WO2018203110A1

WO2018203110A1 - Method for forming objects made of metal by backward extrusion and die for carrying out the method

Info

Publication number: WO2018203110A1
Application number: PCT/IB2017/052610
Authority: WO
Inventors: Felice COLETTA
Original assignee: I.N.C.A. S.P.A. A Socio Unico
Priority date: 2017-05-04
Filing date: 2017-05-04
Publication date: 2018-11-08

Abstract

The present invention relates to a method for forming objects made of metal or metal alloys. A slug (1) of metal or metal alloy is placed in a forming chamber (22) of a die (2). The slug is pressed (402) by inserting a punch (3) through the single opening (202) of the forming chamber (22) till the material of the slug (1) flows out from the die. The die (2) is assembled by joining (401) at least a first (20) and a second part (21), which comprise each one inner walls defining the forming chamber (22). The forming chamber (22) has, at least in a plane parallel to the opening (202), an area larger than the port of said opening (202). After pressing the slug (1), the first (20) and second (21) parts are separated and the formed object is removed (405).

Description

METHOD FOR FORMING OBJECTS MADE OF METAL BY BACKWARD EXTRUSION AND DIE FOR CARRYING OUT THE METHOD

TECHNICAL FIELD

The present invention relates to a method for forming metals and metal alloys. The invention is preferably and advantageously applied to the production of caps and other elements intended for packaging of cosmetic products.

STATE OF THE ART

Many methods for working metals and metal alloys are currently known.

A first known type of metalworking is rolling process, that is the production of thin metal sheets having the desired thickness that then can be bent, cut and processed.

In order to obtain solid shapes by means of a single operation, impact extrusion technique is known, shown in figure 1, which provides a slug 1 of metal material, typically aluminium or an alloy thereof, to be placed into a die 2 firmly attached to the base of a press provided with a related punch 3. Then, (FIG.l on the right), the punch 3 is inserted into the die to press the slug 1, which gets deformed and it goes upwards following the profile of the punch 3.

The limit of such working technique substantially is due to the shapes that can be obtained, typically cylinders or parallelepipeds with smooth faces. Therefore generally in order to obtain metal objects having a complex shape, such as caps or shapes curved and/ or with reliefs, it is necessary to provide other techniques after rolling, drawing or extrusion, such as expansion with special rubbers. However even such operations have some drawbacks, for example the process of expansion with special rubbers allows metal sheets with a reduced thickness to be deformed and it stresses a lot the metal that may get broken. The shapes obtained in this manner by expansion with special rubbers moreover are very light and in few cases, such as in the production of caps for cosmetics, it is necessary to ballast the shapes by means of additional operations.

Therefore there is the need of finding metalworking methods allowing complex shapes to be obtained in a quick and effective manner, reducing production costs and time. OBJECTS AND SUMMARY OF THE INVENTION

Therefore the object of the present invention is to solve one or more of the drawbacks of metalworking techniques described above.

Particularly it is the object of the present invention to reduce working time necessary to form objects made of metal, or metal alloy, curved and/ or provided with reliefs.

These and further objects of the present invention will be more clear from the following description and from the annexed claims, which are an integral part of the present description. According to a first aspect, the invention therefore relates to a method for forming metals and/ or metal alloys comprising the steps of:

- placing a slug of metal material or metal alloy into a forming chamber of a die, the forming chamber being provided with a single opening;

- pressing the slug by inserting a punch through the opening of the forming chamber till the slug material flows out from the die; and wherein

- before pressing the slug, the die is assembled by joining at least a first and a second part, said first and second part comprising each one inner walls defining the forming chamber, the forming chamber having, at least in a plane parallel to the opening, a shape with an area larger than the port of said opening,

- after pressing the slug, said first and second parts are separated and the formed object is removed.

Thus such process, with a single working, allows objects to be obtained with such shapes that otherwise could not be obtained by a conventional impact extrusion process or other conventional working methods. Thus considerable saving is obtained as regards production costs and time.

In one embodiment, the forming chamber comprises, near the opening of the chamber, smooth walls developing on planes parallel to a central axis of the opening. The same chamber then comprises, in a position distal from the opening, walls with portions approaching and/ or moving away from said central axis. Such portions thus cold-forming particular shapes, such as curved surfaces or reliefs, of the object, that otherwise could not be obtained in a conventional single process. The present invention relates also to a die and to a relevant forming assembly allowing the above mentioned methods to be implemented and that are better described in the detailed description below.

Further characteristics and advantages of the present invention will be more clear from the following detailed description of some preferred embodiments thereof, with reference to the annexed drawings.

The different characteristics in the individual arrangements can be combined with one another as desired if advantages resulting specifically from a particular combination should be used.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described here below with reference to some examples provided by way of example and not as a limitation, and shown in the annexed drawings. These drawings show different aspects and embodiments of the present invention and, where appropriate, reference numerals showing like structures, components, materials and/ or elements in different figures are denoted by like reference numerals.

Figure 1 is two steps of impact extrusion technique;

Figure 2 is a section view of a cold-forming assembly according to the present invention;

Figure 3 is the assembly of figure 2 in a different step working an object made of metal or metal alloy;

Figure 4 is a flow chart of a method for forming objects made of metal or metal alloys;

Figures 5A and 5B are a section view and an exploded view of a detail of a die alternative to that of figure 2 and 3 respectively. Figures 6 A and 6B are a further die alternative to that of figures 2 and 3, before and after being assembled.

DETAILED DESCRIPTION OF THE INVENTION

In the description below, in order to disclose the figures, identical numerals or reference symbols are used to denote constructional elements having the same function. Moreover, for clarity purposes, some references can be not repeated in all the figures.

While the invention is susceptible of various modifications and alternative constructions, some preferred embodiments are shown in the drawings and will be described in details herein below. It should be understood, however, that there is no intention to limit the invention to the specific disclosed embodiment but, on the contrary, the invention intends to cover all the modifications, alternative constructions and equivalents that fall within the scope of the invention as defined in the claims.

The use of "for example", "etc.", "or" denotes non-exclusive alternatives without limitation, unless otherwise noted. The use of "includes" means "includes, but not limited to", unless otherwise noted.

With reference to figures 2 and 3 they show a forming assembly 100 for implementing a method for forming metals and metal alloys according to the present invention. The examples are about forming a cap, but it is clear that are not limited to forming such object.

The forming assembly 100 comprises a punch 3 and a die 2 composed of two parts, denoted by reference numerals 20 and 21, that can be moved near and away from each other. The forming assembly 100 further comprises means for moving the punch that are not shown and not further described since known. In the preferred embodiment the punch 3 is part of a mechanical press and the lower part 21 is intended to be attached to the press and therefore it remains still during metalworking, while the upper part 20 rests on the lower part 21 to form a forming chamber 22 intended to be filled with the metal.

The lower part 21 of the die 2 has an upper opening 220 intended to receive a slug 1 of metal or metal alloy. The shape of the opening 220 depends on the shape of the object desired to be made by the forming process. In the example of figure 2 the opening 220 has a flat horizontal base 221 and side corrugated walls 222 extending from the flat base 221. Obviously other embodiments are possible.

The upper part 20 of the die 2 on the contrary has a through hole 200 developing along direction x of the running direction of the punch 3. The through hole 200 has a shape, in plan view, preferably equal to punch shape, but with slightly higher dimensions to allow the metal to be extruded as described below. In case of a square punch, therefore, the through hole 200 is preferably selected with a square shape. The through hole 200 has, inside, preferably smooth surfaces 201 distant from the punch preferably from 40 to 80 millimeters.

According to the invention, in a preferred embodiment suitable to form a cap, the opening 220 has an inlet port 223 with a size greater than the port 202 of the through hole 200 composing the single opening of the forming chamber 22.

Therefore the part 20 has such an arrangement that, when placed above the part

21, it partially covers the port 223. Thus the forming chamber 22 has a larger lower volume, intended to form the cap head, and a thinner upper volume intended to form the cap neck. The forming chamber 22 therefore has in at least one plane parallel to the opening 202, a shape with an area higher than the port of the opening 202.

In operation, the slug of metal (or alloy thereof) is placed (step 400 of fig.4) inside the opening 22 of the lower part of the die 2. Then (step 401) the die is closed by clamping the upper part 20 on the lower part 21, such to obtain the desired forming chamber 22.

Now the punch (step 402) is lowered into the hole 200 to cold press the slug. In case of aluminium it is possible to use a press with a capacity in the order of 50 tons, exerting a pressure within the range 20000KG/cm² or 2000MPa with 60T press.

The metal, pressed by the punch 3, expands into the forming chamber 22 taking all the space till flowing out from the hole 200 following the walls of the punch 3, such as shown in figure 3.

When the punch reaches the maximum travel position provided by the working, it is removed (403) and the die 2 is opened (404) by lifting the upper part 20 and possibly by opening the side walls (called also as split walls) of the die 2.

Now the formed object can be removed (405). From the description above the characteristics of the forming assembly and of the related method for forming metals and metal alloys of the present invention are clear, as well as relevant advantages are clear.

It is also clear for the person skilled in the art that many variants are possible without for this reason departing from the scope of protection of the patent as it results from the annexed figures.

For instance the die 2 can be composed of more than two parts. For example, such as shown in figure 5A and 5B, it is possible to provide a modular die where the lower part 21 is composed of a first body 210 acting as a substantially rectangular base, on which the slug will be placed, and of movable side walls 211 and 212 attached to the base. In the example of figure 5A and 5B the body 210 is a circular- base cylinder, while the two side walls 211 and 212 are two prisms with semicircular base that are clamped about the body 210.

In another embodiment, the upper part 20 of the die can be shaped such to comprise all the walls composing the forming chamber except for the base one, such as shown in figures 6A and 6B. In this embodiment, the die 2 comprises a base body 610 that is the lower part of the die 2 and an upper body 600 comprising a forming cavity 630 that axially passes through the upper body 600.

The base body 610 has such a size to close the lower opening of the forming cavity 630. The latter has, inside, walls at least partially machined (e.g. corrugated) in a region proximal to the base body 610, while, at the opposite end, that is in the region intended to receive the punch, it has smooth walls.

It is also clear that the several steps of the method described above with reference to figure 4 can be performed in a different order or can be grouped together. For example a part of the die, for instance the part 20 of figure 2 and 3, can be attached to the punch 3, therefore the step closing (401) and opening (404) the die can be performed contemporaneously with the step pressing the slug (402) and step removing the punch (405) respectively.

Then generally the forming chamber can have different shapes depending on the desired object. Preferably, however, where the forming chamber comprises:

- in proximity of the opening of the chamber (numeral 202 in fig.2) smooth walls developing on planes parallel to a central axis (x) of said opening (202). That is to say, preferably the opening 202 will be the port of a cylindrical or parallelepiped hole; in a position distal from the opening of the forming chamber, walls with (curved or straight) portions moving near and/ or away from said central axis (x). Such portions for example will be a shaped profile of the head of a cap, or reliefs that will have to be present on the object.

Claims

1. Method for forming objects made of metal or metal alloys, comprising the steps of:

- placing (400) a slug of metal material or metal alloy into a forming chamber (22) of a die (2), the forming chamber (22) being provided with a single opening (202);

- pressing (402) the slug by inserting a punch (3) through the opening (202) of the forming chamber (22) till the material of the slug (1) flows out from the die; characterized in that

- before pressing the slug (1), the die (2) is assembled by joining (401) at least a first (20) and a second part (21), said first (20) and second (21) part comprising each one inner walls defining the forming chamber, (22) the forming chamber (22) having, at least in a plane parallel to the opening (202) , a shape with an area larger than the port of said opening (202),

- after pressing the slug (1), said first (20) and second (21) parts are separated (404) and the formed object is removed (405).

2. Method according to claim 1, wherein the forming chamber (22) comprises:

- in proximity of said opening (202) smooth walls developing on planes parallel to a central axis (x) of said opening (202), and

- in a position distal from said opening (202) walls with portions moving near and/ or away from said central axis (x).

3. Method according to claim 2, wherein said portions that move away and/ or near said central axis (x) form reliefs in a surface of the formed object.

4. Method according to any of the preceding claims, wherein the punch (3) is run along said central axis (x) of said opening, and wherein the distance between one surface of the punch and an edge of said opening facing the punch ranges from 40 to 80 millimeters.

5. Method according to claim 1, wherein at least one of said first (20) and said second (21) part is moved with the punch (3).

6. Die (2) for forming objects made of metal or metal alloys, comprising a forming chamber (22) provided with a single opening (202), characterized in that it comprises at least a first (20) and a second (21) separable parts, that, when joined, define said forming chamber (22) and in that the forming chamber (22) has, at least in a plane parallel to the opening (202) a shape with an area greater than the port of said opening (202).

7. Die according to claim 6, wherein the forming chamber (22) comprises: - in proximity of said opening (202) smooth walls developing on planes parallel to a central axis (x) of said opening (202), and

8. Die according to claim 7, wherein said portions moving away and/ or near said central axis (x) form reliefs in a surface of the formed object.

9. Forming assembly comprising a die according to any of the claims 6 to 8, a punch (3) and means intended to move said punch (3) into e out from the forming chamber of said die.

10. Forming assembly according to claim 9, wherein the punch and means intended to move the punch (3) are part of a press.