Screen frame having corners under compression

#The present invention relates to building materials generally, and more specifically to frames suitable for use in ventilation screen assemblies.

#Ventilation screen frame assemblies are well known. Joining four sections of roll-formed or extruded screen bar material, using four corner keys to attach each pair of consecutive frame members forms a typical frame.

#U.S. Pat. No. 3,097,684 to Le Tarte shows an alternative method of forming a screen frame using a single elongated piece of screen bar stock. Four V-shaped cuts are cut partially through the body, each V-shaped cut leaving an edge of the body uncut. Each V-shaped cut subtends an angle of 90 degrees. The body is folded about each uncut edge so that the ends of the body meet along one side of the frame. The ends of the body are joined to form a closed frame.

#FIG. 1 is a side elevation view of an exemplary screen bar being formed by an exemplary embodiment of a method according to the invention.

#FIG. 2 is an isometric view of a portion of the screen bar of FIG. 1.

#FIG. 3 is a plan view of the screen bar of FIG. 1, folded to form a frame.

#U.S. patent application Ser. Nos. 09/997,737, filed Dec. 24, 1997 (now U.S. Pat. No. 6,279,644, issued Aug. 28, 2001) and 09/379,102 filed Aug. 23, 1999 (now U.S. Pat. No. 6,331,223, dated Dec. 18, 2001) and PCT International Application No. PCT/IB00/01716, filed Aug. 23, 2000, and U.S. Provisional Patent Application 60/272,334, Filed Feb. 28, 2001 are incorporated by reference herein in their entireties, as though set forth fully herein.

#FIG. 4 shows an exemplary embodiment of a screen frame assembly 10 according to the present invention. The exemplary assembly includes a hollow body 11 (screen bar) (which may be made of metal) having a mounting surface 16 for receiving ventilation screen material 20. Details of an exemplary screen bar material, and methods and apparatus for attaching screen cloth 20 to the mounting surface 16 of the body (screen bar) 11 are included in the above-identified patent applications that are incorporated by reference. Other screen bar materials, such as solid screen bar, or foam filled screen bar may also be used. Alternatively, the frame fabrication techniques described below may be used in conjunction with a spline type screen cloth insertion technique to form a complete screen-frame assembly.

#The exemplary body 11 has at least three V-shaped cuts 17 (shown in FIG. 1) partially through the body. Each V-shaped cut 17 leaves an edge 15 of the body 11 uncut. The body 11 is folded about each uncut edge 15 (shown in FIG. 3) so that the ends 11e of the body meet at a corner 22. Each V-shaped cut 17 subtends an angle θ that is slightly less than 90 degrees, so that the folded corners 21 are in compression. In the exemplary embodiment, each V-shaped cut 17 subtends an angle of about 89 degrees. The ends 11e of the body 11 are joined into a closed frame, using a corner key 19 or other suitable joining means. Key 19 may be made of conventional materials, including metal or polymers.