Molding system for producing containers and corresponding molding method

Abstract

The invention relates to a molding system (10) for producing containers (6a) starting from a tubular thermoplastic material (6), comprising: an upper mold (1) equipped with two first molding shells, a lower mold (2) equipped with two second molding shells, a pair of additional compression elements (3) acting on the two first shells of the upper mold (1) during the closing and filling stage of the upper mold (1), exerting additional pressure in the direction of the arrow (3a) to ensure the proper sealing of the container, the upper mold (1) and the lower mold (2) being movable with respect to each other so as to invert their respective positions.

Description

[0001] MOLDING SYSTEM FOR THE PRODUCTION OF CONTAINERS AND RELATED

[0002] MOLDING PROCESS

[0003] *****

[0004] The present invention falls within the field of production of liquid-filled containers in parison form, wherein, in a stage defined as the “blowing” stage (BLOW), the plastic is extruded in a tubular form which, through a pressure difference exerted on its wall, adheres to the walls of a mold to form the container. In the subsequent “sealing” stage (SEAL), the container is closed by sealing specific sections of the container, and, before performing the final seal, which closes the opening through which the container can be filled, a filling stage (FILL) may be provided, wherein the container can also be filled with a liquid via a movable nozzle.

[0005] Field of the invention

[0006] Specifically, it is a machine for the blow molding of containers, containers in a continuous process, wherein a tubular plastic material is extruded continuously from an extrusion head and subsequently formed by a series of molds; subsequently, the formed tubular form is filled, and / or one or more components are inserted inside it, and then sealed by a further mold.

[0007] Prior art

[0008] Patent DE1964862C3 describes a machine consisting of an extrusion head and two groups of opposite molds, which move alternately in a vertical direction, and which can open like a book, in a horizontal direction, by rotating on a lateral vertical pin.

[0009] This machine appears to have several problems, including the following.

[0010] Since opening the molds requires rotating them on a lateral pin, it is necessary that the lower mold must open in such a way as not to hit the closed mold in order to move into the upper position.

[0011] This book-style opening also requires a lot of free space on the sides of the machine and increases its overall size.

[0012] A further problem is that during the container forming process, it is necessary to apply a very high force - parallel to the closing direction of the molds - to compress the plastic material to ensure that the opposite sides are welded together and sheared. This force must be applied to the centre of the portion of the mold that forms a single container, so that it is distributed uniformly. Since in the aforementioned patent the molds are closed by rotating them on a lateral pin, this is impossible.

[0013] Finally, during the opening of the molds, the newly produced containers may remain stuck to the mold, posing a risk of breakage or, in any case, weakening of the containers themselves.

[0014] Aim of the invention

[0015] The main aim of the present invention is to provide a machine that overcomes the aforementioned drawbacks and that in particular allows for the production of a plurality of containers using a continuous process, in an easy and straightforward manner.

[0016] In detail, the aim of the invention is to create a machine of the type mentioned above that allows a continuous molding cycle to be carried out, without any interference or collision between the molds.

[0017] Another aim of the present invention is to obtain a forming and detachment of the containers suitable for ensuring their integrity, reducing the risk of breakage and / or weakening.

[0018] Object of the invention

[0019] The object of the invention is therefore a molding system for the production of containers starting from a tubular thermoplastic material, comprising an upper mold equipped with two molding halves or first molding shells laterally supported, a lower mold equipped with two molding halves or second molding shells laterally supported, wherein the upper mold and the lower mold are movable with respect to each other so as to invert their mutual positions, and a pair of additional compression elements capable of switching from a first active condition, wherein it acts on the two first shells of the upper mold during the upper mold closing stage, exerting additional pressure to ensure the proper sealing of the container, to a second inactive condition, wherein no pressure is applied.

[0020] Specifically, in the non-active condition, the pair of additional compression elements may comprise two mechanical compression elements separated from the upper mold and the lower mold so as not to interfere with the reciprocal inversion movements between the upper mold and the lower mold. This advantageously allows the force to be centred from time to time exactly at the centre of gravity of the containers to be formed, or in any case where necessary, even in the case of replacement of the molds with others of a different shape or size. Preferably, according to the invention, the upper and lower molds close and open independently of each other, maintaining both the respective first and second shells parallel to each other in both reciprocal positions, allowing the thermoplastic tubular form to move between them.

[0021] Thus, advantageously, it is possible to save space compared to the bookstyle opening, according to which the respective shells are not parallel to each other when opened.

[0022] Further, according to the invention, the pair of additional compression elements is decoupled from the molds, in other words: it moves vertically independently of the molds.

[0023] This allows for a single additional compression mechanism for the two lower and upper molds.

[0024] A further object of the invention is a container engagement system for engaging containers that came out of a mold of a molding system - for example, but not limited to, of the type described above - comprising first grippers and / or second grippers connectable to the upper mold and / or lower mold respectively, which open and close and move vertically in conjunction with the respective upper and / or lower molds to engage containers that came out of the adjacent mold.

[0025] In this way it is possible to prevent breakages or deformations of the containers when the mold is opened.

[0026] Furthermore, according to the invention, first spacers can be provided which are adapted to create a space, between the first grippers and the upper mold, with a length greater than or equal to the height of the lower mold, and / or second spacers can be provided which are adapted to create a space, between the second grippers and the lower mold, with a length greater than or equal to the height of the upper mold.

[0027] In this way, the reciprocal movement between the lower and upper molds is advantageously guaranteed during the various continuous molding stages.

[0028] Furthermore, in such cases, the first spacers can be positioned laterally with respect to the upper mold, and the second spacers can be positioned laterally with respect to the lower mold and in an opposite position to the first spacers, to avoid interference during the movements for exchanging position of the two molds.

[0029] A further object of the invention is an alignment system between the upper and lower mold for a molding system - for example, but not limited to, of the type described above - comprising first alignment slides connected at the top and / or bottom of the two first shells of the upper mold, and second alignment slides connected at the top and / or bottom of the two second shells of the lower mold, the first alignment slides being adapted to cooperate with the second alignment slides so as to keep the upper mold and the lower mold aligned with each other.

[0030] Another object of the invention is a molding process implemented by a machine for molding containers starting from a thermoplastic tubular form extruded from an extrusion head and equipped with a molding system as described above, wherein during the molding cycle, the pair of additional compression elements opens when the upper mold has completed molding of the upper container, allowing the lower mold to move upwards and take the place of the upper mold.

[0031] Alternatively, the molding process may involve inserting a component into the container by passing through the extrusion head and using a rod, before the upper mold is closed.

[0032] According to another alternative, the molding process may involve inserting a component into the container by passing through the extrusion head and using nozzles, before the upper mold is closed.

[0033] In addition, according to the invention, the process may include inserting an insert into the container by using a rod, before the upper mold is closed.

[0034] Brief description of the figures

[0035] The present invention will now be described, by way of example and not as a limitation, according to some of its preferred embodiments, and with the aid of the attached figures, wherein:

[0036] Figure 1 a is a sectional view of the continuous cycle molding system of the invention, in a first molding stage;

[0037] Figure 1 b is a sectional view of the continuous cycle molding system of the invention, in a second molding stage;

[0038] Figure 1 c is a sectional view of the continuous cycle molding system of the invention, in a third molding stage;

[0039] Figure 1 d is a sectional view of the continuous cycle molding system of the invention, in a fourth molding stage;

[0040] Figure 1 e is a sectional view of the continuous cycle molding system of the invention, in a fifth molding stage; Figure 1f is a perspective view of a first shell of the upper mold of the molding system of Figures 1 a-1 e;

[0041] Figure 1 g is a perspective view of the two lower and upper shells of Figures 1a-1e;

[0042] Figure 1 h is a front view of the two lower and upper shells, highlighting the alignment slides between molds;

[0043] Figure 1 i is an enlarged front view of the mold alignment slides;

[0044] Figure 2a is a sectional view of a first variant of the continuous cycle molding system of the invention, in a first molding stage;

[0045] Figure 2b is a sectional view of the continuous cycle molding system of Figure 2a, in a second molding stage;

[0046] Figure 2c is a sectional view of the continuous cycle molding system of the invention shown in Figure 2a, in a third molding stage;

[0047] Figure 2d is a sectional view of the continuous cycle molding system of the invention shown in Figure 2a, in a fourth molding stage;

[0048] Figure 2e is a sectional view of the continuous cycle molding system of Figure 2a, in an alternative fourth molding stage;

[0049] Figure 3a is a sectional view of a second variant of the continuous cycle molding system of the invention, in a first molding stage;

[0050] Figure 3b is a sectional view of the continuous cycle molding system of Figure 3a, in a second molding stage;

[0051] Figure 3c is a sectional view of the continuous cycle molding system of the invention shown in Figure 3a, in a third molding stage;

[0052] Figure 3d is a sectional view of the continuous cycle molding system of the invention shown in Figure 3a, in a fourth molding stage.

[0053] Detailed description

[0054] In the various figures, similar parts will be indicated by the same numerical references.

[0055] With reference to Figures 1 -3, a molding system 10 is shown, comprising an upper mold 1 equipped with a mold head 1.1 and a mold body 1.2 (in Figure 1f the respective movable half is shown independently of the other half), and a lower mold 2, which mirrors the upper mold 1 and equipped with a mold head and a mold body (not shown in the figure) integral with each other. According to the invention, there is a pair of additional compression elements 3 which, during the closing and filling stage of the upper mold 1 (Figs. 1 a and 1 b, 2a and 2b, 3a and 3b), acts on the two shells of the upper mold 1 itself to exert additional pressure on the mold in the direction of the arrow 3a, in order to ensure the proper sealing of the container.

[0056] This additional compression mechanism 3 is capable of applying this force 3a to close the molds uniformly and centrally with respect to the container.

[0057] This additional compression mechanism 3 is decoupled from the molds so that only one of these mechanisms is sufficient for both molds.

[0058] This mechanism can also move in a direction parallel to the direction of descent of the molds, moving from an upper position, where it is aligned with the closing height of the upper mold, to a lower position, where this mechanism opens. This vertical movement is necessary to ensure that it can follow, during the compression stage, the mold that is compressing, allowing this compression to be applied for a longer time.

[0059] The extrusion head 4, through which it is possible to insert the nozzles 5 into the parison tubular form 6, is above the molding system.

[0060] The upper mold 1 and the lower mold 2 close and open alternately, their respective shells remaining parallel to each other, and once the molding by the upper mold 1 is complete, the pair of additional compression elements 3 opens (Fig. 1 c) and can begin to return to the upper position. Meanwhile, the upper mold 1 continues to follow the movement of the parison 6, moving closed downwards and passing through the open shells of the lower mold 2, which meanwhile move upwards (Figs. 1 d-1 e, 2d).

[0061] These shells of the upper and lower molds are laterally supported by the supports 1 .5

[0062] A feature of the present invention, which solves one of the problems described above, is the closing / opening movement of the molds which is performed in a direction perpendicular to the vertical movement. This movement advantageously reduces the overall dimensions of the machine.

[0063] Once the lower mold 2 has taken the position of the upper mold 1 (Fig. 1 e) and vice versa, the molding cycle can resume: since reference will be now made to a stage wherein the lower and upper molds are inverted, only in the next paragraph the upper mold - now in the lower position - will be indicated by the numerical reference 2, and the lower mold - now in the upper position - will be indicated by the numerical reference 1 .

[0064] The lower mold 1 closes around the parison tubular form 6 while the additional compression elements 3 exert their additional pressure on it according to the arrow 3a to improve the sealing of the lower part of the container (Fig. 1 a); the nozzle 5 lowers and dispenses the liquid into the container, while at the same time the additional compression elements 3 and the upper and lower molds 2 and 1 lower themselves following the parison 6 along its flow (Figure 1 b); once the sealing is complete, the additional compression elements 3 open and return to the upper position while the molds 1 and 2 continue to lower themselves (Fig. 1 c); the upper mold 2 opens, releasing the completely formed container, and returns upwards, while the closed lower mold 1 continues to descend together with the parison through the open shells of the upper mold 2 (Fig. 1 d); finally, the lower mold 1 and the upper mold 2 return to their original position and the additional compression elements 3 approach the respective shells of the latter in preparation for closing (Fig. 1 e).

[0065] From now on, the upper mold will be designated by the reference number 1 and the lower mold will be indicated by the reference number 2.

[0066] In a preferred variant of the invention, grippers can be provided connected respectively to the upper mold (indicated in the figures by the reference 1 .3) and to the lower mold (indicated in the figures by the reference 2.3), which follow the opening and closing of the respective molds, so as to engage the containers 6a that came out of the respective mold in the previous cycle.

[0067] This further innovation allows the stage of removal of the vials from the mold to be facilitated. The gripping system is connected to the respective mold, therefore it opens / closes and moves vertically together with the mold to which it is connected.

[0068] In this way, when the lower mold 2 opens (Fig. 1 d) the container formed by this mold is held in place by the grippers 1.3 that are still closed together with the upper mold 1 and adjacent to the lower mold 2 itself.

[0069] In fact, the empty space between the grippers 1.3 and the upper mold 1 corresponds at least to the height of the lower mold 2, just as the distance between the grippers 2.3 and the lower mold 2 corresponds at least to the height of the upper mold 1 , so that the movements for exchanging position of the two molds 1 and 2, equipped with their respective grippers, do not interfere with each other. Preferably, these aforementioned distances correspond exactly to the height of the upper mold 1 and lower mold 2 respectively, subject to the necessary clearances for the actual movement between the parts, in order to make the system 10 as compact as possible.

[0070] Of course, the first connection element 1 .4 between the grippers 1 .3 and the upper mold 1 must also be positioned laterally with respect to the parison tubular form (as shown in Figure 1f), and the second connection element between the grippers 2.3 and the lower mold 2 must be positioned laterally with respect to the parison tubular form and in an opposite position with respect to the first connection element 1 .4 so as not to collide during the movements for exchanging position.

[0071] In other words, with reference to Figure 1f, the shells of the upper mold 1 each have a C-shaped configuration (only one is shown in the figure, but it is to be understood that the other is exactly symmetrical), wherein the head of the mold 1.1 , the body of the mold 1 .2 and the grippers 1 .3 are parallel, while the first connection element 1 .4 is transversal to them.

[0072] The lower mold 2 has a similar C-shaped configuration, but symmetrically opposite, so as to allow reciprocal movements for exchanging position between the mold shells.

[0073] As shown in Figures 1 h and 1 i, the two upper mold halves 1 could have alignment slides 1 .6-1 .7 that interface respectively with the slides 2.6-2.7 present in the lower mold halves 2. In particular, the lower slides 1 .7 of the upper mold halves 1 have first sliding surfaces 1.8 facing upwards, while the upper slides 2.6 of the lower mold halves 2 have second sliding surfaces 2.8 facing downwards. In this way, the lower slides 1 .7 of the upper mold halves 1 interface with the upper slides

[0074] 2.6 of the lower mold halves 2, specifically due to the mutual sliding of the first and second sliding surfaces 1 .8 and 2.8. These surfaces ensure that the two mold halves remain aligned during the descent in case there are minor deformations or misalignments of the main structure. These slides are advantageously fixed laterally, thus allowing the molds to slide through these slides in an alternating manner to allow the proper operation of the machine without jamming.

[0075] Similarly, the upper slides 1 .6 of the upper mold halves 1 and the lower slides

[0076] 2.7 of the lower mold halves 2 also have respective sliding surfaces 1.8 and 2.8 facing respectively downwards and upwards and towards each other. In particular, the absence of end stops allows for mutual sliding and release when it is necessary to release the upper and lower molds 1 and 2 and invert their relative positions.

[0077] Operationally, the extrusion head 4 extrudes a plastic material with a tubular form 6. Figures 1 a, 2a and 3a show the machine in a first forming stage, wherein the molds 1 and 2 are closed and aligned by means of the slides.

[0078] At this stage the pair of additional compression elements 3 is in the closed position and is applying a force 3a, to compress and shear the plastic material 6.

[0079] In a subsequent stage, depicted in Figures 1 b-1 d, filling occurs through the nozzles 5.

[0080] In a particular configuration, shown in Figures 2b-2d, after the filling stage (Fig 2a), the nozzles 5 could rise above the head 4, and subsequently, the rods 8, on whose tip a respective insert 7 can be positioned (Fig 2b), could descend (Fig 2c) to place this insert within the container before the upper mold closes (Fig 2d).

[0081] In detail, the insert 7 is placed on the top of the already formed (and potentially already filled) container, subsequently the rod 8 rises, and the process continues. In this case the insert is part of the lower container.

[0082] In another particular configuration shown in Figure 2e, this insert 7 can be positioned in the middle of the upper mold, with the rod 8 remaining down during the closing of the upper mold, embedding the insert 7 within the upper container.

[0083] In particular, the insert is held raised in a position above the head portion of the upper mold by the rod 8 and the upper mold closes around it, then the rod rises, leaving the insert embedded in the mold. In this configuration, the insert becomes part of the upper container.

[0084] In the next stage, shown in Figures 1 c and 2c, the pair of additional compression elements 3 opens. Subsequently, as shown in Figures 1 d and 2d, the lower mold 2 opens, sliding with its upper slides 2.6 along the lower slides 1 .7 of the upper mold 1 until it is released from the latter. It can also be noted that the lower grippers 2.3 open together with the lower mold 2, while the upper grippers 1.3 remain closed, since they are connected to the upper mold 1 .

[0085] Finally, it is possible to restart the cycle, as shown in Figure 1 e, with the lower mold 2 moving to the upper position, while the upper mold 1 is in the lower position, and they align with each other by means of the slides 1 .6 and 2.7. Of course, both techniques for inserting inserts could be used in combination, by adding another system of rods 8, allowing for the insertion of one insert positioned above the lower vial and, subsequently, another insert positioned below the upper vial during the cycle.

[0086] In an alternative embodiment, this component 7 could be inserted through the nozzle 5 itself.

[0087] Of course, the same cycle is also possible in the presence of double molds, such as those shown in Figures 3a, 3b, 3c and 3d: the pair of closing elements 3 acts on the first upper mold 1 (Fig. 3a), then on the second upper mold 1 a (Fig. 3b), and in the meantime the two lower molds 2 and 2a open to move upwards and pass over the upper molds 1 and 1 a (Fig. 3c), and then exchange positions as shown in Fig. 3d.

[0088] The invention thus conceived and illustrated here is susceptible to numerous modifications and variations, all of which fall within the scope of the inventive concept.

[0089] Furthermore, all the details may be replaced by other technically equivalent elements.

[0090] Finally, the components used, as long as they are compatible with the specific use, as well as the dimensions, may be chosen as needed according to the requirements and the state of the art.

[0091] Where the features and techniques mentioned in any claim are accompanied by reference signs, these reference signs have been included with the sole purpose of enhancing the intelligibility of the claims and, consequently, these reference signs do not have any limiting effect on the interpretation of each element identified by way of example by these reference signs.

Claims

1. A molding system (10) for producing containers (6a) from a tubular thermoplastic material (6), comprising: an upper mold (1) containing two first molding bodies, a lower mold (2) containing two second molding bodies, wherein the upper mold (1) and the lower mold (2) are configured to move relative to each other, ensuring the ability to change their respective locations, and a pair of elements (3) for applying additional clamping, configured to transition from a first working state, in which they act on the first two bodies of the upper press mould (1) at the stage of its closing, exerting additional pressure (3a) to ensure proper sealing of the container, to a second non-working state, in which no pressure is exerted.

2. The system according to claim 1, in which said pair of elements (3) for applying additional clamping is separated from the upper mold (1) and the lower mold (2) with the prevention of obstruction of said reciprocating movements of the upper mold (1) and the lower mold (2) to be able to change their places.

3. The system according to claim 1 or 2, in which the upper mold (1) and the lower mold (2) close and open independently of each other, holding the corresponding first and second bodies of said molds parallel to each other, ensuring movement of the thermoplastic tubular blank (6) between them.

4. The system according to one of paragraphs 1-3, in which the said pair of elements (3) for applying additional clamping moves vertically independently of the press molds.

5. A container gripping system (1.3, 2.3) designed to grip containers (6a) emerging from a mold of a molding system according to one of claims 1-4, comprising first grippers (1.3) and / or second grippers (2.3) that are configured to be connected to an upper mold (1) and / or a lower mold (2), respectively, and that open and close and move vertically together with the corresponding upper mold (1) and / or lower mold (2) to grip containers (6a) emerging from an adjacent mold.

6. The system (1.3, 2.3) according to item 5, comprising first spacer elements (1.4) intended to form a space between the first grippers (1.3) and the upper mold (1) and having a length that is greater than or equal to the height of the lower mold (2), and / or second spacer elements (2.4) intended to form a space between the second grippers (2.3) and the lower mold (2) and having a length that is greater than or equal to the height of the upper mold (1).

7. The system (1.3, 2.3) according to claim 6, in which the first spacer elements (1.4) are located laterally relative to the upper mold (1), and the second spacer elements (2.4) are located laterally relative to the lower mold (2) in a position opposite to the first spacer elements (1.4), in order to avoid interference during movements when the two molds (1, 2) change places.

8. An alignment system between the upper mold (1) and the lower mold (2) for the molding system according to one of claims 1-4, characterized in that it comprises first alignment guides (1.6, 1.7) connected from above and / or below to the two first bodies of the upper mold (1), and second alignment guides (2.6, 2.7) connected from above and / or below to the two second bodies of the lower mold (1), wherein the first guides (1.6, 1.7) are designed with the possibility of interacting with the second guides (2.6, 2.7) to keep the upper mold (1) and the lower mold (2) aligned with each other.

9. A method of moulding carried out by a machine for moulding containers from a thermoplastic tubular blank (6) extruded from an extrusion head (4) comprising a moulding system according to one of claims 1-3, in which during the moulding cycle said pair of elements (3) for applying an additional clamp is opened when the upper mould (1) has completed moulding the upper container, with the possibility of opening the upper mould (1) and moving the lower mould (2) upward to the place of the upper mould (1).

10. A method of moulding carried out by a machine for moulding containers from a thermoplastic tubular blank (6) extruded from an extrusion head (4) comprising a moulding system according to one of paragraphs 1-3, in which, before the upper mould (1) closes, a component (7) is inserted into the container by passing it through the extrusion head using a rod (8).

11. A molding method performed by a machine for molding containers from a thermoplastic tubular blank (6) extruded from an extrusion head (4) containing a molding system according to one of paragraphs 1-3, in which, before the upper mold (1) closes, a component (7) is inserted into the container by passing it through the extrusion head using nozzles (5).