Technical Field

The present invention relates to a process for the manufacture of composite artifacts.

Background Art

It is well known that, in many industrial sectors, the produced artifacts have to meet very specific and increasingly stringent performance criteria.

Among these, many of them are strongly related to the mechanical properties (e.g., impact strength, flexural strength, wear resistance, tensile strength, resilience, hardness) of the artifacts, which play a major role in cases where the latter carry out structural functions and/or support significant loads during their operational life.

Since mechanical properties are largely given to artifacts by the special materials they are made of, it is easy to appreciate how one of the most critical aspects in the manufacture of artifacts turns out to be precisely the choice of materials to be used.

In this regard, it is exceedingly common in industrial practice to use metallic materials to manufacture artifacts.

The ubiquitous use of such materials is explained by the fact that they give excellent mechanical properties to artifacts and such that their use is suitable for a variety of different technical applications.

It is, however, important to consider that, in the case of the materials involved, meeting the aforementioned performance criteria often comes at the expense of other equally desirable factors, especially the weight of the component itself.

In other words, metallic materials are provided with excellent mechanical properties, but they have, at the same time, high density values, which end up significantly increasing the weight of artifacts manufactured by means of them compared to those manufactured using other types of materials.

This fact gives rise to numerous well-known technical drawbacks, among which one can mention the greater inertia involved, significantly more complex transportation and handling, greater environmental impact, significantly higher thermal-mechanical stresses, and so on.

Keeping all this in mind, it is hardly surprising that the need is, nowadays, increasingly felt to make artifacts having mechanical properties similar to those of the metallic materials and provided, at the same time, with less weight than the latter.

Description of the Invention

The main aim of the present invention is to devise a process for the manufacture of composite artifacts which allows obtaining a composite artifact having mechanical properties similar to those of the metallic materials and weighing less than the latter.

Another object of the present invention is to devise a process for the manufacture of composite artifacts which can overcome the aforementioned drawbacks of the prior art within the framework of a simple, rational, easy and effective to use as well as cost-effective solution.

The aforementioned objects are achieved by this process for the manufacture of composite artifacts having the characteristics of claim 1.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a process for the manufacture of composite artifacts, illustrated by way of an indicative, yet non-limiting example in the accompanying tables of drawings in which:

Figure 1 is an axonometric, overall view of an artifact obtained by means of the process according to the invention;

Figure 2 is a cross-sectional view, along the II-II plane, of Figure 1;

Figure 3 shows, in axonometric view, the implementing phase of the process according to the invention;

Figure 4 shows, in axonometric view, the forming step of the process according to the invention;

Figure 5 shows, in axonometric view, the obtaining step of the process according to the invention; Figure 6 shows, in front view, the coupling step of the process according to the invention.

Embodiments of the Invention

With particular reference to these figures, reference numeral 1 globally denotes a composite artifact obtainable by means of the process for the manufacture of composite artifacts according to the invention.

The process for manufacturing composite artifacts comprises at least the following steps: making A at least one cladding shell 2 by means of at least one additive manufacturing process; providing B at least one filling body 3 which can be inserted to size within the cladding shell 2 and made at least partly of metal foam.

Preferably, making A is carried out by means of one or more additive manufacturing processes of the FDM (fused deposition modeling) type, illustrated purely by way of an example in Figure 3 wherein a machine M is shown suitable for carrying out this technological operation.

Specifically, the cladding shell 2 is made of at least one polymeric material selected from the list comprising: poly etherimide (PEI), polyphenylsulfone (PPSU), polyoxymethylene (POM), thermoplastic polyimide (PEI), polyetherimide (marketed as Ultem), acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polylactic acid (PLA), polyvinyl alcohol (PVA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate glycol-modified (PETG), impact-resistant polystyrene (HIPS), polyamide (PA), polymethylmethacrylate (PMMA), thermoplastic polyurethane (TPU), polybutylene terephthalate (PBT), polypropylene (PP), polyetherimide (PEI), polysulfone (PSU), PEEK, PEEK PVDF, PAEK PPS (or similar amorphous and semi-crystalline high-performance polymers) or any combination of the above.

It is specified, in this regard, that the possibility should not be ruled out of manufacturing the cladding shell 2 by means of materials other than those just listed, such as, e.g., additive materials (glass spheres or fibers, carbon fibers, and so on).

It is also specified that different technological methods cannot be ruled out for manufacturing the cladding shell 2 which methods are suitable for forming the latter starting from the materials contained in the above list.

Specifically, it is possible to manufacture the cladding shell 2 by means of one or more injection molding operations.

Preferably, as shown in Figure 6, the cladding shell 2 is obtained starting from a first half-shell 2a and a second half-shell 2b which can be mutually coupled.

In actual facts, it is possible to make a first half-shell 2a and a second half-shell 2b, e.g. through the above additive manufacturing processes, and couple the latter together to define the cladding shell 2.

Specifically, the two half-shells 2a, 2b are coupleable by interlocking.

In addition, the cladding shell 2 is provided with at least one inner surface 2c, which is adapted to be placed in contact with the filling body 3 as a result of the insertion of the latter into the cladding shell 2, and with at least one outer surface 2d, opposite the inner surface 2c.

It follows that the outer surface 2d and the inner surface 2c are defined by the outer surfaces and by the inner surfaces of the two coupled half-shells 2a, 2b, respectively.

As for the filling body 3, it is preferably made of at least one of: aluminum, magnesium and alloys thereof.

It cannot however be ruled out that the filling body 3 could be made of other metallic materials such as, e.g., tin, brass, gold or others still known to the expert in the field.

In all cases, it is evident how the materials making up the cladding shell 2 and the filling body 3 make it possible to obtain an artifact 1 distinguished by remarkable mechanical properties and, at the same time, a rather low weight.

In fact, the metal foam has very high porosity (usually comprised between 75% and 95% of the total volume) and, therefore, is significantly lighter than solid metal materials, their volume being the same.

At the same time, metal foam offers mechanical properties quite similar to those of more traditional solid metal materials such as, e.g., high tensile and compressive strength, remarkable vibration damping capacity as well as remarkable resilience and hardness.

It follows that the process of the present invention allows obtaining an artifact 1 which is perfectly usable in all those contexts and technical applications where significant mechanical properties are required.

Having clarified this, it is also good to explain that, in accordance with a first possible embodiment shown in Figure 4, providing B comprises at least the following steps: supplying B 1 at least one forming mould 4; inserting B2 within the forming mould 4 at least one metal precursor and at least one foaming agent; forming B3 the filling body 3 in the forming mould 4 from the metal precursor and from the foaming agent.

In particular, the forming mould 4 defines within it at least one forming cavity having size and conformation corresponding to those of the filling body 3 to be formed therein.

At the end of forming B3, the filling body 3 can, therefore, be taken out of the forming mould 4, for example once sufficient time has been waited for it to cool completely.

Alternatively, in accordance with a second possible embodiment shown in Figure 5, providing B comprises at least the following steps: supplying B4 at least one semi-finished element 5 made of metal foam; and obtaining B5 the filling body 3 from the semi-finished element 5 by removal of material, the semi-finished element 5 having a conformation substantially complementary to the cladding shell 2.

In this regard, the removal of material can occur by milling, by turning, by drilling, by any combination of these processes or by other technological operations still known to the technician in the field.

In all cases, obtaining B5 allows the semi-finished element 5 to take on a conformation such that it can be inserted to size in the cladding shell 2. In this regard, subsequently to making A and to providing B, the process comprises at least one phase of joining C the cladding shell 2 to the filling body 3 in order to obtain at least one composite artifact 1.

In detail, joining C comprises at least one step of coupling Cl the cladding shell 2 to the filling body 3 by interlocking.

The process therefore comprises at least one phase of designing and creating D coupling means 6, 7 of the filling body 3 and of the cladding shell 2 having mutual complementarity of shape.

Specifically, the coupling means 6, 7 comprise at least a first coupling element 6, of the male type, made on the cladding shell 2 and at least a second coupling element 7, of the female type, made on the filling body 3.

Having said that, however, the opposite case scenario cannot be ruled out, that is, wherein the first coupling element 6 is made on the filling body 3 and the second coupling element 7 is made on the cladding shell 2.

As visible in Figure 2, the cladding shell 2 has two first coupling elements 6 and, similarly, the filling body 3 has two second coupling elements 7.

It is however easy to appreciate how the number of coupling elements 6, 7 can be completely indicative and can, for that reason, be varied substantially at will. It is understood that the statements set forth in this disclosure with regard to only one of the first coupling elements 6 (e.g., referring to the latter in the singular) are to be regarded as equally valid for the other first coupling elements 6 and that, regardless of their number, the latter are completely identical, functionally and structurally, with each other.

Entirely similar considerations must be taken in account with regard to the second coupling elements 7.

That being said, it is specified that designing and creating D conveniently comprises at least one step of processing DI at least one predefined position of the first coupling element 6 on the cladding shell 2 and at least one corresponding predetermined position of the second coupling element 7 on the filling body 3 such that the coupling elements 6, 7 are allowed to be coupled by interlocking. It follows that if two first coupling elements 6 and two second coupling elements 7 are provided, then two predefined positions and two predetermined positions are processed, that is, one for each coupling element 6, 7.

In other words, the number of predefined positions and of predetermined positions is equal to the number of first coupling elements 6 and of second coupling elements 7, respectively.

The predefined positions and the predetermined positions are, therefore, selected so as to allow the insertion of each first coupling element 6 into a respective second coupling element 7 to allow the coupling of the cladding shell 2 to the filling body 3.

Going into more detail about the coupling means 6, 7 it is important to specify that the first coupling element 6 comprises at least one elastically deformable enlarged portion 6a and by the fact that the second coupling element 7 defines at least one internal seat 7a adapted to contain the enlarged portion 6a to size. As visible from Figure 6, the enlarged portion 6a preferably has a lobed shape.

It is worth noting that the aforementioned expedient allows for an even firmer coupling of the cladding shell 2 and the filling body 3 to each other, counteracting any disconnection of the latter thanks to the interference of the enlarged portion 6a with the seat 7a.

As shown clearly in Figure 6, the first coupling element 6 comprises three mutually connected enlarged portions 6a arranged at substantially equal angular distances from each other.

In other words, the first coupling element 6 has preferably trilobed conformation.

Quite similarly, the second coupling element 7 also defines three seats 7a arranged and conformed in a maimer corresponding to the three enlarged portions 6a.

Again, different conformations of the coupling elements 6, 7 and/or different amounts of enlarged portions 6a and seats 7a, e.g. greater, cannot be ruled out. Conveniently, coupling Cl comprises at least the step of laying C2 at least one adhesive layer on at least one of either the cladding shell 2 or the filling body 3. In this regard, it is good to specify that if laying C2 is carried out on the cladding shell 2, then the adhesive layer can be conveniently applied on the inner surface 2c.

In this way, as a result of the coupling by interlocking between the cladding shell 2 and the filling body 3, the adhesive layer can effectively adhere on both of the latter, adequately fulfilling its function.

Preferably, the adhesive layer is of the type of an epoxy adhesive, or polyurethane adhesive, or other types of adhesive still known to the expert in the field.

In all cases, it is important to note how the step of laying C2 operates in conjunction and synergistically with the step of coupling Cl in joining even more firmly and stably the cladding shell 2 and the filling body 3 to each other. Having described the process covered by the invention, it is also pointed out that the same can be repeated numerous times to obtain a corresponding number of composite artifacts 1.

According to a further aspect, therefore, the present invention also relates to a composite artifact 1 manufactured according to the process outlined so far and having, by virtue of this very fact, density comprised between 0.4 and 0.7 g/cm ³ .

The artifact 1 achieves, therefore, the advantages outlined so far regarding the relevant manufacturing process and is, consequently, perfectly employable in all those operating circumstances where mechanical properties similar to those of metallic materials and/or effective vibration damping are required.

In this regard, taking into consideration the lower density and, therefore, lower weight with volume being equal, it is easy to appreciate how the use of the artifact 1 in the aforementioned operational circumstances is unquestionably more advantageous and preferable than that of solid objects made of metallic materials.

Having explained this, it is specified that in accordance with what was previously anticipated regarding the process: the first coupling element 6 is provided with at least one elastically deformable enlarged portion 6a; and the second coupling element 7 is provided with at least one internal seat 7a adapted to contain the enlarged portion 6a to size.

Therefore, as already explained, the interlocking between the coupling elements 6, 7 occurs as a result of the interference, after their mutual coupling, between the elastically deformable enlarged portion 6a and the respective seat 7a.

It is easy to appreciate how this type of coupling is particularly stable, thus ensuring a firm union between the cladding shell 2 and the filling body 3.

It has in practice been ascertained that the described invention achieves the intended obj ects .

In particular, the fact is emphasized that manufacturing a composite artifact comprising a cladding shell and a mutually coupled metal foam filling body gives the artifact similar mechanical and vibration-damping properties to those of the metallic materials, while at the same time reducing its weight compared to the latter.