The present invention relates to a metallic frame for chairs with tubular elements.

Chairs with welded tubular elements are currently widespread which are of the type comprising two inverted U-shaped elements that form the legs, two L-shaped elements that form a support for the back and the seat, and two horizontal and mutually parallel rod-like crossmembers that join the inverted U-shaped elements and the L-shaped elements.

These elements are often joined by gas welding with the addition of material, and this entails rather long times to be dedicated to the assembly of the chairs and the consumption of added material for welding, as well as associated high costs.

A solution aiming at overcoming these drawbacks is proposed with the teaching contained in WO02054913 in the name of this same Applicant. This application proposes to replace welding with added material with welding of the projection type, thus reducing production costs and times in addition to reducing the weight of the frame, facilitating therefore its movement and transport. According to the teachings of the patent, the projection welding is performed advantageously at pairs of raised portions formed by recesses of the cross-section of the tubular elements.

However, since market demand for this kind of chair is rather high, the number of components to be assembled affects heavily the final production costs and the need is felt, therefore, to reduce these costs further and to also reduce further the production times, trying nonetheless to obtain a frame whose solidity is comparable to the preceding ones.

This type of structure is also designed so that it can be stacked easily for storage and transport on pallets.

The possibility of vertical stacking is achieved by superimposing the frames and alternating them turned by 90° with respect to each other. Currently, the need is also felt to increase the number of stacked chairs that can be transported, i.e., to increase their total number that can be carried within the same volume of a pallet in order to reduce the associated transport costs.

Another drawback is due to the fact that the inverted U-shaped elements, which constitute the legs of the chair for resting the frame on the floor, due to their very shape and to the distance between the front legs and the rear legs, are unable to ensure stable resting even when the chair is in use, i.e., to exclude the risk of tipping, because the back typically protrudes from the rear part of the chair with respect to the rear legs.

The aim of the present invention is to provide a metallic frame for chairs with tubular elements that is lighter than known frames and therefore can be handled more easily by a user and, when stacked with other identical frames, occupies with them a smaller volume than known frames.

Within this aim, an object of the invention is to provide a frame that is at least as solid as currently commercially available frames and that in particular is not subject to tipping problems.

Another object of the invention is to reduce the transport costs of frames for chairs with tubular elements.

Another object of the invention is to obtain a chair that has a different visual impact than known chairs.

This aim, as well as these and other objects which will become more apparent hereinafter, are achieved by a metallic frame for chairs with tubular elements, characterized in that it comprises two inverted V-shaped elements that form the legs of a chair, which are parallel and joined substantially at their inside curvature to a rodlike crossmember, two L-shaped elements connected by said crossmember on which they are arranged in a parallel configuration so as to form a support for the back and for the seat, respectively with their first portions, which are substantially vertical, and second portions, which are substantially horizontal.

Further characteristics and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of the frame according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view of a frame according to the invention; Figure 2 is an enlarged-scale view of a detail of the frame of Figure 1 ;

Figure 3 is a view of a detail of a portion of an L-shaped element;

Figure 4 is an enlarged-scale view of a detail of a portion of an inverted V-shaped element;

Figure 5 is an enlarged-scale view of another detail of another portion of an inverted V-shaped element;

Figure 6 is a side view of the frame according to the invention;

Figure 7 is a front view of the frame according to the invention;

Figure 8 is a top view of the frame according to the invention;

Figure 9 is a perspective view of two frames according to the invention, stacked vertically according to a first stacking method;

Figure 10 is a perspective view of a column of frames according to the invention, stacked vertically with a second stacking method;

Figure 1 1 is a top view of four columns of frames stacked according to the method of Figure 10.

With reference to the cited figures, the frame, generally designated by the reference numeral 10, is formed by tubular elements 1 1 , the mutual association of which is provided by welding.

The frame 10 as a whole is shown in Figure 1. It comprises two inverted V-shaped elements 12, which form the legs of the chair, and two L- shaped elements 13, which form a support for the back and the seat.

The two inverted V-shaped elements 12 are parallel and are joined substantially at their inside curvature 14, shown in detail in Figure 4, to a rodlike crossmember 15. The L-shaped elements 13 are connected by the crossmember 15 and are joined to it again by welding and are arranged thereon in a parallel configuration. In particular, they form a support for the back with their first portions 16, which are substantially vertical, and form a support for the seat with their second portions 17, which are substantially horizontal and mutually parallel.

Figure 2 is an enlarged-scale view of the frame on the joining regions of an inverted V-shaped element 12 and of an L-shaped element to the crossmember 15.

Each one of the inverted V-shaped elements 12 has a first pair of raised portions 18, at the inside curvature 14, which is formed by a corresponding first recess 19 of the cross-section obtained with a plastic compression deformation. Said first recess 19 is provided so that upon V- shaped bending the excess material does not form wrinkles in the region of the inside curvature 14.

The first pair of raised portions 18 and the first recess 19 are visible in the enlarged-scale view of Figure 4. Joining by welding occurs in the regions of contact of the first pair of raised portions 18 with the crossmember 15, which consist of at least four points, but welding can extend, depending on the shape of the inside curvature 14 and of the crossmember 15, up to one or two parallel lines that correspond to the two raised portions.

Each one of the L-shaped elements 13 advantageously has a second pair of raised portions 20, formed by a corresponding second recess 21 on the lower side of the second portion 17 and so as to correspond to the region for joining to the crossmember 15. The second pair of raised portions 20 is also provided specifically by plastic compression deformation and produces a localized contact region at which welding with the crossmember 15 occurs.

Advantageously, each one of the L-shaped elements 13 also has an additional pair of raised portions 22 at the curvature region 23, which are formed by an additional recess 24 that is also obtained by plastic compression deformation, again to prevent that, as a consequence of the bending, the curvature region 23 of the L-shaped element 13 has wrinkles caused by an excess of material in the regions having a smaller radius.

The first portions 16 and the second portions 17 of the L-shaped elements conveniently have a flattened cross-section, in order to give the back and the seat a larger contact surface, and it can be noted, in particular from the perspective view shown in Figure 1 and from the top view of Figure 8, that the first supporting portions 16 of the back are also rotated, adapting to the curvature of the back to be associated with the frame in order to compose the chair.

The crossmember 15 has an oval cross-section that can be seen clearly in Figure 5, with, in a sectional view, parallel sides 25, joined by semicircular elements 26, which form two parallel faces of the same crossmember 15. Joining by welding with each one of the inverted V- shaped elements 12 and with each one of the L-shaped elements 13 occurs at the uppermost face of the two parallel faces.

The L-shaped elements 13 are joined by welding along at least one raised portion of the second pair of raised portions 20.

As can be seen in Figure 1 and in particular in the front view of Figure 7, the crossmember 15 is substantially rectilinear and therefore the welding of each one of the L-shaped elements 13 occurs at two parallel lines that are formed by the respective second pair of raised portions 20, which are intended for contact with the crossmember 15. However, if the crossmember 15 is not rectilinear but has for example a curvature or a bend in a downward direction that is contoured to the shape of the seat, the weld might still be performed validly in the same regions or along a single raised portion of the second pair of raised portions 20.

It should be noted that the oval cross-section of the crossmember 15 allows welding the elements on larger regions of contact than in the case of the crossmember with circular cross-section as in known frames, making the weld more effective and durable.

Conveniently, as can be seen in the enlarged-scale view of Figure 5, each inverted V-shaped element 12 has a reinforcement recess 27 on the inner part of each one of the two rectilinear portions 28 that form respectively a front leg 29 and a rear leg 30 of the chair.

The reinforcement recess 27, as is clearly visible, extends practically along the entire length of the leg and becomes gradually shallower in an upward direction. As shown in Figure 9, in the stacking of the frames 10 the internal surface of the rectilinear portion 28 of each front leg 29a or rear leg 30a of a frame 10a is coupled to the outer surface of the underlying leg, respectively the front leg 29b or the rear leg 30b, of the underlying frame 10b.

By way of non-limiting example, an angular aperture of the inverted V-shaped elements 12 of approximately 52° is to be preferred; an angle of approximately 109° between the first portion 16 and the second portion 17 is instead to be preferred, again merely by way of example, for the inclination of the L-shaped elements 13.

With these solutions, the front legs 29 and the rear legs 30 of the frame 10 form, with their four resting points 33 at the base, a resting area 34, shown in broken lines in Figure 1 , within which every point of the L- shaped elements 13 lies.

Once the back is assembled, the back fitted on the L-shaped elements 13 also is such that every point thereof lies within the resting area 34. These refinements allow producing a chair that is capable of passing any tipping prevention tests.

Each L-shaped element 13 is provided conveniently, at its second portion 17, with a hole 31 for fixing the seat of the chair by means of screws. The back can be associated easily with the frame 10, for example by making it slide from above onto the two first portions 16, so that they enter adapted guides in said back. The use of the frame according to the invention, in its stacking with other similar structures, is as follows.

The frame 10 can be stacked according to two possible stacking methods.

The first method is shown in Figure 9 and the resulting configuration is designated by the reference letter A to distinguish it from a different configuration of stacked frames 10, which can be obtained with a second method shown in the subsequent Figures 10 and 1 1 and is designated here by the reference letter B.

With the first stacking method, the frames 10 are superimposed vertically on each other according to the same orientation.

The inverted V-shaped elements 12 are inserted into each other and the reinforcement recesses 27, which make the internal surface of the rectilinear portion 28 of each front leg 29a or rear leg 30a mate with the outer surface of the underlying leg, respectively the front leg 29b or the rear leg 30b, ensure stable and aligned stacking of the frames 10. With the second stacking method, the frames 10, other than with the preceding method, are superimposed vertically so that they are alternated with an orientation of 90° of one with respect to the following one. The stability of the stack of frames 10 is determined by the coupling of the internal surface of each front leg 29a or rear leg 30a of the frame 10a with the external surface of the underlying leg, the front one 29b or the rear one 30b, which is the leg of the frame 10b that is arranged with the same orientation and is spaced from the upper frame 10a by an intermediate frame 10a that is rotated by 90°.

By repeating the stacking for a larger number of frames 10, one obtains the column 32 of frames 10 shown in Figure 10.

By grouping four columns 32 of frames 10 stacked according to the configuration B described above it is possible to fill a pallet without wasting space, as shown in Figure 1 1. By way of example, it has been found that a pallet with maximum external dimensions of 1 15 cm x 1 10 cm x 235 cm can contain 56% more frames 10 than the traditional product.

It should be noted that with respect to known frames, since the legs are formed by an inverted V-shaped element 12 with flattened regions produced by reinforcement recesses 27 on the internal part over the entire length of the legs 29 and 30, the line of the frame 10 is slenderer, as can be seen in particular in the side view of Figure 6, and is aesthetically new with respect to known chairs with U-shaped elements. At the same time, again thanks to the reinforcement recesses 27, the frame 10 is also stronger and the stacking possibility is improved.

Moreover, the presence of a single crossmember 15 having an oval cross-section allows not only welding the components at larger regions of contact than would be the case with a circular cross-section, but also makes it possible to save material and to obtain a frame that is lighter and therefore easier to handle and transport than a frame provided with two crossmembers.

The difference in weight of course becomes more evident when the frames are stacked and grouped in large numbers in pallets for transport.

In practice it has been found that the invention achieves the intended aim and objects, providing a metallic frame for chairs with tubular elements that is lighter than known frames and therefore can be handled more easily and allows reducing and containing production times as well as production and transport costs.

The cost reduction in fact arises from the smaller amount of material to be used to provide the frame and from better utilization of the volume of the pallet by insertion of a larger number of frames therein.

Moreover, the frame is stable both when in use, provided with a seat and a back, passing anti-tipping tests, and when stacked with other identical frames, according to both configurations A and B. Moreover, the frame has a different visual impact than traditional ones.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application no. PD2013A000084, from which this application claims priority, are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.