APPARATUS AND METHOD FOR MOULDING A STAIRCASE

Abstract: An apparatus (10) for moulding a staircase comprising a plurality of modules (11-13), each module comprising tread (14) and riser (15) mould parts secured together at, and extending one to each side from, a connection point (18) with a fixed angle of between 0 DEG and 15 DEG between the tread (14) and riser (15), the length of each tread and riser from the connection point (18) being adjustable, and each module (11-13), comprising an individual liner (45) which extends over the tread (14) and riser (15) to cover the tread (14) and riser (15) and there being means (46) located in a space between the tread (14) and riser (15) to maintain the liner (45) taut, the apparatus (10) further comprising a support structure (35) on which the modules (11-13) are mounted generally in a line, there being means to enable the modules (11-13) to be moved along the support structure (35) and to vary the spacing between the modules (11-13) of the mould (10).

Description: Title: Apparatus and method for moulding a staircase Description of Invention This invention relates to an apparatus and method for moulding a staircase particularly but not exclusively in settable material comprising concrete. Such a moulding apparatus is known from prior European patent 0191711. In this previous patent, the mould is provided by a plurality of modules, each module comprising a tread mould part (herein called a "tread") and a riser mould part (herein called a "riser") secured together at, and extending downwardly one to each side from a connection point, with the angle between the tread and the riser being adjustable. The length of each tread and riser from the connection point is adjustable and a liner is provided which extends from one end of the mould to the other end of the mould covering each tread and riser. Between each module, the liner forms a loop which is received around a tensioning roller at each end of the mould, so that the liner can be maintained taut by applying tension. By virtue of the lengths of the treads and risers being adjustable, and the angle between the treads and risers of each module being adjustable, a staircase can be produced to a wide variety of sizes and configurations, to suit particular applications. Where a plurality of generally identical staircases are provided for a single building construction, these can be manufactured using the moulding apparatus without having to construct separate formwork on site, for each staircase. The arrangement described in European patent 0191711 however has disadvantages. The angle between the tread and the riser in each module has been made adjustable so as to enable the foot of each riser in the eventual staircase, to be positioned beneath the tread of the next highest step, by distance of 25 millimetres. This is a safety requirement for staircases. However, to make the angle between the tread and the riser adjustable in this way, significantly increases the cost of the mould. Also if the liner becomes damaged anywhere along the length of the mould, the entire liner needs to be replaced, which is again expensive. Proposals have previously been put forward to enable a section only of the liner to be replaced but these have not been entirely satisfactory. According to a first aspect of the invention we provide an apparatus for moulding a staircase comprising a plurality of modules, each module comprising tread and riser mould parts secured together at, and extending one to each side from, a connection point with a fixed angle of between 0° and 15° between the tread and riser, the length of each tread and riser from the connection point being adjustable, and each module comprising an individual liner which extends over the tread and riser to cover the tread and riser and there being means located in a space between the tread and riser to maintain the liner taut, the apparatus further comprising a support structure on which the modules are mounted generally in a line, there being means to enable the modules to be moved along the support structure and to vary the spacing between the modules of the mould. Thus in apparatus in accordance with the invention, the angle between the tread and the riser for each module, is fixed. Particularly for a staircase in which the risers are undercut, the applicants have found that if this angle is fixed, rather than being adjustable as in prior art apparatus, an undercut of about 25 millimetres for the foot of a riser relative to the tread of the next step, in the eventual staircase, can be achieved for most usual tread/riser sizes. By virtue of the lengths of the treads and risers being adjustable, it is still possible to provide a wide range of sizes of staircases to suit different situations, using the apparatus of the invention. Furthermore, because the means which maintain the liner taut is positioned below the connection point of a tread and riser of a module, the mechanisms involved can be made simpler and more accessible than in prior art proposals. In a preferred arrangement, the fixed angle between the treads and risers of the modules is between 5° and 10° one more preferably is about 7°. The length of at least one of the tread and riser of each module may be telescopically adjustable. For example, the tread and/or riser may comprise an outer part and an inner telescoped part with there being means to secure the inner part relative to the outer part in a desired position. If desired, any step in the upper surface of the tread and/or riser occasioned by the inner part being telescoped outwardly of the outer part, may be filled in with a suitable infill. Each individual liner may comprise a sheet of material which is impervious to settable material which is to be cast into the mould of the apparatus, and the means to maintain the liner taut may comprise a clamping assembly which retains opposite edges of the sheet of material, with the clamping assembly being resiliently biased in a direction away from the connection point. Thus by releasing the opposite edges of the sheet from the clamping assembly, and moving the adjacent modules away, the liner for a single module can relatively easily and quickly be replaced without affecting the liners of any of the other modules. The clamping assembly may be mounted on the module. The support structure may comprise at least one rail and each module may have at the end of the tread and riser remote from the connection point, roller means which roll in or on the rail whereby the modules are movable along the support structure. The distance by which adjacent modules may be separated, may be restricted, for example by means of adjacent modules being connected together by slotted plates, axles which carry the rollers being received in the slots, so that the amount which adjacent modules can move apart is restricted by the lengths of the slots. Means may be provided to close sides and ends of the mould to provide a moulding recess into which settable moulding material, typically concrete, is in use cast and to include integral landings at one or both ends of the staircase. Reinforcement may be positioned in the moulding recess as desired to achieve a staircase having an adequate rated strength. In a preferred arrangement, the means which close at least one of the sides of the mould is movable generally horizontally into an operative position such that the width of the staircase to be produced by the mould, can be selected as desired. Although the modules may be urged together such that the liner of one module intimately contacts the liner of the next module, so that there is no gap for settable moulding material to fall between the modules, if desired, nosing elements may in use be positioned between adjacent modules to close any gap between a liner over a tread of one module and a liner over a riser for an adjacent module, this is to act as a seal to prevent the cost material seeping between the modules. The sizes and shapes of the nosing elements may of course be selected to achieve a staircase having a desired nosing shape on each of the steps. According to a second aspect of the invention we provide a method of moulding a staircase utilising an apparatus according to the first aspect of the invention comprising adjusting the lengths of the treads and risers of each module to desired lengths, moving the modules along the support structure into close relationship with each other, closing the sides and ends of the mould, and casting into the mould settable material and permitting the settable material to set. The invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side illustrative view part of an apparatus for moulding a staircase in accordance with the invention with sides removed for clarity; and Figure 2 is an end sectional view of part of the apparatus of Figure 1 along the lines 2-2. Referring to the drawings, an apparatus 10 for moulding a staircase upside down comprises a plurality of modules, one of which is detailed in the drawings at 12, and modules to either side of module 12 are illustrated in part only, at 11 and 13. Each module 10 of the apparatus is generally of identical configuration and hence only module 12 will be described in any detail. Module 12 comprises a tread mould part 14 and a riser mould part 15, the left end of the apparatus 10 in use being the upper end of the staircase produced on the apparatus 10, and the right hand end of the apparatus 10 being the lower end of the staircase to be produced. In the apparatus 10, the staircase is produced upside down i.e. the moulded settable material which is introduced into the mould, which is in contact with upper surface 16 of the tread 14, provides a tread of a lower step, whilst the settable material which in use sets on upper surface 17 of the riser 15 provides the riser towards the next highest step. In the arrangement of the invention, the tread 14 and riser 15 are secured together at a connection point 18 such that the angle between the tread 14 and riser 15 is fixed at about 7°. The angle between the tread 14 and riser 15 may be anything between about 0° and 15°, 0° where the risers are intended to be vertical, up to 15° where a large undercut is required. Preferably the angle is fixed between 5° and 10°. The lengths of the tread 14 and riser 15 are telescopically adjustable so that a tread 14 and riser 15 of a desired dimension can be provided. To achieve this, the tread 14 comprises a pair of outer plates 20 and 21, which receive between them an inner plate 22 which is slidable between the outer plates 20 and 21. A clamping device 23 such as a wedging mechanism is provided so that the position of the inner plate 22 relative to the outer plates 20 and 21 can be set. As shown in the drawings, a step 24 which would otherwise occur in the tread surface of the staircase, by virtue of the step between the outer plate 20 of the riser 15, and the inner plate 22, is filled with an infill 25, which in this example is made of timber, but could be made in another material as desired, and is sized appropriately to suit the length of the tread 14. Similarly, the riser 15 comprises a pair of outer plates 26, 27 which receive telescopically between them, an inner plate 28, with there being a clamping device 29 so that the position of the inner plate 22 relative to the outer plates 26, 27 can be set. Again as seen in the drawings, a timber or other infill 30 is provided to fill any step 31 where the outer upper plate 26 ends and the inner plate 28 continues. At the lower end of the tread 14 there are mounted, a pair of rollers 33 one at each side of the moulding apparatus 10, and at the lower end of the riser 15, likewise there are provided pairs of rollers 34 one at each side of the apparatus 10. The rollers 33 and 34 permit movement of the module 12 along a support structure 35 which in this example, comprises a module carrier track which includes a pair of rails 37, 38. The rollers 33, 34 are provided on an end of a respective axle 41/42 secured to the inner tread plate 22, or the inner riser plate 28 respectively, and the amount adjacent modules 11, 12, 13 are permitted to be separated is restricted, by virtue of the axles 51/42 of adjacent modules 11, 12, 13 being received in respective slots 39, 40 of plates P connecting the modules 11, 12, 13 together. Hence the extent of separation of adjacent modules 11, 12, 13 is restricted by the respective slots 39, 40. Each module 12 further comprises an individual liner 45 which comprises a sheet of material which is impervious to the settable material which is cast into the mould in use. The liner 45 covers the tread 14 and riser 15, and passes around the respective axles 41, 42. A clamping assembly 46 is provided below the connection point 18 in a space S between each tread 14 and riser 15. The clamping assembly 46 is secured to a brace T which interconnects the inner plates 21, 27 of the tread 14 and riser 15 respectively and comprises a pair of liner clamp plates 47, 48 which retain between them, the edges of the liner 45. The clamp plates 47, 48 are then biased resiliently downwards by means of a spring 49 received in a spring casing 50 secured to brace T. Thus by virtue of the clamping assembly 46, the liner 45 is maintained taut about the tread 14 and riser 15 of the module 12. Furthermore, in the event that the liner 45 of module 12 becomes damaged in use, the liner 45 can be replaced relatively simply, by releasing the edges of the liner 45 sheet from the between the clamp plates 47 and 48, when the modules 11, 12 and 13 are moved apart from one another along the support structure 35. In use, whereas the modules 11, 12 and 13 may be moved together such that the liner 45 of one module, e.g. module 12, engages with the liner 45 of the adjacent module 13, to prevent settable material cast into the mould falling through any gap between the modules 12 and 13, preferably, nosing inserts 51 are provided between adjacent modules. The shape (radius) of the upper surface 52 of the nosing inserts 51 may be chosen so that a step is provided in the staircase having a desired nosing shape. It will be appreciated that the modules 11 to 13, particularly for a long staircase, will be very heavy to move along the support structure 35. Accordingly, preferably movement of the modules 11 to 13 is achieved by some motive means. The apparatus 10 is used as follows. First, the length of the tread 14 and riser 15 of each module 11 to 13 need to be adjusted to provide a tread 14 and riser 15 for each step, of a desired length. Preferably, the tread and riser lengths of each of the modules is arranged to be the same so that in the eventual staircase, the treads and risers will be of the constant dimension throughout. This adjustment is achieved by separating modules 11 to 13 to the maximum extent permitted by the respective slots 39, 40, when the nosing inserts 51 would be removed. When the tread and riser sizes have been adjusted, the modules 11 to 13 are closed up and the nosing inserts 51 inserted so that settable material cannot escape from the mould by falling through any gap between any of adjacent modules 11 to 13. Next, the ends of the mould are closed by any suitable means as are the sides of the mould and a landing is included at one or both ends of the staircase if desired. Preferably the sides of the mould are closed by means of mould side panels 60 which preferably are faced with plywood or another suitable material. Both of the panels 60 are shaped at the lowest edges to conform to the shape of the staircase so that the lower ends of such side panels are engaged with each of the tread 14 and riser 15 surfaces 16, 17 of the modules 11 to 13. Of course such side panels would need to be provided for a particular staircase configuration and are not universally usable with the wide variety of staircase configurations the apparatus 10 is able to produce. In this way, the mould side panels can be located across the mould so that a staircase of a desired width can be provided. The apparatus 10 will thus present a moulding recess to receive settable material such as concrete. If desired or necessary, reinforcement may be provided within the moulding recess, the reinforcement being embedded in concrete which is eventually cast. There are modifications which may be made without departing from the scope of the invention. For example, any means alternative to that described for achieving adjustment of the lengths of the treads 14 and risers 15 of the modules, 11-13 may be provided, as can alternative means for fixing the position of any inner plate 22, 28 relative to respective outer plates 20, 21; 26, 27. Although rollers 33 and 34 have been described receivable in slots 39, 40 of rails 37, 38 of the support structure 35, any other means which permits movement of the modules 11 to 13 so as to restrict the distance by which the modules 11 to 13, may be separated, may be provided. Any alternative means for maintaining the individual liners 45 taut on the modules 11 to 13 may be provided. Nosing inserts 51 with upper surfaces 52 of alternative radius to those shown in the drawings, can be used so as to achieve a step nosing radius in the final staircase, of a desired radius. Utilising the apparatus and method of the invention a staircase having any number of steps may be provided depending on where the ends of the mould recess are closed, the length being limited only by the number of modules and the extent of the support structure 35. It can be seen in Figure 2, that the module carrier track 36 is mounted on a base channel 63 which may for example be a concrete, metal or other structure sufficient to support the apparatus 10 at each of the mould. Alternative module carrier track configurations may be provided which permit movement of the modules 11 to 13 along the support structure 35. Although the invention has been described in relation to a specific arrangement in which the staircase is cast upside down, the invention may be applied to casting a staircase on end, in which case the tread 14 and riser 15 mould parts would be arranged generally vertically with the clamping assembly 46 extending generally horizontally and to the side of the connection point 18 rather than below it. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS 1. An apparatus for moulding a staircase comprising a plurality of modules, each module comprising tread and riser mould parts secured together at, and extending one to each side from, a connection point with a fixed angle of between 0° and 15° between the tread and riser, the length of each tread and riser from the connection point being adjustable, and each module comprising an individual liner which extends over the tread and riser to cover the tread and riser and there being means located in a space between the tread and riser to maintain the liner taut, the apparatus further comprising a support structure on which the modules are mounted generally in a line, there being means to enable the modules to be moved along the support structure and to vary the spacing between the modules of the mould. 2. An apparatus according to claim 1 wherein the fixed angles between the treads and risers of the modules are between 5° and 10°. 3. An apparatus according to claim 1 or claim 2 wherein the fixed angles between the treads and risers of the modules are about 7°. 4. An apparatus according to claim 1 or claim 2 or claim 3 wherein the length of at least one of the tread and riser of each module is telescopically adjustable. 5. An apparatus according to any one of the preceding claims wherein each individual liner comprises a sheet of material which is impervious to the settable material to be cast into the mould. 6. An apparatus according to claim 5 wherein the means to maintain the liner taut comprises a clamping assembly which retains opposite edges of the sheet of material and the clamping assembly being resiliently biased in a direction away from the connection point. 7. An apparatus according to claim 6 wherein the clamping assembly is mounted on the module. 8. An apparatus according to any one of the preceding claims wherein the support structure comprises at least one rail and each module has at the end of the tread and riser remote from the connection point, roller means which roll in or on the rail whereby the modules are movable along the support structure. 9. An apparatus according to any one of the preceding claims wherein the distance by which adjacent modules may be separated is restricted. 10. An apparatus according to any one of the preceding claims wherein means are provided to close sides and ends of the mould to provide a moulding recess into which settable moulding material is, in use, cast. 11. An apparatus according to claim 10 wherein at least one of the sides of the mould is movable generally horizontally into an operative position. 12. An apparatus according to any one of the preceding claims which includes nosing elements which, in use, are positioned between adjacent modules to close any gap between a liner over a tread of one module and a liner over a riser of an adjacent module. 13. An apparatus for moulding a staircase substantially as hereinbefore described with reference to and as shown in the accompanying drawings. 14. A method of moulding a staircase utilising an apparatus according to any one of the preceding claims, comprising adjusting the lengths of the treads and risers of each module to desired lengths, moving the modules along the support structure into close relationship with each other, closing the sides of the mould, and casting into the mould settable material, and permitting the settable material to set. 15. A method of moulding a staircase substantially as hereinbefore described with reference to the accompanying drawings. 16. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

Inventors: OGDEN PETER WALLIS, OGDEN, PETER, WALLIS
Applicants: OGDEN PETER WALLIS, TARMAC UK LTD, OGDEN, PETER, WALLIS, TARMAC HEAVY BUILDING MATERIALS UK LIMITED
Application year: 1996
Main classification: B28B7
IPC codes: B28B7