EP3017940B2 - Method and a device for the production of bags from tubular bag bodies - Google Patents

Description

The invention relates to a method and a device for producing sacks from tubular sack bodies, wherein the sack bodies are preferably made from a fabric made of plastic tapes or a nonwoven plastic material (e.g. plastic fleece) or a composite made of the fabric made of plastic tapes and the nonwoven plastic material or a plastic film connected to a net structure, wherein the material is optionally coated on at least one side with at least one plastic layer and/or at least one plastic film, e.g. an OPP film. The sack bodies are transported on a transport device lying flat across their longitudinal extent at a transport speed in a transport direction, wherein the sack bodies pass through processing stations during their transport, with which at least one end region of each sack body is formed into a cross bottom and optionally a cover sheet is applied to the cross bottom.

Box sacks, also known as cross-bottom sacks, are cuboid-shaped sacks that are manufactured in sack-making plants by providing tubular sack bodies whose open end areas are folded into cross bottoms. The sack bodies are fed through the manufacturing plant lying flat so that two layers of the tubular sack body lie against each other. To form the bottom, the two layers are separated from each other at the end areas of the tubular sack body and one of the two layers is folded over on itself by 180° as a side flap, creating an open bottom with the other layer forming a second side flap. By folding over a layer at the end area of the tubular sack body, a triangular corner fold is created at the front and rear part of this end area. In technical terms, this process is also called "pulling on". In a further processing sequence, valve sheets can be inserted (to produce "box valve bags" that can be filled through the valve with a filling nozzle) and the final bottom configuration is produced by folding in the bottom side flaps so that they overlap. The overlapping bottom side flaps are glued or thermally welded together depending on the material of the bag body. Alternatively or additionally, bottom cover sheets can be placed on the overlapped bottom side flaps and glued or welded to them. Such a bag assembly system is described in the patent AT 408 427 B described.

The throughput of bag manufacturing systems is largely dependent on the transport speed at which the tube sections to be assembled are transported through the assembly system. The disadvantage of the patented AT 408 427 B The known sack manufacturing plant has shown that the cyclical operation of this plant limits the throughput of sack bodies to be processed. The time required for the cyclical pulling on of the bottoms, including the necessary fixing of the pulled on bottoms, can even represent an upper limit for the performance of the entire device for producing sacks.

This disadvantage was overcome by the EP 2 441 574 B1 disclosed device for forming open bottoms on bag bodies, which enables continuous conveying of the bag bodies, which led to an increase in transport speed and productivity.

The transport speed of bag bodies in bag making plants could be further increased by the EP 2 711 166 A1 described invention, with which the cycle frequency of a workpiece holder in the transfer area of bag bodies from their longitudinal transport to their transverse transport was increased.

Increasing the transport speed has now reached the limits of the performance of the equipment arranged along the transport path of the bag bodies for forming the cross bottoms, in particular hot-air welding equipment for attaching bottom cover sheets and/or valves to the bag bodies. Therefore, an increase in the throughput of bag assembly systems cannot be achieved by further increasing the transport speed of the bag bodies.

In state-of-the-art assembly lines for box bags or box valve bags, tubular bag bodies are fed transversely to their longitudinal extension to a continuously running transport device and pass through various processing stations along their transport, such as a bottom opening device. Such an assembly line is in Fig. 8 shown schematically. When the sack bodies are transported in the transverse direction, the repeat (x), which is the distance between the front longitudinal edges or the rear longitudinal edges of two consecutive sack bodies (10), is usually fixed and remains constant even when processing tubular sack bodies of different widths (b). The throughput of sack bodies through the sack assembly system is therefore essentially dependent on the transport speed (V) of the sack bodies being transported and the repeat. In the case of sack bodies of a small width (b) in particular, the fixed repeat (x) results in relatively large distances (y) between the sack bodies (10), which prevent the transport potential of the sack assembly system from being fully exploited.

A further disadvantage of the fixed repeat is that hot air welding devices, which are required for attaching the bottom cover sheets, run empty between the successive bag bodies or successive bottom cover sheets, whereby considerable energy in the form of hot air is released unused into the environment, since switching the hot air welding devices off and on again between successive bags is not possible for process-related reasons.

DE1216196B reveals that the obvious idea of reducing the workpiece speed after the workpieces have been removed from the longitudinal conveyor area, which would also reduce the distance between the workpieces, is not implemented in practice because of the complexity and cost of the device. DE1216196B The implementation of the discussed idea is therefore explicitly discouraged. It is therefore an object of the present invention to increase the throughput of bag bodies in bag assembly systems without increasing the transport speed of the bag bodies.

This object is achieved by a device and a method for producing bags from tubular bag bodies having the features of claims 1 and 9, respectively.

Advantageous embodiments of the invention are set out in the subclaims and the following description.

The device according to the invention and the method according to the invention for producing bags from tubular bag bodies are particularly suitable for processing bag bodies which are made from a fabric made of plastic tapes or a nonwoven plastic material (e.g. plastic fleece) or a composite made from the fabric made of plastic tapes and the nonwoven plastic material or a plastic film connected to a net structure, wherein the material is optionally coated on at least one side with at least one plastic layer and/or at least one plastic film, e.g. an OPP film.

The bag bodies are transported lying flat transversely to their longitudinal extension at a transport speed in a transport direction, whereby at least one end region of the bag bodies is formed into a cross bottom during their transport and optionally a cover sheet is applied to the cross bottom.

Sack bodies to be transported are moved by at least one transfer device by a feed distance in the transport direction in relation to sack bodies transported at transport speed and then moved at the transport speed, the movement of the sack bodies on the feed distance taking place at least in sections at a transfer speed that is greater than the transport speed. This measure adjusts the length of the repeat and can be set to a predefined distance between adjacent sack bodies by calculating and controlling the feed distance depending on the width of the sack bodies so that the predefined distance between successive sack bodies or between the cover sheets of successive sack bodies results. So that the device according to the invention can be operated automatically, the width of the sack bodies is detected by a sensor. According to the invention, the device comprises a control system which calculates the feed distance depending on the width of the sack bodies so that a predefined distance between successive sack bodies or between the cover sheets of successive sack bodies results. The controller controls the transfer device according to the calculated feed distance, wherein the controller controls the speed at which the transfer device moves the bag bodies in the transport direction according to a speed profile which includes accelerating to the transfer speed and, after a period of time dependent on the length of the feed distance, braking to the transport speed.

In order to ensure gentle handling of the bag bodies and to ensure that they are picked up and transferred to the transport device precisely, the speed at which the bag bodies are moved on the feed path is controlled according to a speed profile. The speed profile includes accelerating to the transfer speed and, after a period of time that depends on the length of the feed path, braking to the transport speed.

With the device according to the invention, the bag assembly can be further improved and automated to an even greater extent if the cover sheet target position and the target length of the cover sheets and optionally the valve sheet target position of valve sheets are calculated based on the recorded bag width and the predefined distance between successive bag bodies and cover sheets are cut to the target length and applied to the bag bodies based on this information when they have reached the cover sheet target position and optionally the valve sheets are applied to the bag bodies when they have reached the valve sheet target position.

With the device and the method according to the invention, it is possible to select the feed path so that a very small predefined distance is obtained between successive bag bodies, which is preferably no greater than 5 cm. Neighboring bags can also be arranged flush with one another.

An even better utilization of processing stations, such as a hot-air welding station, is achieved if the feed path is selected so that successive bag bodies overlap, with the overlap width preferably corresponding to one or two times the height of the triangular corner fold that is created when the bottom side flaps are folded in. In the latter case, at least in one of the successive bag bodies, a longitudinal section facing the other bag body, which has a width corresponding to the height of the corner fold, is folded over.

For reliable handling, the transfer device preferably has holding means for gripping, holding and releasing the bag bodies, whereby the holding means can be designed as mechanical grippers and/or vacuum suction cups. A control system controls the times at which the holding means grip and release the bag bodies. If at least two holding means are provided that can be moved independently of one another, it is possible to align misaligned bag bodies by means of different movements of the holding means using a suitable control system. Misalignments can be caused, for example, when the bag bodies are cut.

Fig. 1

zeigt eine schematische Darstellung einer Sackkonfektionieranlage gemäß den Prinzipien der Erfindung.

Fig. 2

zeigt eine perspektivische Darstellung einer Sackkonfektionieranlage gemäß einer Ausführungsform der Erfindung.

Fig. 3

bis Fig. 6 zeigen Draufsichten auf Sackkörper während ihres Transports auf der Transportvorrichtung, die die Abstände zwischen aufeinanderfolgenden Sackkörpern gemäß der Erfindung illustrieren.

Fig. 7

zeigt eine schematische Darstellung einer weiteren Ausführungsform einer Sackkonfektionieranlage gemäß den Prinzipien der Erfindung.

Fig. 8

zeigt schematisch eine Transportvorrichtung einer Sackkonfektionieranlage gemäß dem Stand der Technik.

The invention will now be described in more detail using embodiments with reference to the drawings.

Fig. 1

shows a schematic representation of a bag making plant according to the principles of the invention.

Fig. 2

shows a perspective view of a bag manufacturing system according to an embodiment of the invention.

Fig. 3

until Fig. 6 show plan views of bag bodies during their transport on the transport device, illustrating the distances between successive bag bodies according to the invention.

Fig. 7

shows a schematic representation of another embodiment of a bag making system according to the principles of the invention.

Fig. 8

shows schematically a transport device of a bag manufacturing plant according to the prior art.

With reference to Fig. 1 and Fig. 2 The principle of the device 1 according to the invention and of the method according to the invention for producing sacks from tubular sack bodies 10 is now explained and described using an exemplary embodiment. The device 1 comprises a transport device 2 which transports the sack bodies 10 lying flat across their longitudinal extent L at a transport speed V in a transport direction T. The sack bodies have a front side edge 11 and a rear side edge 12, between which the width b is measured. Guide rails 3 hold the sack bodies 10 in the correct position on the transport device. The sack bodies 10 are made from a fabric made of stretched plastic tapes or a nonwoven plastic material (e.g. plastic fleece) or a composite made from the fabric made of plastic tapes and the nonwoven plastic material or a plastic film connected to a net structure and are preferably provided with a coating made of a polymer. Composites can also comprise plastic films, paper layers or metal foils. Preferably, the coating comprises a layer of an OPP film, further printing layers, etc.

In the embodiment of Fig. 2 a hose 10a is fed from a storage device (not shown) or an inline hose production machine to a cross-cutting device 8, which cuts tubular bag bodies 10 from the hose 10a and feeds them to the transfer device 4 described in detail below.

During their transport on the transport device 2, the bag bodies 10 pass through processing stations with which at least one end region 13 of each bag body 10 is formed into a cross bottom and a cover sheet 19 is applied to the cross bottom. In the embodiment described, the processing stations described below are formed. In other embodiments of the invention, however, not all of these processing stations are implemented, or other processing stations (quality inspection, printing device, etc.) can also be provided.

The processing stations are in Fig. 1 for reasons of better clarity, only symbolically shown by arrows. A folding station 30 serves to fold the end regions 13 of the sack body 10 from the flat state upwards around the guide rails 3. A bottom opening station 40 serves to pull the two folded-up layers of the end regions 13 of the sack body 10 away from each other and to fold them over in opposite directions by 90° each, thereby creating an open bottom 17 which has two side flaps 15, 16, of which one side flap 16 is folded back by 180° onto the wall of the sack body 10. By folding over the side flaps 15, 16, a triangular corner fold 14 is created on the front and rear part of the open bottom 17. In a valve leaf insertion station 50, a valve leaf 18 is placed on the open bottom 17 of the sack body 10 and, if necessary, fixed by gluing or thermal welding. The final cross-bottom configuration is then produced in a bottom forming station 60 by folding in the bottom side flaps 15, 16, whereby the triangular folds 14 at the front and rear bottom end areas are reduced in size by folding in, but their triangular shape is retained. Since the side flaps 15, 16 are folded over at folding edges that are parallel to one another, the triangular folds have the shape of an isosceles triangle, the hypotenuse of which runs between the end points of the folding edges. The folded bottom side flaps 15, 16 are glued to one another, depending on the material of the bag body, or thermally welded if they overlap one another. However, there are also designs of bags in which the bottom side flaps 15, 16 do not overlap one another. In the embodiment shown, a cover sheet application station 70 for applying a bottom cover sheet 19 to the folded bottom side flaps 15, 16 and a hot air welding station 80 for fixing the bottom cover sheet 19 to the folded bottom side flaps 15, 16 are also provided. The cover sheet application station 70 and the welding station 80 can be integrated into one another. As an alternative to the welding station 80, an adhesive station can also be provided.

According to the invention, the device 1 has a transfer device 4 to which the bag bodies 10 are fed either transversely or longitudinally. The transfer device 4 transfers the fed bag bodies 10 in a transverse arrangement to the transport device 2 by means of a movement in the transport direction T. According to the invention, the transfer device 4 moves bag bodies 10 to be transported in relation to bag bodies conveyed at transport speed V by a feed distance Δy in the transport direction T and then transfers them to the transport device 2, wherein the transfer device 4 moves the bag bodies 10 in the transport direction T at least in sections at a transfer speed U which is greater than the transport speed V. While the bag bodies 10 are at a distance y1 from one another when fed to the transfer device 4 and move at the transport speed T in the transport direction, they have a reduced distance y2 from each other after being transferred to the transport device 2, which is caused by the movement by the feed distance Δy. The feed distance Δy can therefore be calculated as follows: $$\mathrm{feed\; path}\mathrm{\Delta }\mathrm{y}=\mathrm{sack\; body\; distance}\mathrm{y1}-\mathrm{sack\; body\; distance}\mathrm{y2}$$

By reducing the distance between adjacent bag bodies from y1 to y2 between the tubular bag bodies during transport, the original length of the repeat x1 is shortened by the feed distance Δy to the repeat length x2. Thus, the throughput of bag bodies 10 through the device 1 can be increased while maintaining the same transport speed T.

As in Fig. 2 . As shown, the transfer device 4 can have holding means 4b for gripping, holding and releasing the bag bodies. In this exemplary embodiment, the holding means 4b are designed as mechanical grippers which are attached to endless belts 4a running around pulleys 4c, 4d. One of the pulleys 4c is driven by a drive 7 which is (automatically) controlled by a controller 6 which can also control the holding means 4b. As an alternative to grippers, the holding means 4b can also be designed as vacuum suction cups. The feed distance Δy can be calculated and changed using the controller 6. Furthermore, the controller 6 can control the speed of the drive 7 and controls the times at which the holding means 4b grip and release the bag bodies 10.

Since the distances y1, y2 between the bag bodies 10 and the bottom cover sheets 19 are varied according to the invention, the processing stations 30, 40, 50, 60, 70, 80 provided in the device 1 are also equipped with individual drives, switches and actuators - e.g. controlled by the control 6 - in order to be able to react to the variable bag distances. For reasons of clarity, the connection of the control 6 with the transfer device 4 and the processing stations 30, 40, 50, 60, 70, 80 is shown in the Figures 1 and 2 not shown. This connection is either a point-to-point line (serial or parallel) or a network connection.

The control 6 contains a computer with which the feed distance Δy can be calculated as a function of the width (b) of the bag bodies 10 in such a way that a predefined distance y2 between successive bag bodies 10, 10 or between the cover sheets of successive bag bodies is obtained (distance y3, see Fig. 1 ). The controller 6 controls the transfer device 4 according to the calculated feed distance Δy.

For automatic operation of the device 1 according to the invention, a sensor 5 is provided for detecting the width b of the bag body 10. The sensor 5 sends the detected width b to the control 6. The sensor 5 can, for example, be camera-supported or detect the width b by means of light barriers.

In contrast to the prior art, in which the repeat is kept constant, according to the invention the feed distance Δy is varied depending on the bag body width b and thus the length of the repeat is changed. The smaller the bag body width b, the greater the feed distance Δy by which the bag body is advanced. The distance y2 between the bag bodies 10 can thus be kept constant even with different bag body widths b.

For gentle handling of the bag bodies and precise picking up and transferring, the controller 6 controls the speed at which the transfer device 4 moves the bag bodies in the transport direction T according to a speed profile. This speed profile includes accelerating the picked up bag bodies, which are fed to the transfer device 4 at a speed between 0 and the transport speed V, to the transfer speed U and, after a period of time dependent on the length of the feed path Δy, braking to the transport speed V. Furthermore, the controller 6 can calculate the target position and target length of the cover sheet 19 and optionally the target position of a valve sheet 18 based on the recorded bag width b and the predefined distance y2 between successive bag bodies and use this information to control the cover sheet application station 70 so that it cuts a cover sheet 19 according to the target length and applies it to the bag body 10 when it has reached the target position. In a similar way, the control 6 controls the valve sheet insertion station 50 so that it applies a valve sheet 18 to the bag body 10 when it has reached the desired position. It should be mentioned that the length of the cover sheets is mathematically determined from the dimension that determines the thickness of the bag by which the bottom side flaps 15, 16 are folded in, since this dimension specifies the length of the fold edges, thus also the length of the cross bottom and thus the length of the cover sheet 19.

The transfer device 4 according to the invention can also react to width fluctuations of the supplied bag bodies 10, and as a result the accuracy at the following processing stations can be increased and thus the quality of the bags can be optimized.

The smaller distance between the bag bodies 10 also increases the efficiency of a hot-air welding device 80 for fixing the bottom cover sheets 19, since the idle time and the energy loss due to unused heat is minimized.

In many applications, the feed distance Δy is chosen so that a predefined distance y2 between consecutive bag bodies is between 0 (ie the bag bodies are flush, see Fig. 3 ) and 5 cm (see Fig. 4 ) results. The smaller the distance between the bag bodies, the shorter the time in which, for example, the hot air welding station 80 releases its thermal energy unused into the environment. In the Fig. 5 In the embodiment shown, this distance is shortened even further by arranging adjacent bag bodies 10, 10 so that they overlap to the extent of the height h of the triangular covers. Mathematically speaking, this results in a distance of -h between adjacent bag bodies. In order to bring the distance between the cover sheets 19 of adjacent bag bodies 10, 10 to 0, ie to arrange them flush, in the extreme case (see Fig. 6 ) the overlap width of adjacent bag bodies 10, 10 can be selected as twice the height h of the triangular corner fold, resulting in a distance of -2h. For practical implementation, however, it is necessary to fold over a longitudinal section facing the other bag body, which has a width h, in at least one of the consecutive bag bodies.

However, it should be noted that the extremely reduced distances between adjacent bag bodies 10, 10, as in Fig. 5 and Fig. 6 shown, are not suitable for every subsequent processing station. For example, if the bag bodies 10 are transferred from the transfer station 4 to Fig. 1 are pushed together at the transfer station to such an extent that they overlap, folding the end regions 13 upwards at the folding station 30 and opening the end regions 13 at the bottom opening station 40 would not be possible. On the other hand, extremely narrow distances between the adjacent bag bodies also have the advantages described above. The present invention therefore also provides that the distances between adjacent bag bodies 10, 10 are reduced in several stages by arranging several transfer devices 4 according to the invention along the transport device 2. For example, a second transfer station 4 can be arranged after the bottom opening station 40, with which the distance y2 between adjacent bag bodies 10, 10 is reduced to -h. In Fig. 7 is shown schematically an embodiment of the device according to the invention for producing bags from tubular bag bodies, which is similar to that of Fig. 1 corresponds, with the difference that in the embodiment of Fig. 7 the second transfer station 4 is arranged directly in front of the cover sheet application station 70, whereby adjacent bag bodies 10, 10 can even be pushed together to a distance of y2=-2h. Alternatively, the distance can also be reduced step by step with a second transfer station after the bottom opening station 40 and a third transfer station 4 directly in front of the cover sheet application station 70.

Furthermore, it is also possible for only one transfer station, which is located directly after the bottom opening station 40 or further back along the transport device, to reduce the distances between the adjacent bag bodies. This means that the bottom opening station 40 has "more time" to open the bottoms and at the same time the thermal energy of the welding station 80 is optimally utilized.

Because the distances between the bag bodies and the bottom cover sheets are varied, the processing stations such as bottom openers, valve inserters and

Top sheet applicators can be equipped with individual drives in order to be able to react to the variable bag spacing.

Claims (13)

1. A device (1) for producing bags from tubular bag bodies (10), wherein the bag bodies are preferably made from a fabric of plastic strips or a nonwoven plastic material (e.g., plastic nonwoven fabric) or a composite of the fabric made of plastic strips and the nonwoven plastic material or a plastic film connected by a web structure, wherein the material is optionally coated at least on one side by a plastic layer and/or at least one plastic film, e.g., an OPP film,

   having at least one transport device (2), which transports the bag bodies in a flat manner transversely to the longitudinal extent (L) thereof at a transport rate (V) in a transporting direction (T), wherein the bag bodies, while being transported, pass through processing stations (30, 40, 50, 60, 70, 80), by way of which at least one end region (13) of each bag body is formed into a cross bottom and optionally a cover sheet (19) is applied to the cross bottom,

   characterized by at least one transfer device (4), which moves the bag bodies (10) to be transported by the transport device, with respect to bag bodies conveyed at a transport rate (V), by a feeding distance (Δy) in the transporting direction (T) and then transfers them to the transport device (2), wherein the transfer device (4) moves the bag bodies in the transporting direction (T) at least in some sections at a transfer rate (U), which is higher than the transport rate (V), and characterized by a controller (6), which calculates the feeding distance (Δy) as a function of the width (b) of the bag bodies such that there is produced a predefined distance (y2, y3) between successive bag bodies or between the cover sheets (19) of successive bag bodies (10), and which controls the transfer device (4) according to the calculated feeding distance (Δy), wherein the controller (6) controls the rate, at which the transfer device (4) moves the bag bodies in the transporting direction (T), according to a rate profile, which comprises accelerating to the transfer rate (U) and, after a period of time as a function of the length of the feeding distance (Δy), decelerating to the transport rate (V).
2. A device according to claim 1, characterized in that the transfer device (4) has holding means (4b) for grasping, holding and releasing the bag bodies, wherein the holding means preferably comprise mechanical graspers and/or vacuum suction means.
3. A device according to claim 1 or 2, characterized by a sensor (5) for detecting the width (b) of the bag bodies, which transmits the detected width to the controller (6).
4. A device according to the claims 1, 2 and 3, characterized in that the controller (6) controls the points of time at which the holding means (4b) grasp and release the bag bodies.
5. A device according to any of claims 3 or 4, characterized in that the controller (6), on the basis of the detected bag width (b) and the predefined distance (y2) of successive bag bodies, calculates the desired position of the cover sheet and the desired length of the cover sheet (19) as well as optionally the desired position of the valve sheet of a valve sheet (18) and controls, on the basis of this information, a processing station for cover sheet applying (70) such that it cuts a cover sheet (19) according to the desired length and applies it to the bag body, if it has reached the desired position of the cover sheet, and optionally a processing station for valve sheet inserting (50) such that it applies a valve sheet (18) to the bag body, if it has reached the desired position of the valve sheet.
6. A device according to any of the preceding claims, characterized in that the feeding distance (Δy) is selected such that there is produced a predefined distance (y2) of between 0 and 5 cm between successive bag bodies.
7. A device according to any of claims 1 to 5, characterized in that the feeding distance (Δy) is selected such that successive bag bodies overlap one another, wherein the overlapping width preferably corresponds to once or twice the height (h) of the triangular corner fold (14), which is produced when the bottom side flaps (15, 16) are folded over, wherein in the latter case, at least in one of the successive bag bodies, a longitudinal portion (10b) facing the other bag body, which has a width corresponding to the height (h) of the corner fold, is folder over.
8. A device according to any of claims 2 to 7, characterized in that there are provided at least two holding means (4b), which may be moved independently from one another.
9. A method for producing bags from tubular bag bodies (10), wherein the bag bodies are preferably made from a fabric of plastic strips or a nonwoven plastic material (e.g., plastic nonwoven fabric) or a composite of the fabric made of plastic strips and the nonwoven plastic material or a plastic film connected by a web structure, wherein the material is optionally coated at least on one side by a plastic layer and/or at least one plastic film, e.g., an OPP film,

   wherein the bag bodies (10) are transported in a flat manner transversely to the longitudinal extent (L) thereof at a transport rate (V) in a transporting direction (T), wherein in the bag bodies, while being transported, at least one end region (13) is formed into a cross bottom and optionally a cover sheet (19) is applied to the cross bottom,

   characterized in that the bag bodies (10) to be transported are moved, with respect to bag bodies conveyed at a transport rate (V), by a feeding distance (Δy) in the transporting direction (T) and then at a transport rate (V), wherein the movement of the bag bodies on the feeding distance (Δy) is carried out at least in some sections at a transfer rate (U), which is higher than the transfer rate (V), and characterized in that the feeding distance (Δy) is calculated as a function of the width (b) of the bag bodies such that there is produced a predefined distance (y2, y3) between successive bag bodies (10) or between the cover sheets (19) of successive bag bodies and such that the movement of the bag bodies is controlled according to the calculated feeding distance (Δy), wherein the rate, at which the bag bodies are moved on the feeding distance (Δy), is controlled according to a rate profile, which comprises accelerating to the transfer rate (U) and, after a period of time as a function of the length of the feeding distance (Δy), decelerating to the transport rate (V).
10. A method according to claim 9, characterized in that the width (b) of the bag bodies is detected using a sensor (5).
11. A method according to claim 10, characterized in that, by way of the detected bag width (b) and the predefined distance (y2) of successive bag bodies, the desired position of the cover sheet and the desired length of the cover sheets (19) as well as optionally the desired position of the valve sheet of valve sheets (18) are calculated and that, by way of this information, cover sheets (19) are cut according to the desired length and then applied to the bag bodies (10), if they have reached the desired position of the cover sheet, and optionally the valve sheets (18) are applied to the bag bodies, if they have reached the desired position of the valve sheet.
12. A method according to any of claims 9 to 11, characterized in that the feeding distance (Δy) is selected such that there is produced a predefined distance (y2) of between 0 and 5 cm between successive bag bodies.
13. A method according to any of claims 9 to 11, characterized in that the feeding distance (Δy) is selected such that the successive bag bodies overlap one another, wherein the overlapping width preferably corresponds to once or twice the height (h) of the triangular corner fold (14), which is produced when the body side flaps (15, 16) are folded over, wherein in the latter case, at least in one of the successive bag bodies, a longitudinal portion (10b) facing the other bag body, which has a width corresponding to the height (h) of the corner fold, is folded over.

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