AU2014215989A1 - Chair for reinforcement - Google Patents

Abstract

Document15-21/08/2014 A chair for a reinforcing bar, the chair being a plastics moulding comprising an upper part with seating for the bar, and a set of outwardly splayed legs extending 5 downwardly from the upper part, wherein the upper part is stepped. 2-S% 2o2 q! J FIGUREk

Description

Document15-21/08/2014 CHAIR FOR REINFORCEMENT Field of the Invention 5 The present invention relates to a chair for supporting reinforcement for a cast concrete component and more particularly to a chair for a reinforcing bar within a grid or mesh of such bars. Background of the Invention 10 Concrete reinforcement in the form of a grid or mesh (hereinafter referred to simply as a "grid") is often used when constructing large flat concrete areas such as roadways, pathways, floors or concrete wall panels. The reinforcement is supported from the substrate on which the concrete is to be cast by chairs applied to individual bars within the 15 grid. Typically, the chair is in the form of a one-piece plastics moulding, and may have a clip to enable the chair to be applied to the grid before laying so that the chairs applied at appropriate positions throughout the grid will hang from the grid while the grid is being laid into position. With reinforcement in the form of a grid, it is inevitable that during setting up of the reinforcement prior to casting, workers will need to walk on the grid and 20 therefore it is necessary that the chairs have sufficient strength to carry the weight of persons standing on the grid, without the chairs breaking. While previous chairs have displayed sufficient strength, the applicant has identified that they use a relatively large amount of plastics material in their manufacture, 25 and this is of significance because the production cost of the chair is mainly dependent on the quantity of plastics material used in its manufacture. Examples of the invention seek to provide an improved chair for reinforcement which overcomes or at least alleviates disadvantages associated with existing chairs. 30 Documentl5-21/08/2014 -2 Summary of the Invention In accordance with the present invention, there is provided a chair for a reinforcing 5 bar, the chair being a plastics moulding comprising an upper part with seating for the bar, and a set of outwardly splayed legs extending downwardly from the upper part, wherein the upper part is stepped. Preferably, the upper part has at least one step defining a transition between an 10 outer portion of larger dimension and an inner portion of smaller dimension. More preferably, the outer portion is circular, the inner portion is circular, and the inner portion has a diameter smaller than a diameter of the outer portion. In one form, the step is an inward step such that the inner portion is above the outer portion. The step may be continuous around the upper part. 15 Preferably, the chair includes at least one pair of opposed seats for the bar. In a preferred form, the chair is a one-piece plastics moulding. 20 Preferably, the chair has a plurality of steps which progressively step the upper part inwardly toward a top of the chair. In one form, each step of the chair is above the splayed legs. 25 Preferably, the chair includes at least three legs. More preferably, the chair has four legs. Preferably, the legs are interconnected at their lower ends by a ring formed integrally as part of the chair. More preferably, the ring has a flat, planar underside, and 30 an upwardly extending circular outer flange.

Document15-21/08/2014 -3 In one form, each pair of adjacent legs is connected by an arch, and the arch has a central recess. It is preferred that the upper part of the chair includes two or more pairs of seats of 5 different depths to support the bar at different heights from a substrate on which the chair rests in use. Preferably, the chair is of open structure within its interior to enable a series of like chairs to be nested one inside another for transportation and storage. 10 Brief Description of the Drawings The invention is described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 15 Figure 1 is a perspective view of a chair for reinforcement in accordance with an example of the present invention; Figure 2 is a front view of the chair shown in Figure 1; 20 Figure 3 is a top view of the chair shown in Figure 1; Figure 4 is a bottom view of the chair shown in Figure 1; and 25 Figure 5 is a rear view of the chair shown in Figure 1. Detailed Description With reference to Figures 1 to 5, there is shown a chair 10 for reinforcement in 30 accordance with an example of the present invention. Advantageously, the chair 10 has an upper part which is stepped such that a crown of the chair is stiffened. This stiffening of the crown allows load applied to the top of the chair to be spread over all four legs of Document15-21/08/2014 -4 the chair, and not just the two legs where the load is applied, as has been the case with existing chairs. Spreading the load results in a far stronger chair, allowing less material to be used by thinning the walls and/or legs of the chair. In this way, the chair has a reduced weight, using less plastic material, yet still maintaining product load requirements. 5 Although the chair is shown as having two steps in the drawings, it will be appreciated that the chair may have one or more steps. Accordingly, this addresses a problem with existing chairs which has been identified by the applicant. In particular, the applicant has noticed that existing chairs 10 warp as they tend to direct most of the forces into the closest two legs, requiring stronger individual legs (and therefore more material) to resist the same loads. More specifically, Figures 1 to 5 show a chair 10 for a reinforcing bar, the chair 10 being a plastics moulding comprising an upper part 12 with seating 14 for the bar, and a 15 set of outwardly splayed legs 16 extending downwardly from the upper part 12. The upper part 12 is stepped. In particular, the upper part 12 has at least one step 18 defining a transition between an outer portion 20 of larger dimension and an inner portion 22 of smaller dimension. 20 The outer portion 20 is circular, the inner portion 22 is circular, and the inner portion 22 has a diameter smaller than the diameter of the outer portion 20. The step 18 is an inward step such that the inner portion 22 is above the outer portion 20. The step 18 is continuous around the upper part 12. 25 The upper part 12 also includes a second step 24 below the first step 18. As can be seen in the drawings, the first step 18 is above a level of ribs 26 of the legs 16, whereas the second step 24 intersects the ribs 26. The upper part 12 includes two pairs of opposed seats 28 for the bar. The 30 respective pairs of seats are offset by 900 about a vertical axis of the chair and are of different depths to permit the reinforcing bar to be located at one of two predetermined heights above the substrate on which the chair rests.

Document15-21/08/2014 -5 The chair is in the form of a one-piece plastics moulding, and the plurality of steps 18, 24 serve to progressively step the upper part 12 inwardly toward a top of the chair 10. In this way, the crown of the chair is stiffened for additional strength such that load is 5 distributed more evenly between all of the legs of the chair. In the example shown, the chair 10 has four legs 16 which are interconnected at their lower ends by a ring 30 formed integrally as part of the chair 10. The ring 30 has a flat, planar underside, and an upwardly extending outer flange 32. Each pair of adjacent 10 legs 16 is connected by an arch 34, and the arch 34 has a central recess 36. Advantageously, the recess allows for attaching tie-wire to the chair 10, and the flange 32 prevents tearing/damaging of the protection barrier between the slab and the ground. Advantageously, the chair 10 is of an open structure within its interior to enable a 15 series of like chairs to be nested one inside another for transportation and storage. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various 20 changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments. The reference in this specification to any prior publication (or information derived 25 from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. 30 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group Document15-21/08/2014 -6 of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (17)

1. A chair for a reinforcing bar, the chair being a plastics moulding comprising an upper part with seating for the bar, and a set of outwardly splayed legs extending 5 downwardly from the upper part, wherein the upper part is stepped.

2. A chair as claimed in claim 1, wherein the upper part has at least one step defining a transition between an outer portion of larger dimension and an inner portion of smaller dimension. 10

3. A chair as claimed in claim 2, wherein the outer portion is circular, the inner portion is circular, and the inner portion has a diameter smaller than a diameter of the outer portion. 15

4. A chair as claimed in claim 2 or claim 3, wherein the step is an inward step such that the inner portion is above the outer portion.

5. A chair as claimed in any one of claims 2 to 4, wherein the step is continuous around the upper part. 20

6. A chair as claimed in any one of claims 1 to 5, wherein the chair includes at least one pair of opposed seats for the bar.

7. A chair as claimed in any one of claims 1 to 6, wherein the chair is a one-piece 25 plastics moulding.

8. A chair as claimed in any one of claims 1 to 7, wherein the chair has a plurality of steps which progressively step the upper part inwardly toward a top of the chair. 30

9. A chair as claimed in any one of claims 1 to 8, wherein each step of the chair is above the splayed legs. Document15-21/08/2014

10. A chair as claimed in any one of claims 1 to 9, wherein the chair includes at least three legs.

11. A chair as claimed in claim 10, wherein the chair has four legs. 5

12. A chair as claimed in any one of claims 1 to 11, wherein the legs are interconnected at their lower ends by a ring formed integrally as part of the chair.

13. A chair as claimed in claim 12, wherein the ring has a flat, planar underside, and 10 an upwardly extending circular outer flange.

14. A chair as claimed in any one of claims 1 to 13, wherein each pair of adjacent legs is connected by an arch, and the arch has a central recess.

15 15. A chair as claimed in any one of claims 1 to 14, wherein the upper part of the chair includes two or more pairs of seats of different depths to support the bar at different heights from a substrate on which the chair rests in use.

16. A chair as claimed in any one of claims 1 to 15, wherein the chair is of open 20 structure within its interior to enable a series of like chairs to be nested one inside another for transportation and storage.

17. A chair substantially as hereinbefore described with reference to the accompanying drawings. 25