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CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from U.S. patent application Ser. No. 10/863,696 filed on Jun. 8, 2004, which claims priority from U.S. Provisional Patent Application Ser. No. 60/563,638, for an Improved Hardwood Flooring Board filed on Apr. 20, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     In a large number of commercial and residential buildings, hardwood flooring surfaces are utilized to provide an aesthetically pleasing appearance to the interior of the building. In most instances, the flooring surface is formed from a number of flooring boards or planks engaged with one another to form the flooring surface. These boards are usually formed entirely of the desired hardwood, with each board being formed into the desired shape to facilitate the use of the boards to form the flooring surface.  
         [0003]     However, while these hardwood flooring surfaces provide the desired appearance to the interior of the building, the natural characteristics of traditional solid wood flooring often create challenges during installation and can develop later effecting the long term performance of the floor.  
         [0004]     To reduce these problems, a number of different types of flooring boards has been developed that are formed from non-hardwood materials that give the appearance of a hardwood. While these boards are faster to install and can be less expensive, the quality of the hardwood appearance is often unsatisfactory, and long term performance is poor, as normal wear and tear can often damage the hardwood-appearing surface of the boards, exposing the non-hardwood material forming the board.  
         [0005]     Therefore, it is desirable to develop a flooring board that is made of wood, yet is easy to install with a special profile and construction that insures long term performance. Further, the board should be able to be maintained in a manner similar to that of a hardwood surface and offer all the aesthetic features of a traditional solid wood floor.  
       SUMMARY OF THE INVENTION  
       [0006]     According to a primary aspect of the present invention, an improved hardwood flooring is constructed with upper and lower layers formed of a conventional flooring material and a central or middle layer formed of an alternative non-hardwood flooring material. The board includes a hardwood layer forming the upper layer of the board to give the board the appearance of a conventional hardwood flooring surface when the boards are assembled to form the flooring surface. This enables the boards to be sanded when damaged similarly to a hardwood only board in order to maintain the hardwood appearance of the board.  
         [0007]     However, the use of the alternative flooring material as the middle layer or core of the board greatly increases the dimensional stability of the board. In addition, the raw material cost for the non-hardwood material forming the middle layer costs less than that of the hardwood forming the upper layer. Further, the types of non-hardwood materials that can be used to form the middle layer can be chosen to enhance various properties of the board, such as the dimensional stability, longer average board length and a specially milled connection between each board that significantly minimizes any future visible contraction of each board.  
         [0008]     Other aspects, features and advantages of the present invention will be made apparent from the following detailed description taken together with the drawing and figure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The drawings illustrate the best most currently contemplated of practicing the present invention.  
         [0010]     In the drawings:  
         [0011]      FIG. 1  is an isometric view of a flooring surface constructed using boards formed according to the present invention;  
         [0012]      FIG. 2  is an isometric view of a flooring board constructed according to the present invention;  
         [0013]      FIG. 3  is a cross-sectional view along line  3 - 3  of  FIG. 2 ;  
         [0014]      FIGS. 4A-4B  are partially broken away cross-sectional views of the boards of  FIG. 3  in connected and disconnected configurations; and  
         [0015]      FIGS. 5A-5D  are partially broken away cross-sectional views illustrating the connection of the boards of  FIGS. 4A-4B . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     With reference now to the drawing figures in which like reference numerals designate like parts throughout the disclosure, a flooring surface is shown generally at  8  in  FIG. 1 . The surface is formed over a support surface  9 , such as a concrete slab, from a number of flooring boards  10  constructed according the present invention.  
         [0017]     Looking now at  FIGS. 2-3 , each board  10  is between 0.10 inches and 1.00 inches, and preferably about 0.75 inches in thickness, and includes an upper layer  12 , a core or middle layer  14  and a lower layer  16 . The upper layer  12  and the lower layer  16  can be attached to opposites sides of the middle layer  14  in any conventional manner, such as by using an adhesive or mechanical fasteners, in conjunction with heat and/or pressure, so as long as the upper layer  12  and bottom layer  16  are prevented from delaminating or otherwise becoming detached from the middle layer  14  during the installation and use of the boards  10 .  
         [0018]     The upper layer  12  is formed of a conventional hardwood material in order to provide the desired aesthetic appearance to the flooring surface  8  constructed using the boards  10 . Any particular hardwood material can be used for upper layer  12 , depending upon the desired appearance for the flooring surface  8 . The upper layer  12  has a thickness of between about three (3) mm and about five (5) mm. This allows the upper layer  12  to be sanded approximately 3-5 times before the layer  12  is worn completely through. Thus, any gouging, scratching or refinishing of the upper layer  12  can be done similarly to a conventional hardwood flooring board without exposing the middle layer  14 , as occurs with the prior art engineered non-hardwood flooring boards. Also, due to the use of a hardwood material to form the upper layer  12 , the board  10  can have a face grade from the National Oak Flooring Manufacturers Association similar to the boards formed entirely of the hardwood.  
         [0019]     The lower layer  16  can also be formed from a hardwood material similar to the upper layer  12 , or can be formed from a non-hardwood material that has certain selected properties, e.g., water resistance or rigidity, as a base for the board  10 . The material forming the lower layer  16  is capable of being secured to the support surface  9  by any suitable means, such as an adhesive, when the boards  10  are attached “in flex,” or a mechanical fastener, e.g., a nail or screw, to hold the boards  10  thereon to form the flooring surface  8 . The lower layer  16  also has a thickness comparable to the upper layer  12 , preferably between about three (3) mm and about five (5) mm.  
         [0020]     The central layer  14  is formed of an alternative, non-hardwood flooring material that provides a stable core for the board  10 . The non-hardwood material used in the middle layer  14  can be any suitable generally rigid and non-compressible material, but is preferably a material such as High Density Fiber Board, Medium Density Fiber Board, plywood, chipboard, Orientated Strand Board, a cheaper wood or wood composite material, or the like, in comparison to the materials utilized to form the upper layer  12  and the bottom layer  16 . This non-hardwood material can be selected and used to form the middle layer  14  to create boards  10  that are more dimensionally stable such as by orienting the non-hardwood material in a direction perpendicular to the length of the board  10  and the grain of the hardwood forming the upper layer  12 . This enables the boards  10  to be made longer and wider than conventional flooring boards which results in fewer boards  10  being required to form the flooring surface  8 . Also, the non-hardwood material forming the middle layer  14  can be formed or milled very precisely prior to assembly into the board  10 , which results in boards  10  with tight tolerances than can easily by engaged with one another to form the flooring surface  8 .  
         [0021]     To accomplish this, the middle layer  14  is preferably formed to have a thickness of between about six (6) mm and fifteen (15) mm. Thus, the middle layer  14  forms between about 40% and about 75% of the total material of the board  10 , more preferably between 45% and 65% of the total board material, and most preferably about 55% of the total board material.  
         [0022]     In order to enable the boards  10  to be secured to one another to form the flooring surface  8 , the central layer  14  also includes a tongue  18  and a groove  20  positioned on and extending along opposite sides of the board  10 . The tongue  18  is preferably formed integrally with the middle layer  14 , but may be formed of a separate, more rigid or more flexible material that is secured to the board  10 , if desired. The tongue  18  can have any suitable shape but preferably has a base portion  21  extending outwardly from the middle layer  14  that has a rounded end  22  disposed opposite the middle layer  14 . A notch or recess  24  is formed on one side of the base portion  21  adjacent the upper layer  12  to facilitate the engagement of the tongue  18  within the groove  20  and to allow a certain amount of expansion of the tongue  18  due to the changing moisture content of the board  10 .  
         [0023]     The groove  20  is shaped to be complimentary to the tongue  18  and preferably defines an interior space  28  slightly greater than the size of the tongue  18  to accommodate the normal expansion and contraction of the tongue  18  based on the changing moisture content of the board  10 . The tongue  18  can be secured within the groove  20  simply by using a friction fit between them, or an adhesive (not shown) or other suitable means to permanently hold the tongue  18  in engagement with the groove  20 . The groove  20  can be milled out of the middle layer  14  during the formation of the middle layer  14 , similarly to the tongue  18 .  
         [0024]     The side of the board  10  including either the tongue  18  or the groove  20  can be formed such that the upper layer  12  extends outwardly further than the lower layer  14  to enable the boards  10  to be joined to form a surface  8  with a minimum of space between the upper layers  12  on adjacent boards  10 .  
         [0025]     In one particularly preferred embodiment shown best in FIGS.  3 ,  4 A- 4 B and  5 A- 5 D, the groove  20  includes one of a connecting rib  26  or connecting notch  28  integrally formed therein. The rib  26  or notch  28  is engageable with an opposed rib  26  or notch  28  formed on the tongue  18 . The engagement of the rib  26  with the notch  28  secures the tongue  18  in engagement with the groove  20  without using any materials other than the boards  10  themselves, thus reducing the complexity of forming the surface  8  using the boards  10 . To properly engage the notch  28  with the rib  26 , the tongue  18  is formed with a recessed portion  30  that enables the tongue  18  and notch  28  to be inserted beneath the rib  26  and then engaged with one another to secure the boards  10  to each other as illustrated in  FIGS. 5A-5D . The engagement of the rib  26  with the notch  28  maintains the positioning of the adjacent boards  10  with one another, such that the boards  10  present a continuous flooring surface  8  as the individual boards  10  take on and lose moisture due to the changing environmental conditions.  
         [0026]     Also, in order to enable the boards  10  to be more easily attached to the support surface, the lower layer  16  may include one or more recesses  32  within which an adhesive or other fastening means to be utilized can be positioned to enable the board  10  to be positioned flush on the support surface  9  when secured to the support surface  9 . In situations where mechanical fasteners (not shown) such as nails or screws are used, the fastener on occasion creates splinters when breaking through the bottom layer  16 , the recesses  32  is designated to facilitate these splinters. More particularly, the recesses  32  enable the board  10 , and specifically the lower layer  16 , to flex under the force of the fastener being engaged with the board  10  and the support surface  9 .  
         [0027]     Various alternatives are contemplated as being within the scope of the following claims, particularly pointing out and distinctly claiming a subject matter regarded as a the invention.  
         [0028]     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

Summary:
The present invention is a hardwood flooring board including a middle layer formed from a non-hardwood flooring material and a hardwood material upper layer which is secured to an upper surface of the middle layer. The middle layer forms between 45% and 75% of the overall material of the board and enables the board to be manufactured to be more dimensionally stable, i.e., wider and longer, than conventional hardwood flooring boards. Also the use of the non-hardwood material in the middle layer greatly increases the dimensional stability and long term performance of the flooring boards, while providing a genuine hardwood appearance to the floor. The board also includes a lower layer that can be formed from either a hardwood material or a non-hardwood material to function as a base for the board.