Patent Description:
As is known in the art, the process in question is a process of hot forming of the sheet constituting the starting material, where, first, the forming device operates to provide a substantial deformation of the sheet in order to obtain a blank of the container, and then gas under pressure is blown into the forming cavity to model the blank so that it will assume the final shape of the container.

The above type of process is widely used in the industrial field for packaging products of various types, being a consolidated and reliable technique.

However, the adoption in a very large number of sectors of containers having increasingly complex shapes has increased considerably the problems to be tackled for implementation of the process referred to. For instance, there are very widespread configurations of containers that have elaborate profiles in various directions, for example along the height of the container and along its circumference.

A problem that arises with complex shapes of the type referred to regards the capacity to guarantee that the sheet will be deformed at the same time preventing any excessive thinning-out in each of the various portions of the container formed, which would render the container subject to lack of structural homogeneity such as to vitiate the mechanical and physical characteristics thereof.

Today, this problem is solved, where possible, using sheet materials having an oversized thickness.

<CIT>, <CIT> and <CIT> disclose certain prior art of possible interest as technical background.

In this context, the object of present invention is to provide a solution that will be improved as compared to the prior art, in particular one that will make it possible to use less material, i.e., a sheet of small thickness, for production of the container.

The above object is achieved using a process having the characteristics recalled in Claim <NUM>.

The annexed claims form an integral part of the technical teaching provided herein.

Further characteristics and advantages of the present invention will emerge clearly from the ensuing description and the annexed drawings, wherein:.

In the ensuing description various specific details are illustrated, aimed at enabling an in-depth understanding of the embodiments. The embodiments may be obtained without one or more of the specific details, or with other methods, components, or materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that various aspects of the embodiment will not be obscured.

The references used herein are provided merely for convenience and hence do not define the sphere of protection or the scope of the embodiments.

As mentioned above, the solution described herein regards a process for obtaining a container of a given shape starting from sheet material. The type of material used may be of a thermoformable or deformable type, for example plastic resins, paper, polymeric material, aluminium, etc., alone or in combination.

In particular, the solution described herein refers to the field of containers made of polymeric material.

With reference to <FIG> and <FIG>, these illustrate an example of application of the solution described herein to obtain a container, designated as a whole by the reference number <NUM>, which has a given height H and extends along the dimension of height, identifying a first portion 100A and a second portion 100B that have a different shape and different dimensions.

In particular, the portion 100A, which is located closer to the mouth <NUM>' of the container, has a roughly cylindrical conformation and extends for a height H1. The portion 100B, which terminates on the bottom of the container, has a smaller cross section with undulated profile and with dimensions that vary along the height H. More in particular, the portion 100B comprises a first stretch 100B' with substantially constant cross section, and a second stretch 100B" with cross section decreasing downwards. As a whole, the portion 100B extends for a height H2.

To obtain a container of this sort starting from sheet material, the process described herein envisages, in general, the steps of:.

The process described herein is characterized in that the step of insertion of the sheet <NUM> into the forming cavity 20A by the forming device <NUM> envisages at least two distinct steps (<FIG>). In the first step, the sheet <NUM> is pushed by a first operating surface S1 of a forming member, which approximates, as regards dimensions, the section of the portion 100A of the container, and is inserted into the forming cavity 20A for a stretch substantially corresponding to the height H1 of the portion 100A (<FIG>). In the second step, the sheet <NUM> is pushed by a second operating surface S2 of a forming member, smaller than the surface S1, which approximates, as regards dimensions, the smaller section of the portion 100B of the container, and is further inserted into the forming cavity 20A for a stretch substantially corresponding to the height H2 of the portion 100B (<FIG>). The surfaces S1 and S2 operate on the sheet coming completely into contact therewith.

As illustrated in <FIG>, at the end of the step of formation of the sheet <NUM> by the forming device <NUM>, the container blank <NUM> obtained has two portions distinct from one another 101A, 101B, which reproduce, in a rough and approximate way, the portions 100A, 100B of the container.

The next step of the process, which envisages blowing gas under pressure into the forming cavity, completes forming of the sheet <NUM> urging it against the entire inner surface of the forming cavity 20A so that it assumes the exact same shape thereof, which corresponds to the shape of the container <NUM> (<FIG>).

In general, it should be noted that the step of preliminary forming of the sheet by the forming device <NUM> may also envisage a number of steps greater than two, on the basis of the shape of the container to be obtained; the step in question may for example envisage three or four steps, and use of a corresponding number of operating surfaces, of dimensions progressively decreasing from one step to the next, as described above.

The present applicant has been able to verify that execution, in the two (or more) distinct steps referred to, of the step of forming of the sheet by the forming device <NUM> makes it possible to improve the degree of homogeneity of the structure of the container <NUM>.

In particular, it may be noted that the differences of thickness in the different points of the container are considerably smaller than those that can be found in containers obtained via conventional forming processes.

Without wishing to provide here any theoretical treatment, the present applicant has in any case reason to believe that the effect found of a greater homogeneity of the structure of the container can be put down to the fact that the division of the process of deformation of the sheet into two (or more) distinct steps, of which the first step is carried out via an operating surface S1 greater than that of the second step (and that of the further steps, if these are envisaged), makes it possible to distribute the sheet material, in terms of thickness, in a more uniform way between the top and bottom portions of the container formed. In this way, formation, in the container, of portions that are considerably thinner and weaker or more brittle than others is prevented.

For the reasons referred to, the process described herein enables use of sheet materials of small thickness as compared to known processes.

On the other hand, the greater degree of homogeneity of the structure of the container obtained evidently constitutes an improvement of the quality of the container itself and moreover affords a prolongation of the shelf life of the end product.

The process described herein hence leads to benefits in terms of saving of material, reduction in the production costs, and reduction of the environmental impact of the containers obtained. Moreover, the process described herein makes it possible to use new materials that cannot be used with conventional processes and to provide shapes that up to now have been difficult to obtain with current systems.

In general, the process described herein can be used for providing containers of any shape so that the shape of the container is not to be understood as in any way limiting the inventive solution disclosed herein. In this connection, it may be noted that the shapes, dimensions, and dimensional ratios of the two surfaces S1 and S2 may be selected according to the specific applications.

The process described herein may envisage preheating of the sheet to be formed or else cold execution of the steps of forming the sheet, this according to the type of material (thermoformable or deformable) constituting the sheet and/or the shape of the container to be obtained.

With reference now to <FIG>, these illustrate in greater detail the forming means of the forming device <NUM> and modes of operation thereof according to a preferred embodiment of the solution described herein. The process may in any case envisage the use of forming means different from the ones illustrated hereinafter.

According to this embodiment, the forming device <NUM> comprises a first forming member <NUM> and a second forming member <NUM>, which are mounted inside one another in a telescopic way and are prearranged for co-operating with the forming cavity 20A of the mould <NUM>. Incidentally, it will be noted that the example illustrated in the figures regards an application in which the mould <NUM> is provided with a plurality of forming cavities 20A and, likewise, the forming device <NUM> is provided with a corresponding number of pairs of forming members <NUM>, <NUM> designed to co-operate with the plurality of cavities 20A.

With reference to the single pair of members <NUM>, <NUM>, they have one and the same main axis of extension that is aligned with the reference axis R of the corresponding forming cavity 20A.

The two members <NUM>, <NUM> are mobile along the reference axis R, both fixedly and according to a relative motion, for carrying out the two distinct steps illustrated above of the step of forming the sheet via the device <NUM>.

In particular, for execution of the first step, the two members <NUM>, <NUM> move into a condition where the ends 41A, 42A thereof are substantially aligned to form as a whole the first operating surface S1 mentioned above (<FIG>).

In the example illustrated, the end 42A of the outer member <NUM> has a substantially conical conformation and, in the condition mentioned, sets itself in a position slightly set back with respect to the end 41A of the forming member <NUM>, so as to constitute an ideal prolongation of the chamfered perimetral edge of the end 41A.

In any case, the above configuration derives from the requirements of the specific application.

The effective area, which is important for the action discussed herein, of the operating surface S1 is represented by its projection in a plane orthogonal to the reference axis R.

In the condition referred to, the two members <NUM>, <NUM> approach the sheet <NUM>, which is gripped between a top surface <NUM> of the mould <NUM> and a bottom surface <NUM> of the forming device <NUM> and push it by way of the operating surface S1 into the forming cavity 20A, for a first stretch of length substantially corresponding to the height H1 (<FIG>).

At the end of the travel of the two members <NUM>, <NUM>, the portion 101A of the container blank <NUM> is thus formed on the sheet <NUM>.

Next, the forming member <NUM> alone performs a further movement along the reference axis R, for a stretch of length substantially corresponding to the height H2 until it reaches the bottom of the forming cavity 20A (<FIG>). During this movement of the member <NUM>, the member <NUM> remains stationary in the position reached at the end of the first step.

Movement of the member <NUM> enables extraction thereof from the outer member <NUM>, and the member <NUM> thus performs, by itself, an action of thrust on the sheet <NUM> through its end 41A, which defines the operating surface S2 referred to above for the second step.

The operating surface S2 evidently has an effective area, with respect to an action of thrust along the reference axis R, that is smaller than that of the surface S1, being defined by just the inner member <NUM>.

The action of the member <NUM> enables formation of the portion 101B of the container blank <NUM> and corresponds to the second step of the forming process.

At the end of this second step, the container blank <NUM> is completed (<FIG>).

At this point, gas under pressure is blown into the forming cavity 20A for completion of the container <NUM> (<FIG>).

Incidentally, it may be noted that, in general, the blowing step can in any case also be started during the first movement of the two forming bodies <NUM>, <NUM> or else during the second movement of just the forming body <NUM>, this according to the specific applications.

This step can be performed according to conventional modalities, so that further details are not provided herein.

The two forming members <NUM>, <NUM> are associated to a driving system that is able to activate the two members simultaneously or separately as illustrated above. In general, the driving system mentioned may comprise two independent driving devices, each for governing one of the two forming members <NUM>, <NUM>.

Such a system can be obtained according to different configurations on the basis of the specific applications.

As anticipated above, the process described herein may envisage forming means different from the ones illustrated above. For instance, instead of providing two forming members coupled together and co-operating in the way illustrated above, it is possible to provide two independent forming members, one of which defines the operating surface S1 and the other the operating surface S2. On the other hand, with reference to the solution illustrated, it should be noted that the mutual arrangement of the two members <NUM> and <NUM> may vary according to the specific applications, in particular according to the particular shapes of the containers to be obtained. For instance, the two members <NUM> and <NUM> could be arranged simply alongside one another and not mounted inside one another. In some embodiments, the forming device <NUM> comprises a thermalconditioning system (heating or cooling means), associated to one or both of the forming members <NUM>, <NUM>, to keep the corresponding ends 41A, 42A at pre-set temperatures. This system may, for example, include an electrical resistance and a thermostat for controlling electrical supply to the resistance.

A preferred application of the process described herein regards production of containers in aseptic environment.

The process described herein has been devised specifically for applications in the field of the foodstuff industry, but the same may advantageously be used also in any other sector, for example in the pharmaceutical field, and in the fields of hygienehealth products, cosmetics, toys, etc..

Claim 1:
A process for obtaining a container (<NUM>) of a given shape from sheet material, comprising the steps of:
- providing a sheet (<NUM>);
- providing a mould (<NUM>) having a forming cavity (20A) , which defines a reference axis (R) and has a shape corresponding to said given shape of said container (<NUM>) ;
- positioning said sheet (<NUM>) over said forming cavity (20A);
- providing a forming device (<NUM>) having forming means (<NUM>, <NUM>) arranged on the side of said sheet opposite to said forming cavity, and operating said forming means for inserting said sheet (<NUM>) into said forming cavity (20A) to deform it until a container blank is obtained (<NUM>) having a shape approximating said given shape; and
- blowing a gas under pressure into said forming cavity (20A) to deform said container blank (<NUM>) until said container (<NUM>) with said given shape is obtained;
wherein said step of inserting said sheet (<NUM>) into said forming cavity includes:
- setting in contact with said sheet a first operating surface (S1) of a forming member (<NUM>, <NUM>) and pushing by means of said first operating surface (S1) said sheet (<NUM>) into said forming cavity (20A), for a first stretch (H1) along said reference axis (R); and
- further pushing said sheet (<NUM>) into said forming cavity (20A) by means of a second operating surface (S2) of a forming member (<NUM>, <NUM>), which is of smaller size than said first surface (S1), for a second stretch (H2) along said reference axis (R),
characterized in that
said forming device (<NUM>) comprises a first forming member (<NUM>) and a second forming member (<NUM>) that can be driven along said reference axis (R) separately or simultaneously,
said process including:
- setting said first and second forming members (<NUM>, <NUM>) substantially in one and the same position along said reference axis (R) so that they define together said first operating surface (S1);
- in this condition, feeding said first and second forming members (<NUM>, <NUM>) in a fixed way with respect to one another along said reference axis (R), for said first stretch (H1); and
- keeping said first forming member (<NUM>) stationary and further feeding said second forming member (<NUM>) along said reference axis (R), for said second stretch (H2), one end (41A) of said second member defining said second operating surface (S2).