Building panel
RELATED APPLICATIONS 
     Applications Serial No. 875,524 and Serial No. 875,533 filed of even date herewith by the present applicant are directed to a roof structure and to a panel mounting clip as described herein. 
     BRIEF SUMMARY OF THE INVENTION 
     It is the purpose of this invention to provide a building panel design which enables the panels to be joined and form a membrane that is structurally sound, economical to install, flexible enough to accommodate differential dimensional changes after installation, and resistant to disruptive forces tending to disassemble the panels prior to final assembly. 
     In accordance with the invention, channel shaped panels are provided with opposite sidewalls that have flanges shaped to nest together and interlock when panels are laid side by side prior to seaming. Disruptive loads on one panel can be transferred via the interlocks into other interconnected panels so that the integrity of the panel assembly can be maintained prior to seaming. In roof structures, the panel interlocks are adapted to receive and be interlocked with panel mounting clips that are fastened to the roof purlins. In preferred form, the mounting clips include flexibility features that permit movement of the panels relative to the purlins while maintaining their attachment to them. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified perspective view of a building in the process of construction showing an environment in which a metal building panel embodying the invention is used in forming a roof structure; 
     FIG. 2 is a broken away perspective view, on an enlarged scale as compared with FIG. 1, showing how building panels according to the invention would be installed on the roof of the building of FIG. 1; 
     FIG. 3 is a broken away perspective view looking down on the top of a panel constructed in accordance with the invention; 
     FIG. 4 is an enlarged cross section along the line 4--4 of FIG. 3; 
     FIG. 5 is a perspective view similar to FIG. 2 but showing the manner in which adjacent panels are interlocked; 
     FIG. 6 is a reduced size cross elevation with parts omitted of adjacent panels in the process of being interlocked, substantially as they appear in FIG. 5, one panel mounting clip being shown in phantom lines to indicate that it is fastened at that position after the panel to which it is to be attached is hinged down to a horizontal position; 
     FIG. 7 is an enlarged broken away perspective view similar to FIG. 2 showing the panel mounting clip, panel, and purlin; 
     FIG. 8 is an enlarged cross section through one side of a typical panel with a panel mounting clip attached to it and to a purlin; 
     FIG. 9 is an enlarged side elevation of the panel mounting clip shown in previous Figures; 
     FIG. 10 is an end elevation of the clip shown in FIG. 9; 
     FIG. 11 is a cross section through a panel - panel mounting clip - panel joint prior to seaming; 
     FIG. 12 is a cross section of the joint of FIG. 11 after seaming; 
     FIG. 13 is a cross section through a panel to panel joint prior to seaming; and 
     FIG. 14 is a cross section through the joint of FIG. 13 after seaming. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a building 1 with a low profile roof structure 3, sidewalls 5, an end 7, and a floor 9. The roof structure comprises a large number of metal panels 11, embodying the invention, which are substantially identical in shape, elongated, and laid side by side. In final assembly they are seamed together so that each side 13 of the roof becomes substantially a one piece membrane formed of a series of integrated panels. The sidewalls 5 are illustrated as consisting of panels 15 erected side by side and fastened together but other sidewall constructions can be used with the roof structure 3 of this invention. It is preferable, however, that the sidewalls be erected prior to the roof structure since, as seen best in FIG. 2, the overhang of previously installed building panels 11 would interfere with erection of the sidewall panels 15. 
     The building 1 has any suitable framework, such as arches, formed by the vertical members 17 that support the inclined transverse roof beams 19. The beams 19 support the horizontal longitudinal purlins or rafters 21 of the roof structure. The top surfaces 23 of the upper purlin flanges 25 define roof planes for the roof sections 13 that are plumb and square and they support the panels 11 and panel mounting clips 27. 
     In accordance with the invention, the building panels 11 have a special cross sectional configuration which not only strengthens them but enables adjacent panels to be movably interlocked or hinged and, later, to be tightly joined together in a common mechanical seam. The mechanical interlocks between adjacent panels in conjunction with the clips 27 hold them substantially in place while the remaining panels are being run and until seaming can be finished thereby minimizing the possibility of their disruption due to gusts of wind, etc. 
     Each panel 11 comprises a central bottom wall portion 31 which may be flat, as shown, or reinforced in a suitable way such as by a series of transverse embossed ribs (not shown) pressed into it. The panel has opposite sidewalls 33 and 35 extending upwardly and outwardly from the bottom 31 at angles of substantially 60° to the horizontal, i.e., plane defined by the bottom 31. The sidewalls 33 and 35 are substantially mirror images of each other, except for top flanges 37 and 39, respectively, and like features are therefore given the same reference numbers. Thus, the sidewalls 33 and 35 include outwardly slanted vertical bottom wall sections 41 having top ends which are joined by horizontal shelf sections 43 to the bottom ends of outwardly slanted, vertical, intermediate wall sections 45. Horizontal rims 47 extend outwardly from the top ends of the wall sections 45 and terminate at the bottom ends of seaming ribs 49 and 51 that form upper panel sections that extend, preferably, at right angles to a plane defined by the bottom wall 31. The ribs 49 and 51 define the maximum widths of the panels. Ribs 49 are slightly higher than the ribs 51 so that flanges 37 will fit over the tops of flanges 39. 
     The top flange 37 extends outwardly from the top of its rib 49 at an angle of substantially 60° to it (about 30° to the horizontal or plane of bottom 31); and the top flange 39 extends inwardly from the top of its rib 51 at an angle of substantially 60° to it. The top flange 37 is a little wider than flange 39 and has an inner section 53 that extends outwardly and downwardly at an angle of substantially 60° to its rib 49 (about 30° to the horizontal) and an outer section or lip 55 that extends inwardly and downwardly at an angle of substantially 60° to the inner section 53 and rib 44 (about 30° to the horizontal and 120° included angle) for a distance substantially as indicated by the dimensional relationship shown in the drawings (e.g. FIGS. 4 and 11-14) so that a part of it will be vertically below a flange 39 after installation. The top flange 39 has an inner section 57 that extends inwardly and downwardly toward bottom 31 at an angle of substantially 60° to its rib 51 (about 30° to the horizontal) and an end section 59 that is doubled back toward rib 51 to form a reversely bent bulb-like end edge portion for the flange 39. It will be noted that suitable radii are provided at the various corners and bends and that the panels 11 are of a shape that can be roll formed from sheet metal in accordance with known methods and using roll stand equipment that is commercially available. The particular angles disclosed with respect to flanges 37 and 39 have been found to be preferable in that they facilitate assembly while maintaining interconnection. 
     Referring to the panel mounting clip 27, best illustrated in FIGS. 7-10, the construction of this member enables it to assist in holding the panels 11 in place after they are laid. It includes means that cooperate with the interlocked panels to permit the panels to expand and contract relative to the purlins 21 in response to pressure differentials and changes as well as temperature differentials and changes during the life of the roof thereby minimizing roof stressing induced by differential loading. The panel mounting clip 27 is preferably formed of sheet metal and has a channel shaped base member 63 with a lower horizontal flange 65 that has a pair of openings 67 in it whereby the clip may receive screw fasteners or the like 69 for attaching its bottom flange 65 to the top flange 25 of a purlin 21. The member 63 has a vertical web 71 and several gussets 73 may be pressed in it and in the bottom flange 65 at the corner between the web 71 and the flange 65 to provide rigidity to the bottom end of the clip 27. The top flange of the base member 63 has a central section 75 which is parallel to the bottom flange 65 but which is bent to extend in the opposite direction. On either side of the top flange 75 at the opposite ends of the member 63 are a pair of top end flanges 77 which extend in the same direction as the bottom flange 65 and are parallel to it. The flanges 75 and 77 provide shelves which fit beneath the rims 47 of the panels 11 to provide means on which the panels may be supported if their weight is not carried directly by support of bottoms 31 on the purlins. 
     The web 71 has a horizontal slot 79 extending through it which is substantially coextensive with the flange 75. A flap-like tab clip 81 is mounted on the web 71 in the slot 79 and is capable of sliding movement from one end of the slot to the other. Tab clip 81 is preferably formed of thinner metal than is the base member 63 and is somewhat resilient so that its vertical web portion 83 is biased toward the surface of web 71 but can also move transversely away from it in the direction of the arrow 85 (see FIG. 10). The bottom of the tab clip has a special resilient loop configuration which includes a reverse bend portion 87 that extends upwardly after passing through the slot 79 and is shaped to press against the back of the web 71 just as the bottom of the web 83 presses against the front side of web 71. The clip metal is reversely bent downwardly in a section 89 that extends to below the bottom of the slot 79 for a distance substantially equal to the length of the reverse bend section 87. The section 89 is then reversely bent into a section 91 corresponding to section 87 which engages the back side of the web 71 and extends through the bottom side of the slot 79 where it is reversely bent downwardly in an end section 93 for the tap clip 81 that engages the inside face of the web 71. The reverse bend sections 87 and 91 together with the section 89 form a resilient loop-like holding means 95 for the tab which clamps it to opposite sides of the web 71 but permits it to slide in the slot 79 between flanges 77. The horizontal spacing of the back section 89 from the reverse bends 87 and 91 provides a spring action that tends to hold the tab clip 81 in a vertical position as shown in FIGS. 8 and 10 but also enables it to be moved away from the web 71 in the direction of the arrow 85. Since the tab clip 81 is of relatively thin metal it can also be bent resiliently to some extent in the direction of the arrow 97. 
     While the tab clip 81 is capable of longitudinal movement with respect to the base member 63 it does have a center position along the midline of the member 27 and is yieldably held in this position by means of a dimple 99 that is embossed in the web 71 and adapted to seat in a hole 101 formed in the tab web 83. Substantial force tending to move the clip 81 in one direction or another along the slot 79 will overcome the spring pressure of the holding section 95 and enable the web 83 to ride over the dimple 99. 
     The top end of the tab clip 81 has a hook-like flange 103 which is very similar to panel flange 37. Thus, it has a section 105 that extends outwardly and downwardly at an angle of substantially 60° to the section 103. The height of the flange 103 above the plane of the top surfaces of flanges 75 and 77 is a little more than that of a flange 39 above a rim 47. The transverse length of the flange 103 is also a little more than that of flange 39. The flange dimensional relationships enable flanges 103 to snugly fit over and its end lip 107 to hook on to flanges 39 and the panel flanges 37 to fit over, hinge around, and hook on to the combined flanges 39 and 103 (FIGS. 11-12) as well as single flanges 39 (FIGS. 13 and 14). 
     In practical application of the invention, the framework of the building 1 is first erected followed by the side walls 5. After this is done, the panels 11 may be laid on the purlins 21 starting from the left and moving toward the right end of the roof section 13. Ignoring special procedures known to those in the art for handling the structure at the ends of the roof section, a panel 11 is laid across the purlins 21 and may be allowed to rest there under the force of gravity and resistance of friction. If desired, a simple screw or two (not shown) may be passed through the bottom 31 and threaded into a purlin flange 25 to provide a means for temporarily holding the panel in place until the panel mounting clips 27 are installed. After a panel 11 is thus laid on the purlins 21, the panel mounting clips 27 are lined up with the right side wall 35 of the panel so that the flanges 75 fit under the rim 47, the tab clip 81 abuts the upper section 51, and the top flange 103 and hook lip 107 extend over and around the flange 39 on the side wall 35. The actual connection can be made by hooking the flange 103 on the flange 39 and hinging the clip 27 around to the vertical position indicated. When this is done, holes are drilled in the purlin flange 25 in alignment with holes 67 in the bottom flange 65 of the panel clip 27. Screws 69 are then threaded into these holes in the purlin to thereby firmly anchor the panel clips to the purlin. This, of course, also anchors the side wall 35 of the panel 11 to purlin so that it cannot move upwardly away from it. 
     As seen best if FIGS. 5 and 6, the next step in the assembly procedure is to attach another panel 11 in side by side relationship to the panel that has just been anchored in place by panel mounting clips 27. This is done by interconnecting the side wall 33 of the second panel to the side wall 35 of the first and anchored panel. More particularly, it is done by placing the flange 37 over and around the flange 39 so that the stationary flange 39 is nested inside of the flange 37. This interconnection is accomplished by tilting the panel 11 that is being attached at an angle to the horizontal so that the lip edge 55 can fit in the corner of the flange 39 as shown by the phantom lines in FIG. 13. When this relationship has been accomplished between the flange 37 and the flange 39, the panel 11 can be hinged in a clockwise manner until its bottom 31 comes to rest against the surfaces 23 on the purlins 21. The particular angles used on the panel flanges make this interconnection relatively easy to achieve. At this point the relationship between the flanges 37 and 39 will be substantially as shown in full lines in FIG. 13 in the cross sections where there is no panel clip 27 and substantially as shown in FIG. 11 at cross sections where there is a panel mounting clip 27. It will be seen that the lip 55 on the flange 37 lies vertically below the rebent end 59 of the flange 37 and consequently the two panels are interconnected in such a way that it is quite difficult to separate them by simple movements of one relative to the other, such as might be caused by wind gusts, etc. It is unlikely that the second panel 11 will be disconnected or separated from the anchored panel 11 prior to seaming of the joint between them unless there is also angular unhinging movement of it to unhook its flange 37 from the mating flange 39. 
     After the second panel 11 has been hooked to and hinged around the anchored panel as just described, panel mounting clips 27 are hooked to its side wall 35 and secured in place by bolts 69 as already described for the first panel. This process of hooking a panel being added to the roof section to one already anchored on the roof section, hinging it down until it rests on the purlins 21, fastening the panel mounting clips 27 to the side wall 35 of the panel and then to the purlin 21, is repeated until all the panels 11 that it is desired to install are in place. It will be noted that in this condition the panel mounting clips 27 together with the loose hook type interlock between flange pairs 37 and 39 will integrate the panels so that they in fact form a unitary though flexible roof structure 13. This flexibility is then materially reduced by running a suitable seaming tool along the upright upper vertical rib sections 49 and 51 to bend the flanges 37 and 39 against the inside face of upper section 51 on side wall 35 to achieve the compressed, interlocked final assembly shown in FIGS. 12 and 14. When this is done the lip 107 of the panel mounting clip tab 81 may in some structures be flattened out, as seen by comparing FIGS. 11 and 12, but this has no undesirable effect since it is apparent that the clip 27 still serves to resist movement of the joint in an upward direction away from the purlins 21. It does have a beneficial effect in that it makes it somewhat easier for the tab 81 to move horizontally relative to the upper sections 49 and 51 of adjacent panels. Such relative movement is, as previously mentioned, accommodated by the slot 79, the spacing between flanges 77, the dimple 99, and the flexible holding means 95 of the panel clip construction 27 and permits differential force systems introduced by temperature changes, pressure changes, etc. between interconnected panels to dissipate themselves in relative movement of the panels rather than in deformation or buckling of the panels. The resiliency of the tabs 81 also permits the interconnected panels 11 to have flexibility as a roof membrane relative to the purlins 21 and structure 17 and 19. 
     Thus, the building panel of this invention enables a roof construction to be assembled that is sound of structure, economical to install, flexible enough to dissipate differential stress systems, and resistant to disruptive forces prior to as well as after complete final assembly. Modifications in the specific features shown and described in the application and use of the panels may be made without departing from the spirit and scope of the invention.