EP3519311A1

EP3519311A1 - Plastic bag, in particular ffs bag, and method and device for producing and filling a bag

Info

Publication number: EP3519311A1
Application number: EP17772072.9A
Authority: EP
Inventors: Thomas Hawighorst
Original assignee: Windmoeller and Hoelscher KG
Current assignee: Windmoeller and Hoelscher KG
Priority date: 2016-09-27
Filing date: 2017-09-27
Publication date: 2019-08-07
Also published as: US20200122894A1; WO2018060277A1; CN109996736A

Abstract

The invention relates to a plastic bag, in particular an FFS bag, comprising a first wall and a second wall, which are joined to each other by means of side edges or side folds and by means of bottoms and which bound a bag interior, wherein at least one bottom comprises a weld seam, which extends between the side edges and touches the side edges, and venting openings in the first and/or in the second wall for venting the bag interior, characterized in that at least one channel is provided on the outside of at least one wall, which channel covers the venting openings and is formed at least by two parallel fastening strips and by a cover strip, wherein the cover strip likewise comprises venting openings and wherein the shortest path between the parallel fastening strips along the cover strip is longer than the shortest path along the at least one wall between the parallel fastening strips or the cover strip and/or the parallel fastening strips consist of stretchable material.

Description

Plastic bag, in particular FFS bag, and method and apparatus for producing and filling a bag

The invention relates to a plastic bag according to the preamble of claim 1 and a method according to the preamble of claim 9 and a device according to the preamble of claim 12.

FFS sacks are those sacks that are usually produced within a device initially from a tubular web, then filled and finally closed. FFS sacks are sacks that are filled with a product weighing at least 5 kg (filling weight). Sacks with a filling weight of at least 25 kg are even the rule. The tubular web used is often, but not exclusively, provided with Seitenfatten. The bags made therefrom therefore have a first wall and a second wall, which are interconnected by side edges or gussets as well as by floors. As a result, a bag interior is limited. It is understood that in the case of existing gussets these are also connected by side edges with the walls.

When filling this - at this time already provided with a bottom - bags there is the problem that the registered with the contents in the interior air must escape, so as to keep the volume of the bag filled as small as possible. Air left in the bag can also cause it to burst easily if it accidentally hits the ground from a certain height. In addition, can the stackability of these bags be reduced. Conventional sacks are therefore provided with vents, which may include, for example microperforations, so that although air, but no filling material can escape. WO 2007/087965 discloses two longitudinally and fluidly connected channels which constitute a labyrinth vent. Here, the vents can be made comparatively large. Nevertheless, in known sacks often the necessary ventilation performance is not sufficient, because in recent years, the filling performance of the generic FFS systems for sacks with more than 5 kg filling weight has risen steadily.

The object of the present invention is therefore to propose bags with a higher venting performance as well as a method and an apparatus for producing and filling these bags.

According to the invention, the object is achieved by all the features of claim 1.

Thereafter, in a plastic bag, in particular an FFS bag, comprising a first wall and a second wall which are joined together by side edges or gussets and bottoms and define a sack interior, at least one bottom comprising a weld seam extending between the side edges runs and this touches, and comprising vents in the first and / or in the second wall for venting the sack interior, according to the invention provided that at least one channel is provided on the outside of at least one channel which covers the vents and which at least by two parallel attachment strips and an overlay strip, the overlay strip also including vent openings, and wherein the shortest path between the parallel attachment strips along the overlay strip is longer than the shortest path along the at least one wall consist of the parallel attachment strip or the cover strip and / or the parallel attachment strips of stretchable material. The sack interior facing sides or surfaces of the first wall and the second wall can also be referred to as inner sides, the sides facing away from the bag interior can be correspondingly referred to as outer sides. Such a bag has an extension direction that goes in the direction of the largest longitudinal axis, which is parallel to the outer edges. As already mentioned, the first and second walls are connected to one another by two edges and can be formed in one piece. The walls may be formed from a circumferential circumferential to the tube or be formed to form a tube to form a longitudinal overlap region of a flat track. In such a hose gussets can be inserted, in which case the first wall is connected by a respective outer edge, each having a first position of the gusset and the second wall is connected by a respective outer edge, each with a second position of the gusset. Depending on a first position of the gusset is connected to a respective second position of the gusset by an inner edge. The outer edges and inner edges advantageously run parallel to the extension direction of the tube or of the later bag. The width of a gusset layer defines the so-called gusset depth.

The at least one cover strip is fastened with at least two fastening strips which are fastened parallel to the extension direction on an outer side of at least one wall and thereby forms a channel together with the wall. The cover strip preferably covers ventilation openings, which are introduced in the one wall. According to the invention, it is further provided that the shortest path between the parallel attachment strips along the overlay strip is longer than the shortest path along the at least one wall between the parallel attachment strips or the overlay strips. In other words, the cover strip has a greater width than the distance that the fastening strips occupy when the wall is flat, that is on a single plane. In a preferred embodiment, the overlapping strip has at least one folded edge along which its Inner wall is folded back on itself and / or the cover strip is fastened by a fastening strip with its inner surface to the at least one wall and secured to the other fastening strip with its outer surface on the at least one wall.

The overlay strip can be part of a flat web and in this case is preferably formed by the overlapping region of the two edges. In this case, the wall on which the cover strip is mounted is formed of two parts which are fastened together with a fixing strut, this fixing strip being at the same time one fastening strip of the covering strip.

However, the overlay strip may also be a separate strip attached to one of the two walls. In principle, even several overlapping strips are conceivable.

In an alternative embodiment of the invention, even a separate strip may be attached to the inside of the at least one wall, in which then at least one vent opening is introduced. In this case, the area of the at least one wall which lies between the fastening strips assumes the function of the covering strip, as described in connection with the preceding embodiments. In this case, it is thus provided that the shortest path between the parallel attachment strips along the overlay strip is shorter than the shortest path along the at least one wall between the parallel attachment strips.

In a further alternative of the invention, the shortest path between the parallel attachment strips along the overlay strip is the same as the shortest path along the at least one wall between the parallel attachment strips, but in this case the overlay strip comprises elastic material, ie, the shortest path between the two attachment strips along the overlap strip is extendable. The attachment strips may be formed by a material such as cold glue, hot melt, extrudate, or other additions which provide a fastening effect. However, such attachment strips may be produced without material addition, such as hot air sealing or welding, contact welding, ultrasonic welding, or similar methods. The fastening strips are preferably interruption-free, but may alternatively also comprise small interruptions, through which air can escape from the channel into the environment. Such breaks may be equivalent alternatives to the vents in the overlay strip.

The invention solves the above object by the following mode of action. When filling the contents in the bag is always, intentionally or unintentionally, air introduced into the bag. In a bag according to the invention, the latter can now enter the channel through the ventilation openings which are introduced into the bag wall. The vents can be large, so that the air within the shortest tent can escape from the interior of the bag. Due to the special nature or attachment of the overlap strip, the channel can now significantly increase due to the influence of the air and thus absorb a large volume of air. The stored air in the channel can now be slowly discharged to the environment through the vents in the cover strip and / or the interruptions in the mounting strip, and due to the slow discharge little or no of the contents of the bag is taken and therefore almost completely in Sack remains even if a small part of the contents remain in the channel. Thus, the bag can be filled with a very high speed, without the environment of the bag filling station is contaminated with filling material. The venting of the Kanai may then take a long time, even after the bag has already been closed.

In a preferred embodiment of the invention, the shortest path between the parallel attachment strips along the overlay strip at least 3% longer than the shortest path along the at least one wall. In this case, sufficient venting performance is provided, while at the same time efficiently handling the material used. In addition, it is advantageous if the shortest path between the parallel fastening strips along the covering strip is at most 20% and in particular at most 10% longer than the shortest path along the at least one wall.

It is also advantageous if a layer of a Fiitermaterial is provided within the channel. In this case, the filter material is arranged such that the air must pass therethrough, to get to the vents in the cover strip or to the interruptions of the fastening strips. In this case, the filter material is preferably fastened with a peripheral fastening seam on the covering strip and / or the at least one wall and / or the fastening strip. Such a filter material may be a pulp, such as paper, or a plastic fleece. The advantage of this design is that the filling material is retained by the filter material, in particular when it is a dusty filling material. In a further development, the filter material may even be moisture-absorbing, so that moisture entering through the ventilation openings can be absorbed by the filter material, so that the contents are protected from moisture as well as possible. In a further advantageous embodiment of the invention, a layer of a filter material is provided in the bag interior, wherein the filter material covers the vent openings of the at least one wall. Also in this case, it is advantageous if the filter material, which is present as a piece of material, is fastened with a peripheral connecting seam on the at least one wall, so that no air can flow through between the wall and the filter material. The connecting seam encloses all vents. This measure also prevents contents from getting into the environment. In an advantageous development, it is provided that the air permeability of the ventilation openings in the at least one wall is greater than the air permeability of the overlapping strip. For this purpose, the ventilation openings of the overlapping strip can be produced by a needle perforation. In this case, holes are produced with a maximum diameter of 0.8 mm. Microperforations, for example with a density of 5 to 30, in particular 13, vents per square centimeter (cm ³ ), and nanoperforations, for example with a density of 50 to 100, in particular 64, vents can often be used in connection with or else independently of the needle perforation per square centimeter (cm ³ ), differ from each other. For example, the perforations may be formed with substantially conical needles or with substantially cylindrical needles. The vents in the at least one wall can be easily introduced by the introduction of small cuts. For this purpose, a knife roller is preferably used. The advantageous effect of these aforementioned features is that in this way a very fast final ventilation of the bag interior can take place, wherein the air can then be stored in the channel in order to release it slowly to the environment. This can be effectively prevented that contents with the exiting air is released to the environment. Particularly good a Füllgutaustritt is avoided with the above-described micro or Nanoperforationen.

In a further advantageous embodiment of the invention, it is provided that the vent openings of the overlapping strip is a maximum of half a bag length, in particular a maximum of one third of the bag length, from which at least one base is removed. In particular, the at least one bottom means the lower bottom when, during filling, the sack is positioned substantially vertically. This is at the same time the soil that is first produced within an FFS machine. In this case, in particular when the ventilation openings, which are introduced into a wall, are arranged at the upper end of the bag, which is not yet closed during the filling, a labyrinth-like guidance of the air introduced with the contents is achieved. This will find parts of the product in the channel no direct path towards the environment, so that contamination of the environment is avoided.

It is also advantageous if the plastic bag has gussets and if the ventilation openings of the overlapping strip has at least one distance to the nearest weld seam, wherein the distance corresponds to the side fold depth. In this way, on the one hand, a maximum distance between the vents in the wall and the vents in the overlay strip can be achieved, so that a maximum labyrinth effect is achieved. In addition, there is the following effect. A filled bag assumes a cuboid shape, with the gussets forming and forming a side wall. Accordingly, the lower and upper end portions of the front and rear panels fold to form bottom and top surfaces. Now have the vents the specified distances to the welds, they are in the filled bag still in the front or the rear wall, so that further, after the bag has been placed horizontally, a venting possibility is given, if the channel then arranged at the top. In an advantageous embodiment of the invention it is provided that the plastic bag has side folds and that the channel extends over at least one outer corner or an inner corner of one of the side folds. This means that the cover strip also extends over at least one outer corner or over at least one inner corner. This may mean that at least one fastening strip is located on one of the walls of the side folds or that a fastening strip on the first wall and a fastening strip are located on the second wall of the bag. In this embodiment, it is advantageous that the channel of the filled bag is at least partially located on one of the side surfaces, so that there is no unwanted sealing of the ventilation openings through the leading bag or through the following bag. Thus, the (slow) venting of the channel is not disturbed, so that the bag can take better up to its palletizing the intended cuboid shape. In the variant in which the cover strip over only one outside corner is sufficient, this can be placed directly around the said outer corner, which then forms in the covering strip also an outer corner. In this case, the teaching of the invention is then automatically generated. The above-mentioned object is also achieved by a method according to claim 9. Accordingly, it is in a process for producing and filling a bag, in which

• a roll is provided with a tubular web,

• The tube web is unwound from the roll in an unwinding device

The tube web is provided with a bottom in a sack formation device at its leading end, preferably by creating a transverse weld seam,

• In the bag forming device a piece of hose is separated from the tube web

• The piece of hose is transported by means of moving holding elements to a filling device

The sack is filled with a filling material, wherein the air entering the interior of the sack with the filling material is at least partly discharged to the outside via vents in at least one outer wall of the sack,

The air is guided into a channel located on the outside of a wall,

provided that

by guiding the air into the canal,

which covers the vents and which is formed by at least two parallel attachment strips and a cover strip, the cover strip also having vents and wherein the shortest path between the parallel attachment strips along the cover strip is longer than the shortest path along the at least one wall between the parallel attachment strips or the overlay strip and / or the parallel fastener strips are made of stretchable material, the volume of the channel increases. Characterized in that the air is guided in the inventively designed channel, the contents can be filled at a high speed in the bag, wherein the channel can expand greatly. Thus, the registered with the filling air can be led out of the actual Füllgutkammer of the bag, without this gets into the environment. The latter fact is important because with a quick discharge of air often a part of the contents is entrained. According to the invention, however, air and filling material only reach the channel, which is used as a buffer. From here, the air gradually enters the environment, with the venting performance from the channel into the environment need not be very large.

In a further advantageous embodiment of the invention it is provided that after filling the bag is transported at least by further movable holding elements to a closing device in which the bag is closed at its second end. Both the transport and the closing can now take place at a high speed, since the air introduced into the interior of the bag with the filling material has now been discharged essentially into the channel, resulting in a flat head region, which can easily be welded by means of welding devices , In particular, in an embodiment in which the channel ends below the subsequent head weld, this also does not interfere with the optionally still inflated channel.

In a further embodiment of the method according to the invention it is provided that the bag is placed after closing at its second end to a transport device, so that the overlap strip to the top and / or to one of the side surfaces shows. In this case, the air that is still in the channel, can be discharged through the second vents, this process can be done slowly. A substantially complete venting must be done when the piled sacks are stacked on a pallet. There is still some time left before palletising, which can be used to vent the canal. However, venting is easier when the duct is in contact with the environment through the vents. A By contrast, venting would not take place quickly enough if the bag rests with the channel side on a support surface, such as a conveyor belt.

The above object is further achieved by a device for producing and filling of bags according to claim 12. Accordingly, in an aforementioned apparatus comprising:

An unwinding device in which a tubular web can be unwound from a roll,

A sack formation device in which the tubular web can be provided with a bottom at its leading end, wherein preferably a welding device is provided for producing a transverse weld seam, and in which a piece of hose can be separated from the tubular web,

• movable holding elements, with which the hose piece can be transported to a filling device

• A filling device, in which the bag with a filling material can be filled, wherein the entering with the contents into the interior of the bag air is at least partially via vents in at least one outer wall of the bag to the outside can be derived, the air in a on the Outside of a wall of the sack channel is feasible,

provided that

at least one means for promoting the venting is provided, with which the guiding of the air into the channel, which covers the ventilation openings and softer at least by two parallel Befestigungshelelfen and a cover strip is formed, wherein the cover strip also comprises vents and wherein the shortest path between the parallel fastener strips along the overlay strip is longer than the shortest path along which at least one wall between the parallel fastener strips or the overlay strips and / or the parallel fastener strips of stretchable material is favorably enhanced with the volume of the channel being increased. By means of a device for promoting ventilation, it is thus meant that a component of the production and filling device according to the invention is configured in such a way that it itself or the action which can be carried thereby is conducive to the escape of the air into the channel. In particular, such a device is preferably designed such that it leaves the channel unaffected in its properties. In other words, the functionality is also given after the action of the device.

In a first advantageous embodiment of the invention it is provided that the device for promoting the vent comprises at least one welding bar, which is adapted to the contour of the bag in the region of the overlapping strip. In particular, this may mean that the contour of the at least one welding bar, with which either the bottom seam or the top seam can be formed, comprises a flat surface, which, however, comprises a depression in the region in which the channel is located. In this way it is ensured that the channel is not damaged by a too high temperature and / or by excessive contact pressure and / or by a too long welding time. Damage would be, for example, a melting of the overlap strip, which would have the consequence that air and also contents could get through the unwanted openings into the environment.

In a further preferred embodiment of the invention, a device for promoting the vent is provided, which comprises at least one transport and / or guide roller whose diameter is varied seen in the axial direction. In particular, it is provided that this transport and / or guide roller comprises a recess which serves to guide the channel. This means that only the areas of the hose walls which lie outside the channel, rest during transport by means of the transport or guide roller on the outer surface.

It is advantageous if in the device according to the invention the device for promoting the vent comprises at least one web guiding device, with which the tubular web can be guided, wherein the web produced ski piece comprises a cover strip, which points in the filling station in the direction of the bag-forming device. This web guide device may consist of guide elements, such as web guide rollers, which guides the tubular web so that the mentioned features are met. A web guiding device may also include an unwinding device which comprises an unwinding shaft which can rotate in two directions of rotation. Thus, it is then possible to handle a tubular web roll according to the above goal. In this case, it is not necessary to make sure that the channel is pointing in a specific direction when winding up the tube web. However, a web guide may also include a turning station that alters the position of the channel as needed. The advantage of the embodiment in which the overlap strip points in the direction of the tube forming device is that an already filled bag, which is arranged in front of the bag just to be filled in the transport direction, can not disturb the expansion of the bag currently to be filled. Thus, a good venting of the bag is ensured.

In an advantageous embodiment of the invention it is provided that the means for promoting the vent comprises at least one depositing device, with which the bag with its head end in the transport direction pointing to a transport device can be stored, so that the cover strip to the top and / or to one of Side faces shows. In this case, the means for promoting the vent may be an impact element, such as a rod, a sheet or even the gripper tongs of the closing station. It is provided that the push element is movable in the transport direction of the bag and at least in the period in which it is in touching contact with the head portion of the bag, at least partially movable with a transport speed which is greater than the instantaneous transport speed of the bag. The head region of the bag is preferably the upper half of the bag (if this is still aligned vertically after filling), in particular the top third of the bag. By the action of a shock element or an equivalent means a simple overturning of the bag in the transport direction, so that to transport this lying by means of a transport device, wherein preferably shows the main axis of the bag in the transport direction. With this embodiment, it is possible to arrange the bag on the transport device that the channel up and / or to the side, so that the air stored in the channel can be discharged through the vents of the overlap strip for a long time to the environment, without while also leaking füilgut.

Furthermore, it can be provided in an advantageous embodiment of the invention that the means for promoting the vent comprises at least one vibrating device, with which the filling material is set into vibration. Such a vibrating device may be a knocking device which operates at a high amplitude but low frequency. Alternatively or additionally, this vibrator may be a vibration generator which operates at a lower amplitude but at a higher frequency. A vibrating device can act on the bag directly or via an intermediate element, such as a carrying device or a conveyor belt of a transport device. Preferably, the vibrating device may be arranged below the filling station, so that the filling material can still act on the sack during the filling of the sack or immediately thereafter. In this case, the air introduced into the bag with the contents can escape into the channel. A vibrating device is advantageously also be arranged in the region of transport devices on which a bag rests after closing. In this case, residual air within the bag can still escape into the channel and then into the environment.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the figures, various embodiments are explained in detail. In this case, the Merkmaie mentioned in the claims and in the description can each be individually inventive for themselves or any combination of mentioned features. Throughout the disclosure, features and details that are described in connection with the method according to the invention, of course, also apply in the Connection with the device according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention is always reciprocal reference or can be. The same applies with regard to the disclosed features of a bag according to the invention, which also in any combination with Merkmaien of the inventive method and / or the device according to the invention or vice versa. Also, features that are or have been described in connection with further features may also be independent of these further features aHeine or in combination with any other features inventive features. Also on these feature combinations can be mutually referenced. The individual figures show:

Fig. 1 section through a first embodiment of a bag according to the invention

Fig. 2 section through another embodiment of a bag according to the invention

Fig. 3 section through a further embodiment of a bag according to the invention

Fig. 4 section through a still further embodiment of a bag according to the invention

5 shows a section through a further embodiment of a bag according to the invention

6 shows a step for producing a bag according to the invention

Fig. 7 showing a further step for producing a bag according to the invention

8 shows a still further step for the production of a bag according to the invention

9 shows a longitudinal section through an embodiment of a bag according to the invention

10 shows a longitudinal section through a further embodiment of a bag according to the invention

11 is a schematic diagram of a first embodiment of a erfingungsgemäßen FFS system

12 is a schematic diagram of another embodiment of an inventive FFS system

13 shows a component in an FFS system according to the invention, FIG. 14 shows a roller in an FFS system according to the invention

FIG. 1 shows the cross section through a first embodiment of a plastic bag 1 according to the invention. It comprises a first wall 2, which in the present example represents the rear wall. This first wall is connected via the gussets 3, 4 with the second wall 5, which represents the front wall. The gussets 3, 4 each comprise two gusset panels 6 'and 6 "or 7' and 7", the gusset panels 6 'and 7' being connected to the second wall 5 via outer edges 8 'and 9', respectively, and the gusset panels 6 "and 7". via outer edges 8 "and 9" connected to the first wall 2. The gusset walls 6 'and 6 "or 7' and 7" are connected to each other via inner edges 9 and 10, respectively.

The front wall 5 is formed by a first region 11 and a second region 12. The edge 13 of the first region 1 1 is fastened with a fastening strip 14 on the surface facing the bag interior 15. The strip passing over the fastening strip 14 forms a covering strip 16 which covers the ventilation holes 17 of the second wall 5. The overlay strip 16 is connected to its edge 18 via a fastening strip 19 on the outer surface of the first region 6 of the second wall 5. In this case, the covering strip 16 is fastened with its outer surface to the first region 6, so that a U-shaped fold 20 or in the flat state a double-ply region of the overlapping strip is formed. In this way, a channel 21 is formed, the volume of which is variable over a very wide range. This channel further comprises vent openings 22, so that the air that has passed from the interior of the bag into the channel can escape into the environment.

By means of the fastening strip 14, the covering strip 16 can be delimited from the region 12 of the front wall 5. On the surface of the overlay strip 16 facing the channel, a filter material 23 is preferably provided, which is attached to the overlap strip via two attachment strips 24.

FIG. 2 shows a further exemplary embodiment of a plastic bag 1 according to the invention. Instead of the U-shaped fold of the covering strip 16, a z-shaped fold 26 is provided in this exemplary embodiment, which is created by creating a double fold. The z-shaped fold is characterized by the fact that three layers are formed here. Although it can be seen in FIG. 2 that the z-shaped fold 26 is arranged in the region of the fastening strip 19, the z-shaped fold can be arranged at any desired position between the fastening strip 14 and the fastening strip 19. Also, several z-shaped folds 26 are conceivable.

In the embodiment of Figure 3, the overlap strip 11 of the valve bag 1 even comprises a z-shaped fold 21 and a u-shaped fold 15. The features of the embodiments according to Figures 1 to 3 can be combined with each other. However, it is important in all cases that the length of the path defined by the line of overlay strip 16 visible in the figures between the fastening strip 14 and the fastening strip 19 be greater than the length of the path visible through the figures Line of the second wall 5 between the fastening strip 14 and the Befestigungsstrelfen 19 is fixed. It is preferred if the difference in length is at least 3%.

FIG. 3 shows a further embodiment which can also be combined with all other exemplary embodiments disclosed in this patent application. In this case, the overlay strip 16 is fastened to the region 11 of the front wall 5 with a third attachment strip 27. This third fastening strip 27 divides the channel 16 into a first partial channel 28 and a second partial channel 29, wherein the ventilation openings 17 from Sack interior 15 lead into the first sub-channel 28. The vents 22 lead from the second sub-channel 29 into the environment. So that now the air from the first sub-channel 28 can get into the second sub-channel 29, the fastening strip comprises at least one interruption. Preferably, the at least one interruption is so long that the venting performance of the bag is not impaired.

In the embodiment of Figure 4, in contrast to the embodiments of Figures 1 to 3 of the overlap strip 16 is formed as a separate workpiece. He is therefore not integrally formed with a part of the front wall 5. This separate cover strip 16 is fastened on the front wall 5 of the valve sack via the two fastening strips 14, 19. As an example, it is shown that the overlay strip 16 includes U-shaped folds 20 at its two edges. The front wall 5 and the rear wall 2 of the plastic bag 1 may already have been made as a hose, for example by a blown film extrusion process or a Rundwebverfahren. However, a hose may also have been made from a flat web, in which the two side regions have been turned over to form an overlap and in which the overlapping edges are joined by a joining seam.

A further exemplary embodiment is shown in FIG. 5, in which the overlapping strip 16 extends over the outer corner 8 '. The fastening strip 14 is located on the front wall 11, while the fastening strip 19 is arranged on the side gusset wall 7 '. The vent openings 17 can, as shown in Figure 5 is, be arranged in the side gusset wall T. The cover strip may also extend over another or over several of the outer corners. With regard to the u- and / or z-shapes of the edges, the overlapping strip may be designed according to one of the figures 1 to 4 or a combination thereof. In the present embodiment, however, it is also possible, deviating from providing no u- or z-shaped refolding, but instead provide a refolding in the region of the outer corner 8 ', which is, however, spaced therefrom, so that according to the invention Path between the fastening strip along the overlapping strip is longer than along the front wall and the side gusset wall 7 '.

FIG. 6 now shows some steps of a method according to the invention for producing a plastic bag. For this purpose, a flat web 50 is first handled by a unwinding device, not shown. Subsequently, the introduction of ventilation openings, again not shown, of which a few vents 22 are shown by way of example. These vents are preferably not continuously introduced in the longitudinal direction of the flat web, but intermittently. For this purpose, a roller roll on the flat track, the peripheral surface is only partially occupied with needle, cutting or punching tools. Alternatively or additionally, it may be provided that such a roller is brought into contact with the flat web 50 at the locations where vents 22 are to be introduced. For this purpose, a pitching mechanism can be provided, which cyclically brings the roller into contact with the flat track. The flat web preferably runs over a counter-roller.

In the same way, the vent openings 17 can be introduced into the flat web 50. In this case, however, a roller 51 is shown, with which individual, short cuts in the flat web 50 are generated. The peripheral surface 52 of the roller 51 is for this purpose covered with knives 53, wherein each two adjacent knives can assume an angle to each other, in particular a right angle. Also, for the roller 51 may be provided a pitch mechanism which cyclically brings the roller into contact with the flat track. The adjusting mechanism for the roller 51 operates independently of the adjusting mechanism mentioned in the preceding paragraph, since the ventilation openings 12 and 17 are preferably offset in the transport direction of the flat web introduced.

After the introduction of the vent openings 17 and before or after the introduction of the vent openings 22, the flat web 50 can be covered with a filter material 55 which is attached to the flat web 50. This filter material can be applied in web form on the flat web. For this purpose, the fiiter material can be made available as a roll and unwound within a unwinding device. For attachment of the filter material can be provided that the filter material is already provided in its roll form with two lateral adhesive strips. However, it is advantageous if two adhesive traces 56, 57 are applied to the flat web and / or to the web-shaped filter material, wherein the vent openings 17 lie completely within these traces of adhesive. The traces of adhesive may include a dispersion adhesive, a hot-melt adhesive or a cold glue; but they can also comprise an extrudate. In the latter case, plastic is converted into a melt in an extruder and applied in this form through nozzles as traces. Preferably immediately after the application of the adhesive traces the flat web and the web-shaped filter material are joined together, which is indicated by the arrows 58, and - pressed together, for example by means of a press roller pair, not shown - and possibly also cooled.

In another embodiment, the filter material 55 may also be applied in the form of a label to the flat web, wherein the filter material is at least dimensioned so that it completely covers the vents 22 concentrated on a surface portion. To prepare the filter material in slip form already pre-assembled labels can be used. However, it is preferred if here too the filter material is in roll form and is separated into slips by a dicing tool, for example by a cutting tool. Adhesive traces are now preferably applied to the flat web 50, wherein a circumferential trace of adhesive is produced, so that the air to pass through the filter material can not escape through a gap in the adhesive trace.

The described procedures for applying filter material can also be used if the vents 17 are to be covered with a filter material.

In FIG. 7, the folding over of the side regions of the flat web 50 is now taking place, wherein preferably at the same time the gussets 3 and 4 according to FIG. 1 are introduced and wherein the rear wall 2 and the two areas 1 1 and 12 of the front wall 5 are formed. In this case, it is advantageous if the area 11 has already been folded over at a fixed location than the area 12. Even before or during the turning over of the area 12, the u-fold 20 is preferably produced. Alternative or additional folds can now also be introduced. Nevertheless, it is possible that even after the handling of the areas 1 1 and 12, the wrinkles described can be introduced. FIG. 8 shows the regions 11 and 12 which have already been folded over and which are now fastened together with the fastening strips 14 and 19. For this purpose, in an advantageous embodiment, two extrusion nozzles, which introduce at least one molten plastic material in the form of at least two parallel tracks between the regions 11 and 12 and thus delimit the channel 21. With at least one pressing device, not shown, for example, a pressure roller, the areas 1 1 and 12 along the mounting strips 14 and 19 can be connected to each other, so that a durable and durable connection can be generated. At least one cooling device can be provided in order to be able to cool the fastening strips, in particular if they have developed under the action of heat. The cooling device may be comprised by the pressing device. For example, pressure rollers can be cooled.

The method steps which have been explained with reference to FIGS. 6 to 8 can be carried out with a hose-forming device which, together with a device according to the invention, can form a system for forming plastic bags made of flat web material.

9, a sack 101 produced by the FFS process - referred to for short as a "sack" - can now be seen, which is preferably produced from a hose according to the exemplary embodiments of FIGS 1 to 7. In order to produce a sack 101 from such a hose , This tube is first at its leading end with a weld 120 - the so-called bottom weld, which is transverse to the main extension direction of the Sacks 101 runs (transverse weld), provided and then isolated from the hose to a piece of hose with the desired length, so that an upper, unlocked sack end is formed. Now, the piece of tubing by means of transport organs, which attack in the region of the upper end of the bag, such as transport gripper, brought to a filling station. In the filling station, the unsealed end of the bag is opened, so that a filling opening is formed, via which the filling material can be filled. In the filling station and in particular during filling of the bag is held by holding members - here are gripper tongs advantageous. After the bag has been filled, it is transported to the closing station, inter alia, by further transport members, which in turn engage in the area of the upper end of the bag, in which a weld 121 is produced at the upper end of the bag in order to close the bag. In this weld, which can also be referred to as a head weld, it is also a transverse weld.

It can be seen that the second wall 5 continues to the welds and beyond. As already explained, the wall 5 comprises the channel 21, which is delimited by the fastening strips 14 and 19, which are not visible here. Furthermore, it can be seen that the vent openings 22 are arranged closer to the valveless bottom than the vent openings 17. Preferably, the distance of the vent openings 22 to the bottom 102 is a maximum of a third, preferably a maximum of a quarter, in particular one fifth of the total bag length L. With bag length L. The shortest distance between the welds 120 and 121 is meant when the bag 101 is not yet filled and the walls 2 and 5 still have at least partially contacting contact with each other.

Conversely, it is provided that the vent openings 22 are arranged closer to the weld bead 121 than the vent openings 17. Preferably, the distance between the vent openings 12 to the weld 121 is at most a third, preferably a maximum of a quarter, in particular one fifth of the total bag length L. Due to the aforementioned Arrangement and in particular the distance of the vents relative to each other must the escaping air travel a long distance within the channel 21, whereby the flow velocity is reduced, so that entrainment of contents is reduced. FIG. 10 shows a further embodiment of a bag according to the invention. This embodiment is similar to the embodiment of Figure 9. The difference is that the overlay strip 16 does not extend to the bottom weld 120 and / or to the head weld 121, but with its one end in the area between the vent openings 22 and the bottom weld 120 and with its other end between the vents 17 and the head weld 121 ends. In this embodiment, the ends of the overlay strip are preferably secured to the wall 5 by further attachment strips 130, 131 to provide a seal of the channel 21 to the environment. The fastening strips preferably run transversely to the longitudinal extent of the bag 101.

FIG. 11 now shows a schematic diagram of an FFS installation 200 according to the invention. This FFS installation is intended for producing, filling and closing sacks with a filling weight of more than 5 kg.

First, a wound-up tube 201 in the form of a roll 202 is unwound in an unwinding device 203. The unwinding in the unwinding direction R is accomplished in particular by a feed roller pair 204, of which at least one of the two feed rollers is rotationally drivable by means of a drive. Immediately before or immediately behind the feed roller pair, a web storage device may be provided, preferably in the form of a dancer, so that the cyclical benefit of the hose required in the FFS system can be performed, even if the hose is withdrawn from the reel at a substantially constant speed ,

With the wavy line 205 of the overlay strip 16 is symbolized, whereby it depends here that this at the point shown on the the upper side of the hose is arranged. In other words, the overlap strip is arranged on the outside of the wound on the winding tube. The Vorzugswalzenpaar 204 and the optionally subsequent dancer device may be disposed downstream of a first welding device 206 in the transport direction of the hose, with which, for example Eckabschweißungen, ergängende Querschweißungen that detect the tube completely or partially in its width, and / or Längsschwei tions of the hose , Seen in the transport direction in the further course, a cooling device 207 can now be provided with which the welded connection produced can be cooled again. Instead of or in addition to the welding and / or cooling device, other processing devices such as a perforation device and / or a punching device may be provided, which can provide the tube with perforations or punches for better handling of the later bag.

This is followed by a deflection roller 208, which now feed the hose to a register device consisting of two further rollers 209 and 210. For this purpose, the rollers 209 and 210 are displaceable relative to each other, so that by changing the path of the hose, the position of welds, perforations, punches, but also imprints or other regularly recurring properties of the hose with the following processing equipment can be adjusted.

After passing over a further guide roller 21 1, the hose is passed through a further feed roller pair 212 in a combined transverse welding and separating device 213. This device 213 comprises, viewed in the feed direction, first a transverse welding device for producing a bottom seam on the hose. Below this cross-welding device is followed by a cross-cutting device, with which a piece of tubing, to which in the directly preceding it Machining stroke a transverse weld was attached, disconnected from the hose. Already before the separation, transporting means, not shown, take the piece of hose and spend it, if necessary also by means of further conveying members, in the filling station 214.

In the filling station are holding members that hold the piece of tubing or the bag 101st so that it remains in a substantially vertical position during filling. Opening means, which are also not shown, can serve to open the filling opening of the bag, so that a hopper 215 can be inserted into the bag interior. Subsequently, the filling of the filling material in the bag is possible, which is illustrated by the arrow 216. During filling, the bag can rest on a support device, so that the bottom weld, which may not yet completely cooled, is not overburdened. In the exemplary embodiment shown, the support device is shown as transport 217, which is provided in addition to the support function for the further transport of bags to follow-on stations. Furthermore, at least one vibrating and / or knocking device is provided, which can act on the sack from the outside in order to set it in motion in this way, for example in vibrations. This shaking and / or knocking device can be integrated in the support device. By the shaking and / or knocking the contents can be compacted. This means that air that is still inside the medium escapes and escapes through the vents, for example.

With the means of transport 217, the filled bag is moved in the transport direction z, wherein not shown transport organs, preferably gripper, hold the bag at the upper end, on the one hand to prevent the bag from falling over and keep the two walls in touching contact, so that a defined Head weld can be attached. This head welding takes place in the closing station 218. The welding tool is symbolized by the two arrows 219. The arrows indicate the direction of movement of parts of the welding tool. The closing station 218 can optionally also connect a cooling station 219, which is constructed similarly to the closing station, but instead of welding tools, comprises cooling tools in order to cool the weld seam created to close the bag and thus make it immediately loadable.

In the further course of the still upright arranged bag will be transferred to a lying position, as it is indicated with the bag 101 '. In this case, an element of the FFS system acts on the head area so that it is moved at a lower speed in the transport direction z than the ground area moved further by the means of transport. This has the consequence that the bag 101 'is transported in the further course with leading bottom. Accordingly, the overlap strip and the ventilation openings are at the top, ie on the transport means 217 facing away from the wall of the bag. In this way, the venting of the bag is still guaranteed in the event that the registered with the contents of the air has not yet completely escaped.

The speed difference described can be caused by the fact that, for example, the welding tools, cooling tools and / or transport organs do not completely release the bag while the transport already moves the bag further. Alternatively, a rod 220 may be provided, which extends in the transverse direction and, for example, is fixedly arranged in the FFS system. In this exemplary embodiment shown in FIG. 11, the overlapping strip of the bag is arranged on the leading wall in the transport direction z. This embodiment is simple to realize with respect to the later transport position with "ground-ahead" since no separate, moving machine element is needed, but it should be noted that the filling station 214, the closing station 218 and the cooling station are sufficiently far apart from each other, such that a leading sack does not touch the sack immediately following so strongly that the overlay strip is pressed flat, in which case the venting property would be ineffective. In the alternative exemplary embodiment of FIG. 12, the hose is unwound in an unwinding direction R 'opposite to that in FIG. 11, so that the overlapping strip, again represented here by the wave-shaped line 205, is located on the underside of the hose. Alternatively, the unwinding direction R can be provided according to Figure 11 and thereby a winding can be used, on which the tube is wound such that the overlap strip points inwards.

Both measures have the consequence that - especially in the filling station - seen in the transport direction z, the subsequent wall carries the vent strip so that it can expand in the filling station, unhindered by other sacks, to accommodate the largest possible volume of air can. The FFS system itself is unchanged compared to FIG. 11 up to and including the cooling station 219. Therefore, both the reference numerals and also the description parts of FIG. 11 can be transferred to FIG. 12, but for the sake of clarity, this is dispensed with. However, in an FFS system 200 according to FIG. 12, it is necessary to accelerate the bag with its head end in order to bring it to a lying position with a leading-up seam on the transport means. For this purpose, a rod 220 may be suspended in a rotating device. For example, it may be arranged eccentrically on a turntable whose axis of rotation runs parallel to the extension direction of the rod 220. Thus, the rod 220 can perform a movement in the direction of the arrow 221 and thus - assuming a sufficiently high rotational speed - accelerate the head portion of the bag. At this point, however, numerous embodiments are possible, but all are included in the present inventive concept with.

FIG. 13 shows a component 300, which can preferably be used within an FFS installation 200, in order to ensure reliable operation even when processing hoses with cover strips. This component may be the jaws of a welding device with which For example, head and / or bottom welds to the hose, a piece of hose and / or sack are attachable. Component of this component are the two jaws 301 and 302, which are for example heated welding jaws, the jaw 302 is provided with a recess 303, which is adapted to the position of the overlay strip. This ensures that the jaw 302 are acted on all parts of the wall to be acted upon with heat with the same heat transfer, so that a proper training, for example, the weld occurs. If the jaw 302 does not mate with this recess, it could happen that the cover strip is welded through and thus destroyed, while other areas of the wall do not receive sufficient heat for welding. The jaws may also be part of a cooling device within the FFS system.

FIG. 14 shows a roller 400 which may be provided as a deflection, transport, conveying, preferential and / or guide roller in an FFS system according to the invention. A region 401 with a diameter which is smaller than the diameter of the remaining regions 402 is provided. In order to produce such a roll 400, initially a roll body of constant diameter can be produced over the roll length. Subsequently, machining can be carried out in the region 401, for example by turning or milling. In a likewise advantageous embodiment, a roller 400 may be provided, the roller body of which has a uniform diameter over the entire length of the waffle, in which case, however, sleeves may be pushed onto areas of the roller body. These sleeves then form the regions 402. In this way, by moving and / or exchanging sleeves, the position of the region 401 can be displaced in the axial direction and / or the width of the region 401 can be varied. The roller 400 is rotatably supported by pins 403 in the machine frame or its attachment parts of the FFS system.

A roller 400 is preferably provided at such locations within the FFS system where the hose must be guided so that the overlay strip faces the roller surface. When using a conventional constant diameter roll over its length, it can happen because of the uneven contact surface of the hose runs laterally. This is avoided by the provision of a roller 400.

Claims

1. Plastic bag, in particular FFS bag, comprising

a first wall and a second wall which are interconnected by side edges or gussets and by bottoms and define a sack interior,

wherein at least one bottom comprises a weld which extends between and touches the side edges or gussets,

Vents in the first and / or in the second wall for venting the sack interior,

characterized in that

at least one channel is provided on the outside of at least one wall which covers the vent openings and which is formed by at least two parallel attachment strips and one cover strip, the cover strip also comprising vent openings and wherein the shortest path between the parallel attachment strips along the cover strip is longer the shortest path along the at least one wall between the parallel attachment strips or the cover strips and / or the parallel attachment strips made of stretchable material. 2. plastic bag according to claim 1

characterized in that the shortest path between the parallel attachment strips along the overlay strip is at least 3% longer than the shortest path along the at least one wall. 3. Plastic bag according to one of the preceding claims

characterized in that

a layer of filter material is provided within the channel. 4. plastic bag according to one of the preceding claims

characterized in that

a layer of filter material is provided in the sack interior, the filter material covering the vents. 5. Plastic bag according to one of the preceding claims,

characterized in that

the air permeability of the vents in the at least one wall is greater than the air permeability of the overlay strip. 6. plastic bag according to one of the preceding claims,

characterized in that

the vents of the overlap strip are at most half a bag length, in particular at most one third of the bag length, away from at least one floor. 7. Plastic bag according to one of the preceding claims,

characterized in that

the plastic bag has gussets and that the vent openings of the overlap strip has at least one distance to the nearest weld, the distance corresponding to the side fold depth. 8. Plastic bag according to one of the preceding claims,

characterized in that

the plastic bag has gussets and that the channel is above least one outer edge or inner edge of the gusset extends. 9. A method for producing and filling a bag, in particular a bag according to any one of the preceding claims, wherein

• a roll is provided with a tubular web,

• The tube web is unwound from the roll in an unwinding device

• In the bag forming device a piece of hose is separated from the tube web

■ The tube piece is transported by means of moving holding elements to a filling device

The air being conducted into a channel located on the outside of a wall,

characterized in that

by guiding the air into the canal,

which covers the vents and is formed by at least two parallel attachment tabs and a cover strip, the overlay strip also including vents, and wherein the shortest path between the parallel attachment tabs along the cover tab is longer than the shortest path along the at least one wall between the parallel attachment tabs or the overlay strip and / or the parallel attachment strips are made of stretchable material, the volume of the channel is increased. 10. Method according to the preceding claim,

characterized in that after filling the bag at least by further movable Haiteelemente is transported to a closing device in which the bag is closed at its second end. 11. The method according to the preceding claim, characterized in that the bag is placed after closing at its second end to a transport device, so that the cover strip to the top and / or to one of the side surfaces shows. 12. An apparatus for producing and filling a bag, in particular for carrying out a method according to one of the three preceding claims, comprising:

An unwinding device in which a tubular web can be unwound from a roll,

A filling device in which the sack can be filled with a filling material, wherein the air entering the interior of the sack with the filling material can be diverted to the outside at least partially via vents in at least one outer wall of the sack,

The air being ductable into a channel located on the outside of a wall of the bag,

characterized in that

at least one device for promoting the ventilation is provided, with which the guiding of the air into the channel,

which covers the vents and which is formed by at least two parallel attachment strips and a cover strip, the cover strip also comprising vents and wherein the shortest path between the parallel attachment strips long of the overlap strip is longer than the shortest path along which at least one wall between the parallel attachment marks or the overlay strips and / or the parallel attachment strips of stretchable material is favored, whereby the volume of the channel increases. 13. Device according to the preceding claim, characterized in that the means for promoting the vent comprises at least one welding bar, which is adapted to the contour of the bag in the region of the overlap strip. 14. Device according to one of the two preceding claims, characterized in that the means for promoting the vent comprises at least one transport and / or guide roller whose diameter is varied seen in the axial direction. 15. Device according to one of the three preceding claims, characterized in that the means for promoting the vent comprises at least one web guide device with which the tubular web is feasible, wherein the piece of hose produced from the web comprises a cover strip, in the filling station in the direction of Sacking device shows. 16. Device according to one of the three preceding claims, characterized in that the means for promoting the vent comprises at least one depositing device with which the bag with its head end in the transport direction pointing to a transport device can be stored, so that the overlap strip to the top and / or pointing to one of the side surfaces. 17. Device according to one of the four preceding claims, characterized in that the means for promoting the vent comprises at least one vibrator, with which the filling material is set in vibration.