An improved corner assembly for use with metal framed, floating panel glass doors, windows or wall partitions is provided. The design provides improved structural integrity of frame corner joints such that rail twist and frame racking are minimized. The design features a corner assembly composed of extruded horizontal and vertical framing members where the horizontal framing member is equipped with an integral tongue. The tongue engages a mating groove in the vertical framing member. The sheer block is attached to the horizontal and vertical framing members via mechanical fasteners. Welds are provided at the intersection of the tongue and groove, and between the sheer block and horizontal framing member to provide for increased structural integrity.

CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. provisional patent application No. 61/897,752 filed on Oct. 30, 2013, the entirety of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to metal framed glass panels and more specifically, to an improved corner assembly for metal framed glass doors, windows and wall partitions. 
         [0004]    2. Background of the Invention 
         [0005]    It is quite popular to use metal framed glass panels for doors, windows and wall partitions, particularly in commercial establishments. In such installations, the vertical and horizontal metal rails form the frame for the glass panel and are generally of small width so that the major portion of the door, window or wall partition is composed of the glass panel. Aluminum extrusions are commonly used as the metal framing members. Because of the relatively narrow width of the metal framing members however, it is difficult to form strong corner joints between the horizontal and vertical members. 
         [0006]    Commercial metal framed glass doors in particular are typically subject to heavy use which causes twisting and racking forces to be applied to the doors. Such forces create substantial stresses at the door corner joints. While many prior art commercial doors have corner joints which can withstand these forces, these joints tend to be bulky and cumbersome, and frequently are still subject to failure from the twisting and racking which result from repeated, long term use. 
         [0007]    There remains a need in the art for an improved corner joint construction for metal door frames enclosing glass panels. Such an improved corner joint should provide for greater structural integrity than is presently available in prior art designs to better withstand the rigors of heavy use. Any such corner joint would be equally applicable to window and wall partition frames which, being stationary, typically are subjected to substantially less stress than metal framed glass doors. 
         [0008]    It is the purpose of the present invention to provide an improved corner assembly for use in constructing metal framed glass panel doors, windows and wall partitions. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides an improved corner assembly for use with metal framed glass doors, windows and wall partitions. The new corner assembly provides for improved structural integrity of the frame corner joints such that rail twist and frame racking are minimized. The new corner assembly features vertical and horizontal framing members interconnected by a sheer block. The horizontal framing members include a tongue extension that interfaces with a groove in the vertical framing members. (This configuration may be reversed.) The tongue and groove construction improves alignment of the framing members and the interconnecting sheer block. A weld formed at the intersection of the tongue and groove improves the structural rigidity of the corner assembly. A combination of mechanical fasteners and welds interconnect the shear block to the vertical and horizontal framing members. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an exploded view of a corner assembly of the present invention showing a vertical framing member, horizontal framing member and sheer block, in accordance with the invention. 
           [0011]      FIG. 2  is a perspective view of the corner assembly of  FIG. 1 , showing, although with different dimensions, a finished corner joint. 
           [0012]      FIG. 3  is a detail of the corner assembly of  FIG. 2 . 
           [0013]      FIG. 4  is an end detail of an end of the horizontal framing member of  FIG. 1 . 
           [0014]      FIG. 5  is a partial top view of the corner assembly of  FIG. 2  showing the a tongue of the horizontal framing member engaged with a mating groove of the vertical framing member. 
           [0015]      FIG. 6  is a detail view of the connection between the tongue of the horizontal framing member and the groove of the vertical framing member of  FIG. 5 . 
           [0016]      FIG. 7  is an end view of the horizontal framing member of  FIG. 2 , showing a door glass installed in the framing member. 
           [0017]      FIG. 8  is a detail view of the corner assembly of  FIG. 1 , shown prior to final finishing operations. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
         [0019]      FIG. 1  shows an exploded view of a preferred embodiment of the door corner assembly  10  of the present invention, and  FIG. 2  shows a finished assembly  10  in accordance with the present invention.  FIGS. 1 and 2  show the preferred corner assembly  10  for only one of the four corners of the door. The assemblies of the three other corners of the door are identical in all material respects. The corner assembly of the present invention  10  is suitable for use with door, window and wall partition framing members of a variety of widths and depths. The present invention corner assembly is not limited to any particular framing member dimensions. 
         [0020]    With reference to  FIGS. 1-6 , the new corner assembly  10  comprises a horizontal framing member  12 , a vertical framing member  14  and a sheer block  16 . The horizontal framing member  12  has ends  18 . The horizontal framing member  12  is hollow with an upper wall  22 , a lower wall  24  and side walls  26 , which define a substantially square or rectangular cross section passageway  28  extending longitudinally between the ends  18 . The upper wall  22  of the horizontal framing member  12  features tongues  30  which extend outwardly from the ends  18 . Extending upwardly from the upper wall  22  of the horizontal framing member  12  are flanged walls  23  which define a center channel  25  therebetween. The center channel  25  extends longitudinally between the ends  18  of the horizontal framing member  12 . The side walls  26  of the horizontal framing member  12  also extend upwardly of the upper wall  22  to form beveled extension walls  27 . The flanged walls  23  and the beveled extension walls  27  define glazing retainer channels  29 . The side walls  26  of the horizontal framing member  12  may extend downwardly below the bottom wall  24  to define an open channel section passageway  54  therebetween. 
         [0021]    The vertical framing member  14  has ends  32 . The vertical framing member  14  is hollow with an inner wall  36 , an outer wall  38  and side walls  40  which define a substantially square or rectangular cross section passageway  42  extending longitudinally between the ends  32 . With particular reference to  FIG. 6 , the inner wall  36  of the vertical framing member  14  features outwardly extending walls  44  with lip flanges  46  which run longitudinally between the ends  32  of the vertical framing member  14  and which define a center groove  48 . The side walls  40  of the vertical framing member  14  also extend outwardly of the inner wall  36  to form beveled extension walls  68 . The outwardly extending walls  44  and the beveled extension walls  68  define outer grooves  70 . 
         [0022]    With reference to  FIGS. 1-7 , the tongue  30  of the upper wall  22  of the horizontal framing member  12  and groove  48  of the inner wall  36  of the vertical framing member  14  are configured such that the tongue  30  is slidably received within the groove  48  when an end  18  of the horizontal framing member  12  abuts the inner wall  36  of the vertical framing member  14  to form an intersection  50  between the horizontal framing member  12  and the vertical framing member  14 . A weld  52  is made at the intersection  50  between the tongue  30  and the groove  48 . 
         [0023]    With particular reference to  FIG. 1 , the shear block  16  of the corner assembly  10  features an H-shaped cross section defined by a mutually opposed inner channel  56  and an outer channel  58 . The inner channel  56  comprises side walls  60  connected to a center wall  64  with the side walls  60  defining the inner channel  56  therebetween. The outer channel comprises side walls  62  connected to the center wall  64  with the side walls  62  defining the outer channel  58  therebetween. In the exemplary embodiment of the shear block  16 , the center wall  64  is common to both the inner and outer channels. The side walls  62  of the outer channel  58  of the h-shaped cross section have end abutment faces  66 . 
         [0024]    The H-shaped cross section of the shear block  16  is configured such that the walls  60  of the inner channel  56  are slidably received within the hollow square or rectangular cross section passageway  28  of the horizontal framing member  12  and the end abutment faces  66  of the outer channel  58  of the sheer block  16  are slidably received within the outer grooves  70  of the vertical framing member  14  and abut the inner wall  36  of the vertical framing member  14 . 
         [0025]    With reference to  FIG. 1 , in the exemplary embodiment, the sheer block is fastened to the vertical framing member  12  by means of a threaded fastener in the form of a bolt  72  and a nut  74 . A threaded end  76  of the bolt  72  passes through a clearance hole  78  formed in the center wall  64  of the H-shaped cross section and a clearance hole  79  in the upper wall  36  of the vertical framing member  14 , (the respective clearance holes  78  and  79  being axially aligned), to engage the nut  74 . The nut  74  is disposed within the hollow square or rectangular cross section passageway  42  of the vertical framing member  14 . In the exemplary embodiment, the nut  74  is a nut-plate configured to be slidably received within the cross section passageway  42  of the vertical framing member  14  and sized to have a width such that the nut  74  will be constrained from rotating by the side walls  40  of the cross section passageway  48  of the vertical framing member  14 . 
         [0026]    With continued reference to  FIGS. 1-4 , in the exemplary embodiment, the sheer block  16  is fastened to the horizontal framing member  12  by screws  80  which pass through clearance holes  84  in upper wall  22  and lower wall  24  of the horizontal framing member  12 . The screws  80  engage with screw engagement portions  82  formed in the sheer block  16 . The screw engagement portions  82  have holes or openings  81  for receipt of the screws  80 . The sheer block  16  may be further secured to the horizontal framing rail  12  via a weld  86  between the sheer block  16  and the upper wall  22  of the horizontal framing rail  12 . Weld penetration between the sheer block  16  and the upper wall  22  of the horizontal framing rail  12  may be enhanced by providing a slot  88  in the horizontal framing rail  12  at the point where the weld  86  is formed. In the exemplary embodiment, the slot  88  and the subsequently formed weld  86  are positioned such that the weld  86  occurs on the center wall  64  of the sheer block  16 . 
         [0027]    Referring to  FIG. 7 , the horizontal framing member  12  is shown with a door glass  90  installed. The door glass  90  rests upon a setting block  96  which is slidably received within the center channel  25 . Fitted within the glazing retainer channels  29  on each side of the door glass  90  are snap-in glazing strips  92  which serve to seal the door glass  90  from the elements. 
         [0028]    The horizontal framing rail  12 , vertical framing rail  14 , and sheer block  16  are preferably aluminum extrusions as aluminum is of relatively light weight with high strength and several alloys that are both weldable and readily produced in extruded form are commercially available. Metallic materials other than aluminum may be used to form the horizontal and vertical framing rails and shear block. Likewise several types of plastic materials are readily extrudable and have sufficient strength to serve in the application. 
         [0029]    With reference to  FIGS. 1-7 , the corner assembly  10  of the present invention is assembled as follows. The shear block  16  is attached to the vertical framing member  14  by means of the clamp bolt  72  which passes through the clearance hole  78  in the center wall  64  of the shear block  16  and through a clearance hole  79  in the upper wall  36  of the vertical framing member  14 . The clamp bolt  72  engages the nut plate  74  which is vertically positioned within the vertical framing member  14 . The clamp bolt  20  is tightened sufficiently to secure the shear block  16  against the inner wall  36  of the vertical framing member  14  by means of clamping force. 
         [0030]    Thereafter, the horizontal framing member  12  is secured to the vertical framing member  14  such that the shear block  16  (secured to the vertical framing member via the clamp bolt  72  and nut  74 ) slides within the square or rectangular passageway  28  of the horizontal framing member  12  and the tongue  30  of the horizontal framing member  12  engages, i.e. is slideably received within the groove  48  of the vertical framing member  14 . Thereafter, the horizontal framing member  12  is secured to the shear block  16  by means of fasteners such as screws  80 , which may be self-threading sheet metal screws, which pass through holes  84  in the upper wall  22  and lower wall  24  of the horizontal framing member  12  to engage the screw engagement portions  82  of the shear block  16 . The screws  80  are sufficiently tightened to securely engage the horizontal framing member  12  to the vertical framing member  14 . 
         [0031]    With reference to  FIG. 8 , when the horizontal framing member  12  is positioned flush against the vertical framing member  14 , the clearance holes  84  in the upper and lower walls  22  and  24  of the horizontal framing member  12  are intentionally offset, or misaligned from the holes or openings  81  in screw engagement portions  82  of the sheer block  16 . The intentional misalignment or offset  83  is shown in  FIG. 8 . More specifically, the holes  84  of the horizontal framing member  12  are offset outwardly from the vertical framing member  14 , as shown in  FIG. 8 , so that when the holes  84  are forced into alignment with the openings  81  of the screw engagement portions  82  of the sheer block  16 , and subsequently secured by the screws  80 , compression is induced at the interface between the members  12  and  14 . 
         [0032]    The compression created at the interface between the horizontal and vertical framing members  12  and  14  serves two principle purposes, i.e. the compression creates a more rigid corner joint and it serves to close any gaps that may exist at the interface between the two rails and thus improves the aesthetics of the joint. Experimentation has shown that an offset  83  between the holes  84  of horizontal framing member  12  and the openings  81  in the sheer block  16  within the range of about 0.030 to 0.040 inch to be sufficient to stiffen the corner joint and to close any gaps between the horizontal and vertical framing member  12  and  14 . 
         [0033]    With reference to  FIGS. 2 through 4 , as a final assembly procedure for the corner assembly  10 , the horizontal framing member  12  and the vertical framing member  14  are further secured by means of a weld  52  at the intersection of the horizontal  12  and vertical  14  framing members  50 . In particular, the weld  52  is made at the interface between the tongue  30  of the horizontal framing member  12  and the groove  48  of the vertical framing member  14 . Welding at this intersection provides for greater weld area and better weld penetration between the horizontal  12  and vertical  14  framing members. The horizontal framing member  12  is additionally secured to the shear block  16  by means of a weld  86  which is formed at the slot  88  (see  FIG. 4 ), which is spaced to align with the center wall  64  of the shear block  16 . The slot  88  in the horizontal framing member  12  ensures adequate penetration and fusion of the weld  86  connecting the horizontal framing member  12  to the shear block  16 . 
         [0034]    The corner joint  10  of the present invention lends itself well to production using computer numerical controlled (“CNC”) machining equipment. The use of CNC equipment to finish the extrusions from which the horizontal  12  and vertical  14  framing members, as well as the sheer block  16  are made reduces the errors inherent in non-CNC machining operations and thereby improves the overall quality of the product, as well as the processing efficiency, production scheduling, and cost accountability of the manufacturing process. 
         [0035]    The use of CNC machining equipment is of particular value in forming the tongue  30  of the horizontal framing member  12 . The tongue cannot readily be produced with sufficient precision using hand controlled machining equipment. CNC machining equipment is also of particular value in forming the screw holes  84  of the horizontal framing member  12 . CNC machining allows the holes  84  to placed very accurately relative to an end of the horizontal framing member. Prototype development has shown that similar accuracy cannot readily be obtained with non-CNC equipment. 
         [0036]    The corner assembly of the present invention  10  will typically be used to form door and window frames or wall partitions where a glass pane  90  is desired to be used. In the exemplary embodiment, reference is made to a glass pane. However, the corner assembly  10  of the present invention may be used to frame flat panels comprised of a variety of materials including wood, metallic materials and plastic materials. The panel to be secured is held within the frame constructed using the corner assembly  10  of the present invention using window glazing techniques of which many are known in the art. 
         [0037]    The improved corner joint  10  of the present invention has been described as using a tongue  30  formed on the horizontal framing member  12  to interface with a groove  48  in the vertical framing member  14 . In some glass door, window or wall partition installations however, it may prove impracticable to include the tongue  30  of the present invention in the corner joint assembly. In such installations, glass doors, windows and wall partitions my nevertheless be framed using the same horizontal and vertical framing members  12  and  14  and sheer block  16  and method of assembly of the corner joint assembly  10  of the present invention, with the only modification being the lack of a tongue  30  formed on horizontal framing member  12 . Corner joints  10  constructed without the tongue  30 , while not as strong as corner joints that include the tongue  30 , are nevertheless sufficiently strong for some types of installations. 
         [0038]    As described, a new corner assembly for use in framing glass doors, windows or wall partitions has been presented. Frames constructed using the new corner assembly provide better resistance to rail twist and frame racking. The new corner assembly provides these improvements through the provision of the tongues  30  on each horizontal framing member  12  which mate with the grooves  48  on adjacent vertical framing members. (The tongue and groove arrangement may be reversed, i.e. the tongues may be formed on the vertical framing member to mate with grooves on the horizontal framing member.) The tongues achieve this improvement by improving the alignment between the horizontal  12  and vertical  14  framing members and the shear block  16 , and by improving the strength of the weld at the junction of the framing members. 
         [0039]    The foregoing detailed description and appended drawings are intended as a description of the presently preferred embodiment of the invention and are not intended to represent the only forms in which the present invention may be constructed and/or utilized. Those skilled in the art will understand that modifications and alternative embodiments of the present invention which do not depart from the spirit and scope of the foregoing specification and drawings, and of the claims appended below are possible and practical. It is intended that the claims cover all such modifications and alternative embodiments.