EP0543695B1 - Method and installation for forming the body of a metallic can - Google Patents

Description

The invention relates to a box body shaping installation according to the preamble of claim 1.

There is known a box body shaping process generally implemented on box bodies formed by the assembly of at least two elements, typically a tubular part and a bottom crimped at one end thereof. The tubular part can be a cylinder with circular, rectangular or square section. This method uses a core mechanism intended to be introduced axially inside the box body, through the opening of the latter and having sectors which can be spaced apart from each other radially outwards. so as to come into contact with the internal wall of the box body to be conformed. This operation prints a permanent deformation to the box body and the shape obtained depends on that of the core sectors. In such a system, the deformation means and its actuation system are essentially mechanical. The boxes thus shaped have appearance defects inherent in the shaping system itself. In particular, the imprints of the various sectors are relatively visible on the walls of the box body. The latter cannot therefore have a perfectly regular surface condition. Fingerprints can even result in scratches on the varnish that can initiate corrosion. They can also constitute initiations of rupture. In addition, the mechanism is complicated and expensive.

The document GB-A-982 808 describes a machine for shaping a container by hydroforming but the very structure of the machine does not make it possible to obtain the high production rates which are essential in the field of the manufacture of box bodies. metal packaging.

Document US-A-2972971, on which the preamble of claim 1 is based, also describes a hydroforming machine with automatic feeding means hollow bodies. The hydroforming station is separated from the conveyor and the transfer of the hollow bodies is effected by a reciprocating mechanism which limits the production rate.

The invention provides a more efficient arrangement making it possible to obtain hydroformed can bodies with an excellent surface finish while achieving high production rates.

According to the invention, this object is achieved by an installation for shaping metal box bodies comprising a conveyor, a filling station with at least one box body, provided with means for introducing a desired quantity of a liquid into it. ci and a shaping station arranged downstream of said filling station, comprising at least one matrix adapted to receive such a can body and internally shaped according to the desired final shape of said can body, characterized in that said conveyor extends less between a point upstream of the filling station and a point downstream of the shaping station, and comprises bases which are integral with the conveyor and movable with it, each having a shape adapted to receive a box body and in that the or each matrix comprises two lateral half-shells mounted movable so as to be able to be separated from one another and provided with recesses defined in the vicinity of their ends in lower, in that said recesses are shaped so that said half-shells can adapt to the aforementioned base by surrounding it so that in the configuration where the two half-shells are applied one against the other, said base constitutes the bottom of the matrix, and in that a connection end piece adaptable in a sealed manner to the opening of said box body and connected to a source of pressurized fluid comes to adapt to the end of an opening upper of said matrix.

On leaving the die, the shaped can body is generally emptied of the liquid it contains and fed to an oven or similar drying means. The liquid can simply be water. We can however take advantage this phase of conformation to apply an internal protective coating on the walls of the box body. To do this, it suffices that the liquid is added with a protective agent capable of leaving on said walls a protective film after emptying and drying of the can body.

According to another advantageous characteristic of the invention, an axial force can be applied to the body of the box while the pressure is applied in said residual volume, to promote the "movement" of the metal which will be applied against the internal walls of the matrix. This avoids excessively thinning the metal in certain critical deformation zones. To do this, the aforementioned connection end piece may advantageously include an axially shaped sliding plug to adapt in leaktight manner to the opening of the box body trapped in the matrix. The plug is stressed during the phase of shaping the can body to apply the axial force mentioned above to the latter.

• la figure 1 est une vue générale schématique de l'installation;
• la figure 2 est une vue schématique de détail suivant la coupe II-II de la figure 1;
• la figure 3 est une vue de dessus de la figure 2;
• la figure 4 est une vue schématique du dispositif d'orientation du corps de boîte;
• la figure 5 est une vue schématique des différentes parties d'une matrice sur le point de se refermer sur un corps de boîte;
• la figure 6 est une vue analogue à la figure 5 illustrant la matrice renfermant un corps de boîte sur le point d'être conformé; et
• la figure 7 est une vue analogue à la figure 6 montrant les mêmes éléments après conformation dudit corps de boîte.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an installation in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings. wherein:

• Figure 1 is a general schematic view of the installation;
• Figure 2 is a schematic detail view along section II-II of Figure 1;
• Figure 3 is a top view of Figure 2;
• Figure 4 is a schematic view of the orientation device of the box body;
• Figure 5 is a schematic view of the different parts of a matrix about to close on a box body;
• Figure 6 is a view similar to Figure 5 illustrating the matrix containing a box body about to be shaped; and
• Figure 7 is a view similar to Figure 6 showing the same elements after shaping of said box body.

The installation shown in the drawings successively comprises a supply conveyor 11 on which the box bodies to be conformed are deposited, a main conveyor 12, along which the main treatment stations are arranged, a transfer conveyor 13 and an oven 14. The transfer conveyor 13 is installed between the outlet of the main conveyor 12 and the outlet of the oven 14. A feed turret 16 actuated sequentially is installed between the feed conveyor and the main conveyor. A similar evacuation turret 18 is installed between the main conveyor and the transfer conveyor. All the elements described so far are of a known type. However, the main conveyor is equipped with bases 20 each having a shape adapted to receive a box body. The drive means of the feed turret and of the main conveyor are synchronized in such a way that each box body 21 taken by said feed turret is deposited on a base. To facilitate this transfer, the bases 20 are made of magnetic material, which facilitates the installation of the box body of sheet steel.

As can be seen in FIG. 2, synchronization is ensured by the fact that the feed turret 16 and the main conveyor 12 are driven by the same motor 22 via a gearbox 24 comprising two perpendicular output shafts, a shaft 25 for driving the turret and a shaft 26 for driving a drive wheel 27 of said main conveyor.

The box bodies 21 shown in the example described are more particularly intended to contain products intended to be sprayed in the form of an aerosol. Such a box body conventionally consists of a cylindrical shell with circular section 26 of a bottom 27 crimped to this ferrule and a marquee 28 set at the top of the ferrule and adapted to receive a spraying device. To personalize the packaging, it is desired to conform such a box body in a particular way and in particular to modify the shape of the shell. Of course, this is only an example of application of the principle of the invention, which can be adapted to give any desired shape to any type of box body.

Along the main conveyor, are successively arranged a filling station 30 with at least one box body and a shaping station 32, downstream of said filling station and comprising at least one matrix 34 (FIG. 5) adapted to receive a like box body. In the example shown, the filling station comprises a ramp 36 connected to a source of liquid 38 and making it possible to feed four box bodies simultaneously, while the shaping station is equipped with four dies 34. The filling station is provided with means for introducing a desired quantity of liquid, for example water, into each of the box bodies. Each matrix 34 is internally shaped according to the final shape which it is desired to give to the box body. Each matrix is completed by a connection end piece 40 which can be adapted in leaktight manner to the opening of the corresponding box body and this end piece is connected to a source of pressurized fluid 42 which may be a liquid or even air.

In the example shown, the four connection end pieces 40 are integral with the same unit 41 which can move vertically and are connected to the source of pressurized fluid 42. The liquid 43 introduced into the box bodies at the filling station 30 is the more often water but possibly this liquid can be added with a protective agent capable of forming a coating on the internal walls of the box body, after emptying and drying thereof. The quantity of liquid 43 admitted into each can body at the filling station is determined according to the type of can body treated so that only a relatively small residual volume 44 remains in the vicinity of the upper opening of the box body. In addition, each base 20 is pivotally mounted about a main axis of symmetry corresponding to that of the box body which comes to take place on said base. The installation is completed by a box body orientation station 46, combined here with the filling station, that is to say arranged upstream of the shaping station. This orientation station includes means for rotating the base so as to bring the box body to a predetermined position. This is illustrated in FIG. 4. It can be seen that each base 20 is mounted rotating by means of a ball bearing 47 and, during filling, it is coupled to a stepping motor 48 controlled by an electronic unit 49 itself. even controlled by a sensor 50 arranged opposite the box body. This sensor is sensitive to a particularity of the box body, a longitudinal weld 51 in the present case. The electronic unit controls the motor 48 until said weld is in a well-defined position defined by the location of the sensor 50. This prior orientation of the box body has several advantages. In all circumstances, it makes it possible to position the weld and therefore, if it has a significant excess thickness, to make it coincide with a corresponding longitudinal groove in the matrix. Furthermore, if the conformation that it is desired to give to the box body is not symmetrical with respect to its main axis, this prior orientation makes it possible to position the screen-printed decoration on the surface of the box body with such or such given relief by conformation. The means for orienting the box bodies could be different and consist, for example, of a mechanism adapted to redirect each box body mounted on a non-pivoting base.

As shown in Figures 5 to 7, each matrix comprises two lateral half-shells 55 a , 55 b , actuated by jacks not shown, oriented horizontally. The two half-shells are therefore mounted movable so that they can be separated from one another. They are provided, at their lower ends, with semi-circular recesses 56. More specifically, these recesses are shaped so that said shells can adapt to a base mentioned above by surrounding it. In the configuration where the two half-shells are applied one against the other by enclosing a box body (FIG. 6), the base 20 of the main conveyor therefore constitutes the bottom of the matrix. Each connection end piece 40 fits at the end of an upper opening of the matrix so that pressurized fluid can be injected into the residual space left above the liquid filling the box body, thereby causing the deformation of said box body until it comes to marry the internal wall of the matrix 34, reproducing the desired conformation. Holes 58 forming vents are made in the wall of one of the half-shells to allow the evacuation of the air trapped between the matrix and the box body, during this shaping phase.

In addition, each connection end piece 40 comprises a plug 60 sliding axially and provided with an application face 62 shaped to adapt in leaktight manner to the opening of the box body trapped in the matrix. In the example shown, this application face has a shape substantially reproducing the impression of the marquee, so that said sliding plug 60 is applied over substantially the entire surface of the marquee of the box body. The plug is drilled to allow the introduction of pressurized fluid. Furthermore, the connection endpiece comprises means for forcibly applying this plug to the opening of the box body. More specifically, the connection end piece comprises a pressure chamber 64, a movable wall of which is at least partly formed by the upper end of the sliding plug, opposite to said application face of the latter. This pressure chamber communicates with a source of pressurized fluid which is here the source of pressurized fluid 42 intended to cause the conformation of the can body. To this end, the pressure chamber 64 is coaxial with and communicates with the pressurized fluid inlet pipe 65. A flexible waterproof membrane 66, here made of elastomeric material, is interposed in said pressure chamber to separate the sliding plug 60 from the fluid admitted into this chamber. In this way, when the pressure is admitted into said residual space of the box body, this results at the same time a force exerted on the sliding plug 60 and therefore on the box body along its longitudinal axis. This action pushes the metal from the upper part of the shell 26 as it deforms radially outward to match the internal walls of the matrix. Therefore, it avoids thinning and weakening locally the wall of the shell, at the places where the deformation thereof is most accentuated. At the end of this operation, the situation is that which is illustrated in FIG. 7. The movable elements of the matrix are again displaced to release the four shaped box bodies, which are then conveyed on the transfer conveyor, by the action of the evacuation turret 18. Along this conveyor, and upstream of the drying oven, the shaped box bodies pass through an emptying station 68, known per se, which manipulates the box bodies to pour the liquid they contain. This liquid is recovered in a tank 69 and possibly recycled to the filling means (more precisely to the reservoir 38), in particular if it contains a protective agent. Finally, when the box bodies are empty, they pass through the drying oven 14 before being conveyed to other treatment stations.

Claims (9)

1. Installation for forming metal can bodies (21) comprising a conveyor (12), a station (30) for filling at least one can body (21), provided with means (36, 38) for introducing a desired quantity of liquid (43) therein and a forming station (32) arranged downstream of the said filling station (30), having at least one die (34) adapted to receive such a can body (21) and shaped internally according to the final desired shape of the said can body (21), characterised in that the said conveyor (12) extends at least between a point upstream of the filling station (30) and a point downstream of the forming station (32), and comprises pedestals (20) fixed to the conveyor (12) and movable therewith, each having a shape adapted to receive a can body (21), and in that the die or dies (34) have two lateral half-shells (55a, 55b) movably mounted so as to be able to be separated from each other and provided with hollows (56) defined in the vicinity of their bottom ends, in that the said hollows (56) are shaped so that the said half-shells (55a, 55b) can adapt to an aforementioned pedestal (20) whilst surrounding it so that, in the configuration in which the two half-shells (55a, 55b) are applied against each other, the said pedestal (20) constitutes the base of the die (34), and in that a connecting piece (40) which can be sealingly fitted to the opening of the said can body (21) and connected to a pressurised fluid source (42) is fitted to the end of a top opening of the said die (34).
2. Installation according to Claim 1, characterised in that it comprises means for reorienting the can bodies (21).
3. Installation according to Claim 1 or 2, characterised in that the said pedestals (20) are made from a magnetic material.
4. Installation according to one of the preceding claims, characterised in that each pedestal (20) is mounted so as to pivot about a principal axis of symmetry corresponding to that of the can body and in that it also has a station (46) for orienting the said can body (21) disposed upstream of the said forming station (32) and comprising means (47-50) for rotating the said pedestal (20) so as to bring the said can body (21) into a predetermined position.
5. Installation according to one of the preceding claims, characterised in that the said connecting piece has an axially sliding plug (60), provided with an application face (62) shaped so as to adapt sealingly to the opening of a can body (21) trapped in the said die (24), the said sliding plug (60) having a drilling to allow the introduction of the pressurised fluid and in that it also has means (64, 66) for forcibly applying the said plug to the opening of the said can body.
6. Installation according to Claim 5, characterised in that the said connecting piece (40) has a pressure chamber (64), a movable wall of which is at least partly formed by one end of the said sliding plug (60), opposite to the said application face (62) thereof.
7. Installation according to Claim 6, characterised in that the said pressure chamber (64) communicates with the aforementioned pressurised fluid source (42).
8. Installation according to Claim 7, characterised in that a flexible impervious membrane (66), for example made from elastomer, is interposed in the said pressure chamber (64) in order to separate the said sliding plug (60) from the fluid admitted into this chamber (64).
9. Installation according to one of the preceding claims, characterised in that the aforementioned liquid (43) includes a protective agent able to form a coating on the internal walls of the said can body (21).

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