Wooden modular element for making walls.

The present patent application for industrial invention relates to a wooden modular element for making walls.

Wooden modular elements for making walls are known on the market, which are composed of a bearing structure made of solid wood and lateral sides made of laminated wood.

Known modular elements are impaired by several drawbacks that are mainly due to the use of solid wood for the bearing structure.

One of the main drawbacks of solid wood consists in wood shrinkage in the panel, due to the intrinsic composition of wood. Shrinkage has three consequences: dimensional changes, deformations and development of internal stress in the material.

Moreover, the severity and negative effect of these consequences on the qualities of the different varieties of wood can be easily augmented by incorrect drying processes.

The values of total volumetric shrinkage of solid wood are comprised between 9% and 23% approximately, with high variability also between samples taken from the same trunk.

Shrinkage has different values in the three fundamental anatomic directions

(axial, radial and tangential) because solid wood is anisotropic. In particular, contraction in axial direction is very small compared to contraction in tangential direction, whereas contraction in radial direction is approximately half of contraction in tangential direction.

Total axial shrinkage can vary from 0.1 % to 0.8% (most frequent values: 0.2%-0.5%); total radial shrinkage from 2% to 12% (most frequent values: 3%-6%) and total tangential shrinkage from 4% to 23% (most frequent values 6%-12%).

Wood anisotropy against shrinkage is the main cause of the following drawbacks (of course, in addition to volume reduction): - distortion of solids: any three-dimensional solid obtained from fresh wood after drying will be impaired, in addition to volume reduction, also by considerable distortion, that is to say the change of ratios between the geometrical dimensions of the piece with respect to initial values (i.e. cross- sections of sawn pieces with ratio between sides not too far from unit tend to assume a rhomboidal shape);

- ovalization of holes: when drilling a hole in axial direction on fresh wood, the cross-section of the hole will initially be perfectly circular; after drying, the hole will tend to deform because the contraction in a direction tangential to the annual growth rings will be higher than contraction in direction to radiuses. Moreover, tangential contraction will tend to increase from the closest points to the furthest points with respect to medulla, thus originating an oval cross- section with "tip" in opposite direction with respect to the medulla; at the end of the drying process the holes drilled in radial direction will have a tendentially elliptical cross-section, arising from the difference between tangential shrinkage and longitudinal shrinkage;

- V-shaped radial slots: in varieties with central medulla, angular shrinkage often induces stress higher than resistance in the material, with consequent opening of wide apart slots;

- warping of tangential boards: it is a type of deformation from shrinkage that occurs in boards that do not contain central medulla, being cut along tangential planes. The side of the board in most tangential position with respect to the opposite side will tend to shrink more than the second one, exerting a tensile force that will bring the sawn piece to curve transversally, always directing the convexity of the curve towards the medulla; warping tends to increase with tangentiality and thickness of the board and it is a defect that considerably reduces processing output. Warping can be reduced, although not eliminated, by forcing the board in flat position during drying; however, this favours the occurrence of internal stress that can cause problems during the next processing operations.

The patent application EP 0 744 507 discloses a modular element for making vertical walls of buildings that comprises intermediate elements disposed between two external parallel panels. Intermediate elements are provided with upper protruding parts and lower recessed parts in such a way to allow for inserting one module on top of the other. However, the lower border of the external panels is situated at the same level as the lower border of the intermediate elements. This configuration prevents from using self-tapping screws to fix two modules.

The purpose of the present invention is to eliminate the drawbacks of the known art, by devising a wooden modular element for making walls characterised by reliability, resistance, homogeneity and stable dimensions.

These purposes are achieved by the present invention, whose features are claimed in the independent claim 1. Advantageous embodiments are disclosed in the dependent claims.

The wooden modular element for making walls of the invention comprises a central bearing structure disposed between two lateral sides. Each lateral side is composed of a panel that acts as formwork. The central bearing structure comprises at least two bodies that act as connection of the two lateral sides. Each body consists of a laminated wood panel.

The laminated wood panel body is provided with a flat protruding part that extends on a vertical plane and protrudes on top with respect to the upper border of the lateral panels.

The lower border of the lateral panels protrudes from the bottom with respect to the lower border of the bodies of the bearing structure, in such a way to generate an air space adapted to receive the flat protruding part of the body of the inferior module.

In this way self-tapping screws can be used to join modular elements placed one on top of the other, in such a way to increase the rigidity of the wall obtained with said modular elements against the horizontal thrusts due to wind and/or seismic phenomena.

The laminated wood used for the bearing structure conjugates the positive properties of solid wood (renewability, lightness, workability, adequate seismic behaviour, etc.) with the characteristics of a more reliable, homogeneous, high-performance material, obtainable in multiple dimensions and shapes with limited energy dispersion and good recyclability properties.

With respect to solid wood, laminated wood has the following advantages: - better resistance and mechanical rigidity properties;

- homogeneity;

- practically negligible bulging and shrinkage of panel;

Laminated wood normally has the best properties in terms of resistance and rigidity (comparable in all directions of the plane); therefore, it is able to originate works with bearing function, not only as intermediate floor or roof elements, but also as punctiform structures with box-shaped section. In the production of laminated wood the crossed arrangement of longitudinal and transversal plates (the plates of each layer are orthogonal to the plates of the adjacent layer) ensures that:

• built material reaches a certain level of homogeneity; • deformation phenomenon of single plates is mutually controlled.

Coming from different parts of the trunk, each board forming the plates is subject to its own particular deformation, thus causing different internal stress levels that are set off mutually. This results in higher reliability of the product, also because the boards are subject to preventive quality control to eliminate any macro defects.

The crossed disposition of the longitudinal and transversal plates of laminated wood allows for reducing bulging and shrinking phenomena to negligible values, while considerably increasing static resistance and dimensional stability.

Therefore laminated wood is a material characterised by predictable and interpretable behaviour.

Additional characteristics of the invention will become evident from the detailed description below, which refers to a merely illustrative, not limiting, embodiment, as shown in the enclosed figures, wherein:

Fig. 1 is an exploded perspective view that shows a wooden modular element according to the invention;

Fig. 1 A is an exploded perspective view of the wooden plates used to make the laminated wood body;

Fig.1 B is an enlarged view of a detail of Fig. 1 that shows the configuration of the laminated wood used for the body of the modular element of the invention;

Fig. 2 is a front view of the modular element of Fig. 1 in assembled condition;

Fig. 3 is a side view of the modular element of Fig. 1 in assembled condition; Fig. 4 is a top view of the modular element of Fig. 1 in assembled condition; Fig. 5 is a perspective view that shows a wall made with the modular elements of Fig. 1 in assembled condition. Fig. 6 is a plan view of the wall of Fig. 5; and Fig. 7 is a front view of the wall of Fig. 1 ;

With the help of the Figures, the modular element according to the invention is disclosed, which is generally indicated with numeral (1 ).

Referring to figs. 1 - 4, the modular element (1 ) comprises a central bearing structure (2) disposed between two lateral sides (3) composed of panels (30) acting as formworks.

The bearing structure (2) comprises at least two bodies (20) consisting in laminated wood panels that act as vertical connection for the two lateral sides (3). The laminated wood panel bodies (20) have a basically square or rectangular section.

The planes of the two bodies (20) are parallel and orthogonal with respect to the planes of the two panels (30) of the lateral sides (3).

Preferably, the thickness of the bodies (20) is higher than the thickness of the panels (30) of the sides. For example, the thickness of each body (20) is comprised in the range from 60 mm to 240 mm.

As shown in Figs. 1 A and 1 B, each laminated wood panel body (20) is obtained by overlapping at least two plates (layers) of wood (26) with grain (fibres) of a plate disposed orthogonally with respect to the grain of the adjacent plate.

Advantageously, an odd number of plates is used, in which the two ending plates have fibres in vertical direction to give higher resistance to peak loads to the body (20).

The body (20) is fixed to the lateral panels (30) on the sides of the thickness of the plates (26) of the body (20) in such a way that the fibres of the ending plates are arranged in vertical direction.

Advantageously, each plate (26) is composed of a plurality of strips (27) with parallelepiped shape, placed one next to the other and glued.

As shown in Figs. 1 A and 1 B, the strips (27) of the ending plates have parallel fibres in vertical direction.

The bodies (20) of the bearing structure have at least one seat or through housing (21 ) for passage of cables or pipes. Two seats (21 ) are preferably provided on the sides of each body (20) in such a way that the body (20) has an overturned-H configuration.

Each body (20) has a basically rectangular configuration with rounded corners (22) that act as invitation for centring when multiple modules (1 ) are stacked.

At least a blind hole (23) is obtained on the upper side of each body (20) to receive a plug (4) used for connection with the body of the superior module. Accordingly, also the lower side of each body is provided with a blind hole (24) (Fig. 2) to receive a plug for connection with the body of the inferior module. Advantageously, the plugs (4) can be made of wood.

The material of the panels (30) of the lateral sides is not important from the static point of view because it is the vertical connection body (20) that acts as bearing element for the entire module (1 ). Therefore, any type of inexpensive material can be chosen for the panels (30) of the sides, because they only act as formwork without any stability function. The lateral sides (3) are preferably made of oriented strand board (OSB) panels (30) with 600x300 mm area and 25 mm thickness.

A longitudinal groove (31 ) is obtained on the lower border of each panel (30) of the sides, whereas a longitudinal rib (32) is obtained on the upper border of each panel (30). This generates a male-female fitting system on the horizontal borders and for the entire length of the lateral sides of the modular element (1 ) in order to fit modular elements (1 ) in overlapped position one on top of the other.

The panels (30) of the sides are fixed to the bodies (20) of the support structure by means of self-tapping screws (5).

Referring to Fig. 2, it must be noted that the lower border of the panels (30) of the sides protrudes in lower position with respect to the lower border of the bodies (20) of the bearing structure, in such a way to generate an air space (6) adapted to receive the upper part of the inferior module. Accordingly, the upper side of the bodies (20) protrudes in upper position with respect to the upper border of the panels (30). Exactly, between the upper border of the lateral panel (30) and the rounded part (22) of the body (20), the body (20) has a flat protruding part (29) that extends on a vertical plane.

In this way, when the two modules are stacked, the flat protruding part (29) of the bodies (20) of a module is housed in the air space (6) of the upper module. Therefore, self-tapping screws can be used to fix two modules.

The self-tapping screw crosses the lateral panel (30) of the upper module and is screwed in the flat protruding area (29) of the body of the inferior module, ensuring perfect fitting between two stacked modules.

The connection of the overlapped modules by means of self-tapping screws also allows for obtaining rigidity of the wall against transmission of horizontal forces due to wind and/or seismic phenomena. Figs. 5 - 7 shows a wall obtained with the modular elements (1 ) of the invention.

Numerous variations and modifications can be made to the present embodiment of the invention by an expert of the field, while still falling within the scope of the invention as claimed in the enclosed claims.