The present invention concerns a formwork for pouring a concrete beam, for example a lintel or another horizontal supporting element made of concrete, which formwork comprises at least a base element with at least two standing side walls extending in the longitudinal direction thereof.

Such a formwork is known from Belgian patent No. 1,013, 347.

This patent describes among others accessories such as coupling pieces or end parts which can be provided on the side walls of the formwork such that they can be adjusted by means of suitable locking means.

Such locking means mainly consist of at least one spring tongue, which is provided on the end element, and recesses which are provided on the side walls of the base element.

The spring tongue is hereby moved as a pawl over the recesses while the end part is being applied, and it prevents the end part from sliding back.

A disadvantage of this embodiment is that every side wall of the base element must be provided with recesses, which implies that the base element as such cannot be made by means of extrusion. However, this extrusion technique can possibly be applied as a first step for realising the side

walls, after which the recesses can be applied, but such finishing is time-consuming and requires the necessary precaution and accuracy in order to prevent the formation of cracks and burrs.

The above-mentioned recesses can possibly be provided before the extruded side walls have hardened by impressing the wall parts. However, the risk hereby is that this treatment may result in the side wall being deformed or in internal stress being created in the side walls.

The present invention aims, a formwork for pouring a concrete beam which remedies these disadvantages.

The main subject of the invention is a formwork onto which can be applied an accessory, such as. a coupling piece or an end part, without the above-mentioned recesses having to be provided in the side walls, so that these side walls can be realised in a very simple manner by means of extrusion, without any finishing being required.

According to the invention, cavities are provided in the crosscut ends of the side walls with which coupling parts, such as protrusions or projections, co-operate, which are provided on the crosscut ends of an accessory which can be applied on the side walls. In particular, the longitudinal axis of the cavities runs parallel to the longitudinal direction of the base element, and these cavities are provided over the entire length of the side walls.

According to a first preferred embodiment, the above- mentioned cavities are formed of protrusions or edges situated on the outside of the side walls.

This embodiment is particularly advantageous when use can be made of protrusions or edges which are already provided on the outside of the side walls for other requirements.

According to the most preferred embodiment, the side walls are made double-walled, whereby such a double-walled side wall consists of an inner wall, an outer wall and ribs situated between the inner wall and the outer wall, and whose section, perpendicular to the longitudinal direction of the base element, represents an identical pattern of cavities everywhere.

What precedes offers the advantage that the base element can be shortened to any length whatsoever.

It is clear that the positions of the coupling parts, such as protrusions or projections, on the crosscut end of an accessory, will correspond to the positions of the cavities in the side walls.

Moreover, it is clear that the outside dimensions of the coupling parts, such as protrusions of projections, should be such that they fit in the cavities in a clamping manner at the height of the crosscut ends in the side walls of the base element.

To this aim, the formwork according to the invention consists of at least a base element, formed of at least two side walls extending in the longitudinal direction of the formwork, as well as at least one accessory which can work in conjunction with the base element, in particular a coupling piece or an end part, whereby the above-mentioned side walls of the base element are provided with cavities extending in the longitudinal direction on the one hand, and whereby the accessory is provided with coupling parts which can co-operate directly or indirectly with the crosscut ends of the side walls on the other hand.

In order to better explain the characteristics of the invention, the following preferred embodiment is described as an example only without being limitative in any way, with reference to the accompanying drawings, in which: figure 1 represents a formwork according to the invention in perspective ; figure 2 is an exploded view of the formwork according to figure 1; figure 3 represents an end part in perspective and to a larger scale; figure 4 represents a section according to line IV-IV. in figure 1 to a larger scale ; figure 5 represents a variant of the part indicated by F5 in figure 3.

The formwork according to the invention mainly consists of a U-shaped base element 1 and at least one accessory 2, in this case an end part.

The base element 1 consists of a bottom 3 and two standing side walls 4 and 5 which are connected to the bottom 3 in a detachable manner in this embodiment.

Each side wall 4 and 5 consists of a wall 6, which is made mainly flat on the inside, and which has protrusions 7,8 and 9 on the outside extending over the entire length of the side wall 4 and 5.

The protrusions 7 and 8 are mainly L-shaped, whereby the flanges 10 and 11 of these protrusions 7-8 are directed towards each other and whereby cavities 12 and 13 are formed in this manner.

The lower protrusion 9 forms a widening at the lower edge of the side walls 4 and 5, which gradually narrows towards the width of the wall 6 via a transition part 14.

The width of the protrusions 7-8 and 9 is measured as of their outer edge to the inner wall of the side walls 4-5 and for the three of them simultaneously.

On the inside of each side wall 4 and 5, at the above- mentioned transition part 14, is provided an inner groove 15 which extends over the entire length of the side wall concerned.

The bottom 3 consists of a loose plate which fits with its edges in the grooves 15 of the walls 4 and 5.

In this embodiment are further provided U-shaped connecting means in the shape of brackets 16 which can connect the upper edges and the lower edges of the side walls 4-5.

These brackets have hook-shaped bent far ends 19 and 20 on the free ends of the flanges 17 and 18 which can work in conjunction with the protrusions 7 on the upper edges of the side walls 4 and 5, with the protrusions 9 on the lower edges of these side walls 4 and 5 respectively.

The widths of the side walls 4 and 5, at the protrusions 7 and 9, are equal, whereas the heights of the protrusions 7 and 9 are also equal, such that one and the same bracket 16 can be used at the top as well as at the bottom of the base element 1.

As represented in figure 1, and into greater detail in figure 4, the side walls 4 and 5 are made double-walled, whereby the inner wall 21 and the outer wall 22 are connected by means of ribs 23 which run over the entire length of the side walls 4 and 5. Between the inner wall 21, the outer wall 22 and the ribs 23 are thus formed cavities 24, which also extend over the entire length of the side walls 4 and 5.

In a similar manner, the protrusions 7,8 and 9 are multi- walled, in particular double-walled, as a result of which cavities 24 are formed as well.

Instead of flat, horizontal ribs 23, also connecting parts can be present between the inner wall 21 and the outer wall 22 extending in another direction or having another shape.

By applying ribs at an angle, it is thus possible to obtain cavities, for example, with a triangular section.

The accessory 2, in this case an end part, is mainly U- shaped with a body 25 with two flanges 26 and 27.

At the free ends of the flanges 26 and 27 is provided an outward directed edge 28 forming a widening or shoulder.

On the end part 2, in this case on the edge 28, are provided coupling parts or projections 29 whose longitudinal axis is situated mainly in the prolongation of the flanges 26 and 27.

The projections 29 are situated at a mutual distance A, which corresponds to the mutual distance B of the cavities 24 of the side walls 4 and 5. Moreover, the projections 29 have dimensions which allow them to work in conjunction with the cavities 24 and/or possibly 12-13. In particular, the coupling parts or projections 29 are made such that they fit in the cavities 24 and/or 12-13, preferably in a clamping manner.

The projections 29 are preferably conical, with the narrowing directed away from the edge 28.

At the bottom of the flanges 26 and 27 is provided a protruding part 30,31 with an outer. wall 32-33 whereby, in the given embodiment, the distance between these outer walls 32 and 33 is equal to the distance between the side walls 4 and 5 at the protrusions 7 and 9. Moreover, the height of the outer walls 32-33 is in this case equal to

the height of the protrusions 7 and 9 of the walls 4 and 5, such that one and the same bracket 16 can work in conjunction with the protruding parts 30 and 31.

The use of the above-described formwork according to the invention for pouring a concrete beam is very simple and as follows.

In order to pour for example a concrete beam which, as represented in figure 1, rests on a wall 34 on one side and on a diagonally directed wall 35 on the other side, one proceeds as follows.

First, the distance between the walls 34 and 35 is measured. This measurement determines the length of the base element 1, in particular of the side walls 4 and 5 and of the bottom 3, and of the number of brackets 16 to be applied. The side walls 4 and 5 are hereby normally selected somewhat longer than said distance, whereas the bottom 3 is selected equal to this distance or somewhat smaller than this distance, as a function of the positioning of the above-mentioned end part 2.

The width of the wall 34 determines the width of the bottom 3 and the width of the end part 2, as well as of the brackets 16.

According to a first possibility, the length of the accessory or end part 2 can be selected as a function of the size of a supporting surface upon which this accessory

2 must rest, i. e. in the example represented in figure 1, as a function of the thickness of the wall 35.

According to a second possibility, it is possible to work with an end part 2 having a standard length which corresponds to the thickness of the usual largest wall thickness available. If the diagonally directed wall 35 is narrower than the length of the flanges 26, 27 of the accessory 2 then, a bracket 16 can be provided over the protruding parts 30-31, in order to cover the distance which is then formed between the bottom 3 and the wall 35, at least when this bottom 3 extends as far as the side walls 4 and 5, so that no concrete can run off while the concrete beam is being poured.

To this end, the width of a bracket 16 can correspond exactly to the difference between two usual wall thicknesses, whereby the length of the flanges 26-27 in this case corresponds to the larger wall thickness.

Preferably, brackets 16 of different standard dimensions will be produced, such that it is possible to work with a single end part 2 for different wall thicknesses.

According to a variant which is not represented, also other brackets than those used to keep the side walls together can be used to bridge an opening in the bottom, whereby they can be either or not fixed to the end part 2 in the above-mentioned manner.

When no bracket 16 is used under the end part 2, the length of the bottom 3 will be adjusted such that it fits exactly between the walls 34 and 35.

The bottom 3 is pushed in the grooves 15 of the side walls 4 and 5, and brackets 16 are provided over the protrusions 9 on the bottom side.

The accessory 2 is provided on one far end of the base element 1 by clamping the coupling parts or projections 29 of the accessory 2 in the cavities 24 of the side walls 4 and 5.

Subsequently, the thus formed formwork is possibly provided with a reinforcement 36, which may be positioned in the formwork for example by means of spacer sleeves. The body 25 of the accessory 2 can be provided with openings through which the bars of this reinforcement 36 may protrude, in order to pour concrete right after the concrete beam has been formed.

The reinforcement 36 is preferably prefabricated, and if necessary sawn to the required length.

Next, the brackets 16 are provided over the protrusions 7 on the top side of the side walls 4 and 5.

At the free end of the. formwork, where the side walls 4 and.

5 extend past the bottom 3, at the height of the above- mentioned transition part 14, is made a hole 37 in both side walls 4 and 5, through which can be provided a pen 38.

When the formwork is being provided, one has to make sure that the accessory 2 rests on the top course of bricks of the diagonally directed wall 35, with the body 25 of the accessory 2 in line with the back side of the wall 35. The bottom 3 thereby connects to the front side of the wall 35, and on the other far end to the crosscut side of the wall 34, where the formwork, through the doing of the pen 38, rests on the course of bricks 39 of the wall 34, whereby the formed space for the concrete beam to be poured is sealed by a course of bricks 40 situated on top of it.

On this far end, the side walls 4 and 5 are situated against the wall 34 on either side, over a distance which depends on the length of the selected base element 1.

Next, the, concrete is poured between the side walls 4-5.

After the concrete has hardened, the brackets 16 are removed, as well as the accessory 2, after which also the side walls 4 and 5 and the bottom 3 can be recovered.

The manufacturing of a formwork according to the invention is very simple on the one hand, while the assembly and disassembly of the formwork is very simple as well on the other hand, and also the cleaning can be done very quickly, since the concrete only makes contact with the flat inner side of the side walls 4 and 5, the flat bottom 3 and the flat inner side of the accessory 2.

Since the protrusions 7,8 and 9 on the outside of the side walls 4 and 5 and the ribs 23 in the double-walled side

walls 4 and 5 extend over the entire length of the side walls 4 and 5 of the base element 1, all parts of the base element 1 can be made by means of extrusion.

Although it is not represented in the figures, the side walls 4 and 5 and the bottom 3 of the base element 1 can also be connected in an inseparable manner. The bottom 3 and the side walls 4 and 5 are then made as a whole.

Such an embodiment offers the advantage that the assembly no longer has to take place on the building site.

It is clear that an accessory 2 can be provided with coupling parts or projections 29 which can work in conjunction with the cavities 12 and 13 of the side walls 4-5. The position, mutual distance and the outside dimensions are in this'case adjusted to the corresponding dimensions of the cavities 12 and 13 on the crosscut ends of the side walls 4 and 5.

It is also clear that the coupling parts or projections 29 and the cavities 12,13 or 24 may assume various shapes, such that the mutual position and design of the coupling parts or projections 29 on the one hand, and the cavities 12-13 or 24 on the other hand allow for the co-operation.

The base element 1 as well as the accessory 2 are preferably made of synthetic material, but they can also be made of another suitable material.

It is clear that the invention also concerns other accessories than end parts, such as for example bends, T- pieces, connecting pieces or the like, whereby also connections with similar coupling parts will be applied then.

Between the base element 1 and. an accessory 2 can be provided mechanical locking means which prevent them from shifting away from each other. A number of examples thereof are schematically represented in figure 5. A first possibility consists in that an extended part 41 is provided on the flanges 26-27 in which is formed an opening 42 through which can be inserted a pen 43 which is pushed into the side wall 4-5 concerned. A second possibility consists in that in the extended part 41 is formed a recess 44 which can form a seating for a locking element which meshes analogously to the pen 43 in the side wall 4,5 respectively. According to a third possibility, an opening 45 is made in one or several of the projections 29, such that a pen 46 can be provided through the side wall 4-5 concerned until it meshes in this opening 45. Naturally, other sorts of locking means are not excluded either.

It should be noted that, as indicated with reference 47 in figure 3, the parts 30-31 can also be made longer, in order to make it possible for brackets 16 of different widths to be efficiently fixed to the end part 2.

It is clear that it is also possible to work with other sorts of filling pieces, combined with an end part of a certain standard dimension.

Instead of working with brackets 16 to span an opening in the bottom, one could also work with extension pieces for the flanges 26-27 which are pushed on the end part 2, when an end part 2 which corresponds to the thinnest available walls is taken as a basis.

The invention is by no means limited to the above-described embodiments given as an example and represented in the accompanying drawings; on the contrary, such a formwork can be made in different shapes and dimensions while still remaining within the scope of the invention.