BIMETALLIC RADIATORS

DESCRIPTION

The present invention regards the production of modular bimetallic radiators, more in particular it regards a method for producing the aforementioned modular bimetallic radiators and a group of inserts for use in such method. As known, some modular bimetallic radiators are obtained by mutually connecting a plurality of identical modules, each of which consists of a steel tubular insert, intended to receive the heat-carrier fluid, embedded in an external aluminium body representing the radiant element.

According to a known technique, the aforementioned modules are produced by die-casting in a mould, which is provided with an imprint corresponding to each module to be obtained.

The aforementioned technique provides for arranging the steel insert in the mould imprint, in a suitable position, and subsequently filling the imprint with aluminium so as to embed the insert.

The technique described above reveals the drawback of not allowing producing moulds with more than two imprints and, thus, it does not allow obtaining more than two modules per moulding.

The aforementioned drawback arises from the fact that, in case of more than two imprints, the aluminium injection pressure reaches levels that subject the moulds to early wear.

Due to the aforementioned wear, the positioning precision of the inserts in the imprints deteriorates, thus considerably increasing the percentage of discarded material.

The aforementioned high injection pressure reveals the further drawback of potentially deforming the inserts during injection, thus leading to problems similar to those described above.

The present invention has the object of overcoming the aforementioned drawbacks belonging to the known technique described above.

In particular, an object of the present invention is to provide a method for producing modules for bimetallic radiators capable of both allowing to maintain the correct positioning of the steel inserts and preventing the deformation thereof, during the injection of aluminium, in presence of injection pressure higher than the one usually observed in two-imprint moulds. The aforementioned object is attained through a group of inserts for producing modular bimetallic radiators according to claim 1 .

The aforementioned object is also attained through a method for producing modular bimetallic radiators according to claim 8.

Further detailed characteristics of the invention shall be outlined in the relative dependent claims.

Advantageously, the greater stability of the steel inserts during the injection allows using moulds with more than two imprints, thus allowing boosting productivity and hence reducing the unitary costs of the modules.

The object and these and other advantages to be mentioned hereinafter, shall be outlined during the description of a preferred embodiment of the invention, provided by way of non-exemplifying embodiment with reference to the attached drawings, wherein:

- fig. 1 schematically represents the group of inserts of the invention, in axonometric view;

- figs. 2 and 3 schematically represent two different steps of the method of the invention.

The present invention regards the die-casting of bimetallic radiator modules, each module comprising a steel tubular insert embedded in an external aluminium body.

As observable in fig. 1 , each tubular insert 2 is provided with two openings 3 at the respective ends, through which the heat-carrier fluid flows in and out. Preferably but not necessarily, the ends of each tubular insert 2 carry a respective tubular extension 2a, extending according to an orthogonal axis with respect to the main axis of the tubular insert 2, the openings 3 being defined at the ends of the tubular extensions 2a.

In the latter case, the distance between the axes of the two tubular extensions 2a of each tubular insert 2 is referred to as "distance between centres".

In case of tubular inserts 2 without tubular extensions 2a, the term "distance between centres" shall indicate, conventionally, the length of the tubular inserts 2.

The present invention revealed to be particularly adapted to the production of moulds comprising tubular inserts 2 having a distance between centres comprised between 340 mm and 610 mm, in particular equivalent to 350 mm, 500 mm and 600 mm. The method of the invention provides for having a mould for aluminium die-casting, indicated in fig. 2 with reference number 7 comprising a plurality of imprints 8 adjacent to each other and preferably identical, extending according to respective directions parallel to each other.

Each imprint 8 is connected to an injection manifold 11 through a respective supply channel 10.

The method provides for having a plurality of steel tubular inserts 2, preferably identical to each other, in the respective imprints 8, as represented in fig. 3. For this purpose each imprint 8 is provided with corresponding abutment surfaces, not represented in the figure but known per se, adapted to support the respective tubular insert 2 to hold it in position.

After positioning the tubular inserts 2, the mould 7 is closed and aluminium is injected into the injection manifold 11 , which reaches the imprints 8 through the supply ducts 10.

The aforementioned injection allows each tubular insert 2 to be embedded in aluminium thus obtaining a corresponding unfinished bimetallic radiator module.

According to the invention, before arranging the tubular inserts 2 in the mould 7, they are rigidly connected to each other through an aluminium alloy reinforcement framework 4.

For this purpose, the mould 7 is provided with a plurality of connection channels 9 configured to receive the aforementioned reinforcement framework 4.

The reinforcement framework 4 contributes to holding the mutual positions between the different tubular inserts 2 during the injection of aluminium, reducing the displacements and deformations thereof and thus attaining the object of the invention.

Advantageously, the greater stability of the tubular inserts 2 in the mould 7 allows reducing the wear of the latter, increasing the durability thereof, and it allows limiting the deformations of the tubular inserts 2 during injection.

Thus, the aluminium injection pressure can be increased and, in particular, a mould 7 with more than two imprints 8 can be used.

Tests carried out by the party filing the present invention revealed that the reinforcement framework 4 is particularly efficient for simultaneously moulding four modules in a mould with four imprints. More advantageously, the fact that the reinforcement framework 4 is also made of aluminium allows recovering it alongside the riser for subsequent use. Preferably, the connection channels 9 of the mould 7 are configured so that the injected aluminium surrounds the reinforcement framework 4 so as to embed it.

Advantageously, the embedment of the reinforcement framework 4 in the aluminium leads to the casting of the reinforcement framework 4, which merges with the riser into one and facilitates both the removal of the moulded piece and the subsequent reutilisation of the riser.

As mentioned previously, the invention also regards a group of inserts, indicated in its entirety in fig. 1 with reference number 1 , comprising the aforementioned tubular inserts 2 and the relative aluminium alloy reinforcement framework 4.

The tubular inserts 2, preferably identical to each other, are arranged parallel and adjacent to each other.

Preferably, the reinforcement framework 4 is fixed to the tubular inserts 2 by bonding, or through any other known technique capable of allowing bonding steel to aluminium.

As regards the reinforcement framework 4, it preferably comprises two mutually parallel aluminium connection bars 5, which connect each pair of mutually adjacent tubular inserts 2 at the respective ends.

Preferably, each connection bar 5 has a section in square millimetres comprised between 4% and 6% of the distance, in millimetres, between the centres of the two openings 3 of each tubular insert 2.

Advantageously, the tests carried out by the party filing the present invention revealed that the aforementioned diameter is the best compromise between the need of reducing the volume occupied by the reinforcement framework 4 and the need of conferring sufficient robustness to the group of inserts 1 , particularly in presence of four tubular inserts 2.

Preferably, the distance between the aforementioned connection bars 5 is greater than the length of the tubular inserts 2.

In addition, each end of each tubular insert 2 is connected to the corresponding connection bar 5 through an extension 6 coaxial to the tubular insert 2.

Advantageously, the configuration of the reinforcement framework 4 described above allows reducing the deformation that the tubular extensions 2a of the tubular inserts 2 are subjected to due to the pressure induced by the various heat deformations that steel and aluminium are subjected to during moulding. As a matter of fact, by arranging the connection bars 5 at contact with suitable support surfaces of the mould 7, adapted to hold the connection bars 5 in position, the aforementioned extensions 6 serve as tension rods and prevent the aforementioned deformation phenomenon.

Preferably, the distance between the two connection bars 5 is comprised between 1 10% and 120% of the distance between the centres of the two openings 3 of each tubular insert 2 and preferably it is equivalent to 1 16% of the distance between the centres of the two openings 3.

In the light of the above, it is clear that the invention attains the preset object.

As a matter of fact, the mutual connection of the tubular inserts through the reinforcement framework allows limiting the displacements of the inserts and the deformations thereof during injection, thus allowing the use of moulds with more than two imprints.