MX2008007373A - Shrinking process for producing solid, transportable and printable containers and device for carrying out said shrinking process - Google Patents

Abstract

The invention relates to a shrinking process for producing solid, transportable andprintable containers, especially bottle containers with a height/width ratio of>1 and containing heat-sensitive filling substances. The shrinking process comprises the steps of covering the containers to be packaged with a film in such a manner as to produce an overlapping section of the film ends on the bottom surface, heating them by heat transfer or convection, thereby fusing together the free ends in the area of overlap, and then finally heating the containers in a shrinking oven, the container so produced being stabilized by the shrinking process. The incoming hot air is first locally limited to the bottom surface of the container in order to form a peripheral shell in the area of the bottle bottoms and the shape of the container is stabilized while the container is continuously transported during stabilization. The hot air directed onto the bottom area of the container in a bundle of discretely distributed gas jets is discharged and returned after a locally limited heat transfer with the film. More hot gas is directed laterally onto the continuously transported container at an increased lateral blow speed in order to complete the shrinking process.

Description

METHOD OF RETPOSITION FOR THE PRODUCTION OF SOLID, TRANSPORTABLE AND PRIMARY ATTACHMENTS AND DEVICE FOR THE REALIZATION OF A SIMILAR METHOD OF RETRACTION. DESCRIPTION OF THE INVENTION The invention relates to a shrinkage method for the production of solid, transportable and printable bundles, in particular bundles of bottles with a height / width ratio of > 1, consisting of wrapping the goods by packaging with a film so that an overlapping region of the ends of the film is formed in the floor area, heating by heat transfer, respectively, convection to merge the overlapping region and a final heating in which the bundle in progress is simultaneously stabilized by the retraction process. Retraction methods for the production of solid, transportable and printable bundles are nowadays realized in many ways in the film packages that are used as a commercial unit for bottles. The film also serves as an advertising vehicle, for example, in the case of beverage bottles that are wrapped with a shrinkable film. Hot gases in which thermal energy is transmitted are usually used to heat the shrink films.

Convection to the surface of the material to be heated. WO 02/36436 A1 discloses a multi-zone retraction tunnel comprising a pre-retraction zone with air from the heated environment and a zone of strong heat, where hot-air-wrapped articles are applied at the end stage to the articles wrapped in film. The articles are assembled in this first in groups, preferably using a solid transport helmet, and wrapped in a film. The ends of the film that overlap in the floor of the bundle are sealed by applying hot air over a wide area and subjected to a final retraction process after a previous retraction process. In order for the finished bundles to be printable they must have constant dimensions and flat surfaces. The printable surface must also offer sufficient resistance against the contact of the print roller during printing, since otherwise a blurred printed image is generated. These requirements result in bundles with the same spatial dimension and reproducible relative positions of the articles transported. It has been found that particularly in the transport during the packing of articles with a high center of gravity as, e.g., bottles with a height / width ratio clearly > 1, preferably > 2, the Items that have a vertical position in the overlap region of the film ends tend to change their relative position to the other objects by rollover. The inevitable vibrations and shakes of the bundle in the production process and during the transport cause an instability and irregularity of the retraction during the retraction process. It has been attempted, therefore, to produce bundles with a uniform spatial dimension and reproducible relative positions of the objects with each other. But as these are massive products with relatively low part prices, the separate introduction of a helmet for the production of particularly stable bundles can not be considered because of the greater economic use of matter and energy. In the case of certain products, heating of the entire product is allowed only in a limited manner, e.g., in the case of foods such as chilled dairy products or beverages mixed with carbon dioxide which are under pressure. Therefore the shrinkage temperatures have been reduced, which increased the duration of the process. In addition, lower temperatures caused problems in the weld, so that the required strength in the wrapping of the bundle was not always achieved. The inventors further detected that a sealing of the film ends at lower temperatures it certainly avoids a significant heating of the articles themselves, but is accompanied in particular by the continuous transport of the bundles due to the problem that the film, when receiving a lateral hot air jet, fills with air and slips. This intensifies the already described tendency of individual objects of the articles to pack to overturn respectively change their position. The object of the present invention was, therefore, to offer a retraction method as well as a device for performing the retraction method which allows without a separate carrier helmet the production of a solid tether of articles having a height proportion of width of > 1, preferably > 2, with a density and uniform geometric shape, where the individual articles are heated superficially, if at all. In the case of units that only need or can be heated superficially, this means that the temperature of the core must be kept low and the emission of energy to the average environment must be reduced. Other aspects are space requirement, process control with flexible bundle sizes and the reduction of exposure of the average environment by emission gases of film materials. This objective is achieved through a method of retraction according to claim 1, as well as a device for carrying out the retraction method according to claim 7. Other advantages result from the dependent claims and the following description. Thanks to the new retraction method, an efficient energy transfer could be achieved, where the coefficient of heat transition between the media, respectively, participating materials, the type and size of the heated surface in each case, and the current velocity of the hot gas they were optimized by the entire surface of heat transfer, respectively, convection surface, as well as the exchange of cases with the environment. By means of certain measures it was possible to keep the temperature of the core low and locally weld the packing film thanks to the narrow delimitation of the high temperatures, the individual objects (articles to be packed) being heated briefly only on their surface to the required shrinkage temperature . It was also possible to reduce the emission of temperature to the medium environment because the hot air used to weld the overlapping ends of the film in the region of the floor was directed only on the surface of the floor of the bundle and, therefore, was limited to this zone. Thanks to this it was possible to achieve a stabilization of the shape of the bundle by in situ formation of a shell marginal, so that the articles already from the beginning of the process of retraction were fixed in their mutual position. Thanks to this, the tied stabilized already on the surface of the floor resisted when receiving a jet of hot air laterally with higher loads, so that the blowing process could be limited to a short duration of treatment. Simultaneously being produced the advantage in the continuous transport, in particular in the bundles with a large placement surface, which could prevent an accumulation of heat due to the hot air applied in the center of the placement area, respectively an impermissible heating of the articles for packing. Until now there was a risk that the side parts of the bundle were heated by the hot air that runs everywhere and had an irregular influence on the retraction process of the wrapping film. This problem could be solved thanks to the fast continuous transport of the bundle in a network structure with a zone exposure of the hot air floor surfaces. For this, hot air is introduced into gas jet beams discretely distributed to a convection zone that is delimited on one side by the floor of the bundle and on the other by the air exhaust openings. The incoming hot air is diverted under an action reciprocally intimate with the film on the floor of the bundle and fed back to the gas circuit system in the reverse direction of current. This form of driving the hot gas will be referred to hereinafter as an inversion current. By means of a parallel movement of the convection zone and the tying floor with different speeds it is achieved that the convection zone during the transport of the bundle slowly accompanies the entire floor surface without causing an accumulation of heat or an irregular retraction of the film on the sides of the bundle. By means of a particular line of the gas in the form of an inversion current, a heat transition is made in a defined convection zone of the hot gas to the floor surface of the bundle. The application of energy per zone can be optimally adapted in this way to the thickness of the material or the density of the film by controlling the current velocity of the hot gas and optimally form on the heat transfer surface, respectively, of convection exactly definable. The advantages mentioned in the foregoing are achieved inventively in a surprisingly simple and inexpensive manner. The invention is explained in detail below by means of several exemplary embodiments. It shows: Fig. 1 the principle structure of a retraction facility for the production of solid, transportable and printable bundles (front view and side view). Fig. 2 Perspective view of an inventively configured retraction device. Fig. 3 Principle representation for the reversal current and formation of a marginal shell by a cross section through an air exchange plate Fig. 4 Transport of a tie by an inventively configured device for applying hot gas to the floor region of the bundle Fig. 5 Perspective view of the device for hot gas application. Fig. 6 General view of the device for the formation of a marginal shell Fig. 7 Structure of an inventively configured device for the formation of a marginal shell Fig. 8 Scheme of the method of the inventive method for the production of solid, transportable and printable bundles. In the upper part of FIG. 1, the inventive device for performing a retraction method in a front view is shown. The system 5, 7 of entry and exit of air with the attached 1 that is arranged above a source 3 of hot air. The hot air, applied in reversing current (see the arrow directions in Fig. 3) serves to configure a pre-stabilized marginal shell 32 in the region of the bundle floor. In the right part of FIG. 1, the bundle 1 is shown in an installation having a side supply of hot air. The articles (bottles) of the bundle are transported through a conveyor belt 6 in the direction of product advance through the retraction facility 4. As soon as the bundle 1 arrives with the wrapping film 8 facing the hot air supply 5 there is a risk that the film wrapping will be inflated by the air pressure and threatens to come out of its position. This is prevented by the marginal shell previously formed in the region of the floor of the bundle that stabilizes the shape of the bundle and thereby the arrangement of the articles. In the lower section of FIG. 1, the retraction device is shown in a side view, an air outlet system 7A, 7B being indicated on the left side of the installation laterally next to the hot air source 3. The exhaust air is brought in circuit for the hot air treatment, respectively, completely or partially recycled, so that an accumulation of hot air can be avoided in collaboration with continuous transport. The nozzles 5a are shown on the right side of the retraction system, 5b of hot air acting horizontally. They initiate the process of retraction everywhere in the bundle enclosed by an enveloping film. In the perspective representation according to FIG. 2, the two sections (formation of the marginal shell, retraction finish) are shown analogously to FIG. 1. Below the conveyor belt is the supply with hot air as the inverting current. In the convection region, the network-like structure of the conveyor belt 2 is partially covered by slides 10, 11. In this way it is ensured that only the floor surface 12 of the transported bundle or of a partial region receives incoming current. of hot air (accompanying convection zone). In section 4 of the installation the hot gases come out with great pressure from nozzles 5 arranged laterally. The current velocity can be further increased and constantly oriented on the entire surface of the film 8, since the bundle has been stabilized on the floor surface in such a way that the film 8 folded over the articles 13 in the form of bottles withstands a large lateral pressure load. Thanks to a subsequent cooling by means of ventilation with cold air (not shown), the synthetic material from the plastic area is transferred to the elastic area, increasing the maximum stresses in the material and this solidifies. On the other hand, the film is still retracted in this cooling, so that the stresses increase even more and the clamping forces that stabilize the bundle reach the required magnitude. In an environment with excessive heat, it is necessary to actively cool down, since the ambient air temperature is not sufficient for solidification. In the context of the partial cross section shown in FIG. 3 through an air exchange plate, the principle of the reversal current will be explained below: The tie 1 is placed on a structure 9 in the form of a network or grating, so that the hot air leaving the nozzle field 33 through the nozzle 14 has access to a convection zone 15 of the conveyor belt 6. In the convection zone 15 the heat transition of the hot gas is carried out by convection to the floor surface 12 of the bundle. After the deviation in the surface of the bundle floor, the hot gas flows in the direction of the arrow through suction openings 16, 17 back to the exhaust air region. Fig. 4 shows the transport of the bundle 1 by an air exchange plate 29 configured inventively according to the principle of the reversal current, having a convection zone 15 for the formation of a marginal shell. In this case, the intake air 5 is diverted to the exhaust air system 7a, 7b. The zone control of the longitudinal and transverse slides 23, 26 is not shown. This is necessary to be able to achieve the accompanying movement of the convection zone and the floor surface 12 of the bundle avoiding an accumulation of heat. In the left margin of the picture, a preferred variant of the inventively configured air changing plate 29 is shown in the partial cross section of FIG. 5 to blow hot air discreetly in the region of the tying floor. The air exchange plate 29 contains sliding ribs 31 on which the conveyor belt 18 rests in the form of a net. The bundle 1 contains a multiplicity of products 19 wrapped by a shrinkable film 20. When the transport of the bundle 1 is performed in the direction of the arrow above the air changing plate 29, then the air units 21 of the air are controlled. inlet and the exhaust air units 22 by transverse and longitudinal slides in the form of registers. This control, which is also called "zone activation", is represented in FIGS. 6 and 7 and is described in detail below: The activation of zones can be carried out manually or by automatic control. In the example according to FIG. 6, it is attached 1 is transported in the direction of the arrow above the conveyor belt 18 in the form of a network to the area of reach of the source 3 of hot air (vertical arrow). In the examples shown here, the longitudinal slider 23 is adjusted manually. This can be done by means of an eccentric adjustment 24 according to FIG. 7. In the transverse direction, the adjustment of the slides is controlled by a zone activation by means of which the transverse slides 26 activate or deactivate the supply of air according to the position of the valve. product, respectively, of the bundle 1 on the conveyor belt 18. To control the activation of zones, according to the exemplary embodiment, a perforated plate is required as a transverse slide 26, as well as tubes 27 for the supply of hot air and a separation box 28 for the intake and exhaust air. . From the previous example it shows how the hot gas is conducted in the inventive device for the formation of a stabilizing marginal shell according to the principle of the inversion current. The heating surface is represented by an air exchange plate comprising a particular gas line in which the gas is transferred from an open circuit system to a closed one. In the heating surface, there is a field of notches, for example, in the form of a channel or bell, with an intake air unit in the form of a nozzle having a very small distance to the top of the bell being arranged in the center of each bell. surface to be heated. On one side of the bell is one or more exhaust air units in the form of suction openings whose diameter and number is selected such that the incoming intake air is sucked after the deviation in the floor surface of the tether . In the context with the partial cross-section by a sliding plate, according to FIGS. 3 and 5, the reversal current can be explained by a principle representation. The bundle 1 is in a structure 9, respectively, 10 in the form of a net or grid, so that the hot air leaving a notch respectively hood has an access to the convection zone 15. In the convection zone 15, the heat transition of the hot gas is carried out by means of Convection to the floor surface of the bundle. After deflection on the surface of the bundle floor, hot gas flows through the suction openings 16, 17 back to the exhaust air region. With this provision it is ensured that the notches or, in the present case, the hoods are always completely covered or at least on the edge completely by the floor of the bundle. Thanks to the inversion current, the influence of air shortage is minimized. Even with the use of less energy and a smaller amount of intake air the formation of a stabilizing marginal shell is achieved. This is true even in the case of a parallel relative movement of object and heating surface, since the convection zone accompanies the movement. The inventive device is controllable in large sections of the convection zone. For this, an area with the desired energy requirement is fed by temperature and current profiles that the user can predetermine as a function of the route. The energy requirement is calculated or determined empirically according to the thickness of matter, the density of matter or the thermal capacities of the film that must be heated. According to this the film can be deliberately tempered.

A schematic summary of the steps of the method in the retraction is shown in Fig. 8 appended. In this it means: 1. Wrapping the bundle with a film 2. Shaping the floor region with the overlapping ends of the film 3. Blowing hot air, driven in inversion current, with 200 to 210 ° overlap 4. Period of stop by zone until melting the film, duration 1 to 2 seconds 5. Stabilization of the shape of the bundle by forming a marginal shell in the region of the floor 6. Full retraction of the film by side blowing with hot air at an increased pressure 7. Blow cold air to solidify the film By cooling in the last stage of the method is transferred, on the one hand, the synthetic material from a plastic area to an elastic area, which increases the maximum stresses in the material and solidifies in this. On the other hand, the film is still retracted during this cooling, so the tensions increase in the film and the clamping forces that stabilize the bundle grow. In the case of a hot environment it is necessary to actively cool, since the ambient air is not sufficient for solidification.

List of reference symbols in the description 1 Tied 2 Conveyor belt 3 Hot air source 4 Retraction system 5 Hot air supply a) Hot air nozzles b) Hot air nozzles 6 Conveyor belt 7 Exhaust air system a) Exhaust air system b) Exhaust air system 8 Film 9 Network structure 10 Slide 11 Slide 12 Floor surface 13 Bottle-shaped articles 14 Nozzle 15 Convection zone 16 Suction opening (Fig. 3), sliding plate (Fig. 5) 17 Suction opening (Fig. 3), sliding rib (Fig. 5) 18 Conveyor belt in the form of a net 19 Products (Fig. 5); Entrance air inlet area (Fig. 6) 20 Shrinkable film 21 Intake air nozzles 22 Exhaust air nozzles 23 Longitudinal slide 24 Eccentric adjustment 25 Activation of zones 26 Transverse slide Perforated plate 27 Tubes 28 Separation box 29 Plate air exchange 30 Sliding plate 31 Sliding nerves 32 Marginal shell 33 Nozzle field

Claims (12)

1. Shrinking method for the production of solid, transportable and printable bundles, in particular of bundles of bottles having a height to width ratio > 1 and with heat sensitive content substances, consisting of wrapping the articles by packing with a film so that a region of overlap of the ends of the film is formed on the floor surface, a heating by heat transfer respectively convection for joining the free ends in the overlap region by casting, and a final heating in a retraction furnace in which the tying process is stabilized by the retraction method, characterized in that the incoming hot air is first limited by area to the surface of tied floor for the formation of a marginal shell of the bottle floors and the tied is stabilized in this in its form, the bundle is transported continuously during the stabilization and the hot air, directed in this in a beam of gas jets discretely distributed against the region of the floor of the bundle, is diverted and returned after a limited heat transfer by zone with the film, and because in the retraction furnace additional hot gas is oriented with a lateral blow speed increased against the tied that continues being transported continuously, to complete the process of retraction. Retraction method according to one of the preceding claims, characterized in that the film * is welded to form a tying floor and is simultaneously retracted and a positive-bonding conformation of the tying floor surface is generated therein. Retraction method according to one of the preceding claims, characterized in that the bundles are moved in a transport device during the welding method, the incoming hot air being sucked in after the heat transfer and controlled therein in such a way that the welding it is limited to the overlapping region or a partial area of the floor. Shrinking method according to one of the preceding claims, characterized in that the zone application is carried out by activating discretely distributed intake and exhaust units which are mechanically, hydraulically or electrically controllable. Retraction method according to one of the preceding claims, characterized in that a low pressure is formed in the exhaust unit which is sufficient to accelerate the hot air of the intake unit in the overlapping region and guide it with speed increased on the ends of the film to be welded. Retraction method according to one of the preceding claims, characterized in that the control of the intake and exhaust units is carried out by transverse and longitudinal slides, with individual units of the intake and exhaust units discretely distributed according to the zone application being activated. of the film ends in the overlap region. 7. Device for the realization of a retraction method for the production of solid, transportable and printable bundles, in particular of bundles of bottles with a height-to-width ratio > 1 and with substances of heat sensitive content, consisting of a packaging machine in which the items to be packed are wrapped in a film, heated and then packed in a retraction oven forming a solid bundle, the bundles being moved during the heating on a conveyor belt, characterized in that the conveyor belt has a network-like structure, with admission and exhaust air units arranged in a discretely distributed manner in the heating region below the conveyor belt; the retraction region nozzles of hot air are directed with an increased blow speed against the bundles, and because below the network structure the intake and exhaust air units are provided with transverse and longitudinal slides arranged in the form of registers for the zone delimitation of the hot air stream to the floor region of the floor. the tied ones. Device according to claim 7, characterized in that the intake and exhaust air is conducted below the conveyor belt in a closed circuit. Device according to claim 7 or 8, characterized in that each intake and exhaust air unit is arranged in a recess in a sliding plate and because the intake and exhaust air units necessary for heating the surface of floor are freely controlled in the form of notches discretely distributed in the sliding plate by transverse and longitudinal slides, arranged in the form of registers. Device according to claim 7, 8, 9, characterized in that the recesses are configured as bells or channels. Device according to one of the preceding claims, characterized in that the gas stream is configured as an inversion current in which the current velocity of the hot gas is inverted after the heat transfer with the floor surface. Device according to one of the preceding claims, characterized in that the inlet and outlet directions of the intake and exhaust units are disposed parallel to each other. SUMMARY The invention relates to a retraction method for producing solid, transportable, printable bundles, in particular, bundles of bottles with a height / weight ratio of > 1 and containing substances with heat-sensitive content. The method of retraction comprises the steps of covering the bundles by packing with a film in such a way that an overlap section is produced at the ends of the film on the floor surface, heating them by heat transfer or convection, thereby merging the free ends in the region of the overlap, and then finally heating the bundles in a retraction furnace, the tied being thus produced stabilized by the retraction method. The incoming hot air is first limited by area to the floor surface and the contour of the bundle is stabilized while the bundle is transported continuously during the stabilization. The hot air directed against the region of the floor of the bundle in a beam of discretely distributed gas jets is emitted and returned after a zone-limited heat transfer to the film. Additional hot gas is directed laterally on the bundle, transported continuously, at a blow speed laterally increased in order to complete the retraction process.