Abstract:
A connector for a main tee of a suspended ceiling grid that has improved self-aligning and connection force properties. The connector has an end tab with a forward portion bent at a lead angle and a receiving pocket with an outwardly flared entrance that, with an opposed identical connector, cooperate to provide smooth horizontal alignment. The end portion, additionally, includes an edge profile that vertically aligns itself with the receiving pocket of the opposed connector. The receiving pocket includes a spring-like resilient wall that limits the assembly force to overcome interference with projecting lock lances even when the connectors are nearly out of dimensional tolerance. The spring-like pocket wall, shape of the lock lance, and reinforcing beads contribute to an improved audible click signaling that a connection has been completed. The lock lance works with a relief groove to augment self-alignment of the connectors.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to improvements in suspended ceiling grid components and, in particular, to end connectors for main runners or tees of such systems.  
         PRIOR ART  
         [0002]    It is difficult to produce a main tee grid connector with previously known designs that is consistently easy to assemble in the field and that will result in a reliable and positive interconnection. Various known end connectors for main runners or tees can be somewhat difficult to install for numerous reasons. Such connectors may not be self-aligning and if they have provisions for self-alignment, their performance in this regard may be marginal at best. Smooth engagement and coupling between end connectors can be obstructed where the configuration of the connector parts have prominent surfaces or projections that interfere with the advance of mating end connectors.  
           [0003]    Typically, main runners are 12′ long and are installed by a technician who, during an installation, grasps the runner, relative to the end being joined to a preceding runner, on the far side of its center. This permits proper balance and allows the technician to be in a suitable position to initially tie the runner up in suspended position. Thus, the technician is at least 6′ away from the joint so that it is difficult for the technician to clearly see the end receiving pocket of the preceding runner. Moreover, from this location, the technician cannot cup the ends to be joined in one hand to align them together. Consequently, there remains in the art, a need for an end connection or splice system that affords improved self-aligning capability.  
           [0004]    A more subtle but sometimes more troublesome problem occurs when the end connectors are out or nearly out of dimensional tolerance due to variations in material stock, tool wear or other manufacturing conditions. In this circumstance, the forces required to connect the ends of the runners may vary from one runner to the next so that the technician installing the grid is confounded by not knowing for sure if a good connection is being made. Additionally, these dimensionally marginal parts can require excessive assembly force, again to the distraction or frustration of the technician.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention provides an end connector or “splice” for main runners or tees that has improved self-aligning properties and that provides greater consistency and comparatively lower levels in the force required to complete a connection. The connector of the invention includes an end tab that is configured to align itself with an identical opposing connector to which it is being joined. The connector further includes a resilient pocket receiving area for the end tab of the opposing connector that avoids both high assembly force levels and widely varying assembly force levels in the installation of one runner to the next.  
           [0006]    In the illustrated embodiment, the end tab has elements for aligning itself to the receiving pocket of an opposed connector in both the vertical and horizontal directions. The vertical alignment feature is advantageously effective from a condition where the end tab misalignment is physically limited by the flange of the opposed tee runner. This structure enables a connection to be made where the end tab is first laid on the flange of the opposing previously installed runner and then is simply subjected to an endwise force by the installer. The leading profile of the end tab is effective, in the vertical location established by the flange of the opposed tee, to cam the end tab towards alignment with the mating connector. The vertical self-aligning character of the end tab is augmented by a lock lance element that registers with a groove in an opposed connector end tab. The vertical alignment action of the lock lance is assisted by horizontal alignment elements of the connector. The horizontal alignment elements of the connector comprise a lead angle formed by bending the forward portion of the end tab out of the plane of a main portion of the end tab and an outwardly flared entrance to the end tab receiving pocket. These lead angle and flared entrance elements provide relatively large, smooth camming surfaces, as compared to edge areas, that improve the smooth functioning of the connector. The lead angle of the end tab and outward flare of the opposed connector are readily inter-engaged for horizontal alignment. Additionally, these lead angle and outward flare components avoid any direct edge-to-surface contact between these components so that smooth sliding action occurs when the lock lance moves out of the relief groove of the opposed connector in the late stages of the assembly movement where the potential interference between the connectors is greatest.  
           [0007]    The disclosed connector is arranged to produce an audible click when a connection is completed and, therefore, signal the same to the installer technician. The repeatability and loudness of the click is the result of several structural elements of the connector. The lock lance has a locking edge configured to cause it to snap over a mating edge of the opposed connector without interference with the locking edge of the opposing connector. The resilient character of the receiving pocket of the opposed connector imparts kinetic energy to the end tab when its lock lance snaps over the locking edge of the opposed connector. The end tab, additionally, has stiffening ribs which increase the sharpness of the click made by the snap-over of the lock lance. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a perspective view of end portions of two main runners or tees shown prior to their endwise assembly or connection;  
         [0009]    [0009]FIG. 2 is a side elevation of an end portion of a main runner or tee and an associated connector;  
         [0010]    [0010]FIG. 3 is a fragmentary cross-sectional view of the connector area taken along the line  3 - 3  in FIG. 2;  
         [0011]    [0011]FIG. 4 is a cross-sectional view of the end tab taken along the line  4 - 4  in FIG. 2;  
         [0012]    [0012]FIG. 5 is a fragmentary cross-sectional view of the end tab taken along the line  5 - 5  in FIG. 2;  
         [0013]    [0013]FIG. 6 is a side elevational view of an opposed pair of connectors prior to their connection;  
         [0014]    FIGS.  6 A- 6 D show progressive stages of assembly of the opposed connectors and horizontal alignment thereof as viewed from the top of the connectors;  
         [0015]    [0015]FIG. 7 is a side elevational view of the connectors in their assembled state; and  
         [0016]    [0016]FIG. 8 is a side elevational view of a pair of connectors in a self-aligning condition both in the vertical direction and in the horizontal direction, the latter corresponding to a stage between that shown in FIGS. 6A and 6B. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    Referring now to the drawings, there is shown an end portion of a main runner or tee  10  of a general type commonly used for suspended ceiling grid systems as known in the art. Typically, such main runners or tees  10  are combined with cross runners or tees (not shown) to create a suspended grid work. In the illustrated example, the main tee  10  is made of two formed metal strips  12 ,  13  typically of steel, although other material such as aluminum can be used. One of the strips  12  forms an upper hollow bulb  14 , a double wall web  16 , and oppositely extending flanges  17  all integral with one another. The strip  12  can have, for example, a thickness of 0.012″ to 0.027″ depending on the application. The other strip  13  lies under the flanges  17  and is wrapped around the distal edges of the flanges  17  to lock the strip  12  in its tee shape, conceal the seam between the flanges  17  and provide a smooth appearance for a lower face  18  of the tee  10 ; the lower face  18  of the strip  13  typically is painted for appearance purposes. The lower strip  13  is a suitable material, typically steel, but can be other materials such as aluminum. Holes  19  through the web  16  enable the tee  10  to be suspended by wire or other means as is known in the art. It will be understood that the runner  10  can have various other shapes, besides a conventional tee shape as is known in the art.  
         [0018]    The runner or tee  10  has an end connector or splice  20  that, in the illustrated case, is integral with the web  16 . It will be understood that certain features of the invention can be applied to connectors that are formed in a single web wall or layer or are formed wholly or partially as separate elements that are joined to the main parts of a runner with rivets or other means as is known in the art. As is conventional, a runner or tee  10  will have a connector  20  at each end.  
         [0019]    The connector  20  includes an end tab  21  and an end tab receiving pocket  22  that, as explained below, cooperate with an identical connector in the manner of a “handshake” to connect the opposed ends of two aligned tees or runners  10  together. The end tab  21  and pocket  22  are die cut and formed by suitable stamping dies. The end tab  21  projects from an imaginary vertical plane perpendicular to the lengthwise direction of the tee  10  and located where the lower face  18  terminates, this location being the nominal end of the tee proper. Major or “land” portions of the end tab  21  are planar and are offset from the plane of the center of the tee  10  (where the walls of the web  16  abut) by a distance at least equal to the thickness of the stock forming the walls of the web (i.e. the thickness of one web wall). As will be understood, this will allow a face of an end tab  21  to mate with the face of another end tab substantially at the mid-plane of each of the tees  10  being joined or connected.  
         [0020]    The side profile of the end tab  21  is generally rectangular having two parallel horizontal edges  23 ,  24  at the top and bottom, respectively. A plane of an end portion or lead angle  26  is at an acute angle of about 35°, for example, from the plane of the end tab proper to the side of the tee  10  from which the end tab is offset.  
         [0021]    A lock lance  27  is stamped into a forward area of the end tab  21  at mid-height of the end tab. The lock lance  27  projects from the plane of the end tab proper to the same side to which the lead angle end portion  26  is bent and from which the end tab is offset. The lock lance  27  is bulbous and preferably has the general shape of a longitudinal half of a bullet. A locking edge  28  of the lance  27  is originally cut by a stamping die from a line common to an end edge  29  of a relief and alignment groove  31 . The lock lance edge  28  is originally cut in the plane of the end tab proper on a line that is curved on a radius or radii centered away from the main tee proper, i.e. this cut line is convex with reference from the main tee proper. The result of this curved cut line geometry, when the lock lance is caused to protrude from the plane of the end tab proper, is that the free locking edge  28  forms an angle when viewed in a vertical direction as in FIG. 3 that is about 90° or less. Thus, the apex or mid-point of the edge  28  furthest from the plane of the end tab proper is, ideally, situated at least as far back from a front edge  32  of the end tab  21  as remaining parts of this edge  28 .  
         [0022]    The relief groove  31  is vertically aligned with the lock lance  27  and extends longitudinally rearwardly from the lock lance to a somewhat rounded end  33  adjacent the receiving pocket  22 . The relief groove  31  has a depth about equal or more than the height of the lock lance  27  and a width moderately larger than that of the lock lance.  
         [0023]    A pair of beads or small ribs  34  extending longitudinally from a bend line  36  between the lead angle end portion  26  and end tab proper are stamped into the material of the end tab and project to a side of the end tab opposite that of the lock lance  27 . The beads  34  are parallel to the edges  23 ,  24  and extend rearwardly somewhat beyond the lock lance  27  and thereby stiffen the end tab  21  across a weakened line existing where it is cut to form the lock lance edge  28  and groove end edge  29 .  
         [0024]    The tab receiving pocket  22  comprises a wall  37  and an opening  38 . In the illustrated case, the wall  37  and opening  38  are rectangular and are produced by lancing or cutting the stock of the web  16  along parallel horizontal lines or cuts  39  and a vertical line or cut  42 . The pocket wall  37  is integral with the web  16  along a side  43  proximal to the web  16  while the remainder including a distal edge  44  and top and bottom edges  46 ,  47  are cut free of the web. With particular reference to FIG. 3, the wall  37  is stamped into a non-planar configuration that, for the most part, is spaced laterally outward of the web  16 . In this context, the plane of the web  16  is defined as the space occupied by the web proper. A region of the wall  37  proximal to the web  16  forms a hollow by virtue of a step portion  48  bent away from the plane of the web  16  and an intermediate portion  49  bent slightly back toward the plane of the web. The distal end of the pocket wall  37  is formed with an outwardly flared portion  51  at an angle to the plane of the web  16 . The wall  37 , when viewed in FIG. 3 is re-entrant at the zone of a bend line  52  between the outwardly flared portion  51  and intermediate portion  49  so that this zone  52  is exclusive in its proximity to the plane of the web  16  as compared to adjacent parts of the wall  37 .  
         [0025]    The connector  20  is adapted to mate with an identical connector as shown in FIGS.  6 A- 6 D and FIG. 7. In this manner, successive main tees or runners  10  are joined together end-to-end to span a room or other space in which a suspended ceiling is to be constructed. An important feature of the connector  20  is its ability to self-align itself to a mating connector. By way of example, FIG. 8 shows a condition where two connectors  20  are being joined together and are initially out of vertical alignment. In the condition of FIG. 8, the connector  20  of one tee  10  is resting on the upper side of a flange  17  of another tee. This condition most typically would be where the higher tee (on the left in FIG. 8) has previously been installed and the lower tee (on the right) is being joined to the previously installed tee. Inspection of FIG. 8 reveals that a lower inclined, curved part  60  of the lead edge  32  has a portion slightly higher than the lower edge of the pocket opening  41  of the opposed connector. Similarly, but not shown, on the opposite side of the tees in FIG. 8, an upper inclined, curved part  61  of the lead edge of the relevant end tab has a portion below the upper opening edge  39  of the connector  20 . With the connector  20  urged horizontally or laterally towards the opposite connector, the lead angle end portion  26  slips into the pocket opening  38  of the opposed connector. Longitudinal force applied to the tee  10  being installed causes the inclined edge  60  working against the pocket opening edge  41  of the opposed connector to cam the connector  20  upwardly relative to the opposed connector and thereby self-aligns the connector to the opposed connector. Other shapes for the rounded edge parts  60 ,  61  capable of shifting the connector up or down when engaging the pocket structure are contemplated. This camming action is augmented by two other camming functions. Cam-like inter-engagement between the lead angle end portion  26  and the outwardly flared portion  51  of the pocket wall  37 , at each set of these elements, biases the connectors  20  laterally or horizontally towards one another when the tees are forced axially or longitudinally towards one another. When the lock lances  27  inter-engage with the opposed relief grooves  31 , these elements, in response to the lateral or horizontal bias developed by the sets of lead angle end portion  26  and pocket wall flare portion  51  cam the connectors  20  vertically, again in self-alignment action. The result of these combined camming actions is that the connectors  20  are positively self-aligning and are comparatively easy to interconnect.  
         [0026]    The relief groove  31  avoids significant interference between the connectors due to the projection of the lock lance  27  until after they have been effectively aligned by the end tabs  21  being substantially received in opposed pocket holes or openings  38 . When the lock lances  27  reach the end  33  of the respective relief grooves  31  of their opposed connector  20  continued advance of the tee being installed requires the pocket walls  37  to momentarily resiliently deflect laterally outwardly to allow the lock lances to slide out of the ends of the grooves and over a short distance on the surface of the end tab proper until it passes the cut or edge  42  formed when the pocket wall  37  was made. The reentrant character of the wall  37  allows the surface area of the bend line  52  to exclusively contact the opposing end tab  21  (between FIGS. 6C and 6D) and assures consistent spring action. At this point, the lock lances  27 , under the influence of the spring-like force developed by the deflected resilient pocket walls  37  snap longitudinally behind the edges  42  of the opposed connector thereby completing a connection or splice.  
         [0027]    A beneficial result of the disclosed structural features of the connector is that an audible click is produced when the lock lance edges  28  pass over the edges  42  of the pocket openings  38  allowing the end tabs  21  to snap against one another. The click signals the installing technician that a connection has been completed. The loudness of this click is due in part to the geometry of the lock lance edge  28  which is, as discussed, 90° or less, thereby avoiding a condition where if this edge were in a plane greater than 90°, it would slide down the opposed locking edge  42  and mute the click. The beads  34 , by stiffening the end tabs  21  in the area of the lock lances  27  add to the loudness of the click.  
         [0028]    The lead angle end portions  26  and the flared portions  51  of the pocket walls ensure that only surface-to-surface contact occurs when the greatest interference arises in the connection sequence as the lock lances slide over the land areas between the relief grooves  31  and the locking edges  42  of the openings  38 . Contact between the front edge  32  of an end tab  21  or the distal edge  44  of the pocket wall  37  could greatly increase the frictional resistance between the connectors. In part, the re-entrant character of the wall at the bend line  52  avoids such edge contact. With the periphery of the pocket wall, specifically the edges  44 ,  46  and  47  (apart from where it is joined with the web proper), being free of connection with other parts of the connector, the pocket wall acts as a resilient spring. Consequently, the force to deflect it laterally for passage of the lock lance out of a groove  31  and over the adjacent land to the opening edge  42  is limited. In turn, the force to effectuate a connection is moderate and not prone to vary widely when the connectors  20  are nearly out of tolerance because of material thickness variation, tool wear or other manufacturing conditions. Such wide variation is known to occur in prior art connector designs and is found to be very objectionable to professional installation technicians. The beads  34 , in addition to reinforcing the end tab  21  and improving the audible click, serve to avoid excessive friction during a connection where burrs may exist on edges of adjacent parts.  
         [0029]    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.