Patent Publication Number: US-6212836-B1

Title: Self-aligning drywall corner bead

Description:
FIELD OF THE INVENTION 
     The present invention relates to corner beads for drywall corner installation and more specifically to such a product that is self-aligning in installation. 
     BACKGROUND OF THE INVENTION 
     Typically, a corner bead for trimming a drywall corner has a central portion with two lateral edges and two flange portions, each extending from one of the lateral edges of the central portion. 
     It is also known to provide the flange portions with an array of apertures, either circular apertures or elongated slots, whereby the “mud”, when pressed onto the outer surface of the flange portions, can be thus pressed through the apertures or holes and into intimate contact with the underlying drywall. When pressed through the apertures such material or “mud” bonds with and helps to attach the corner bead to the underlying drywall. 
     Commonly, the central portion has an arcuate profile and defines a convex surface and a concave surface, whereupon the convex surface becomes the outer surface in use. If the convex surface has a large radius, for example within the range of from about 0.375 to about 1.5 inches, it is commonly known as a “bullnose” corner bead. 
     Weldy, U.S. Pat. No. Re. 34,547 discloses various corner beads, two-way and three-way corners having central portions with an arcuate profile and having two flange portions. 
     Koenig et al, U.S. Pat. No. 5,752,353 describes a drywall trimming article having an arcuately profiled, elongated central portion and two flange portions that are extruded unitarily. Each flange has a series or array of apertures as described above. In the case of Koenig et al, the outer surface of the corner bead is coated with a fibrous material to promote adhesion of the subsequently applied “mud”. 
     In installation, the corner bead is typically stapled or glued to the drywall corner prior to application of the dry wall finishing material or “mud” to maintain the positioning of the corner bead during “mud” application. The gluing or stapling can be a time consuming process in an otherwise rapid application process Additionally, most drywall corners are not perfectly square. Consequently, alignment of the corner bead with the underlying drywall corner can be difficult. Furthermore, failure to so attach the corner bead to the corner prior to “mud” application can result in slippage or movement of the corner bead from its proper location during such installation. 
     The simplification of the corner bead alignment with the underling drywall corner is often accomplished through the use of relatively complex and/or relatively expensive power tools that assist with alignment while stapling or gluing the corner bead to the underlying drywall The elimination of the use of such tools or the stapling or gluing operation entirely, would be of great value to the drywall installer in terms of time and cost. The mere ability to rapidly achieve corner bead alignment with the underlying drywall corner is of great value for the same reasons, even if stapling or attachment is still performed. 
     OBJECT OF THE INVENTION 
     It therefore an object of the present invention to provide a drywall corner bead that can be easily and accurately aligned with the underlying drywall corner and does not require fastening of the corner bead to the drywall prior to application of the “mud” to avoid movement thereof during “mud” application. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided an improved corner bead comprising an arcuately profiled, elongated central portion having two lateral edges and defining a concave and a convex surface, flanges extending from each of the lateral edges and unitarily formed therewith. The concave surface includes a pair of longitudinal rails extending at about 90° one from the other and along the geometrical centerline of concave surface  26 , that serve to align the corner bead of the present invention with the underlying drywall, without the need for stapling, gluing or otherwise attaching the corner bead to the drywall to prevent relative movement thereof prior to application of the “mud”. Stapling, gluing etc. may, of course, still be used, if desired. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one embodiment of the drywall corner bead of the present invention. 
     FIG. 2 is a perspective view of a second embodiment of the drywall corner bead of the present invention. 
     FIG. 3 is a top cross-sectional view showing the drywall corner bead of the present invention installed on a drywall corner. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1, the corner bead  10  of the present invention comprises an elongated central portion  12  having two lateral edges  14  and  16 . Central portion  12  has an arcuate shape. Extending laterally from edges  14  and  16  are flanges  18  and  20 . According to a preferred embodiment, flanges  18  and  20  have apertures  22  therein to permit penetration of “mud” as described hereinabove. Central portion  12  has an outer convex surface  24  and a concave inner surface  26 . Extending from convex inner surface  26  is a pair of longitudinal rails  28 . 
     In the embodiment depicted in FIG. 1, longitudinal rails  28  are in the form of a “V” whose individual lees  30  and  32  extend at substantially right angles to each other, i.e. the angle θ is about 90°. The base of the “V” in this embodiment is along the geometrical center of concave surface  26 . With this configuration, when corner bead  10  is applied to a drywall corner and rails  30  and  32  applied on opposing surfaces of the corner, corner bead  10  is self-aligning with the corner of the drywall, and no stapling or other fastening of corner bead  10  is required to hold corner bead  10  in the aligned position during application of the “mud”. Stapling may, or course, be used, if desired, but corner bead  10  will be self-aligning during the stapling operation. The length of rails  30  and  32  is not particularly critical to the successful practice of the invention so long as they are long enough to properly contact the underlying drywall corner, but not so long as to interfere with proper application. Lengths on the order of about ¼ to about ¾ inch have been found satisfactory. 
     A second preferred embodiment of the corner bead  10  of the present invention is depicted in FIG.  2 . In this case, all of the elements are essentially the same, i.e. corner bead  10  comprises an arcuately shaped, elongated central portion  12  having an outer convex surface  24 , an inner concave surface  26  and lateral edges  14  and  16  and includes flanges  18  and  20  extending from edges  14  and  16 . Flanges  18  and  20  preferably include apertures  22 . The only distinction between the embodiment of FIG.  1  and that of FIG. 2 being that, rails  30  and  32  instead of being in the shape of a “V” whose bases intersect, their bases are spaced apart. The angle θ between rails  30  and  32 , however, remains at about 90° so that when corner bead  10  is installed over an underlying drywall corner, rails  30  and  32  engage the opposing surfaces of thereof thereby centering or aligning corner bead  10  on the underlying drywall corner. Again, the midpoint between separated rails  30  and  32  is longitudinally along the geometric centerline of concave surface  26 . 
     FIG. 3 shows the corner bead of FIG. 1 installed over a drywall corner. As shown in FIG. 3, corner bead  10  is applied over the joint  40  formed by the intersection of drywall sheets  42  and  44 . Flanges  18  and  20  form contact with drywall sheets  42  and  44  while tabs  30  and  32  are in intimate contact with the approximately 90° outer corner  46  of joint  40  and align corner bead  10  with outer corner  46 . In this position, corner bead  10  is perfectly aligned with outer corner  46  and no lateral movement of corner bead  10  about or laterally relative to corner  46  is possible. 
     While the improved corner bead of the present invention can be fabricated from any number of materials, it is preferred that it be extruded or otherwise formed from a plastic or polymeric material such as PVC (polyvinyl chloride) for reasons of cost and ease of fabrication. Such a process simplifies considerably the integration of rails  30  and  32  into the overall structure as a unitary structure. 
     There has thus been described an improved drywall corner bead that is self-aligning when installed over an underlying drywall corner and will not move during the subsequent application of “mud” thereover. 
     As the invention has been described, it will be apparent to those skilled in the art that the same may be varied in many ways without departing from the spirit and scope thereof any and an such modifications are intended to be included within the scope of the appended claims.