AU2015205907B1

AU2015205907B1 - Supporting Chair For Hob Mould And The Like

Info

Publication number: AU2015205907B1
Application number: AU2015205907A
Authority: AU
Inventors: Antonio Pantano
Original assignee: Masterform Systems Pty Ltd
Current assignee: Masterform Systems Pty Ltd
Priority date: 2014-08-12
Filing date: 2015-07-17
Publication date: 2016-07-07
Anticipated expiration: 2034-08-12
Also published as: AU2014213545B1; AU2016200499A1

Abstract

A chair to temporarily support from formwork elements to be embedded in reinforced concrete structures, said chair comprising a baseplate or other parts homologous with said baseplate, a threaded bore passing 5 centrally and vertically through said baseplate or said homologous parts, said baseplate or said homologous parts being supported above said formwork on three or more splayed, equally-spaced legs, a column in the form of a stiff threaded rod screwably engaged with said threaded bore, said legs being fixable to said formwork and the height of said supported 10 elements above said formwork being adjustable by screwably displacing said column in an appropriate sense in said threaded bore.

Description

SUPPORTING CHAIR FOR HOB MOULD AND THE LIKE

This invention relates generally to means to temporarily support materials and apparatus employed in the building construction process. More particularly, it relates to means to temporarily support moulds for the creation of sills or hobs on cast-in-situ concrete building slabs, secondary formwork for the creation of step level changes and localised level changes in such concrete slabs, steel reinforcing bar for the reinforcement of such concrete slabs, or cast-in anchors and other building elements to be embedded in such concrete slabs; excepting some forms of said secondary formwork, all such apparatus remaining embedded in such concrete slabs following their pouring and curing.

Particularly in the construction of multi-storey, reinforced-concrete buildings, it is common to provide raised sills or hobs of some form to cast-in-situ concrete slabs. Sills or hobs are raised linear features which act as supports for building elements, such as window frames, curtain wall panels and the like. Similarly, step level changes are commonly incorporated into such concrete slabs, as are a wide variety of arrangements of steel reinforcing bar. In the most efficient process, the creation of sills or hobs on a concrete building slab requires the provision of a specially fabricated mould, supported on a plurality of chairs at an appropriate height above formwork for the making of said slab. The mould and chairs are set in place during the process of installing steel reinforcing bar in the formwork and the mould is filled with concrete during pouring of the concrete slab. Step level changes are created in a concrete building slab by providing secondary formwork which separates the higher level and lower level parts of the slab. In the most efficient process, said secondary formwork is specially fabricated and is supported on a plurality of chairs at an appropriate height above formwork for the making of said slab. The secondary formwork and chairs are similarly set in place during the process of installing steel reinforcing bar in the formwork. Many situations occur in which it is necessary to support an arrangement of steel reinforcing bar above formwork for the making of a concrete slab. Rather than supporting such reinforcing bar from the formwork by simply sitting it upon loose chairs, thereby rendering the reinforcing bar likely to be knocked and displaced, a more secure way is to suspend it from a chair which is positively fixed into position. Similarly, anchors and other building elements must be temporarily supported from formwork during the construction process. Excepting some forms of said secondary formwork, all such moulds, secondary formwork, chairs, steel reinforcing bar, anchors and other building elements remain embedded in a concrete building slab after its pouring and curing. To permit adjustment for variations in height of said formwork, said chairs temporarily supporting said moulds, secondary formwork, steel reinforcing bar, cast-in anchors or other building elements have optionally been made adjustable in height.

The described methods supplant methods hitherto used which are time-consuming and inefficient in their use of trades personnel and materials, often requiring the re-attendance of several trades at a building site. Additionally, irregularities in the finished surfaces of cast in-situ concrete slabs may require subsequent correction by the removal of concrete. When it is considered that a multi-storey building may require several thousand lineal metres of such moulds, secondary formwork or steel reinforcing bar, the magnitude of the potential loss due to inefficiency will be readily appreciated.

In Australian Patent Application number 2014213545, an embodiment of screw-adjustable chair is claimed, said embodiment being depicted at Figure 1 hereof. In this embodiment, baseplate 2 is fixed to formwork 1 by suitable fastening (positions indicated in broken line as 3). Ferrule 4 provided with a threaded bore is welded to said baseplate and threaded rod 5 is screwably engaged with said threaded bore and is locked into place by locknut 6 screwed and tightened against the upper edge of said ferrule. In the embodiment depicted, a mould 9 for the creation of a sill or hob on a cast-in-situ concrete building slab is fixed to the upper end of said threaded rod by means of nuts 7, 8 tightened against each other to imprison a lower panel of said mould and locate it at the desired height on said threaded rod. While said chair confers the advantage of height adjustability of an object it supports, the typical length of said threaded rod renders it prone to bending damage if knocked, such damage permitting, for example, a mould or secondary formwork as described above to be displaced from its correct alignment. In the same patent application, another embodiment of chair is claimed, said embodiment being depicted at Figure 2 hereof. In this embodiment, chair column 10 is made from a metal tube of suitable cross-sectional shape and is fixed to baseplate 11 by welding at point 14. Said baseplate is supported above formwork 1 on three or more downwardly-directed legs 12 formed on or fixed to the edges of said baseplate. Said legs are contracted at their lower ends into short, narrow parts 15, a concrete-coloured polymer cap 16 being fixed to the ends of said short, narrow parts, said polymer caps being inconspicuous when said formwork is stripped away. Said baseplate is fixed to said formwork by suitable fastenings (positions indicated in broken line as 13). Experience has shown that the said chair embodiment incorporating a raised, multi-legged baseplate is more positionally stable in service than the said chair embodiment incorporating a baseplate fixed directly to said formwork and supporting a column in the form of a threaded rod. However, the former lacks the height adjustability of the latter. Experimentation has demonstrated that a combination of the two embodiments provides both positional stability and height adjustability, the shorter length of said column rendering it less likely to sustain bending damage. Said experimentation has also led to development of a number of combination embodiments.

The object of the present invention is to provide a chair for the temporary supporting of moulds for the creation of sills or hobs on cast-in-situ concrete building slabs, for the temporary supporting of secondary formwork for the creation of step level changes in such concrete slabs, for the temporary supporting of steel reinforcing bar above formwork for the making of such concrete slabs, for the temporary supporting of cast-in anchors, or for the temporary supporting of any other building element; excepting some forms of said secondary formwork, all such chairs, moulds, secondary formwork, reinforcing bar, anchor or other building element remaining embedded in a concrete slab following its pouring and curing; said chair being adapted to being installed simultaneously with the fixing of steel reinforcing bar in said formwork; said chair combining the stability of a multi-legged baseplate with the height adjustability of a column in the form of a threaded rod.

According to the present invention, a chair for the temporary supporting of moulds for the creation of sills or hobs on cast-in-situ concrete building slabs, for the temporary supporting of secondary formwork for the creation of step level changes in such concrete slabs, for the temporary supporting of steel reinforcing bar above formwork for the making of such concrete slabs, for the temporary supporting of cast-in anchors, or for the temporary supporting of any other building element comprises a baseplate of several configurations or elements homologous to a baseplate, three or more legs of several configurations and an adjustable-height column in the form of a threaded rod. In its simplest form, said chair incorporates a baseplate in the form of a more or less flat sheet metal panel to which a suitable nut is fixed over a centrally-located aperture, formed on or fixed to the edges of said baseplate being three or more downwardly-directed, sheet metal legs of suitable length, a column in the form of a threaded rod being screwably engaged with said nut. A locknut is optionally provided to lock said column to said centrally-located nut. The lower ends of said legs are optionally turned through an appropriate angle to create feet which abut and may be attached to said formwork. The upper end of said column is adapted to be engaged with any element required to be temporarily supported during the construction process. The lower end of column may be extended downwardly below said base plate and employed to support a threaded ferrule for the temporary supporting of steel reinforcing bar or to temporarily support a threaded anchor element to be embedded in said concrete building slab. As said simple form of said chair is obviously of limited rigidity, a stronger unit is optionally created by providing a thicker, stiffer baseplate of smaller diameter, to the periphery of which are fixed three or more, mechanically strong, splayed legs of suitable length, the lower ends of said legs being turned through an appropriate angle to create feet that abut and may be attachment to said formwork. A centrally-located, vertical threaded bore is provided in said baseplate and a column in the form of a threaded rod is screwably engaged with said threaded bore. Said baseplate is optionally pressed from thick sheet metal, die cast from a suitable metal alloy, turned from solid bar or injection moulded from a suitable engineering polymer and may be round, square, triangular or of other symmetrical geometric planform shape. Said legs are made in a range of lengths for particular applications and are optionally pressed from sheet metal, die-cast from a suitable metal alloy, formed from solid bar of round, square or other cross-sectional shape, fabricated from metal tube or injection moulded from a suitable polymer material. Said legs are fixed to the periphery of said baseplate by suitable fastenings, or by welding, spotwelding, bonding or clamping. Said legs are optionally splayed at angles of up to 45 degrees from the vertical plane and said baseplate is optionally made with an area equal to or small in relation to the footprint area of said chair.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which:

Figure 1 is a transverse cross-sectional view through the vertical centreline of a chair incorporating a column in the form of a threaded rod;

Figure 2 is a partial transverse cross-sectional view through the vertical centre-line of a chair incorporating a baseplate supported upon three or more legs;

Figure 3 is a transverse cross-sectional view through the vertical centre-line of a fabricated chair having greater strength and stiffness;

Figures 3a, 3b and 3c are transverse cross-sectional views on, respectively, A-A, B-B and C-C of the legs of the chair of Figure 3;

Figure 4 is a transverse cross-sectional view through the vertical centre-line of a first chair of the present invention adapted for manufacturing by injection moulding from a suitable polymer material;

Figure 4a is a transverse cross-sectional view on A-A of the leg of the chair of Figure 4;

Figures 4b, 4c and 4d and schematic side views of optional baseplate and leg configurations of die present invention;

Figure 5 is a transverse cross-sectional view through the vertical centre-line of a second chair of the present invention adapted for manufacturing by injection moulding from a suitable polymer material;

Figure 5a is a transverse cross-sectional view on B-B of a leg of the chair of Figure 5;

Figure 5b is a transverse cross-sectional view on A-A through the chair of Figure 5.

No significance should be taken from the fact that the various figures are drawn to differing scales.

With reference again to Figures 1 and 2, baseplate 11 is supported above formwork 1 on three or more downwardly-directed legs 12 formed on or fixed to the edges of said baseplate. Said baseplate is fixed to said formwork by means of fastenings (positions indicated in broken line as 13). In an alternative embodiment (not shown), the lower ends of said legs are turned through appropriate angles to create feet that abut and are fixable by suitable fastenings to said formwork. Nut (depicted in broken line as 17) takes the place of threaded ferrule 4 and is fixed to said baseplate over a centrally-located aperture (not shown) and column (depicted in broken line as 5) in the form of a threaded rod is screwably engaged with said nut. Depending upon the strength of the material used and the width of said baseplate, it typically has a thickness falling in the range 0.5 to 20.0 millimetres

With reference to Figure 3, chair 18 comprises baseplate 19 supported from formwork 1 on three or more, splayed, equally-spaced legs 20. To render it capable of sustaining higher loadings, said baseplate is made in solid or partially-solid form, said baseplate being smaller in diameter, thicker and stiffer than the simple sheet metal baseplate of Figure 2. Said base plate is optionally made by pressing from sheet metal, by die casting from a suitable metal alloy, by turning from solid bar or by injection moulding from a suitable polymer material and may be of round, square, triangular or other symmetrical, cross-sectional shape. Where said baseplate is pressed from sheet metal, in the preferred embodiment, the thickness of said metal typically falls in the range 0.5 to 5 millimetres. Where it is made from pressed metal, baseplate 19 takes the form of a flat panel surrounded by a raised flange and with a centrally-located, raised, tubular part which is internally threaded. In the preferred embodiment, baseplate 19 in its partially solid and solid forms typically has a ratio of depth to width falling in the range 1:2 to 1:10 and may be extended in width or diameter to have the same area as the footprint area of said legs. The footprint area of said legs should be taken to be the area of a circle passing through the lower ends of said legs (at the inner ends of feet 23). Threaded bore 25 passes centrally and vertically through said baseplate and column 5 is screwably engaged with its thread.

Said legs are made by folding sheet metal pre-forms to produce a more or less flat-bottomed, U-shaped channel comprising outer panels 21 stiffened by side webs 22. Said side webs narrow progressively from the top towards the bottom of said legs and the lower ends of said legs are turned through an appropriate angle to create feet 23 that abut and are fixable to said formwork by means of suitable fastenings (positions depicted in broken line as 24). Said legs are made in a range of lengths for particular applications and, in alternative embodiments (not shown), are die-cast from a suitable metal alloy, formed from solid bar of round, square or other cross-sectional shape, fabricated from metal tube, or injection moulded from a suitable polymer material. Said legs are fixed to the periphery of said baseplate by suitable fastenings, or by welding, spotwelding, bonding or clamping and are optionally splayed at angles of up to 45 degrees. At the upper ends of said legs, said outer panels and said side panels are separated and said outer panel parts projecting upwardly create upper attachment panels 26 orientated parallel with the peripheral surface of said baseplate. In an alternative embodiment (not shown), said baseplate peripheral surface is inclined to the vertical at the angle of splay of said legs. The two separated side webs 22 are turned inwardly through an angle of 90 degrees from a line displaced from being normal to the plane of said leg outer panel by the angle of splay of said legs to create lower attachment panels 27 parallel to the under surface of said baseplate, the ends of said turned side webs being brought into abutment. Said upper attachment panels are then fixed to the peripheral surface of said baseplate and said lower attachment panels are fixed to the under surface of said baseplate, both said fixings being made by means of suitable fastenings, or by welding, spot-welding or bonding. In an alternative embodiment (not shown), a stiff plate is made with localised radial extensions formed on its circumference, said extensions being complementary to and adapted to bear against said lower attachment panels. Said plate is urged against the under surface of said baseplate by a nut screwed and tightened onto the lower end of said column, urging said radial extensions against said lower attachment panels and thereby capturing them between said radial extensions and the under surface of said baseplate. In the preferred embodiment, zones approximately two millimetres in width at the inner ends of said lower attachment panels are displaced downwardly, said downwardly-displaced zones engaging complementary recesses in said plate radial extensions. In an alternative embodiment, localised projections are provided on the lower surfaces of said lower attachment panels, said projections engaging complementary recesses in said plate radial extensions. Engagement of said downwardly-displaced zones or said localised projections with said complementary recesses acts to positively capture said lower attachment panels, any force acting to increase the splay of said legs being resisted by the abutment of said upper attachment panels against the periphery of said base plate. Said baseplate with its said threaded bore is essentially a contracted and combined form of the baseplate and nut arrangement of Figure 2 and is homologous with those features.

With reference to Figures 3a, 3b and 3c, side webs 22 of legs 20 narrow progressively from the top towards the bottom of said legs.

With reference to Figures 4, 4a and 4e, chair 28 comprises body part 34 supported upon three or more, elongated, equally-spaced legs 29 in splayed or parallel arrangement. Said legs may be straight, curved or cranked and, in a first embodiment, have any simple cross-sectional shape. Said body part is optionally made round, square, triangular or of other symmetrical cross-sectional shape and supplants the baseplate of Figure 3. Said body part and said legs are made in monolithic form. In a second embodiment providing increased stiffness with reduced weight, said legs comprise elongated rails 30 stiffened by webs 31 formed medially on their inner surfaces. In a third embodiment, said legs comprise rails 53 of a V-shaped transverse cross-sectional shape stiffened by webs 54 formed medially on their inner surfaces to provide a broad arrow-type transverse cross-sectional shape. Said legs comprise two or more elongated elements intersecting to create symmetrical cross-sectional shapes, including said T-shaped or broad arrow cross-sectional shapes. Said webs are fixed to said body part and, below said body part, said legs are cranked with said webs and said rails deflected to take up the angle of splay of said legs. In an alternative embodiment (not shown), said legs are made straight, their inclination being achieved by an appropriate radial extension of said webs at said body part. The lower ends of said legs are turned through an appropriate angle to create feet 32 that abut and are fixable to formwork 1 by means of suitable fastenings (positions depicted in broken line as 33). Threaded bore 37 passes centrally and vertically through said body part and column 5 is screwably engaged with said thread. In the preferred embodiment, body part 34 has a ratio of depth to width typically falling in the range 1:1 to 5:1. Said embodiment is adapted to be made by injection moulding from a suitable thermoplastic polymer material with suitable draft being provided to permit vertical separation of a two-piece die. Said body part with its said threaded bore and legs is essentially a contracted and combined form of the baseplate, nut and leg arrangements of Figures 1 and 2 and is homologous with those features.

With reference to Figures 4b, 4c and 4d, said chairs are optionally made in a variety of configurations. In the configuration depicted in Figure 4b, said baseplate is made with the same area as the footprint area of said legs (as defined above), said legs being disposed vertically. In the configuration depicted in Figure 4c, said baseplate is made smaller in area and said legs have a small splay angle. In the configuration depicted in Figure 4d, said baseplate is made even smaller in area and said legs have an increased splay angle. With further reference to Figure 4d, in an alternative embodiment, said legs are splayed in the normal way for part of their upper length with a lower part (depicted in broken line as 35) descending at a lesser angle of splay or descending vertically.

With reference to Figures 5, 5a and 5b, chair 38 comprises horizontally-disposed panel 40 supported from formwork 1 on three or more, splayed, equally-spaced legs 39. In the preferred embodiment, said panel typically has a thickness in the range 3.0 to 10 millimetres. Said panel is optionally made round, square, triangular or of other symmetrical planform shape. Said legs comprise rails 41 stiffened by webs 42 formed medially on their inner surfaces. The lower ends of said legs are turned through an appropriate angle to create feet 43 that abut and are fixable to formwork 1 by means of suitable fastenings (positions depicted in broken line as 44) passing through apertures 52 in said feet. Fixed to the upper surface of said panel and extending upwardly above each said leg are buttress pieces 45. Located within the inner, vertically-arranged edges 47 of said buttress pieces and resting upon the upper surface of said panel is support block 46. Said support block is optionally made round, square, triangular or of other symmetrical cross-sectional shape. Threaded bore 48 passes centrally and vertically up through said support block and column 5 is screwably engaged with said thread. Any force acting to increase the splay of said legs is resisted by the abutment of said buttress pieces against the external surfaces of said support block. In the preferred embodiment, support block 46 has a ratio of depth to width typically falling in the range 1:1 to 5:1. In an alternative embodiment (not shown), the inner edges of said buttress pieces are joined by an approximately cylindrical form made integral with them, said cylindrical form being shaped to slidingly accommodate said support block. The making of said support block removable and replaceable allows a variety of embodiments of fixed and height-adjustable configurations of said column to be readily installed in said chair. Said panel supporting said support block is equivalent to the baseplate and nut arrangement of Figure 2 and is homologous to it.

In the construction of reinforced concrete structures, many situations exist in which it is necessary to support steel reinforcing bar above formwork for the creation of a cast-in-situ concrete building slab. Rather than simply sitting said reinforcing bar loosely upon an object of suitable height, more positive support may be achieved by screwably engaging threaded bore 50 of ferrule 49 on the lower, threaded end of column 5. Said ferrule is provided with one of more, suitably-orientated apertures 51 to accept and support said reinforcing bar. Said embodiment is adapted to be made by injection moulding from a suitable thermoplastic polymer material with suitable draft being provided to permit the vertical separation of a two-piece the die.

Where said chair is made by injection moulding in a polymer material, small projections are optionally provided on the underside of said feet of said legs to raise said feet above said formwork and, thereby, above the lower surface of a said concrete slab.

In use, adjustment of the height of a building element supported from said chair is effected by screwing said column up or down, as required. Said column is optionally made from any suitable material, including metal alloys and polymer materials and in solid or hollow form. Flats or hexagonal shapings to permit engagement of turning devices are optionally incorporated into said column.

The present invention should be taken to include any feasible combination of the features described herein.

Claims

1. A mould and chair combination for the formation of a reinforced raised sill or hob on the surface of a concrete building slab during its casting in-situ, said mould comprising two generally parallel, continuous side members joined in fixed spatial relationship by rigid spacer members welded to them, the width of said spacer members (measured parallel to the longitudinal axis of said sill or hob) being such that they offer no impediment to the flow of concrete entering from above and passing down through said mould to formwork below upon which said slab is to be formed, thereby making the concrete within said filled mould contiguous and monolithic with that of said concrete slab beneath; said mould being temporarily supported from formwork on a plurality of discrete chairs; each said chair comprising a body part, a threaded bore passing centrally and vertically through said body part, said body part being supported above said formwork on three or more equally-spaced legs in splayed or parallel arrangement; said body part and said legs being made in monolithic form; said legs being elongated and made straight, curved or cranked and having a simple transverse cross-sectional shape or comprising two or more elongated elements intersecting to create symmetrical cross-sectional shapes, including T-shaped or broad arrow-shaped; a column in the form of a stiff threaded rod screwably engaged with said threaded bore, said legs being fixable to said formwork, the height of said mould above said formwork being adjustable by screwably displacing said column in an appropriate sense in said threaded bore; the lower ends of said legs being turned through an appropriate angle to create feet abutting and fixable to said formwork.

2. The mould and chair combination of Claim 1 in which the legs of said chair are splayed outwardly from the vertical by any angle between zero and 45 degrees.

3. The mould and chair combination of Claim 1 in the chair of which small projections are provided on the underside of said feet to raise said feet above said formwork and, thereby, above the lower surface of said reinforced concrete structures.

4. The mould and chair combination of Claim 1 in which the body part of said chair is made in solid or partially solid form, having a ratio of depth to width falling in the range 1:2 to 1:10, a threaded bore passing centrally and vertically through said body part.

5. The mould and chair combination of Claim 1 in which the body part of said chair is made solid and having a ratio of depth to width falling in the range 1:1 to 5:1, a threaded bore passing centrally and vertically through said solid body part.

6. The mould and chair combination of Claims 1 and 5 in which the legs of said chair are formed integrally with said body part, said legs comprising rails stiffened by webs formed medially on their inner surfaces, said webs joining the upper parts of said rails to said body part with their width acting to provide spatial separation, said legs being either straight and splayed overall by radial extension of the upper parts of said stiffening webs, or cranked and splayed only below said body part.

7. The mould and chair combination of Claims 1, 5 and 6 in which draft is provided in appropriate parts of said chair to permit the making of said chair by injection moulding in a thermoplastic polymer material using a two-piece die opening by vertical displacement.

8. The mould and chair combination of Claims 1, 5 and 6 in which the legs of said chair are made cranked, being splayed in their upper parts and more or less vertical in their lower parts.

9. The mould and chair combination of Claim 1 in the chair of which the threaded bore of an elongated ferrule is screwably engaged with the threaded, lower end of said column beneath said body part, said ferrule being provided with one of more apertures orientated to accept and support steel reinforcing bar.

10. The mould and chair combination of Claim 1 in the chair of which said column is made from any suitable material, including metal alloys and polymer materials, in solid or hollow form.

11. The mould and chair combination of Claim 1 in the chair of which flats or hexagonal shapings to permit engagement of turning devices are optionally incorporated into said column.

12. The mould and chair combination of Claim 1 in which, where a change in level is required in said concrete building slab, a damming piece extending for a suitable distance above said mould is fixed to a said side member; in order to provide greater stiffness, the free, upper edge of said damming piece being folded through two 90 degree bends to create horizontally-arranged and vertically-arranged returns.

13. The mould and chair combination of Claim 1 in which, where a change in level is required in said concrete building slab, said mould, in hollow or solid form, is employed as a dam to effect said level change, said slab being finished to the upper level of said mould at one side and to a lower level on the other side.