Abstract:
A wall molding for suspended ceiling systems has a self-aligning feature adapted to locate one end of a piece being installed on the end of a previously installed piece so that an installation of high quality workmanship is quickly obtained. The self-aligning feature is in the form of a tongue extending longitudinally beyond a faux end and adapted to nest in the previously installed piece. The tongue fits within the spaces between hems on the longitudinal edges of legs of a right angle cross-section and the opposed legs so that the tongue is laterally restrained in the planes of the legs and is longitudinally restrained by abutting end edges.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to improvements in suspended ceiling componentry and, in particular, to an improved wall molding for suspended ceiling systems. 
   PRIOR ART 
   Typically, a suspended ceiling includes a wall molding at the intersection of the wall and plane of the ceiling. The wall molding serves to support the edges of ceiling tiles and serves to conceal these edges to provide a finished appearance. The wall molding, typically, can also support the ends of tees comprising the grid carrying the ceiling tiles. Conventional wall moldings are manufactured as elongated angles, typically being roll-formed from strips of prefinished sheet metal. Premium or commercial grade wall angles can have a reinforcing hem along the free edges of their legs. The wall molding or angle ordinarily is installed at the desired height on a wall by suitable fasteners such as screws, nails, staples or the like. The height may be determined by a chalk line, laser level or other method. In any case, a problem encountered by the installer with conventional wall molding is the difficulty in holding it level and abutted against a previously installed piece and fastening it to the wall all at the same time. The task is also difficult because the manufactured length of the wall molding is considerable in comparison to its transverse dimensions, so that it is not perfectly rigid. 
   Additionally, because of the length of a standard wall molding, it is difficult to register the end of a new piece with the end of the previously installed piece while holding the new piece at or near its mid-length. These difficulties add to the time required to install the wall molding, particularly when care is taken to mount the molding in a straight line at an exact height and in registry with a previously installed length of molding. 
   SUMMARY OF THE INVENTION 
   The invention provides a wall molding with an extension or formation that enables it to self-align with a previously installed piece. The self-aligning feature permits the wall molding to be installed with less time and greater accuracy in positioning when compared to prior art products. With the self-aligning feature of the invention, the wall molding can be easily registered endwise and laterally with a previously installed piece. The self-aligning feature of the invention is capable of vertically supporting and laterally holding the associated end of the wall molding. As a result, the installer is relieved of a need to concentrate on positioning and aligning this end of the molding and can advantageously direct his/her attention to supporting and fastening a mid-length portion of the molding to initially fasten the molding to the wall. 
   In a preferred embodiment of the invention, the self-aligning feature has the form of a right angle extension or tongue created by parts extending from each leg of the wall molding proper, i.e. the main body of the wall molding. The tongue elements or parts are stepped out of but parallel to the planes of their respective legs a distance substantially equal to the thickness of the legs. This step or offset of the alignment or tongue elements allows them to hold the legs of adjacent ends of a pair of moldings in alignment. With the legs held in alignment by the disclosed tongue parts, only a very moderate longitudinal force on the molding is needed to establish and maintain a good end-to-end fit between wall molding pieces that has the appearance of a butt joint. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a somewhat schematic perspective drawing of a workman installing a wall molding constructed in accordance with the present invention; 
       FIG. 2  is a fragmentary perspective overhead view of a suspended ceiling system employing the wall molding of the invention; 
       FIG. 3  is an enlarged fragmentary view of a joint between the ends of a pair of wall moldings showing the alignment feature of the invention; 
       FIG. 4  is a fragmentary plan view of the end of a wall molding including the self-aligning feature of the invention; and 
       FIG. 5  is an end view of the self-aligning feature of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings and in particular to  FIG. 2 , a conventional suspended ceiling system  10  includes a rectangular grid  11  of inverted metal tees  12  on which is carried rectangular or square lay-in panels or tiles  13 . The tees  12  are typically suspended with wires  14  from an overhead superstructure. The edges of the ceiling system, where the ceiling meets the walls, designated  16 , of a building, are finished or trimmed with a wall molding  17 . 
   The wall molding  17  is in the form of a right angle having perpendicular generally planar legs  18  which, in the illustrated embodiment, are of equal width. As is conventional, the wall molding can be manufactured by roll-forming sheet metal, typically steel, which is pre-painted. The legs  18 , at their longitudinal free edges  19 , have a roll-formed hem  21  where the sheet metal stock is bent back over itself to stiffen the edge and provide a finished appearance. The hem  21  of folded over material normally has a width substantially less than the width of its associated leg  18 , so as to leave a gap  22  between an inner edge  23  and the opposite leg  18 . At one end of the wall molding  17 , a longitudinally extending tongue  24  is provided, in accordance with the invention, to afford a self-alignment feature. The opposite end of the wall molding  17  is plain without a tongue and simply sheared across a plane transverse to the longitudinal direction of the wall molding. The tongue  24  in the preferred embodiment is formed integrally as one piece with the main body of the wall molding  17 , i.e. the wall molding proper. The tongue  24  has integral, mutually perpendicular planar parts  26  protecting longitudinally from a respective one of the legs  18  of the wall molding proper. Each tongue part  26  is stepped out of and is parallel to the plane of its respective leg  18  preferably by a distance generally equal to the thickness of the stock forming the wall molding  17 . Relatively small web or bridge elements  27  lying in a common plane transverse to the longitudinal direction of the wall molding  17  form the transition between the legs  18  and the tongue parts  26 . The tongue parts  26  are integrally joined as one piece at a corner  28 . Ideally, the length of the tongue  24 , i.e. the distance it projects longitudinally from the wall molding proper, is less than the width of the legs  18 . The width of each tongue part  26  is, preferably, slightly less than the gap  22  between its adjacent hem  21  and the opposed leg  18 . Corners  29  of the free ends of the tongue parts  26  are beveled or clipped. 
   By way of example, but not limitation, the wall molding has a nominal length of 10 or 12 feet; the legs  18  are ⅞″ wide; and, the thickness of the sheet stock forming the wall molding is between about 0.015″ to about 0.030″. 
   In a typical installation, the wall molding  17  is attached to a vertical wall  16  at a height and orientation where one of its legs  18  lies at the plane of the ceiling system surface visible from below and the other leg  18  extends upwardly in abutting contact with the wall  16 . Typically, the wall molding  17  is attached with screws, nails or other fastening means ordinarily at regularly spaced locations. The elevation of the wall molding  17  can be set by a laser, chalk line or other known technique. Because the usual length of a piece of wall molding  17  is great as compared to the transverse dimensions of the legs  18 , the wall molding is somewhat flexible and, therefore, difficult to maintain relatively straight where it is temporarily supported at only one or two points along its mid-length. This characteristic has made it difficult with prior art wall molding products to quickly and accurately manually position a length of wall molding in proper registration with the end of a previously installed piece of wall molding and in line with the desired location and, at the same time, fix the wall molding in place with a fastener. 
   After the first piece of wall molding  17  has been installed, subsequent pieces are conveniently and quickly installed with the benefit of the invention. The invention facilitates installation of a wall molding  17  such as in a manner represented in  FIG. 1 . An installer  31 , holding the wall molding  17  near its mid-length can lay the end portion associated with the tongue  24  on the plain end of the previously installed piece of wall molding  17 . The installer  31  can then level the new piece out to the desired elevation and, if more than the tongue  24  is overlapping the plain end of the previously installed piece, simultaneously or subsequently pull the piece away from the preceding piece until only the tongue is in overlapping contact with the previous piece. Thereafter, the piece  17  being installed can be lightly forced against the preceding piece to achieve the appearance of a tight butt joint at a transverse faux end plane where the tongue  26  extends from the legs  18 . At this time, the wall molding piece being installed can be readily fixed in place with a fastener near its mid-length while the installer need only support the wall molding with one hand since the previously installed wall molding  17  is supporting and locating the new piece through the medium of the tongue  24 . 
   The geometry of the tongue  24  has certain benefits. The offset of the tongue parts  26  from the planes of respective legs  18  assures that the legs  18  of a pair of joined wall molding pieces are in planar alignment. The tongue parts  26  fit in the space or gap  22  between the hem edge  23  and the opposed leg  18  of the joined wall molding piece thereby producing a laterally locked condition of the tongue in the planes of both legs  18 . The tongue  24 , being shorter than the width of the legs  18 , enables it to remain without modification or removal when a corner joint between perpendicular walls  16  is established between two wall angles. The beveled or otherwise trimmed corners allow the tongue  24  to slide longitudinally in the gaps  22  between the hems  21  and opposed legs  18  without jamming. The limited width of the tongue parts allows the end edge areas  32  of the legs  18  laterally outward of the bridge elements  27  including the ends of the hems  21  to abut the plain end of the mating previously installed piece  17  so that any tendency for the bridge elements  27  of the new piece to ride up over the previously installed piece under a longitudinal compressive force is suppressed. This abutting action is assured because the height of the hems  21  from the plane of their respective legs is greater than the thickness of the leg stock so that the hem end edges of the plain end snag the opposing end edges  32 . 
   The following more fully explains the role of the hems  21  in establishing a positive end-to-end relationship between a pair of wall moldings. The depiction of the area of the hems  21  in the view of  FIG. 5  is somewhat schematic. Generally, it is the practice in the industry that the inside of the bend at the longitudinal edge of each leg that forms the hem has a measurable radius such that a space exists between the hem and the leg proper, at least at and near the bend. The end edges are typically created by a shear blade that moves in a direction transverse to the longitudinal direction of the wall molding and along a line that bisects the 90° angle between the legs  18 . The shear blade can operate from the space included between the 90° spacing between the planes of the legs or from the other side of the wall molding, i.e. the space of the 270° angle between the legs. Depending on the space from which the shear operates, the hems  21  may tend to be permanently deformed towards the leg proper or away from the leg proper. In the former case, the effective thickness of the legs, including the partially flattened hem will normally be more than twice the thickness of the sheet stock. As described above, the bridge elements  27  are proportioned to space the tongue parts  26  a distance equal to the thickness of the material stock from the planes of the legs proper. Additionally, the bridge elements  27  are formed so that they exist mostly and, preferably, exclusively longitudinally rearwardly of the plane of the end edges  32  of the legs and hems. The functional result of the described end edge structure and the bridge element structure is that a longitudinal compressive force between a wall molding piece being installed and the previously installed piece does not produce a camming action by the bridge elements  27  which could otherwise allow the wall molding piece being installed to slip onto and over the previously installed piece. This potential camming action is prevented by abutting contact between the end edges of the wall molding associated with the tongue and the opposing edges of the plain end of an identical wall molding. Even if the tongue  24  and plain ends are misaligned by a distance equal to the thickness of the sheet stock, as might occur if the bridge elements  27  operate as camming elements, the effective thickness at the hems, being more than double the stock thickness, assures that at least portions of the end edges abut so as to prevent over-riding of the tongue end past the plain end. Also, if the tongue and plain ends of a pair of wall moldings being joined are angularly misaligned about their longitudinal axis, one of the end edges  32  will typically catch on the edge of the opposing plain end with the associated tongue part resting in the space or pocket formed by the hem of the plain end. 
   Other known wall moldings with cross-sections different than the illustrated right angle, equal leg width molding can be provided with the self-alignment feature of the invention. For example, the legs can have unequal widths, e.g. 1″ by 1½″ and/or the cross-sections can be modified J or C-shapes, or can be stepped. In some instances, a leg can have a width as much as about 1½% of the length of the molding. Where desired, a wall molding incorporating the invention can be formed of other suitable materials and processes besides roll-formed sheet steel, such as roll-formed sheet aluminum, aluminum extrusion, or plastic extrusion of polycarbonate or the like. 
   It should be evident that this disclosure is by way of example and that various other 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.