EP3513682B1

EP3513682B1 - Modular support base for supporting an item of furniture and method for the realisation thereof

Info

Publication number: EP3513682B1
Application number: EP18198877.5A
Authority: EP
Inventors: Paolo Scudiero
Original assignee: Scilm SpA
Current assignee: Scilm SpA
Priority date: 2017-10-10
Filing date: 2018-10-05
Publication date: 2024-04-03
Anticipated expiration: 2038-10-05
Also published as: EP3513682A1; IT201700113692A1

Description

TECHNICAL FIELD

The present invention relates to a modular support base for supporting an item of furniture and method for the realisation thereof.
In particular, the invention relates to a modular support base for column structures (in technical jargon also defined as a "column base"), more precisely furniture for the kitchen, e.g. a fridge.

PRIOR ART

Generally, to make home furnishings more aesthetically uniform, such as in the kitchen, it is usual to have household domestic appliances, e.g. the fridge, built into items of furniture made in the same style and material as the rest of the room.
The item of furniture into which the household appliance is built comprises a lower base adapted to support the household appliance and the underlying feet to keep the base raised off the floor. In this way and thanks to other technical/constructive expedients, such as the installation of ventilation grilles or front jigs, the operation of the household appliance is guaranteed without unwanted drawbacks due to the lack of air recirculation and therefore the overheating of the structure because of the heat produced by the motors and/or compressors.
For that purpose it is known to produce so-called column bases, mainly made of plastic material in the form of a quadrilateral with an empty centre or a solid quadrilateral with possible slits. These column bases, are normally made using moulding or extrusion techniques to obtain a single piece, and therefore a solid base, which is resistant and with few critical points for promoting resistance to loads.
However, the prior art presents a series of drawbacks that the present invention wishes to overcome.
A first drawback of such structure produced as a single piece is the difficulty to modulate its dimensions for adapting to individual needs which can change over time, such as the place in which it is to be positioned or in the case of replacing the household appliance that the item of furniture has to contain or for adapting to foreign markets where the dimensions of the items of furniture or fridges or the like are different and particular. In fact, in this case, it is necessary to purchase another mould (often expensive) for creating a base with different dimensions.
Another difficulty is due to the management and transport of the support base as a single piece, i.e. the difficulty encountered in transporting and installing the base at the furniture assembly location.
It is also known a base pad for supporting an appliance during assembly and shipping as described in documents: BE 759 994 , WO99/14131 , DE 87 11 284 , DE 4342362 .

SUMMARY

In this context, the technical task underpinning the present invention is to provide a modular support base of a column structure, prevalently of kitchen furniture such as a fridge, that can obviate the drawback of the prior art mentioned above.
In particular, the object of the present invention is the possibility to obtain a modular product according to different aspects and for each of the components that compose it, so that every user can obtain the most suitable product according to their needs.
Furthermore, another object to be obtained is the supply of a modular support base for supporting items of furniture that can be transported more conveniently so as to be able to assemble it directly in situ.
In general, the present invention is intended for a modular support base for supporting an item of furniture comprising:

a. at least two longitudinal members arranged side by side at a predefined distance depending on a width of the item of furniture or a part of the furniture to be supported, each longitudinal member extending along a longitudinal direction between a front portion and a rear portion;
b. at least one front cross member extending along a transverse direction with respect to said longitudinal direction between two of its own front ends and being interposed between two front portions of two longitudinal members facing each other so that each front end of the front cross member can be connected with a respective front portion of the longitudinal members;
c. at least one rear cross member extending along a transverse direction with respect to said longitudinal direction between two of its own rear ends and being interposed between two rear portions of two longitudinal members facing each other so that each rear end of the rear cross member can be connected with a respective rear portion of the longitudinal members;
d. a junction means for joining said cross members to said longitudinal members, wherein the junction means is interposed between each front end and the respective front portions and between each rear end and the respective rear portions.

The junction means is also configurable between a coupled condition, wherein the ends of the cross members are connected to the longitudinal members forming a modular support base as a single piece, and an uncoupled condition, wherein the cross members are deconstrained from the longitudinal members therefore the modular base is formed by a plurality of mutually deconstrained components.
Therefore, it is substantially possible to assemble the modular support base for supporting an item of furniture as the main components (at least two longitudinal members and at least two cross members) according to this invention are separate but can be connected with the aid of an interposable fixing means.
In other words, the two longitudinal members and the two cross members are realised separately and therefore the base is not realised as a single piece. Advantageously, in this way, once the longitudinal members have been realised according to the depth requirements of the item of furniture, it is possible to cut the cross members to measure according to the width of the item of furniture before joining them to the longitudinal members.
According to one aspect of the invention, each portion of the longitudinal members has at least one lateral projection, in use, facing towards a respective end of a cross member (and towards the other longitudinal member) and each end of the cross members (front and rear) has at least one seat facing the respective portion of the longitudinal member for housing the aforesaid projection. Preferably, each seat is afforded inside the cross member itself according to the extension direction of the cross member. Even more preferably, each seat is defined by the empty space present inside the cross member. It is to be noted that the projection is preferably realised as a single piece with the related longitudinal member. Advantageously, the presence of a projection on a lateral surface of the longitudinal member and a corresponding seat on the respective end of the cross member allows an easy coupling point to be obtained between the components of the modular base in which the junction means can act for completing the connection.
Preferably, the junction means, in the coupled condition, comprises a mechanical locking system of each seat of the cross members on the respective projection of the longitudinal members.
Even more preferably, the mechanical locking system comprises at least one recess (preferably made by punching) at each end of the cross members directed towards the projection for the formation of the mechanical lock. In other words, the recess is afforded on the outer surface of the cross member and defines a narrowing of the internal section of the cross member and therefore of the seat in which the projection is inserted. In this way, the projection remains locked inside the respective seat.
Advantageously, the formation of a mechanical lock confers stability to the structure, not excluding the possibility to change the configuration of the junction means from the coupling condition to the uncoupling condition for the replacement of a component.
As an alternative to punching, the mechanical lock may be performed through other known techniques.
It is to be noted that the modular base has a resting surface of at least one base of the item of furniture and a surface facing the floor opposite the resting surface, wherein each longitudinal member has a plurality of housings at the surface facing the floor, which are preconfigured for the coupling of different types of bases for feet or feet in different positions. It is to be noted that such housings are defined by holes and/or recesses distanced by predefined distances for a plurality of attachments which are different from each other.
For column structures, there is the possibility to install a front plinth for covering the space below the base and the installation of the feet takes place as a function of the width of such plinth, therefore it is advantageous for the surface of the longitudinal member for the coupling of the feet to have useful housings for such positioning and able to be associated with at least part of the bases for feet or the feet available on the market, which differ in shape and size.
According to a further aspect of the invention, the cross members (front and rear) distanced and connected to the longitudinal members form a quadrilateral shaped modular base.
In this way, the central space of the structure which is still free is useful for the recirculation of air in the event that a fridge is positioned, for example.
According to the invention, at least one longitudinal member comprises, along at least one of its lateral surfaces facing outwards and arranged according to a vertical plane, at least one coupling means in the form of pin elements for coupling with at least one appendage of the item of furniture.
The longitudinal members have, according to the invention, on their lateral surface, coupling means, in the form of pin elements, for being able to install protective panels that can also provide aesthetic continuity to the structure of the furniture.
Preferably, furthermore, the front portions of said plurality of longitudinal members have a square shape and a reduced thickness for forming a bas-relief with respect to the resting surface of the item of furniture adapted for the installation of a front jig, e.g. a ventilation grille for improving ventilation below the item of furniture when installed.
According to an aspect of the invention, the plurality of longitudinal members is produced with different materials with respect to the front cross members and the rear cross members. Preferably the former are made of plastic materials, while the cross members are made of metal materials, e.g. aluminium.
The possibility to assemble the various components of the modular base at a later date thanks to the junction means also allows the longitudinal members to be made of a different material from the cross members.
Longitudinal members and cross members perform different functions, therefore if they are made of different materials they can improve their operation and the related characteristics thereof complement each other.
For example, longitudinal members made of plastic can be made easily through a same mould or moulds.
Aluminium cross members, on the other hand, guarantee greater resistance and adaptability (an aluminium cross member can be easily cut if the dimensions of the base need to be reduced, for example).
The method for the realisation of a modular support base for supporting an item of furniture comprises the operating steps of:

a. preparation of a plurality of longitudinal members extending along a longitudinal direction for a determined length depending on the depth of the item of furniture, each longitudinal member having a front portion and a rear portion;
b. preparation of at least one front cross member having a determined length depending on the width of the item of furniture;
c. preparation of at least one rear cross member having a determined length depending on the width of the item of furniture;
d. interposition of at least one front cross member between the front portions of the longitudinal members along a transverse direction with respect to the longitudinal direction and connection of each front portion of the longitudinal members with the respective front ends of at least one front cross member through a junction means;
e. interposition of at least one rear cross member between the rear portions of the longitudinal members along the transverse direction with respect to the longitudinal direction and connection of each rear portion of the longitudinal members with the respective rear ends of at least one rear cross member through a junction means;
f. configuration of the junction means in the coupled condition for the formation of a modular base with a quadrilateral shape;
g. positioning at least one base for a foot or at least one foot for each portion of the plurality of longitudinal members at a specific housing provided at each portion of the plurality of longitudinal members on the surface opposite the resting surface of at least one base of the item of furniture,

It is to be noted that the cross member preparation steps comprise an initial sub-phase in which the cross members are cut to measure according to a pre-chosen width of the base.
According to the invention, the presence on the lateral surface of the longitudinal members of coupling means, in the form of pin elements, makes it possible to install protective panels that can also provide aesthetic continuity to the structure of the furniture.
According to one aspect of the invention, the junction means is configured in a coupling condition through a punching technique.
According to a further aspect of the invention, the step of preparing a plurality of longitudinal members envisages the use of a plastic material and the step of preparing a front cross member and a rear cross member envisages the use of a different material from said plurality of longitudinal members, preferably a metal material.
The possibility to assemble the various components of the modular base at a later date thanks to the junction means also allows the longitudinal members to be made of a different material from the cross members. Longitudinal members and cross members perform different functions, therefore, if they are made of different materials they can improve their operation and related characteristics thereof complement each other, such as lightness, resistance and adaptability (an aluminium cross member can be easily cut if the dimensions of the base need to be reduced, for example).

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, but not exclusive, embodiment of a modular support base for supporting items of furniture, such as built-in kitchen furniture, as illustrated in the accompanying drawings, of which:

▪ Figure 1 illustrates a perspective view of the apparatus in question;
▪ Figure 2a illustrates a view from below of the construction details of the invention;
▪ Figure 2b illustrates the front section of the invention;
▪ Figure 3 illustrates a perspective view of the lower surface of the invention;
▪ Figure 4 illustrates a perspective view of a detail of the longitudinal members;
▪ Figures 5a and 5b illustrate a perspective, exploded view of the modular base, with a view of the upper surface and of the rear surface, respectively.

In the following description, the identical reference characters indicate identical or corresponding parts in the different views.

DETAILED DESCRIPTION

The present invention relates to a modular support base 1 for supporting items of furniture, specifically to a column base for supporting built-in items of furniture.
With reference to the figures cited, a modular support base 1 for supporting items of furniture according to the present invention is indicated in its entirety by reference number 1.
Figure 1 illustrates a possible aspect of the modular support base 1 for supporting an item of furniture, which comprises a plurality of longitudinal members 2, at least one front cross member, at least one rear cross member 4 and a junction means 5.
The use of separate components allows the structure to be modulable according to requirements, while the introduction of a junction means 5 allows the formation of a single structure that can be used.
The longitudinal members 2 are made of plastic material, with moulding or extrusion techniques, for being able to provide for the presence of pin elements for the connection of possible appendages of the item of furniture and for being able to provide for housings 8 of various shapes and sizes for the association of bases for feet or support feet 12 in any position according to the front plinth that is to be installed.
For the support of the lateral flanks of the item of furniture, each longitudinal member 2 may comprise horizontal tabs 13 extending outside the base 1 itself so as to support at least part of the weight of the item of furniture placed above the base 1 (the rest of the weight is however supported by the pin elements). Such horizontal tabs 13 are removable for some applications in which the modular base 1 is used to define an intermediate bottom in a position which is more internal with respect to the item of furniture.
The cross members 3, 4, either front or rear, are a tubular profile with a prevalently square cross section, made of metal material for facilitating the variation of their length according to the variation of the width of the item of furniture to be supported. The cross members 3, 4, interposable and connectable to the two portions 2a, 2b of two different longitudinal members 2 with the function of spacers and supports, are generally made of aluminium as they can be easily shortened in length with cutting techniques free from any corrosion phenomena.
The modular base 1, made of different materials for longitudinal members 2 and cross members 3, 4, combines the characteristics of both materials used: lightness, resistance, ecology, modularity and adaptability to any application situation.
As previously mentioned, the most commonly used materials are aluminium for the cross members 3, 4 and plastic materials for the longitudinal members 2, however the use of other plastic, ferrous (subjected to suitable anti-corrosion treatments) and wood materials is not excluded, materials which are chosen based on the particular properties which the modular base 1 requires.
The longitudinal members 2 extend along a longitudinal direction L for a predetermined length and width between two portions 2a, 2b each, a front portion 2a and a rear portion 2b. The front portions 2a of the longitudinal members 2 have a square shape and a narrowing to form bas-reliefs, on which it is possible to install, for example as shown in Figure 4, a ventilation grille 11 useful for air recirculation for the correct operation of a fridge placed on the modular support base.
The lateral surface of a longitudinal member facing outwards, when the longitudinal member composes the modular base 1 placed in use, and arranged according to a vertical plane, comprises at least one coupling means 9, in the form of pin elements, useful for the installation of covering and protective lateral panels.
Finally, as illustrated in figures 5a and 5b, the lateral surface of the portion of a longitudinal member, front 2a and rear 2b, facing inwards and arranged according to a further vertical plane, has a lateral projection 6a that can be connected with the ends 3a, 4a of the respective cross member 3, 4.
The cross members, front 3 and rear 4, extend between two ends 3a, 4a along a transverse direction T with respect to the longitudinal length L along which the longitudinal members 2 extend and for a length that is a function of the width of the item of furniture or of a portion of the item of furniture that the modular base 1 has to support. The ends 3a, 4a of the cross members 3, 4 have a seat 6b that faces the related portion of the longitudinal member, so that the seat 6b of the end 3a, 4a of the cross member and the lateral projection 6a provided on the longitudinal member are coupled with each other. Usually, two longitudinal members 2 are arranged on the same plane parallel to each other and at a predetermined distance, to form the opposite sides of a quadrilateral, and coinciding with the length of the cross members 3, 4. However, it is possible for the two longitudinal members 2 to be arranged with a mutual angle of inclination comprised between 0° and 90° based on the shape of the item of furniture to be obtained.
To complete the realisation of the modular support base 2 for supporting an item of furniture, a junction means 5 is required, that can be interposed between the ends 3a, 4a of the cross members 3, 4 and the respective portions 2a, 2b of the longitudinal members 2, which can be configured both in an uncoupled condition, in which the modular base 1 is composed of mutually deconstrained components, and a coupled condition, in which the modular base 1 is formed like a single part.
The junction means 5 comprises mechanical locking systems 7 such as a screw/bush or, in the case of using the punching technique, at least one recess for each seat 6b of the end 3a, 4a of the cross members 3, 4 directed towards the lateral projection 6a of the respective portion of the longitudinal member, until at least in contact with the latter for creating a friction point able to lock the mutual movement between the parts.
The components that describe the modular base 1 are positioned along the sides of a quadrilateral, leaving the centre of the structure free, e.g. for having good air recirculation below the item of furniture, in combination with the ventilation grille 11.
The modular support base 1 for supporting an item of furniture described above comprises a resting surface for at least one base of the item of furniture and a surface facing the floor opposite said resting surface, as illustrated in figure 2 and in figure 3. The surface facing the floor, at each portion of each longitudinal member, has a plurality of housings 8 of a circular and substantially square shape. These housings 8 are preconfigured for the coupling of different types of bases for feet or feet 12 in different positions, which are able to keep the modular base 1 raised. The bases for feet or feet 12 must be arranged at a mutual distance as a function of the front plinth that can be installed to cover the bases for feet and the feet 12 themselves and the space subtended by the modular base 1. The bases for feet and the feet 12 currently on the market also have different sizes and shapes that can be installed on the surface facing the floor of the modular base 1 thanks to such housings 8 provided.
A method for the realisation of a modular support base 1 for supporting an item of furniture is also the subject matter of the present patent, comprising the operating steps of:

a) preparation of a plurality of longitudinal members 2 extending along a longitudinal direction L for a determined length depending on the depth of the item of furniture, each longitudinal member 2 of said plurality of longitudinal members 2 having a front portion 2a and a rear portion 2b;
b) preparation of at least one front cross member 3 having a determined length depending on the width of the item of furniture;
c) preparation of at least one rear cross member 4 having a determined length depending on the width of the item of furniture;
d) interposition of said at least one front cross member 3 between said front portions 2a of said longitudinal members 2 along a transverse direction T with respect to said longitudinal direction L and connection of each front portion 2a of said longitudinal members 2 with respective front ends 3a of said at least one front cross member 3 through a junction means 5;
e) interposition of said at least one rear cross member 4 between said rear portions 2b of said longitudinal members 2 along said transverse direction T with respect to said longitudinal direction L and connection of each rear portion 2b of said longitudinal members 2 with respective rear ends 4a of said at least one rear cross member 4 through a junction means 5;
f) configuration of said junction means 5 in the coupled condition for the formation of a modular base 1 with a quadrilateral shape.
g) positioning at least one base for a foot or at least one foot 12 for each portion 2a, 2b of said plurality of longitudinal members 2 at a specific housing 8 provided at each portion 2a, 2b of said plurality of longitudinal members 2 on the surface opposite the resting surface of at least one base of the item of furniture.

For the completion of the item of furniture, thanks to the presence of at least one coupling means 9 in the form of pin elements on the outer side of the longitudinal member, the method described above comprises a further installation sub-step of at least one appendage of the item of furniture, e.g. for covering and protecting the built-in fridge.
The step of configuring said junction means 5 in the coupling condition, according to one aspect of the invention, may take place through the technique of punching the seat 6b of the cross members 3, 4 towards the projections of the longitudinal members 2.
Finally, the step of preparing a plurality of longitudinal members 2 envisages the use of a plastic material and the step of preparing a front cross member 3 and a rear cross member 4 envisages the use of a different material from said plurality of longitudinal members 2, preferably a metal material, for the combination of the different properties of the materials used.

Claims

A modular support base (1) for supporting an item of furniture comprising:
- at least two longitudinal members (2) arranged facing each other at a predefined distance depending on a width of the item of furniture or a part of the furniture to be supported; each longitudinal member of said plurality of longitudinal members extending along a longitudinal direction (L) between a front portion (2a) and a rear portion (2b);

- at least one front cross member (3) extending along a transverse direction (T) with respect to said longitudinal direction (L) between two of its own front ends (3a); said front cross member (3) being interposed between two front portions (2a) of two longitudinal members (2) facing each other so that each front end (3a) of said front cross member (2) can be connected with a respective front portion (2a) of said longitudinal members (2);

- at least one rear cross member (4) extending along a transverse direction (T) with respect to said longitudinal direction (L) between two of its own rear ends (4a); said rear cross member (4) being interposed between two rear portions (2b) of two longitudinal members (2) facing each other so that each rear end (4a) of said rear cross member (4) can be connected with a respective rear portion (2b) of said longitudinal members (2);

- a junction means (5) for joining said cross members (3, 4) to said longitudinal members (2), wherein said junction means (5) is interposed between each front end (3a) of said front cross member (3) and said respective front portions (2a) of the longitudinal members (2); said junction means (5) being interposed between each rear end (4a) of said rear cross member (4) and said respective rear portions (2b) of the longitudinal members (2);

said junction means (5) being configurable between a coupled condition, wherein the ends (3a, 4a) of the cross members (3, 4) are connected to the longitudinal members (2) forming said modular support base (1), and an uncoupled condition, wherein the cross members (3, 4) are deconstrained from the longitudinal members (2) therefore the modular base (1) is formed by a plurality of mutually deconstrained components;

each longitudinal member (2) has a resting surface for supporting at least one base of the item of furniture and a surface facing the floor opposite said resting surface, wherein each longitudinal member (2) has at least one housing (8) at said surface facing the floor preconfigured for the coupling of at least one base for a foot or a foot (12);
characterised in that at least one longitudinal member (2) comprises, along at least one of its lateral surfaces facing outwards and arranged according to a vertical plane, at least one coupling means (9) for coupling with at least one appendage of the item of furniture, wherein said coupling means are pin elements.
The modular support base (1) according to claim 1, wherein
each portion (2a, 2b) of said plurality of longitudinal members (2) has at least one lateral projection (6a), in use, facing towards a respective end (3a, 4a) of a cross member (3, 4);

each front end (3a) of said front cross members (3) and each rear end (4a) of said rear cross members (4) has at least one seat (6b) facing the respective portion (2a, 2b) of the longitudinal member (2) for housing said projection (6a) of said longitudinal member (2).
The modular base (1) according to claim 2, wherein said junction means (5) comprises a mechanical locking system (7) for each seat (6b) of the cross members (3, 4) on the respective projection (6a) of the longitudinal members (2) in the coupled condition.
The modular base (1) according to claim, 3, wherein said mechanical locking system (7) comprises at least one recess at each end (3a, 4a) of the cross members (3, 4) directed towards the projection (6a) for the formation of the mechanical lock.
The modular base (1) according to any one of the preceding claims, characterised in that each longitudinal member (2) has a plurality of housings (8) at said surface facing the floor; said housings (8) being preconfigured for the coupling of different types of bases for feet or feet (12) in different positions.
The modular base (1) according to any one of the preceding claims, wherein said cross members (3, 4) are distanced from each other during the coupled condition for forming said modular base (1) with a quadrilateral shape.
The modular base (1) according to any one of the preceding claims, wherein said front portions (2a) of said plurality of longitudinal members (2) have a bas-relief (10) adapted for the installation of a front jig (11) for improving the ventilation below the item of furniture when installed.
The modular base (1) according to any one of the preceding claims, wherein said plurality of longitudinal members (2) is produced with different materials with respect to said front cross members (3) and said rear cross members (4); said plurality of longitudinal members (2) preferably being made of plastic materials and said front cross members (3) and said rear cross members (4) preferably being made of metal materials.
The modular base (1) according to any one of the preceding claims, characterised in that it comprises at least one foot connected to a respective housing (8) of each longitudinal member (2), wherein said foot extends away from said surface facing the floor for a predefined height so as to distance at least the longitudinal members (2) and the cross members (3, 4) from the floor.
A method for realising a modular support base (1) for supporting an item of furniture, comprising the following operating steps:
a. preparation of a plurality of longitudinal members (2) extending along a longitudinal direction (L) for a determined length depending on the depth of the item of furniture, each longitudinal member (2) of said plurality of longitudinal members having a front portion (2a) and a rear portion (2b);

b. preparation of at least one front cross member (3) having a determined length depending on the width of the item of furniture;

c. preparation of at least one rear cross member (4) having a determined length depending on the width of the item of furniture;

d. interposition of said at least one front cross member (3) between said front portions (2a) of said longitudinal members (2) along a transverse direction (T) with respect to said longitudinal direction (L) and connection of each front portion (2a) of said longitudinal members (2) with respective front ends (3a) of said at least one front cross member (3) through a junction means (5);

e. interposition of said at least one rear cross member (4) between said rear portions (2b) of said longitudinal members (2) along said transverse direction (T) with respect to said longitudinal direction (L) and connection of each rear portion (2b) of said longitudinal members (2) with respective rear ends (4a) of said at least one rear cross member (4) through a junction means (5);

f. configuration of said junction means (5) in the coupled condition for the formation of a modular base (1) with a quadrilateral shape;

g. providing at least one housing (8) for a base for a foot or for at least one foot (12) at said plurality of longitudinal members (2) on a surface which is opposite the resting surface of at least one base of the item of furniture;
characterised in that it comprises a step of realizing at least one coupling means (9) positioned along the lateral surfaces of at least one longitudinal member (2), facing outwards and arranged according to a vertical plane for coupling with at least one appendage of the item of furniture, wherein said coupling means are pin elements.
The method according to claim 10 characterised in that it comprises a step of positioning at least one base for a foot or at least one foot (12) on said plurality of longitudinal members (2) at said predefined housing (8).
The method according to any one of claims 10 to 11, wherein said junction means (5) is configured in a coupled condition through a punching technique performed at a seat (6b) of each cross member (3, 4) with respect to a projection (6a) of each portion (2a, 2b) of each longitudinal member (2) inserted internally into said seat (6b).
The method according to any one of claims 10 to 12, wherein the step of preparing a plurality of longitudinal members (2) envisages the use of a plastic material and the step of preparing a front cross member (3) and a rear cross member (4) envisages the use of a different material from said plurality of longitudinal members (2), preferably a metal material.