Abstract:
There is provided a method of attaching bracket apparatus to a curtain wall mullion having a fastening channel for receiving screw-threaded fasteners for a bracket element having upper and lower attachment ports. The method comprises the steps of: a) positioning the bracket element on the fastening channel so that a longitudinal opening of the channel is blocked along the longitudinal extent of the bracket element, and providing upper and lower blocking elements within the fastening channel so that the upper and lower attachment ports are in between the upper and lower blocking elements; and b) forcing an adhesive into one of the said upper and lower attachment ports until it appears in the other of the upper and lower attachment ports. There is also provided curtain walling bracket apparatus for use in such a method, and curtain wall mullion apparatus wherein said curtain walling bracket apparatus is attached to a curtain wall mullion using said method.

Description:
[0001]    The present invention relates to a method of attaching bracket apparatus to a curtain wall mullion, curtain walling bracket apparatus for us in such a method, and curtain wall mullion apparatus having the curtain walling bracket apparatus installed according to the said method. 
       BACKGROUND OF THE INVENTION 
       [0002]    It has been a long standing issue within the curtain wall industry to have the ability to easily and economically attach an external bracket to a curtain wall mullion, and which can then offer a high load capability such as found with the application of exterior building louvres. 
         [0003]    Thermal isolation is especially important in today&#39;s environment. It has been found that, typically extruded metal, curtain wall mullions inevitably offer heat transfer paths from the interior of a building to the exterior. However, this energy transfer path has been exacerbated by the use of metal brackets which have traditionally been attached to the curtain wall mullion via screw-threaded fasteners which pierce the curtain wall mullion, thus providing a good heat transfer path. 
         [0004]    Presently, due to the complex and large nature of the bracket installation onto the exterior of a building, the curtain wall mullion is typically prepared off-site so as to be able to accept the specific bracket designated by the architect or designer. Following installation of the pre-prepared curtain wall mullion, the curtain wall bracket can thus be installed on-site. 
         [0005]    However, this is a time-consuming and more expensive route, whilst also making retro-fitting of brackets to existing curtain wall mullion particularly difficult. An existing building may require the brackets for the application of exterior solar shading and/or signage. To date, the exterior glass of the building which is attached and held by the curtain wall mullion typically has to be removed in order to affix the bracket. This in itself is often an enormous and expensive undertaking. Following this, a bracket which is adapted to be fastenable to the particular kind of curtain wall mullion already installed must then be selected and used, which may not be the preferred choice for the designer. 
         [0006]    Additionally, even when a bracket is attached to the curtain wall mullion, it is attached via screw-threaded fasteners which typically inevitably only engage along opposing sides of a bracket channel of the curtain wall mullion. This provides a weaker loading characteristic, since there is only a small portion of threaded engagement between the fasteners and the interior sides of the channel. Consequently, the intended loading which will be applied to the brackets must be very carefully considered and moderated. This again may not be the preferred option for a designer in terms of aesthetics, interior building temperature regulation, and also environmental issues. 
         [0007]    The present invention seeks to provide a solution to these problems. 
       SUMMARY OF THE INVENTION 
       [0008]    According to a first aspect of the invention, there is provided a method of attaching bracket apparatus to a curtain wall mullion having a fastening channel in which screw-threaded fasteners for a bracket element having upper and lower attachment ports are receivable, the method comprising the steps of: a) positioning the bracket element on the fastening channel so that a longitudinal opening of the channel is blocked along the longitudinal extent of the bracket element, and providing upper and lower blocking elements within the fastening channel so that the upper and lower attachment ports are in between the upper and lower blocking elements; and b) forcing an adhesive into one of the said upper and lower attachment ports until it appears in the other of the upper and lower attachment ports. 
         [0009]    According to a second aspect of the invention, there is provided curtain walling bracket apparatus comprising a bracket element having upper and lower attachment ports, blocking elements which block a fastening channel of a curtain wall mullion, and adhesive insertable into one of the upper and lower attachment ports. 
         [0010]    According to a third aspect of the invention, there is provided curtain wall mullion apparatus comprising a curtain wall mullion and curtain walling bracket apparatus in accordance with the second aspect of the invention, the bracket element being engaged with a fastening channel of the curtain wall mullion via said adhesive. 
         [0011]    The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a perspective view of one embodiment of curtain walling bracket apparatus, exploded relative to a curtain wall mullion and in accordance with the present invention; and 
           [0013]      FIG. 2  is a perspective view showing the installation of part of the curtain walling bracket apparatus to the curtain wall mullion, and in accordance with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Referring to the drawings, there is shown curtain wall mullion apparatus  10  which comprises a curtain wall mullion  12  and curtain walling bracket apparatus  14 . The curtain wall mullion  12  is elongate and typically formed from extruded metal, such as aluminium. The curtain wall mullion  12  has a rigid box-section tubular hollow body  16 , an integral fastening channel  18  which typically extends centrally along the entire longitudinal extent of exterior surface  20  of the hollow body  16 , and pane-mounting strips  22  which again are typically integrally formed as one-piece with the hollow body  16  at or adjacent to longitudinal perimeter edges of the exterior surface  20  of the hollow body  16 . 
         [0015]    The fastening channel  18  of the curtain wall mullion  12  has two parallel and spaced apart longitudinal side walls  24  and a bottom surface which interconnects the two side walls  24 . Each side wall  24  may have an in turned and/or out turned lip  26  at or adjacent to its distal free edge. The lip  26  is preferably continuously uniform and unbroken along the longitudinal extent of the curtain wall mullion  12 . The in turned lip  26  is beneficial for adhesive engagement and retention purposes as will be appreciated hereinafter, but also acts as seating for part of the curtain walling bracket apparatus  14  as will be understood below. 
         [0016]    Preferably, the interior side surfaces  28  of the fastening channel  18  are non-planar by incorporating striations or thread engagement grooves along the longitudinal extents thereof. 
         [0017]    The curtain walling bracket apparatus  14  comprises bracket element  30 , blocking elements  32 , and a, preferably resin, adhesive  34 . In this embodiment, the bracket element  30  includes a thermal break member  36 , an adaptor member  38 , and a bracket member  40 . 
         [0018]    The thermal break member  36  is formed of a thermally insulating material, such as plastics for example, nylon. The thermal break member  36  is elongate to preferably substantially match or exceed a base length of the adaptor member  38 , and is preferably thick enough so as to be rigid or substantially rigid. The thermal break member  36  also has a lateral extent which substantially matches or exceeds a lateral extent of the fastening channel  18 , so that it can be seated thereon as mentioned above. This enables the thermal break member  36  to extend in a lateral direction fully across a longitudinal opening to the fastening channel  18 , and in a longitudinal direction so as to cover at least a portion of the longitudinal opening. 
         [0019]    The thermal break member  36  may be formed with a protruding spine or other first locator  42  on or along the inwardly facing longitudinal surface which locates in the longitudinal opening  44  of the fastening channel  18 , thus aiding positioning. 
         [0020]    An adaptor channel or other second locator  46  may be provided on or along the outwardly facing longitudinal surface of the thermal break member  36  to aid positioning of the adaptor member  38 . 
         [0021]    The thermal break member  36  is provided with two blocking ports  48  at opposite end portions. The blocking ports  48  are apertures which extend through the body of the thermal break member  36  from the outwardly facing longitudinal surface  50  to the inwardly facing longitudinal surface  52 . The blocking ports  48  are dimensioned to receive the blocking elements  32  as a tight close fit. 
         [0022]    In between the blocking ports  48  are provided upper and lower attachment ports  54 ,  56  which, in this case, are close to the blocking ports  48 . 
         [0023]    In between the upper and lower attachment ports  54 ,  56  is a plurality of further attachment ports  58  provided in spaced relationship along the longitudinal extent of the body of the thermal break member  36 . 
         [0024]    The attachment ports  54 ,  56 ,  58 , like the blocking ports  48 , are apertures which extend through the body of the thermal break member  36  from the outwardly facing longitudinal surface  50  to the inwardly facing longitudinal surface  52 . 
         [0025]    To attach the thermal break member  36  to the fastening channel  18 , blocking elements  32  in the form of screw-threaded fasteners  60  are placed into the blocking ports  48  and screw-threadingly engaged with the interior side surfaces  28  of the fastening channel  18 . The threads of the blocking elements  32  engage with the striations on the interior side surfaces  28 , and preferably also cut further into the material of the side walls  24  of the fastening channel  18 . The blocking elements  32  also have a sufficient longitudinal extent so that they bottom out on the bottom surface of the fastening channel  18 . It is important that the blocking elements  32  are dimensioned to fully occlude or sufficiently block the fastening channel  18  whilst also engaging the thermal break member  36  so as to uniformly or substantially uniformly cover a corresponding portion of the opening  44  to the fastening channel  18 . 
         [0026]    The curtain walling bracket apparatus  14  further includes a plurality of plug elements  62 , which in this case are interconnected in spaced apart fashion to provide a plug strip  64 . Each plug element  62  is adapted for an interference fit in a respective one of the further attachment ports  58  in between the upper and lower attachment ports  54 ,  56 . 
         [0027]    With the plug strip  64  in place and blocking the further attachment ports  58 , an adhesive applicator  66  having a tapered nozzle  68  is utilised to force the resin adhesive  34  into the lower attachment port  56 . The tapering of the nozzle  68  provides a tight interference fit in the lower attachment port  56  to prevent or limit back flow there out. Due to the blocking elements  32  liquidly closing off the lower and upper portions of the fastening channel  18 , the adhesive  34  is forced along the fastening channel  18  until it reaches and flows into the upper attachment port  54 . Although the adhesive  34  can be inserted via the upper attachment port  54 , this will more likely leave voids in the blocked off portion of the fastening channel  18  which is not preferable. 
         [0028]    The plug strip  64  also prevents or limits leakage of the adhesive  34  from the further attachment ports  58 , as the adhesive  34  is being forced along the fastening channel  18 . 
         [0029]    Out flow through the channel opening  44  of the fastening channel  18  is also prevented or limited by the thermal break member  36  extending thereacross. 
         [0030]    Once the adhesive  34  is in place, the plug strip  64  can be removed. The adaptor member  38  can now be fastened to the thermal break member  36 . The adaptor member  38  is preferably a rigid elongate metal element adapted to provide engagement for the bracket element  30 . In this way, a specific adaptor member  38  can be utilised for providing an attachment interface for any specific bracket member  40 . This is far more cost-effective than having to remove the glass panes from the already installed curtain wall mullion  12 , or having to specify specific curtain wall mullions at the time of installation or construction in order to accommodate particular bracket members. 
         [0031]    In this embodiment, the adaptor member  38  has longitudinal and lateral extents which substantially match those of the thermal break member  36 . A bracket channel  70  is provided centrally longitudinally along an outermost surface  72  of the adaptor member  38 . Retainer apertures  74  are provided in spaced relationship along a bottom surface of the bracket channel  70 , and the retainer apertures  74  break out on an innermost surface  76  of the adaptor member  38 . The retainer apertures  74  align with the attachment ports  54 ,  56 ,  58  of the thermal break member  36 . 
         [0032]    The adaptor member  38  is engaged with the thermal break member  36  by screw-threaded adaptor fasteners  78  which extend through the retainer apertures  74  and the attachment ports  54 ,  56 ,  58  and which engage in the adhesive  34 . The blocking elements  32  may be initially removed either immediately if the adhesive is suitably viscous or once the adhesive is or starts to set. The adaptor fasteners  78  are preferably dimensioned so as to be slightly spaced from the interior side surfaces  28  of the fastening channel  18 , so that the threads are completely embedded within the adhesive  34 . This provides improved fixing strength and should not lead to bowing of the walls of the fastening channel  18 , which has to date been a problem with bracket fastening. However, additional direct engagement with the interior side surfaces  28  of course can be considered whereby a majority of the circumference of the threads is still engaged with the adhesive  34 . 
         [0033]    The adaptor fasteners  78  preferably do not penetrate into the interior of the hollow body  16  of the curtain wall mullion  12 . 
         [0034]    The cured adhesive  34  prevents or inhibits pullout of the adaptor fasteners  78  due to the striations and in turned lip  26  of the fastening channel  18 . 
         [0035]    To maintain thermal isolation, the adaptor fasteners  78  are located within thermal break sleeves  80 , and have a thermal break cap  82  provided on a head of each adaptor fastener  78 . The adhesive  34  also acts as a thermal isolator by encasing the typically metal adaptor fasteners  78  and keeping a separation between them and the curtain wall mullion  12 . The thermal break sleeves  80  and caps  82  are preferably of a thermally non-conductive material, such as plastics or rubber. 
         [0036]    The desired bracket member  40  can then be engaged in the bracket channel  70  of the adaptor member  38 , and fastened in place by bracket fasteners, such as screws, bolts, rivets or pins, which extend through lateral bracket ports  84  in the adaptor member  38  and the bracket member  40 . 
         [0037]    Following that, the required exterior solar shading louvres, signage and/or mounts can be connected to the or each bracket member  40 . 
         [0038]    Although the bracket apparatus described above comprises the thermal break member, adaptor member and bracket member, it is feasible that in some installations only the bracket member would be required. To this end, the bracket member may have upper and lower attachment ports for engagement via retainer fasteners with the fastening channel. Preferably, the bracket member would therefore also have the blocking ports for the blocking elements as described above, or the blocking elements could be separate of the bracket member. In this case, for example, the blocking elements could be further plugs which are adapted to block or occlude the fastening channel whilst not actually taking any bearing weight from the bracket apparatus. This would also be applicable to the thermal break embodiment described above, whereby the blocking ports actually forming part of the thermal break member could be dispensed with in favour of independent blocking elements. 
         [0039]    Additionally or alternatively, the thermal break member can be dispensed with in favour of just the adaptor member and bracket member. As above, the blocking ports can be provided on the adaptor member for the blocking elements, or the blocking elements can be provided separately. 
         [0040]    Although the bracket member is received in the adaptor member, it may sit on or straddle the adaptor member. 
         [0041]    The plug elements may not be required if the adhesive is being applied in the horizontal plane. However, if the adhesive is being applied with the curtain wall mullion in situ and typically being vertical, extrusion of adhesive out of the further attachment ports can be messy and thus the plug strip would be preferable. 
         [0042]    It is feasible that only one or no further attachment ports may be required, and thus only the upper and lower attachment ports are utilised. In this case, the plug strip can be dispensed with in favour of only one plug element or no plug elements. 
         [0043]    In the above described embodiments, it is of primary importance that the adhesive retains the retainer fasteners. It is not intended that the mating element with the fastening channel, such as the thermal break member, is actually bonded to the fastening channel, although this may occur. 
         [0044]    It is feasible that the mating element with the fastening channel, being the thermal break member, adaptor member or the bracket member, could include integrally formed blocking elements. 
         [0045]    The mating element may also include one or more protrusions, which may be integral and one-piece with the mating element, which project into the fastening channel for engagement with the adhesive. In this way, a bracket member could be connected to such a formed adapter member without the retainer fasteners projecting into the fastening channel. Alternatively, the retainer fasteners may be the aforementioned protrusion or protrusions whereby the bracket member can be directly bonded in the fastening channel without separate screw-threaded fasteners. In these cases, the upper and lower attachment ports are still provided for the application of the adhesive. 
         [0046]    It is thus possible to utilise an adhesive to improve the mounting of bracket apparatus to a curtain wall mullion, which in turn improves the load bearing capability of the bracket. It is also possible to provide an improved mounting method which utilises an adhesive to embed fasteners, thereby dispensing with the need for fasteners having an outside thread diameter which may cause deformation of the fastening channel. The use of blocking elements and plug elements prevents the application of adhesive being messy leading to undesirable running, and improves local application of the adhesive. The use of an adhesive also aids in improving thermal isolation and to provide a complete thermal break between a curtain wall mullion and a bracket element attached directly or indirectly thereto.