EP0388647B1 - Process and apparatus for closing a package for liquids - Google Patents

Abstract

A process is described for closing a package for liquids having a tube (1), a lid (8) with an opening device (11) and a bottom, the tube (1), the bottom (3, 6) and some wall portions (9, 10) of the lid (8) consisting of plastic-coated paper and the edges of the wall portions (9, 10) of the lid (8) being connected to one another in a fluid-tight manner by sprayed-in bridges made of plastic. <??>For more simple spraying-on of the plastic parts in the lid region in the case of packages, whose lids are at least partially formed by wall portions made of paper, the invention provides for the tube (1), which is open at the lid side and the bottom side, to be laid flat in one plane in a first stage in such a way that at least the lid wall portion (10) for the opening device (11) comes to rest in this plane, then at least the opening device (11) is sprayed on, then in a second stage the tube (11) is opened out together with the opening device (11) and its wall portions (9, 10) are folded over for single-sided closure with formation of the lid (8) and the bridges made of plastic are sprayed in between the thus arranged wall portions (9, 10). <IMAGE>

Description

According to the preamble of claim 1, the invention relates to a method for at least one-sided closing of a liquid pack with tube, lid with opening device and bottom, the tube, the bottom and at least some wall panels of the lid made of plastic-coated carrier material made of paper, cardboard or the like, and the edges of the wall panels of the lid are connected to one another in a liquid-tight manner by means of injected plastic bridges. According to the preamble of claim 3, the invention also relates to such a method, in which liquid packs are closed, the lids of which are not provided with opening devices, but then a handle is fastened in the region of the lid of the pack. Finally, the invention according to the preamble of claim 5 also relates to a device for closing in the manner described above, wherein an injection mold jaw and a counter mold jaw are driven to be movable relative to one another.

It is known to produce liquid packs of the type described, the main body of which is the so-called paper tube. In the case of the packs, the lid and base of which are made by folding from the same paper material, difficulties in opening by the end user have arisen. One has therefore already started to at least inject the plastic cover onto the tube.

It is also known that liquid foods, in particular milk and juices, are packaged aseptically. It is important here that the possible access of oxygen from the environment through the packaging material cannot reach the packaged goods. Paper alone and also for coating it or plastic material used to inject lids or bottoms on its own do not represent a significant barrier to oxygen. For aseptic packs, paper packs provided with a metal layer, for example aluminum, have therefore preferably been used, using the type of pack which had paper walls on all sides, including Lid and bottom.

But if you want better opening devices and still tightness with barrier properties for oxygen, then compromises have to be made, which is why it has already been proposed to produce the tube and the bottom of a paper pack and also to form the lid by means of folded-over wall panels which are formed in one piece with the tube , whereby the edges of these wall panels were connected to one another in a liquid-tight manner by means of injected plastic bridges. In this way it was possible to inject an opening device in the lid area, either in the center or at the edge, e.g. in one of the wall panels, which consist of the tube material and, after the tube has been manufactured and folded over, form the cover from its plane (EP-A-0 223 094).

With such a prior art, there has now been the disadvantage that complicated injection molds have to be used in order on the one hand to spray the bridges onto the edges of the wall panels and on the other hand to form the opening device. The manufacturing processes became even more difficult if such a liquid pack also had a handle which is also at least partially made of plastic and is anchored to the lid, e.g. is injected together with the lid.

Attempts have already been made here to use the appropriate demolding movements in the case of complicated designs using multi-part injection mold jaws, but in practice it has been shown that such machines are particularly susceptible to failure in high-performance operation, ie if several lids with the combination of bridges and / or opening devices and / or Handles had to be created.

The object of the invention is therefore to provide a method of the type mentioned at the outset, with which an easier injection molding of the plastic parts in the lid area is also possible in high-performance operation, in particular in packs whose lids are at least partially formed by paper wall panels.

To achieve this object it is provided according to the invention that the tube, which is open on the cover and bottom, is laid flat in a plane in a first stage such that at least the cover wall field for the opening device comes to lie in this plane; then at least the opening device is injected; thereafter, in a second stage, the tube is unfolded together with the opening device and the wall panels are folded over for at least one-sided closing while creating the cover and the plastic bridges are injected between the wall panels arranged in this way.

It is a prerequisite for this method that the configuration of the bottom of the liquid pack under consideration can be arbitrary. It is further assumed that for the creation of a liquid pack, a tube with the suitable creasing, cutting and folding lines is first created by gluing or sealing along a longitudinal sealing seam from a carrier material web made of paper, cardboard or the like, preferably coated on both sides with plastic. The suitably cut tube is then open on the lid and bottom. In this state, the method for closing the package starts on at least one side of the tube: it is divided into two stages, which ensures the essential simplification of the closing method and the tools required for this. In the first stage, the tube that has just been created is laid flat, taking care that at least that wall field of the lid comes to lie in the plane of the flat tube, which has a Perforation, punching or the like is provided, to which the opening device is to be molded. As can be seen, simple tools can be used, between which the tube lies flat, so that the injection mold jaws can move towards one another as far as the stop, with only a relatively simple recess remaining for the opening device.

In the second stage, which is then provided according to the invention, the flattened tube, which now supports the opening device, is unfolded. In this state, the wall fields initially lying in the plane of the tube are folded along their crease lines or fold lines so that they take up the area of the later cover, and in this form the last spraying process begins, with which the bridges between the wall fields begin Plastic are injected. Here, too, the problem is the same as that described above, so that obviously simple tools can be used for the second spraying process.

If you now want to close at least on one side a similar liquid pack as described above, which also has a tube, but has a flat lid with opening device and a flat bottom, then it is advantageous according to the invention if, in order to create this flat lid, its wall areas by approximately in the second stage 90 ° into the lid level.

In the first proposal of the invention mentioned above, there was the advantage that simple tools are used to attach the opening device to a flat piece of paper in the first stage and the bridges between the wall panels of the cover in the second stage. Obviously, there are particularly simple tools, and the method is also very robust and not susceptible to faults if the lid is to be designed as a level. For the last-mentioned second proposal according to the invention, the two-stage is of course retained, only the wall panels are added folded into the desired cover level, and because this is somewhat perpendicular to the tube, the wall panels must be folded through 90 °.

If it is now desirable, irrespective of the surface shape of the lid, to seal a liquid pack of the type mentioned at the beginning, in which a handle is also fastened in the area of the lid, then according to a further proposal of the invention it is provided that in the first stage the tube is such is laid flat that the anchoring device for the handle on the tube comes to rest on a side edge of the flat tube, and that the handle is molded onto the tube so that the main plane of the handle lies in the same plane as the flat tube. By suitable design of the blank for the tube, it is possible for the anchoring device for the tube on the handle, generally a cut edge, which can be straight, serrated, provided with ears or configured in some other way, to a side edge of the flattened in the manner described Tube. The purpose of this arrangement is to arrange the main plane of the handle in continuation of the flattened tube. Then you can use simple injection molds that have recesses only on the opposite surfaces, in the present case e.g. each for a handle half, because the main plane of the handle is supposed to lie in the same plane as the flattened tube according to the invention.

If, in a preferred embodiment of the invention, a liquid pack is to be closed, which both carries an opening device on a tab or a wall section of the cover and also has a handle, then, in addition to the measures mentioned above, the invention further provides that the handle be used simultaneously the opening device is injected onto the tube. Here again it is irrelevant whether the cover is flat or has the shape of a more or less wide cone.

However, the basic principle of the two-stage process is not abandoned, a distinction being made between the injection options of the opening device and / or handle on the one hand and the possibility of injecting the plastic bridges between the wall panels of the cover. The injection of the bridges should take place in the second stage of the process after the tube has been unfolded, while the injection molding of an opening device or a handle or even both takes place in a first stage in such a way that after the unfolding in the second stage the tube is already with the desired molded parts (opening device, handle) is provided.

The device according to the invention for at least one-sided sealing of a liquid pack with tube, lid and bottom, the tube, the bottom and at least some wall panels of the lid made of plastic-coated carrier material made of paper, cardboard or the like, and the edges of the wall panels of the lid by injection Bridges made of plastic are connected to one another in a liquid-tight manner, starting from US Pat. No. 4,781,012. The device known therefrom has one-piece injection mold jaws and one-piece counter-mold jaws, which each have recesses for an opening device and / or a handle only on the surface facing the other jaw and are driven to be movable relative to one another.

In order to be able to carry out the first and / or second stage of the method described above, it is provided for the device according to the invention that the injection mold jaws and the counter-mold jaws are arranged in the device in at least two groups such that the first group of mold jaws has the recesses for the opening device and / or the handle and the second group of shaped jaws have the recesses for the plastic bridges, through which edges of the wall panels of the lid are connected to one another in a liquid-tight manner.

An essential idea of the present invention is the splitting of the method into a first stage and a second stage, in each of which other measures are carried out. This is reflected in the device in that the mold jaws are arranged in two groups and are divided so that the two process stages can be carried out. This structure of the device is not suggested from the aforementioned prior art, let alone described.

Taking this teaching into account, it is possible for a person skilled in the art to use a simple injection molding machine in spite of relatively complicated lid designs. The skilled person would have little difficulty if only the second step of the process had to be carried out, i.e. only plastic bridges would have to be molded onto the edges of the wall panels of the cover, provided the cover is flat. With a conical design of such a cover, the difficulties encountered by the person skilled in the art can still be overcome.

However, it becomes problematic if apart from the one described Cover formation, an opening device in the lid area or even a handle on the lid should be attached. Here, the invention teaches that one can get by with simple injection mold and counter-mold jaws, which are to be arranged in groups in the machine in such a way that only the opening device or the handle or both are injection molded onto the flattened tube. Such mold jaws can be in one piece and only need to have the recesses provided according to the invention on one surface. After leaving these first mold jaws, the product, ie the tube, is unfolded and fed to a second mold jaw group or station in the overall machine, where the plastic bridges are then molded onto the edges of the wall panels of the lid, again using the same simple tools.

The great advantage of these simple tools is that, particularly in high-performance machines, if you want to close a large number of packs per unit of time in the manner described, several of the simple injection tools described can be arranged one behind the other and moved simultaneously.

Another advantage of the mold jaws arranged and designed in this way is that when several mold pairs are arranged one behind the other, only a force has to be exerted on the outermost mold jaws in order to firmly close all molds at the same time. This closing can be done with great force, because the individual mold jaws are pressed together down to the paper. In other words, the mold jaws support each other over the paper. This allows an exact dimension for the cavities for opening devices, handles, plastic bridges etc. to be maintained. With such a configuration of the mold jaws, it does not occur that the one mold needs to be held in a floating manner at a distance from the other only because a mold cavity has to be predetermined by the tool surfaces alone. In other words, form not actual tool parts arranged on a longer mechanical path, so that the actual mold cavity could also become too small or too large due to tolerances and bending, but according to the invention the paper lies in between because the mold jaws are in place of the mold cavity actually support on paper. All of these advantages result from the flat shape of the tube in the first stage or in the separation of the second injection stage for the plastic bridges of the cover wall panels.

Figur 1

perspektivisch eine erste Ausführungsform einer Flüssigkeitspackung im fertigen und verschlossenen Zustand,

Figur 2

perspektivisch eine andere Form von Verpackung, bei welcher die Öffnungsvorrichtung in der Mitte eines konusförmigen Deckels angeordnet ist,

Figur 3

eine weitere andere Form einer Packung mit Öffnungseinrichtung und Griff in Quaderform,

Figur 4

den flachgelegten Tubus einer hier nicht gezeigten Flüssigkeitspackung und

Figur 5

schematisch den Aufbau eines Hochleistungswerkzeuges für eine Verfahrensstufe, hier die Anspritzung von Öffnungseinrichtung und Griff.

Further advantages, advantageous features and possible applications of the present invention result from the following description in conjunction with the attached drawings. Show it:

Figure 1

in perspective a first embodiment of a liquid pack in the finished and closed state,

Figure 2

perspective another form of packaging, in which the opening device is arranged in the middle of a conical lid,

Figure 3

another other form of a package with opening device and rectangular handle,

Figure 4

the flattened tube of a liquid pack, not shown here, and

Figure 5

schematically the structure of a high-performance tool for a process stage, here the injection molding of the opening device and handle.

From Figures 1 to 4 you can see the tube 1 made of paper coated on both sides with plastic, which is formed by a longitudinal sealing seam 2 to the tube.

In the embodiments of FIGS. 1 to 3, the bottom is square and is formed by folding the wall sections 3, 4, 5, which are partially visible in the tube of FIG. 4, and the transverse sealing seam 6, and is designed flat. From the four corners of the bottom, fold lines therefore run along the tube 1 to the end on the cover side, of which in the embodiments of FIGS. 1 and 2 most of them are only transition fold lines, as shown at 7, because the lid is polygonal in the upper area, it can of course also be round. The cover, generally designated 8, consists in all embodiments of folded-over wall panels 9 and 10, the wall panel 10 each differing from the panels 9 in that it (in the embodiments in FIGS. 1, 3 and 4) with the opening device 11 or in the flattened tube of FIG. 4 is provided with the perforation line 12 for attaching an opening device 11. The special configuration of the opening device 11 is irrelevant to the present description, since various configurations with or without a tear-open handle can be used. The edges 12 between the wall panels 9, 10 are provided with injected plastic bridges 13 according to the schematic cross-sectional illustration in FIG. 2a. In the area of the cover 8, a handle 14 is also injection molded in FIGS. 2 and 3, which in the case of FIG. 1 is only drawn with a broken line and is designated by 14 ', because the attachment of the handle 14' can be dispensed with for practical packaging .

The anchoring device for the handle 14, 14 'results from FIG. 4 with the tube 1 laid flat, because one can see the cutting edge 15 there, which is from the upper, horizontal cutting line 16 at an angle to the longitudinal sealing seam 2 and thus also the longitudinal central axis of the tube 1 runs obliquely outwards down to the area of the bottom 3 - 6. On the length 1, the right edge is to be understood as uncut, because the front and rear surfaces of the tube shown flat in FIG. 4 are connected via this folded edge. In the middle area under the oblique cut edge 15, a triangular ear 17 with a hole 18 can be seen, into which the plastic can extend in a rivet shape when the handle 14, 14 'is molded on, so that the plastic handle 14, 14' is firmly anchored to the paper is.

Figure 5 shows schematically the top view of a group of Mold pairs for performing the method described above. This shows injection mold jaws 19, 19 'or 19''and counter-mold jaws 20, 20' or 20 ''. Three adjacent pairs of jaws can be seen here in a schematic sectional view, the bottom pair being drawn in dashed lines as an indication that more or less of these pairs of shapes can be used in one machine. Each pair of molds is provided in accordance with the arrows 21 shown on the right and can be moved apart or moved together in the direction not shown. FIG. 5 shows the flattened tube 1, exaggeratedly apart, between each pair of jaws 19, 20, it being understood for the reader that the tube is not "flattened" in the spread shape shown, but is actually compressed from above as a line lying flat. Such a line would make viewing and understanding difficult. The dividing line 22 between the respective injection mold jaws 19 and counter-mold jaws 20 also represents the plane 22 'in which the tube 1 comes to rest when it is laid flat in the first process stage. The mold jaws can therefore move in the direction of the arrows 21 and in the opposite direction perpendicular to this plane 22, 22 '. In the collapsed spraying state of FIG. 5, only external forces need to be applied in accordance with arrows 23, 23 'in order to press the mold jaws 19, 20 etc. against one another under the desired pressure. Only the mold cavities 24, 24 ″ for, for example, the opening device 11 and the mold cavities 25, 25 ′ for the handle 14, 14 ′ are left next to the cut edges of the tube 1. The injection channels for the liquid extruded plastic are not shown here, because these details are known to the person skilled in the art from conventional machines.

In operation, the respective pair of jaws 19, 20 is first opened, the tube 1 is positioned lying flat, then the jaws 19, 20 move together, plastic is injected into the cavities 24, 25, cooled, hardened. Then the jaws 19, 20 are moved apart in the direction of the arrows 21, the flat tube 1 is removed and placed in one second stage unfolded in order to be fed to the corresponding tools of a second stage, where the plastic bridges 13 according to FIG. 2a have to be inserted between the edges 12 of the wall panels 9 of the cover 8, whereby the wall panels 9 of the cover 8 are firmly connected to one another.

Claims (5)

1. A method of sealing at least one end of a liquids package, with a tube (1), a top (8) with an opening means (11) and a bottom (3, 6) and at least some of the wall panels (9, 10) of the top (8) consisting of synthetic plastics coated paper, cardboard or like carrier material, the edges (12) of the wall panels (9, 10) of the top (8) being connected to one another in sealing-tight manner by injection moulded bridges (13) of synthetic plastics material, characterised in that the tube (1), open at the top and bottom is in a first stage so laid flat in a plane (22') that at least the top wall panel (10) for the opening device (11) is positioned in this plane (22') whereupon at least the opening device (11) is injection moulded into place, after which, in a second stage, the tube (1) together with the opening device (11) is unfolded and for at least one-sided sealing, its wall panels (9, 10) are folded over to produce the top (8), the synthetic plastics bridges (13) being injection moulded between the thus disposed wall panels (9, 10).
2. A method according to Claim 1, characterised in that to form a flat top (8) in the second stage the wall panels (9, 10) are folded over through about 90° into the plane at the top.
3. A method for sealing at least one end of a liquids package comprising tube (1), top (8) and bottom (3, 6), the tube (1), the bottom (3, 6) and at least some of the wall panels (9, 10) of the top (8) of synthetic plastics paper cardboard or like carrier material and the edges (12) of the wall panels (9, 10) of the top (2) are connected to one another in fluid-tight manner by injection moulded synthetic plastics bridges (13), a handle (14, 14') with an anchoring device (15, 17, 18) being fixed in the region of the top (8) of the package, characterised in that in the first stage the tube (1) is so laid flat that the anchoring device (15, 17, 18) for the handle (14, 14') and the tube (1) is positioned on a lateral edge of the laid-flat tube (1) and in that the handle (14, 14') is so injection moulded onto the tube (1) that the main plane (22') of the handle (14, 14') lies in the same plane (22, 22') as the laid-flat tube (1), and in that subsequently, in a second stage, the tube (1) together with the anchoring device (15, 17, 18) is unfolded and for at least one-sided sealing, its wall panels (9, 10) are folded over to produce the top (8), the synthetic plastics bridges (13) being injection moulded between the thus disposed wall panels (9, 10).
4. A method according to Claim 1 and 3 or 2 and 3, characterised in that the handle (14, 14') is injection moulded onto the tube (1) at the same time as the opening device (11).
5. An apparatus for sealing at least one end of a liquids package with a tube (1), top (8) and bottom (3, 6), the tube (1), the bottom (3, 6) and at least some of the wall panels (9, 10) of the top (8) of synthetic plastics coated paper cardboard or like carrier material, one-piece injection mould dies (19) and one-piece counter mould dies (20) being driven so that they move towards each other, recesses (24, 25) for an opening device (11) and/or a handle (14, 14') being provided only on that surface (22) which is towards the other die (20, 19), characterised in that the injection mould dies (19) and the counter mould dies (20) are so disposed in the apparatus in at least two groups that the first group of mould dies (19, 20) comprises the recesses (24, 25) for the opening device (11) and/or the handle (14, 14') and the second group of mould dies (19, 20) comprises the recesses (24, 25) for the synthetic plastics bridges (13) by which edges (12) of the wall panels (9, 10) of the top (8) are connected to one another in fluid-tight manner.

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