Abstract:
A unitary wire chair is disclosed for supporting concrete reinforcing rebar or the like above a supporting surface onto which concrete is poured. The unitary wire chair is so constructed such that it may be snapped or otherwise secured onto the rebar or other concrete reinforcing element and retained thereon without the use of any tie wire or other attachment devices.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to spacers, or so-called chairs, that are used in construction for the support of rebar, post-tension cables or wire mesh. More particularly, the present invention relates to chairs made of wire that are used for the support of rebar, post-tension cables, or wire mesh in poured concrete.  
       BACKGROUND OF THE INVENTION  
       [0002]     Spacers, or so-called chairs, are commonly used in the concrete construction industry for the support of rebar or post-tension cables or mesh above a surface onto which concrete is to be poured. Typically, rebar, cable or mesh, when used to reinforce concrete, must be supported above the surface onto which the concrete is poured. Chairs are generally used with poured concrete decks, pre-cast work, and bridges, roads or so-called slab-on-grade applications. In use, a rebar supporting surface on the chair supports the rebar while the base of the chair rests on the deck or surface to which the concrete is to be applied. When the concrete is poured, the chair maintains the cable or rebar a proper distance above the supporting surface.  
         [0003]     Currently, one of the most popular chairs used to support rebar is made from a pair of bent wires. A first bent wire is generally in the shape of an inverted U and has a recessed surface in the cross bar at the top onto which the rebar is located. The sides of the U-shaped wire support the recessed cross bar in an upright condition above the supporting surface. A second wire is formed as an inverted U and is welded to the bottom edge of the cross bar of the first wire and extends at 90° to that cross bar. The second wire also has vertically extending legs which support the second wire above the supporting surface. Generally, to prevent the rebar supported from this type of wire chair during pouring of the concrete, the rebar is tied to the supporting surface of the chair by a tie wire.  
         [0004]     One problem with this type of wire chair is that it is relatively expensive to manufacture because of the welding required in the course of its manufacture, but also because it requires substantial hand labor to manually attach the rebar to the chair by means of tie wires. It has therefore been an objective of this invention to provide a wire chair which is less costly to manufacture and which eliminates the need for tie wires to attach the wire chair to the rebar.  
         [0005]     There have been rebar supporting chairs manufactured which do not require the use of tie wires for attachment of the chair to the rebar. For example, as disclosed in U.S. Pat. No. 5,893,252, there are chairs which may be snap-fit onto the rebar so as to support that rebar above a supporting surface, but such snap-on-type of rebar supporting chairs have generally been made of plastic and are substantially more expensive and difficult to manufacture than wire rebar supporting chairs. It has therefore been another objective of this invention to provide a wire rebar supporting chair which may be snapped onto a rebar and frictionally held thereon without the need for tie wires or a complex plastic snap-fit connection.  
       SUMMARY OF THE INVENTION  
       [0006]     The wire rebar chairs of this invention are formed from a single unitary wire which supports a concrete reinforcing rebar or the like and which are so constructed that they may be snapped onto or otherwise secured onto the rebar or other concrete reinforcing element and retained thereon without the use of tie wires or other attachment devices. To that end, one embodiment of the invention comprises three parallel cross bars, a central one of which is adapted to be received atop a rebar and the other two parallel cross bars of which are adapted to be received on the underside of the rebar with connecting bars connected to opposite ends of the central one of the three parallel cross bars and riser bars extending downwardly away from the ends of each of the other two parallel cross bars, which riser bars terminate in a supporting foot. The supporting foot is intended to rest upon the supporting surface while concrete is poured onto that supporting surface. Preferably, this wire chair is heat-treated after formation of the chair so as to impart spring-like qualities to the wire chair, such that when secured onto a rebar, the spring-like qualities retain the wire chair on the rebar against any forces which it might otherwise tend to displace it.  
         [0007]     Another embodiment of the invention comprises a single unitary wire formed as two riser bars extending upwardly from opposite ends of a support foot section of wire. The two upwardly extending riser bars terminate in generally U-shaped loops which snap over and onto opposite sides of a rebar or like concrete reinforcing wire.  
         [0008]     In yet another embodiment of the invention, a single unitary wire has a straight upper horizontal bar section from the opposite ends of which are formed generally U-shaped loops which snap over a rebar or rebar-like concrete reinforcing wire. At the end of the loops opposite the straight horizontal bar section, riser bars extend generally downwardly to supporting foot sections of wire.  
         [0009]     As a still further modification of the embodiment described immediately hereinabove, the generally U-shaped loops are connected to a generally V-shaped nose section of the chair wire rather than a straight upper bar section of the unitary wire. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     These and other variations and embodiments of this invention will be more readily apparent from the following description of the drawings, in which:  
         [0011]      FIG. 1  is a perspective view of one embodiment of the wire chair of this invention supporting a rebar shown in phantom;  
         [0012]      FIG. 2  is a perspective view of multiple chairs supporting a rebar above a supporting surface;  
         [0013]      FIG. 3  is a side elevational view of the wire chair of  FIG. 1  supporting a rebar;  
         [0014]      FIG. 4  is a top plan view of the wire chair of  FIG. 1 , the rebar being shown in phantom;  
         [0015]      FIG. 5  is a perspective view illustrating how the wire chair of  FIGS. 1-4  is applied to the rebar;  
         [0016]      FIG. 6  is a perspective view of a modified form of chair incorporating the invention of this application; and  
         [0017]      FIGS. 7, 8  and  9  are perspective views of three further embodiments of the invention of this application. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     With reference first to  FIG. 1 , there is illustrated a concrete reinforcing element of rebar  10  and a rebar chair  12  made of one piece of wire  5  for supporting that rebar  10  a predetermined distance above a support surface  14  (see  FIG. 2 ). The chair  12  comprises three parallel cross bars  16 ,  18  and  20 , the centermost one,  18 , of which is connected to the other two  16  and  20  via connector bars  22  and  24 . As may be seen most clearly in  FIG. 3 , the centermost one of these three cross bars  18  is located atop the rebar  10  and the two other cross bars  16  and  18  are located on the underside of the rebar  10 . At its opposite ends, the centermost cross bar  18  is connected to the cross bars  16  and  20  by connector bars  22 ,  24  which extend downwardly and outwardly from opposite ends of the uppermost cross bar  18 . Ninety degree (90°) bends  26 ,  28  in the wire connect the opposite ends of the cross bar  18  to the connector bars  22  and  24 , respectively. See  FIG. 4 . Similarly, another ninety degree (90°) bend in the wire  5  connects each of the connecting bars  22 ,  24  to cross bars  16  and  20 , respectively. See  FIG. 4 .  
         [0019]     The ends of the outermost cross bars  16  and  20  opposite the end connected to the connector bars  22  and  24  is connected via ninety degree (90°) bends  34 ,  36 , respectively, to riser bars  40 ,  42 . The riser bars  40 ,  42  extend downwardly and outwardly away from the cross bars to which they are connected and terminate in supporting feet  44 ,  46 . Each supporting foot  44 ,  46  is connected to the lower end of the riser bars  40 ,  42 , respectively, by ninety degree (90°) bends  48  and  50 , in the wire, respectively. See  FIG. 4 .  
         [0020]     In the embodiment of the invention illustrated in  FIGS. 1-4 , each of the cross bars  16 ,  18  and  20 , as well as each connector bars  22  and  24 , and each riser bar  40 ,  42  is a linear straight bar connected to its next adjacent bar by a ninety degree (90°) bend in the wire  5 . So constructed, this embodiment of wire chair  12  may be easily formed on a conventional wire bending machine.  
         [0021]     As may be seen most clearly in  FIG. 3 , when the chair  12  is placed over a rebar  10  or other concrete reinforcing element, the cross bars  16 ,  18  and  20 , as well as the supporting feet  44  and  46  are all located in a horizontal plane with the supporting feet  44  and  46  intended to be resting upon the support surface  14  over which concrete is to be poured to encase the rebar or concrete reinforcing element in the concrete. In the embodiment here illustrated, the connecting bars  22  and  24  extend downwardly and outwardly from the horizontally extending cross bar  18  at an angle a approximately thirty degrees (30°) to a vertical plane  52  through the cross bar  18 . And in the preferred embodiment, the riser bars  40 ,  42  extend downwardly and outwardly from the horizontal cross bars  16  and  20  at an angle β at approximately thirty degrees (30°) to a vertical plane  54  through the cross bars  16  and  20 , respectively.  
         [0022]     In order to accommodate the chair to differing applications, the angles α and β may vary, as well as the length of the riser bars and connector bars. For example, if a smaller rebar or concrete reinforcing wire or element is utilized, the connector bars  22  and  24  will be shortened and/or the angle a increased to as to accommodate the smaller diameter rebar or wire. And similarly, if the rebar or concrete reinforcing element is to be increased in elevation relative to the supporting surface  14 , the length of the riser bars  40  and  42  would be increased and/or the angle β decreased to accomplish the increased elevation of the supported rebar or reinforcing element.  
         [0023]     In one preferred embodiment of this invention, after formation of the chair  12 , the chair is preferably subjected to a heat treatment so as to improve and increase the formed stability of the formed chair. One suitable heat treatment involves subjecting the formed chair to a temperature of 450 to 550° F. and then cooling the chair to room temperature so as to result in its having spring-like resilient qualities. Not only does this heat treatment increase the forms or shaped stability of the chair, but it better enables the chair to grip a rebar  10  inserted into the gaps  56 ,  58  between the cross bars  16 ,  18 ,  20  as explained more fully hereinafter.  
         [0024]     With reference now to  FIG. 5 , it will be seen that in order to attach a chair  12  to a rebar  10 , all that is required is for the chair  12  to be moved into a position relative to the rebar  10  in which the rebar is located within one of the pockets or gaps  56 ,  58 . Pocket  56  is defined between cross bars  18  and  20 . Pocket  58  is defined between cross bars  18  and  16 . See  FIG. 4 . Thereafter, the chair  12  may be rotated ninety degrees (90°) so as to position the rebar  10  within the other of the two pockets  56 ,  58 . See  FIG. 5 . When so positioned, the centermost cross bar  18  is located atop the rebar  10  and the other two cross bars  16  and  20  are located on the underside of the rebar  10 . Preferably, the connector bars  22  and  24  are of such a length and the angles a are such that in the course of rotating the chair ninety degrees (90°) so as to position the rebar  10  within the two pockets  56  and  58 , the cross bars  16  and  20  are forced outwardly away from the centermost cross bar  18  so as to securely lock the rebar  10  within these pockets  56 ,  58 .  
         [0025]     With reference now to  FIG. 6 , there is illustrated another embodiment of this invention. This embodiment of wire chair  12 ′ is identical to the embodiment of  FIGS. 1-5  except that the connector bars  22 ′ and  24 ′ are semicircular rather than straight bars. There are bending machines which will accommodate this configuration of wire bending without the need for ninety degree (90°) bends between the cross bars and connecting bars as in the embodiment of  FIGS. 1-5 .  
         [0026]     In the embodiment of  FIG. 6 , there may be detents (not shown) formed in the cross bars  18 ,  16  and  20 , respectively, so as to better enable the rebar  10  supported by the chair to be locked into the pockets  56 ,  58  of the chair. The detents will assist in preventing the chairs from being inadvertently knocked off of the rebar in the event that the force of the poured concrete contacting the chair tends to dislocate it, or in the event that workmen working in connection with the rebar step over or on it and tend to displace it.  
         [0027]     With reference now to  FIG. 7 , there is illustrated another embodiment of a wire chair incorporating the invention of this application. This chair  60  comprises a unitary wire, the center portion of which comprises a straight horizontal bar section  62  at the opposite ends of which there are formed generally U-shaped loops  64 ,  66  which are so sized as to be snapped over a rebar  68  or similar concrete reinforcing wire or rod. These loops  64 ,  66  terminate in a generally vertically extending riser bar  70 ,  72  at the end of each of which there is a horizontal extending supporting foot  74 ,  76 . These supporting feet,  74 ,  76 , support the chair  60  upon the surface to which concrete is to be applied after the rebar or concrete reinforcing wire or bar  68  is snap-fit into the loops  64 ,  66  of the chair  60 .  
         [0028]     With reference now to  FIG. 8 , there is illustrated yet another embodiment of a chair incorporating the invention of this application. This chair  80  is very similar to the chair  60  of  FIG. 7  except that instead of the generally horizontally extending straight bar  62 , the generally U-shaped loops  84 ,  86 , which are intended to be snap-fit over a rebar  68  or concrete reinforcing wire or rod, are connected to a generally V-shaped nose piece  82 . The opposite ends of this V-shaped nose piece  82  terminate in the loops  84 ,  86  within which the rebar  68  is received. The lower ends of these loops  84 ,  86  are connected to riser sections  88 ,  90  of the chair  80  which in turn are connected to supporting feet  92 ,  94 . In use, the feet  92 ,  94  rest upon the supporting surface to which concrete is to be applied while the chair supports the rebar or concrete reinforcing rod or wire above that supporting surface.  
         [0029]     With reference now to  FIG. 9 , there is illustrated yet another embodiment of a unitary wire chair incorporating the invention of this application. This chair  100  comprises a generally Z-shaped supporting foot  102  which forms the center portion of the wire chair. Riser bars  104 ,  106  extend upwardly from opposite ends of this Z-shaped generally supporting foot  102 . These riser bars  104 ,  106  terminate in generally U-shaped loops  108 ,  110  at the upper ends of the riser bars  104 ,  106 , respectively. In use of this chair  100 , the rebar  68  or concrete reinforcing rod wire  68  is inserted into the loops  108 ,  110 , one of which is located on one side of the rebar or rod, and the other of which is located on the opposite side. The rebar  68  is snap-fit into these loops  108 ,  110 , after which the rebar is firmly held by the chair  100  against movement or displacement of the chair  100  during pouring of the concrete.  
         [0030]     It will readily be apparent to persons skilled in the art that while we have described several embodiments of our invention, other changes and modifications may be made without departing from the spirit of our invention. Therefore, we do not intend it to be limited except by the scope of the following appended claims.