Technical Field The invention consists of a profile formed by the union of four elements; it is validly used in the field of window and door frames.

Background Art The technique of connecting aluminium profiles and wood fillets aimed at forming window and door frames has been known for some time now. The metallic profile constitutes the outer part of the frame, while the wood makes its inner part. Thus, the weather resistance and waterproof properties of aluminium and the beauty and thermal insulating properties of wood are all exploited.

Metal can be coupled with wood by means of a bonding resin, which is percolated in the space present between these materials. Yet, more recently, the method of coupling these materials by means of an intermediate plastic profile spread.

For instance, the International Patent filed with no. PCT/EP92/02105 is well known. In this invention, the plastic profile has wings converging towards the outer part of the frame, and fit with corresponding wings created on the wall heading towards the inner part of the frame of the outer metallic profile. In detail, the fitting takes place between a rib created on the radial internal wall of each metallic wing and a complementary groove created on the radial outer wall of the plastic wing. Other metallic wings can be present between the above mentioned plastic wings with the function of maintaining the latter in pretensioning during coupling. The intermediate plastic profile is equipped, on the opposite side of the one in which the above mentioned wings are positioned, with at least one rib which fits in a corresponding groove created in the wood element on the wall converging towards the external part of the frame.

The International Patent filed with no. PCT/EP94/01273 describes an

interconnected profile in which, between the metal profile and the plastic profile, there is an anchorage enabling a sliding movement in a longitudinal and transversal sense between these two profiles. This anchorage is obtained by the union of the external elements of shear joint of the plastic profile and those of the metal profile and between the internal elements of joint of the two profiles constituted by two return flanges of the plastic profile and a corresponding number of flanges of the metal profile. These are equipped with a convex surface or with an angle-bent surface. The return flanges of the plastic profile, used to restore the interconnected elements after a transversal movement, are deformed during the assembling stage so that they press against the flanges of the metal profile.

Even though they do not deny the validity of the above mentioned inventions, it has to be considerated the fact that the movements between the intermediate plastic profile and the wood fillet are extremely limited. Yet it is well known that, in case of a thermal shock, since the plastic material and wood have a different dilation, the frame formed in this way can undergo permanent deformations.

The ribs of the plastic profile, in both Patents, are pushed with strength in the grooves of the wood fillet. In order to ease this operation a certain tolerance between these elements is envisaged. Yet, in the minimum space that is therein created, water and air can infiltrate with the consequence of the deterioration of wood, caused by humidity, fungus, mildew etc.

Furthermore, the screws fixing the accessories of movement of each sash are fixed onto the metal profile of the sash itself, directly or after having drilled the plastic profile. The screws therefore constitute as many thermal bridges which transmit heat from the outside towards the inside of the metal profile causing condensate or even the formation of dew.

Disclosure of Invention Aim of the invention is that of creating a several elements profile that, thanks to its building characteristics, does not undergo the above mentioned

problems.

These as well as other aims are met by the profile for the production of window and door frames as in object, which is obtained by the combination of a outer metal profile, by a plastic material profile, by a bonding resin layer and by an inner wood fillet.

The plastic profile is equipped with two wings converging towards the outer part of the frame, which radially embrace the metal profile and slide on it until they meet two wings made on the radial walls of the metal profile itself. The end of each wing of the metal profile converging towards the outer part of the frame shows a support pin which is equipped with a rib converging towards the radial parts of the metal profile. On each radial wall of the latter profile, starting from the metal wing, a groove is obtained, having an edge at its end facing the plastic profile.

When the support pins of the wings of the plastic profile face these grooves, the wings of the metal profile are chamfered and press on the support pins, forcing the relevant ribs to enter in the grooves. A trip shear between the two profiles is thus obtained. This shear, even granting that the two profiles cannot detach one from the other, enables the longitudinal sliding of a profile as compared to the other.

The metal profile of each sash shows the wall facing the inner part of the frame moulded in such a way that, after the coupling of the metal profile with the plastic profile, between the two a chamber is formed. Its extension is sufficient to handle the screws fixing the accessories of movement of the sash itself.

On the wall facing the wood fillet, the plastic profile has at least two more wings. One of these at least is on an edge based on the side of connection with the wood fillet to carry out the double function of constant fixed spacer of the wood fillet from the plastic profile and of acting as a container of the bonding resin percolated.

At least two wings of the wall of the plastic profile facing the wood fillet have

the ends hook-bent so that between them and the named wall of the plastic profile some channels, facing one another, are created.

At least one wing of the plastic profile facing the wood fillet is prolonged with an arm having the function of hooking the wood fillet or, in the case of the jamb, having the function of embracing its radial outer wall, partially protecting it against weather.

On the wood fillet wall facing the outer part of the frame some slots are created, preferably moulded in dovetail profile.

In the dead bottom channel existing between the plastic profile and the wood fillet the resin is injected. The resin fixes on the wood fillet. The above mentioned slots created on the wood fillet enable the resin to increase the support surface and therefore to increase the cohesion of the resin itself with wood. The resin also covers the surface of the plastic profile facing the inner part of the frame but it does not fix on the plastic profile. The hook-shaped wings of the plastic profile, though, give way to crashes that avoid the resin to detach from the plastic profile, only enabling it to longitudinally slide with respect to it.

The so formed profile therefore enables a double longitudinal inner sliding : between the resin and the plastic profile and between the latter and the metal profile. This enables the maximum balance to thermal dilations.

The resin completely fills the slots of the wood fillet and melts with it thus strengthening the structure of the frame. The outer wall of the wood fillet is this way protected from water and air.

The screws fixing the accessories of movement of each sash are fixed to the plastic profile and are housed in the channel existing between the latter and the metal profile. Therefore the screws no longer constitute sources of conduction of the external temperature towards the inside of the metal profile.

The metal is completely isolated from the wood because between the two profiles constituted by these two materials the plastic profile and the resin

are interposed. There is no contact between metal and wood.

The shear system between the wings of the plastic profile and those of the metal profile, thanks to the shape of the parts in contact, is extremely safe and avoid the possible detachment of the parts even though the pressure of the metal chamfered wings reduces (because of their flexibility) on the hooking pins.

Brief Description of Drawings The present invention is hereinafter further clarified with reference to the enclosed sheets of drawings in which: Figure 1 shows a transversal cross section of a sash of a frame according to the invention; Figure 2 shows a transversal cross section of a jamb of the same window frame; Figures 3 and 4 show the transversal cross section of the metal profiles used; Figures 5 and 6 show the transversal cross section of the plastic profiles used; Figure 7 shows, in more details, the transversal cross section of one of the hooking area between the metal profile and the plastic profile.

Best Mode for Carrying Out the Invention In more detail, and with reference to the enclosed drawings, the profile for the production of window and door frames as in subject is obtained with the combination of an outer metal profile 1,2, of a plastic profile 3,4, of a bonding resin layer 5 and of an inner wood fillet 6,7.

The plastic profile 3,4 is equipped with two wings 8,9 converging towards the outer part of the frame that embrace the metal profile 1,2 and slide on it until they meet the basis of two wings 10,11 created on the radial walls of the metal profile 1,2 itself. The distal end of each wing 8,9 of the plastic profile 3,4 is constituted by a support pin 12 which is moulded in such a way that it shows a rib 13 facing the metal profile 1,2. In correspondence of this

rib 13 on the metal profile 1,2 a groove 14 is envisaged.

The wings 10,11 of the metal profile 1,2 are chamfered once the wings 8,9 of the plastic profile 3,4 are in place, which is to say when the support pins 12 face the grooves 14. The chamfered metal wings 10,11 compress the support pins 12 of the wings 8,9 of the plastic profile 3,4 thus pushing the ribs 13 inside the grooves 14. The tooth existing on the vicinal end of each rib 13 is therefore fixed against the edge of the corresponding groove 14.

Even though the flexibility of the metal wings 10,11 tends to make them go back to their original position, the rib 13 of each support pin 12 cannot at this stage get out of the groove 14 thanks to the above described trip shear. It prevents the profiles 1,2,3,4 to detach one from the other but enables a correct sliding of the plastic profile 3,4 with respect to the metal profile 1,2.

The plastic profile 3,4 shows, on the wall facing the wood fillet 6,7, two wings 15,16. These wings 15,16 have the ends hook-bent so that some channels-that face each other-form between them and the wall of the plastic profile 3,4, from which they originate.

A wing 15 of the plastic profile 3 being a part of the sash prolongs with an arm 17 whose distal end,"U"shaped, hooks to the wood fillet 6. A wing 16 of the plastic profile 4 being part of the jamb prolongs with an arm 18 which embraces the outer radial wall of the wood fillet 7 and houses in an adequate groove 19 created on the wood fillet 7.

The arm 17 of the plastic profile 3 of the sash and the wing 16 of the plastic profile 4 of the jamb are positioned on an edge of the basis on the side of the connection with the wood fillet 6,7. They carry out the double function of fixed constant spacer of the wood fillet 6,7 from the plastic profile 3,4 and of being a container for the percolated bonding resin 5.

The dovetail slots 20,21 are created on the wood fillet wall 6,7 converging towards the outer part of the frame.

On the dead bottom channel existing between the plastic profile 3,4 and the wood fillet 6,7, the resin 5 is injected. The resin also fills the above

mentioned slots 20,21, created on the wood fillet 6,7. The resin 5, once it has set, permanently fixes to the wood fillet 6,7.

The resin 5 also covers the surface of the plastic profile 3,4 converging towards the inner part of the frame but it does not fix to the plastic profile 3,4 itself. The hook-shaped wings 15,16 of the plastic profile, though, give way to crashes that avoid the resin 5 to detach from the plastic profile 3,4 only enabling it to longitudinally slide with respect to it.

The so formed four element profile therefore enables a double longitudinal inner sliding: between the resin 5 and the plastic profile 3,4 and between the latter and the metal profile 1,2.

The metal profile 1 of each sash shows the wall converging towards the inner part of the frame approximately"S"shaped so that, after the coupling of the metal profile 1 with the plastic profile 3, between the two profiles 1,3 a chamber 22 forms, with an extension sufficient to house the screws fixing the accessories of movement of the sash itself.