Patent Application
20130333317
The invention relates to suspended ceiling grid construction.
Suspended ceilings typically include a rectangular metal grid on which are supported ceiling tiles or drywall panels. The commercial construction industry is highly competitive and, accordingly, the cost of building materials in this sector is important. Raw material consumption, particularly material without a large recycled content, is likewise a concern for preservation of the environment. Accordingly, there is a need for suspended grid products that consume less material and can be economically produced.
The invention is embodied in a suspended ceiling grid runner having a material saving open web construction. The inventive grid runner is an elongated assembly of main parts comprising a lower face flange, an upper reinforcing bulb and an open web extending vertically between the flange and bulb. The web has a novel serpentine configuration extending alternately from the flange to the bulb and from the bulb to the flange. The web is fixed to the flange and bulb at each juncture. By virtue of its serpentine configuration, the web is characterized by open spaces along the length of the runner that represent significant material savings. In the preferred runner construction, the flange and bulb are roll formed sheet metal strips while the web is a flat, stamped strip. These components are assembled together in a press that clinches the parts together at locally overlapping points.
The web strip is sheared from sheet stock, preferably supplied from a coil. The shear has specially shaped cutting edges corresponding to the serpentine form of the web. By way of example and not limitation, the web sheet stock is fed to a shear in ¾ in. increments while producing a web 1-⅜ in. high without scrap. The inventive runner is advantageously assembled in a press operation that also performs the traditional cross tee slot and hanger hole punching.
A grid runner 10, illustrated in
Preferably, the bulb 11 and flange 12 are each made by roll forming a single sheet metal strip, usually steel, with conventional techniques well known in the industry. The flange 12 can be pre-painted prior to roll forming on a side visible when installed. The bulb is hollow with a circular cross section. The bulb 11 can be formed with various other cross sectional shapes such as an oval, rectangle, triangle or other polygon. The bulb 11 is preferably formed with the hollow space essentially closed. The bulb 11 includes a depending rib 16 that lies in a vertical plane bisecting the hollow part, the latter comprising the bulb proper.
The illustrated flange 12 has the shape of an inverted short tee. In use, the flange commonly becomes the visible face of the grid runner 10 where the grid runner is used with ceiling tiles. A horizontal part 18 of the flange 12 extends widthwise, i.e. transversely to the longitudinal direction of the runner and symmetrically about a vertical upstanding stem or rib 19. One side 21 of the horizontal flange part 18 is a double wall or two ply construction while an opposite side 22 is a single wall with a folded back hem 23 at an edge distal from the rib 19. In ordinary use of the runner 10 in a suspended ceiling, edges of rectangular ceiling panels or tiles rest on upper surfaces of the flange horizontal part 18.
The web 13 is a flat sheet metal stamping that serves to hold the bulb 11 and flange 12 in spaced relation in the manner of a parallel chord truss. Referring to
In profile, the web 13 can be described as having crests 31 and valleys 32 that, in the illustrated case, are flat at their respective top and bottom edges. The serpentine pattern of the web 13 allows the web to span, from the outside edges of the valleys 32 to the outside edges of the crests 31 a distance of 1-⅜ in., for example, while the stock need only be fed ¾ in., for example, to produce this span. When assembled, the web crest flats and valley flats can abut the bottom of the bulb 11 and top of the single ply flange side 22, respectively.
The grid runner 10 is assembled in a press of a length adequate to span the length of the grid runner. The disclosed grid runner construction is ideally suited for main runners which are nominally 12 ft. long or industry metric equivalent. When the runner 10 is this long, it is practical to use 2 or 3 web sections 33 arranged end to end. Making the full length web 13 from the sub-parts or sections 33 enables the use of light gauge coil stock of a conventional width. Preferably, the web sections 33 are slightly overlapped at their adjacent ends when assembled into a grid runner 10.
With reference to
It is envisioned that a material savings up to about 30% can be obtained with the serpentine web 13 as compared to constructions having a conventional web with no large open areas. While the foregoing disclosure involves a main runner or main tee, the serpentine open web construction can be used to construct cross runners. The flange can have different cross sectional configurations other than the illustrated simple tee. Such configurations can include a downwardly open channel, sometimes referred to as a screw slot runner.
It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.
