EP1198340B1 - Method for heating the closing flaps of a carton - Google Patents

Abstract

Heating and activation of the base of the folded package material occurs on a mandrel of a mandrel wheel using a hot air nozzle(1) with outlets. The nozzle is moved evenly over the area to be sealed to effect optimum heating of the sealing material. An Independent claim is made for the process equipment which include a rectangular cross-section nozzle (1) with hot air outlets. The nozzle comprises interconnected boxes (2,3,4) with a cover (5).

Description

The invention relates to a method for heating the bottom of composite packages unfolded from packaging jackets, in particular beverage packages, wherein the heating (thermal activation) of the bottom area of the composite package unfolded onto a mandrel of the mandrel wheel to form the package bottom is effected by means of hot air guided through air outlet openings of a heating nozzle, wherein the thermal activation by uniformly guiding over the areas of the package jacket to be sealed during immersion in and out of the package jacket.

Methods for sealing composite packages unfolded from heat-sealable coated packaging jackets by means of thermal activation are known in many forms. The sealing of the package bottoms is done regularly only at the bottler in so-called filling machines. There, the individual packing shells are unfolded and pushed onto mandrels, wherein the mandrels have a rectangular, the later form of the package corresponding cross-section and are arranged evenly radially projecting on a clocked mandrel wheel. To produce the package bottom, the bottom region of the unfolded package jacket is then first heated (thermally activated) in the various positions of the clocked mandrel wheel, then prefolded and finally by means of devices brought to the final shape for final molding and sealed at the same time. Since the packing shells used are already heat-sealable coated, for example, with a thin layer of polyethylene, sealing of the bottom of the package without additional connection medium is possible.

From EP-A1 0 661 211 a method and a corresponding device for sealing packings made of composite material are known, wherein the lid and the bottom are closed by means of press-bonding by thermal activation of the adhesive surfaces with hot air. The hot air is blown through small holes on the activation surfaces. The heater in which the holes are formed consists of an inner and an outer radiator, between which the locking pack is inserted. For uniform distribution of the hot air, the inner radiator is arranged to oscillate. It can be oscillated about the longitudinal and transverse axis of the device during the blowing of the hot air.

From DE-AS 12 44 548 a device for closing of flat folded pieces of tubing upright containers by means of thermal activation is known in which a hot air outlet openings having Heizdüse is brought into a heating position by heating by a cylinder, there the hot air to be sealed Diverts areas of the pack bottom and then pivoted back to the starting position (rest position). The air outlet openings are designed as holes.

Another closure device for containers with a closure of thermoplastic adhesive material is known from DE-AS 15 11 573, in which the heating nozzle also alternately take a rest and a working position to, evenly in time with the mandrel wheel, the area to be sealed thermally activate the bottom of the pack. Here, the air outlet openings are punctiform or slit-shaped. Again, the heating nozzle remains for a certain period of time inside the unfolded packing jacket.

All known devices have the disadvantage that the areas of the package jacket to be heated are heated unevenly. To damage the composite material, especially in composites without aluminum foil, overheating must be reliably excluded so as not to endanger the sealing and gas barrier function. This leads to the fact that in the direct exit region of the hot air, so compared to the air outlet openings, although a sufficient heating takes place, but the heating in the region between the air outlet openings is at least partially insufficient. Although this disadvantage can be partially eliminated by a corresponding geometry of the air outlet openings, but this has a considerable design effort of the heating nozzle result.

Finally, EP-A-0 832 731 discloses a method for bottom formation of composite packs unfolded from packing shells by means of thermal activation, wherein the heating nozzle during heating is performed evenly over the areas to be sealed of the packing jacket. For this purpose, a device with a clocked mandrel wheel and a bottom molding apparatus is provided, which has a substantially corresponding to the shape of the mandrel provided with a rectangular cross-section heating nozzle.

The invention is therefore based on the object, a method of the type mentioned above and described in more detail above and further develop that the quality of the seal can be checked visually.

This object is achieved in that outside of the thermally activated to form the package bottom area additionally at least two thermally activated reference marks are activated at a small mutual distance.

The thermal activation of two adjacent, but spaced reference marks in the non-sealed portion of the package bottom causes the quality of the seal can be optically monitored. The monitoring can be done automatically by a plunging into the open package control optics.

If the reference marks are completely separated after thermal activation, the activation temperature is too low and the floor heating must be set higher. If the reference marks just come together, the activation temperature is sufficient and an optimal operating state is reached. If the reference marks completely merge, so the activation temperature is too high and the floor heating must be set lower. To assess the thermally activated reference marks, the corresponding area can be observed through a polarizing filter on the aluminum-clad side of the packing jacket. The thermally activated areas are colored differently under the polarization filter. The reference marks may be formed, for example, as circular reference points or else as strip-shaped reference bars.

The thermal activation preferably takes place when the mandrel wheel is stationary. According to a further embodiment of the invention, however, the heating nozzle can also be pivoted simultaneously with the mandrel to increase the clock speed during the activation process.

The heating nozzle is moved over the bottom portion of the unfolded packing jacket and the thermal activation occurs during immersion in and out of the packing jacket. Depending on the geometry of the heating nozzle, the bottom area inside and / or outside the packing jacket can be thermally activated. In this way, a particularly good thermal activation can be achieved, since the thermal activation takes place on the one hand shortly before the further movement of the mandrel wheel in the deformation station.

Fig. 1

eine Heizdüse der erfindungsgemäßen Vorrichtung in einer Seitenansicht auf eine Längsseite,

Fig. 2

die Heizdüse aus Fig. 1 in einer Seitenansicht auf eine Stirnseite,

Fig. 3 bis 5

Draufsichten von unten auf die Kästen der Heizdüse aus Fig. 1 und 2 und

Fig. 6 bis 8

Draufsicht auf einen aufgeschnittenen und gerade gefalteten aktivierten Packungsmantel mit optimaler (Fig. 6), zu geringer (Fig. 7) und zu starker (Fig. 8) Aktivierung.

The invention will be explained in more detail with reference to a drawing showing only a preferred embodiment. In the drawing show

Fig. 1

a heating nozzle of the device according to the invention in a side view on a longitudinal side,

Fig. 2

1 in a side view on an end face,

Fig. 3 to 5

Top views from below of the boxes of the heating nozzle of Fig. 1 and 2 and

Fig. 6 to 8

Top view of a cut and just folded activated packing jacket with optimal (Fig. 6), too low (Fig. 7) and too strong (Fig. 8) activation.

From FIGS. 1 to 5, the structurally simple construction of a heating nozzle for the method according to the invention can be seen quickly.

In the illustrated preferred embodiment, the heating nozzle 1 consists of three, each top and bottom open boxes, namely the upper box 2, the middle box 3 and the lower box 4. The lower box 4 is down (packungsinnenseitig) with a lid 5 closed.

The heating nozzle 1 is shown in FIGS. 1 and 2 in its two side views, where the air outlet openings can be seen particularly well, which are partially designed as holes 6 and partially as slots 7.

Figs. 3 to 5 show plan views from below of the individual boxes 2, 3 and 4, wherein in particular the Formation of the nozzle structure in the formed as slots 7 air outlet openings can be seen. It is readily apparent that the design effort for the construction of such a heating nozzle can be made very simple when the slots 7 are arranged respectively at the edges of the individual boxes 2, 3 and 4 respectively.

It goes without saying that the outer dimensions of the individual boxes 2, 3 and 4 corresponds approximately to the inner cross section of a folded-up packing jacket pushed onto a mandrel of a filling machine. The size must be chosen so that between the heating nozzle 1 and (not shown) packing jacket remains a sufficient air gap to reliably exclude bonds or shifts of already thermally activated sealable material such as polyethylene.

For thermal activation, the illustrated heating nozzle, charged with hot air, now "dives" into the region of the packing jacket projecting from the mandrel. In the non-latching in and out movement, the heating nozzle 1 passes over the areas of the package to be activated, so that an extremely uniform thermally activated zone is formed, in which an optimal temperature is adjustable for the subsequent sealing process.

It is readily apparent that the illustrated geometry of the air outlet openings, the holes 6 and 7 slots are selected only by way of example, by corresponding overlapping arrangement, even larger surface areas can heat evenly or even produce different temperature ranges, if they should be necessary for the sealing process.

Finally, it is shown in FIGS. 6 to 8 that the quality of the thermal activation can be monitored optically by means of reference marks provided outside the bottom area to be sealed, but in the bottom of the package. This can also be done fully automatically, with a connected control loop affecting the activation temperature. In the illustrated and preferred embodiment, circular reference points 8, which are generated at a small distance from one another by thermal activation during the activation process, serve as reference marks. It is clear that the distance of the reference marks must be determined empirically for each package format, since factors such as packaging material thickness, aluminum foil thickness, package size etc. play a role here. Although the optical evaluation is done in practice by immersing an optic in the open-topped packing container, in the illustrations according to FIGS. 6 to 8 the bottom region of a packing jacket M is cut open and laid straight.

The visual evaluation of the activation temperature now happens as follows:

The two reference points 8, which are arranged at a small distance from one another in the bottom region of the packing shells, allow, as viewed through a polarizing filter, information about the quality of the seal. If the two reference points 8 are just touching, the activation temperature is set optimally, as can be seen in FIG. If two individual reference points 8 'can be recognized, as shown in FIG. 7, then this is sufficient Activation temperature is not off, it is rather a "underactivation".

The arrows refer to non-thermally activated locations in the bottom area of the cut-up package jacket M to be sealed Fig. 8 shows an unacceptable "over-activation" in which the two reference points 8 "merge into one another Here it can be clearly seen that, in particular in contrast to underactivation in FIG 7 - the activated areas extend over the permissible boundaries in the entire area over the permissible boundaries dot-dashed line or double-line = fold line, at which stage the thermally activated bottom area also tends to form bubbles.

Claims (8)

1. A method for heating the bottom of composite packages that are formed by unfolded package casings (M), in particular, beverage packages, wherein the bottom region of a composite package that is unfolded on a mandrel of a mandrel wheel is heated (thermally activated) by means of hot air that is conveyed through air outlet openings of a heating nozzle (1) in order to form the package bottom, and wherein the thermal activation is realized during the movement into and out of the package casing (M) in the form of a uniform displacement over the regions of the package casing (M) which need to be sealed, characterized in that at least two reference markings (8, 8', 8'') that are mutually spaced apart by a short distance and lie outside the thermally activated region for forming the package bottom are also thermally activated.
2. The method according to Claim 1, characterized in that circular reference points are used as reference markings (8, 8', 8'').
3. The method according to Claim 1, characterized in that strip-shaped reference bars are used as reference markings.
4. The method according to one of Claims 1 to 3, characterized in that the bottom region is thermally activated on the inside and the outside of the package casing (M).
5. The method according to one of Claims 1 to 4, characterized in that the bottom region is thermally activated on the inside of the package casing (M).
6. The method according to one of Claims 1 to 4, characterized in that the bottom region is thermally activated on the outside of the package casing (M).
7. The method according to one of Claims 1 to 6, characterized in that the thermal activation takes place while the mandrel wheel is at a standstill.
8. The method according to one of Claims 1 to 6, characterized in that the thermal activation takes place while the mandrel wheel is turned.