"STAIR FORMING APPARATUS AND RELATED METHODS"

The present invention relates to adjustable stair forming apparatus and related methods for moulding concrete, or similar settable materials, to define a flight of stairs wherein adjustments to the apparatus can allow for differing flights to be made having different width, tread length, riser height, nosing length, stair pitch, landings and similar.

Traditionally when concrete, or other similar formable or settable material is used to form, stairs, a mould is made for the exact form of the flight of stairs required. Concrete is then poured into the mould. The concrete is then allowed to set and the resulting flight of stairs is removed from the mould.

This is an expensive method of forming stairs, as for each different flight of stairs a new mould is required.

There has therefore been a long felt want for a product that will allow numerous different stair shapes to be formed without needing to invest in numerous different moulds.

Typically moulds have been made from wood to keep the cost down. In moulding environments wood has a limited life. It eventually breaks down from wear and tear, requiring a new mould to then be made.

US 5,133, 530 discloses a stair forming apparatus. A key short coming of US 5,133, 530 is its inability to adjust the nosing of the stairs. The nosing is the distance of the overlap of two adjacent stairs treads. They specifically state they can only produce a right angle stair profile. The stair codes govern the maximum and minimum lengths of the treads, risers and nosing for any particular stair type eg. public access, main private stairways etc. The ability to extend the actual tread length by adding a nosing is very helpful to architects and designers when limited room is available.

In addition the individual units in US 5,133,530 must all be set at the same unit pitch, there is no ability to vary the pitch between units, only globally of all the units. This also increases the difficulty of adding and removing units to form more or less stairs. The mechanism used in their apparatus also increases the cost of the apparatus and makes it less portable.

It is therefore an object of the present invention to provide a stair forming apparatus and/or related methods that at least overcomes some of the problems of the prior art, or to at least address the above desiderata, or at least provide the public with a useful choice. In this specification if and where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

In a first aspect the present invention may be said to consist in an adjustable stair forming apparatus, to form a flight of stairs of a settable material, each stair of said flight including a tread and a riser, said apparatus comprising or including, a frame, a plurality of forming units to receive the settable material, each forming unit reconfigurably mounted from said frame in:

(a) a pivotal manner about an axis parallel to pivot axes of the other forming units, said axis extending in a direction parallel to the width direction of the flight of stairs to be formed, and/ or

(b) a translational manner in a direction perpendicular to the width direction each of said forming units comprising,

(a) a tread forming member defining a tread forming surface with an upper edge substantially parallel to a lower edge, and

(b) a riser forming member defining a riser forming surface with a first edge bearing on the tread forming member and disposed at or toward said upper edge, and a bearing edge parallel to and distal from said first edge, said riser forming surface at least in part co-extending in said width direction with said tread forming surface,

said plurality of forming units each arranged relative said frame with said bearing edge of one said forming unit resting on a said tread forming surface of an adjacent said forming unit, said riser forming member adjustably mounted relative said tread forming member to.allow the angle between said riser forming surface and said tread forming surface to be varied, wherein prior to receiving said settable material, said forming units can be configured to a desired configuration, adjustment of said apparatus allowing forming of flights of stairs that differ in shape. Preferably said tread forming member is pivotally mounted on a first said axis

("first axis") to said frame from or toward said lower edge of said tread forming member.

Preferably said forming units act in concert to collectively provide a forming surface. Preferably said apparatus has adjustment to allow forming of different flights of stairs that differ in shape in any one or more of the following,

(i) Number of stairs

(ii) Riser height

(iii) Tread depth (iv) Stair width,

(v) Size of landing or landings, or

(vi) Stair angle.

Preferably said direction perpendicular to the width direction is in the flight or pitch line direction ("first direction") of said flight of stairs. Preferably said nosing is adjusted with an adjustable stop behind each said riser forming member.

Preferably said number of stairs is adjusted by removing or adding one or more forming units.

Preferably said riser height is adjusted by varying the height of said riser forming members.

Preferably said first edge is adjustably mounted from or toward said upper edge by an abutment at or toward said upper edge.

Preferably said tread depth is adjusted by varying the point at which said bearing edge rests on said tread forming surface. Preferably said point at which said bearing edge rests on said tread forming surface can be varied by varying said angle of said plurality of forming units about said parallel axes relative to said frame.

Alternatively said point at which said bearing edge rests on said tread forming surface can be varied by varying the distance in said plane between said forming units. Preferably said stair width is adjusted by a pair of side mould surfaces parallel to said first direction, both profiled to seal against said plurality of forming units and at least one of which is adjustable in location on said forming units.

Preferably said flight of stairs is formed upside down in said stair forming apparatus. Preferably said axes are parallel to said width direction.

Preferably said plane is substantially hori2ontal.

Preferably said tread forming member is also pivotally mounted on a second said axis ("second axis"), parallel to said first axis, to said frame from or toward said upper edge of said tread forming member. Preferably said frame consists of a first and second side frames that each run along a first and second parallel side of said plurality of forming units, in said first direction that is perpendicular to said width direction.

Preferably said tread forming members of said plurality of forming units are each pivotally connected, direcdy or indirectly, between said first and second side frames. Preferably said tread forming members are each pivotally connected to brackets that in turn are translationally connected to said side frames.

Preferably said angle is varied by moving said first axis relative to said second axis in a direction perpendicular to said width direction and said first direction.

Preferably said first axis and said second axis are each mounted to relatively movable parts on each of said first and second side frames, relative movement of said movable parts moving said first axis relative to said second axis.

Alternatively said angle is varied by moving said first axis relative to said second axis in a direction parallel to said second direction.

Preferably said frame is extendable by adding further sections of frame thereto.

Preferably there is a seal formed between said bearing edge and said tread forming surface.

Preferably there is a seal formed between said first edge and said upper edge.

Preferably said seal is sufficient to substantially prevent said settable material passing therethrough.

Preferably there are side brackets to hold said side mould surfaces. Preferably said side brackets are adjustable in length in said first direction.

Preferably said side brackets are mounted to be biased inward or outward along said first direction.

Preferably said side brackets are biased by wedges that can be reversed to bias said side brackets inwards or outwards in said first direction. Preferably a landing surface(s) can be located at the head and/or bottom of said stair forming apparatus to enable forming of landings at the head and/or bottom of said flight of stairs.

Preferably said landing surfaces adjustably angle downward at the bottom, and adjustably angle upward at the top of said stair forming apparatus relative to said frame.

Preferably said landing surfaces co-operate with additional landing surfaces and closing surfaces to form a cavity to receive said settable material that, once set, forms said landing(s) of said flight of stairs.

Preferably any of the forming surfaces of said stair forming apparatus can be stiffened at least in bending by addition of structural beams.

Preferably said structural beams are attached by clamping to said forming surface.

Preferably said adjustment of said back stop and said adjustment means of said relatively movable parts is by complimentary threaded components.

Preferably said tread forming members and said riser forming members are substantially rectangular in shape.

In a further aspect the present invention consists in an adjustable stair forming apparatus, adapted to form a flight of stairs of a settable material, said flight of stairs including a series of treads interconnected by intermediate risers, said apparatus comprising or including, . a frame to support a series of forming units, a plurality of forming units, acting in concert to collectively provide a forming surface, each of said forming units, including,

(a) a tread defining formwork that includes a rectangular shaped tread forming surface, slidably and pivotally mounted to said frame from or toward a first major edge of said tread forming surface, and

(b) a riser defining formwork that includes a rectangular shaped riser forming surface with a first major edge adjustably mounted from or toward the opposite major edge of said tread forming surface, said riser forming surface at least in part co- extending widi said tread forming surface in a stair width direction, preferably said riser forming surface including a bearing surface parallel to and distal from its said first major edge, said plurality of forming units each adjustably held in an array by and/or relative to said frame with said bearing surface of one said forming unit supported by said tread forming surface of the adjacent said forming unit. In yet a further aspect the present invention consists in adjustable stair moulding apparatus adapted to form a flight of stairs, comprising or including, a series of forming units that are adjustable to allow a flight of stairs defining any number of steps, and that are adjustable to allow, within a flight of stairs, variation in the set of steps forming the flight, of, a tread depth, a riser height, or a tread width, said forming units being adjustable to allow moulding of a wide range of flights of stairs from the one apparatus. In yet a further aspect the present invention consists in a stair flight forming apparatus to form a flight of stairs of a settable material, said flight including a

plurality of stairs each including a tread and a riser that extend substantially perpendicular to each other, adjustment of said apparatus allowing for the forming of different flights of different shaped treads and/or risers to occur, said apparatus including: a frame, a plurality of tread defining formwork elements, each including a tread forming surface to define a said tread of a stair, movably supported by said frame in a spaced apart manner, and at least two sets of a plurality of riser defining formwork elements, each including a riser forming surface to define a said riser of a stair, to be supported by said frame, wherein the angle between a said tread forming surface and a said riser forming surface of each said stair can be maintained perpendicular to each other by virtue of,

(a) an adjustable support of each said tread defining formwork element relative said frame and relative the other said tread defining form work elements, and (b) selection of an appropriate set of said riser defining formwork elements that comprises of riser defining form work elements of a size that can span between adjacent said tread defining formwork elements.

In another aspect the present invention consists in a adjustable stair flight forming apparatus to form a flight of stairs of a settable material, said flight including a plurality of stairs each including a tread and a riser that extend substantially perpendicular to each other, adjustment of said apparatus allowing for the forming of different flights of different shaped treads and/or risers to occur, said apparatus including: a frame, a plurality of riser defining formwork elements, each including a riser forming surface to define a said riser of a stair, movably supported by said frame in a spaced apart manner, at least two sets of a plurality of tread defining formwork elements, each including a tread forming surface to define a said tread of a stair, to be supported by said frame,

wherein the angle between a said tread forming surface and a said riser forming surface of each stair can be maintained perpendicular to each other by virtue of,

(a) an adjustable support of each said riser defining formwork element relative said frame and relative the other said riser defining formwork elements, and (b) selection of an appropriate set of said tread defining formwork elements that comprises of tread defining formwork elements of a size that can span between adjacent said riser defining formwork elements.

In yet another aspect the present invention consists in a method of using an adjustable stair moulding apparatus, to form a flight of stairs of a settable material, each stair of said flight including a tread and a riser, adjustment of said apparatus allowing forming of flights of stairs that differ in shape comprising or including the steps of,

(i) establishing, dependent from a frame, a number of forming units equal to the number of steps required in a flight of stairs to be moulded, each forming unit comprising a tread forming member defining a tread forming surface and a riser forming member defining a riser forming surface,

(ii) configuring the position of said tread forming surface relative to said frame of said forming units to establish the desired rise height and/or run length of said stairs to be formed, (iϋ) locating a riser forming surface between one tread forming member and an adjacent tread forming member,

(iv) defining a stair width to be formed by establishing a desired spacing between side forming surface that together with said forming members define a cavity to receive the settable material, (v) pouring a settable material into the cavity.

Preferably the nosing of said riser forming surfaces is adjustable.

Preferably said nosing is adjusted with an adjustable stop behind each said riser forming surface.

Preferably there is also the step of locating landing forming surfaces at the first (bottom) and or the last (head) forming units prior to pouring or locating said settable material.

Preferably prior to locating said settable material there is the step of locating reinforcing bar or material in said stair forming cavity.

In a further aspect the present invention consists in an adjustable stair forming apparatus, adapted to form a flight of stairs from a settable material, each stair of said flight including a tread and a riser, adjustment of said apparatus allowing forming of flights of stairs that differ in shape, said apparatus comprising or including, a frame, a plurality of supports, each of said supports mounted, either or both,

(a) translationally from said frame to translate parallel to a transverse plane of said frame,

(b) translationally from said frame to translate perpendicular to said transverse, a flexible membrane draped under tension across, and supported by, said plurality of supports, said flexible membrane when under tension presenting at least one each of, a tread forming portion as a substantially planar surface with a first lower edge parallel to said transverse plane, and an upper edge substantially parallel to said first lower edge, and a riser forming portion as a substantially planar surface extending at an angle from said upper edge to a parallel second lower edge, said riser forming surface at least in part co-extending with said tread forming surface, said angle and relative lengths of said riser forming portion and said tread forming portion being adjustable via movement of said supports, said tension of said flexible membrane being variable by adjustable tensioners, said first edge adjustably mounted to allow said riser forming portion to angle, at an acute internal angle relative said tread forming portion, with said second lower edge located toward said first lower edge, thus allowing an overlap of adjacent tread forming portions thus allowing a nosing to be formed between flights of said stairs, and an adjustment means to control said translation of said plurality of supports about said transverse plane relative to said frame.

In another aspect the present invention consists in an adjustable stair forming apparatus as herein described with reference to any one or more of the accompanying drawings.

In another aspect still the present invention consists in a method of using an adjustable stair moulding apparatus as herein described with reference to any one or more of the accompanying drawings.

As used here in the term "surface" can mean one continuous surface whether that surface has sharp discontinuities or bends and may be provided by two or more adjacent members. As used herein the term "and/or" means "and" or "or", or both.

As used herein the term "(s)" following a noun includes, as might be appropriate, the singular or plural forms of that noun.

The term 'comprising' as used in this specification means 'consisting at least in part of, that is to say when interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Preferred embodiments of the present invention are shown in the accompanying drawings whereby: Figure 1 shows at (A) an indicative flight of stairs in side perspective view showing landings and stairs there between, and at (B) a variation whereby the nosing are at an obtuse angle,

Figure 2 shows an exemplary forming apparatus in side isometric view showing the forming surface for moulding the topside of a set of stairs including the top landing and the bottom landing,

Figure 3 shows a further view of the apparatus in the Figure 2 with the addition of top plates located for landing moulding,

Figure 4 shows the detail A of Figure 3,

Figure 5 shows in close up the side view of the stair forming apparatus of Figure 2,

Figure 6 shows detail A of Figure 5,

Figure 7 shows detail B of Figure 6,

Figure 8 shows a close up side profile of a series of forming units, and the pivot points and backside for sliding on various frame members, Figure 9 shows a bottom isometric view of the tread forming surface,

Figure 10 shows detail A of Figure 9,

Figure 11 shows a frame assembly for the stair forming apparatus,

Figure 12 shows detail B of Figure 11,

Figure 13 shows detail D of Figure 11, Figure 14 shows detail C of Figure 12,

Figure 15 shows varying forms of flights of stairs that can be formed with the present apparatus including (A) a flight of stairs with a left hand opening landing and a right hand opening landing; (B) a flight of stairs with centred landings top and bottom; (C) a flight of stairs with right hand opening landings top and bottom; (D) shows the reverse of C with the landings opening to the left top and bottom,

Figure 16 shows further variations including (A) a flight that locates and abuts on separate landings top and bottom (in the particular embodiment showing the bottom landing as a right hand opening one for the flight of stairs) (B) a "U" set of stairs whereby a top landing leads to a flight of stairs with a bottom landing that communicates sideways with the top landing of a further flight of stairs moving down to a bottom landing; (C) a single flight of stairs with inline landings top and bottom (two of which reversed, forming the U shape flight shown in B); and (D) a flight of stairs with a top landing only,

Figure 17 shows a sectional side view of a further configuration of the present invention,

Figure 18 shows a sectional, perspective view of a further configuration of Figure 17,

Figure 19 shows the assembly of a further moulding apparatus in isometric view, using a flexible membrane, Figure 20 shows a side view of the apparatus of Figure 19, with formers, clamps, belt tension adjusters and how the flexible belt is formed and held,

Figure 21 shows close up detail of A in Figure 20,

Figure 22 shows an isometric view of Figure 20,

Figure 23 shows an isometric view of Figure 21, Figure 24 shows in isometric view a possible rail support for the forming apparatus,

Figure 25 shows in isometric view the detail of A in Figure 24,

Figure 26 shows in isometric view the detail of B in Figure 24,

Figure 27 shows in isometric a configuration of the belt support, Figure 28 shows in isometric view the detail of A in Figure 27, and

Figure 29 shows a further stair shape and tread former for forming the stair shape.

A first preferred embodiment of the present invention will now be described with reference to Figures 1 through 16 and 29. A flight of stairs (2) consists of a number of stairs or steps (4). Usually also there is a landing or platform (6) at the top and/or bottom of the flight of stairs (2). The flight of stairs (2) therefore may contain only stairs (4), a number of stairs (4) with a landing (6) at the top, a number of stairs (4) with a landing (6) at the bottom, or a number of stairs (4) with a landing at the top and bottom. Each individual stair (4) consists of a tread (12) and a riser (14). The tread (12) is where a person places their foot. The riser (14) is that portion of the stair that connects the tread (12) to an adjacent tread (12). The overall width (10) of the stairs (4) may be the same as the landings (6). Alternatively the width may narrower or broader depending upon the formation of the flight of stairs (2) required. The overall height of the flight of stairs (2) is called the rise height (37) and the overall length of the stairs is called the run length (39). The ratio of rise height (37) to

run length (39) is called the "rake" or "pitch". Pitch in some instances can also refer to the distance between die tips of two adjacent stairs (4). The number of steps (4) in a flight of stairs (2) is deduced by the number of risers present. Therefore in the example indicated in Figure 1 there are tiiree risers and therefore this is a three step (4) flight of stairs (2). The riser height is the height of any particular riser (14). The tread length or depth is the length overall of the tread.

Figure 2 shows a preferred form of a stair moulding apparatus (1). It is to be understood that the stair moulding apparatus (2) essentially moulds a stair upside down. It receives a settable material such as concrete and once the settable material has cured it is then lifted away from the stair moulding apparatus (1).

The stair moulding apparatus in this embodiment includes a frame (3). The frame consists of a first side frame (57) and a second side frame (59), each side frame having a number of frame members (5). The frame members (5) of the frame (3) sit either side of the forming units (7) and lie in a second direction (53). However in other embodiments they may sit entirely below the forming units (7), or they be partially below and partially beside as the embodiment requires. In particular a middle frame member (5a) is adjustable within the frame (3).

An adjustment means (29) is located to allow adjustment of the frame member (5a) relative to frame (3). The embodiment shown has the adjustable frame member (5a) as the middle frame member. However it is to be understood that this frame member could be the lower frame member, upper frame member or possibly also the only frame member present.

The adjustment means (29) may be a threaded rod and nut. A nut running on the rod is upwardly engaged with the adjustable frame member (5a). In this way the thread of the adjustment means is fixed rigidly to the frame (5). The nut, is rotatable up and down on and relative to the thread. In this way the nut is rotated, moves up the thread, engages the underside of part of the adjustable frame member (5a) and therefore can lift the frame member (5a) upwards. In a similar manner when the nut is spun down the thread of the rod the adjustable frame member (5a) will move downwards. Other equivalents to this adjustment and other ways of achieving it will be obvious to a person skilled in the art. For example, but not limited to, a form of

prime mover may be used, such as an air or hydraulic cylinder to achieve the same result.

As diere is only an upward engagement of the adjustable frame member (5a) to the adjustment means (29) the adjustable frame member (5a) can be lifted up, the adjustment means set in position and then the adjustable frame member (5a) located downwards.

In this way also only one or two of the adjustment means (29) (e.g. at either end of the adjustable frame (5a)) can be moved upwards, set to the desired height and thereafter the remaining adjustment means (29) are then wound up to support the adjustable frame member (5a). The effect of this is discussed below. Shown in Figure 11 is a first frame (3a) and a second frame (3b) joined together at a frame join. It is to be understood that more or less frames (3) can be added to the stair moulding apparatus (1) to enable the moulding of longer flights of stairs (2) as required. In the preferred embodiment there is an overlap or a lap available as shown in close up in Figure 13 of the frame (3a) which can engage a similar complimentary lap in a subsequent frame (3b) to allow connection of as many frames as needed.

The frame join (32) can be seen in this instance as a lap point. Further frame members (5) are located against the lap point and fastened thereto. Fastening can be of any means known in the art. Other ways of attaching the frame members to each other are, for example sleeving, overlapping, welding if a semi-permanent fixture is required and similar.

In the preferred embodiment the frames (3) extend in the vertical plane. The members (5) of the first and second side frames (57) and (59) respectively provide reference surfaces in the horizontal direction. These reference surfaces, when at the same height on the frame, serve to define a plane.

A number of horizontal stands (61) to support the frame members (5) are bolted or attached to a flat horizontal member such as a floor of the moulding room. The frame (3) then supports the plurality of forming units (7) via the frame members (5) in a way that will now be described. It is shown that the frame (3) consists of first and second side frames (57) and

(59) that lay either side of a plurality or series of forming units (7).

An individual forming unit (7) has a tread forming member (78) that defines a tread forming surface (11) and a riser forming member (76) that defines a riser forming surface (13). The tread forming member in one embodiment is pivo table at its lower edge (19) by a lower edge bracket (43). Pivoting is about a first axis that extends in a first direction (51) that joins between and is perpendicular, to each of the side frames, i.e. the transverse direction.

Where the term "width" is used it is to be understood to be transverse to the flight or second direction (53), i.e. in the first direction (51). "Length" is parallel with the frames (5), i.e. in the second direction (53). Height is a term indicating relative distance perpendicular from one tread forming surface to the next tread forming surface. In this context height also refers to the vertical height of a stair when in location on a building.

In the embodiment shown the lower edge bracket (43) is C shaped in cross section and engages the inside of a frame member (5) and hooks around the top and bottom surfaces of the frame member (5). In this way the lower edge bracket (43) is slidably engaged along the frame member (5) that it is attached to. In the preferred embodiment this frame member is the adjustable middle frame member (5a).

In the embodiment shown the lower edge (19) of the tread forming surface (11) is pivo tally engaged with the lower edge bracket (43). The pivoting in this case is on a second axis, parallel to the first axis, these are therefore two parallel axes. The forming unit (7) can pivot relative to, and can also slide relative in a second direction (53) on the frame. The second direction is perpendicular to the width direction and parallel to the longitudinal axis of the frame (3) and frame members (5). The second direction is the direction parallel to the pitch line of the stairs, i.e. that line that connects the tips of the tread forming surfaces.

Each tread forming surface (11) as shown may be made from four millimetre thick steel plate. However any thickness of any particular material will suffice. If the material itself is not strong enough in bending then structural beams (45) (for example shown in Figure 9) can be used to strengthen and stiffen the transverse stiffness of the tread forming surface (11). The tread forming surface also has structural sides (47) that reinforce the edge of the tread forming surface (11).

Therefore, practically any width of tread forming surface can be used and it is only dependent upon the stiffness that can be achieved. The greater the width and/or length of the tread forming surface (11) the greater the number and strength of structural means (45) that can be applied. Therefore it is entirely possible that the current apparatus may find application outside the field of forming of stairs, for example forming grandstand seating or similar.

Located from the distal edge (23) of a tread forming surface (11) is a riser forming member 76 with the riser forming surface (13) thereon. The riser forming surface (13) is or can be adjustably mounted from the distal edge (23). This is to accommodate the riser forming surface (13) being at 90° to the tread forming surface (11) and also to jut forward at a positive angle as seen in Figure 8 or to angle backwards relative to the tread forming surface (11). When angled backwards at an acute angle (i.e. toward the lower edge (19)) this creates a nosing (33) of the stair tread. It may also be desirable to have the riser forming surface (13) angled forwards at an obtuse angle relative the tread forming surface (11) , to form a riser as shown in Figure Ib.

The riser forming surface (13) can have any form of cross section needed. For example Figure 29 shows a riser forming member (13) that has a nosing (33) formed due to its facetted or composite surface "S" form shape. Different height and width riser forming surfaces (13) can also be used as needed for various stair flights formed. In addition any of the surfaces described may be made of multiple parts that present a surface or composite surface.

In addition if needed inserts (74) can be applied to the mould, for example protection for the leading edge of the tread. Such protection strips are known in the art and may simple protect the edge of the formed step from chipping, may add grip, or may have a cushioned region so that a person falling or hitting the step leading edge is likely to be less injured.

Nosing (33) is also referred to hooking or overlapping. It is the distance that one tread length under laps a next tread length above it. Nosing is also referred to as tread protection in the trade.

Figure 10 shows detail of the distal edge (23) showing a further pivotal mounting point (17) and a seal (16). In practice the riser forming surface (13) can be any form of stiff resilient material. For example, wood, medium density fibreboard, steel, aluminium or similar may be used. In the preferred embodiment a wood material is used. In another preferred embodiment it is made from 6mm thick plate steel.

The riser forming surface (13) butts against a resistant edge (18) of the distal edge (23) as shown in Figure 10. Therefore the weight of the settable material once located in the stair moulding apparatus (1) will bear against the forming surface (left hand side of the riser forming surface (13) when viewed in Figure 8) and push the member forming the riser forming surface (13) against the resistant edge (18).

Present also is an adjustable stop (35) and its adjustment means as a back stop adjuster (36). The adjustable stop (35) butts up against the backside of the riser forming surface (13) to prevent its movement inward (to the right when viewed in Figure 8). Therefore the nosing (33) of one thread relative to another can be adjusted by relative positioning of the backstop (35). In the particular embodiment shown the backstop (35) is a rectangular hollow section that is supported by a threaded back stop adjuster (36) as shown in Figure 8. The back stop adjuster (36) consists of a threaded rod that is thread wise engaged with a nut that sits on the upside of a return surface of the tread forming surface (11) as shown. Winding the thread will cause the back stop (35) to move up or down the tread forming surface (35). Therefore tightening of the nut against the return of the tread forming surface (11) pushes the adjustable stop (35) against the backside of the riser forming surface (13). Other means to effect this movement will be apparent to those skilled in the art. For example hydraulic, air or lever mechanisms may be used.

The backstop (35) runs for most of, and in the preferred embodiment all of, the width of the riser forming surface (13).

The sliding bracket of the lower edge bracket (43) and upper edge bracket (44) allows adjustment of the pitch of the resulting flight of stairs (2). Additionally it allows easy removal of forming units (7) by sliding off the frame members (5). Therefore if stairs need to be formed with only ten steps but a set of fourteen forming units (7), are

supplied, then four can be removed to form a ten step flight of stairs (2). If additional stairs also need to be added then additional forming units (7) can be added to increase the number of stairs in a flight of stairs (2).

A single forming unit (7) that defines upper tread forming surface (11) and riser forming surface (13) can be pivoted at or toward its lower edge (19) of the tread forming surface from a lower edge bracket (43) and pivoted from a distal edge (23) by an upper edge bracket (44) preferably distal edge (23) is parallel to the lower edge (19). As described each bracket can also slide on its respective frame member (5) and (5a). A bearing surface (25) is present on the lower most edge of the riser forming surface (13). This bearing surface (25) bears on the tread forming surface (11) of an adjacent forming unit (7). In the preferred embodiment this bearing surface (25) is a compressible material so that under compressive loading it will form a seal to resist the egress of any settable material between the riser forming surface (13) and the tread forming surface (11) on which it bears. Similarly there is a seal (16) at the interface between the upper most edge of the riser forming surface (13) and the distal edge (23). However in other embodiments no seal need be present.

When the side mould surface (20) is located within the width of the stair moulding apparatus (1) then adjustable side brackets (42) can extend from the frame (3) at regular intervals thereon to support the side mould surface (20). In the embodiment shown they extend from the right hand side of the frame (3). They could just as easily extend from the left hand side or from both sides.

When a landing (6), either at the head or bottom of the flight of stairs (2), is to be formed then landing surfaces (34) are located in place. These landing surfaces ((34a) for the bottom landing surface and (34b) for the head landing surface) are adjustable in angle relative to the frame. This is so that they can accommodate variable pitches of flights of stairs (2). The landing surfaces (34) form the upper presenting surface of the landing (6) for the flight of stairs (2) when oriented for use. Because the landings (6) must have some thickness, additional landing surfaces (46) are located parallel to (in the preferred embodiment) and above the landing surfaces (34). The additional landing surfaces (46) act to form a cavity or void to receive the settable material.

The frame (3) and forming units (7) are generally laid horizontally; therefore the forming surfaces for the landings (6) are at an angle thereto. The bottom landing forming surface (34a) angles downward, and the head landing forming surface (34b) angles upward, relative to the frame (3). Without these additional landing surfaces (46) the settle material could not easily be formed at an angle to the horizontal.

When using a settable material such as concrete or similar it is often vibrated into position to remove air that may be present. The weight of the settable material combined with this vibration action creates significant stress on parts of the apparatus. Additional reinforcing, in the form of structural beams (45) may be located wherever there is insufficient bending strength in any of the forming surfaces to counteract the weight of the settable material combined with the additional loading vibration to remove air pockets creates.

In Figure 3 the additional landing surfaces (46a) and (46b) have structural beams (45) located across their tops. These beams may attach by clamps (48) to the underside of the landing surfaces (34a) and (34b). Again the structural beams (45) in this instance are of rectangular hollow section of cross section to impart the required strength.

In the preferred embodiment die threaded member used is threaded reinforcing bar. This material is generally available in such manufacturing operations, settable material normally easily breaks off it, and if damaged at all die threaded member can easily and cheaply be replaced.

At die very end of the bottom landing forming cavity (comprised of bottom landing surface (34a), side moulding surfaces (20) and additional landing surface (46a)) is located a cavity closing surface (50). This ensures diat die cavity for forming the bottom landing is only open upwards towards the main part of the stair forming apparatus (1).

The method of use of the apparatus will now be described. The lower edge brackets (43) and upper edge brackets (44) as earlier described are slidably engaged to the frame members (5).

In use the desired stair pitch (i.e. spacing along the pitch line of the stairs of one stair nose to the next stair nose is set up by sliding the forming units (7) to the required pitch distance. This can be done in several ways. The profiled side mould surface (20)

when cut to the correct pitch shape can be used as a guide to set the forming unit (7) pitch. In other ways it can be measured by hand, or a set up jig can be used, or other measuring means on the frame (3) can be used.

The approximate pitch of the forming units (7) is then set. The incline angle (15) of the tread forming surface (11) to the- frame (3) is then set globally for the steps (4) in the flight of stairs (2). In the preferred embodiment this incline angle (15) is initially set to the approximate angle. This can be done in one of several ways. First the relative height of the adjustable frame member (5a), in this case to the frame member (5b) above it, can be adjusted in the way described. This sets the relative angle (15) of the forming units. As the adjustable frame member (5a) is raised it reduces the relative incline angle (15) of the. tread forming surface (11) the frame members (5) that in this case lie parallel to the horizontal direction. As the adjustable frame member is lowered the opposite occurs. In other embodiments it may be the frame member that is pivotally and slidably attached to the upper edge (23) that may be adjustable. In this case the opposite movements cause increase and decrease of the relative angle (15). A person skilled in the art will understand such equivalence.

In other ways for example if the distal edge (25) of the tread forming surface (11) is not pivotally connected to a frame member it can be set by the relative height of the riser forming surfaces (13). In further alternatives the lower edge may be simply supported. This simple support may move up and down to effect change in the incline angle (15). Alternatively the simple support may be stationary, at least in the vertical direction and the upper edge (23) may be adjustable, as described to change the incline angle (15). Other equivalents will be apparent to a person skilled in the art.

Once the stair pitch and relative angle are approximately set for the tread forming surface (11) if not already in place the riser forming surfaces (13) are located therein. In the preferred embodiment the riser forming surfaces (13) are located in place after the approximate angle of the tread forming surfaces (11) are set. The subsequent setting of the correct angle of the tread forming surfaces (11) then clamps the riser forming surfaces (13) in place. These bear upon a resistant edge (18) located at the interface of the riser forming surface (13) with the distal edge (23) of one tread falling surface and the resistant edge (18) and the adjustable stop (35) of the adjacent tread

forming surface (11). If required the nosing (33) is set for each of the riser forming surfaces (13) by adjusting the adjustable stop (35) by changing its backstop adjuster (36) as previously described. Thereafter if not already in place the side mould surfaces (20) are located on the forming surface (9). If required the lower, upper and side surfaces for forming the landing or platform (6) are then also located at the head (38) or bottom (40) or both and angled at the desired inclination.

Thus the stair forming apparatus (1) can adjust the number of stairs (4) to be formed, the height of the stair riser (14), the depth of the tread (12), including any overlap or nosing (33), the width of die stairs, the angle of the stairs and if present the size of any landing (6)

Where extra bracing of any forming surface is required these can then be put in place.

If any reinforcing (58) for the flight of stairs is required (2) this is then located into the stair moulding apparatus cavity that is now formed. Thereafter settable material (31) is located in die cavity and may be vibrated into place. Once the bottom landing cavity has been filled and the main stair cavity has been filled then the additional landing surface (46b) for the head landing (if present and required) is located in the place and setde material is located in that final void. Thereafter a cavity closing surface (50b) is located to close of the head landing cavity. If required any lifting rings or connections points are located in the settable material before it cures. Alternatively these may be attached to any reinforcing prior to pouring of the settable material.

Once the settable material has set the resulting form from the stair moulding apparatus (1) can be removed. In order to do this it is preferable if some of the forming surfaces are loosened from the cured settable material. The side mould surfaces (20) can be freed in the following way. The side brackets (42), whether adjustable or not, are held in place by a bracket wedge (54). This holds the side mould surfaces in place. When the bracket wedge is not present there is a degree of lateral play (e.g. 10 — 15 mm) transverse to the mould. However after die settable material has cured the side mould surface (20) has very likely adhered to the cured material. When the wedge is removed, reversed and located back into place a sharp tap of the

bracket wedge will drive the side brackets (42) away from the cured settable material. This will in turn break the adhesion between the cured settable material and the side mould surface.

The tread forming surfaces (11) and riser forming surfaces (13) can also be moved relative to the cured settable material to help release the flight of stairs. The adjustable stops can be loosened and /or the tread forming surfaces moved away from the tread surfaces of the stair flight they have formed.

If further forming surfaces need to be freed from the cured settable material that can be done by tapping with a hammer or other ways known in the art. Also the stair moulding apparatus may be actuated to rack it away from the cured settable material.

A further embodiment of the present invention will now be described with reference to Figures 17 through 28. This embodiment also allows many different stair configurations to be made, all off the same apparatus.

A flexible membrane (71) provides a supported flexible forming surface (9). The flexible membrane (71) in one embodiment can be in the form of a flexible belt. The flexible membrane (71) can be one long continuous belt or made up of shorter individual sections.

The flexible membrane is laid over adjustable formers (73) and clamped and held in position by adjustable belt clamps (79). The adjustable clamps (79) can be adjusted so the desired size and shape of the individual steps is attained. The adjustment of the two adjustable belt clamps (79) is by vertical separation. This will vary the angle of the treads of the step, as well as the tread depth and riser height.

The adjustable clamps (79) are in turn supported by side frames on either side.

The flexible membrane (71) can be tensioned so the required shape is held during casting. The tensioning can, in one embodiment, be achieved by adjustable tensioners (81). These lie below the interface of two adjustable formers (73). In particular this interface would be the nose of the step that is to be formed. The adjustable tensioners (81) can be adjusted separately or in unison. For example they may be located on a further movable side frame that pulls them down to tension the flexible membrane (71). There may also be additional minor tensioning present, such as provided by

turnbuckles between the adjustable tensioner and the belt tensioning bolt (70) pulling the flexible membrane (71).

The adjustable formers (73), adjustable belt clamps (79) and tensioning devices (81) can all be adjusted to change the length, height and any other angle required. As one preferred option a frame (3) can hold side rail frame members (5) that support the formers, clamps and tensional assemblies. The sides (20) of the mould surface can be adjusted to change the width of the mould and therefore the width of the flight of stairs that can be formed in the mould. The side mould surfaces (20) can be made from wood or any other suitable material. Sections of the flexible belt (71) can be added or removed if more or less length is required, to form as many treads as required.

The adjustable formers (73), adjustable belt clamps (79), adjustable belt tension adjusters (81) can be designed in many different configurations so long as they create the desired step profile from which a step for a flight of stairs can be moulded. In one embodiment there can be an adjustable tensioner (81) for each section of flexible membrane (71) or one adjustable tensioner (81) to join two sections of flexible membrane (71). In other words the flexible membrane (71) can span to form several forming surfaces (9), or it can extend up from one adjustable tensioner (81) over an adjustable former (73) and down to finish at the next adjacent adjustable tensioner (81).

The adjustable tensioner (81) can be clamped to the bottom rail or bottom frame member (5A) of the frame (3) or can catch on the bottom frame member (5A) in the appropriate position. The flexible membrane (71) can be made from any material that can be formed to the desired shape. The frame members (5) can be flat bar, round or any other shape that can hold the adjustable formers (73), adjustable belt clamps (79), and adjustable tensioners (81) in the desired configuration for the belt or flexible membrane (71). The adjustable side bracket (42) for holding the side mould surface (20) in one embodiment has wedges and slots to hold and move the sides (20) when required. The adjustable side brackets (42) can also be made to pivot out of the way. One or both sides of these adjustable side brackets (42) can be adjustable to change the width of the mould.

The figures show two pairs of rail sections or frames (3) but more can be added as required to give the required length.

The adjustable belt clamp (79) engages on the middle rail (5B) of the frame (5). The middle rail (5B) can be adjusted up and down to change the step profile. The middle rail (5B) mounted: adjustable belt clamp (79) or former clamp forms both the shape of the flexible membrane (71) and also clamps the two sections of flexible membrane (71) together, thus forming the desired shape. The end former section (72) can be designed to create any shape the stair profile requires. The top and bottom rails (5C) and (5A) respectively of the frame (5) are shown as being fixed but these can also be made to be adjustable if so desired.

The belt support or adjustable former (73) can be made so they can be adjusted to minimise the amount of gap created under the flexible membrane (71). The adjustable formers (73) do not have to be used in all circumstances as more tension on the belt can be supplied if required to take the weight of the settable material. The adjustable formers (73) are designed to minimise the tension required to achieve the form required.

Figures 27 and 28 show how the sides of the adjustable formers (73) are made so they sit on the Top Former and the Middle Former-Clamp, this means they are automatically set to the correct position as the step profiles change. A seal or sealing compound can be fitted to the side mould surfaces (20) between it and the flexible membrane (71) along the step profile to stop any concrete from leaking. A seal or sealing compound can be used to seal along the join created by the Middle Former-Risers.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.