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FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to the field of flooring including wood laminate flooring, such as high density fiberboard (HDF) laminate flooring and medium density fiberboard (MDF) laminate flooring, solid wood flooring and engineered wood flooring, which includes a plurality of wood layers. More particularly, the present invention relates flooring having locking edge profiles  
       BACKGROUND OF THE INVENTION  
       [0002]     Floor covering panels, including wood laminate flooring, solid wood flooring and engineered wood flooring are well known in the prior art. To increase the ease of installation by removing the need for glues or adhesives, these floor coverings have been made with locking edges having a tongue with a projection and a groove with a corresponding depression in the core of the floor covering panel that together form coupling parts or means, which prevents substantial movement perpendicular to the major surfaces of the laminate flooring and perpendicular to the locking edges. In some embodiments the projection may be in the groove and the corresponding depression in the tongue.  
         [0003]     Earlier locking laminates had locking edges on all four sides of the laminate. While installation of these laminates was easier than prior laminates that required the edges to be glued, installation was somewhat cumbersome since previously laid laminate panels had to be angled away from the subfloor on which the laminate was laid to permit and an additional panel to lock into place.  
         [0004]     To overcome this problem, a lock and fold or lock and drop laminate was developed in which two of the opposite long edges had the standard locking profile in the core and the other two short opposite edges had a profile in the core, such as shown in  FIG. 1 . These lock and fold panels were installed by angling a long locking edge into a previously installed row of panels and dropping or locking the projection of the tongue of the short side into the depression of the lower lip forming the groove in the short side.  
         [0005]     This worked well for laminate panels of about 3½ inches in width. However, due to the surfaces of the short lock and fold edges which engage each other being vertical, the flooring elements not being substantially urged together, the dimensions of panels, particularly the thickness of the panel, the depth of the depression and the height of the projection, and the cushion effect of the underlayment between the laminate and the substrate, the joints at the short lock and drop edges of wider panels, such as 5 inch wide and greater widths, tend to disengage when the laminate was stepped upon near the short edge. This causes ridges to form in the upper horizontal surface between the laminate panels resulting in an uneven walking surface.  
         [0006]     Palsson et al. U.S. Pat. No. 7,121,058 discloses a flooring material with conventional locking profiles on two opposite edges. The other two opposite edges are a male vertical assembly joining member and a female vertical assembly joining member which mate by only vertical motion. The male vertical assembly joining member includes an inclined lower cheek surface and at least one snapping hook. The female vertical assembly joining member includes an inclined upper cheek surface and at least one under cut.  
         [0007]     On assembly, the snapping hook and under cut interact to prevent the floor elements from disengaging vertically. The lower and upper inclined cheek surfaces engage to prevent the elements from disengaging horizontally. The inclined cheek surfaces also urge the floor elements together, which prohibit disengagement of the snapping hook and under cut without substantial damage to the snapping hook and/or under cut.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention overcomes this problem by controlling the friction between the short edges of adjacent installed laminate panels. The friction is small enough to permit easy installation, i.e. requiring a minimum of pressure near the short edge during installation to engage the coupling parts, while being sufficiently great to deter disengagement during normal use when the installed panel is step on near the short end. However, the structure of the present lock and fold edge permits the laminate panels to be disengaged and reassembled, at least a number of times, without permanent damage to the lock and fold edges resulting in the loss of the desired friction.  
         [0009]     Various embodiments are shown in the enclosed drawings. These include a small projection and groove feature on one or two vertical surfaces (perpendicular to the major, or upper and lower, surfaces of the laminate panel) of the second opposed side edges that are folded into engagement. The profile of the small projection and groove can be rectangular or rounded or an elongated projection. The projection can be formed as one panel from the coupling projection or groove, or be adhered to the vertical surface of the second opposed side edges.  
         [0010]     In another embodiment, the projection can have a flat surface parallel to the upper surface of the laminate on the side of the projection toward the upper decorative surface and a curved surface opposite the flat surface. The curved surface reduces the pressure necessary to engage the short ends of the laminate panels and the flat surface, which engages a corresponding flat surface in the surface of the corresponding second side edge, increases the pressure necessary to disengage the panels.  
         [0011]     Rather that a small projection and groove, the vertical or perpendicular surfaces of the second opposed side edges can be roughened, such as by a saw tooth profile or the application of a particulate containing composition. In another embodiment, a pressure sensitive adhesive can be applied to one or both of the adjacent perpendicular surfaces of the second opposed side edges.  
         [0012]     The disengaging pressure can also be increased by modifying the horizontal surfaces (surfaces parallel to the upper surface of the laminate). A hook material can be adhered to one horizontal surface on one of the second opposed side edges and a loop material adhered to the corresponding adjacent side edge.  
         [0013]     In another embodiment, the hook and loop material can be replaced with a pressure sensitive adhesive on one or both of the surfaces parallel to the upper surface of the laminate panel. In still another embodiment, one parallel surface may have a wedge projecting from the surface with the distal portion of the wedge having a greater cross-section than the portion adjacent the surface, and the adjacent parallel surface may have a correspondingly shaped groove. In yet another embodiment, the projection from the parallel surface can be in the shape of an arrowhead and the corresponding groove may have a simple rectangular cross-section.  
         [0014]     In one embodiment, one or more of the surfaces perpendicular to the upper surface of the laminate panel may have an “S-shaped” or double-curved profile. If the double-curved profile intersects the upper or lower surfaces of the laminate, it may be beveled to deter damages as the panels are engaged.  
         [0015]     Other profiles are also shown. The key features in some embodiments are that at least one pair of the corresponding surfaces of second two opposed edges are perpendicular to the upper surface and the corresponding perpendicular surfaces are non-planar, whereby one of the corresponding surfaces engages the other corresponding surface and the pressure to engage and disengage the laminate panel is increased slightly. In other embodiments corresponding surfaces parallel to the upper decorative surface have features that increase the force to disengage the panels. One of ordinary skill in the art can determine, without undue experimentation, the dimensions and tolerances necessary to permit easy installation, while deterring disengagement during normal use. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a cross-section showing the long and short edges of a prior art lock and fold profile.  
         [0017]      FIG. 2  is a cross-section showing short folding edge of another prior art lock and fold profile.  
         [0018]      FIG. 3  is a cross-section showing short folding edge of still another prior art lock and fold profile.  
         [0019]      FIG. 4  is a cross-section showing a first embodiment of the present folding edge.  
         [0020]      FIG. 5  is a cross-section showing a second embodiment of the present folding edge.  
         [0021]      FIG. 6  is a cross-section showing a third embodiment of the present folding edge.  
         [0022]      FIG. 7  is a cross-section showing a fourth embodiment of the present folding edge.  
         [0023]      FIG. 8  is a cross-section showing a fifth embodiment of the present folding edge.  
         [0024]      FIG. 9  is a cross-section showing a sixth embodiment of the present folding edge.  
         [0025]      FIG. 10  is a cross-section showing a seventh embodiment of the present folding edge.  
         [0026]      FIG. 11  is a cross-section showing an eighth embodiment of the present folding edge.  
         [0027]      FIG. 12  is a cross-section showing a ninth embodiment of the present folding edge.  
         [0028]      FIG. 13  is a cross-section showing a tenth embodiment of the present folding edge.  
         [0029]      FIG. 14  is a cross-section showing an eleventh embodiment of the present folding edge.  
         [0030]      FIG. 15  is a cross-section showing a twelfth embodiment of the present folding edge.  
         [0031]      FIG. 16  is a cross-section showing a thirteenth embodiment of the present folding edge.  
         [0032]      FIG. 17  is a cross-section showing a fourteenth embodiment of the present folding edge.  
         [0033]      FIG. 18  is a cross-section showing a fifteenth embodiment of the present folding edge.  
         [0034]      FIG. 19  is a cross-section showing a sixteenth embodiment of the present folding edge.  
         [0035]      FIG. 20  is a cross-section showing a seventeenth embodiment of the present folding edge.  
         [0036]      FIG. 21  is a cross-section showing an eighteenth embodiment of the present folding edge. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]      FIG. 1  shows the lock and fold profile of the prior art. The opposite long edges had the standard locking profile as shown on panels  1  and  2  in  FIG. 1 . The other two short opposite edges are shown on panels  3  and  4  in  FIG. 1 . These lock and fold panels were installed by angling a long locking edge of panel  2  into a previously installed row of panels such as panel  1 . Panel  2  is then rotated about the contact point  5  between panels  1  and  2 , thereby dropping or locking the locking projection  6  of short side into the locking groove  7  in the other short side.  
         [0038]     The upper lip locking projection  6  is formed on the upper lip  8  of the short side of panel  4  between the distal end  9  and the upper lip proximal groove  10 . The upper lip proximal groove  10  is formed between the upper lip locking projection  6  and the body of the panel  4  adjacent the lower surface  11 . The upper lip  8  includes an upper lip distal contact surface  12  and an upper lip proximal contact surface  14 . The upper lip distal contact surface  12  is adjacent the upper decorative surface  13 . The upper lip proximal contact surface  14  is between the lower surface  15  of the upper lip locking projection  6  and the upper surface  10 ″ of the upper lip proximal groove  10 . The upper lip contact surfaces  12  and  14  are substantially perpendicular to the upper decorative surface  13 .  
         [0039]     The lower lip locking groove  7  is formed on the lower lip  16  of the short side of panel  3  between the lower lip distal projection  17  and the body of the panel  3  adjacent the upper decorative surface  13 . The lower lip  16  includes a lower lip proximal contact surface  18  and a lower lip distal contact surface  19 . The lower lip proximal contact surface  18  is adjacent the upper decorative surface  13 . The lower lip distal contact surface  19  is between the lower surface  20  of the lower lip locking groove  7  and the upper surface  21  of the lower lip distal projection  17 . The lower lip contact surfaces  18  and  19  are substantially perpendicular to the upper decorative surface  13 .  
         [0040]     The fold joint on the short side of panels  3  and  4  can be freely engaged, disengaged and reengaged. However, if the panels  3  and  4  are greater then 3.5 inches in width, they tend to disengage when the laminate was stepped upon near the short edge, particularly if the panels are laminate panels. This causes ridges to form in the upper horizontal surface between the laminate panels resulting in an uneven walking surface.  
         [0041]      FIGS. 2 and 3  show other prior art short side fold joints of a lock and fold panel. The long side joints can be similar to the long side joint of panels  1  and  2  of  FIG. 1 . The short side joints in  FIGS. 2 and 3  are similar to the short side joint of panels  3  and  4  of  FIG. 1  except the upper lip proximal contact surface  10 ′ and lower lip distal contact surface  19 ′ are slanted, that is not substantially perpendicular to the upper surface  13 ; the upper lip distal contact surface  12 ′ includes a snapping hook  22 ; and the lower lip proximal contact surface  18 ′ includes an under cut  23 .  
         [0042]     The slanted contact surfaces  10 ′ and  19 ′ urge the panels  3 ′ and  4 ′ together. This ensures locking of the snapping hook  22  and under cut  23 , but makes disengagement of the short side fold joint prohibitive without damaging the snapping hook  22  and/or under cut  23 . Therefore, if the panels  3 ′ and  4 ′ are disengaged, they cannot be reengaged without loss of the desired force which deters ridges forming in the upper horizontal surface between the panels when one panel is stepped on near the fold joint. Therefore, if the panels are disengaged and reengaged an uneven walking surface results.  
         [0043]     This problem is overcome in the present invention by keeping the contact surfaces substantially perpendicular to the upper decorative surface, while increasing and controlling the friction between the contact surfaces as the panels are engaged, disengaged and reengaged. The increased friction results from a number of different force increasing means shown in FIGS.  4  to  20 .  
         [0044]     In  FIG. 4 , the upper lip distal contact surface  12  includes a small projection  24  and the lower lip proximal contact surface  18  includes a corresponding small groove  25 . When the short side fold joint is engaged, the small projection  24  lies within the small groove  25 , providing increased friction or force if the panels are urged to disengage.  
         [0045]     The embodiment shown in  FIG. 5  includes a small projection  24 ′ in the upper lip proximal contact surface  10  and a corresponding small groove  25 ′ in the lower lip distal contact surface  19 . When the short side fold joint is engaged, the small projection  24 ′ lies within the small groove  25 ′, providing increased friction or force if the panels are urged to disengage.  
         [0046]     The locations of the small projections and small grooves in  FIGS. 4 and 5  can be reversed, as shown in  FIG. 6 . Also, small projections and corresponding small grooves can be included in all four contact surfaces, as shown in Figure where the upper lip distal contact surface  12  includes a small groove  27 , the lower lip proximal contact surface  18  includes a corresponding small projection  28 , the upper lip proximal contact surface  10  includes a small groove  29  and the lower lip distal contact surface  19  includes a corresponding small projection  30 . Each small projection may have a corresponding groove or the grooves may be omitted.  
         [0047]      FIG. 7  show an embodiment where a loop material  31  is adhered to the locking projection  15  on the upper lip and a hook material  32  is adhered to the locking groove  20  on the lower lip. Again, the locations of the loop material and hook material can be reversed. It may be possible to adhere the hook material and loop material to the upper lip distal contact surface and the lower lip proximal contact surface or to the upper lip proximal contact surface and the lower lip distal contact surface.  
         [0048]     As shown in  FIGS. 8 and 9 , pressure sensitive adhesive can provide the increased friction or force. Pressure sensitive adhesive  34  can be adhered to the lower lip proximal contact surface  18  and pressure sensitive adhesive  33  can be adhered to the upper lip distal contact surface  12 , as in  FIG. 8 .  
         [0049]     In  FIG. 9 , pressure sensitive adhesive  35  can be adhered to the locking groove  20  and pressure sensitive adhesive  36  can be adhered to the locking projection  15 . As with the hook material and loop material, pressure sensitive adhesive can be adhered to the upper lip proximal contact surface and the lower lip distal contact surface. The pressure sensitive adhesive can be adhered to all four contact surfaces; to two of the corresponding contact surfaces, the locking projection and the locking groove; or to all three corresponding surfaces.  
         [0050]      FIG. 10  shows an embodiment where the lower lip proximal contact surface  18  and the upper lip distal contact surface  12  are roughened at  37  and  38 , respectively. The upper lip proximal contact surface  10  and the lower lip distal contact surface  19  could be roughened in a similar manner as shown at  39  and  40 , respectively, as shown in  FIG. 11 . In another embodiment, all four the contact surfaces could be roughened.  
         [0051]      FIGS. 12 and 13  are similar to  FIGS. 4 and 5 , except the projections  24 ″ and  25 ″ in  FIGS. 12 and 13  are adhered to the upper lip distal contact surface  12  and lower lip distal contact surface  19  rather than being integral with the upper lip and lower lip. The projections can be made from a resilient material, such as rubber or thermoplastic. Of course, similar the integral projections, the adhered projections can be adhered to lower lip proximal contact surface, the upper lip proximal contact surface, or two of the non-corresponding contact surfaces. Each adhered projection may have a corresponding groove or the grooves may be omitted.  
         [0052]      FIG. 14  shows a projection  41  and groove  42  which are generally rectangular in cross-section. Such a projection can be substituted for the small projections discussed with regard to the  FIGS. 4 and 5  embodiments.  
         [0053]     The embodiment shown in  FIG. 15  includes an upper lip distal contact surface  12 ′ and a lower lip proximal contact surface  18 ′ which have a double curved profile. Such a profile can also be used on the lower lip distal contact surface and an upper lip proximal contact surface, or on all four contact surfaces.  
         [0054]      FIG. 16  shows an embodiment where the locking groove  20  has a wedge  43  projecting from the surface with the distal portion of the wedge having a greater cross-section than the proximal portion of the wedge. The locking projection  15  has a correspondingly shaped groove  44 . The wedge could also be located in the locking projection and the correspondingly shaped groove could be located in the locking groove.  
         [0055]     The embodiment shown in  FIG. 17  is similar to the embodiment of  FIG. 16  except the projection  45  is shaped like and arrow and the groove  46  has a simple rectangular cross-section. The width of the arrowhead must be greater than the width of the groove. Again, the locations of the arrowhead projection and groove can be reversed.  
         [0056]     In the embodiments in which the force increasing means is located on the upper surface of the locking groove and the lower surface of the locking projection ( FIGS. 7, 9 ,  16  and  17 ), the lower lip distal projection and the upper lip proximal groove are not required. The force increasing means in these embodiments not only deter separation in a direction perpendicular to the upper decorative surface, but also deter separation in a direction parallel to the upper decorative surface. These embodiments are shown in FIGS.  18  to  21 , where the force increasing means include loop material  31  and a hook material  32  ( FIG. 18 ), pressure sensitive adhesive  35  and  36  ( FIG. 19 ), wedge  43  and correspondingly shaped groove  44  ( FIG. 20 ), and arrowhead projection  45  and groove  46  ( FIG. 21 ).

Summary:
Lock and fold floor covering panels can be installed by angling a long locking edge into a previously installed row of panels and dropping or locking the projection of the tongue of the short side into the depression of the lower lip forming the groove in the short side. By incorporating a force increasing means in the fold joint, the width of the panels that can be installed with a lock and fold system can be increased beyond the conventionally accepted 3.5 inches. The fold joint is designed to permit it to be engaged, disengaged and reengaged without damaging the fold joint.