Background Art In prior art one knows many types of demountable frame chairs in wood for reducing to minimum dimension both in store and for packing and transportation.

Main drawbacks of current solutions a-effective minimum dimension of the dismounted packing; b-variability of the final shape according to specific needs of the consumer; c-difficult or complex assembly and, if any, disassembly; d-quick assembly; e-solidity and safety of the assembly in time; f-life of the chair.

The characteristic (e) results the most weak because it is well known that the demountable chairs easily loosen in use, making them therefore unusable because they become tottering and unsafe.

Aim of this invention The aim of this invention and the problem to be solved is to supply a maximum performance to the aforementioned characteristics: a, b, c, d, e, f in a suitable balancing of the combination.

Essence of the invention The purpose is reached and the problem is solved with the characteristics of the main claim.

The characteristics of the subclaims represent preferred solutions which are not limitative.

In this way the maximum performance of the aforementioned characteristics in a harmonic balancing is obtained: a, b, c, d, e, f And above all maximum reliability of the assembly to persist in time, thanks to the possibility, in case of slackness in the use, always to be able to effectively clasp the respective assembly tie-rods.

An additional advantage consists in the reduction of working costs with greater quality of the product and possibility of varying it simply by changing the seat.

Detailed description of a solution Below a preferred realization mode of the invention is described with the aid of included drawings, wherein: - Fig. 1 represents a partial side view of the mounted chair at the height of the seat-under-the-seat zone that constitutes the assembly-plane-zone.

- Fig. 2 represents a plan view of the chair at the height of the frame under the seat which concerns the assembly-plane-zone.

- Fig. 3 represents a perspective view from inside a corner of the frame under the seat which concerns the assembly zone without respective ironware-connecting-means.

- Fig. 4 represents the same view of Fig. 3 with the respective assembly ironware-connecting-means.

- Fig. 5 represents a longitudinal sectional view of the screwing system for diagonally tensioning tie-rods between opposite angle crossbeams for clamping the shank (front or back) between them.

- Fig. 6 represents the separated perspective drawing of the flanged tension buckle which is internally threaded and has a shoulder at

one side with one of two semi-tie-rods having a flanged head for the insertion from inside into said flanged buckle with free rotation.

Fig. 7 represents in perspective drawing the two elements of Fig. 6 assembled, namely the flanged semi-tie-rod within the flanged buckle.

Fig. 8 represents in perspective drawing the tie-rod completely mounted by screwing the threaded semi-tie-rod into the said flanged buckle.

As disclosed by the figures above, the chair is composed of: - two front legs (1); two back legs (2) that protract upwards to realize also a back supporting construction for many variations (not illustrated of known art); four crossbeams under the seat (3) whose heads fit by corner- head-engagement with a known art peg (p), transversely within said legs (1,2), and involving: two internal vertical transverse opposite holings (f) near said corner-head-engagement (p) and corresponding internal receding slots (i) penetrating transversely horizontally beyond said holes (f); three milled seats (ii) situated horizontally on the length of the crossbeams; - four tie-rods (4) made up of two semi-tie-rods (41.42) that are connected between them by a tension buckle by screwing (43), being the opposed ends of said holed tie-rods (410,420) ; eight pegs (5) for inserting within said holes (f) of said crossbeams of the frame under the seat (3) with contemporary

insertion into said holes (410,420), after their fit within said internal slots (1) inside the said crossbeams (3) that, if assembled, form the frame under the seat, as said tie-rods (4) are placed according to an axis substantially at 45° forming with the crossbeams (3) a triangle whose top is the leg, whose sides are the crossbeams (3) and the tie-rod forms the base (4); - a seat (32) that is made to fit over said frame under the seat by engagement by opposite internal dowels (31) centrally arranged as to the crossbeams and housed in a suitable seat (ii) and subsequently screwed under the seat (32).

In that way a solid assembly of the chair is obtained and one can vary its exterior shape as one likes varying either the seat or the back or the form of the legs.

Advantageously: - said tension buckle for screwing (43) is flanged internally (430) and it is threaded internally ; - a first semi-tie-rod (41) is inserted within it and presents a head flange for rotation and seal (411); - a second semi-tie-rod (42) has a threaded screwing head (421) for screwing within said flange (43).

In that way the pulling system is more simple and effective and the tension buckle (43) can be screwed for better clamping at any time in case of slackness, always maintaining the chair assembled with the maximum solidity.