The present invention relates to a system for blow molding plastic containers.

Systems for blow molding plastic containers are known which comprise an apparatus for blow molding preforms, so as to obtain containers such as for example bottles; typically, known apparatuses comprise one or more units for forming at least one container.

The preforms are fed to the apparatus for blow molding the preforms by means of a conveyor that is associated with an oven for thermal conditioning of the preforms.

The conveyor is normally associated with a preform transfer device, which is constituted for example by a handling device, which picks up the preforms from the conveyor to transfer them to the blow molding apparatuses.

For very limited hourly production rates, which are typical for example of system designed for the blow molding of preforms to obtain medium/large size containers, so-called linear apparatuses are used in which the forming units are supported by a base frame and are provided with means for relative linear movement between two mold parts adapted to move between the loading/unloading position, in which the first mold part is spaced from the second mold part in order to allow to feed the preform and unload the blow molded container, and an active blow molding position, in which the first mold part is close to the second mold part in order to form at least one forming cavity for a respective container.

The linear movement, combined with the fact that these forming units have a closed frame, allows an extremely simple management and a high stiffness of the press constituted by the two mold parts during the blow molding operations, in addition to having a relatively low production cost.

For systems designed instead for high hourly production rates, used for example to produce small or medium-sized containers, so-called "rotary" apparatuses are used to form the containers and are constituted by a blow molding carousel that can rotate about a main rotation axis and is provided, at its own peripheral region, with a plurality of forming units.

Each forming unit comprises two mold parts which can move, with respect to each other, about a pivoting axis.

In some cases, each forming unit forms two forming cavities which are mutually spaced along a direction that is tangent to the peripheral region of the carousel.

Currently known linear systems, if used for the manufacture of medium- or large-sized containers, have some drawbacks.

In fact, if it is necessary to increase the production rate, one possibility is to increase the number of cavities of the individual forming unit.

By doing so, the number of preforms that must be accumulated on arrival from the oven and transferred to the forming unit increases.

Moreover, if a multiple- cavity linear forming unit is used, the preforms that arrive progressively from the heating oven have to wait for different times from exit from the oven to the moment of forming and this entails a lack of uniformity of the temperature that can cause inconstant characteristics in the containers obtained during the same forming process.

Carousel systems instead have considerable costs, if hourly production rates that are not particularly high are required, and have, with reference to the blow molding of preforms to obtain medium- or large-sized containers, a certain complexity in the provision of the devices for transferring the preforms and the formed containers, and in particular of the clamp-like handling device, which, especially if forming units that form two forming cavities are used, must transfer the preforms with a movement that is tangential with respect to the carousel.

The aim of the present invention is to solve the problems and obviate the drawbacks described above, by providing a system for blow molding containers that is extremely easy and practical to use.

Within this aim, an object of the invention is to provide a system for blow molding containers that is extremely simple from the constructive standpoint and is capable of allowing an optimum management of the process.

This aim, as well as this and other objects which will become better apparent hereinafter, are achieved by a system for blow molding containers according to the provisions of claim 1.

Further characteristics and advantages of the invention will become better apparent from the description of some preferred but not exclusive embodiments of a system for blow molding containers according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a schematic perspective view of a system according to the invention during the step of insertion of the preforms in the forming unit after they have been taken from the feeder line in output from the heating and thermal conditioning oven;

Figure 2 is a view, similar to Figure 1, of a constructive variation during the step of feeding the preforms to be blow molded to the blow molding apparatus;

Figure 3 is a view of the step of picking up the preforms from the feeder line.

In the exemplary embodiments that follow, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments.

With reference to the cited figures, the present invention relates to a system, generally designated by the reference numeral 1 , for blow molding plastic containers.

The system 1 comprises a line 20 for feeding preforms 21 to an apparatus 2 for blow molding the preforms 21. According to the present invention, the apparatus 2 for blow molding containers comprises a carousel 3 that can rotate about a main rotation axis, designated by the reference numeral 100, and supports a plurality of units 4 for forming at least one container.

In particular, each forming unit 4 comprises a first mold part 5 and a second mold part 6 that can translate with respect to each other along a movement direction 101 in order to pass from a loading/unloading position, in which the first mold part 5 is spaced from the second mold part 6, and an active blow molding position, in which the first mold part 5 is close to the second mold part 6 in order to form at least one forming cavity 11 for a respective container.

In particular, the rotating carousel 3 can rotate with a continuous rotary motion about the main rotation axis 100.

In this manner, high productivity is achieved, reducing idle times. Preferably, the movement direction 101 has exclusively a linear or rectilinear component.

In order to provide the movement of at least one of the first and second mold parts 5, 6 along the movement direction 101 it is possible to use conveniently a toggle device.

Advantageously, each forming unit 4 comprises a supporting frame that has a closed structure 30 adapted to give high rigidity.

In particular, the supporting frame with closed structure 30 comprises two lateral posts 31 that rise from a footing 33 and are connected in an upper region by a crossmember 32.

Each forming unit 4 forms at least one forming cavity 11 for blow molding respective containers; in some cases the forming unit can have two or more forming cavities 11 for blow molding respective containers.

In particular, if the forming unit 4 forms at least two forming cavities 11, they are extended along respective longitudinal axes 102a, 102b that are substantially parallel. Preferably, the longitudinal axes 102a, 102b of the forming cavities 11 are extended substantially parallel to the main rotation axis 100 of the carousel 3.

Advantageously, the feeder line 20 comprises at least one conveyor 22 for preforms 21 and at least one pickup element 23.

The pick-up element 23 is adapted to pick up the preforms 21 from the conveyor 22 to feed them to the forming units 4.

As shown in Figure 2, it is possible to provide the feeder line with two or more pick-up elements 23.

The apparatus 2 is of course associated with a line, for example of the known type, for discharging the blow molded containers 12.

The discharge line can comprise one or more discharge elements that have a structure and a kinematic movement mechanism that are similar to those of the pick-up elements 23.

According to a particularly important aspect of the present invention, the forming units 4 are arranged, with their respective movement directions 101, along a broken line that is extended around the main rotation axis 100 of the carousel 3.

According to a preferred embodiment, the broken line is inscribed within the peripheral region of the carousel 3.

Conveniently, the forming units 4 comprise a first mold part 5 that is fixed with respect to the carousel 3 and a second mold part 6 that can move on the carousel 3 in translation with respect to the first mold part 5 along a respective movement direction 101.

As in known solutions, the conveyor 22 is associated with at least one oven 22 a for conditioning the preforms 21.

In practice it has been found that the invention is capable of achieving fully the intended aim and objects in all the embodiments.

The operation of the system 1 according to the invention is evident from what has been described above. In particular, the preforms 21 are picked up from the conveyor and transferred to the respective forming unit 4.

Even if forming units 4 that form two forming cavities 11 are used, the feeding of the preforms 21 is extremely practical by virtue of the particular relative movement of the mold parts 5, 6.

This type of movement, moreover, allows to unload easily even large containers 12.

The system thus defined allows advantageously to increase the production rates, increasing the number of forming units 4 on the carousel 3, without increasing the number of cavities as in linear apparatuses.

In this manner, according to what has been described, the lack of increase in the number of cavities in the forming units 4 prevents the lack of uniformity of the temperature of the preforms that can cause inconstant characteristics in the containers obtained during the same forming process.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

In practice, the materials used, so long as they are compatible with the specific use, as well as the shapes and dimensions, may be any according to requirements.

All the details may further be replaced with other technically equivalent elements.

The disclosures in Italian Patent Application No. 102015000084934 (UB2015A009425) from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.