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(11) | EP 3 970 930 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | FORMWORK FOR CONCRETING PREFABRICATED STAIRS AND METHOD FOR ITS MANUFACTURE |
| (57) The invention relates to a cardboard formwork (100) for concreting a prefabricated
stair (140), wherein concrete is being poured into the cardboard formwork (100) during
concreting, and wherein the cardboard formwork (100) is constructed by folding and/or
assembling one or more cardboard elements (110), and the one or more cardboard elements
(110) are cut with predetermined cuts (120) and/or cutouts (130), and wherein the
assembled cardboard element(s) (110) facing the concrete constitute a substantial
part of the formwork (100), the formwork (100) being capable of supporting the prefabricated
stair (140) during the process of concreting said stair (140).
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FIELD OF THE INVENTION
[0001] The present invention relates to a stair formwork made of cardboard and a method for concreting a prefabricated stair. In particular, it relates to a stair cardboard formwork and method, wherein concrete is being poured into the cardboard formwork during concreting, and wherein the cardboard formwork is constructed by folding and/or assembling one or more cardboard elements, and the one or more cardboard elements are cut with predetermined cuts and/or cutouts. The invention also relates to a corresponding computer program for implementing the method.
BACKGROUND OF THE INVENTION
[0002] Within the area of concreting parts of houses and buildings, in particular concreting stairs, it is necessary to use formworks, i.e. a form or a mould, in place to hold in wet concrete until the concrete hardens and sets in the forms.
[0003] In the field of concreting parts of houses and buildings, there is a need of a large number of formworks to define the house parts, such as stairs. The formworks are conventionally manufactured on the concreting site in wood or timber boards, and sometimes even metal moulds are manufactured if special considerations applies, i.e. larger number of products, a higher need for precision or higher load on the sides of the formwork. Normally the formworks are made in wood boards, and the forms are applicable only for a relatively smaller number of concrete products. Furthermore, the formwork is often a unique specimen to the specific order of a concrete house part, especially when it comes to stairs. This means that subsequent to the concreting no or only little reuse can be made of the formworks, which are then discarded as an industrial waste product from the concrete construction.
[0004] Particularly when it comes to formworks for concreting stairs a need of very specific and unique formworks is identified and in addition, the formworks have to be of an extremely detailed execution as a stair is a complex form due to the many steps, corners, etc.
[0005] The use of wood material for producing a stair formwork and the manual construction is both time consuming and rather demanding with respect to dedicated skilled personnel. Additionally, wood formworks, especially large formworks as formworks for stairs, have a heavy weight and thereby a heavy and troublesome load for the skilled person to handle. It also requires storage room for the formworks before and after use for concreting. Furthermore, the wood material is a significant industrial waste production from the concreting process.
[0006] Hence, an improved formwork for concreting stairs would be advantageous, and in particular a more efficient, economically and/or reliable formwork for the concreting industry would be advantageous.
OBJECT OF THE INVENTION
[0008] In particular, it may be seen as an object of the present invention to provide a formwork for prefabricated stairs that solves the above mentioned problems of the prior art disclosing the use of manually constructed formworks, typically in wood.
SUMMARY OF THE INVENTION
[0009] Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a cardboard formwork for concreting a prefabricated stair, wherein concrete is being poured into the cardboard formwork during concreting, and wherein:
- the cardboard formwork is constructed by folding and/or assembling one or more cardboard elements, and
- the one or more cardboard elements are cut with predetermined cuts and/or cutouts, and
[0010] The invention is particularly, but not exclusively, advantageous for obtaining an improved and simplified formwork for concreting stairs. Particularly, the use of cardboard instead of wood, normally used in this field, has a significantly simplified manufacturing, lowering production time, improving the working environment due to lower weight and improving the financial expenses of a formwork for concreting a stair.
Furthermore, the invention is particularly, but not exclusively, advantageous for being more environmentally friendly because cardboard can normally be recycled more easily than wood or metal. The cardboard formwork of the invention is a very sustainable variant of a formwork for stairs, as the formwork is exceptionally environmentally friendly compared to prior known stair formworks.
The cardboard of the formwork is preferably made of recyclable cardboard capable of being recycled after concreting as defined by appropriate waste standards, formal or de-facto standards, optionally after light or moderate cleaning/removal of concrete remnant material from the casting. Additionally or alternatively, the cardboard itself is made of recycled material from recycled paper or cardboard to lower the environmental footprint of the invention.
[0011] In the context of the present invention, a 'stair' may be understood to have a stair-like structure and shape, as the skilled person or engineer in building construction will readily understand. In particular, it is to be understood that a stair in the context of the invention is defined as having a plurality of steps - thereby a minimum of two steps.
[0012] In the context of the present invention, a 'prefabricated concrete stair' may be understood as a stair made of concrete and which is fabricated off-site, that being in contrary to stairs being fabricated on site.
[0013] In the context of the present invention, a 'cut' in the cardboard elements may be understood as preferably straight cut into the cardboard, the cut being in any preferred angle, wherein nothing from the cardboard element should be removed after the cut. That being contrary to the cutout defined below.
[0014] In the context of the present invention, a 'cutout' may be defined by a plurality of cuts made into the cardboard so as to facilitate a removal of a piece of the cardboard element after the cutout is prepared. Thus, a cutout may generally be defined as a shape that has been cut out from a material, in the present invention the material being cardboard.
[0015] In the context of the present invention, 'facing' may be understood as a synonym to e.g. fronting or abutting. Meaning that the cardboard elements facing the concrete constitute the part of the cardboard formwork, which during concreting is in contact with the concrete.
[0016] In the context of the present invention, a 'substantial part' may be understood as the most of or the majority of the formwork - Meaning that e.g. 70%, 80%, 90% or preferably 95% to 100% of the formwork is made of cardboard.
[0017] In the context of the present invention, 'cardboard' may be understood to mean heavy-duty paper of various strengths and thicknesses, in particular the cardboard is understood as comprising sandwich-elements i.e. a composite structural paper material having layers of cardboard facing each other, for example for obtaining higher strength and/or improved humidity repellent properties for concrete casting or moulding, the layers of cardboard may be oriented in various directions relative to the surface of the cardboard, e.g. parallel to the surface or orthogonal to the surface, or combinations thereof. In particular, a part of the cardboard sandwich-element may have a fluted core, and/or it may have one or more corrugated layers.
[0018] Preferably, the cardboard sandwich-element may have an in-plane and out-of-plane compressive strength of at least 10, 15 or 20 kN/m and/or at least 300, 500, 700 kN/m, respectively, to provide sufficient strength for the formwork during the entire casting process, e.g. several hours of casting. Thus, the casting process may last at least 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 20 hours, 30 hours, 40 hours, 2-7 days, or even longer. Preferably, the cardboard sandwich-element may have a total thickness of at least 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20 mm, or thicker, to provide sufficient thickness for the formwork during the casting process.
[0019] Alternatively or additionally, the cardboard sandwich-element may have a humidity repellent surface layer, such as a wax or polymer-coating, facing the concrete stair during casting, or molding, so as to repel or prevent any liquids from the concrete to moisture, or wet, the cardboard formwork during casting, which may negatively influence the strength and durability of the cardboard formwork. It is known within the field of cardboards to define a so-called wet strength including the ability to withstand humid or wet conditions; the wet strength may be increased by appropriate wet strength adhesives for cardboards, such as water resistant adhesives, e.g. glues, paste, or mucilage. The humidity repellent surface layer is preferably chosen for being subsequently recyclable together with the cardboard. Alternatively, the humidity repellent surface layer may be, at least partly, removed prior to recycling of the cardboard formwork.
[0020] In an embodiment of the invention, the formwork facing the concrete during concreting of the stair is made entirely of cardboard.
The embodiment is particularly, but not exclusively, advantageous for providing a stair formwork with the exact desired stair design. Many unique designs of concrete stairs are often very advanced to produce in a wood formwork, as the design might have several different proportion and special needs that cannot be made by wood formwork or is very challenging and consuming and demanding to produce. By producing the part of the formwork facing the stair entirely in cardboard, it provides a formwork being able to produce more or less every design a customer potentially wants of their stair, as cardboard is a lot easy to form in any desired design.
Preferably, the entire formwork is made of cardboard, though in an embodiment of the invention, the substantial part of the formwork is made of cardboard and minor parts are made in other material e.g. some reinforcement part on the outer side of the formwork is made of wood and/or metal. The 'outer side' of the formwork being the part of the formwork not facing the concrete during concreting.
[0021] In an embodiment of the invention, the part of the formwork intended for forming the steps during concreting of the stair is made entirely of cardboard.
The embodiment is particularly, but not exclusively, advantageous for providing a stair formwork with the exact desired step design. The steps of the concrete stairs often being the ones most advanced to produce in a formwork, as the steps might have several different proportion and special needs.
[0022] In an embodiment of the invention, the stair being concreted in the cardboard formwork is a freestanding stair.
The embodiment is particularly, but not exclusively, advantageous for possibly providing a stair with a lot lower quantity of concrete needed compared to a fully supported stair from beneath, and thereby providing a stair with a lot lower weight and a lot easier to handle.
[0023] In the context of the present invention, 'freestanding stair" may be understood to mean a concreted stair only being supported from below at the two ends of the stair when mounted in a building.
[0024] In an embodiment of the invention, the assembling of the cut cardboard elements is made as a puzzle-assembly, wherein a cutout of a first cardboard element is fitting a cutout of a corresponding second cardboard element. The embodiment is particularly, but not exclusively, advantageous for providing an easy and rapid, but still sufficient and durable, assembly of the cardboard elements of the formwork for concreting a stair.
[0025] In the context of the present invention, a 'puzzle-assembly' may be understood as an assembly wherein two (or more) pieces of cardboard due to their matching cut and/or cutouts are fitting substantially together, preferably fitting ideally, when assembled, so as to form two (or more) interlocking cardboard elements. This means that two adjacent elements are connected in such a way that the elements is locked in at least one direction. One embodiment of an interlocking puzzle-assembly of cardboard elements could e.g. be when a first element is cut to form a protruding part on one of its sides and a corresponding second cardboard element is cut with an inward part of one of it sides, the protrusion and the inward part engaging and fitting substantially together, preferably fitting ideally, to each other.
One cardboard element can fit with a plurality of other cardboard elements, as an interlocking puzzle-assembly can be made of any side of a cardboard element. E.g. if a cardboard element is cut in a shape having four sides, the cardboard element potentially being able to interlock with 4 other cardboard elements.
[0026] In an embodiment of the invention, the assembly of the cardboard elements is made by fixing a cardboard element between at least two other cardboard elements via tension.
The embodiment is particularly, but not exclusively, advantageous for providing an easy and rapid, but still sufficient and durable, assembly of the cardboard elements of the formwork for concreting a stair.
Furthermore, the embodiment is advantageous as the assembly of two cardboards via tension provide an assembly without the need of at least to fitting cut and/or cutouts as when e.g. a puzzle-assembly is prepared.
[0027] In an embodiment of the invention, the assembly of the cardboard elements is made by fixing a cardboard element between at least two other non-cardboard elements via tension.
The embodiment is particularly, but not exclusively, advantageous for providing a even stronger cardboard formwork.
[0028] In an embodiment of the invention, the assembling of the cardboard elements is made by inserting at least a first cardboard element into at least a second other cardboard element. The at least two corresponding cardboard elements being cut to allow an insertion, wherein the insertion performs a function of an assembly.
[0029] In an embodiment of the invention, the cardboard formwork comprises:
- at least one step-piece for forming the steps of the stair being concreted, the step-piece comprising at least one cut cardboard element,
- at least one fixing-piece, preferably two, for fixing the at least one step-piece into a desired step-form, the fixing-piece comprising at least one cut cardboard element, the at least one fixing-piece is being assembled with the at least one step-piece, and
- at least one side-piece for forming the sides of the stair being concreted, the side-piece comprising at least one cut cardboard element.
Furthermore, the embodiment is particularly, but not exclusively, advantageous for providing a stair formwork wherein the at least three main parts of the formwork can easily be changed if any unique design of the stair is demanded. The three pieces can easily be cut in different dimensions, different shapes with different cut and/or cutouts and still be assembled to form a formwork for concreting a stair. This provides a stair formwork that very easily can adopt the exact design of a stair, which a customer might demand.
Additionally, the embodiment is particularly, but not exclusively, advantageous for providing a formwork, which is overall made of three main parts, wherein the three parts are very easy to handle when assembling the formwork.
[0030] In an embodiment of the invention, the formwork comprises a baseplate, wherein the formwork is assembled by inserting one or more cardboard pieces of the formwork into the baseplate for stabilizing and supporting the cardboard formwork, the baseplate preferably being positioned at the bottom of the cardboard formwork.
The embodiment is particularly, but not exclusively, advantageous for proving a stair formwork that easily can be manufactured suitable for concreting a large stair construction, which often would need some kind of a reinforcing supporting element. By inserting a baseplate as an extra supporting element at the bottom of the formwork, the formwork provides an even stronger formwork and thereby allowing the stair, which has large dimensions, to be concreted in the formwork.
[0031] Furthermore, the embodiment is particularly, but not exclusively, advantageous for proving a stair formwork that is stabilized in a unique manner, as the baseplate provide an extra support and stabilizing effect to the formwork.
Additionally, the embodiment is particularly, but not exclusively, advantageous for proving a stair formwork being easily assembled on the baseplate.
[0032] In an embodiment of the invention, the cardboard formwork comprises one or more of cardboard support-elements assembled to the base-plate. The embodiment is particularly, but not exclusively, advantageous for providing extra support and stability to the the formwork.
[0033] In an embodiment of the invention, the cardboard formwork comprises one or more through-going cardboard elements, the one or more through-going cardboard elements preferably being attached to the side-pieces. The embodiment is particularly, but not exclusively, advantageous for providing an even better stabilization and support of the formwork.
[0034] In an embodiment of the invention, the formwork during concreting is constructed with reinforcement plates on one or more of the sides of the formwork, the plates possibly being made of other materials than cardboard, and wherein the reinforcement plates are interconnected via at least one through-going threaded rod.
The embodiment is particularly, but not exclusively, advantageous for proving a stair formwork that easily can be manufactured suitable for concreting large stair constructions, which often would need some kind of a reinforcing support element. The reinforcement elements are providing an extra support at the sides of the formwork and thereby providing an even stronger formwork allowing the stair having large dimensions to be concreted in the formwork.
Furthermore, the embodiment is particularly, but not exclusively, advantageous for proving a stair formwork that is stabilized in a unique manner, as the interconnection of the reinforcement plates via at least one through-going threaded rod provide an extra support and stabilizing effect to the formwork.
[0035] In an embodiment of the invention, the cardboard formwork is providing a prefabricated concrete stair having one or more rounded front edges, the rounded front edges being constructed by folding cardboard elements with custom made cuts, so that the cardboard element can form a curvature at the one or more rounded front edges.
The embodiment is particularly, but not exclusively, advantageous for providing a cardboard formwork that provides a concreted stair with rounded front edges, which is a huge demand today - Up to about 90% of the costumers request stairs having rounded front edges. Having rounded front edges on a stair leads to the advantage that the stair steps are in the most comfortable shape as possible. A stair with sharp edges have the disadvantage of potentially hurting e.g. the food or the shin of a person who by accident bumps into the step edge.
Also the rounded front edges provide an aesthetic advantage to the stair.
[0036] In the context of the present invention, rounded edges' may be understood as edges, which is facing the person walking on the stair, having some kind of rounded form. The rounded form being in contrast to an angular edge, which is often in a rectangular form. The form of the rounded edges can potentially be made in any desired rounded form and with any desired radius of the rounding at the edge of the stair.
[0037] In an embodiment of the invention, the curvature of the one or more rounded front edges are made with a predetermined radius, the radius being determined by at least:
- the number of cuts,
- the angle of the cuts, and
- the placement of the cuts on the cardboard element forming the rounded front edges.
[0038] In an embodiment of the invention the number of cuts prepared into the cardboard are in the range of 1-30, preferably in the range of 2-20, most preferably in the range of 6-12.
[0039] In an embodiment of the invention, the cuts prepared into the cardboard are made as 20-10mm cut, preferably 12-18mm cut, most preferably 14-16 mm cut.
In an embodiment of the invention, the cuts prepared into the cardboard are made in the cardboard only leaving ½-5 mm of the bottom of the cardboard not being cut through.
The embodiment is particularly, but not exclusively, advantageous for proving a rather specific dimension of the cut into the cardboard. The cut dimension having an operative effect one the cardboard to be folded to form the rounded edge of the stair.
[0040] In an embodiment of the invention, the cut are made with an angle in the range of 30-120 degree, preferably in the range of 40-100 degree, most preferably in the range of 45-90 degree.
[0041] In an embodiment of the invention, the cuts for forming a curvature are made with a distance from the centre of the curvature. The embodiment is particularly, but not exclusively, advantageous for providing an optimal technique of cutting a cardboard to be folded to form a curvature.
[0042] In an embodiment of the invention, the cardboard formwork is providing a stair having one or more string coves. In the context of the present invention, 'string cove' may be understood as one or more of the side edges of the steps having some kind of protrusion. A synonym of a string cove might be a "protruding edge", a "washing edge", a "water stopping edge" or other relevant alternative designations.
The embodiment is particularly, but not exclusively, advantageous for providing a cardboard formwork that provides a concreted stair with string coves on the steps, which is a huge demand today - Up to about 80-90% of the costumers request stairs having string coves. Having string coves on the steps of the stair leads to the advantages that the stair steps can easily be washed without the soap and water flushes over the side edges. The water is kept on the steps within the string coves due to the protrusion of the string coves.
[0043] In an embodiment of the invention, a plurality of step-pieces are comprised in the formwork, wherein the step-pieces is being assembled together, preferably by puzzle-assembly.
The embodiment is particularly, but not exclusively, advantageous for providing the possibility of forming a cardboard formwork for concreting a relatively large stair comprising many steps. The more step of the stair, the more cardboard step-pieces might be needed to form the formwork.
[0044] In an embodiment of the invention, wherein the one or more string coves are constructed by introducing at least one string-cove-piece into the cardboard formwork, the string-cove-piece being an elongated cut cardboard element positioned between a side-piece cardboard element and a step-piece cardboard element of the cardboard formwork. The embodiment is particularly, but not exclusively, advantageous for proving an effective and easy construction of a formwork, which can provide a concreted stair with string coves.
The embodiment is particularly, but not exclusively, advantageous for proving one or more additional pieces of the cardboard formwork e.g. the string-cove-pieces, which are optional pieces - meaning that the cardboard formwork can easily be produced to include one or more string-cove-pieces, if one or more string coves is desired on the stair. If a string cove is not desired on the stair, the formwork can also easily be produced without the additional pieces.
Furthermore, the embodiment is particularly, but not exclusively, advantageous for proving one or more additional pieces, which easily can be customized depending on the desired dimension of the string-coves on the stair. As the one or more string-cove-pieces are elongated cut cardboard elements, preferably without any protrusions or any inward parts, the additional elongated string-cove-piece is very easy to produce in any desired dimension. The string-cove-piece is preferably also being cut to provide a string-cove with rounded edges.
[0045] In an embodiment of the invention, the at least one string-cove-piece is inserted into an adapted cutout of the side-piece element and being adjacent to the step-piece element.
The embodiment is particularly, but not exclusively, advantageous for providing a very easy but effective assembly of a cardboard formwork with a string-cove-piece, as the string-cove-piece is straightforwardly inserted into the adapted cutout of a side-piece cardboard element. This assembly being straightforward but in the same time being a very effectively and strong attachment.
[0046] In a second aspect, the present invention relates to a method for manufacturing a cardboard formwork for concreting a prefabricated stair, preferably concreting the stair in one piece, the method comprising:
- providing one or more cardboard elements,
- performing a cutting with a cutting apparatus of one or more cuts and/or cutouts in the one or more cardboard elements,
- forming a formwork by
- folding the one or more cut cardboard elements at the one or more cut and/or cutouts, and/or
- assembling the cut cardboard elements, which are being cut to fit each other, and
[0047] The present invention according to the second aspect is particularly, but not exclusively, advantageous for providing a method that may significantly lower production time, improve the working environment due to lower weight and is more environmentally friendly because cardboard can normally be recycled more easily than wood, or metal.
[0048] In an embodiment of the invention relates to a method for manufacturing the cardboard formwork, wherein the cardboard formwork is assembled as a puzzle, where cuts and/or cutouts of first cardboard element is fitting a cut and/or cutout of a second corresponding cardboard element, and wherein the first cardboard elements can be cut to be assembled with a corresponding second cardboard element.
The embodiment is particularly, but not exclusively, advantageous for providing an easy and rapid, but still sufficient and durable, method of assembling of the cardboard elements of the formwork for concreting a stair.
[0049] In an embodiment of the invention relates to a method for manufacturing the cardboard formwork, wherein the cardboard formwork is assembled by fixing a cardboard element between at least two other elements via tension.
The embodiment is particularly, but not exclusively, advantageous for providing an easy and rapid, but still sufficient and durable, method of assembling of the cardboard elements of the formwork for concreting a stair.
Furthermore, the embodiment is advantageous as the method of assembling of cardboard formwork via tension provide an assembly without the need of at least to substantially fitting cut and/or cutouts as when e.g. a puzzle-assembly is prepared.
[0050] In a third aspect, the present invention relates to a computer program being adapted to enable a computer system comprising at least one computer having data storage means in connection therewith to control a cutting apparatus, or cutting system, for cutting cardboard formwork according to the second aspect. Thus, the computer program product, e.g. in the form of computer-aided drawings (CAD) with the appropriate instructions for cuts and cutouts, may enable a cutting apparatus to implement, at least partly, the invention according to the second aspect, the folding and assembling of the formwork preferably being subsequently performed manually by an operator/technician, and/or by a robotic device.
[0051] The individual aspects of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from the following description with reference to the described embodiments.
BRIEF DESCRIPTION OF THE FIGURES
[0052] The invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.
Figure 1 schematically shows a cardboard formwork for concreting a stair.
Figure 2 schematically shows two fixing-pieces of a cardboard formwork for concreting a stair.
Figure 3 schematically shows a folded step-piece of a cardboard formwork for concreting a stair.
Figure 4 schematically shows a top-view of a step-piece of a cardboard formwork for concreting a stair.
Figure 5 schematically shows a string-cove-piece of a cardboard formwork for concreting a stair.
Figure 6 schematically shows a side-piece of a cardboard formwork for concreting a stair.
Figure 7 shows a cardboard formwork for concreting a stair comprising a base-plate.
Figure 8 shows a cardboard formwork filled with wet concrete and comprising reinforcement plates being interconnected via through-going threaded rods.
Figure 9 shows a flow-chart of a method according to the invention for a method for forming a cardboard formwork for a stair.
Figure 10 schematically shows a prefabricated stair concreted in a cardboard formwork.
Figure 11 shows a prefabricated stair concreted in a cardboard formwork.
DETAILED DESCRIPTION OF AN EMBODIMENT
[0053] In the following, the present invention will be described in detail in connection with a preferred embodiment thereof with references to the accompanying figures.
[0054] FIG. 1 schematically shows a formwork 100 according to a presently preferred embodiment of the invention. The cardboard formwork is used for concreting a prefabricated stair, wherein concrete is being poured into the cardboard formwork during concreting, and wherein the cardboard formwork is constructed by folding and/or assembling one or more cardboard elements 110, and the one or more cardboard elements are cut with predetermined cuts 120 and/or cutouts 130 (not shown). Furthermore, the assembled cardboard element(s) facing the concrete constitute a substantial part of the formwork, the formwork being capable of supporting the prefabricated stair during the process of concreting said stair.
[0055] Moreover, FIG. 1 schematically shows a present preferred embodiment of the invention, wherein the cardboard formwork 100 comprises one step-piece 160 forming the steps of the stair being concreted and two fixing-pieces 170 (only one is visible) fixing the at least one step-piece into a desired step-form and wherein the two fixing-pieces is assembled with the step-piece using puzzle-assembly 150, wherein cutouts 130 (shown in fig. 4) of the step-piece are fitting the cutouts of the corresponding fixing pieces. Furthermore, the formwork in Figure 1 comprises a side-piece 180 for forming a side of the stair being concreted. In the preferred embodiment of the invention a second side-piece (not shown) is provided on the out-fronting side of the formwork in Figure 1 for forming a second side of the stair being concreted. Also the preferred embodiment illustrated in Figure 1 comprises a string-cove-piece 240 for providing a stair having one or more string-coves 144 (shown in figure 10). The string-cove-piece being an elongated cut cardboard element positioned between a side-piece 180 cardboard element and a step-piece 160 cardboard element of the cardboard formwork, and wherein the string-cove-piece is inserted into an adapted cutout 181 (shown in FIG. 6) of the side-piece element and being adjacent to the step-piece element. Beneath the adjoining of the step-piece and the string-cove-piece a support might be provided (not shown). In the cardboard formwork illustrated in Figure 1, the concrete to be poured into the formwork will thereby be facing the part of the step-piece and side-piece so as to form - by the reverse forming process - a stair with string-coves 144 (shown in figure 10).
[0056] Additionally the cardboard formwork illustrated in Figure 1 is suitable for providing a prefabricated concrete stair having one or more rounded front edges 143 (shown in fig. 10) being constructed by folding the cardboard elements 110 with custom made cuts 120 (shown in fig. 4), so that the cardboard element can form a curvature 230 for forming the one or more rounded front edges of the stair being concreted. The curvature of the one or more rounded front edges are made with a predetermined radius and the radius is determined by at least: the number of cuts 120 (shown in fig. 4), the angle of the cuts, and the placement of the cuts on the cardboard element 110 forming the rounded front edges.
[0057] FIG 2 schematically shows two fixing-pieces 170 of a cardboard formwork for concreting a stair. The two illustrated fixing-pieces are suitable for fixing at least one step-piece 160 (shown in fig. 1) into a desired step-form. The two fixing-pieces illustrated is each made of one cut cardboard element 110 and the cardboard is cut to provide a puzzle-assembly 150 with a step-piece 160 (shown in fig. 1). The shape and design of the puzzle-assembly cutouts can be made in several different shapes and designs. The invention is not limited to the specific design illustrated in Figure 2, which is just one of many different cutouts of the fixing-pieces 170. The one or more cutouts 151, 152 and their corresponding fitting parts may together collectively form a puzzle-assembly 150 (shown in fig. 1).The cutouts for puzzle-assembly in the illustrated fixing-pieces are made with two relatively large protruding parts 151 and furthermore a plurality of relatively smaller protruding parts 152. Depending on the size of the stair to be concreted in the form, the fixing-pieces could have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10-15, 15-20 or even more relatively large protruding parts 151, if the stair being concreting has large dimensions and thereby need larger fixing-pieces. In addition, the number of smaller protruding parts 152 also depends on the size of the stair to be concreted in the formwork.
When assembling a cardboard formwork with a puzzle-assembly, the protruding parts both the relatively larger and the relatively smaller are all cut in a very specific shape so as to fit substantially with the cutouts (shown in fig. 4) of the corresponding step-piece (shown in fig. 1), and so they have the strongest possible fixing.
In other embodiments of the invention the fixing-pieces 170 is not necessarily made with cutouts for a puzzle-assembly, as any other preferred assembly e.g. via tension between at least two other elements or via an attachment made as an insertion of element into another, is also a possible embodiment.
[0058] FIG 3 schematically shows a step-piece 160 of a cardboard formwork 100 for concreting a stair when the step-piece is folded and ready to be assembled with the other parts of the formwork. The step-piece 160 illustrated is made of one cut cardboard element and the cardboard is cut to provide a puzzle-assembly 150 with at least one fixing-piece 170. The shape and design of the puzzle-assembly cutouts 130 can be made in several different shapes and designs. The invention is not limited to the specific design illustrated in Figure 3, which is just one of many different cutouts of the step-piece.
[0059] The cutouts for puzzle-assembly in the illustrated step-piece 160 are made with four relatively large protruding parts 151 on each side (only one side is illustrated). Depending on the size of the stair to be concreted in the formwork, the step-piece could have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10-15, 15-20 or even more relatively large protruding parts, if the stair being concreting has large dimensions and thereby need a larger step-piece. Also it could comprise relatively smaller protruding parts 152.
When assembling a cardboard formwork with a puzzle-assembly, the protruding parts are all cut in a very specific shape so as to fit substantially with the cutouts of the corresponding fixing-piece 170 (shown in fig. 1), and so they have the strongest possible fixing.
In other embodiments of the invention the step-piece 160 is not necessarily made with cutouts for a puzzle-assembly, as any other preferred assembly e.g. via tension between at least two other elements or via an attachment made as an insertion of element into another, is also a possibility.
[0060] Furthermore, FIG. 3 illustrates a step-piece 160 being cut so as to provide a formwork for a stair, which is to be concreted with rounded front-edges 143 (shown in fig. 10).
[0061] FIG. 4 schematically shows a top-view of a step-piece 160 of a cardboard formwork for concreting a stair, when the step-piece is not yet folded. The cutouts 130 made around the edges of the cardboard is in this illustrated embodiment made to be assembled via puzzle-assembly.
[0062] The cuts 120 made into the surface of the step-piece (illustrated with dotted lines) is cuts 120 into the cardboard, as no cardboard is removed after the cut.
The cuts are potentially performed in both a vertical direction (V) and a horizontal direction (H) of the cardboard, when seeing the cardboard from above as illustrated in Figure 4.
The horizontal H cuts 120 are made to form the rounded front edges of the stair 143 (shown in fig. 10). The cuts are performed with a specific number of cuts, with specific angles and with specific placements of the cuts into the cardboard element, to form the exact desired rounded front edges on the stair to be concreted in the formwork.
The vertical V cuts 120 is made to allow folding the side of the step-piece 160 to form a perpendicular folding and thereby allow the puzzle-assembly cutouts 130 on the sides of the step-piece to be assembled with corresponding fixing-pieces.
[0063] FIG. 5 schematically shows a string-cove-piece 240 of a cardboard formwork for concreting a stair having one or more string-coves 144 (shown in figure 10). The string-coves of the stair are constructed by introducing at least one string-cove-piece 240 into the cardboard formwork, and one embodiment of a string-cove-piece is illustrated in Figure 5. The string-cove-pieces in Figure 5 is an elongated cut cardboard element to be positioned between a side-piece 180 (shown in fig. 1) cardboard element and a step-piece 160 cardboard element of the cardboard formwork. The string-cove-piece illustrated is suitable for being inserted into an adapted cutout 181 (shown in fig. 6) of the side-piece element and being adjacent to the step-piece element.
[0064] Furthermore, FIG. 5 illustrates a string-cove-piece 240 being cut so as to provide a formwork for a stair, which is to be concreted with rounded front-edges 143 (shown in figure 10).
[0065] FIG. 6 schematically shows a side-piece 180 of a cardboard formwork for concreting a stair. The side-piece being for forming the sides of the stair being concreted, the side-piece 180 is made of at least one cut cardboard element. The side-pieces illustrated in Figure 6 is suitable for attachment and fixation of an elongated string-cove-pieces 240 (shown in fig. 5) by inserting the string-cove-piece into the adapted cutout 181 of the side-piece 180 element.
[0066] The side-piece 180 is suitable for being attached to a baseplate 190 (shown in fig. 7) of the formwork (not shown) either via assembly, via insertion or via tension between two other elements.
[0067] FIG. 7 illustrates a cardboard formwork of a cardboard formwork for concreting a stair comprising a base-plate 190, wherein the formwork is assembled by inserting one or more cardboard pieces of the formwork into the baseplate 190 for stabilizing and supporting the cardboard formwork, the baseplate preferably being positioned at the bottom of the cardboard formwork. Furthermore, Figure 7 illustrates a cardboard formwork comprising a plurality of cardboard support-elements 250 assembled to the base-plate, the support-elements are supporting and stabilizing the formwork during concreting.
Figure 7 illustrates five support-elements 250 attached to the base-plate 190, the number of support element are variable. A formwork with no, or with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more support-elements 250 is within the scope of the invention. Figure 7 furthermore illustrates the possibility of a cardboard formwork comprising through-going cardboard elements 260 attached to the side-pieces 180 and for providing an even better stabilization and support of the formwork. Only one through-going cardboard element 260 is also a possible variant of the invention. The through-going cardboard elements are preferably engaging with the cardboard support-elements 250.
In addition, it is illustrated in Figure 7 that the cardboard support-elements 250 are prepared to potentially allow a plurality of through-going treaded rods 210 (shown in fig. 8) to interconnect reinforcement plates via a plurality of holes made in the support elements.
[0068] FIG. 8 shows a cardboard formwork filled with wet concrete and comprising reinforcement plates 200 being interconnected via through-going threaded rods 210. The cardboard formwork illustrated in Figure 8 is a formwork comprising reinforcement plates 190 (shown in fig. 7) on two of the sides of the formwork, the plates possibly being made of other materials than cardboard, in Figure 8 they are made of wood. The reinforcement plates are interconnected via at least one through-going threaded rod 210, the embodiment illustrated in Figure 8 is interconnected via 8 through-going threaded rods 210. The number of through-going threaded rods vary depending on the size of the stair being concreted.
[0069] FIG. 9 shows a flow-chart of a method according to the invention for a method for forming a cardboard formwork 100 (shown in fig. 1) for a stair, the method comprises:
S1 Providing one, or more, cardboard element(s),
S2 Performing a cutting of one, or more, cuts and/or cutouts of the one or more cardboard element(s), and
S3 Forming a stair-shaped formwork by folding and/or assembling the one or more cut cardboard element(s).
[0070] The above method according to the invention may be performed in this order, or in another order, possibly one or more steps may be combined as the skilled person will readily understand.
[0071] FIG. 10 shows a prefabricated stair 140 concreted in a cardboard formwork 100 (shown in fig. 1). The stair illustrated is a preferred embodiment of a prefabricated stair having a plurality of steps 141, having string-coves 144 at two of the ends of the steps 141 and the steps is provided with rounded front-edges 143. Furthermore Figure 10 illustrate a stair suitable for being supported only at the two ends of the stair 140 when mounted in a building construction.
[0072] FIG. 11 shows a plurality of prefabricated stairs 140 concreted in a cardboard formwork 100 (shown in fig. 1). The stairs illustrated is a preferred embodiment of prefabricated stairs having a plurality of steps 141, having string-coves 144 at two of the ends of the steps 141 and the steps is provided with rounded front-edges 143.
[0073] In short, the invention relates to a cardboard formwork 100 for concreting a stair as shown in Figure 1, wherein concrete is being poured into the cardboard formwork during concreting. The cardboard formwork is constructed by folding and/or assembling one or more cardboard elements 110, and the one or more cardboard elements are cut with predetermined cuts 120 and/or cutouts 130. The assembled cardboard element(s) facing the concrete constitute a substantial part of the formwork, the formwork being capable of supporting the prefabricated stair during the process of concreting said stair.
[0074] The invention lowers production time, improves the working environment due to lower weight and is more environmentally friendly because cardboard can normally be recycled more easily than wood, or metal.
[0075] The invention can be implemented by means of hardware, software, firmware or any combination of these. The invention or some of the features thereof can also be implemented as software running on one or more data processors and/or digital signal processors.
[0076] The individual elements of an embodiment of the invention may be physically, functionally and logically implemented in any suitable way such as in a single unit, in a plurality of units or as part of separate functional units. The invention may be implemented in a single unit, or be both physically and functionally distributed between different units and processors.
[0077] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.
1. A cardboard formwork (100) for concreting a prefabricated stair (140), wherein concrete
is being poured into the cardboard formwork during concreting, and wherein:
- the cardboard formwork is constructed by folding and/or assembling one or more cardboard elements (110), and
- the one or more cardboard elements are cut with predetermined cuts (120) and/or cutouts (130), and
wherein the assembled cardboard element(s) facing the concrete constitute a substantial part of the formwork, the formwork being capable of supporting the prefabricated stair during the process of concreting said stair.2. The cardboard formwork (100) according to any of the preceding claims, wherein the
assembling of the cut cardboard elements (110) is made as a puzzle-assembly (150),
wherein a cut (120) and/or cutout (130) of a first cardboard element are fitting a
cut and/or cutout of a second corresponding cardboard element.
3. The cardboard formwork (100) according to any of the preceding claims, wherein the
assembling of the cardboard elements (110) is made by fixing a cardboard element between
at least two other cardboard elements via tension.
4. The cardboard formwork (100) according to any of the preceding claims, wherein the
cardboard formwork comprises:
- at least one step-piece (160) for forming the steps (141) of the stair being concreted, the step-piece comprising at least one cut cardboard element (110),
- at least one fixing-piece (170), preferably two, for fixing the at least one step-piece into a desired step-form, the fixing-piece comprising at least one cut cardboard element (110), the at least one fixing-piece is being assembled with the at least one step-piece (160), and
- at least one side-piece (180) for forming the sides (142) of the stair being concreted, the side-piece comprising at least one cut cardboard element (110).
5. The cardboard formwork (110) according to any of the preceding claims, wherein the
formwork comprises a baseplate (190), and wherein the formwork is assembled by inserting
one or more cardboard pieces of the formwork into the baseplate for stabilizing and
supporting the cardboard formwork, the baseplate preferably being positioned at the
bottom of the cardboard formwork.
6. The cardboard formwork (100) according to any of the preceding claims, wherein the
formwork during concreting is constructed with reinforcement plates (200) on one or
more of the sides of the formwork, the plates possibly being made of other materials
than cardboard, and wherein the reinforcement plates are interconnected via at least
one through-going threaded rod (210).
7. The cardboard formwork (100) according to any of the preceding claims, wherein the
cardboard formwork is providing a prefabricated concrete stair (140) having one or
more rounded front edges (143), the rounded front edges being constructed by folding
cardboard elements (110) with custom made cuts (120), so that the cardboard element
can form a curvature (230) for forming the one or more rounded front edges.
8. The cardboard formwork (100) according to claim 7, wherein the curvature (230) of
the one or more rounded front edges (143) are made with a predetermined radius, the
radius being determined by at least:
- the number of cuts (120),
- the angle of the cuts, and
- the placement of the cuts on the cardboard element (110) forming the rounded front edges.
9. The cardboard formwork (100) according to any of the preceding claims, wherein the
cardboard formwork is providing a stair (140) having one or more string coves (144).
10. The cardboard formwork (100) according to claim 9, wherein the one or more string
coves (144) are constructed by introducing at least one string-cove-piece (240) into
the cardboard formwork, the string-cove-piece being an elongated cut cardboard element
(110) positioned between a side-piece (180) cardboard element and a step-piece (160)
cardboard element of the cardboard formwork.
11. The cardboard formwork according to claim 9 and 10, wherein the at least one string-cove-piece
(240) is inserted into an adapted cutout (181) of the side-piece (180) element and
being adjacent to the step-piece element (160).
12. A method for manufacturing a cardboard formwork (100) for concreting a prefabricated
stair (140), preferably concreting the stair in one piece, the method comprising:
- providing (S1) one or more cardboard elements (110),
- performing (S2) a cutting with a cutting apparatus of one or more cuts (120) and/or cutouts (130) in the one or more cardboard elements,
- forming (S3) a formwork by
- folding the one or more cut cardboard elements at the one or more cut and/or cutouts, and/or
- assembling the cut cardboard elements, which are being cut to fit each other, and
wherein the assembled cardboard element(s) facing the concrete constitute a substantial part of the formwork, the formwork being capable of supporting the prefabricated stair during the process of concreting said stair.13. A method for manufacturing the cardboard formwork (100) according to claim 12, wherein
the cardboard formwork is assembled as a puzzle (150), where cuts (120) and/or cutouts
(130) of first cardboard element (110) is fitting a cut and/or cutout of a second
corresponding cardboard element (110), and wherein the first cardboard elements can
be cut to be assembled with a corresponding second cardboard element.
14. A method for manufacturing the cardboard formwork (100) according to claim 12, wherein
the cardboard formwork is assembled by fixing a cardboard element between at least
two other cardboard elements via tension.
15. A computer program being adapted to enable a computer system comprising at least one
computer having data storage means in connection therewith to control a cutting apparatus
for cutting cardboard formwork (100) according to any of claims 1-11.