AN INSERT FOR A MODULAR CHAIR

This invention relates to an insert for a modular chair of the type specified in the preamble of the first claim.

In particular, this invention relates to an insert for a chair of the modular type. In this text, the term“chair” is, in the broadest sense of the term, any device that enables a user to sit and that may, depending on the configuration, consist of a chair, an armchair, a sofa, or something else for various types of application, including the office, home, garden, luxury, and so on.

As is well known, in the present state of the art, many different types of chairs have been produced, for example with armrests, recliners, slings, or armchairs or sofas and so on, according to the reference market for which the chairs are intended. Historically, chairs are derived from simple benches. The latter are, in fact, equipped with a simple support plane defining the seat structurally connected to at least two support pillars to allow the seat to be raised from the floor.

Currently, chairs are typically designed to allow the support of at least one user, and preferably one, on a plane called a seat. Most chairs also have additional support elements, such as the backrest, and may also comprise armrests and supports for the support of the upper and lower limbs respectively.

Various, widespread types of chairs include: the so-called deck chair, consisting of a folding chaise longue the backrest of which can be reclined at variable angles and on which a sitting or lying position may be assumed, as desired by the user; the curule seat, also developed as the faldstool, with a substantially crossed, or X- shaped, structure, and sometimes folding for the support of the seat; the tripolina that is entirely folding and was used historically in battlefields; the monobloc chair generally made of polymeric material and used for outdoor environments, mainly in the restaurant industry; the rocking chair comprising two curved supports designed to allow the rocking movement typical of the chair in question; and the cantilever chair, very commonly used and comprising only two uprights bent at floor level and at seat level and connected horizontally by a continuous tube.

In addition to the above examples, there are a number of other different types and structures of chair designed to meet aesthetic needs, such as the market demand for a certain shape, or technical needs, resulting for example from the need to optimize the production process while maintaining high quality levels of the chair product.

Examples of this type are described in patent applications US-A-2839126 and US A-5762403 and US-B-6293624 and US2010109414A1 .

The chairs described in the above-mentioned patent applications have such features and configurations as to allow the assembly of the chair starting from elements that can be attached together.

In particular, all the chairs provide the possibility of adapting a finished piece of fabric to a portion of the frame of the chair in such a way as to produce parts of it such as the seat and/or backrest.

In detail, all the solutions mentioned above have a perforated frame inside which a peripheral portion of fabric or strip of fabric can be introduced in such a way as to hook onto it. The attachment mechanism requires, in particular, that a slider trapped in the fabric is inserted into a guide.

The described prior art comprises some significant drawbacks.

In particular, chairs of the type described do not enable the insertion or coupling of additional fabrics or other materials such as padding or the like. In fact, at present, such chairs are designed to only enable the insertion of fabric on the frame or inside the guides of the frame itself taking up most of the space created by the guide.

When you intend to insert more fabrics on the same frame it is necessary, therefore, to modify the frame by obtaining additional guides in order to allow the addition of different materials.

In this situation the technical task underlying this invention is to devise an insert for a modular chair able to substantially overcome at least some of the drawbacks mentioned above.

Within said technical task, it is an important purpose of the invention to obtain an insert for a modular chair that enables the possibilities for composing the chair itself to be widened, by enabling the addition of materials or other elements to the base frame without needing to employ frame processing or replacements and, at the same time, enabling functionalities to be added to the chair itself.

Another important purpose of the invention is to create an insert for a modular chair that is easy and quick to produce, as well as equally easy and quick to install on the modular chair.

The technical task and specified purposes are achieved by an insert for a modular chair as claimed in the appended Claim 1 .

Preferred embodiments are highlighted in the dependent claims.

The characteristics and benefits of the invention will be clarified in the following detailed description of some preferred embodiments of the invention, with reference to the accompanying drawings, wherein:

Fig. 1 shows a front view of a chair according to the invention;

Fig. 2 shows an exploded view of a chair according to the invention; Fig. 3 is the detail of the tensioner and the support portion of a chair according to the invention;

Fig. 4 is a schematic view in perspective of the frame of a chair according to the invention;

Fig. 5a shows the detail of the mechanism made by the hinge of the frame of a chair according to the invention in the rest or pre-assembly configuration;

Fig. 5b shows the detail of the mechanism made by the hinge of the frame of a chair according to the invention in the configuration of use or in the assembled configuration;

Fig. 6 is a cross-section view of the frame of a chair according to the invention with a guide;

Fig. 7 shows the detail of the hinge of a chair according to the invention;

Fig. 8 shows a schematic example of introducing the fabric sliders into the frame guide of a chair according to the invention;

Fig. 9a shows a cross-section view of the frame of a chair according to the invention with two fabrics connected to the frame in a single guide;

Fig. 9b is a cross-section view of the frame of a chair according to the invention with two guides, a fabric and a coupling device in which the fabric and the coupling device are each connected to the frame by means of a special guide;

Fig. 10 is a front view of a chair according to the invention including a fabric covering the bottom of the support portion;

Fig. 11 shows a front view of a chair according to the invention including a coupling device at the bottom of the support portion and a support portion in an embodiment for the office;

Fig. 12 shows a front view of a chair according to the invention including in an alternative embodiment in which the fabric is suspended;

Fig. 13a is a detailed side view of a chair according to the invention in the preferred embodiment shown in Figs. 1 -2;

Fig. 13b is a detailed side view of a chair according to the invention in the alternative embodiment shown in Figs. 9a and 10;

Fig. 13c shows a detailed side view of a chair according to the invention in the alternative embodiment shown in Figs. 9b and 1 1 ;

Fig. 14 shows a perspective view of an insert for the chair according to the invention;

Fig. 15 shows a view from above of an insert for a chair according to the invention;

Fig. 16 represents a side view of an insert for a chair according to the invention wherein the profile of the coupling zone is highlighted;

Fig. 17a shows an example of deformations of an insert for a chair according to the invention for convex structures;

Fig. 17b shows an example of deformations of an insert for a chair according to the invention for concave structures;

Fig. 18 is a perspective view of an insert for a chair according to the invention with a double joining zone, but without external bodies;

Fig. 19 represents a side view of the profile of an insert for a chair according to the invention with a double joining zone;

Fig. 20a shows an example of applying an insert for a chair according to the invention to a modular chair according to the invention; and

Fig. 20b illustrates an example of applying two inserts for a chair according to the invention in a modular chair according to the invention wherein one insert has a double joining zone and one insert has a single joining zone.

In this document, the measures, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words like“almost” or other similar terms such as“approximately” or“substantially”, are to be understood as except for measurement errors or inaccuracies owing to production and/or manufacturing errors and, above all, except for a slight divergence from the value, measure, shape, or geometric reference with which it is associated. For example, if associated with a value, such terms preferably indicate a divergence of no more than 10% from the value itself.

Furthermore, when used, terms, such as“first”,“second”,“higher”,“lower”,“main� ��, and“secondary” do not necessarily identify an order, relationship priority, or relative position, but they can simply be used to distinguish different components more clearly from one another.

Unless otherwise stated, the measurements and data reported in this text shall be considered as performed in International Standard Atmosphere ICAO (ISO 2533: 1975).

With reference to the figures, the reference number 100 globally denotes the insert for a modular chair according to the invention.

The insert 100 is preferably used with a modular chair 1 as described below. Flowever, the insert 100 can be used in any chair that comprises at least one frame and one support structure including, for example, tubular elements. In fact, the insert 100 can be used on any chair in the current state of the art.

The term chair refers preferably to a chair. In any case, the chair could be any device that enables a user to sit and that can, depending on the configuration, also constitute, therefore, devices other than a chair, such as an armchair or a sofa. For example, the chair may also be a seat for a vehicle, such as a car, or other means of transport, such as trains or aircraft.

In addition, the chair is not restricted to a specific use and design, but can be adapted, as convenient, to uses of various kinds such as home use, in the office, or in other environments other than those mentioned: for example, restaurants, hotels, conference rooms, study rooms, or the like.

In particular, the modular chair 1 preferably comprises at least one support portion

2

The support portion 2 is preferably designed to enable a user to rest on it. Therefore, it is basically the part of the chair 1 that can accommodate at least part of the user's body.

The support portion 2 preferably includes, therefore, a frame 20 and a fabric 21. The fabric 21 may be defined by a sheet of fibre only, or it can also comprise padding elements, for example trapped between two strips of fabric.

In any case, the fabric 21 preferably defines a surface 210 and a perimetric area

211

The surface 210 is preferably designed to support the user. Therefore, it preferably defines the support surface for the user and is designed to support the weight force of the user.

The perimetric area 21 1 is, instead, basically defined by the edges of the surface 210. In other words, the perimetric area 21 1 is basically defined by the boundary zone of the surface 210.

The fabric 21 preferably includes composite fibres, i.e. comprising polymeric filaments around which fabric filaments are twisted. This type of fibre enables the fabric to be reinforced or, more generally, the local mechanical properties of the fabric 21 to be modified as desired. The term“local properties” refers to the fact that the surface 210 can be considered as a set of smaller surfaces each defining its own mechanical properties and that can, therefore, vary from surface to surface.

In essence, the conformation of the fabric 21 can be achieved by means of studies and processes such as, for example, finite element theory or other types of methods allowing the surface to be discretized and the local mechanical properties of the discretized elements to be controlled.

The fabric 21 is preferably made by automated knitting machines and, in particular, by machines known as flat bed knitting machines.

With these machines it is possible, as already mentioned, to control the mechanical properties of the discrete elements of the surface 210 in such a way as to enable the fabric 21 to assume the desired characteristics according to the structural elements interacting with it in the chair 1.

The fabric 21 can also be made with conventional weaving machines.

In this case, for example, the fabric 21 may show different mechanical properties within the surface 210, for example, depending on the thread count or texture adopted within the fabric 21.

The fabric 21 may also, whether it is made with computerised technology or with conventional textile technology, include localised support elements. For example, the fabric 21 may include within it metal structures, such as bars or filaments, trapped or woven inside pockets that can be easily made in the fabric 21 , so as to locally increase the stiffness of the surface 210. In this sense, the fabric 21 may appear as a woven surface 210 including ribs or diaphragms, e.g. metallic, designed to reinforce the structure of the fabric 21.

The frame 20 preferably defines, in use or, in other words, when assembled, a closed structure. As a result, the frame 20 extends along a curved trajectory in such a way as to close on itself and create a hole, as is the case with a ring.

The frame 20 does not necessarily have a structure formed of planar portions, but preferably has a complex structure that extends in space in a three-dimensional manner, as shown in particular in Figs. 2, 4, and 8.

A complex structure of this type is, for example, a composite 3D curve, i.e. a curve made along a trajectory that rotates around at least two main axes in three- dimensional space.

The frame 20 preferably defines a condition of use or assembly configuration wherein it creates the closed structure and a rest condition or pre-assembly configuration wherein it assumes a different shape.

In use or in the assembled configuration, the frame 20 is preferably designed to support the fabric 21 under tension at at least part of the perimetric area 21 1 .

The fabric 21 can in fact be fully connected to the frame 20 along its perimetric area 21 1 or can be only partially connected along its perimetric area 21 1 , for example in the case of defining a chair 1 including part of the fabric 21 suspended, as shown in Fig. 12.

This last expedient may also be appropriate if the chair 1 is intended to be produced with different fabrics 21. In fact, the chair 1 could comprise fabrics 21 partly attached to the frame 20 in the perimetric portions and partly attached to other fabrics to make the support portion 2.

In particular, the frame 20 locally tensions the fabric 21 in relation to the shape assumed by the frame 20.

In the rest condition or pre-assembly configuration, instead, the frame 20 can release the fabric 21 . In order to achieve this, the frame 20 preferably, but not necessarily, comprises at least two parts 200.

The parts 200 are portions of frame 20 that may basically coincide with sections of the closed structure defined by the frame 20. They are, preferably, separate from each other and loosely attached to each other at two fixed points. Alternatively, they can be parts of a single piece defining loose points between the parts 200 allowing the individual parts 200 to be identified. In the latter case, the fixed points correspond to the loose points. These fixed points preferably correspond to the endpoints of the parts 200, but other points, e.g. intermediate, may be provided so as to form annular shapes with irregular edges.

The parts 200 are, preferably, loosely attached to each other by means of two hinges

201

The hinges 201 are preferably the means designed to enable the switching of the conditions or configurations of use (assembly) or rest (pre-assembly) of the parts 200 i.e. of the frame 20.

These hinges 201 are preferably mechanical.

In particular, the hinges 201 preferably define the configuration of use, or assembly, wherein the parts 200 actually form the frame 20 and the configuration of rest, or pre-assembly, wherein the parts 200 are folded together in a book fold.

In this way, the overall dimensions of the support plane 2 are reduced when the parts 200, or the frame 20, are in the rest or pre-assembly configuration.

The hinges 201 each preferably define a rotation axis 2a. The rotation axis 2a preferably lies along the sagittal plane, which divides the closed structure into two basically identical portions. In use, the sagittal plane appropriately contains the vertical direction. The rotation axis 2a preferably defines the only degree of freedom granted to the parts 200 of the frame 20. Therefore, the parts 200 are basically designed to rotate, preferably exclusively, around the rotation axis 2a of the hinges 201 .

The rotation axes 2a of the two hinges 201 are conveniently aligned with each other. As a result, the frame 20 can be basically closed or folded, as with a common book, in the rest or pre-assembly configuration, and be reopened by identifying at least one use configuration, or assembled configuration, corresponding to a stable equilibrium configuration wherein the frame 20 tensions the fabric 21 .

In particular, said frame 20 tensions the fabric 21 preferably only when the parts 200 are in use configuration.

In order to implement the use configuration, or assembled or stable equilibrium configuration, the chair 1 according to the invention is preferably configured to allow mutual rotation of the parts 200 in one direction only. In particular, the reciprocal rotation permitted is preferably opposite to the ground, so as to allow the frame 20 to counteract any weight of a body or user placed on the support portion 2.

The term rotation opposite to the ground refers to the fact that, when the 20 frame is opened like a book, it faces the ground in the same way as a book would allow its pages to face the ground, once opened.

In this sense, the chair 1 preferably involves, in a first embodiment, a particular configuration of the hinges 201 .

In detail, and as shown in Figs. 5a, 5b, and 7, each of the hinges 201 includes interference portions 201a.

The interference portions 201 a are preferably mutually interfering only when the parts 200 place the frame 20 in the use configuration. In addition, they are oriented in such a way that when the user is resting on the support surface 210, the interference portions 201 a provide a mutual interference force proportional to the user’s weight.

In other words, the interference portions 201 a may be shoulders designed to collide when the frame 20 is in use and the parts 200 are arranged in a position of stable equilibrium and the interference force may be the attaching reaction interacting between the interference portions 201 a facing each other.

The parts 200 conveniently achieve the stable equilibrium position thanks to the interference portions 201 a.

In a more complex configuration, the hinges 201 may not be mechanical hinges, for example such as domestic door hinges, but may be hinges 201 designed to allow the parts 200 to be loose with elastic deformation.

In this sense, the parts 200, could even be, as already mentioned, part of a single closed piece designed to be folded in certain fixed loose points. Application examples such as these are present, for example, in bearing-less systems wherein the permitted movements of a hinge can be delegated to deformations of the material instead of to the mechanical connections of the structure.

In addition, the hinges 201 could also involve locking means designed to mutually lock the parts 200, when in use or assembled configuration, so as to ensure that they continue to keep the fabric 21 taut.

Alternatively, the hinges 201 may include an elastic element, such as a spring, designed to keep the parts 200 in use or assembled configuration, if not stressed. In the latter case, the locking means could be configured to lock the parts 200 , and therefore the frame, in the rest or pre-assembly configuration.

Or the interference portions 201 a could, instead, themselves comprise locking means. For example, the latter could include a pressure lockable elastic mechanism designed to lock rotation around the hinge 201 as soon as the interference portions 201 a collide. In addition, this mechanism could allow the release of the parts 200 and the release of the hinges 201 when subjected to pressure again. An example of this type could be a locking mechanism with a spring presser.

The fabric 21 , as mentioned above, is attached to the frame 20 preferably at at least part of its perimetric area 21 1 .

In particular, the frame 20 preferably defines a guide 202.

The guide 202 is preferably a hollow guide that continues along at least each of the parts 200. In particular, the guide 202 preferably basically assumes the shape of a track through which elements, such as rigid elements, compatible with the dimensions of the guide 202, can pass.

Examples of this type are described, for example, in the US-A-2839126 patent application, included herein as a reference, in column 1 lines 62-72 and column 2, lines 1 -12.

In essence, the guide 202 may thus also include access holes that enable objects to be inserted inside the guide 202. These holes may be located, for example, in predetermined points of the frame 20 such as, for example, the fixed points at the ends of parts 200. The access holes are preferably located in the upper area of the frame 20 relative to the ground so that objects can be inserted from top to bottom, as shown in Fig. 8. The access holes preferably face the ground so as to be concealed from a user observing the chair 1 in the use or assembled configuration. The fabric 21 then preferably includes at least one slider 212.

The slider 212 may be defined by a reinforced portion of fabric 21 , or by a portion of fabric 21 of greater thickness and/or density, or it may be defined by an element external to the fabric 21 and attached to the fabric 21 . In any case, the slider 212 is preferably arranged along the perimetric area 21 1 and is designed to be inserted inside the guide 202.

Therefore, the guide 202 is preferably designed to allow the sliding of the slider 212 inside it. In detail, the guide 202 is configured to trap at least part of the slider 212 in order to attach the fabric 21 and the frame 20 together.

The slider 212 can therefore be made continuously along the perimetric area 21 1 of the fabric 21 or the fabric 21 can include a plurality of consecutive sliders 212.

The frame 20 is preferably basically a framework for the fabric 21 inside which the fabric can be placed by sliding the slider 212 into the guide 202. A similar mechanism is also described in the patent application US-B-6293624, included herein as reference, in column 3 lines 26-52.

However, the guide 202 is preferably accessible only from the bottom of the chair 1 , i.e. from the ground, and the fabric 21 is attached to the frame 20 in such a way as to wind around at least part of the frame 20.

In this way, not only is the connection between the frame 20 and the fabric 21 concealed from the user, but in addition the frame 20 itself is covered with the fabric 21 and the tension is further ensured by the winding of the fabric 21 around the frame 20.

The parts 200 may then be different, or they may be identical and mirror each other in relation to the rotation axes 2a.

This last embodiment is preferable especially so as to optimise the production of the parts 200. The latter are, in fact, preferably made of aluminium by means of three- dimensional extrusion. Obviously, the parts 200 could also be made of polymeric material, for example also extruded, or other materials enabling the creation of hollow and continuous profiles with a non-coplanar extension trajectory. In another type of embodiment, the parts 200, and therefore the frame 20, could be made using a composite structure, for example including a metal core covered with a different material, such as a polymeric material, for example by means of technologies such as polymer injection moulding on a metal core.

The non-coplanar nature, however, remains an element that is not necessary, but preferable for making the chair 1 , especially with regard to the comfort provided by it.

The chair 1 also comprises a load-bearing portion 3, in addition to the support portion 2.

The load-bearing portion 3 is preferably designed to bear the support portion 2 suspended and permanently spaced from the ground. For example, a typical load- bearing portion 3 included in conventional chairs is made up of four, or fewer, load- bearing legs.

Otherwise, but not necessarily, the load-bearing portion 3 is preferably made up of a tubular structure that can be connected to the support portion 2. More generally, the load-bearing portion 3 includes attachment means 30.

The attachment means 30 are preferably designed to detachably and stably attach the support portion 2 and the load-bearing portion 3.

These attachment means 30 are preferably interlocking fastenings designed to connect the portions 2, 3 at predetermined fixed points so as to make the chair 1 . More specifically, the frame 20 includes protuberances 22.

The protuberances 22 preferably protrude towards the ground. The protuberances 22 are basically, for example, cylindrical elements that protrude from the frame 20 to interact with other external components.

These protuberances 22 are therefore preferably, in turn, attached to the frame 20 by means of known fastenings such as nails, bolts or other types of joints. Alternatively, the protuberances 22 could be made directly on the frame 20.

The protuberances 22 may, therefore, be made of metallic or, preferably, polymeric material. For example, the protuberances 22 can be made using injection moulding technology.

The attachment means 30 are, then, suitably configured to interact with the protuberances 213. In particular, the attachment means 30 preferably include holes 31 structurally configured to accommodate the protuberances 22 so as to permanently lock the support portion 2 onto the load-bearing portion 3. In particular, the chair 1 is preferably configured in such a way that the weight of the support portion 2 and, possibly, of a body or user placed on it, tends to keep the support portion 2 and the load-bearing portion 3 attached to each other and permanently locked.

The load-bearing portion 3, as mentioned above, does not necessarily define a structure as described above, but may also include a conventional configuration, e.g. cantilevered, four-legged, or other configuration, provided that it includes attachment means 30 designed to allow the coupling of the support portion 2 and the load-bearing portion 3. In an alternative configuration of the chair 1 , the parts 200 may comprise two guides 202 each, as shown in Fig. 9b. In this case, for example, the chair 1 can be configured in such a way as to trap two different fabrics 21 , one of which can be used to make the support portion 2, and the other to cover the bottom of the chair, as explicitly shown in Figs. 10 and 13b. The second guide 202 could also allow the attachment, by interlocking, of a coupling device 5, as shown in Figs. 9b and 13c.

The coupling device 5 could be, for example, a body shell provided on the bottom, in relation to the ground, of the support portion 2 in such a way as to support it, through the attachment in the second guide 202, concealing part of the bottom of the chair 1 , and allowing the support portion 2 to be attached to any type of load- bearing portion 3. In fact, the coupling device 5 could have its own rigidity, for example, thanks to the fact that it is made of a metal or polymer structure, such as to allow the coupling of the support portion 2 to the load-bearing portions 3 such as the wheel supports of typical office chairs, as shown in Fig. 1 1.

As a result, the coupling device 5 may be counter-shaped to the lower portion of the frame 20 and, in particular, may have an edge counter-shaped to the second guide 202 and may be counter-shaped to the final shape of the surface 210 of the fabric 21 of the support portion 2. Obviously, the coupling device 5 may include articulation mechanisms for the support portion 2 known in the state of the art. Mechanisms of this type are known, for example, by the term Synchro-tilt.

The chair 1 preferably comprises, in addition, a tensioner 4.

The tensioner 4 may be part of the load-bearing portion 3 and integrated inside it or it may be an external element.

The tensioner 4 is preferably configured to tension the support surface 210 along predetermined fixed points so that the fabric 21 defines at least two specific areas, or even more. The fabric 21 , when stretched, preferably defines a backrest 21a and a seat 21 b.

The seat 21 a is preferably arranged adjacent to the load-bearing portion 3, while the backrest 21 a is spaced apart from it and is designed to accommodate the user’s back. In particular, the tensioner 4 is designed to exert greater tension on the seat 21 a.

The seat 21 a therefore includes a support surface 210 that is subject to greater tension than, for example, the backrest.

The tensioner 4 preferably includes a tubular element 40.

The tubular element 40 can therefore be hollow or solid. It is preferably U-shaped, or C-shaped, and is designed to exert tension on the support surface 210 along its length.

The support surface 210 can thus be arranged between the tensioner 4 and the ground so that the tensioner 4 tensions the fabric 21 directly towards the ground. The support surface 210 preferably includes a pocket 210a.

The pocket 210a is preferably configured to house at least part of the tubular element 40. In this way, the tubular element 40, when subjected to movements, moves part of the fabric 21 with it.

Depending on the shape of the pocket 210a, moreover, the fabric 21 is also only strained along the attachment points of the tubular element 40 to the pocket 210a or, if the pocket 210a completely covers the tubular element 40, the fabric 21 is strained along the entire length of the tubular element 40.

In this configuration, preferably, the tubular element 40 is arranged below the fabric 21 , with respect to the ground, and inside the pocket 210a made in the fabric, as shown in Fig. 2.

In addition, the load-bearing portion 3 may include second protuberances 32.

The second protuberances 32 are preferably of the same type as the protuberances 22 and basically perform the same function.

In fact, the second protuberances 32 are preferably housed inside the tubular element 40 and the latter is thus configured to house them.

In addition, the load-bearing portion 3 includes attachment means 33.

The attachment means 33 are preferably configured to lock the tubular element 40 in a predetermined position towards the ground, wherein the tensioner 4 subjects the support surface 210 to continuous tension.

Conveniently, the attachment means 33 are substantially interlocking means designed to trap at least part of the tensioner 4 in such a way that it can remain permanently arranged in a predetermined position, exerting its action in a continuous manner, as mentioned.

In detail, the tensioner 4 can also define a curvature, or concavity towards the ground. The latter can, in fact, facilitate the coupling between the attachment means 33 maximising their stability given that the tensioner 4, once the user has sat on the support portion 2, exerts a force consistent with the locking direction of the attachment means 33.

The production of the support portion 2, and in particular the seat 21 b and backrest 21 a, is mainly obtained thanks to the tensioner 4. However, the configurations of the frame 20 and fabric 21 also contribute significantly to the technical aspects of the support portion 2, for example, thanks to the different stiffness that the fabric 21 can have, also thanks in part to the shape of the frame 20.

As mentioned, the production technique of the fabric 21 , by means of machine knitting, enables the density and conformation of the fabric 21 to be controlled locally.

In addition, the shape of the frame 20 can enable, and preferably does enable, the fabric 21 to be subjected to different tensions along its perimetric area 21 1 .

In particular, the frame 20 assumes a preferably three-dimensional eight shape with the portion reserved for the seat 21 b being wider than the portion reserved for the backrest 21 a.

In this way, a priori, the fabric 21 is tensioned more in the area reserved for the seat 21 b. As a result, it is possible to synergistically combine the technological possibilities provided by the fabric 21 , frame 20, and tensioner 4, so as to define a support surface 210 controlled in each sector.

For example, the seat 21 b is, conveniently, stiffer than the backrest 21 a and is, therefore, less deformable.

The operation of the chair 1 described above in structural terms is basically defined by the procedure for its construction, described below.

The construction procedure comprises a plurality of successive steps, that enable the chair 1 to be made from the individual parts. However, the most important step is the tensioning step. In fact, during the tensioning step, the parts 200 are preferably rotated reciprocally with respect to the rotation axes 2a in such a way as to create the frame 20 and tension the fabric 21 .

This tensioning step is innovative in that it enables the support portion 2 to be made without any difficulty and guarantees the correct tensioning of the same in order to make the chair 1 .

In addition, the tensioning step can be preceded by an installation step wherein the fabric 21 is attached to the frame 20. In particular, the slider(s) 212 of the surface 210 are preferably inserted inside the guides 202 of the parts, for example through a specially cut slit at the ends of the parts 200, and the fabric 21 is then attached at the perimetric area 21 1 to the frame 20.

Aside from the above steps, the process includes other relevant steps that may complement or replace the previous step.

For example, a preferred manufacturing process of the chair 1 , may include a support portion 2 defined in the tensioning step and possibly the installation step. Alternatively, the manufacturing process may include a support portion 2 including, initially, the frame 20 and the fabric 21 properly attached to each other with the tensioned fabric 21 .

The procedure may then comprise an attachment step in which the load-bearing portion 3 and the support portion 2 are attached to each other.

In particular, the attachment step consists of inserting the protuberances 22 inside the holes 31 of the attachment means 30.

In addition, the process may advantageously comprise an additional shaping step wherein the tensioner 4 is attached to the support portion 2 and to the load-bearing portion 3 and tensions the surface 210.

More specifically, the tubular element 40 of the tensioner 4 is preferably inserted inside the pocket 210a made on the surface 210 and is then attached by inserting the second protuberances 32 inside the ends of it.

Once the tensioner 4 is attached to both portions 2, 3 it is preferably brought close to the ground and locked by the attachment means 33 that enable the tubular element 40, and thus the tensioner 4, to be kept in a position such that the fabric 21 is tensioned at predetermined points,

As a result, the shaping of the chair 1 enables the backrest 21 a and the seat 21 b of the chair 1 to be defined.

As already mentioned, the insert 100 can be part of the modular chair 1 as described above, or it can be designed for other chairs.

In any case, the insert 100 preferably comprises a support structure 101.

The support structure 101 is preferably designed to enable the attachment of the insert 100 to an external support 105.

The external support 105 can be any type of body designed to enable the firm attachment of the insert 100. It can, therefore, be, for example, a tubular element, for example one belonging to the frame of a chair. In this sense, the external support 105 can preferably coincide with the frame 20.

The support structure 101 , in addition, preferably defines a main extension direction

101a

The main extension direction 101 a is preferably the direction along which the support structure 101 extends. In addition, the main extension direction 101 a is preferably the direction along which the support structure 101 is attached to the external support 105.

The support structure 101 preferably includes, therefore, a coupling zone 102 and a joining zone 103.

The coupling zone 102 is the zone immediately designed to enable the attachment with one or more external supports 105, while the joining zone 103 is preferably designed to enable the joining or attachment of the support structure 101 to at least one external body 104. Of course, the joining zone 103 could enable the joining of the support structure 101 with a plurality of external bodies 104, just like the coupling zone could enable the coupling with a plurality of external supports 105, such as, for example, shown in Figs. 20a and 20b.

The external body 104 is preferably any external element that can be joined to the joining zone 103. The external body 104 is preferably an element that contributes to the covering of a chair, for example like the modular chair 1 , and can include useful elements in this sense, such as fabric, padding, or a solid body, such as a body shell.

The external body 104 is preferably one or more of either: fabric, padding, or a solid body.

The insert 100, therefore, preferably comprises, when in use, both the support structure 101 and the external body 104.

The coupling zone 102 preferably defines an open tubular element extending along the main extension direction 101 a. The open tubular element is basically a tube comprising at least one hole that extends along the main extension direction 101 a. For example, if the tubular element is a crossbeam with thin walls, the coupling zone 102 is a crossbeam with thin walls with an open section.

The coupling zone 102 therefore basically defines an open profile that defines a perimetric section 102b and a perforated section 102c.

The open profile is preferably the shape created by the section of the coupling zone compared to a plane perpendicular to the main extension direction 101 a.

The perimetric section 102b corresponds, thus, basically to the part of the profile created by the walls of the coupling zone 102, while the perforated section corresponds to the free portion of the profile.

In particular, the perforated section 102c preferably corresponds to less than 35% compared to the perimetric section 102b.

In this way, the coupling zone 102 basically creates a hook for the support structure 101 .

The joining zone 103, in contrast, preferably defines a flat surface extending along the main extension direction 101 a.

The coupling zone 102 is preferably basically circular and, therefore, the support structure 101 basically creates, as a whole, a question mark or hook shape.

The joining zone 103, in this embodiment, is immediately adjacent to the perforated section 102c, but could also not be. For example, the joining zone 103 could be attached to the perimetric section 102b, far from the perforated section 102c.

In any case, as mentioned, the joining zone 103 is configured to enable the insert 100 to be joined to the external body 104.

In this respect, the joining zone 103 can preferably comprise various joining elements while yet remaining within the same inventive concept. For example, the joining zone may comprise eyelets designed to accommodate interlocking elements, such as buttons, or it can include buttons itself, or it can include an adhesive portion, with velcro, glue, or the like.

The joining zone 103 is preferably a portion that is thin enough to be perforated and can enable a fabric to be sewn onto it.

The support structure 101 therefore comprises at least one joining zone 103; in any case, it could also include two joining zones 103.

In this alternative embodiment, the joining zones 103 are preferably separated from each other by the perforated section 102c and attached to the opposite ends of the perimetric section 102b respectively.

In this way, the coupling zone 102 can easily house any external support 105, by introducing the latter between the joining zones 103.

In fact, the whole support structure 101 is preferably made of a single piece and includes flexible material. Even more specifically, the support structure 101 includes polymeric material that can be deformed, like rubber. The deformation of the support structure 101 can be exclusively elastic, or it can be partially elastic or plastic, or the support structure 101 could be an element that is wholly, plastically deformable in such a way as to enable its deformation to be maintained and its being shaped as desired, for example, counter-shaping the coupling zone 102 to the external support 105.

The coupling zone 102 advantageously comprises a plurality of first notches 102a. The first notches 102a are through holes arranged on the surface of the coupling zone. The notches, therefore, are basically, preferably, arranged in the coupling zone 102 at the perimetric sections 102b.

The notches 102a are, in fact, preferably perimetric and extend along planes perpendicular to the main extension direction 101 a.

In this way, the first notches 102a are produced to enable the deformation, preferably elastic, of at least part of the support structure 101 and at least the curvature of at least part of the main extension direction 101 a. Even more specifically, the notches 102a enable at least part of the support structure 101 to be easily bent, mainly at the coupling zone 102.

Therefore, the first notches 102a preferably extend along at least 70% of the perimetric section 102b locally defined by the profile of the section defined by the corresponding plane in the coupling zone 102.

In this respect, the joining zone 103 also preferably comprises a plurality of second notches 103a.

The second notches 103a also preferably extend along planes perpendicular to the main extension direction 101 a in such a way as to enable the deformation, preferably elastic, of at least part of the support structure 101 and at least the curvature of at least part of the main extension direction 101 a.

Specifically, the second notches 103a preferably enable the bending, mainly of the joining zone 103.

In addition, the first notches 102a and the second notches 103a are preferably arranged on the corresponding planes.

In addition, both the first notches 102a and the second notches 103a can define different shapes. For example, they can define basically straight shapes and define, therefore, straight through-holes along the perimetric section 102b and along the flat surface defined by the joining zone 3.

Or, each of the notches 102a, 103a can define an isosceles triangle shape wherein the vertex of the isosceles triangle is turned towards the joining zone 103 and towards the coupling zone 102, respectively.

The first notches 102a are preferably straight, while the second notches 103 create a triangle shape.

The insert 100 can, thus, be used in different configurations.

For example, the insert 100 can be inserted into a chair like the modular chair 1 . The chair 1 can, therefore, essentially comprise the insert 100 and the frame 20 where the frame 20 can simply just defined a tubular element.

In this case, therefore, the external support 105 of the insert 100 corresponds to the frame 20. In use, the coupling zone 102 can trap the frame 20 and the support structure 101 is shaped to the frame 20 by locally varying the main extension direction 101 a if the frame 20 is not straight. Basically, therefore, the deformability of the insert 100 easily enables it to be adapted to any frame 20, for example frames with complex shapes such as that of the chair 1.

In addition, the fact of defining a coupling zone 102 with the above-mentioned proportions and a material that can be deformed enables the frames 20, with normal diameters or sections of different sizes, to be trapped.

As already mentioned, in fact, the insert 100 is preferably made of a deformable material, for example, but not exclusively, polymer. In addition, it is preferably made of a single piece, but could also be made of more pieces joined together.

In a preferred use configuration, the chair 1 comprises a frame 20 that includes some of the features described above. Basically, for example, the frame 20 defines at least one guide 202, the fabric 21 includes at least one slider 212 designed to be trapped inside the guide 202. The guide 202 is, thus, configured to trap at least part of the slider 212 in order to attach the fabric 21 and the frame 20 together, as already described. In any case, in addition, the guide 202 is configured to trap the coupling zone 102 of the insert 100 in order to attach the insert 100 and the frame 20 together. In addition, the coupling zone 102 advantageously traps, in turn, the slider 212.

In this way, the guide 202 creates a block able to firmly attach, at the same time, both a fabric 21 and an external body 104.

This feature is fundamentally important when it comes to assembling the fabric on the chair 1 . For example, the assembly can consist in joining functional parts of the chair 1 or even in a simple covering.

In fact, the insert 100 enables the implementation of a special procedure for assembling the chair 1.

The assembly procedure may be basically a simple assembly procedure or may basically be a procedure for covering the chair 1 .

In particular, the assembly procedure, or covering procedure, comprises at least the coupling steps and insertion steps in order to create the structure described above. In the coupling step, the slider 212 is preferably trapped inside the coupling zone 102 in such a way as to attach the insert 100 together with the fabric 21 .

In addition, in the insertion step, the coupling zone 102 is inserted into the guide 202 in such a way as to attach the insert 100 and the frame 20 together so that the chair 1 is at least partially covered both with the external body 104 and with the fabric 21 . The external body 104 can, therefore, be a body shell, or an additional fabric or a padding hidden by the fabric 21.

The insert 100 according to the invention achieves important advantages.

In fact, the insert 100 can easily be inserted on or inside frames and, therefore, makes it possible to significantly widen the possibilities for composing the chair on which it is installed. In fact, the insert 100 provides the possibility of adding an additional level of functionality to the existing method for attaching the primary fabric 21 that constitutes the seat surface and the area of the backrest of the chair, like the chair 1.

This, in practice, enables a backrest with knitted padding to be easily created with performance features deriving from the overlapping of one conventional knitted fabric in a padded or flat configuration and a secondary layer of a mesh.

The insert 100 therefore enables the precise control of the tension of the fibre or of the fabric itself via a precise attachment of the fabric and the possibility of also varying the tension, to which the supported portion of fibre or fabric is subjected, in order to obtain a superior level of comfort.

In addition, in enabling the above-mentioned implementations, for example via the insertion of external bodies 104, the insert 100 avoids the execution of additional processes on the chair or the need to complete special joining operations.

As a result of these advantages, an additional advantage offered by the insert 100 is that it allows a quick and simple assembly of the external body 104 on the chair 1 .

The shape of the insert 100, furthermore, makes the same very easy to produce with reduced costs.

Variations may be made to the invention that fall within the scope of the inventive concept defined in the claims.

For example, the system of attaching the fabric 21 and the frame 20 could be different and could involve a non-detachable attachment between the two. In addition, the guide 202 could be designed to house a plurality of adjacent sliders 212, as shown in Fig. 9a; therefore, the frame 20 could be operationally connected and attached to a plurality of fabrics 21 , for example, overlapping.

The insert 100 could, thus, also comprise an intermediate portion 106.

The intermediate portion 106 could be, for example, arranged between the coupling zone 102 and the joining zone 103. It could also be a part of the joining zone 103, not including second notches 103a.

In addition, the intermediate portion 106 is preferably a plastically deformable portion. To achieve this deformation, the intermediate portion 106 could comprise grooves designed to reduce the local thickness of the support structure 102, while increasing flexibility, and a plastic core, such as a thin metal. Of course, it is possible to use any material that enables the plastic deformation in such a way as to change the orientation of the joining zone 103 with respect to the coupling zone.

In this context, all details can be replaced by equivalent elements, and the materials, shapes, and dimensions may be any materials, shapes, and dimensions.