METHOD AND APPARATUS FOR HEAT SEALING CONTAINERS AND FOR FILLING THE SAME

Abstract: A method and an apparatus for manufacturing containers by thermoforming synthetic material in film form and for filling them with a product comprising a step for producing containers by thermoforming at least one strip (3) which is composed of at least two mutually facing films made of heat-sealable synthetic material and in which pockets are formed between the two films, and a step for filling the pockets with a product. The thermoforming step is performed while the at least one strip (3) is arranged on a substantially vertical plane, forming as a whole at least two rows of pockets which are arranged substantially horizontally at mutually different elevations. The filling step is performed while the strips (3), each of which bears a row of pockets, are spaced laterally from each other and are arranged at mutually different elevations.

Description: METHOD AND APPARATUS FOR HEAT SEALING CONTAINERS AND FOR FILLING THE SAME TECHNICAL FIELD The present invention relates to a method and to an apparatus for producing containers by thermoforming synthetic material in film form and for filling them with a product. BACKGROUND ART Apparatuses for manufacturing containers by thermoforming synthetic material in film form and for filling them with a product are known. Said apparatuses generally comprise: a station for feeding a strip composed of two mutually facing films of heat-sealable synthetic material; a station for thermoforming the strip so as to produce a plurality of pockets between the two films; a station for filling the pockets with a product; a station for sealing the pockets and a station for cropping the containers constituted by said pockets. Said apparatuses are provided with means for moving, with an intermittent motion, the strip along a path which runs from the strip feeding station to the cropping station. More particularly, at the feeding station there is a support for reels of film and there are suitable rollers for guiding the film that unwinds from said reels, so as to make two separate films or two flaps of film face each other, either one on top of the other on a horizontal plane or laterally to each other on a vertical plane, according to the type of apparatus. Suitable molds are arranged in the thermoforming station and mutually heat-seal the two films except for preset regions corresponding to the pockets to be formed and to other regions which constitute a channel for connecting the different pockets. In the thermoforming region there are also nozzles for injecting compressed air into the regions that have not been heat-sealed, so as to inflate them and make the two films adhere, in said regions, to the walls that delimit the forming cavities provided inside suitable molds, thus giving the pockets the shape required for the containers to be produced. In the filling station there are suitable dispensing nozzles which, following a movement imparted to the strip which arranges the pockets with respect to the nozzles, are inserted in an opening for accessing the different pockets so as to fill said pockets with the product to be packaged. A station for cooling the packaged product can be interposed between the filling station and the cropping station. In the sealing station, the films are heat-sealed at the opening for accessing the various pockets so as to close said pockets, and in the cropping station suitable cropping molds are provided which cut the strip along the peripheral regions of the different pockets so as to obtain individual containers. In these apparatuses, productivity is strictly linked to the time required to heat-seal the strip composed of the two films in order to obtain the different pockets and to crop the containers; said speed cannot be increased beyond a certain limit which is imposed by the technological and production process. In order to increase the production capacity of these apparatuses, a plurality of rows of pockets are generally thermoformed simultaneously on a same strip composed of two mutually facing films and arranged on a horizontal plane. Thermoforming a plurality of rows of pockets on a strip which is arranged on a horizontal plane and is subsequently divided into a plurality of strips, one for each row of pockets, entails the problem of requiring, before the different strips enter the filling station, the twisting of each strip so as to arrange said strips on parallel vertical planes, owing to the fact that the filling of the different pockets must generally be performed vertically. Moreover, said twisting is difficult to achieve in confined spaces if the films of synthetic material used are thicker than 0.3 millimeters. DISCLOSURE OF THE INVENTION The aim of the present invention is to provide a method and an apparatus for producing containers by thermoforming synthetic material in film form and for filling them with a product which allow to achieve high productivity despite having in-line space dimensions which are comparable to those required by conventional apparatuses. Within the scope of this aim, an object of the invention is to provide a method and an apparatus which can be used without problems both with thin films and with relatively thick films, i.e., thicker than 0.3 millimeters. Another object of the invention is to provide a method and an apparatus which allow to fill containers vertically. Another object of the invention is to provide a method and an apparatus which do not entail penalizing production rates with respect to conventional apparatuses. This aim, these objects and others which will become apparent hereinafter are achieved by a method for manufacturing containers by thermoforming synthetic material in film form and for filling them with a product, comprising a step for producing containers by thermoforming at least one strip which is composed of at least two mutually facing films made of heat-sealable synthetic material and in which pockets are formed between said two films, and a step for filling said pockets with a product, characterized in that said thermoforming step is performed while said at least one strip is arranged on a substantially vertical plane, forming as a whole at least two rows of pockets which are arranged substantially horizontally at mutually different elevations, and in that said filling step is performed while said strips or strip portions, each of which bears a row of pockets, are spaced laterally from each other and are arranged at mutually different elevations. In order to perform the method according to the invention, an apparatus is preferably used which comprises: means for feeding at least one strip which is composed of at least two mutually facing films made of heat-sealable synthetic material; means for moving said at least one strip along an advancement path; a station for thermoforming said strip in order to form a plurality of pockets between said two films; a station for filling said pockets with a product; and a station for sealing said pockets; characterized in that said thermoforming station comprises thermoforming molds which are arranged vertically and in which forming cavities are provided which are arranged along at least two horizontally arranged rows and at mutually different elevations, and in that between said thermoforming station and said filling station means are provided for conveying and guiding said strips or strip portions, each of which supports one of said rows of pockets, along substantially vertical planes which are mutually laterally spaced and are arranged at mutually different elevations. BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will become apparent from the following detailed description of a preferred but not exclusive embodiment of the method according to the invention and of the apparatus for performing it, both of which are illustrated by way of nonli itat ive example in the accompanying drawings, wherein: Figure 1 is a schematic lateral elevation view of an apparatus for performing the method according to the invention; Figure 2 is a schematic top plan view of the apparatus of Figure 1; Figure 3 is a schematic view of a strip, composed of two films made of two mutually facing films made of heat- sealable synthetic material, at the outlet of the thermoforming station; Figure 4 is an enlarged-scale view of a detail of Figure 2 related to the filling station; Figure 5 is a perspective view of a detail of the conveyance and guiding means; Figure 6 is a partially sectional view of a detail of the- apparatus related to the filling station, taken along a direction which is parallel to the advancement direction of the strips or strip portions, at said station; Figure 7 is a view of a portion of the strip shown in Figure 3, illustrating the regions that are cropped at the end of the method according to the invention; Figure 8 is a front view of a detail of the cropping station. WAYS OF CARRYING OUT THE INVENTION With reference to the above figures, the apparatus for performing the method according to the invention, generally designated by the reference numeral 1, comprises: a station 2 for feeding at least one strip 3 composed of at least two mutually facing films 4 and 5 made of heat-sealable synthetic material; means for moving the strip 3 along an advancement path; a thermoforming station 6; a filling station 7; and a cropping station 8. More particularly, at the feeding station 2 a frame 10 is provided which supports, so as to allow rotation about their respective horizontally arranged axes, at least one reel, preferably an active reel 11 and a reserve reel 12, whereon a film made of thermoformable synthetic material is wound; said film is cut into two equal parts, obtaining two mutually facing films 4 and 5 made of thermoformable synthetic material . As an alternative, the film that unwinds from the reel 11 or from the reel 12, instead of being cut, can be folded in a U-shaped manner in order to still obtain two films 4 and 5 which face each other despite being joined at one of their longitudinal sides. Suitable and appropriately inclined guiding rollers 13 and 14 are arranged in the feeding station 2 so as to move the two films 4 and 5 that unwind from the reel 11 or from the reel 12 onto a vertical plane at the inlet of the thermoforming station 6. Heat-sealing molds 17 are provided, in a per se known manner, in the thermoforming station 6 and are arranged substantially vertically; said molds are actuated so as to heat-seal the two films 4 and 5 except at least for the regions whereat the pockets 15, which will constitute the containers to be produced, are to be obtained, and at other regions in order to form suitable ducts 16 with branches which mutually connect the different pockets 15, as shown in particular in Figure 3. Thermoforming molds 18 are arranged in the thermoforming station 6; forming cavities are provided in them, arranged along at least two horizontally directed rows, and lie at mutually different elevations so as to match the regions excluded from the heat-sealing action performed by the molds 17. In a per se known manner, in the thermoforming station 6 there are also nozzles for dispensing compressed air which are gradually inserted into the ducts 16 formed earlier, so as to inject compressed air into the pockets 15, accordingly inflating them and making them adhere to the walls of the forming cavities provided in the thermoforming molds 18, in order to obtain, at the outlet of the thermoforming station 6, a strip in which at least two rows of pockets 15 are formed, three rows of pocket 15 in the illustrated embodiment, said rows being arranged horizontally and being mutually superimposed vertically. Directly downstream of the thermoforming station 6 there are advancement means 20, such as for example groups of conventional grippers, which are not described further for the sake of simplicity, and cyclically engage the strip 3 in order to make it advance intermittently along a path which runs from the feeding station 2 to the cropping station 8. According to the present invention, between the thermoforming station 6 and the filling station 7 there are means for conveying and guiding the strip portions, each of which supports a row of pockets 15, so as to feed the filling station 7 with strip portions 3a, 3b, 3c which are arranged mutually side by side on substantially vertical planes and at mutually different elevations. Directly upstream of the conveyance and guiding means, in the illustrated embodiment, there is at least one cropping blade 21 which acts on regions of the strip which lie between the different rows of pockets 15 and intersects the upper end of the pockets 15, at least of the pockets 15 arranged in the lower row in the case of two rows of pockets 15, so as to form an opening for filling said pockets 15. The conveyance and guiding means comprise guiding and/or advancement rollers, designated by the reference numerals 22, 23 and 24, which have vertical axes and are superimposed and mutually offset. Said guiding rollers 22, 23 and 24 engage the strip portions 3a, 3b, 3c produced by cropping, each of which bears a row of pockets 15, and form, at least at the filling station 7, different paths for the strip portions 3a, 3b, 3c which are arranged mutually side by side on substantially vertical planes and at mutually different elevations. The guiding and/or advancement rollers 22, 23 and 24 conveniently have, on their lateral surface, a plurality of recesses 25 which are meant to accommodate the pockets 15 so as to not compress them during this step. In the filling station 7 there are dispensing nozzles 26 which are fed with the product to be packaged in the pockets 15 and are arranged along at least two horizontal rows which are arranged mutually side by side and are located at elevations which are different one from the other. The nozzles 26 are mounted on a dosage pump 27 and the strip portions 3a, 3b, 3c are guided, at the filling station 7, by a structure 80 which can oscillate about a horizontal axis 81 which is parallel to the advancement direction of the strip portions 3a, 3b, 3c so as to slightly lift the strip portions 3a, 3b, 3c so as to produce the insertion or extraction of the nozzles 26 through the opening for filling the pockets 15. After the filling station 7 it is possible to provide a cooling station 30 comprising at least one enclosure which internally forms a refrigerated chamber 31 in which there is a path for one or more of the strip portions 3a, 3b, 3c lying along a double spiral inscribed in a rectangle. In the illustrated embodiment there are three cooling chambers 31, one for each one of the portions 3a, 3b, 3c into which the initial strip 3 is divided. A buffer storage device 38 can be provided between the filling station 7 and the cooling station 30 in order to compensate for any differences in the operating speed of the cooling station 30 with respect to the filling station 7. A sealing station 40 is arranged between the cooling station 30 and the cropping station 8, and at said sealing station conventional heat-sealing means are provided, which are not illustrated for the sake of simplicity, which act on the filling openings of the different pockets so as to close them. Upstream of the sealing station 40 there are rollers 60 which return the various strip portions 3a, 3b, 3c onto a single substantially vertical plane. The cropping station 8 comprises a blanking mold 50 which acts on a substantially vertical plane and cyclically crops the strip portions 3a, 3b, 3c along the perimeter of the pockets 15 arranged in the various rows, so as to separate them from the remaining part of the strip 3 that constitutes process waste. The blanking mold 50 is served by an intermittent floating star-shaped device 55 with suckers 55a for picking up and releasing the cropped containers onto a conveyor belt 56. Operation of the illustrated apparatus in performing the method according to the invention is as follows. The strip 3, composed of two films 4 and 5 that arrive from the reels 11 and 12 and arranged on a substantially vertical plane, is subjected, in the thermoforming station 6, to heat-sealing except for preset regions which are meant to constitute the pockets 15 and except for regions whi-ch are meant to constitute the ducts 16 for connecting the different pockets 15 to each other. Injection of compressed air into said ducts 16 inflates the pockets 15 and shapes them inside the forming cavities provided for this purpose inside the thermoforming molds 18 arranged in the station 6, obtaining at least two rows of pockets 15, three rows in the illustrated case, which lie horizontally and are arranged at mutually different elevations. At the outlet of the station 6, the portions 3a, 3b, 3c of the strip 3, each of which supports a row of pockets 15 and is arranged at mutually different elevations, are separated by the cutter 21 and, by means of the rollers 22, 23 and 24, are spaced from each other laterally. In the filling station 7, the dispensing nozzles 26 are inserted in the filling opening of the individual pockets 15, following the lifting of the strip portions 3a, 3b and 3c, and the product is inserted into said pockets. Subsequently the strip portions 3a, 3b, 3c are conveyed into the cooling chambers 31, and at the outlet of said chambers, after the strip portions have been returned to a same substantially vertical plane, the filling opening of the various pockets 15 is sealed in the sealing station 40. Finally, the various pockets 15 are cropped, accordingly forming individual containers, by means of the blanking mold 50 which is arranged at the cropping station 8 . Finally, the individual containers are picked up and placed on the conveyor belt 56 by the device 55. It should be noted that it is possible to feed the thermoforming station 6 with a single strip 3 which is then divided by the cutters 21 into two or more strip portions, each of which contains a row of pockets 15, as described so far, or to feed individual strips which are arranged substantially vertically and at mutually different elevations and are supplied by individual reels or are produced by horizontally cutting a single strip ahead of the thermoforming station 6. In practice it is possible to supply the thermoforming station 6 with a single strip which is then divided into strip portions, each of which contains a row of pockets, or to feed multiple strips or strip portions which are arranged at mutually different elevations and on a same substantially vertical plane and are meant to bear one or more horizontal rows of pockets 15. Feeding a plurality of strips or strip portions arranged on a same vertical plane and at mutually different elevations does not exclude the possibility to perform further cutting of these portions so as to in any case obtain, at the inlet of the filling station 7, a plurality of strips or strip portions, each of which contains a row of pockets 15 which are laterally offset with respect to each other and are arranged at mutually different elevations. It should be noted that in an extreme case, if the thermoforming station 6 is fed with a plurality of strips or strip portions, said strips or strip portions can also be mutually laterally offset by means of conveyance and guiding means similar to the ones that have already been described and arranged upstream of the thermoforming station 6, although this inevitably increases, albeit to a lesser extent than described earlier with reference to conventional apparatuses, the complexity of the production of the heat-sealing and thermoforming molds. In practice it has been found that the method and the apparatus according to the invention fully achieve the intended aim, since in-line space occupation being equal, they allow to achieve a distinctly higher productivity than obtainable by conventional apparatuses. The method and the apparatus thus conceived are susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with other technically equivalent elements. In practice, the materials employed, as well as the dimensions, may be any according to requirements and to the state of the art. The disclosures in Italian Patent Application No. MI97A002736 from which this application claims priority are incorporated herein by reference.

Claims: CLAIMS 1. A method for manufacturing containers by thermoforming synthetic material in film form and for filling them with a product, comprising a step for producing containers by thermoforming at least one strip (3) which is composed of at least two mutually facing films (4, 5) made of heat-sealable synthetic material and in which pockets (15) are formed between said two films (4, 5), and a step for filling said pockets (15) with a product, characterized in that said thermoforming step is performed while said at least one strip (3) is arranged on a substantially vertical plane, forming as a whole at least two rows of pockets (15) which are arranged substantially horizontally at mutually different elevations, and in that said filling step is performed while said strips (3) or strip portions (3a, 3b, 3c), each of which bears a row of pockets (15), are spaced laterally from each other and are arranged at mutually different elevations. 2. A method according to claim 1, characterized in that said thermoforming production step is performed on two or more strips (3) or strip portions (3a, 3b, 3c) which are mutually superimposed on a same substantially vertical plane. 3. A method according to claim 1, characterized in that said thermoforming production step is performed on a single strip (3) arranged on a substantially vertical plane. 4. A method according to claims 1 and 3, characterized in that said strip (3), after said thermoforming production step, is cut into multiple strip portions, one for each one of said rows of pockets (15). 5. A method according to claim 4, characterized in that the cutting of said strip (3) into a plurality of portions is performed at one end of the pockets (15) of the various rows in order to form an opening for filling said pockets ( 15 ) . 6. A method according to one or more of the preceding claims, characterized in that after said filling step the product introduced in said pockets (15) is cooled. 7. A method according to one or more of the preceding claims, characterized in that after said filling step the opening for filling said pockets (15) is closed. 8. A method according to one or more of the preceding claims, characterized in that after closing the filling opening of the pockets (15) the containers formed by said pockets (15) are cropped from the remaining part of the strips (3) or strip portions (3a, 3b, 3c). 9. A method according to one or more that of the preceding claims, characterized in that before said cropping step the strips (3) or strip portions (3a, 3b, 3c) that bear the rows of pockets (15) are returned to a substantially co-planar position. 10. A method according to one or more of the preceding claims, characterized in that before said cropping step the strips (3) or strip portions (3a, 3b, 3c) that bear the rows of pockets (15) are returned to a substantially co- planar position on a substantially vertical plane. 11. An apparatus for producing containers by thermoforming synthetic material in film form and for filling them with a product, comprising: means (2) for feeding at least one strip (3) composed of at least two mutually facing films (4, 5) made of heat-sealing synthetic material; means (13, 14) for moving said at least one strip (3 ~ ) along an advancement path; a station (6) for thermoforming said strip (3) in order to form a plurality of pockets (15) between said two films (4, 5); a station (7) for filling said pockets with a product; and a station (40) for sealing said pockets (15); characterized in that said thermoforming station (6) comprises thermoforming molds (17) which are arranged vertically and in which forming cavities are provided, said cavities being arranged in at least two horizontally-directed rows and at mutually different elevations, and in that between said thermoforming station (6) and said filling station (7) there are means (22, 23, 24) for conveying and guiding said strips (3) or strip portions (3a, 3b, 3c), each of which bears one of said rows of pockets (15), along substantially vertical planes which are laterally spaced from each other and at mutually different elevations. 12. An apparatus according to claim 11, characterized in that it comprises means (21) for cutting said strip (3) into a plurality of strip portions, one for each one of said rows of pockets (15), said means (21) being arranged between said thermoforming station (6) and said conveyance and guiding means (22, 23, 24). 13. An apparatus according to claims 11 and 12, characterized in that said cutting means comprise a cutting blade (21) which acts on a region of said strip (3) which lies between two rows of pockets (15) and intersects the upper end of at least the pockets (15) arranged in the lower row so as to form an opening (16) for filling said pockets ( 15) . 14. An apparatus according to one or more of the preceding claims, characterized in that said conveyance and guiding means comprise guiding and/or advancement rollers (22, 23, 24) which have vertical axes and are mutually superimposed and laterally offset, said guiding and/or advancement rollers (22, 23, 24) engaging said strips (3) or strip portions (3a, 3b, 3c) and forming, at least at said filling station (7), different paths for said strips (3) or strip portions (3a, 3b, 3c) arranged mutually side by side and at mutually different elevations. 15. An apparatus according to one or more of the preceding claims, characterized in that recesses (25) are formed in the lateral surface of said guiding and/or advancement rollers (22, 23, 24) at the regions meant to make contact with said pockets (15). 16. An apparatus according to one or more of the preceding claims, characterized in that dispensing nozzles (26) are arranged at said filling station (7) and are supplied with the product to be packaged into said pockets (15), said nozzles (26) being arranged along at least two horizontal rows arranged mutually side by side and located at elevations which are different one from the other. 17. An apparatus according to one or more of the preceding claims, characterized in that it comprises, at said filling station (7), a structure (80) for guiding the strip (3) or strip portions (3a, 3b, 3c), said guiding structure (80) being movable in order to lift said strips (3) or strip portions (3a, 3b, 3c) with respect to said nozzles (26) to insert or extract said nozzles (26) through the pocket filling opening. 18. An apparatus according to one or more of the preceding claims, characterized in that downstream of said filling station (7) along the advancement direction of said strips (3) or strip portions (3a, 3b, 3c) along said path there is a station (30) for cooling the product introduced in said pockets (15). 19. An apparatus according to one or more of the preceding claims, characterized in that a buffer storage device (38) is arranged between said filling station (7) and said cooling station (30). 20. An apparatus according to one or more of the preceding claims, characterized in that downstream of said cooling station (30) along the advancement direction of said at least one strip (3) or strip portions (3a, 3b, 3c) along said path there is a station (8) for cropping the containers from said strips (3) or strip portions (3a, 3b, 3c), a blanking mold (50) being provided in said cropping station (8), being arranged on a substantially vertical plane and acting simultaneously on the pockets (15) that belong to different strips (3) or strip portions (3a, 3b, 3c) in a substantially co-planar position. 21. An apparatus according to one or more of the preceding claims, characterized in that in said cooling station (30) at least one enclosure is provided which internally forms a refrigerated chamber (31); a path being formed in said chamber (31) for one or more of said strips (3) or strip portions (3a, 3b, 3c), said path being arranged along a spiral which is inscribed in a rectangle.

Inventors: ACCORSI MARCO, ACCORSI, MARCO
Applicants: ACCORSI MARCO, TRIMAT SRL, ACCORSI, MARCO, TRIMAT S.R.L.
Application year: 1998
Main classification: B65B1
IPC codes: B65B9, B65B43