Patent Publication Number: US-2009235601-A1

Title: Wall unit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application related to and claims priority to Irish Patent Application Serial Number S2008/0203, filed Mar. 19, 2008, Irish Patent Application Serial Number S2008/0204, filed Mar. 19, 2008, Irish Patent Application Serial Number S2008/0205, filed Mar. 19, 2008, and Irish Patent Application Serial Number S2008/716, filed Sep. 3, 2008, the entirety of all which are incorporated herein by reference. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     n/a 
     FIELD OF INVENTION 
     The present invention relates to wall units such as, but not limited to prefabricated wall units. 
     BACKGROUND OF THE INVENTION 
     A type of wall construction is known in which formwork panels are mounted vertically upright and parallel to one another on a solid concrete floor, and the gap between the two filled with concrete. When the concrete is set the formwork panels may be removed, or left in place to form an integral part of the wall. In the later case they are known as permanent formwork panels and are typically made of cement—see, for example, WO 2004/091903. 
     It is therefore desirable to provide an improved wall unit for use in this type of construction, as well as a method of manufacturing such a wall unit and a wall tie for use in the construction of such a unit. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a wall unit comprising a set of substantially parallel elongated wall ties having opposite edges which are substantially coplanar on each side of the set so as to lie in two substantially parallel planes containing said edges, at least one reinforcing mesh recessed into the wall ties on at least one side of the set by being received in slots in the wall tie edges on that side of the set, and at least one formwork panel secured to the substantially coplanar edges on each side of the set of wall ties. 
     The invention further provides a method of manufacturing a wall unit comprising assembling a set of substantially parallel elongated wall ties having opposite edges which are substantially coplanar on each side of the set so as to lie in two substantially parallel planes containing said edges, recessing at least one reinforcing mesh into the wall ties on at least one side of the set by inserting the mesh in slots in the wall tie edges on that side of the set, and securing at least one formwork panel to the substantially coplanar edges on each side of the set of wall ties. 
     The invention further provides a wall tie for spacing opposite substantially parallel formwork panels in a wall unit, the wall tie comprising an elongated member with substantially parallel opposite flat longitudinal edges for retaining a formwork panel, each edge having a plurality of slots which intermittently interrupt the edge to allow a reinforcing mesh to be recessed into the wall tie clear of the edge. 
     The invention also provides a wall unit made by the above method. According to a further aspect of the present invention there is provided a method of manufacturing a wall unit comprising assembling a set of substantially parallel vertical elongated wall ties having opposite edges which are substantially coplanar on each side of the set, each wall tie having a plurality of openings distributed along its length between its opposite edges with the openings of adjacent wall ties substantially aligned in a horizontal direction, inserting a plurality of reinforcing rods horizontally through respective sets of aligned openings, the openings being configured such that under gravity each rod is deflected towards, and comes to rest adjacent, an edge of the wall tie, and securing at least one formwork panel to the substantially coplanar edges on each side of the set of wall ties. 
     The invention also provides a wall unit made by the above method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
       An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows on the left hand side, a side view and on the right hand side a perspective view of a wall tie used in the construction of a wall unit ( FIG. 8 ) according to a first embodiment of the invention. 
         FIG. 1   a  is a horizontal cross-section through the set of vertical wall ties shown in  FIG. 2  which is used as the starting point in the manufacture of the wall unit of  FIG. 8 . 
         FIGS. 2 to 7  are perspective views of the wall unit of  FIG. 8  in successive stages of manufacture. 
         FIG. 2   a  is a cross-section of the apparatus of  FIG. 1  prior to the engagement of the support rails with the spacer. 
         FIG. 8  shows the resulting wall unit according to the first embodiment of the invention. 
         FIG. 9  is a schematic plan view illustrating a T-shaped join between wall units 
         FIG. 10  is a perspective view of a wall tie used in a second embodiment of the invention. 
         FIGS. 11(   a ) to  11 ( d ) are vertical cross-sections through the wall unit according to the second embodiment of the invention at various stages of its construction. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the drawings the same reference numerals have been used for the same or equivalent components in the various embodiments. 
     Referring to  FIG. 1 , a wall tie  10  used in the construction of the wall unit of  FIG. 8  comprises an elongated member  12  having a generally I-shaped cross-section with substantially parallel opposite flat longitudinal edges  14 . The member can be formed from metal including steel or aluminum or from a polymer, for example, PVC or composite material according to the engineering requirements for the wall unit. Each edge  14  has a plurality of slots  16  which intermittently interrupt the edge at regular intervals to allow a reinforcing mesh to be recessed into the wall tie clear of the edge  14 , as will be described. The wall tie  10  also has a plurality of openings  18  distributed along its length between the opposite edges  14 , and a short tab  20  at each end allows the lower end of the wall tie, when assembled into a wall unit with like ties as will be described, to locate between a pair of parallel floor-mounted support rails of the kind described in U.S. application Ser. No. 12/366,157, the disclosure of which is herein incorporated by reference. 
     Referring now to  FIGS. 1   a  and  2 , the first stage in manufacturing the wall unit is to assemble a set of substantially vertical wall ties  10  side-by-side and substantially parallel to one another. Preferably, the ties are loaded into a floor mounted magazine and thereafter held in place in the temporary state by a jig (not shown) from which they depend in spaced apart relationship. The wall ties  10  have their opposite edges  14  substantially coplanar on each side of the set of wall ties so that all the edges  14  on one side of the set lie substantially in a first plane P 1  ( FIG. 1   a ) and all the edges  14  on the other side of the set lie substantially in a second plane P 2 , the planes P 1 , P 2  being substantially parallel to one another. Also, the openings  18  in adjacent wall ties are horizontally aligned. 
     Next,  FIG. 3 , vertical steel reinforcing rods  22  are inserted between adjacent wall ties  10  so as to extend substantially parallel to the wall ties along the opposite vertical edges of a rectangular window opening  24  ( FIG. 8 ) subsequently formed in the set of wall ties. The rods  22  are secured to the wall ties  10  by twisted wire. 
     Then,  FIGS. 3 and 4 , a respective rectangular steel mesh  26  having a vertical pitch the same as the spacing of the slots  16  and a horizontal pitch the same as the spacing of the wall ties  10 , is set into the slots  16  on each side of the set of wall ties (only one mesh is shown in  FIG. 3 ). In particular, each horizontal rod  28  of the mesh  26  enters a respective set of horizontally aligned slots  16 , while each vertical rod  30  enters the gap between a pair of adjacent wall ties  10 . Thus each mesh is recessed into the wall ties  10  behind, i.e. clear of, the opposite flat edges  14 . 
     Next,  FIG. 4 , horizontal steel reinforcing rods  32  are inserted through the aligned openings  18  so as to extend along opposite horizontal edges of the rectangular window opening  24  ( FIG. 8 ) subsequently to be formed. The rods  32  are secured to the wall ties  10  and/or to the mesh  26  by twisted wire. At his point the vertical steel reinforcing rods  22  can also be secured to the mesh. 
     Now,  FIG. 5 , each side of the wall tie assembly is covered with edge-to-edge abutting cement formwork panels  34  which are adhesively and/or mechanically secured to the substantially coplanar wall tie edges  14  on each side of the set of wall ties. Preferably, a polyurethane based adhesive may be used, although any suitable fixing mechanism can be employed including screws. In the case where a rectangular opening is to be formed in the finished wall unit, the panels  34  are pre-cut to define the periphery of the opening, as indicated at  36 . Next, pull-out bars  38  are slid into each end of the assembly. Each bar  38  has a pair of legs  40  which are slidably inserted into horizontally aligned slots  18  alongside respective horizontal mesh rods  28 . The bars  38  may be pulled out to any desired extend from the end of the wall tie assembly, for a purpose to be explained. 
     Now the rectangular section  42  of wall ties  10  and mesh  26  revealed in the panel opening  36  is cut out,  FIG. 6 , to form the window opening  24 . A reveal  44  is now inserted into the opening  24  to close off the gap between the cut edges of the panels  34 ,  FIGS. 7 and 8 . 
     At this point the wall unit is complete except for its concrete filling, and is preferably pre-fabricated off-site and transported as a self-supporting unit to the construction site. 
     At the construction site the unit is located on a pair of parallel floor-mounted support rails of the kind described in the above U.S. patent application Ser. No. 12/366,157, the short tabs  20  at the bottom edge of the unit locating between the rails. When the unit is in its final position, a concrete filling is poured into the gap between the formwork panels  34  and allowed to set. To avoid the concrete escaping, the vertical gap between the panels  34  at the ends of the unit are closed off either by the unit abutting edge-to-edge against another such unit, with the gap between the two being permanently bridged by further cement board permanent formwork, or by the unit joining another wall at a T shaped junction, for example as shown in  FIG. 9 . 
     In  FIG. 9  three wall units  50   a,    50   b  and  50   c  are shown meeting at a T-junction, prior to pouring the concrete filling. The units  50   a  and  50   c  are in-line and the vertical gap between their panels  34  are closed on one side by a permanent formwork panel  52 , and on the other side by the unit  50   b.  The three units are coupled by their pull-out bars  38  which are wired together and become embedded in the concrete to reinforce the T-join. 
     Barcodes (or other machine-readable identifiers) are applied to the pre-fabricated wall units as they are produced and the units are shipped with their associated support rails and formwork panels  52  which are also bar-coded. 
     When a rail is scanned on site with a handheld scanner attached to a PDA on which a model of the building is either stored or accessible across a network, the PDA can display where the rail is to be fixed on the ground. Similarly, before being placed in position, the wall unit and formwork panels  52  can be scanned to ensure they are properly located and also to update the progress of the construction through the PDA. 
     The number of parallel side-by-side wall ties  10  in a particular wall unit, as well as their length and the distance between their opposite edges, may be varied according to the required dimensions of the wall unit. 
     A second embodiment of the invention will now be described with reference to  FIGS. 10 and 11  ( FIG. 11   d  is an enlarged view of part of the final structure shown in  FIG. 11   c ). 
     Referring to  FIG. 10 , a wall tie  100  used in the second embodiment comprises an elongated member  112  having a generally I-shaped cross-section with substantially parallel opposite flat longitudinal edges  114 . The member can be formed from metal including steel or aluminum or from a polymer, for example, PVC or composite material according to the engineering requirements for the wall unit. Struts  116  extending between the opposite edges  114  define a plurality of triangular openings  118  distributed along the length of the wall tie between the opposite edges  114 . A short tab (not shown) at each end allows the lower end of the wall tie, when assembled into a wall unit with like ties as will be described, to locate between a pair of parallel floor-mounted support rails of the kind described in U.S. patent application Ser. No. 12/366,157, which is incorporated herein by reference. 
     The first stage in manufacturing the wall unit is to assemble a set of substantially vertical wall ties  110  side-by-side and substantially parallel to one another, in the manner shown in  FIG. 2  for the prior assembly. Preferably, the ties are loaded into a floor mounted magazine and thereafter held in place in the temporary state by a jig (not shown) from which they depend in spaced apart relationship. The wall ties  110  have their opposite edges  14  substantially coplanar on each side of the set of wall ties so that all the edges  14  on one side of the set lie substantially in a first plane P 1  ( FIG. 11   a ) and all the edges  14  on the other side of the set lie substantially in a second plane P 2 , the planes P 1 , P 2  being substantially parallel to one another. Also, the triangular openings  118  in adjacent wall ties are horizontally aligned. 
     Next,  FIG. 11   b,  steel reinforcing rods  132  are inserted horizontally through respective sets of aligned triangular openings  118 —in particular, the rods are inserted through sets whose triangular openings, such as those indicated at  118   a,  have a downwardly pointing lowermost angle adjacent an edge  114  of the wall tie. Therefore, when released, each rod  132  is deflected under gravity towards, and comes to rest adjacent to, an edge  114 . As shown, vertically consecutive rods  132  come to rest adjacent alternate edges of the wall ties. The rods  132  are secured to the wall ties  110  by twisted wire 
     Next, vertical steel reinforcing rods (not shown) are inserted between adjacent wall ties  110  so as to extend substantially parallel to the wall ties, and are secured by twisted wire. 
     Now,  FIGS. 11   c  and  11   d,  each side of the wall tie assembly is covered with edge-to-edge abutting cement formwork panels  134  which are adhesively and/or mechanically secured to the substantially coplanar wall tie edges  114  on each side of the set of wall ties. Preferably, a polyurethane based adhesive may be used, although any suitable fixing mechanism can be employed including screws. In the case where a rectangular door or window opening is to be formed in the finished wall unit, the panels  134  are pre-cut to define the periphery of the opening in the manner previously described, and the horizontal and vertical reinforcing rods are positioned to avoid the location of the opening. As before, a reveal (not shown) is inserted into the opening to close off the gap between the cut edges of the panels  134 . Pull-out bars (not shown) but similar to the bars  38  may be fitted. 
     At this point the wall unit is complete except for its concrete filling, and is preferably pre-fabricated off-site and transported as a self-supporting unit to the construction site. 
     At the construction site the unit is located on a pair of parallel floor-mounted support rails of the kind described in the above U.S. patent application Ser. No. 12/366,157, the short tabs at the bottom edge of the unit locating between the rails. When the unit is in its final position, a concrete filling is poured into the gap between the formwork panels  134  and allowed to set. To avoid the concrete escaping, the vertical gap between the panels  134  at the ends of the unit are closed off either by the unit abutting edge-to-edge against another such unit, with the gap between the two being permanently bridged by further cement board permanent formwork, or by the unit joining another wall at a T shaped junction. 
     Barcodes (or other machine-readable identifiers) are applied to the pre-fabricated wall units as they are produced and the units are shipped with their associated support rails and bridging formwork panels which are also bar-coded. 
     When a rail is scanned on site with a handheld scanner attached to a PDA on which a model of the building is either stored or accessible across a network, the PDA can display where the rail is to be fixed on the ground. Similarly before being placed in position, the wall unit and bridging formwork panels can be scanned to ensure they are properly located and also to update the progress of the construction through the PDA. 
     The number of parallel side-by-side wall ties  110  in a particular wall unit, as well as their length and the distance between their opposite edges, may be varied according to the required dimensions of the wall unit. 
     The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.