TITLE

REUSABLE MODULAR FORMWORK FOR PRODUCING STRAIGHT AND/OR ANGULAR FORMWORK ASSEMBLIES

DESCRIPTION The present patent relates to equipment for producing building constructions and in particular concerns a new formwork or system of reusable modular formworks for the production of straight and/or angular formwork assemblies or formworks.

Reusable formworks are known, consisting of prefabricated elements that can be removed after setting of the concrete.

In particular formworks for the production of vertical walls are known, consisting of substantially straight panels, made of sheet metal or wood.

Said panels are extremely heavy and cumbersome and require external reinforcement and supporting structures. Reusable modular formworks are also known consisting of elements made of thermoformed plastic.

Said plastic modular formworks have the advantage of being lighter and more compact than the known formworks made of sheet metal or wood, hence they can be handled more easily by the operators. Said modular formworks for the production of vertical walls are provided with a smooth flat wall, or formwork back, to prevent adhesion of the concrete mix, and with a series of stiffening ribs, protruding perpendicular from the side opposite said smooth surface.

The panel comprises, in particular, both perimeter ribbing, along the perimeter of the panel, and a number of ribs distributed over the surface of

the panel.

Said perimeter ribbing also constitutes the lateral surface for coupling with the adjacent formworks, which are aligned with one another against said lateral surfaces.

For fixing said panels to one another, said perimeter ribbing is provided with through holes for the insertion of keys or closing and fastening elements.

For the production of angular formworks, it is necessary to provide an inner formwork assembly or formwork (CI) consisting of panels arranged so as to form an angle of 270°, and an outer formwork assembly or formwork (CE), where the panels are arranged so as to form an angle of 90°, as shown schematically in figure 1.

Said angular formworks are produced by using straight panels, which are arranged according to the required angle to delimit the inner angular surface and the outer angular surface between which the concrete is cast.

The use of said straight panels, however, involves serious problems of alignment, perpendicularity and stability.

The subject of the present patent is a new type of reusable modular formwork for the production of straight and/or angular formwork assemblies or formworks, with closing key for alignment and fastening of adjacent formworks.

The main purpose of the present invention is to produce straight and/or angular formworks, i.e., in particular, to delimit both the inner and outer straight and angular surfaces of the formworks between which the

construction is cast.

A further object of the present invention is to facilitate and accelerate the production of formwork assemblies or formworks that do not involve problems of alignment, perpendicularity and stability.

An advantage of the present invention is that it is lightweight and stable, without requiring particular use of external reinforcement and supporting structures.

A further object of the present invention is to produce angular walls of any thickness using the same elements.

These and further objects, direct and complementary, are achieved by the new formwork or system of reusable modular formworks for straight and/or angular formwork assemblies and formworks with closing keys for alignment and fastening. The present invention provides for the use of complementary modular elements for the production of straight and/or angular formworks, i.e. one or more elements which, shaped and arranged as described below, constitute the straight, inner angular and outer angular formwork back surfaces for the concrete casting. Said elements, hereinafter called straight elements, inner angular elements and outer angular elements, are substantially straight with linear development, of a generically parallelepiped shape and made of thermoformed plastic. Said elements each have at least one main smooth formwork back surface, while, on the opposite side, they are provided with stiffening ribs.

The inner angular element, i.e. the element to be used preferably for production of the inner angle of the formwork (270°), comprises two smooth formwork back surfaces square to each other and with edge in common, hereinafter called main smooth surface and lateral smooth surface respectively.

Said smooth surfaces delimit the inner angular surface of the building construction to be produced.

The straight element and the outer angular element, i.e. the element to be used preferably for production of the outer angle of the formwork (90°), have one single main smooth formwork back surface, substantially straight.

The surface opposite said main smooth surface is provided with both perimeter and intermediate stiffening ribs, preferably positioned perpendicular to the surface itself. The outer surface of said perimeter ribbing constitutes the surface for coupling with the adjacent formwork elements.

Each of said perimeter ribbings consists of at least two slightly spaced parallel walls, with relative transverse stiffening partitions which provide greater rigidity and resistance to deformation and breaking. Said perimeter ribbing is provided with through holes, i.e. positioned so as to be aligned with the corresponding holes provided on the perimeter ribbing of the other adjacent modular formwork elements. Said holes are used for alignment and fastening of adjacent elements, by means of closing key, described below, or other similar devices. To permit connection between adjacent elements, said holes are arranged square to the adjacent element coupling surfaces.

Therefore, the axis of each of said holes is positioned parallel to the main smooth form work back surfaces.

In particular, the axes of the holes provided on the straight elements, used for the production of straight formworks, are square to the coupling surfaces, i.e. square to the perimeter ribbing and parallel to the main smooth surface.

The inner and outer angular elements of the formwork also comprise, in addition to said holes obtained parallel to the main smooth formwork back surface, further holes with axis positioned square to said main smooth surface.

Said holes with axis square to the main smooth surface allow for positioning and fastening of said angular elements square to the adjacent elements, to produce an angular formwork, for both the outer angle and the inner angle. In particular, said holes are delimited by a lateral cylindrical surface having one or more linear grooves positioned longitudinally to the cylindrical surface itself, suitable for insertion of the closing key as described below. Said closing key comprises a substantially cylindrical body with grip preferably perpendicular to the cylindrical body. Said cylindrical body has a section corresponding to the dimensions of said holes and one or more protrusions at the head, i.e. at one end, having a form corresponding to said grooves obtained on the cylindrical surface of said holes. To connect the adjacent formwork elements, said cylindrical body of the closing key is inserted in a hole so as to cross the perimeter ribbings of both

the elements positioned against each other.

When the head of the cylindrical body protrudes from said holes, the closing key can be rotated so that said protrusions of the cylindrical body rotate from the position corresponding to said grooves to the semicircular edge of the hole, thus preventing the closing key from coming out and connecting the two modular elements to each other.

The inner edges of said protrusions at the head of the cylindrical body of said closing key are slightly slanting to aid tightening and adhesion of the elements. Therefore, to permit rotation of the closing key, said cylindrical body of the closing key must be slightly longer than the sum of the thickness of two perimeter ribbings.

To produce the angular form work, inner or outer, two adjacent elements must be connected in a square position, aligning the holes with axis parallel to the smooth surface of a straight formwork element with the holes with axis square to the main smooth surface of one or more inner or outer angular elements.

Said closing key must therefore be inserted into said holes and rotated, as previously described, to fix the two adjacent elements. To permit the rotation of said closing key, said inner and outer angular elements are shaped and produced as described below.

According to the preferred solution, to prevent the head of the closing key projecting beyond said main smooth surface, the inner angular element has a thicker section at the level of the edge between said main smooth surface and said lateral smooth surface and it therefore follows that the holes with

axis square to the main smooth surface are deeper than the holes with axis parallel to said main smooth surface.

Therefore, for said closing key to permit connection between the two adjacent modular elements, the cylindrical lateral wall that delimits the holes of the inner angular element, square to the main smooth surface, has one or more seats or diameter variations obtained in an intermediate position, which house the protrusions of the cylindrical body of said closing key.

This permits the rotation of said closing key inside the hole and insertion of the protrusions in the related seat, thus connecting the two adjacent elements provided with stiffened lateral edges.

Therefore by using said inner angular element positioned alongside straight formwork elements, an angular surface is obtained which forms the inner smooth angular surface of the construction to be produced. For production of the outer formwork, i.e. to delimit the outer angular surface of the construction, said outer angular element is preferably used, produced as described below.

Said outer angular element also comprises, in addition to said holes with axis parallel to the main smooth surface, further holes square to said smooth formwork back surface, aligned near one side of the element, where the section of said element is less thick in order to permit insertion and rotation of the closing key inside said holes.

To delimit the outer angular surface of the construction, said outer angular element must be positioned adjacent to a straight formwork element, where said straight element must be positioned perpendicular to the smooth wall of

the outer angular module, aligning the holes square to the straight surface of the outer angular element with the holes parallel to the main smooth surface of the straight element.

Said straight element must also be positioned so that the smooth surface is facing the same way as the smooth surface of the outer angular element, thus forming, overall, a smooth surface with an angle of 90°. In an alternative solution for the production of said angular formworks, both inner and outer, said inner and outer angular elements do not feature widening or narrowing of section; they comprise one main smooth surface and at least one lateral smooth surface, square to each other and with edge in common.

Said formwork elements therefore have constant thickness equal to the length of said lateral smooth surface. Each element comprises, at least one end, holes with axis square to said lateral smooth surface and to the perimeter ribbing, and holes with axis square to said main smooth surface, i.e. parallel to said lateral smooth surface, and where all said holes have the same depth. Therefore, to connect two adjacent elements, the elements are simply placed side by side in the required position, aligning the holes of the respective elements and inserting closing keys of different lengths.

To prevent the head of the key protruding from the main smooth formwork back surface, said holes with axis square to said main smooth surface can also have a variable section, as previously described, consequently using shorter keys which can be rotated inside the thickness of the angular element.

The present invention also provides for the use of plugs for closing the holes obtained on said main smooth formwork back surface, positioned flush with or protruding from said smooth surface.

The characteristics of the present invention will be better clarified by the following description with reference to the drawings, attached by way of non-limiting example.

Figure 1 shows schematically the arrangement of the formworks for producing an angular wall, indicating the outer formworks (CE) and inner formworks (CI) and the panels forming the formworks. Figure 2 shows a perspective view of the inner angular element, while figure

3 shows a perspective view of the outer angular element. Figures 4a, 4b and 4c show in detail, in a perspective view, front and rear, the hole obtained on said inner angular element for insertion of the closing key. Figure 5 shows the section of the hole for insertion of the closing key, according to section b-b indicated in figure 4c.

Figure 6 schematises a possible arrangement of the inner and outer angular elements and of the straight elements for the formwork of an angular wall. Figure 7 shows a formwork complete with the various elements. The inner (I) and outer (E) complementary angular elements have a generically parallelepiped shape and are made of thermoformed plastic. Both said angular elements (I) and (E) have at least one smooth formwork back surface (SiI) and (SE), while, on the opposite side, they are provided with perimeter (NP) and intermediate (NM) stiffening ribs. Said inner angular element (I) comprises, in particular, one main smooth

surface (SiI) and one lateral smooth surface (Si2) of the form work back square to each other, i.e. forming an angle of 270°, and having a common edge.

On the side opposite said main smooth surface (SiI), said inner angular element (I) is provided with both perimeter (NP) and intermediate (NM) stiffening ribs, arranged preferably in a position perpendicular to the surface of the element.

Said perimeter ribs (NP) consist of two parallel adjacent walls (NPi) and

(NPe), with transverse stiffening partitions (T), and are provided with through holes (F) square to them, positioned so as to be aligned with the corresponding holes (F) provided on the perimeter ribs (NP) of the adjacent form work elements (P).

The outer surfaces of said perimeter ribs (NP) constitute the surfaces (X) for coupling with the adjacent straight elements (P). Said straight elements (P) comprise one single smooth form work back surface (S) and are provided, on the side opposite said smooth surface (S), with perimeter (NP) and intermediate stiffening ribs.

Said holes (F), square to said perimeter ribs (NP), are used for aligning and fastening adjacent elements, by means of closing key (C) or other connection devices.

In particular, said holes (F) are delimited by a cylindrical lateral surface

(Fl), with preferably circular section with one or more longitudinal linear grooves (F2) suitable for insertion of the closing key (C) as described below. Said closing key (C) comprises a substantially cylindrical body (Cl) with

grip (C2) preferably perpendicular to the cylindrical body (Cl). Said cylindrical body (Cl) has a section corresponding to the form of said hole (F) square to the perimeter ribbing (NP) and comprises one or more protrusions (C3) positioned at the head and having a form corresponding to said grooves (F2) obtained on the cylindrical surface (Fl) of said holes (F).

To connect two adjacent elements, (P), said cylindrical body (Cl) of the closing key (C) is inserted in the holes (F) so as to cross the perimeter ribs (NP) and (NP) of both the adjacent elements (P). When the head of the cylindrical body (Cl) protrudes from said holes (F), the closing key (C) can be rotated so that said protrusions (C3) of the cylindrical body (Cl) shift from the position corresponding to said grooves (F2), thus preventing the closing key (C) from coming out. The inner angular element (I) is provided both with holes (F) square to said perimeter ribbing (NP) and further holes (FL) square to said main smooth surface (SiI), where said holes (F) and (FL) have different lengths.

In particular, said holes (FL) have greater longitudinal dimensions than the holes (F) obtained on the perimeter ribbing (NP), i.e. their depth is equal to the entire thickness of the inner angular element (I), that is, equal to the length of the smooth surface (Si2). Each of said holes (FL) is delimited by a substantially cylindrical surface

(Fl) of the type previously described, arranged square to said main smooth surface (SiI) and parallel to said lateral smooth surface (Si2). Aligning the holes (F), with axes parallel to the smooth surface (S) of a straight formwork element (P), with the holes (FL), with axes parallel to the main smooth surface (SiI) of said inner angular element (I), as shown in

figure 5, an overall thickness is obtained greater than the length of the cylindrical body (Cl) of the closing key (C).

Therefore, the cylindrical lateral wall (Fl) which delimits each of said holes (FL) of the inner angular element (I) has one or more seats or diameter variations (F3), obtained in an intermediate position, housing the protrusions

(C3) of the cylindrical body (Cl) of said closing key (C). This permits rotation of said closing key (C) inside the hole (FL) and insertion of the protrusions (C3) in the related seat (F3), thus connecting the two adjacent elements (I) and (P). To prevent the concrete mix penetrating the inlet of said holes (FL), the present invention also comprises, for each hole (FL), a closing plug (K) positioned at the level of said main smooth surface (SiI). By using said inner angular element (I) alongside straight formwork elements (P), two smooth surfaces are obtained square to each other forming the inner angular surface of the formwork for the concrete casting.

For production of the outer formwork, i.e. to delimit the outer angular surface of the construction, said outer angular element (E) is preferably used, as described below. To delimit the outer angular surface of the construction, said outer angular element (E) must be positioned adjacent to a straight formwork element (P), where said straight element (P) must be positioned perpendicular to the smooth surface (SE) of the outer angular element (E), aligning the holes (FF), provided square to the straight surface (SE) of the outer angular element (E), with the holes (F) of the perimeter ribbing (NP) of the straight element (P).

Said straight element (P) must also be positioned so that the smooth surface (S) faces the same way as the smooth surface (SE) of the outer angular element (E) thus forming, overall, a smooth surface with an angle of 90°. Therefore with reference to the preceding description and the accompanying drawings the following claims are made.