Weldless Rebar Chairs

Abstract

A form for creating a weldless rebar chair has an elongate rod arranged along a predetermined direction, said rod being formed into at least a plurality of partial elongate loops spaced from each other along the predetermined direction and arranged in a common plane defined by the elongate rod and the elongate loops. A method of producing a weldless rebar chair comprising the steps of arranging an elongate rod along the predetermined direction and bending it to create the elongate loops spaced and bending the loops at transition points to form intermediate portions arranged in a common plane and free ends that extend in directions normal to the plane, alternate free ends being bent in opposite directions and having lengths that are substantially equal to provide legs that can be placed on a surface to stabilize the rebar chairs.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention generally relates to reinforcement bar supports in the construction trades and, more specifically, to weldless rebar chairs.

[0003] 2. Description of the Prior Art

[0004] Rebar spacers or chairs are devices that support and secure reinforcement steel bars or "rebars" in reinforced concrete structures as the rebars are assembled in place prior to the final pouring of the concrete. The spacers are left in place for the pour to keep them in place to become a permanent part of the structure.

[0005] Rebar spacers or chairs can generally be divided into three raw material categories: concrete spacers, plastic spacers and metal spacers. While plastic spacers generally have the advantage of being low cost and fast processing, plastic spacers or bar supports or "chairs" cannot bond well with concrete. They are not compatible materials. Also, plastic has a coefficient of thermal expansion and contraction that is approximately 10-15 times that of concrete. When subjected to temperature variations the plastic continues to expand and contract at that higher coefficient. Also, at high temperatures, plastic can even melt resulting in separation between the spacers and the poured concrete, creating free passages for corrosive elements to reach the steel reinforcements from the exterior of the concrete product. This frequently causes the steel, and eventually the concrete, to corrode. Concrete spacers are clearly made of the same material as the poured concrete, so thermal expansion and contraction are the same. Because they are the same material, the concrete spacers will bond with no gaps. Concrete spacers and bar supports help maintain the material integrity and uniformity of the concrete and provide a cover over the reinforcement that protects against corrosion. However, concrete spacers or chairs are impractical in some respects. They are heavy, tend to be brittle and crack prior to use and must be preformed for each size or height of chair required. Since chairs can be specified in increments of approximately one-half inch, this may result in a massive inventory problem that requires much space and expense. Many rebar spacers or chairs have been formed of steel. Examples of the different types of chair configurations are disclosed, for example, in a "Bar Support Handbook" published by Dayton Superior that lists the various types of metal, plastic and cementitious supports and their various properties. However, each of these categories must be formed in all the different sizes or heights that can be specified so all entail significant inventory problems.

[0006] While steel rebar chairs have proven to be very popular bar supports are frequently classified in terms of methods employed to minimize rust spots or similar blemishes on the surface of the concrete directly caused by the bar support. Thus, for example, one type of rebar chair is coated with plastic or is plastic protected. These provide protection intended for use in situations of moderate to severe exposure. Maximum protection is provided with epoxy-coated reinforcement bars. Bars that are vinyl-coated or plastic-coated are intended for use in situations of moderate to maximum exposure. They are generally used when epoxy-coated reinforcement bars are required. Steel and stainless steel chairs are used for moderate protection intended in situations of moderate exposure where the risk of rust needs to be taken into account. However, in a third category of chairs or spacers, no protection is provided against rusting. In selecting one of the chairs including plastic feet, epoxy coated or plastic tipped feet or stainless steel tips; the cost of production is always a factor.

[0007] Most of the steel chairs or spacers require some degree of welding to secure the chairs or rebar supporting members to the legs that are configured to provide the desired height(s) for positioning the supported rebars above the ground or other support surface. Despite the numerous finishes applied to steel spacers or supports a problem that has persisted is that many of the steel spacers or chairs typically rust within a matter of five to ten years. Therefore, there has existed a demand for a rebar chair or spacer that has a much longer lifetime without corroding. However, rebar steel that has resisted corrosion has also resisted being welded and, as indicated, steel spacers or chairs have traditionally required welding. These two desired properties have not been amenable to using corrosion-resistant steels such as the ChromX 9000 Series of steels marketed by MMFX Technology Corp. of Irvine, Calif.

SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of the invention to provide rebar spacers or chairs that do not have the disadvantages inherent prior art steel products of this type.

[0009] It is another object of the invention to provide rebars spacers or chairs that are simple in construction and economical to manufacture.

[0010] It is still another object of the invention to provide rebar spacers or chairs as in the previous objects that use ultra high strength corrosion-resistant steel that, at the same time, exhibits very good ductility and, therefore, can be bent into desired shapes.

[0011] It is yet another object of the invention to provide rebar spacers or chairs of the type under discussion that uses high strength corrosion resistant steel, despite being resistant to welding, that can be easily and inexpensively shaped to provide the desired spacer or chair configurations without welding.

[0012] It is a further object of the invention to provide rebar spacers or chairs as in the previous objects that can be formed on the fly as may be required in any given application to thereby avoid the need to stock large inventories of spacers or chairs in many incremental sizes or heights.

[0013] It is still a further object of the invention to provide rebar chairs or spacers as aforementioned that can use corrosion-resistant steel, such as the MMFX 9000 Series reinforcing steels that exhibit high strength and rebar corrosion resistance without the need for any welding to form spacers or chairs so that they are weldless and can be easily or readily customized to any given application.

[0014] It is yet a further object of the invention to provide rebar chairs or spacers that are weldless and can be formed by bending with inexpensive conventional steel rod bending machinery.

[0015] A weldless rebar chair can be produced by using an elongate rod of high strength, ductile and corrosion-resistant steel formed with elongate loops each provided with free ends and intermediate portions between the free ends and the elongate rod. The intermediate portions are arranged in a common plane defined by the elongate rod and the intermediate portions and the free ends are bent out of the common plane in directions generally normal to the intermediate portions. Alternate free ends are bent in opposite orthogonal directions in relation to the common plane. The intermediate portions of the loops have lengths within the common plane that are substantially equal to provide legs that can be placed on a surface to stabilize the rebar chair. The method of producing the aforementioned form and weldless rebar chair are also disclosed and form part of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Those skilled in the art will appreciate the improvements and advantages that derive from the present invention upon reading the following detailed description, claims, and drawings, in which:

[0017] FIG. 1 is a side elevational view of a form for creating a weldless rebar spacer or chair that includes a plurality spaced closed loops that project within a common plane in a direction away from the rod;

[0018] FIG. 2 is a side elevational view of a form for creating a weldless rebar spacer or chair that includes a plurality spaced open loops that project within a common plane in a direction away from the rod;

[0019] FIG. 3 is a side elevational view of a rebar spacer or chair formed from the form shown in FIG. 1;

[0020] FIG. 4 is a top plan view of the rebar spacer or chair shown in FIG. 3;

[0021] FIG. 5 is similar to FIG. 3 but showing a rebar spacer or chair made with the form shown in FIG. 2;

[0022] FIG. 6 is a top plan view of the rebar spacer or chair shown in FIG. 5;

[0023] FIG. 7 is a perspective view of three different spacers or chairs created from the open loop form shown in FIG. 2 wherein the intermediate portions are varied to change the heights of the rebar-supporting rods;

[0024] FIG. 8 is a perspective view showing two different height rebar spacers or chairs of the type shown in FIG. 7 for supporting reinforcing bars or rebars at two different heights or levels prior to pouring of concrete; and

[0025] FIG. 9 is a top plan view of the spacers or chairs and attached rebars as shown in FIG. 8.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0026] Referring now specifically to the Figures, in which identical or similar parts are designated by the same reference numerals throughout, and first referring to FIG. 1, a form for producing rebar spacers or chairs is designated by the reference numeral 10 comprises an elongate rod 12 that defines a predetermined direction, along axis A, the rod being formed with a plurality of at least partial elongate loops 14, generally uniformly spaced from each other as shown along the axis A. The rod 12 and the elongate loops 14 define a common plane (the plane of FIG. 1). The loops 14 in the form 10 are generally closed loops as shown. In the illustrated configuration the loops are spaced a distance S along the axis A. The widths of the individual loops 14 are designated by the dimension s although neither the dimensions S nor s is critical for the purposes of the present invention. These may be selected to meet specific requirements on a particular project, conform to required cost loads.

[0027] Further described in connection with FIGS. 3 and 4 the form 10 can be formed into rebar chairs or spacers by only using bending equipment. This requires that the bar or rod 12 is not only sufficiently strong to support the rebars but also must be ductile to allow bending or deformation of the steel to create the loops without undue effort or cost. This has been difficult if not impossible to do with stainless steel or other steels that are generally corrosion resistant. ChromX 9000 Series steels marketed by MMFX Technology Corp., of Irvine Calif. is an ideal material for use in connection with the rebar spacers or chairs in accordance with the invention. The use of ChromX 9000 Series steels, including 9100 (ASTM A1035 CS Grade 100 Steel) and 9120 (ASTM A1035 CS Grade 120 Steel) steels, with the subject invention save construction time and labor. The product's corrosion protection extends the service life and reduces the life cycle cost for concrete structures even in highly corrosive environments. Its uncoated corrosion protection means no additional costs from special handling, coating, inspection and repair. The aforementioned MMFX steels are more fully disclosed in U.S. Pat. No. 4,671,827 issued on Jun. 9, 1987 to Thomas et al., for Method of Forming High-Strength, Tough, Corrosion-Resistant Steel. Additional patents that have been issued relating to MMFX Steel that describes such corrosion resistance steel products include: U.S. Pat. Nos. 4,170,499; 4,619,714; 6,273,968; 6,709,534; 7,118,637; 6,746,548; 6,827,797; and 7,214,27.

[0028] The rod 12 can be bent by conventional machinery. The rods can be formed as shown in FIG. 1 either in predetermined or fixed lengths or be continuous. Referring to FIGS. 3 and 4, the advantages of the weldless method of creating rebar spacers or chairs will become immediately appreciated. The closed loops 14 shown in FIG. 1 have free ends 14a and intermediate portions 14b between the free ends 14a and the elongate steel rod 12. The intermediate portions 14b are arranged in a common plane, in the plane of the drawing, with the elongate rod 12 and the intermediate portion and the free ends 14a being bent out of the common plane in a direction generally normal to the intermediate portions. In order to form the spacers or chairs alternate free ends 14a are bent in opposite orthogonal directions in relation to the common plane. The intermediate portions 14b have lengths within the common plane which are substantially equal to provide legs 22 that can be placed on a surface to stabilize the rebar spacers or chairs.

[0029] The specific configurations of the loops that are formed from the rod 12 are not critical. What is important is that the loops extend from the rod along a direction A.sub.T so that the loops can define a transition point 14c that separates the free ends 14a and the intermediate portions 14b. In FIGS. 1, 3 and 4 the loops are shown to be closed loops. In FIGS. 2, 5 and 6 the loops are shown as open loops 16. Either one can be used with different degrees of advantage. In both configurations, the loops extend along a transverse direction A.sub.T to the axis A and have a total length L. The free ends have a length m while the intermediate portions have a length equal to 1 so that L=l+m. In forming a spacer or chair from either one of the forms shown in FIGS. 1 and 2, the loops 14, 16 are bent at the transition points 14c, 16c respectively to form intermediate portions 14b, 16b arranged in the common plane defined by the elongate rods 12 and the intermediate portions while the free ends 14a, 16a respectively extend out of the common plane in directions generally normal to the intermediate portions as shown. Alternate free ends are bent in opposite orthogonal directions in relation to the common plane so that the intermediate portions have substantially equal lengths l within the common plane to provide similarly dimensioned legs 22 that can be placed on a surface to stabilize the rebar space or chair.

[0030] Referring to FIG. 7, three different configurations 20, 20', 20'' of the open loop rebar spacer or chair of the type shown in FIGS. 2, 5 and 6 are shown. Each of these was initially formed from the same open loop form 10' each having loops with the same longitudinal length L. The spacer or chair 20 was formed by bending the open loop 16 to provide an intermediate portion 16b that generally raises the height of the rod 12 above the support surface at the same time generally decreasing the length of the free end 16a. The intermediate spacer or chair 20' shown in FIG. 7 is formed to lower the height of the rod 12 by decreasing the height of the intermediate portion 16b', thereby increasing the length of the free end 16a'. As indicated, the total lengths the free ends and the intermediate portions will be equal to the initial overall length L of the loops. Similarly, the spacer or chair 20'' is similar to the other chairs 20, 20' except that now the rod 12 has been lowered still further by decreasing the dimension of 16b'' while, as before, the length of the free end 16a'' increases. Clearly, the lengths of the free ends 16a, 16a' and 16a'' is not critical and can be any dimension. The only critical dimension is the heights of the intermediate portions which can be customized to accommodate any given height requirement without considering the otherwise needed dimensions or heights. Referring to FIGS. 8 and 9, there is illustrated the means for supporting two levels of reinforcement bars or rebars at two different heights, using the lowest height spacer or chair 20 shown in FIG. 7 and the higher height spacer or chair 20''. The lower rebars are designated by the reference numeral 24 while the higher rebars are designated by the reference numeral 26. Transverse rebars 28 can also be secured to the rebars 24, 26 that rest directly on the spacers or chairs. Conventional ties 30 can be used to secure the rebars to each other or rebars to the chairs or spacers as shown.

[0031] It will be appreciated that the present invention provides tremendous flexibility in the construction trades. Not only is the product superior and can last over a hundred years without corrosion the inventory problem is virtually eliminated or significantly reduced. Whether the loops are closed, open or otherwise a steel of the type under discussion that can be readily bent to provide the desired heights of the spacers or chairs can be made in whatever heights are needed from the same forms by making the dimension L sufficiently large to allow the formation of rebar spacers or chairs with legs determined by the desired or required dimension l. These can provide the full gamut of heights that may be needed at a construction site.

[0032] While the presently preferred embodiments utilize MMFX steels as aforementioned, other steels that have similar properties can also be used, namely high strength, good ductility and corrosion resistant steels. Preferably, the steel should be corrosion resistant for at least one hundred years. Thus, while the initial cost of both the steel and production might be higher than the use of conventional steels such higher initial cost is offset by the extended corrosion resistance so that over the long term the effective costs of installation, construction and repair will be reduced.

[0033] The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

1. A form for creating a weld-less rebar chair comprising a continuous elongate rod arranged along a predetermined direction, said rod being formed into at least a plurality of loops extending substantially equal distances in a common direction normal to said predetermined direction spaced from each other along said predetermined direction and arranged in a common plane defined by said elongate rod and said elongate loops.

2. A form as defined in claim 1, wherein said loops are elongate loops.

3. A form as defined in claim 1, wherein said loops are open loops.

4. A form as defined in claim 1, wherein said loops are closed loops.

5. A form as defined in claim 1, wherein said elongate rod is made of ASTM A1035 CS Grade 100 steel.

6. A form as defined in claim 1, wherein said elongate rod is made of ASTM A1035 CS Grade 120 steel.

7. A form as defined in claim 1, wherein said elongate rod is made of steel that achieves yield strength between 100 and 120 Ksi of the ASTM A1035 specification while maintaining ductility and tensile-to-yield ratio above 1.25.

8. A weld-less rebar chair comprising an elongate rod arranged along a predetermined direction, said rod being formed into at least a plurality of loops extending substantially equal distances in a common direction normal to said predetermined direction spaced from each other along said predetermined direction, said loops having free ends and intermediate portions between said free ends and said elongate rod, said intermediate portions being arranged in a common plane defined by said elongate rod and said intermediate portions and said free ends being bent out of said common plane in directions generally normal to said intermediate portions, alternate free ends being bent in opposite orthogonal directions in relation to said common plane, said intermediate portions having lengths within said common plane that are substantially equal to provide legs that can be placed on a surface to stabilize the rebar chair.

9. A weld-less rebar chair as defined in claim 8, wherein said loops are elongate loops.

10. A weld-less rebar chair as defined in claim 8, wherein said loops are open loops.

11. A weld-less rebar chair as defined in claim 8, wherein said loops are closed loops.

12. A weld-less rebar chair as defined in claim 8, wherein said elongate rod is made of ASTM A1035 CS Grade 100 steel.

13. A weld-less rebar chair as defined in claim 8, wherein said elongate rod is made of ASTM A1035 CS Grade 120 steel.

14. A weld-less rebar chair as defined in claim 8, wherein said elongate rod is made of steel that achieves yield strength between 100 and 120 Ksi of the ASTM A1035 specification while maintaining ductility and tensile-to-yield ratio above 1.25.

15. A method of producing a form for creating a weld-less rebar chair comprising the steps of selecting a length of an elongate continuous rod and arranging it along a predetermined direction; bending said rod to create a plurality of loops extending substantially equal distances in a common direction normal to said predetermined direction spaced from each other along said predetermined direction in a common plane defined by said elongate rod and said elongate loops.

16. A method as defined in claim 15, wherein said loops are open loops.

17. A method as defined in claim 15, wherein said loops are closed loops.

18. A method as defined in claim 15, wherein said elongate rod is made of ASTM A1035 CS Grade 100 steel.

19. A method as defined in claim 15, wherein said elongate rod is made of ASTM A1035 CS Grade 120 steel.

20. A method as defined in claim 15, wherein said elongate rod is made of steel that achieves yield strength between 100 and 120 Ksi of the ASTM A1035 specification while maintaining ductility and tensile-to-yield ratio above 1.25.

21. A method of producing a weld-less rebar chair comprising the steps of selecting a length of an elongate continuous rod and arranging it along a predetermined direction; bending said rod to create at least a plurality of loops extending substantially equal distances in a common direction normal to said predetermined direction spaced from each other along said predetermined direction, bending said loops at transition points to form intermediate portions arranged in a common plane defined by said elongate rod and said intermediate portions and free ends that extend out of said common plane in directions generally normal to said intermediate portions, alternate free ends being bent in opposite orthogonal directions in relation to said common plane, said intermediate portions having lengths within said common plane that are substantially equal to provide legs that can be placed on a surface to stabilize the rebar chairs.