG. 3 b  showing intumescent material embedded within the tongue and groove joint.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    The reinforced fire retardant panel door  10  of the preferred embodiment of the present invention is represented in detail by FIGS. 1 through 5 of the patent drawings. The fire retardant panel door  10  is used to fireproof an area and to prevent fire from spreading to other areas within a home dwelling, commercial building or industrial plant.  
         [0030]    Fire retardant panel door  10  includes stiles  12  and  14 , rails  16  and  18 , a center panel  20 , a first panel  30  and a second panel  50 , as shown in FIGS.  1  to  4 . The fire retardant panel door  10  is hingedly connected between a left or right door jamb  22  or  24  and positioned below an upper header  26 , as depicted in FIGS. 2 a  and  3   a . Panel  30  has edges  32 ,  34 ,  36  and  38  and panel  50  has edges  52 ,  54 ,  56  and  58 . Stiles  12  and  14 , rails  16  and  18 , and panels  20 ,  30  and  50  have a core section  40  formed of Tectonite material. Wood applique  42  and molding  44  are applied to the exterior surface of stiles  12  and  14 , rails  16  and  18 , and panels  20 ,  30  and  50 , as shown in FIGS. 1, 2 a ,  2   b ,  3   a  and  3   b  of the drawings.  
         [0031]    Tongue and groove joints  60  and  62  are used to connect panel  30  to the door  10 , and tongue and groove joints  64  and  66  are used to connect panel  30  to the door  10 . Tongue and groove joints  68  and  70  are used to connect panel  50  to the door  10 , and tongue and groove joints  72  and  74  are used to connect panel  50  to the door  10 . To reinforce the tongue and groove joints  60 ,  62 ,  64 ,  66 ,  68 ,  70 ,  72  and  74 , the present invention employs eight (8) steel joint washers  80 ,  82 ,  84 ,  86 ,  88 ,  90 ,  92  and  94  that are 2½ inches in diameter and ⅛ inch thick. As shown in FIGS. 1, 2 a ,  2   b ,  3   a  and  3   b , the eight (8) joint washers reinforce the joints between the panels  30  and  50 , and the stiles  12  and  14 , the rails  16  and  18 , and the center panel  20 . One of the steel joint washers  80  to  94  is placed on each of the four (4) edges  32  to  38  and  52  to  58  of panels  30  and  50 , respectively. Each of the joint washers  80  to  94  is embedded within the core section  40  of the stiles  12 ,  14 , the rails  16 ,  18 , center panel  20  and the panels  30 ,  50 , as shown in FIGS. 2 a ,  2   b ,  3   a  and  3   b . The joint washers  80  to  94  can be made of metal materials, such as steel, stainless steel alloys, tantalum and titanium alloys. Additional washers may be employed for additional strength, if desired.  
         [0032]    To reinforce the connection between the stiles  12  and  14  and the rails  16  and  18 , the present invention employs four (4) joint plates  100 ,  102 ,  104  and  106  that are each 3 inches by 6 inches, and ⅛ inch thick. Preferably, they are rectangular in shape and each have two (2) screw hole openings  110  and  112  for receiving screws  114  and  116  to hold the joint plates  100  to  106  in place, as shown in FIGS. 1, 2 and  4  of the patent drawings. Each of the joint plates are embedded within the core section  40  of the stiles  12 ,  14  and the rails  16 ,  18 , as shown in FIGS. 2 a  and  4  of the drawings. The joint plates  100  to  106  can be made of metal materials, such as steel, stainless steel alloys, tantalum and titanium alloys.  
         [0033]    To further reinforce door  10 , intumescent material  120  is embedded in each of the tongue and groove joints  60  to  74 , and is also applied to outer perimeter edges  12   a ,  14   a ,  16   a ,  18   a  of the stiles  12 ,  14  and the rails  16 ,  18 , respectively, as shown in FIGS.  1  to  4  of the drawings. The intumescent material  120  expands in the presence of excessive heat and/or fire such that the intumescent material  120  closes and seals each of the tongue and groove points  60  to  74  to prevent the spread of the excessive heat and/or fire through the fire retardant panel door  10 . Additionally, the intumescent material  120  on the outer perimeter edges  12   a ,  14   a ,  16   a  and  18   a  of the stiles and rails  12 ,  14 ,  16  and  18 , respectively, also expands in the presence of excessive heat and/or fire such that the intumescent material  120  closes and seals the perimeter of the fire retardant panel door  10  within the jambs  22 ,  24  and header  26  of the door frame (not shown) to also prevent the spread of the excessive heat and/or fire through the fire retardant panel door  10  and door frame.  
         [0034]    The core section  40  is made from Tectonite™ material which is manufactured by and is available from Warm Springs Composite Products Company of Warm Springs, Oreg. of the United States. The core section  40  is a fire resistant, insulative composite blocking material suitable for use in door  10  of the present invention. The Tectonite™ material has a fire rating above 90 minutes and is used for the core section  40  as a single component construction. The core section (blocking material)  40 , the joint washers  80  to  94 , and the joint plates  102  to  106  all provide structural support, strength and stiffness to the door  10  construction. It is understood that the core (blocking material) section  40  can be made of any fire resistant blocking material approved for fire door applications which has a proven fire door rating.  
         [0035]    In operation, when fire or excessive heat occurs, the intumescent material  120  expands and provides closing and sealing of all the tongue and groove joints  60  to  74  and also provides closing and sealing of the perimeter of the fire retardant panel door  10  within its door frame (not shown), thus preventing the spread of the fire through the fire retardant panel door. Further, the core section  40 , the steel joint washers  80  to  94 , and the steel joint plates  100  to  106  in combination with each other, all cooperate to provide additional structural support, strength and stiffness to the door  10  construction, thus preventing the door  10  from buckling in the presence of excessive heat and/or fire.  
       ADVANTAGES OF THE PRESENT INVENTION  
       [0036]    Accordingly, it is an advantage of the present invention that it provides for a reinforced fire retardant panel door that prevents buckling of the door during a fire.  
         [0037]    Another advantage of the present invention is that it provides for a reinforced fire retardant panel door that has additional structural support, strength and stiffness with the use of a plurality of joint steel washers and a plurality of joint steel plates which are embedded within the fire resistant blocking material (core section) of the door for preventing the buckling of the fire door during a fire.  
         [0038]    Another advantage of the present invention is that it provides for a reinforced fire retardant panel door that has supplemental fire resistant materials strategically embedded and placed within the tongue and groove joints of the fire resistant panel door, as well as supplemental fire resistant materials placed on the perimeter edges of the fire resistant panel door for preventing the spread of fire through the door and door frame.  
         [0039]    Another advantage of the present invention is that it provides for a reinforced fire retardant panel door that has fire resistant materials being intumescent material that expands in the presence of fire such that the intumescent material closes and seals the component tongue and groove joints, as well as the perimeter edges of the fire retardant panel door for preventing the spread of fire through the door and door frame.  
         [0040]    Another advantage of the present invention is that it provides for a reinforced fire retardant panel door that is used as part of an interior or exterior personal living space, or workspace being installed within home dwellings, commercial buildings or industrial plants.  
         [0041]    Another advantage of the present invention is that it provides for a reinforced fire retardant panel door that is aesthetically pleasing having the appearance of natural wood, and has achieved a successful fire rating of at least 90 minutes and passes a positive pressure test, and is easily installed in a building.  
         [0042]    A further advantage of the present invention is that it provides for a reinforced fire retardant panel door that can be mass produced in an automated and economical matter and is readily affordable to the builder or consumer.  
         [0043]    A latitude of modification, change, and substitution is intended in the foregoing disclosure, and in some instances, some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

Summary:
A reinforced fire retardant panel door that prevents buckling of the door during a fire. The reinforced fire retardant panel door includes a door member having at least one door panel and stiles and rails. The reinforced fire retardant panel door also includes at least four (4) steel washer inserts embedded within the door member for connecting at least one door panel to the stiles and rails. Further, the reinforced fire retardant panel door includes at least four (4) steel joint plates embedded within the door member for connecting said stiles and rails together more securely for providing increased structural strength and stiffness to the door in order to prevent buckling of the fire retardant panel door during a fire.