SYSTEM FOR THERMOFORMING SHEET MATERIAL TO OBTAIN CONTAINERS THEREFROM

Abstract: An apparatus comprises indexing means (75) arranged for indexing sheet material (1) along an advancing direction (F) through a forming station (5) in which shells (50, 50a, 50b) of containers (53, 54, 55, 56, 80) joined by undeformed parts of said sheet material (1) are obtained, a filling station (7, 7a) in which said shells are filled with product (52), a shearing station (11) in which said shells (50, 50a, 50b) are severed from said sheet material (1); a method comprises forming sheet material (1) deforming portions thereof so as to obtain shells (50, 50a, 50b) of containers, filling said shells (50, 50a, 50b) with product (52), shearing said shells (50, 50a, 50b) severing them from said sheet material (1); a container comprises a first part of container (50) and a second part of container (50) between which interposing (20) means is peelably interposed.

Description: System for thermoforming sheet material to obtain containers therefrom The invention relates to apparatus, method and container for products, in which thermoforming, filling and joining shells obtained from deformation of a sheet of plastic material are provided. Prior art comprises thermoformed containers for products comprising a base, in which a main portion of product is contained and a lid coupled to the upper peripheral edge of the base by means of welding, or by means of mechanical coupling elements, such as clamps, snap fixing elements, or other. The base and the lid may be substantially equal, or different, to each other the lid being usually less deep than the base. In such containers, the lid and the base may be thermoformed adjacent to each other and joined together by means of a thin strip of plastic material acting as an elastic hinge providing a rotation suitable for allowing the lid to be brought onto the base. The apparatus for the manufacturing of the above mentioned containers comprises a first thermoforming machine, comprising an indexing system for indexing a sheet of plastic material which is caused to pass through a preheating station and subsequently in a forming station in which the sheet is plastically deformed to obtain therefrom a plurality of upper parts of container. In a second thermoforming machine analogous to the first thermoforming machine a plurality of lower parts of container obtained from another sheet of plastic material is thermoformed so as these lower parts of containers may be coupled to the above mentioned upper parts of container obtained by means of the first thermoforming machine. However, before the aforesaid lower parts of container are coupled to the upper parts of container, the lower parts of container have to be filled with product, which took place in a filling station arranged outside of both the first and the sec- ond thermoforming machine. Such apparatuses are very cumbersome and have a very low productivity, mainly since the sheets have to be conveyed in the above-mentioned way so causing remarkable loss of time. In the aforesaid apparatuses, the upper parts of container may be thermoformed from a sheet of material different from the material from which the lower parts of container are thermoformed. Since the two sheets may have different shrinkages, it is possible that, when the sheets are superimposed to each other in order to weld the respective coupling edges, said coupling edges do not match so making the positioning step before welding very difficult, and, if worse comes to worst, the formed containers unacceptable. In further known thermoforming machines, a sheet of plastic machines is thermoformed to obtain lower parts of container each of which is juxtaposed to the upper part of container intended to act as a lid for said lower part and joined to the upper part by a portion of the sheet. After forming, the lower parts of container, each with the upper portion of container associated thereto, are severed from the sheet in a shearing station, filled and finally the upper part of container is brought onto the lower part folding the portion of the sheet like a hinge; the containers so obtained are transferred to the subsequent welding step. This method is rather complicated since, although lid and base of the container may be obtained from the same portion of sheet, said method does not allow the containers to be filled and welded in the same machine in which the forming has taken place, on the contrary, before filling, the containers may be severed from the sheet. Furthermore, in the known thermoformed containers, when the part acting as a lid is removed from the other part, the whole content becomes accessible and so rapidly perishable if it is sensitive to the external environment. An object of the present invention is to improve forming of sheet material. A further object is to provide an apparatus for forming, filling and subsequently welding containers obtained from sheet material . A still further object is to improve the known containers, particularly to improve level of protection of the content. In a first aspect of the invention, an apparatus is provided, comprising a forming station for forming sheet material in which forming means is provided suitable for deforming portions of said sheet material so as to obtain shells of containers joined by not deformed parts of said sheet material, a shearing station in which said shells are severed from said sheet material, characterized in that between said forming station and said shearing station a filling station is interposed in which said shells are filled with product. Between said filling station and said shearing station is interposed a joining station in which sheet material is joined to the edges of said shells, said sheet material causing the product to be isolated from the outside. Preferably, said sheet material shows an intended folding line extending parallelly to an advancing direction of said sheet material . Said portions may define first parts of container arranged on one side of said intended folding line. Furthermore, second parts of container may be defined in said portions on the opposite side of said intended folding line. In this way, base body of containers may be formed, for example, from said first parts of containers and lids of container from said second parts of container, said base body being filled with objects to be packaged. After forming, said sheet material is folded along said intended folding line, so that said first parts and said second parts are caused to match together, and then to undergo the subsequent joining step and shearing step. Therefore, each container is constituted by a first part of container joined along a peripheral edge thereof to a second part of container. In a second aspect of the invention, a method is provided comprising forming sheet material deforming portions thereof so as to obtain shells of containers joined by undeformed parts of said sheet material, shearing said shells severing them from said sheet material, characterized in that before said shearing filling said shells with product is provided. Owing to these aspects of the invention, productivity may be increased and encumbrances may be drastically reduced. In a third aspect of the invention, a container having wall means obtained from sheet material is provided comprising a first part of container having a first peripheral edge region and a second part of container having a second peripheral edge region, said first part of container being joined at its first peripheral edge region to the second peripheral edge region of said second part of container, characterized in that interposing means is interposed between said first peripheral edge region and said second peripheral edge region so as to define a first chamber in said first part of container and a second chamber in said second part of container. Preferably, said interposing means comprises further sheet material removably joined to at least one peripheral edge region selected between said first peripheral edge region and said second peripheral edge region. Advantageously, said interposing means is peelably welded to one, or both, of said first peripheral edge region and said second peripheral edge region. Therefore, the peelable welding which joins the interposing means to the first peripheral edge region may be stronger than the peelable welding which joins the interposing means to the second peripheral edge region. In this way, when the first part of container and the second part of container are removed from each other to open the container, the interposing means is still kept connected to the first part of container, so ensuring protection of the content. Owing to this aspect of the invention, the container may be opened during subsequent steps, at least part of the content being kept protected, if an immediate use thereof is not required. The invention will be better understood and carried out with reference to the attached drawings, which show some exemplifying and not restrictive embodiments thereof, in which: Figure 1 is a front view of an apparatus according to the invention; Figure 2 is a plan view of the apparatus according to the invention shown in Figure 1; Figure 3 is a front view of a second version of an apparatus according to the invention; Figure 4 is a plan view of the second version of an apparatus according to the invention shown in Figure 3; Figure 5 is a broken plan view of a third version of an apparatus according to the invention; Figure 6 is a broken plan view of a fourth version of an apparatus according to the invention; Figure 7 is a plan view of the apparatus shown in Figure 6; Figure 8 is a cross section of the formed film, in a sequence in which the film is folded along a longitudinal middle line in the version of apparatus shown in Figure 5; Figure 9 is a cross section of the formed film, in a sequence in which the film is folded along a longitudinal middle line in the version of apparatus shown in Figures 5 and 6; Figure 10 is a an enlarged and sectioned detail of a container severed from the film of Figure 9; Figure 11 is an enlarged and sectioned detail of a container severed from the film of Figure 8; Figure 12 is a partially broken sequential cross section of the formed film during folding showing keeping means suitable for keeping two halves of the sheet materials folded on each other in a correct relative position; Figure 13, Figure 14, Figure 15 and Figure 17 are cross sections of further versions of container; Figure 16 is a plan view of a longitudinal portion of the formed film; Figure 18 is a left side view of the container of Figure 17; Figure 19 is a view as Figure 17, showing the container closed and filled with liquid; Figure 20 is an enlarged and sectioned detail of forming means; Figure 21 is a detail as in Figure 20 showing another version of the forming means . As shown in Figures 1, 2 and 16, a thermoformable film material 1 is unwound from a reel 2 and is indexed by means of indexing means 75 along an advancing direction F through the stations listed here below: a heating station 3 in which heating means 4 heats the film up to a temperature near to the softening point; a forming station 5 in which forming means 6 deforms portions of the film 1 defining cavities 50 (Figure 8) having a desired shape; a filling station 7 in which the cavities 50 receives products 52 to be packaged; a welding station 8 in which welding means 10 closes the cavities 50 containing the products 52; and a shearing station 11 in which shearing means 12 severs formed, filled and closed containers 53, 54, 56, 80 (Figures 11, 13, 14, 15, 17) from the film 1. The forming means 6 may comprise mechanical forming means, such as drawing means, and/or pneumatic forming means, such as pressurized air delivering nozzles, or sucking nozzle suitable for vacuum forming, or other. In Figure 21 forming means is shown comprising male forming means 60 provided with protrusions 67 insertable into recesses 68 of female forming means 59 in which holes 66 suitable for allowing air discharge are provided. The film to be formed is interposed between the male forming means 60 and the female forming means 59. Conduits 69 are obtained in the protuberances 67 suitable for introducing compressed air through the male forming means 60 for making the film adhere to the recesses 68. In Figure 20 forming means is shown comprising lower case means 61, upper case means 62 and punch means 63. The lower case means 61 and the upper case means 62 clench against opposed faces of a part of the film 1 to be formed. The punch means 63 are slidable at the inside of the upper case means 62 so as to be able to be moved toward, and to be removed from, the film 1 to deform the film 1 causing the film 1 to adhere to appendices 70 which the punch means is provided with. The punch means is provided with openings 71 through which air is sucked, so as to help adhesion of the film 1 to the punch means 63; in order to further help this adhesion, a positive pressurized forming fluid, for example air, is introduced into the region defined by the lower case means 61 and the film 1, in this way the air presses the film against the walls of the punch means 63 causing the film to take the desired shape on. The film 1 is ideally crossed by a line S arranged parallelly to the advancing direction F, said line S longitudinally dividing the film 1 into a first part la of film and a second part lb of film, the first part la and the second part lb being adjacent to each other. The line S may be a folding ideal line, or an incision obtained on the film 1 in order to help folding thereof bringing a part of the film onto the other, or both parts to a joining plane as it will be better described hereinafter As shown in Figures 8 and 9, the film 1, after being formed, may comprise in the first part la of film and in the second part lb of film cavities 50 substantially equal to each other, or first cavities 50a in the first part la of film different from second cavities 50b in the second part of film lb (Figures 12, 13, 4 and 15) . Therefore, a plurality of first cavities 50a may form a plurality of bases of container adjacent to each other, while a plurality of second cavities 50b may form a corresponding plurality of lids of container adjacent to each other. The line S is a folding line along which the film 1 is folded, by means of folding means 9, to bring the plurality of second cavities 50b of container onto the plurality of first cavities of containers 50a. As shown in Figure 16, before the folding means 9 rotates the second part lb of film of 180° around the line S to bring the second part lb of film onto the first part la of film, the film 1 is partially cut along a line 57 transversal with respect to the advancing direction F, said line 57 crossing the second part lb of film up to the intersection of the transversal line 57 with the folding line S. Between the forming station 5 and the folding means 9 the filling station 7 is interposed in which the thermoformed bases 50a of container are filled with product 52; the filling may be automatic or may be performed manually by an operator 58. In the shearing station 11, the thermoformed, filled and closed containers 53, 54, 55, 56, 80 are severed from the film 1 by means of shearing means 12, the shearing means 12 may comprise shaped heated hollow punches, blanking-dies, or longitudinal and transversal cutting blades. In the version of apparatus shown in Figure 3 and 4, a further film 20 is interposed between the first part la of film and the second part lb of film before the welding station 8 so that the further film 20, after welding, is joined to both the first part la of film and the second part lb of film. Advantageously, said further film 20 is peelably welded to the first part la of film and to the second part lb of film and, more in detail, the peelable welding which joins the further film 20 to the first part la of film is stronger than the peelable welding which joins the further film 20 to the second part lb of film. In Figure 3 a filling station 7 is shown, in which all the cavities 50 obtained in the first part la of film and in the second part lb of film are filled with objects 52; downstream of the filling station 7 a reel 21 on which the further film 20 is wound is placed, said reel 21 being arranged with its axis perpendicular to the film 1. The film 1 is folded by deviating means 76 rotating the first part la of film and the second part lb of film around the folding line S and simultaneously lifting the two extreme edges A and B of the film 1 to join said edges A and B along a common vertical plane passing through the folding line S; before the folding of the film 1 is completed, the further film 20 which is drawn from the reel 21 already arranged in a vertical position, is interposed between the first part la of film and the second part lb of film. In greater detail, the film 20 is unwound from the reel 21 and advanced over the film 1, which is in a horizontal position, in a direction perpendicular to the advancing direction of the film 1; near the folding line S an idle roller 81 is placed around which the further film 20 is rotated causing said further film 20 to be contained in the plane passing through the line S and perpendicular to the film 1. Therefore, the film 1 and the further film 20 advance in the same direction, the further film 20 being held between the first part la and the second part lb of film 1 which are rotated in opposed directions until they are placed adjacent to each other in the vertical plane passing through the line S. With reference now to Figures 5 and 6, there is shown an apparatus for manufacturing containers substantially corresponding to the apparatus of Figures 3 and 4, but in which no insertion of further film 20 is provided. More particularly, the apparatus of Figures 5 and 6 comprises, in sequence, the stations listed hereinafter: a heating station 3; a forming station 5, in which longitudinally consecutive halves 50 of container 80 are formed in each part of film la, lb; a welding station 8 in which welding means 10a closes the cavities 50 to form the empty containers 80 leaving therein clear upper openings 64; a filling station 7 in which the container 80 receive a fluid product 78, for example a liquid, to be packaged, which is introduced by means of conduits 79 insertable through the openings 64; a further welding station 8b for closing the openings 64 so sealing the container 80; a shearing station 11 in which shearing means 12 severs formed, filled and sealed containers from the film 1. As shown in Figures 18 and 19, a container 80, which is still joined to the film 1 in the filling station 7a, comprises cavities 50 peripherally joined together by a welding 82 interrupted at the opening 64 and by a hinge 84 arranged at the folding line S. Owing to the apparatus according to the invention, walls may be obtained having a uniform thickness in each region of the container so eliminating dangerous thinning of the walls which are typical of certain known container. Obviously, also the container 80 may be provided with two hollow spaces separated by a further film 20. Figure 5 shows an apparatus for forming container 53, analogous to the apparatus described with reference to Figure 1 and 2, in which downstream of the filling station 7 a reel 21 on which the further film material 20 is wound is provided, said reel 21 being arranged, in this case, with its axis parallel to the axis S of the film 1. The film 1, in which the cavities 50 have been obtained, arrives at a folding station 9 in which the first part la of film, comprising first parts of container 50, is kept horizontal, while the second part lb of film, comprising second parts of container 50 is rotated of 180° to cause first and second part of each container to match together. Before said rotating, the film 20 is arranged, by means of wedge return means, on the first part la of film which is kept in a horizontal position. The two parts of container 50 and the sheet material 20 are welded together in the following welding station 8. During the 180° rotation the objects 52 placed inside the containers might drop; in order to avoid this drawback a mechanic stopping element 33 is provided, shown in Figure 8, said mechanic stopping element 33 being obtained during forming. Due to the mechanic stopping element 33 the object 52 is caused to enter into the container by means of a slight pressure and is then kept in a right position during all the subsequent working operations, until the container is opened. During forming a set of teeth 40 (Figure 12) and a set of notch 41 are obtained in portions of film 1 mutually opposed with respect to the folding line S, for preventing the two portions of film facing each other, particularly the portions arranged far away from the folding line S, from slightly shifting with respect to each other when the first part la has been folded on the second part lb. The teeth 40 and the notch 41 are suitable for engaging to each other allowing the first part la of film and the second part lb of film to be kept face to face in the right position so promoting the welding thereof.

Claims: CLAIMS Apparatus, comprising indexing means (75) arranged for indexing sheet material (1) along an advancing direction (F) through a forming station (5) of said sheet material (1) in which forming means (6) are provided, said forming being arranged for deforming portions of said sheet material (1) so as to obtain shells (50, 50a, 50b) of containers (53, 54, 55, 56, 80) joined by undeformed parts of said sheet material (1), a shearing station (11) in which said shells (50, 50a, 50b) are severed from said sheet material (1), characterized in that between said forming station (5) and said shearing station (11) a filling station (7, 7a) is interposed in which said shells (50, 50a, 50b) are filled with product (52) . Apparatus according to claim 1, and further comprising folding means (9) arranged downstream of said filling station (7) for folding one part (lb) of said sheet material onto another part (la) of said sheet material along an intended folding line (S) parallel to said advancing direction (F) . Apparatus according to claim 1, and further comprising deviating means (76) arranged for folding one part (lb) of said sheet material and another part (la) of said sheet material until they are joined in a common vertical plane passing through an intended folding line (S) parallel to said advancing direction (F) . Apparatus according to claim 3, wherein said deviating means (76) are arranged upstream of said filling station (7a) . Apparatus according any one of claims 2 to 4, and further comprising inserting means (32, 81) arrange for inserting further sheet material (20) between said one part (la) of sheet material and said another part (lb) of said sheet material . 6. Apparatus according to claim 5, wherein said inserting means comprises wedge means (32) extending above said one part (la) of sheet material (1). 7. Apparatus according claim 6, wherein said inserting means (32) is suitable for allowing said further sheet material (20) to extend parallelly to said advancing direction (F) . 8. Apparatus according to one of claims 2 to 7, and further comprising a joining station (10) arranged downstream of said folding means (9), in which said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) are joined together along at least an edge substantial part of containers (80) to be formed. 9. Apparatus according to claim 8, wherein said joining station is a welding station (10) . 10. Apparatus according to claim 9, wherein said welding station (10) is suitable for welding said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) leaving clear upper openings (64) in said containers (80). 11. Apparatus according to claim 10 as appended to claim 4, and further comprising a sealing station (8b) arranged downstream of said filling station and suitable for closing said openings (64) so sealing said containers (80) . 12. Apparatus according to any one of the preceding claims, and further comprising forming means for forming positioning means (40, 41) arranged for substantially preventing said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) from slightly shifting with respect to each other when said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) are placed in contact to each other. 13. Apparatus according to any one of the preceding claims, wherein said forming means comprises forming means for forming stopping means (33) suitable for preventing said product (52) from accidentally coming out from the respective shell (50) . 14. Apparatus according to any one of claims 5 to 13 as appended to claim 2, and further comprising downstream of said filling station (7) cutting means arranged for cutting said another part (lb) of sheet material along a line (57) extending between an edge (B) of said sheet material (1) and said intended folding line (S) . 15. Method, comprising forming sheet material (1) deforming portions thereof so as to obtain shells (50, 50a, 50b) of containers joined by undeformed parts of said sheet material (1), shearing said shells (50, 50a, 50b) severing them from said sheet material (1), characterized in that before said shearing filling said shells (50, 50a, 50a) with product (52) is provided. 16. Method according to claim 15, and further comprising after said filling folding one part (lb) of said sheet material onto another part (la) of said sheet material along an intended folding line (S) parallel to said advancing direction (F). 17. Method according to claim 15, and further comprising folding one part (lb) of said sheet material and another part (la) of said sheet material until they are joined in a common vertical plane passing through an intended folding line (S) parallel to said advancing direction (F) . 18. Method according to claim 17, wherein said folding takes place before said filling. 19. Method according any one of claims 16 to 18, and fur- ther comprising inserting further sheet material (20) between said one part (la) of sheet material and said another part (lb) of said sheet material. 20. Method according to claim 19, wherein said inserting comprises inserting said further sheet material (20) placing said further sheet material (20) above said one part (la) of sheet material (1). 21. Method according claim 20, wherein said inserting is suitable for allowing said further sheet material (20) to extend parallelly to said advancing direction (F) . 22. Method according one of claims 16 to 21, and further comprising, after said folding, joining said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) along at least an edge substantial part of containers (80) to be formed. 23. Method according to claim 22, wherein said joining comprises welding. 24. Method according to claim 23, wherein said welding comprises welding said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) leaving clear upper openings (64) in said containers (80) . 25. Method according to claim 24 as appended to claim 18, and further comprising sealing after said filling for closing said openings (64) so sealing said containers (80) . 26. Method according to any one of the claims 15 to 25, and further comprising forming positioning means (40, 41) arranged for substantially preventing said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) from slightly shifting with respect to each other when said one part (la) of sheet material (1) and said another part (lb) of said sheet material (1) are placed in contact to each other. 27. Method according to any one of claims 15 to 26, wherein said forming comprises forming stopping means (33) arranged for preventing said product (52) from accidentally coming out from the respective shell (50). 28. Method according to any one of claims 19 to 27 as appended to claim 16, and further comprising, after said filling, cutting said another part (lb) of sheet material along a line (57) extending between an edge (B) of said sheet material (1) and said intended folding line (S) . 29. Container having wall means obtained from sheet material, comprising a first part of container (50) having a first peripheral edge region and a second part of container (50) having a second peripheral edge region, said first part of container being joined at its first peripheral edge region to the second peripheral edge region of said second part of container, characterized in that interposing means (20) are interposed between said first peripheral edge region and said second peripheral edge region so as to define a first chamber in said first part of container and a second chamber in said second part of container. 30. Container according to claim 29, wherein said interposing means comprises further sheet material (20) peelably welded to at least one peripheral edge region selected between said first peripheral edge region and said second peripheral edge region. 31. Container according to claim 29, or 20, wherein said interposing means (20) is peelably welded to booth said first peripheral edge region and said second peripheral edge region.

Inventors: MINGHETTI BIANCA ELENA, MINGHETTI, BIANCA, ELENA
Applicants: GREEN PACK S R L, MINGHETTI BIANCA ELENA, GREEN PACK S.R.L., MINGHETTI, BIANCA, ELENA
Application year: 2000
Main classification: B65D75
IPC codes: B29C51, B29L22, B65B3, B65B9, B65B43, B65D1, B65D75