AU703307B2 - Bar chairs - Google Patents

Description

BAR CHAIRS The present in,:ention relates to bar chairs for supporting reinforcing bars or mesh for concrete in concrete slabs. It is particularly concerned with a modification or improvement to the bar chair described in our Patent Application AU-63369/94.

AU-63369/94 describes a bar chair having an integral base in which at le'st some of the disadvantages of the prior art described in that patent application are i' alleviated. That bar chair comprises: an upstanding body; an integral seat at an 15 upper end of the body for supporting part of a reinforcing bar or mesh which extends from one side to an opposite side of the bar chair; and an integral base at a lower end of the body, the bar chair being injection moulded in a mould having two parts which define, respectively, said one side and said opposite side of the bar chair and which meet when the mould is closed at a join line on the bar chair between the one side and the opposite side. It will be appreciated that the join line may not be visible in the finished bar chair.

By the invention of AU-63369/94 the bar chair can be readily injection moulded in a simple two-part mould. Since the two parts of the mould define respective sides, usually respective halves, of the bar chair, the mould cavity in each part has a depth which is not controlled by the height of the bar chair and each part of the mould can be relatively small compared to the height of the chair. This is of major advantage in that it substantially reduces the cost of the mould and therefore of the mouldings made therefrom, particularly for bar chairs over about 60 mm high and most especially for 100 mm+ bar chairs. It also makes it easier to manufacture thinner wall sections in the mould, allowing faster production times and lower manufacturing costs as well as lower packing and freight costs. That 951023,p:\oper\phhmodfix291,2 invention also allows for the provision of a seat in a single leg bar chair which has a greater cross-section than the upper end of the leg. This can spread the load of the reinforcing, giving greater strength to the bar chair, and increase the stability of the bar chair. Furthermore, such a mould can be readily modified to form a bar chair of increased height by providing inserts (which are fixed during injection moulding) for each of said mould parts which together define an extended length of the body, preferably of a substantially constant cross-section portion of the body.

The integral base provides stability to the bar chair, particularly to taller bar chairs.

The present invention concerns a modification or improvement to the invention of AU-63369/94 by which there is provided a bar chair for supporting reinforcing for concrete, comprising a single substantially solid leg, integral seat means at an upper end of the leg and an integral base at a lower end of the leg, the bar chair having been injection moulded in a mould having two parts which define, 15 respectively, one side and an opposite side of the bar chair and which meet when the mould is closed at a join line on the bar chair between the one side and the opposite side, wherein the integral seat means comprises two adjacent seats at different heights, each seat being adapted to support part of a reinforcing bar or mesh which extends from said one side to the opposite side of the bar chair.

The bar chair advantageously has a section which does not reduce from either said one side or said opposite side to the join line so that it can be formed without removable mould inserts.

The single leg is preferably of substantially constant cross-section along part of its length, most preferably a major part, but the cross-section may flare at a support portion which merges with the base. Further, the cross-section may reduce adjacent the integral seat means.

Preferably, the single leg is solid but it may have, for example, small material-saving openings therethrough from said one side to said opposite side.

951023,p:\oper\phhmadfi291,3 I I I b The single leg advantageously has a ribbed, thin wall cross-section with a main lateral wall extending along the join line, so as to maximise the strength of the bar chair with the minimum amount of material. The ribbed cross-section may include end ribs provided at lateral edges of the leg extending upwardly from the base and from said one side to said opposite side. Alternatively, or preferably in addition, a rib of the leg advantageously extends from said one side to said opposite side and upwardly from the base intermediatc the lateral edges of the leg to support the seat means. Preferably the seat means is located on top of the leg.

The two seats of the integral seat means are arranged at different heights so that the one bar chair may be used in either of two alternative occasions, when the reinforcing is to be at the smaller height or the greater height from the base of the concrete. Advantageously the two seats are arranged at least substantially to respective lateral sides of the leg, preferably laterally close to each other so as to be close to the centre of gravity of the bar chair. Most preferably the lower seat provides some support, directly or indirectly, for the upper seat. In a preferred embodiment the lower seat merges at its innermost side with the aforementioned intermediate rib of the leg to provide support for the lower seat and the intermediate rib may extend between the seats to provide support for the upper seat 20 if the lower seat does not directly provide support for the upper seat.

Each seat may comprise a linear groove of, for example, substantially U- or V-shape, and/or it may be arranged to clip onto the bar to positively locate it without necessarily gripping it. Such a clip-on seat may be upwardly open or may 25 include a resilient element which extends over the top of the seat so that the seat opens to the respective lateral side of the leg and may be essentially C-shaped. It is not essential, but preferred, that the resilient element or other arrangement which provides the clip-on engagement extends along the full length of the seat.

30 Each seat may readily have a greater length than the upper end of the leg from said one side to the opposite side across the cross-section of the leg, especially when the leg has a ribbed, thin-wall cross-section. Thus, the seat may, for example, S extend to said one and opposite sides to the same extent as the ribs adjacent the 951023,p:\opcr\phhniod ix.29 1, L M seat means. Each seat may also be supported by a buttress on said one and opposite sides to provide additional longitudinal support for the seat.

The bar chair may also readily include hooks or other features enabling the reinforcing bar to be tied down on the respective seat.

The base of the bar chair is preferably substa..ially flat but conveniently has a small taper, preferably a linear taper in its upper surface, to facilitate ejection from the mould, and/or a bevelled or rounded bottom edge. The base may have a circular or rectangular periphery, for example, but preferably is substantially Hshaped.

Two embodiments of a bar chair in accordance with the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a top perspective view of a first embodiment of the bar chair, and S'.also shows a possible modification; and Figure 2 is a top perspective view of a second embodiment of the bar chair.

Referring to Figure 1, the bar chair 10 comprises a ribbed, thin walled upright leg 12, an integral H-shaped base 14 at the bottom of the leg and an integral double seat arrangement 16 at the top of the leg. The bar chair 10 maybe integrally injection moulded in any suitable plastics material, such as, for example acrylonitrile-butadiene-styrene (ABS) graft terpolymers, polypropylene, high density polyethylene, polycarbonate and alloys thereof. It will be appreciated that the usual additives to such injection moulded plastics material, such as fillers, binders etc., may be incorporated.

The seat arrangement 16 comprises two seats 18 and 20 which will be described in detail hereinafter, but which are each arranged to support a reinforcing bar or rod (not shown) which extends longitudinally from one side of the bar chair to the other.

123,p: \oper\phhmocix29 II I I -6- The leg 12 is solid and comprises a thin wall 22 extending across the width of the leg in a vertical plane bisecting the length of the bar chair from said one side to the opposite side, opposed end ribs 24 and 26 extending longitudinally from the one side to the other side of the bar chair connected to the wall 22 at respective ends, and an intermediate rib 28 which extends parallel to a bottom portion of the ribs 24 and 26 and is equally spaced therefrom. All of the ribs 24, 26 and 28 extend longitudinally to an equal extent on both sides of the wail 22, but the end ribs 24 and 26 flare longitudinally outwardly in a support portion 30 adjacent the base to give the leg 12 longitudinal stability. The support portions 30 are integral with respective legs 32 of the H-shaped base 14, while the wall 22 bisects the cross-piece 34 of the base as well as extending partially into each leg 32 of the base.

o *Respective buttresses 36 extend between each leg 32 of the base 14 and the associated end rib 24 and 26 in the plane of the wall 22, to provide lateral stability to the leg 12. Each of the ribs 24, 26 and 28, the wall 22 and the buttresses have 15 approximately equal thicknesses.

In the embodiment illustrated in Figure 1, each seat 18 and 20 is designed for a relatively small diameter reinforcing rod or bar, for example upto 12 mm, and the upper end of the leg tapers upwardly and laterally inwardly to accommodate 20 this. Thus, an upper portion of each end rib 24 and 26 is inclined inwardly at 38 and 40 to merge with the respective seat 18 and 20. In an alternative embodiment, the lateral dimension of the leg 12 and base 14 may be reduced so that the end ribs 24 and 26 extend wholly vertically between the base and the respective seat, for example as shown in a different embodiment in Figure 2.

The two seats 18 and 20 are at different heights so that the bar chair may be used in two different circumstances, that is with the reinforcing intended to be at alternative heights. Each of the seats defines a linear substantially U-shaped groove 42 which extends longitudinally from the one side to the opposite side of the bar chair and is on a respective lateral side of the intermediate rib 28. Thus, each groove merges on its laterally inner side with the rib 28. Each seat is shown as of the clip-on variety so that an arcuate resilient element 44 extends from the rib 28 951023,p: \oper\phhmodfix.291,6 in a continuous arc with the respective gi oove 42 to define an essentially C-shaped seat. In order to facilitate entry of the reinforcing to the seat, the mouth 46 of each seat has flared lips 48 and 50. The lip 48 extends along the distal edge of the respective resilient element 44 while the lip 50 extends between the groove 42 of the respective seat and the respective inclined portion 38 or 40 of the associated end rib.

As a reinforcing bar or rod is urged into one of the seats 18 and 20 between the lips 48 and 50, the resilient element 44 will flex open to allow its passage and then resiliently close again to the condition shown in Figure 1. Unless the reinforcing rod or bar has a diameter the same as or larger than that of the arc defined by the groove 42 and resilient element 44 of the respective seat, the seat will not grip the rod or bar but will merely resist its withdrawal from the seat.

In order to reduce the force required to locate the reinforcing rod or bar in S. the respective seat, the length of the resilient element 44 and associated lip 48 may be shortened as shown in dashed lines in Figure 1.

Each seat 18 and 20 includes a buttress 64 between its lowermost portion and the wall 22 on each side of the wall in order to ensure the seat has adequate strength.

It may be seen that the section of the bar chair 10 does not reduce either from the one longitudinal side or the opposite longitudinal side to the lateral plane including the wall 22 and buttresses 36. This allows the bar chair to be injection moulded in a simple two-part mould which two parts close on that plane to define the join line. Any of the leg 12, base 14 and seat assembly 16 may taper slightly from the join line towards said one s.de and opposite side to facilitate ejection of the bar chair from the mould.

Moulding of a bar chair in such a mould is described in AU-63369/94, from which it will also be appreciated that the height of the bar chair 10 may be readily 951023,p:\Aper\phhmodfmx291,7

L~

8 increased by including fixed inserts in the mould, most easily within the portion which defines the parallel ribbed section of the leg 12 between the buttresses 36 and the inclined rib sections 38 and Referring now to Figure 2, it may be seen that this illustrates a very similar bar chair to that shown in Figure 1, with the major differences being in the upper part of the leg and the seat means. For this reason, only these features of Figure 2 will be described, although it may be pointed out that the various angles in the flared support portions 30 and buttresses 36 in Figure 1 are smoothed out in Figure 2. This modification is equally applicable to bar chair 10. For convenience, the same or similar parts to those in Figure 1 will be described by use of the same reference numeral as in Figure 1, followed by a The seat means 16' of the bar chair 10' shown in Figure 2 has two seats 18' 15 and 20' at different heights as in the bar chair 10, but these are intended for a t larger cross-section reinforcing bar or rod (not shown), for example up to 24 mm, and are not intended to clip-on to the reinforcing.

The end ribs 24' and 26' of the leg 12' extend vertically from the flared support portion 30' to the laterally outer and upper edges 52 and 54 of the upwardly open seats 18' and 20' respectively.

The seats 18' and 20' are defined by round-bottomed substantially V-shaped grooves 42' which extend linearly from the one longitudinal side to the other longitudinal side of the bar chair. As in Figure 1, the seat 18' is at a greater height than the seat 20' so that the rib 24' is taller than rib 26'. The laterally inner portion of the seat 18' is defined by a portion 56 of the groove 42' which projects upwardly over the seat 20' to the same height as the edge 52, above the intermediate rib 28'.

The upper end of the intermediate rib 28' merges with the groove 42' of the lower seat 20' at a junction 58 and the laterally inner portion 60 of the seat above the junction 58 provides support for the seat 18' at 6 2 951023,p:\oper\phhmodfiL29,8 LL- L LL1 -9- Reinforcing buttresses 64' are provided on each side of the central wall 22' between the wall and each seat 18' and 20'. In addition, a buttress 66 in the plane of the central wall 22' extends between the portion 56 of the seat 18' and the portion 60 of the seat 20', preferably substantially to the level of the junction 58.

Means as described in Application AU-63369/94 may be provided on the bar chair 10' for enabling reinforcing in either of the seats 18' and 20' to be tied down.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described.

It is to be understood that the invention includes all such variations and modifications which fall within its spirit and scope.

e s o ,g n, 951023,p: \oper\phhpmodfix.29 1,9

Claims (23)

1. A bar chair for supporting reinforcing for concrete, comprising a single substantially solid leg, integral seat means at an upper end of the leg and an integral base at a lower end of the leg, the bar chair having been injection moulded in a mould having two parts which define, respectively, one side and an opposite side of the bar chair and which meet when the mould is closed at a join line on the bar chair between the one side and the opposite side, wherein the integral seat means comprises two adjacent seats at different heights, each seat being adapted to support part of a reinforcing bar or mesh which extends from said one side to the opposite side of the bar chair.

2. A bar chair according to claim 1 which does not reduce in section from said one side to the join line and from said opposite side to the join line.

3. A bar chair according to claim 1 or claim 2 in which the leg has a ribbed, thin-wall cross-section, with a main lateral wall extending along the join line.

4. A bar chair according to claim 3 wherein a rib of the leg extends from said one side to opposite side and upwardly from the base intermediate the lateral edges of the leg to support the seat means.

A bar chair according to claim 4 wherein said intermediate rib extends upwardly from a lower of the two seats to the upper of the two seats.

6. A bar chair according to any one of claims 3 to 5 wherein end ribs are provided at lateral edges of the leg extending from said one side to said opposite side and upwardly from the base to the seat means.

7. A bar chair according to any one of claims 3 to 6 wherein the two seats extend longitudinally from the main lateral wall to both said one side and said opposite side. 951023,p:\oper\ phmodfix.291,10 LL I -11

8. A bar chair according to claim 7 wherein the rib or ribs have the same longitudinal extent as the seats adjacent the seat means.

9. A bar chair according to any one of claims 3 to 8 wherein the rib or ribs have a substantially constant longitudinal extent over at least a major part of the height of the leg.

A bar chair according to claim 6 or any claim dependent therefrom wherein the end ribs flare longitudinally adjacent the base.

11. A bar chair according to claim 3 or any claim dependent therefrom wherein the main lateral wall flares laterally adjacent the base.

12. A bar chair according to any one of the preceding claims wherein the two seats are arranged at least substantially to respective lateral sides of the leg.

13. A bar chair according to claim 12 wherein the two seats are laterally close to each other. S" 20

14. A bar chair according to claim 12 or claim 13 wherein a buttress extends from a lower of the seats to support the upper seat.

A bar chair according to any one of claims 12 or 14 wherein the seats are upwardly open.

16. A bar chair according to claim 15 wherein each seat is substantially U- or V-shaped.

17. A bar chair according to claim 15 wherein each seat is adapted to clip on to the reinforcing bar or mesh.

18. A bar chair according to any one of claims 12 to 14 wherein each seat is 951023,p:\oper\phh~modflx29 1,11 12- adapted to clip on to the reinforcing bar or mesh and includes a resilient element which extends over the top of the seat whereby the seat opens to its respective lateral side of' the leg.

19. A bar chair according to claim 18 wherein each resilient element extends the full length of the respective seat.

A bar chair according to claim 12 or any claim dependent therefrom when claim 12 is dependent from claim 7 wherein each seat is supported by a respective buttress projecting longitudinally from the main lateral wall on each of said one side and said opposite side.

21. A bar chair according to claim 6 or any claim dependent therefrom wherein the base is substantially H-shaped in plan view.

22. A bar chair according to any one of1 claims 1 to 21 wherein said support means is on top of said leg.

23. A bar chair substantially as hereinbefore described with reference to either Figure 1 or Figure 2 of the accompanying drawings. DATED this 19th day of January, 1999 MODFIX AUSTRALIA PTY. LTD. *0 DABy its Patent Attorneys DAVIES COLLISON CAVE 2 ll 25 MODFIX AUSTRALIA PTY. LTD. 99()12t).p: ,oper',phhilij ]iiH 291,12 I- -13- ABSTRACT A bar chair for supporting reinforcing for concrete, comprising a single substantially solid leg, integral seat means at an upper end of the leg and an integral base at a lower end of the leg, the bar chair having been injection moulded in a mould having two parts which define, respectively, one side and an opposite side of the bar chair and which meet when the mould is closed at a join line on the bar chair between the one side and the opposite side, wherein the integral seat means *comprises two adjacent seats at different heights, each seat being adapted to support part of a reinforcing bar or mesh which extends from said one side to the opposite side of the bar chair. *a 951023,p:\opr\phhmodfix.291,13 L I