HK1160624A - Closing device for closing preferably bag-shaped packing units - Google Patents

Description

Closing device for closing packaging means, preferably in the form of bags

Technical Field

The invention relates to a closure device for closing packaging means, preferably of the bag type, by crimping them together, said means having regions of different thickness along the opening of the package to be closed, such as square-bottomed bags, in particular made of coated or uncoated paper, cardboard, plastic, film and/or woven material, said packaging means having at least one suitable sealing surface which is incorporated into or applied to said material so as to permanently bond abutting or opposing surfaces and press against said material, wherein said closure device has a press head having at least one pressing means and at least one counter-pressure means between which said packaging means can be pressed in the region of the sealing surface of said packaging means by applying thermal energy as required.

Background

In the packaging industry, automated processing lines are used for filling and subsequent sealing of various packaging appliances, wherein the packaging appliances can be supplied to the processing line as pre-emptied containers, or the packaging material can be supplied to the processing line as a raw material (e.g. paper or cardboard, or film wound on a roll) and the packaging appliances can be made immediately before filling, for example by welding the rolled packaging material in the form of bags or by folding and gluing the paper sheets.

Bulk materials have special requirements for packaging appliances and packaging equipment, especially if they are to be packaged in the form of fine powders, as is often the case, for example, with building materials or other granular or powdery materials, for example in the pet goods industry. Furthermore, these materials must be packaged in very large quantities, usually using bags made of paper or cardboard (coated or uncoated), or (sometimes fibre-reinforced) plastics. Due to the high filling quantities and the resulting high weight, these bags are usually subjected to high stresses, but should not be too easily worn or broken even when the building floor is handled roughly.

Particularly high strength is obtained with square-bottomed bags which are not only very strong but, owing to their square shape, can be stacked and palletized, particularly in the filled state. Furthermore, the folded and still unfilled square-bottom pouches can be stacked well, so they are usually supplied in prefabricated form and transferred under the stack to the processing line, where they are then separated and unfolded, during which they are separated from the stack, opened and placed on a conveyor belt, usually by suction means, and transferred by the conveyor belt to the individual processing stations. Generally, these processing stations comprise:

-a filling assembly for placing the powder material in the pockets,

-a vibrator assembly for preventing the occurrence of bubbles in the powder material,

folding means pressing the bag openings together from both sides, in the course of which it must be ensured that the side walls of the square-bottomed bag are folded correctly inwards,

-a trimming device for trimming the upper edge of the bag,

sealing means for tightly sealing the opening of the bag, for example by hot-melt bonding, folding, sewing, crimping, and/or gluing, and

-a palletization device for stacking the filled and finished bags on pallets.

Although there are many packaging and sealing systems in use today, the current field of application can only achieve relatively low cycle rates, on the order of 10 to 20 packages per minute and per packaging line, and recent developments have only accelerated the processing speeds to a lesser and unsatisfactory degree. It is expected that the potential for improvement is great, particularly for conventionally used sealing devices.

In the case of square-bottomed bags, for example, the sealing surfaces are disposed inside the material layers of the bag in the region of the opening, and typically, these sealing surfaces comprise one or more layers of hot melt adhesive. For sealing, the bags are pressed together at their sealing zones and heated and bonded together in this way. To this end, the side walls of the previously filled bag are first folded inwards by a device and then the top of the bag is pressed together, for example by means of a shrinking rail. For the actual sealing process, the sealing area of the bag would then be placed between a press plate and a counter-pressure plate, and the plates would then be brought together to crimp the mouth of the bag between them. Depending on the material used for the sealing surfaces or the bag, either the pressure alone should be sufficient to seal the mouth of the bag by compression, or the sealing area may be heated by heating elements provided on the platen to achieve self-adhesion or to soften the hot melt adhesive applied to the sealing area. In order for the sealing surfaces on the inside of the package to be welded tightly, the pressure must be maintained for a sufficiently long time. Thus, the crimping time is related to the material to be sealed, the pressure applied to the material, and the temperature applied. The minimum required crimping time is critical to the cycle time achievable with this method, which at present is typically between 3 and 7 seconds and is empirically determined for each production run having a predetermined pressure. After crimping, the press plate is opened and the closed and sealed packaging appliance is transported by means of a conveyor belt to the next processing station.

In most cases, the process parameters required for tightly sealing the bag, in particular the temperature, pressure and pressing time, can only be determined empirically, as indicated above. The main reason for this is that manufacturers often do not disclose specific material characteristics of the supplied sealing materials, such as hot melt adhesives, and these characteristics sometimes differ from production lot to production lot. The packaging material may also vary with respect to its physical properties. It may therefore be necessary to adjust the parameters of the sealing device for the new conditions, even if the same product (e.g. a prefabricated square-bottomed bag) from the same manufacturer is still in process. Due to the fact that up to now, in currently commercially available sealing devices, sensors for measuring the actual pressure and the actual temperature in the sealing zone are not usually provided, making it more difficult to produce systematic methods for making these adjustments.

Another problem arises in packaging devices having different material thicknesses along the sealing zone. This is the case in square-bottomed bags, which in particular have four times the material thickness at the edges due to the inwardly folded side walls, and only twice the material thickness between the folded side walls. This may be the case in other packaging applications, for example because of the handle reinforcement or carrying handle to be embedded in the sealing area. Since it is not currently considered that layers of material having different thicknesses will be pressed together in a single process between two flat plates, the majority of the pressure will be applied to the thicker (e.g. four-layer) areas, while the thinner (e.g. two-layer) areas will often be pressed together only to an insufficient extent.

Because of these limitations, current sealing processes are rarely performed under optimal conditions, and poorly adjusted pressure and temperature parameters are typically compensated for by extending the crimping time, which in turn degrades the achievable cycle rate.

Disclosure of Invention

The object of the present invention is to produce a closure device for the above-mentioned packaging appliance, which is an improvement of the prior art with respect to process stability, processing speed, reliability and quality of the product processed by the sealing means. In particular, square-bottomed bags and other packaging means having different thicknesses along the package opening can be sealed uniformly and reliably using the closure device. Furthermore, by means of the device according to the invention, it is possible to react quickly and efficiently to changing material properties, in particular of the sealing surfaces.

Without limiting the invention, the packaging appliance may be made of, for example, paper, paperboard, plastic, film and/or woven material, although various other known materials may also be used in combination for the packaging appliance, such as laminates, co-extruded composites, metal and/or plastic coated materials, and the like. The term "layer" or "material layer" is also to be understood as including materials which themselves are composed of multiple layers of the same or different materials. In summary, the use of the present invention should not be limited to certain types of packaging devices, but should be able to be used with all packaging devices where the above-mentioned problems may arise.

According to the invention, these objects are achieved by a closure device of the type mentioned at the outset, the pressurizing means and counter-pressure means of which comprise regions of different pressure and/or different temperature along the package opening to be closed. These regions make it possible to apply over the entire closure region of the packaging appliance a pressure or temperature precisely adapted to the region to be applied in order to seal the sealing surface. Wherein the pressure or temperature in the individual zones can be adjusted substantially independently of one another, the required process stability can be reestablished relatively quickly and in a more targeted manner when the machine is being switched over to other packaging appliances, or even when the apparatus is adjusted for packaging appliances with varying characteristics.

In an advantageous embodiment of the invention, the pressure device can be designed as a movable pressure plate and the counter-pressure device as a movable or fixed counter-pressure plate, wherein the pressure plate and/or counter-pressure plate can have a plurality of, preferably three, zones with different, adjustable contact pressures and/or heat sources. This embodiment is suitable both for clock-controlled, automatically advancing packaging appliances in a processing line and for manual feeding in smaller versions. The sealing process corresponds essentially to the method used in the prior art, in which the packaging tool is crimped between a pressure plate and a counter-pressure plate and is heated, if applicable. However, due to the fact that both pressure and temperature can be adjusted separately in the individual zones, the three different zones can be used for sealing packages having zones of different thickness. On the press plate and the counter-press plate, they are designed in three parts to seal the square-bottomed bag, the two side areas corresponding to the four-layer side areas of the square-bottomed bag, and the area between the two side areas corresponding to the two-layer area.

A pressure plate or counter-pressure plate of this design can advantageously consist of a plurality of plates which are spring-loaded relative to one another. The individual spring loaded plates, each representing a zone, may be heated, for example, by separate heating coils. The pressure exerted by each plate can be adjusted by means of a spring and adapted to the requirements applicable. The individual spring-loaded plates correspond to the thickness of the bag in the applicable areas, while the working pressure in each area can be precisely adjusted and adapted to the applicable conditions by adjusting the spring pressure. The temperature of the individual zones can also be adjusted individually. Thus, for example, sealing four layers would require higher pressures and temperatures than would be required to seal only two layers. For this reason, the device of the invention can be used both for bags in which the sealing surfaces are bonded together predominantly by heat (e.g. hot-melt adhesive sealing) and only require a low pressure, and for sealing surfaces in which the sealing is bonded predominantly by a strong pressure (or by the heat arising in the process) and thus requires very high pressure and little or no heat.

A similar effect can be achieved by a further advantageous closing device, the pressure plate and counter-pressure plate of which are designed as flexible plates with different pressure zones. In this design, the different pressure zones are not formed by different spring elements, but by the elasticity of the plate itself. The surface of the elastic plate extends over the entire pressure area, so that folding lines of the packaging material, which might occur in the vicinity of the joints when using a group of press plates, are avoided.

In order to make the packaging appliance continuously pushable, in a further advantageous embodiment of the invention the pressure means and the counter-pressure means can be designed as press rollers which bear elastically in tension against one another and can be heated, said press rollers having a smooth or profiled (profiled) circumferential surface. By a suitable choice of the spring, which presses the pressure device and the counter-pressure device against one another, different pressure zones can be created. As mentioned above, the areas of the package requiring different pressures (e.g. the inwardly folded side walls in a square-bottom bag) have different thicknesses (four layers in the side fold region and two layers between the side fold regions in the case of a square-bottom bag). In this case, higher pressures are generally required to seal the package in thicker regions with more material layers than in thinner regions. Since the thickness difference is usually only 1 to 2mm or less, a pressure spring has to be selected for the roller, and due to the elastic properties of the spring, even small changes in the spring deflection produce suitable pressure variations. The relationship between the preload of the spring and the difference in contact pressure between areas of thick and thin material can be influenced by selecting a spring with suitable spring characteristics (e.g. linear characteristics: varying preload but equal distance; progressive characteristics: increasing difference with increasing preload; decreasing characteristics: decreasing difference with increasing preload; or discontinuous characteristics). To allow more complex adjustment, the different pressure adjustments can also be controlled by a linkage mechanism that is adapted to the passing packaging appliance.

In addition to the press roll having a smooth surface to create a smooth surface on the packaging appliance at the processing zone, the press roll according to the invention may instead have a profiled circumferential surface, such as one or more longitudinal, transverse or oblique corrugations. These creases not only affect the appearance of the packaging device, but also have a beneficial effect on the bond strength achievable by the seal. The folds on the opposed press and counter-press rolls may also be arranged so that they are offset from each other, so that the pressure that is generated between the side edges of the opposed tips can be considerably higher than that which can be generated between the smooth press rolls, if the tips of the folds are large enough and the packaging appliance is a correspondingly thin-walled material.

A further advantageous embodiment of the closing apparatus according to the invention defines that, at least in the region of the pressure means, the packaging tools are held such that the height of their sealing surface between the conveyor belts passes between the pressure means and the counter-pressure means, wherein one or more rollers can be provided for supporting the conveyor belts. The belt guide not only ensures correct positioning of the packaging appliance being processed (for example in the case of clocked advancement), but also provides spatial separation of the packaging appliance and the pressure or counter-pressure device, whereby the pressure or counter-pressure device can be protected from contamination when the packaging appliance is filled with fine powder or dust-generating bulk material. In the case of a pressure device embodied as a pressure roller, the use of a belt guide allows for higher production speeds. With only one pair of opposing pressure rollers, the packaging tool can be transported only relatively slowly, since a sufficiently long crimping (heating) time is ensured for the sealing surfaces. If a plurality of pairs of press rollers are arranged in a row, it is difficult to maintain the contact pressure sufficiently stably without a belt guide because no pressure can be applied between each pair of press rollers. The belt guide makes it possible to arrange an almost unlimited number of pairs of press rollers in a row, while the packaging appliance passes between and is pressed by them. The pressure difference between the pair of pressure rollers can also be reduced by the additional rigidity of the belt. The time of the crimping process is no longer limited primarily by the advancing speed of the packaging appliance, but by the length of the conveyor belt and the number of (press) roller pairs arranged thereon. This allows the processing speed and thus the throughput to be significantly increased.

In order to minimize heat losses, in another embodiment the conveyor belt may comprise inductively heatable metal elements, wherein one or more induction coils may be arranged in the vicinity of the pressure means in order to heat said conveyor belt. The induction coils may be placed inside the pressure plate or counter-pressure plate so that the packaging appliance is heated simultaneously when it is crimped, but they may also be arranged before or after the pressure device. Since the pressing means is constituted by one or more pairs of press rolls, said induction coil can be arranged before, between or after the press rolls. In all cases, the heat energy can be generated precisely where required for the sealing process, i.e. directly on the packaging appliance. Due to the simple, intermittent circulation of the induction coil, it is also possible to heat the conveyor belt only where the packaging appliance is actually held, and not in the free space between them.

In a further embodiment, a suction attachment connected to the suction device and adapted to generate a negative pressure in the packaging appliance can be arranged directly before or integrated in the pressure device. In particular, powdered bulk materials tend to trap air bubbles when placed in a packaging device. By using a vibrator assembly, trapped air can often be removed during or after filling, although it is not possible to fill the packaging appliance completely (i.e. to reach the bottom edge of the sealing surface) and free space must always be left between the bulk material and the bottom edge of the sealing area. This safety gap results in air being easily trapped between the bulk material and the sealing area during sealing of the packaging appliance, and said air may cause the packaging appliance to break open during stacking and handling of the packaging appliance. By means of a suction fitting, for example, arranged above the still open bag before the sealing device, excess air can be drawn off immediately before sealing, so that the tightness of the filled and sealed packaging unit is ensured, in order to substantially prevent breakage of said packaging unit during stacking, palletizing or handling. In addition to the suction fitting located above the seal of the bag, a flat-head nozzle can be used, which is inserted into the opened bag in order to evacuate the air and spill it out of the package before the sealing process. The suction capacity of the fitting should not be too strong to allow the filling material to be sucked out, but in many cases it should be sufficient to prevent the formation of air bubbles.

In a further embodiment of the invention, pressure and/or temperature sensors can advantageously be arranged on the pressure device and/or the counter-pressure device. The sensors facilitate systematic acquisition and optimization of system parameters when setting up and adjusting the system, and can be used for in-process quality control during an ongoing operational process.

In another embodiment, the processing and production time can be further reduced by providing the closing apparatus with a cooling device located after the pressure device, wherein the cooling apparatus can have one or more cooling plates, one or more cooling rolls or belts, and/or one or more cooling blowers. The cooling device can accelerate the solidification of the seal, especially at high processing temperatures.

Furthermore, the closure device can additionally have a punch for introducing a handle opening in the packaging appliance. In this case, the handle opening can be introduced into the aforementioned sealing region, preferably after cooling. In this case, a sealing region with increased stability is used, since the handle opening can support larger load-bearing loads without tearing than in the case of an unsealed material.

In particular, in one embodiment of the invention, the punch may be incorporated into the cooling device when the cooling device comprises two cooling plates that compact the sealing area from both sides for cooling. This allows a particularly compact construction and a shorter processing line.

In another advantageous embodiment, the punch may have one or more cutting edges, at least one of which is discontinuous against the top of the packaging appliance. The handle opening punched out with the cutting edge is folded back at discrete locations when being gripped, so that double the material thickness occurs in the region gripped by the hand (gripping area), thereby increasing the stability of the gripping area. This avoids the formation of cuts at sharp cutting edges, since the fingers holding the handle opening carrying the grip are only in the folded position, the comfort of the grip is improved by the improved pressure distribution, since the grip is not pressed sharply into the hand.

In another embodiment of the invention, the closing device may have means for trimming the rim of the top container, said means being preferably located in front of said pressure means; the device may be provided with suction means, if desired. The top edge of the packaging appliance is preferably trimmed after the packaging appliance has been filled and subsequently folded together and before being transferred to the pressing device. The dust generated during trimming and the edges that have been cut off are discharged by means of a suction device. This has the advantage that any dirt that may be present outside the bag during filling, and not only the material produced during cutting, can be discharged by the suction device. Furthermore, some of the air in the bag is likewise removed by means of the suction device, so that in some cases the suction fitting described above for generating the negative pressure can be omitted, since its function can be fulfilled by the suction device of the finishing device.

In another embodiment according to the invention, a hot melt adhesive can be applied to the sealing surface of the packaging appliance. While the device of the present invention can be used with a variety of different sealing surfaces, the hot melt adhesive surface can provide good processing characteristics and allow for a high degree of sealing force.

Drawings

The invention will now be described in detail using exemplary embodiments and with reference to the accompanying drawings. The drawings show:

FIG. 1 is a top view of a converting line in which a closure apparatus according to the present invention is used;

FIG. 2 is a front view of a central area of a converting line having a folding device, a trimming device, and a sealing/pressure device;

FIG. 3 is a forward section of the converting line from the bag supply to the inlet of the sealing device;

FIG. 4 is a schematic view of the area of the converting line containing the sealing device, viewed from below;

FIG. 5 is a schematic view of a folding device for folding together the openings of filled packages;

FIG. 6 is a front view of the heat seal/press apparatus;

FIG. 7 is a cross-sectional view along line VII-VII of FIG. 6 through the platen of the pressure device, in which the spring mounts of the platen of the individual pressure zones are visible;

FIG. 7a is a cross-sectional view along line VII-VII of another embodiment of a platen of the pressure device of FIG. 6, wherein the platen is made of an elastomeric material and has a contoured surface;

FIG. 8 is a side view of the pressure device;

FIG. 9 is a schematic view of the platen of the press apparatus with different heating zones visible;

FIG. 10 is a top view of a cooling device having an integrated punch for introducing a handle opening into a sealed bag;

FIG. 11 is a side view of an apparatus including a cooling device and a punch;

FIG. 12 is a schematic view of another embodiment of a press apparatus having a spring loaded press roll, two conveyor belts, and an induction coil for heating the conveyor belts;

FIG. 13 is a schematic view of a spring loaded nip roller pair having a convoluted periphery to create a contoured sealing surface;

FIG. 14 is a cross-sectional view of an alternative embodiment of a pressure roller;

FIG. 15 is a cross-sectional view of the nip roll taken along line XV-XV of FIG. 14;

FIG. 16 is a schematic view of a spring loaded platen pair having a profiled circumferential surface to create longitudinal grooves;

FIG. 17 is a side view of the pressure roller of FIG. 16;

fig. 18 is a side view of another press roll provided with a honeycomb profile.

Figure 19 shows a top view of a press with spring loaded compression rollers and details of the package between the compression rollers.

Detailed Description

Fig. 1 shows a top view of a processing line with a closing apparatus 1 according to the invention, in which the individual processing stations are schematically shown. Fig. 1 can be used to illustrate the individual process steps necessary for filling, closing, stacking packaging utensils 2, in particular square-bottomed bags, wherein the device embodying the invention will be shown in more detail in the other figures.

The packaging tools 2, in this case square-bottomed bags, are transferred to the system by means of a bag supply 23, wherein the bags can be placed in the supply by hand or can be supplied in boxes and can be converted into individual packaging tools as required. The square-bottom bags are folded and stacked, taken out from the bag supply device 23 by the carrying and unfolding device 26, unfolded and placed on the conveyor belt 21. The conveyor belt 21 can convey the packaging tools 2 in a continuous or endless manner, wherein transitions between continuous and endless conveyance can also be provided between the individual processing stations. The opened bag is then transferred to the filling assembly 22, which filling assembly 22 and the handling and deployment device 26 are shown in more detail in fig. 3.

As is evident from fig. 3, the conveyor belt 21 is arranged in the region of the filling assembly 22 with a support plate 28, which supports the lower region of the side of the packaging appliance 2. The support plate 28 is only schematically shown in fig. 3 and is preferably movable together with the packaging appliance, as will be readily apparent to a person skilled in the art. Said support plate is mainly intended to increase the stability of the packaging appliance 2 during filling. The filling assembly 22 dispenses an appropriate amount of material to be filled into each package 2, during which process air bubbles may form in the bag, especially in the case of dust-generating fine material. In order to prevent the formation of said bubbles and the crimping of the material in the package, the packaging appliance 2 can be shaken near or after the filling assembly 22 by means of a vibrating support plate 28, or by means of a vibrator device (not shown) located below the conveyor belt 21. The filled packaging appliance 2 is then transported to other processing stations by means of a conveyor belt 21. To increase productivity, the filled packages may, if desired, be distributed via changeover switches 29 to a plurality of converting lines, as indicated by an optional converting line 30 shown in broken lines. In addition, even in the presence of an alternative converting line, all packaging appliances 2 can pass through the same converting line, so that the alternative converting line 30 can be serviced or switched.

Arranged in the upper part of the packaging appliance 2, inside the bag, are sealing surfaces 4 which can be sealed together by pressing, if applicable under the influence of heat. The sealing surface 4 may comprise a layer of hot melt adhesive coated on the packaging material. In addition, the packaging material itself can be sealed by the action of heat and pressure. The sealing surface 4 may be provided in an upper portion of the package, i.e. the sealing or closing portion, or it may extend over the entire surface of the package, if this is advantageous from a production point of view. The sealing surface 4 is preferably arranged on the inside of the packaging means 2 in the closing position and can be arranged on the outside of the packaging means 2 in the region of the side wall 32. While no additional outer sealing surface is required on the side wall 32 to seal the package opening, it may still be desirable for aesthetic reasons or for reasons of stability of the finished package.

As is again evident from fig. 1, in order to seal the packaging appliance 2 tightly, said appliance then reaches the folding device 25, the trimming device 11 provided with suction means, the sealing/pressing device 10 and the cooling device 8 provided with the punch 9. This part of the processing line contains the necessary improvements according to the invention, which is only shown in outline in fig. 1, since the detailed embodiments will be described more in depth in connection with the other figures. Once the packaging tools 2 have passed through this part of the processing line, they are sealed and provided with a punched-out handle opening 37 and are finally conveyed by the conveyor belt 21 to the palletization device 24, where they are stacked on pallets by known techniques. Before stacking, the upper edge of the sealed packaging appliance can be worked once more, for example by another trimming with a trimming blade 31, as shown in fig. 2.

The device used for sealing the packaging appliance 2 is shown in front view in fig. 2 and again in a diagrammatic manner in fig. 4, seen from the below. The filled packaging appliance first reaches the folding device 25. This arrangement ensures that all closing points of the packaging appliance 2 which arrive in the correct orientation at the subsequent guide plate 27 are folded correctly. As shown in more detail in fig. 5, the folding device 25 mainly comprises four bag spreaders 33 and two side panels 34. The folding device 25 with the bag extenders 33 and the side panels 34 is lowered onto the filled packaging unit 2 from above so that the four bag extenders 33 are located inside the packaging unit 2 and the side panels 34 are located outside the packaging unit 2 adjacent to the side walls 32. Bag spreader 33 is then moved slightly outwardly to hold the corners of packaging appliance 2 in place, while side panels 34 press side walls 32 inwardly into the bag so that the fold in the center of the side walls at the upper portion of the packaging appliance extends into the interior of the bag. Thereafter, the folding device 25 pulls the packaging appliance 2 upwards again. The packaging appliance 2 is then moved forward by the conveyor belt 21, wherein said closing points, now oriented for correct folding, reach between the two guide plates 27, converging together with said closing points with the inwardly folded side walls 32 in between. In the process, the sealing surfaces 4 on the inside of the packaging appliance 2 and, if applicable, the side walls 32 arranged on the outside of the packaging appliance 2 also converge towards one another.

As is evident from fig. 2, the means 11 for trimming the top edge of the packaging appliance 2 are arranged directly behind the guide plate 27. The cut strip of material is withdrawn by suction means 20. The suction device 20 also serves to draw away material residues that have stuck to the package during filling. Furthermore, material residues and dirt that accumulate on the sealing surface 4 inside the packaging appliance 2 can also be removed by the suction device 20, thereby increasing the reliability of the sealing. Since the suction nozzle of the suction device 20 is applied directly to the opening of the already closed, but not yet sealed packaging appliance 2, excess air can be sucked out through the opening gap of the packaging appliance 2 before the packaging appliance 2 is sealed. After sealing, the air remaining in the package may have the consequence that the "inflated" packaging devices 2 burst when stacked. The suction device 20 can provide a more compact container in which the suction force can be adjusted so that the suction nozzle will only suck out air remaining in the packaging appliance 2, not the filling material.

The actual sealing process takes place by means of a pressure device 5 and a counter-pressure device 6 which press against the sealing site of the packaging appliance, preferably under heat, wherein the design of the pressure device 5 and the counter-pressure device 6 represents a key feature of the invention. In a preferred embodiment, the pressurizing means 5 and the counter-pressure means 6 are designed as pressure means 10, which will be described in more detail below with reference to fig. 2, 4 and 6 to 9.

As is particularly evident from fig. 4 and 8, the pressure device 10, as is also the case in the known sealing devices of the prior art, comprises a pincer-like device with a pressure plate 13 and a counter-pressure plate 14 between which the area to be sealed is crimped. Heating elements for heating the sealing surface 4 can be arranged in the pressure plates 13, 14 (or in the jaws located behind them). In contrast to conventional sealing arrangements, in which the pressure plate and counter-pressure plate are designed as substantially flat, uniform heating plates, in the shown sealing arrangement according to the invention the pressure plate 13 and counter-pressure plate 14 each have three pressure zones 7, 7', 7 ", the method of operation of which will be described with reference to fig. 6 and 7.

Fig. 6 shows a pressure device 10 according to the invention, in which a packaging appliance 2 can be clamped between the jaws of the pressure device 10 for sealing. As is clear from the above, the sealing zone of each packaging unit 2 has at least three regions of different thickness, caused by the inwardly folded side panels 32: at the side edges, the side panels 32 are folded inwards between the two sides of the package 2, so that the package 2 has four layers, and only two layers in the centre of the sealing area of the package 2. This is clearly visible, for example, in the cross-sectional view of fig. 7, as in the sealing area of the packaging appliance 2 clamped between the press plate 13 and the counter-pressure plate 14. The pressure device 10 according to the invention takes this fact into account by means of three pressure zones 7, 7', 7 ", whereas the pressure or temperature of said pressure zones can be adjusted independently of each other.

In conventional press devices, in which the packaging means are crimped in two flat plates, it is not possible to select the contact pressure and temperature to produce an optimum contact pressure for each sealing surface 4 to be sealed, since the thicker edge regions (7, 7 ") are always crimped more than the central region (7'). In addition, thinner layers of material heat up more rapidly than thicker layers. Until now, compromises have always been found for the adjustable parameters (pressure, temperature, crimping time), with the crimping time generally increasing and the production time increasing in the case of non-optimized settings.

In the press device shown in fig. 7, the contact pressure in all pressure zones 7, 7', 7 "can be adjusted individually for the packaging appliance 2 to be processed by means of separate adjusting springs 35, so that the correct parameters can be found and set for each zone. In a preferred embodiment, the prevailing pressure and temperature conditions of the individual pressure zones 7, 7', 7 "can be measured directly on the packaging appliance by means of suitable sensors, so that the recorded measured values can be used to determine empirically the optimum setting based on a systematic procedural method of the conditions actually present. Using parameters measured by separate sensors, rather than parameters derived from set points, the results obtained directly can be compared to measured values and settings measured and recorded by similar machines.

The values measured in the individual pressure zones 7, 7', 7 "make it possible for the first time to relate the processing parameters directly to the applicable material properties. The material properties thereof are, in particular, the paper thickness, the number of paper layers in the applicable area, the characteristics of the sealing material used (for example, the particular brand of hot-melt adhesive) and the number of sealing surfaces 4 to be sealed in the area. Depending on whether sealing surfaces are additionally provided on the side plates 32 (and the bag opening), two or three pairs of surfaces to be sealed can be present on the pressure zones 7, 7 "on both sides, for example even when crimping the same number of sheets in both cases. All these parameters can be collected and recorded, for example centrally by the manufacturer of the packaging appliance or sealing device 1, and can be made available in ready form to the customer using the device according to the invention.

A systematic programming of this nature makes it possible to use settings which are already very close to the optimum settings, even before the first running test on the newly set-up machine (or after the machine has been changed for a new packaging appliance). This not only shortens the production time, but also reduces the amount of waste products generated during system adjustment. Furthermore, the pressure and temperature parameters that can be optimized for each pressure zone 7, 7', 7 ″ make it possible to reduce the third parameter, i.e. the crimping time. Thus, cycle time can be reduced, thereby improving throughput.

The embodiment of figure 7 with three, respectively spring-loaded pressure and counter pressure plates 13, 14 allows very precise adjustment of the individual pressure zones 7, 7', 7 ", although in some cases it may be advantageous to realize different pressure zones in a flexible pressure or counter pressure plate, as shown for example in figure 7 a. The contact pressure in this design is dependent on the different material thicknesses of the elastic sheet material in the respective areas. In combination with the different material thicknesses, it is also possible to generate a specific contact pressure for each pressure zone 7, 7', 7 "which depends on the overall contact pressure. With this design, a systematic change to a different packaging appliance can be achieved simply by exchanging the pressure plate 13 and the counter-pressure plate 14. Thus, although this embodiment has less opportunity for adjustment than the multi-part embodiment of fig. 7, it offers a wide variety of forms, so that the device can also be adapted to, for example, different sizes of pressure zones 7, 7', 7 ", for example caused by different widths of side panels 32 of packaging 2 of different thicknesses. The transition of the individual pressure zones 7, 7', 7 "in this embodiment can also be provided with a gradual transition in order to avoid that bulges are pressed into the material, which might lead to material fracture.

Although the herein described press head of the closing device 1 according to the invention has three pressure zones 7, 7', 7 ", the invention can also be used for packaging appliances 2 having more than 3 different pressure zones. For example, if the packaging appliance 2 has a seam, an additional pressure area may be required, so that for example a short segment with four layers will be present in the two-layer material area. Furthermore, material reinforcements for carrying handles can be provided in the sealing region of the packaging appliance, which likewise leads to a greater material thickness in limited regions. The embodiment shown in fig. 7a, in particular with a flexibly designed pressure plate, is particularly suitable for this kind of more demanding shapes.

Fig. 8 shows the pressure device 10 with the schematically shown packaging appliance 2 located thereunder in a side view. Shown above the packaging means 2 is a suction attachment 12 connected to a suction device, by means of which air can be drawn directly out of the packaging means before sealing. The suction fitting 12 may be provided in addition to or alternatively to the suction device 20 shown in fig. 2.

Fig. 9 shows a schematic view of the press plate 13 and the counter-press plate 14 of the press, wherein suitable heating elements 36, 36 ', 36 "can be provided in each individual press zone 7, 7', 7", by means of which the temperature in the individual zones can be set independently of one another. The heating elements 36, 36', 36 ″ can be arranged directly in the pressure plate 13 or counter-pressure plate 14 or in the jaws of the pressure device 10 located behind them.

In a further embodiment of the invention, the pressure means 5 and the counter-pressure means 6 for sealing the packaging appliance 2 are designed as pressure rollers 17 which bear elastically in tension against one another and can be heated, which have a smooth or profiled circumferential surface and are preloaded against one another by means of elastic pressure springs 43. For sealing, the sealing area of the packaging appliance 2 will pass between the pressure rollers 17 which are preloaded against each other. Fig. 19 schematically shows an operation method of such a platen roller 17. Fig. 19 shows a top view of two pairs of pressure rollers 17, 17' between which the packaging appliance 2 passes. The pressure roller 17 acting on the wider part of the packaging appliance due to the folded side panel 32 will be further apart because the material thickness is greater there than at the pressure roller 17' acting on the narrower part. Thus, the contact pressure (F) is determined₁，F₂) Spring bias (Z)₁，Z₂) It will also exhibit a difference (az) which varies with the position of the rollers 17, 17' and which corresponds to the thickness of the material situated between the rollers.

Since the material layers have different thicknesses, different pressure zones result, wherein a thicker material layer generates a higher spring force. Since this thickness difference is typically only 1 to 2mm or less, such a pressure spring 43, 43 'has to be selected for the pressure roller 17, 17': due to their spring characteristics, an appropriate pressure change can be generated even for small variations Δ z in the spring deflection. The relationship between the preload of the pressure springs 43, 43' and the difference in contact pressure between the regions of thick and thin material can be influenced by selecting springs with suitable spring characteristics (for example linear characteristics: varying preload but equal distance; progressive characteristics: increasing difference with increasing preload; decreasing characteristics: decreasing difference with increasing preload; or discontinuous characteristics).

To allow more complex adjustment, the different pressure adjustments can also be controlled by a linkage mechanism that is adapted to the passing packaging tools 2. The pressing time can be adjusted by the speed of the packaging appliance 2 or the rotational speed of the pressure rollers 17, 17'.

As an example of a press roll with a profiled surface, fig. 13 schematically shows a press roll pair 17a with a circumferential surface that is corrugated in order to create a profiled packaging surface in the sealing zone. As shown in fig. 14, the bottom area of the press roll 17 a' may be conically tapered in order to prevent the formation of an excessively sharp package-pierceable transition at the bottom edge of the processing surface. FIG. 15 is a cross-sectional view taken along line XV-XV of FIG. 14, in which it can be seen that there are different wrinkle depths in the top and bottom roll regions.

Fig. 16 shows an additional pair of press rolls 17b having a profiled periphery to create longitudinal grooves. The rollers may also be designed with a tapered bottom area to avoid fold lines, as shown by roller 17 b' in fig. 17.

The press roll 17c shown in fig. 18, which has a honeycomb-shaped surface design, is another example of a profiled circumferential surface.

Fig. 12 shows another advantageous embodiment of the invention. In the vicinity of the pressure means 10 in this design, the packaging tools 2 are held at the level of their sealing surfaces 4 between conveyor belts 18, which pass between the pressure means 5 and counter-pressure means 6. The pressure means 5 and counter-pressure means 6 are realized as pairs of press rolls 17, which are located after the conveyor belt and which are mutually preloaded against each other by means of pressure springs 43. The mode of operation is similar to that described in connection with fig. 19, and the contact pressure of the pressure rollers of each pair can be distributed over a wider range because of the conveyor belt 18 than in the case of pressure rollers acting directly on the packaging material.

In order to heat the sealing surfaces 4 pressed against each other between the conveyor belts 18 by the press rollers 17, induction coils 19 can be arranged before, after or between the press roller pairs, while the conveyor belts 18 can contain inductively heated metal elements. Since the conveyor belt 18 can be heated in a well-defined area by means of the induction coil 19, it is possible to heat the passing packaging tools 2 in an accurately targeted manner. Due to the intermittently switchable induction coil 19 can be switched off in the free space between the two packaging tools 2, so that the conveyor belt 18 is heated only in the region which is also used to hold the packaging tools in the middle.

Once the opening of the packaging appliance 2 has been sealed by the pressure device 10, said packaging appliance is conveyed by means of the conveyor belt 21 to the cooling device 8, which is provided with a punch 9 for introduction into the handle opening 37. FIG. 10 shows a top view and FIG. 11 shows a side view of an exemplary cooling device 8. The sealed region of the packaging tool 2 is fed into the guide groove 40 for punching, wherein the blade of the punch 9 laterally punches the handle opening 37 in the sealed region. The punch is located on a punch support 41 which is movable on two guide rods 38 perpendicular to the guide grooves 40 by means of a preferably hydraulic, pneumatic or electromagnetic drive, which is not shown for the sake of clarity. After punching, the punch holder 41 is returned to its initial position by two return springs 42. In order to cool the sealing surface 4 after pressing and heating in order to facilitate curing, a cooler for the sealing site of the packaging appliance can be arranged in the vicinity of the channel 40. For this purpose, a cooling plate 15 can be provided, which can be placed or pressed onto the packaging from the outside at the sealing location, whereby heat can be removed from the sealing location of the packaging, for example by means of a heat sink 39.

The cutting edge 16 of the punch 9 may preferably be discontinuous against the top of the packaging appliance 2, as shown by the handle opening 37 in fig. 2. In order to grip the packaging device 2 at the handle opening 37 created for this purpose, the punched-out area can be folded back at discrete positions, so that double the material thickness occurs at the area for gripping by hand (gripping area), which increases the stability of the gripping area. Since the fingers of the hand being held only hold the handle opening 37 in the folded position, cuts on sharp cut edges can be avoided and the comfort of carrying can be increased by an improved pressure distribution, since the grip cannot be pressed sharply into the hand.

In a further variant embodiment, not shown, the activation of the adhesive can be achieved by means of an ultrasonic or microwave generator. For this reason, the closure device may thus be placed in a radiation-shielding container, so as not to endanger the operator. The crimping may then be accomplished by a compression roller or platen.

Claims (17)

1. A closure device for closing a preferably bag-shaped packaging means (2) by crimping, which packaging means comprises regions of different thickness along the packaging opening to be closed, such as square-bottomed bags, in particular packaging means made of coated or uncoated paper, cardboard, plastic, film and/or woven material, which packaging means (2) has at least one suitable sealing surface (4) which is incorporated into or applied to the material in order to permanently bond adjoining or opposing surfaces and press against the material, wherein the closure device (1) has a pressure device (10) with at least one pressure device (5) and at least one counter-pressure device (6) between which the packaging means (2) can be crimped in the region of the sealing surface (4) of the packaging means (2), preferably by applying thermal energy, the method is characterized in that: the pressurizing means (5) and the counter-pressure means (6) comprise areas with different pressures and/or different temperatures along the package opening to be closed.

2. The closure device of claim 1, wherein: the pressure device (5) is designed as a movable pressure plate (13) and the counter-pressure device (6) is designed as a movable or fixed counter-pressure plate (14), wherein the pressure plate (13) and/or the counter-pressure plate (14) has a plurality of, and preferably three, regions (7, 7') with different, adjustable contact pressures and/or heat sources.

3. The closure device of claim 2, wherein: the pressure plate (13) or counter-pressure plate (14) consists of a plurality of plates which are spring-loaded relative to one another.

4. The closure device of claim 2, wherein: the pressure plate (13) or counter-pressure plate (14) is designed as a flexible plate with different pressure zones.

5. The closure device of claim 1, wherein: the pressing device (5) and the counter-pressure device (6) are designed as press rolls (17) which are elastically tensioned against one another and can be heated, said press rolls having a smooth or profiled circumferential surface.

6. The closure device of claim 5, wherein: the press roll (17) has a profiled circumferential surface, such as one or more longitudinal, transverse or oblique corrugations.

7. The closure device according to one of the preceding claims, characterized in that: at least in the region of the pressure device (10), the packaging tools (2) are held such that their sealing surfaces (4) pass between the conveyor belts (18) at the level of their sealing surfaces, which pass between the pressure device (5) and the counter-pressure device (6), wherein one or more rollers can be provided for supporting the conveyor belts.

8. The closure device of claim 7, wherein: the conveyor belt (18) contains inductively heatable metal elements, and wherein one or more induction coils (19) are arranged in the region of the pressure device (10) in order to heat the conveyor belt (18).

9. The closure device according to one of the preceding claims, characterized in that: a suction fitting (12) connected to the suction device and suitable for generating a negative pressure in the packaging means (2) is arranged directly before or integrated in the pressure device (10).

10. The closure device according to one of the preceding claims, characterized in that: a pressure and/or temperature sensor is arranged on the pressure device (5) and/or the counter-pressure device (6).

11. The closure device according to one of the preceding claims, characterized in that: the closing device (1) additionally has a cooling device (8) located downstream of the pressure device (10), wherein the cooling device can have one or more cooling plates (15), one or more cooling rollers or belts, and/or one or more cooling fans, if applicable.

12. The closure device according to one of the preceding claims, characterized in that: the closing device (1) additionally has a punch (9) for introducing a handle opening (37) in the packaging appliance (2).

13. The closure device according to claims 11 and 12, wherein: the punch (9) (9) is integrated into the cooling device (8).

14. The closure device according to claim 12 or 13, wherein: the punch (9) has one or more cutting edges (16), at least one of which is discontinuous against the top of the packaging appliance (2).

15. The closure device according to one of the preceding claims, characterized in that: the closure device (1) has a trimming device (11) for trimming the rim of the top container, said device (11) being preferably located in front of said pressure device (10), said device (11) being provided with suction means (20) if necessary.

16. The closure device according to one of the preceding claims, characterized in that: the sealing surface (4) of the packaging tool (2) is provided with a hot melt adhesive.

17. The closure device of claim 1, wherein: an ultrasonic or microwave generator is associated with said pressure means in order to activate the adhesive force.