WO2016155748A1

WO2016155748A1 - Bag web and method for making such a bag web

Info

Publication number: WO2016155748A1
Application number: PCT/DK2016/050094
Authority: WO
Inventors: Henrik Pape
Original assignee: Schur Technology A/S
Priority date: 2015-04-01
Filing date: 2016-04-01
Publication date: 2016-10-06
Also published as: DK201570194A1; EP3277595A1; EP3277595A4; DK178614B1

Abstract

There is disclosed a bag web with a continuous web of laterally folded bag items which are formed of two superposed film webs forming opposing front and back sides of a bag item. The folded parts of the first film web are disposed between the front and back sides of the bag item for forming at least one first folded side in the bag item, the first folded side formed of material from the first film web. Hereby insertion of separate pieces for the formation of side folds is avoided.

Description

BAG WEB AND METHOD FOR MAKING SUCH A BAG WEB

Field of the Invention

The present invention concerns a bag web with a continuous web of laterally folded bag items, which are formed by first and second superposed film webs forming opposing front and back sides of a bag item.

The invention further concerns a method for producing a bag web with a continuous web of laterally folded bag items, which are formed of a first and a second superposed film web forming opposing front and back sides of a bag item, and wherein the folded parts of the first film web are disposed between the front and back sides of the bag item for forming folded sides in the bag item.

Background of the Invention

Bag webs for making bags of the type with side and bottom sections connected by the flat sides are known. They will usually be folded sides and/or bottoms. This bag type is also known as gusset bags or bags with cross bottom, or known as side-gusseted bags where short sides are formed between the flat sides of the bag. Side sections and bottom sections that are welded to the large flat sides of the bag are therefore provided in these bags. Such bags are formed in webs with a series of juxtaposed bag items made of two superposed film webs. Between the two film webs folded film pieces are placed for forming the folded side sections of the bag, and possibly bottom sections as well. This web is cut up for forming individual bags. The bags may be provided with a zipper. The bags are filled subsequently by moving the individual bags to a filling station at which filling is performed. An example of such a web and making thereof are described in EP 1 250 999.

For many years there has been a wish for making folded bags in a way so as to increase the rate of filling and for producing the bags with side folds and possibly bottom folds cheaper. Object of the Invention

It is an object of the invention to indicate a bag web and a method for making such a bag web wherein bag items appear as folded bags made without the need for separate film pieces for the formation of the folded side sections of the bag. Furthermore, it is an object to indicate such a continuous web of bag items that can be conveyed through a filling station, thereby yielding a high rate of filling.

Description of the Invention

According to the present invention, this object is achieved by a bag web of the kind mentioned in the introduction, which is peculiar in that the folded parts of the first film web are disposed between the front and back sides of the bag item for forming at least one first folded side in the bag item, the first folded side formed of material from the first film web.

The method according to the invention is peculiar by including steps, wherein:

A - a first and a second superposed film web is conveyed from a film web storage;

B - a part of the first film web is folded as at least one folding blade is displaced in a direction transversely to the conveying direction of the first film web in direction towards the second film web, hereby establishing a first folding along a first folding line at the edge of the folding blade;

C - folding the folded part down towards the first film web about a second folding line between the folded part and the first film web;

D - fixing the folded part in its position in contact with the first film web;

E - placing the second film web in a superposed position over the first film web; F - welding the two superposed film webs together with transverse weldings at the folded parts such that the folded parts are disposed in the bag items between front and back sides of the latter;

G - welding the two superposed film webs together at least along a longitudinal side edge at a bottom of the bag items. According to an embodiment, the bag web may be peculiar in that the folded parts of the first film web also form a second folded side of the bag item. By a method and a bag web according to the invention it is therefore possible to form the side folds of the bags from the folded parts of the first film web. The need for using separate film pieces for providing the folded side section of the bag is hereby avoided. A substantial simplification of the design of a bag web and a method of producing such a bag web are hereby achieved.

According to a further embodiment, the bag web may be peculiar in that the two superposed film webs have the same width, and that the folded parts extend across the entire width of the film webs.

By this embodiment it is possible to produce bags having a height corresponding to the width of the film webs, and wherein the side edges of the bag are provided with foldings extending along the entire height of the bag. According to a further embodiment, the bag web may be peculiar in that the folded parts are attached to the first film web from where the folded parts are unfolded by spot welds along folding lines between the folded part and the associated film web.

By attaching the folded parts and the film web from where they are unfolded, a fixing of the foldings about the folding lines is achieved. This is expedient when handling the bag web. In the finished bag web it will be possible to provide a welding along the folding lines between the folded part and the associated film web. Hereby is achieved a greater stiffness in the formed bag. According to a further embodiment, the bag web may be peculiar in that the superposed film webs are made of multi-layered films, where at least one outermost layer of the first and second film webs facing the other film web is made of a weldable plastic material, preferably PE or PP, and where at least one outermost layer of the first and second film webs facing away from the other film web is made of a non- weldable plastic material, preferably PET, OPA or OPP.

By using multi-layered films it is possible to perform welding together of the surfaces that are wanted welded together, and to avoid the welding together of the outermost layers facing away from each other. It will hereby be possible to perform welding at the folding lines between the folded part and the associated film web, even if the heat is transmitted through the folded part. The edge areas along the folding lines in the edge area of the folded part will thus not be welded together as the materials placed in contact with each other will be made of non-weldable plastic material.

According to a further embodiment, the bag web may be peculiar in a zipper is provided on the first or on the second film web, the zipper including interacting zipper parts, and that in connection with the zipper and in parallel therewith a weakening line or perforation is provided which is easily torn up for establishing an access opening to the interior of a finished bag, the access opening capable of being opened and closed by means of the zipper.

A zipper in this bag may therefore be provided in a technically simple way, and an access opening for the contents of the bag will be formed in one of the flat sides of the bag. The advantage of this bag is that it is easy to make such that it is entirely airtight.

According to a further embodiment, the bag web is peculiar in that interacting zipper parts of a zipper are provided opposite each other on the film webs forming opposing front and back sides in the film web of the bag, and that these interacting zipper parts are provided in parallel with the opening edges in immediate vicinity thereof for establishing an access opening to the interior of a finished bag, the access opening capable of being opened and closed by means of the zipper.

By this disposition of the zipper, the access opening will be formed at the top of the bag between the peripheral areas of the two flat sides. This provides a large access opening.

According to a further embodiment, the bag web may be peculiar in that the bag web along its opening edges includes peripheral strip areas prepared with a series of holes or corresponding star perforations intended for guide connection with guide means, which are arranged for retaining and guiding peripheral areas at the opposing bag opening edges along a conveyor path through a filling station, the bag web being of the type consisting of a contiguous series of bag items separated by a number of slits that extend from a bottom edge of the web up to a point below an upper edge of the web.

By such a bag web it will be possible to establish filling with known equipment. Such equipment is, for example, described in EP 1087890 and EP 1451069. Both documents describe holing pegs serving to engage the holes in the peripheral strip areas. A secure carrying and advancing engagement is hereby ensured. These bag webs have only been described as flat bags. By the present invention it is thus possible to use prior art filling equipment in combination with bag webs where the side folds are formed in a very simple way compared with the bag webs where side folds are formed by separate folded film pieces. It is thus possible to use the folded bags and to increase the filling rate thereof compared with previous individual filling as described in EP 1250999.

According to a further embodiment, the bag web may be peculiar in that the folded parts extend across part of the width of the film webs, and that material located in the edge area of the bag webs opposite the folded parts and at bag opening edges is removed over a distance in the length of the film webs corresponding to the length of the film web used for forming the folded parts, such that the edge area appears largely unbroken and without folding. By such a design, a bag web provided with peripheral strip areas can be folded in such a way that the edge area appears unbroken and without folding. By removing part of the bag webs in the edge area at a position above the folded parts, a bag web having peripheral strip areas that may be used for establishing the guide connection by the guiding means can be established in a simple way.

According to a further embodiment, the method may be peculiar in that

- step C includes displacing the folded part towards the first film web such that half of the folded part at either side of the first folding line is folded to each their side about each of the two other folding lines between the folded part and the first film web, hereby effecting a folding about third folding lines of each half of the folded part.

By this embodiment is achieved a simple formation of a fold as there is only need for one folding blade. When the folding blade has displaced the folded part with desired height, there is provided an engagement with a support. When the support is moved down towards the first bag web simultaneously with withdrawal of the folding blade, third folding lines will be formed at either side of the first folding line at the middle between the first folding line and the other folding lines provided between the folded part and the first film web. These second and third folding lines can be secured if the support plate pressing the folded part down against the first film web is heated. Also, the support plate can be provided with heating pins that are moved towards the edge areas along the first and/or other folding lines such that spot welds are established along the folding lines so that the folded part stays fixed with the desired folding.

After fixing the folded parts on the first film web, the second film web is moved into a superposed position relative to the first film web, after which is performed the required weldings for formation of the bag items. According to a further embodiment, the method may be peculiar in that

- step B includes folding by two parallel folding blades that are both displaced transversely to the conveying direction of the first film web in direction towards the second film web, hereby establishing two parallel first foldings; and that

- step C includes folding the folded parts to each their side about the other folding lines between the folded part and the first film web.

By this embodiment are used two parallel folding blades. Hereby is formed a folded part at each of the folding blades. The folding blades are moved to their outer position where the folded parts are established with desired size. The folding blades can be retracted at the same time as a support is moved against the folding so that the folded parts are folded to each their side. Particular certainty that the folded parts are folded about the other folding lines located between the folded part and the first film web is hereby achieved. The third folding line will hereby be established at the outer edge on the folding blades. By this embodiment a first folding line will therefore not appear. By this embodiment different sizes of the folded parts can be applied, if so desired.

When the folded parts have been moved to each their side about the other folding lines, a spot weld can be established, as described above.

It is noted that the support can be provided in the form of a plate disposed in parallel with the film web and which is moved translationally towards and away from the film web in a movement coordinated with the folding blades.

Alternatively, the support can be provided by an endless belt which is pivotably suspended at a position above the folding blade or blades.

By a support in the form of an endless belt it will be possible to move the second film web along the endless belt such that it is brought to engage the folded parts during their folding down towards the first film web. The process of forming the bag webs can hereby be established more rapidly.

After superposing the first and second film webs, which have been brought together, they are moved through welding equipment establishing welds for forming the bag items.

By the formation of the bag items is noted that the required weldings can be established for the formation of the finished bag item.

In a finished bag item, a bottom can optionally be formed by a bent part of one of the bag webs, or by placing a separate folded bottom section that is welded to the flat sides of the bag item. According to a further embodiment, the method may be peculiar in that

alternatively, the method may imply folding of parts of both film webs being performed in steps, wherein:

- step B includes folding a part of the first film web by displacing one folding blade in a direction transversely to the conveying direction of the first film web in direction towards the second film web, hereby establishing a first folding along a first folding line at the edge of the folding blade, and folding a part of the second film web by displacing an additional folding blade in a direction transversely to the conveying direction of the second film web in direction towards the first film web, hereby establishing a first folding along a first folding line at the edge of the additional folding blade; and that

- step C includes folding each the folded parts down against the associated film web about the second folding line between the folded part and the associated film web; and that

- step D includes fixing the folded parts in their position in contact with the associated film web.

By this method, the side folds of the bag items can be made by folded parts of the first film web and the second film web. The folded parts can thus be displaced in direction towards the opposite film web. By this embodiment is achieved the advantage that the same conveying speed can be applied to both film webs as equally large folded parts are established in each of the two film webs. The two film webs will hereby appear with the same length both before and after the folding operation. According to a further embodiment, the method may be peculiar in that the method includes choosing film webs made of multi-layered films, where at least one outermost layer of the first and second film webs facing the other film web is made of a weldable plastic material, preferably PE or PP, and where at least one outermost layer of the first and second film webs facing away from the other film web is made of a non- weldable plastic material, preferably PET, OPA or OPP.

By using multi-layered films it is possible to perform welding together of the surfaces wanted to be welded together, and to avoid the welding together of the outermost layers facing away from each other. It will hereby be possible to perform welding at the folding lines between the folded part and the associated film web, even if the heat is transmitted through the folded part. The edge areas along the folding lines in the edge area of the folded part will thus not be welded together as the materials placed in contact with each other will be made of non- weldable plastic material. According to a further embodiment, the method may be peculiar in that

- step B includes retaining the first folding along the first folding line at the edge of the folding tool by squeezing the film web between the edge of the folding tool and a support.

As mentioned above, the folding blade may interact with a support. The support can be pressed against the folding blade such that the folded part is secured. Hereby is achieved particular certainty of establishment of a folding at a desired position. It is noted that the support can be moved down against the first film web so that the folding blade immediately squeezes the film web against the support and maintains such a securing during the movement of the folding blade. Alternatively, the folding blade and the support are first brought into squeezing contact when the folding blade has reached its extreme position. In both cases, support and folding blade will be moved at the same time in direction against the first film web for folding around the other folding edges between the folded parts and the first film web.

According to a further embodiment, the method may be peculiar in that

- step B includes using a pivotable or displaceable support such that the first folding along the first folding line at the edge of the folding blade is retained from the commencing formation of the folding and onwards during the subsequent step C.

By using the pivoting or displaceable support, the securing can occur from the commencing formation of the folding and during the whole folding action. As mentioned above, this is particularly advantageous for establishing a secure position of the folding and a certain size of the folding.

According to a further embodiment, the method may be peculiar in that

- step D includes fixing of the folded part being performed by means of welding means provided in the support.

By performing a fixing of the folded parts, a more certain positioning of the folding is achieved before subsequently being brought to engage between two superposed film webs and the subsequent welding together for the formation of a bag. Fixing of the folded parts will preferably be by spot weldings. Alternatively, along the other folding lines and close to the first folding line there may be established a continuous welding between the folded part and the first web at one side and the folded part and the second bag web at the other side. The folded part hereby appears with rigid edges at the joint with the large flat sides of the bag.

Correspondingly, by a bottom part welding to the long sides of the bag will also be used for establishing a rigid bag bottom. According to a further embodiment, step A may include conveying the first and possibly also a second superposed film web from a film web storage by using a first set of rollers before the folding step and a second set of rollers after the folding step, wherein the rollers are squeezing the associated film web and are applied for conveying the film web, in that the first and second pair of rollers have differentiated rotation during the folding step.

By using different sets of rollers before and after the folding step, respectively, it will be possible to operate with a differentiated and controlled conveying speed, ensuring that the two film webs are conveyed at correct speed in relation to the conveying speed for the bag web, which is formed after the folding and welding.

According to a further embodiment, the method may be peculiar in that

- step F is performed at a position after the second set of rollers. By welding the two superposed film webs with transverse weldings after the second set of rollers, a uniform conveying speed is established for both of the superposed film webs.

According to a further embodiment, the method may be peculiar in that the method includes an additional step H where between succeeding bag items a transverse cutting is performed, extending from a bottom edge of the film webs up to a point below a top edge of the web for the formation of a contiguous series of bag items divided by a number of slits. By such a cutting is established a bag web which is contiguous along an edge region. Such a bag web is suited for use in traditional filling equipment.

According to a further embodiment, the method may be peculiar in that along its opening edges, the bag web includes peripheral strip areas prepared with a series of holes or corresponding star perforations that are intended for guide connection with guide means, which are arranged for retaining and guiding peripheral areas at the opposing bag opening edges along a conveyor path through a filling station. By performing the invention, the constructional details of bag web and method known from the two European patents EP 1087890 and EP 1451069, the contents of which are hereby incorporated by reference, can be applied.

By performing the invention, the constructional details for making the bag items of the bag web known from the European patens EP 1250999, the contents of which is hereby incorporated by reference, can be applied as well.

By providing peripheral strip areas prepared with holes the method will be suited for making a bag web that can be used in prior art filling equipment, where guiding means are provided, engaging the holes of the peripheral strip areas in order to establish a secure holding and guiding of the bag web through a filling station.

Description of the Drawing

The invention will now be explained in further detail with reference to the accompanying schematic drawing, wherein

Fig. 1 is a perspective view for illustrating a technique known from EP 1087890 with a bag web including a series of bag items that can be designed according to the present invention;

Fig. 2 is a perspective partial view of a bag web according to the invention with a series of bag items provided with a zipper, and with the bag items in partly open condition;

Fig. 3 is a perspective partial view of a bag web according to the invention with bag items provided with a different type of zipper, and shown in almost completely open condition; Fig. 4 shows a partial perspective view of steps of the method according to the invention;

Fig. 5 shows a schematic view for illustrating the method according to the invention in which is used a folding blade and a support plate for forming the folded parts in the first film web;

Figs. 6-8 show three different schematic views for illustrating steps of the method, where the folding is formed and fixed;

Figs. 9-16 show partial views for illustrating steps of the method according to the invention;

Fig. 17 are schematic drawings of a method according to the invention by which is used a folding blade for forming the folded parts from a first film web;

Fig. 18 shows a partial view of steps of a further embodiment of the method according to the invention;

Fig. 19 show schematic drawings corresponding to Fig. 17 of another embodiment of steps of the method according to the invention for forming the folded parts by applying a folding blade;

Fig. 20 shows a schematic drawing corresponding to Fig. 19 of another embodiment of steps of the method according to the invention where two parallel folding blades are used for forming the folded parts of the first film web;

Fig. 21 shows a schematic drawing of a film web according to the invention with a series of bag items, where part of a peripheral area provided with holes or perforations is removed; and

Fig. 22 shows an enlarged sectional view of the folded parts after welding the two film webs together. Detailed Description of Embodiments of the Invention

In the explanation of the Figures, identical or corresponding elements will be provided with the same designations in different Figures. Therefore, no explanation of all details will be given in connection with each single Figure/embodiment.

Fig. 1 illustrates a principle of designing a bag web 4 with peripheral areas at the outer opposite bag opening edges and guide means adapted to retain and guide the peripheral areas at the opposing bag opening edges so that the bag web can be conveyed through a filling apparatus 36 as a continuous web. In this Figure, bag items 12 are shown in simplified form, and the side foldings of the bags are therefore not clearly visible.

In Fig. 1 is shown that from a supply roll 2 a bag web in the form of a film material web 4 can be unrolled, consisting of a double film folded about a bottom edge 6 and joined along the upper edge by a simple welding 8, without foldings or thickenings of any kind. Therefore, it may also be a tubular film. In the web appears a series of slits 10 that extend from the bottom edge 6 up to a point below the top edge 8 so that the web appears with mutually separate bag items 12, the side edges of which include side folds and which are closed by weldings 14. Right over the top of the slits 10, the double web is cut by respective horizontal lines 16 extending shortly out at either side of the associated slits 10.

Between the top edge 8 and the cutting lines 16, the peripheral areas 40 of the web are penetrated by a single row of perforations 18.

This previously made web 4, which instead of being rolled up better can appear in a supply box in zigzag folded shape, is unwound by a filling unit on a support bar or rail 20 extending from a fixed support member 22 of the unit and serving as simple support for the closed top edge 8 of the web 4.

At a short distance in front of the carrier member 22, the support bar 20 has an upwardly projecting cutter member 24 which by advancing the web will continuously cut the top edge of the latter, and thereafter is arranged a continuing carrier system consisting of opposing parallel carrier chains 26 that are made with upright holding studs 28 for engaging holes 18 in respective top parts of the web that are laid out at both sides, and by a pressing roller 30 which after threading the film web in provides for drawing down the said unfolded top edge areas of the web 4 towards the firmly supported carrier chains 26 for horizontal bearing against the top sides of the latter, and thereby under pivoting down of the holes 18 in such a way that the holes 18 are pivoted down and engage over the chain studs 18. The pressing roller 30 has turned-in grooves 32 for enabling free passage of the outer end parts of the chain studs 28, and in these grooves there are embedded transversely positioned studs (not shown) which like a cogwheel can interact with the chain studs 28 for automatic synchronous driving of the pressing roller 30.

The opposing upper edge parts of the web 4 will then be securely anchored to the carrier studs 28, and the carrier chains may then be guided through a desired course for successive opening of the bag items as indicated by 34, whereby they can be filled by a filling apparatus 36 disposed above the open bag item and for closing the items after filling thereof. The filling apparatus 36 is provided with a filling unit in the form of a filling nozzle 38. It is considered unnecessary to indicate this in more detail. However, it is to be noted that the studs 28 are provided in the neutral lines of the chains such that the bag item web is not subjected to tensioning or slacking in passages with changes of direction.

The filled bags are released from the rest of the web, which is rolled up as excess, by welded closing of the bag items immediately under the top of the slits 10 and a possible subsequent cutting off. It is to be mentioned that on the fixed carrier member 22 there is preferably provided a guide body with a double-wing ploughshare shape that actively produces or initiates the shown unfolding of the perforated web periphery areas, whereby an improved security can be achieved with regard to the important function that is the guiding of the holes down over the studs 28.

Fig. 2 shows a detail of a second embodiment of a bag web according to the invention with a number of bag items 12 in a position where studs 28 of the carrier chains 26 are passed through apertures 48 in peripheral strip areas 50. The bag items are here provided with a zipper 58. The peripheral strip areas 50 are thus provided at bag opening edges 52 such that the peripheral strip areas 50 are contiguous with the bag items 12.

The bag items are formed with two opposing flat sides 54, and between these there are provided folded side sections 46. Moreover, bottom sections 56 are provided between the flat sides 54.

In the shown embodiment, a zipper 58 is provided in that a first zipper part 60 is provided at one flat side and a second zipper part 62 is provided at the opposing flat side of the bag item. In this embodiment, the zipper 58 is shown at a position immediately under the bag opening edges such that the bag can be opened across its entire width. Fig. 3 shows a detail of a bag web corresponding to the bag web shown in Fig. 2. In this bag web, however, the zipper 58' is provided in one of the flat sides 54 of the bag item 12. In immediate connection with the zipper 58' there is provided a perforation 64 defining an access opening to the bag. This access opening will thus be provided in the flat side 54.

The bag items 12 have side edges that are formed by means of folded side sections 46. This is true for the bag items shown in Figures 2 and 3. The side sections 46 are fastened to the flat sides 54 via weldings 66. As seen on Figures, the side sections 46 are provided with a folding along a line 68.

The bottom sections 56 can be provided as separate film sections or provided by bending the edge areas of one of the film webs used for making the flat sides 54 in the bag items. Figs. 4 and 5 shows the various steps at the making of the bag web 4 illustrated in Fig. 1. Fig. 4 is a partial detail of the process shown in Fig. 5. In Figs. 4 and 5 appears a first film web 70' on which is superposed a second film web 70. The first film web 70' is provided with folded parts that will constitute folded side sections 46 in a finished bag. These folded parts 46 will thus be disposed between the two film webs such that in a bag item they will be located between a front and a back side of a bag item.

The first film web 70' is rolled off a supply roll 96 rotated in the direction of arrow 98. The film web 70' is passed around a pair of rollers 100 between which is provided a roller 102 that can be moved up and down as indicated by arrow 104. Hereby tensioning of the film web 70' is ensured. A first pair of rollers 106 is disposed in front of a roller blade 108, and a second pair of rollers 110 is disposed below the roller blade 108. The two roller pairs 106, 110 serve to advance the film web 70' . As folding by the action of the roller blade occurs between the two pairs of rollers, they will operate at different conveying speeds. The pair of rollers 110 will thus run at a speed corresponding to the conveying speed of the finished bag after the formation of foldings that constitute the folded side sections in the finished bag item. The pair of rollers 106 runs at a higher speed such that they at a given time can convey a length corresponding to the bag width and the length of the folded side sections.

The folding blade 108 is displaced between two support plates 112 in the first film web 70' . The folding blade interacts by bearing against a support plate 114 for forming a first folding 115 at a first folding line at the edge 118 of the folding blade 108. The folding blade 108 and the support plate 114 can be displaced synchronously, as indicated by arrows 116, in order to squeeze the first film web 70' between the support plate 114 and the edge 118 of the folding blade.

A detailed elaboration of the folding will be provided later.

After formation of the foldings, the second film web 70 is moved down over and superposed the first film web 70' . The superposed film webs are then moved through a welding station 120. A transverse welding 66 and possible additional weldings in longitudinal direction of the bag web are hereby formed.

In Fig. 4 appears a situation with foldings in the first film web 70', i.e. after the position of the folding blade 108. Each folding will have a width 122. This width depends on the desired size of the bag and may e.g. be between 25 and 75 mm, preferably between 45 and 55 mm. There is a spacing 124 between two succeeding foldings 46. This spacing may have a size between 25 and 75 mm, preferably between 45 and 55 mm.

The above dimensions will depend on the desired bag size. The two support plates 112 shown in Fig. 5 operate such that the support plate to the right will be a fixed support plate. The support 112 to the left may be movable. Alternatively, a vacuum brake 126 can be applied, holding the film web when the folding is to be formed. The support plate 112 to the left will also have an edge area that is used for the formation of a second folding line located between the folded part and the first film web 70'.

Figs. 6-8 show different steps by the formation and fixing of the folding.

Fig. 6 shows how the support plate 114 is provided with needles 128. The needles 128 can be moved through apertures in the support plate and engage the first film web 70'. There is hereby provided particular certainty of correct formation of a folding line as this is not only formed by squeezing between the folding blade 108 and the support plate 114.

The needles 128 can be extended and withdrawn from engagement with the film web 70'. After forming the folding by moving the support plate and the folding blade 108 to the lower position shown in Fig. 7, heating pins 130 are moved through apertures in the support plate and brought to engage the folded parts such that the foldings are fixed by spot weldings. When a heat fixing of the folding has been performed, the support plates 112 can be pivoted out of engagement or displaced out of contact with the fold by a translational movement in transverse direction of the film web.

The first film web 70' with the foldings fixed thereon is then ready for further conveying. By the further conveying there may be used a top belt 132 as indicated in Fig. 8. However, such a top belt can also be dispensed with. The top belt 132 can be a vacuum belt pulling the first film web 70' . Alternatively, the second film web 70 can be moved at the front side of the top belt 132 such that the two film webs are moved together along the bottom side of the top belt.

Before providing a more detailed description of the way in which the foldings for the formation of the folded side sections are formed, with reference to Figs. 9-16 there will be provided a more detailed explanation of the way in which the bag bottom is formed, in case of a standing bag. It is noted that Figs. 9-16 therefore describes a bag with standing bottom. Alternatively, instead of using a folded bottom section a longitudinal welding along the long side edge of the two film webs 70, 70' is applied, such that a bag only with the side edges folded will appear.

As it appears on Fig. 9, the first film web 70' has a greater width than the second film web 70. There is thus a peripheral area 76 of the film 70' that extends beyond the outer edge of the film web 70.

Fig. 9 illustrates a situation where the two film webs 70, 70' are brought together. The second film web 70 is therefore moved down towards the first film web 70' with the folded side edges spot welded at a position between the two film webs 70, 70' as a spot welding has been performed as mentioned in connection with Fig. 7. Furthermore, a transverse welding 66 has been performed as mentioned in connection with Fig. 5, such that the bag item along foldings appears with weldings that strengthen the bag. By this step, the folded side edges are therefore welded to the film webs 70, 70' at the parts constituting the corners of the bag between the flat sides and the folded bag sides. Fig. 9 shows that the weldings 66 extend across part of the length of the folded side sections 46.

The film webs 70, 70' will usually be made slightly wider than illustrated at the side where the bag bottom is to be formed. Such an extra width at the peripheral area of the film webs is important in practice in order to have a sufficient amount of film to grip at the folding of the film webs.

Fig. 10 shows a beginning folding for formation of a standing bottom. A peripheral area 78 of the first film web 70' is folded about a folding line 80 upwards according to arrow 82. As seen, the folded side sections 46 will be opened hereby.

Fig. 11 shows a subsequent step where the film web 70' is folded 180° back such that the peripheral area 78 is disposed upon the remaining part of the film web 70' . This means that the folded side section 46 is now completely open and appears flat.

In Fig. 12 is seen a following step where the peripheral area 76 of the film element 70 is folded about the folding line 84 by folding according to arrow 86. The folding line 84 is defined as the outermost point of the side sections 46. The edge area 76 is folded in over the side sections 46 and the first film web 70'.

Fig. 13 shows the fully folded position where the edge area 76 is folded 180° in over the other film elements. It appears that the edge area 76 covers the two unfolded and open side sections 46.

Fig. 14 illustrates a subsequent step where a transverse welding 88 is effected throughout the entire length of the side sections. The side sections 46 are located in the part 90 which subsequently will constitute part of the stand bottom in a bag.

Fig. 15 shows that the second film web 70 is now welded together with the side sections 46 and the first film web 70', and then folded 180° back over the line 80. Fig. 16 illustrates a final step where the film webs 70, 70' are provided with longitudinal weldings 92 that will form edges in the stand bottom of a finished bag.

After the step shown in Fig. 16 it is preferred that the bottom film is trimmed. Hereby the extra width of the film webs 70, 70' mentioned in connection with Fig. 9 is removed, and which has been used for gripping when folding the film webs.

By the above described steps, now there will be formed a bag web with contiguous bag items 12. The bag items 12 can be separated by slits along the line 94 such that they appear in a form corresponding to the one shown in Fig. 1 where the bag items 12 at their upper edge (not shown in Figs. 6-16) are connected with the peripheral strip areas 50.

The bag web can be stored on a roll or by zigzag folding in boxes. In Figs. 6-16 is not shown how a zipper is introduced in the process. However, a zipper 58 as illustrated in Fig. 2 will be inserted on the film webs immediately before the joining of the film webs illustrated in Figs. 4 and 5. A zipper 58' as illustrated in Fig. 3 will also be inserted in the film webs immediately before the joining of the film webs illustrated in Figs. 4 and 5. In connection with Figs. 6-16 is illustrated a specific embodiment of a method for forming the bag items. By this embodiment, the edge area 76 of the film web 70 will be used for formation of the bottom of the bag item. The bottom may alternatively be formed of film sections that are inserted separately.

By the making of the film web it is thus possible to use the production methods explained in EP 1 250 999. However, it is to be noted that by the technique disclosed in EP 1 250 999 there may optionally be used film webs which at their upper side have a peripheral area which can be used for forming the peripheral strip areas with the star- shaped perforations.

Fig. 17 shows in detail foldings with folded side sections as a folding blade 108 is used which interacts with a support plate 114.

In step A, no advancing occurs by the two roller pairs 106 and 110 (see Fig. 18). The first film web 70' is located at a position below the support plates 112 and with the folding blade 108 disposed below the film web. Step B shows a commencing folding as the folding blade 108 and the support blade 114 are moved upwards while at the same time the needle 128 is maintained at a positon above the support plate 114. The roller pair 110 is retained in this situation, while the roller pair 106 provides advancing 153 of the film web. In step C, the folding blade 108 is in its fully extended position, and the needle 128 is moved down to engage the film web 70' . Here there will be formed a first folding 134 along a first folding line 136 at the edge 138 of the folding blade 108. No movement of the film web occurs at this position as both pairs of rollers stand still. In step D, the folding blade 108 and the support plate 112 are displaced downwards as the needle 128 maintains its engagement, ensuring that the film web does not slide. As seen, a beginning outward bending of the folded part of the film web is established. In this position, the folded part will be folded down against the first film web 70' about a second folding line 140. The second folding line 140 will be formed at the edges of the two support plates 112. At the same time, a folding about third folding lines 142 of the parts located at either side of the folding blade 108 will occur.

In step E, the folding blade 108 and the support plate 114 are moved to the lower position where foldings are now formed by folding around the two support plates 112. The film web is still held without movement. The needle 128 is withdrawn when in this position.

Folding blade and holding plate are omitted in step F. In step F, a spot welding is performed by means of the heating pins shown in Fig. 7. The spot weldings are indicated by 144. The spot weldings will be performed through the folded parts in immediate vicinity of the other folding lines 140. By fixing the foldings, the film may withstand the tension established in the film 1 when it is conveyed by the roller pair 110 for subsequently being superposed by the second film web 70, as illustrated in Fig. 5.

Step G shows the first film web when a full welding 146 has been performed along the other folding lines 140. Step G may optionally be performed before or after bringing the two film webs together.

Fig. 18 shows a partial view of a further embodiment of the invention. In Fig. 18 is seen that a single folding blade 108 is also used for forming a fold. The folding blade interacts with a top belt 132 formed of a number of juxtaposed belts 148. In the shown embodiment, the second film web is moved down under the top belt such that it is brought into contact with the first film web even when the latter is displaced upwards in contact with the top belt 132.

The top belt 132 therefore operates in the same way as the support plate 114 when it pivots up and down about a pivot axis 152, ensuring clamping of the first film web 70 between the folding blade 108 and the belts 148 of the top belt 132.

Spot welding along the folding lines is provided by the heating pins 130 in the same way as described in connection with Fig. 17. In this embodiment, vacuum boxes 126 are used interacting with support plates 112 (not shown in Fig. 18). By this embodiment a higher speed can be attained as establishing folding is effected simultaneously with superposition of the two film webs.

After superposing the two film webs and welding, the two superposed film webs with the folding provided there between through the welding station 120. In the welding station 120 is established a welding along the other bending lines, as explained in connection with Fig. 17. At the same time is established a welding between the second film and the edge are of the folded parts adjoining the first folding line.

A welding will hereby be formed along the folding lines that subsequently form corners in the bag. This imparts strength to the bag. Fig. 19 shows schematic drawings of steps by the method shown in Fig. 18, illustrating how the top belt 132 interacts with the folding blade 108.

In step A, the starting position appears where the folding blade 108 is in its lower position under the first film web 70' . The top belt 132 is pivoted to a position in parallel with the film web 70' and the underlying part of the film web 70 that is passed around the top belt 132.

Step B shows a commencing folding as the folding blade 108 and the top belt 132 perform an upward pivoting 115. The roller pair 110 is retained in this situation, while the roller pair 106 provides advancing 153 of the film web. This corresponds to step B in Fig. 17.

In step C, the fully extended position of the folding blade 108 is seen at the same time as the top belt is in its fully pivoted position. In this situation there are no movements or advancing of any of the roller pairs and no conveying of the second film web 70 occurs as well.

In this position, the first film web 70' is retained along the edge area 134 of the folding blade. Hereby a folding line 136 is formed. As seen in step D, there is now a commencing folding at the downward pivoting 150 of the top belt 132. In this position, a certain tension occurs in the second film web while the first film web 70' is retained. In step E, the downward pivoting of the top belt is completed, and in this position the heating pins are activated such that a spot welding is provided along the other folding lines, as explained in connection with Fig. 17.

Step F shows a completed folding after leaving the position under the top belt. At this position transverse weldings 16 are formed in the welding station 120 shown in Fig. 18. Transverse weldings are thus established at the edge areas that subsequently form corners in the bag. A bag with strong corners is thus provided in a way corresponding to that described in connection with Fig. 17. Fig. 20 shows a schematic drawing corresponding to Fig. 19. However, in this embodiment are used two folding blades 108 that are displaced up in gaps between three support plates 112. In this embodiment, the folding blades also interact with the top belt 132. In step A, the starting position appears with the folding blades retracted.

In step B appears how the folding blades 108 are extended such that folding is formed corresponding to the third foldings 142 at the edge areas 138 of the folding blades. At the same time, other foldings at the folding lines 140 are formed at the edges of the support plates 112.

In step C appears how the folded parts are pivoted downwards against the first film web 70' as indicated by arrows 154. By the pivoting the folding blades are retracted from their position within the folded parts.

In step D, the folding will thus have a form corresponding to the one illustrated in step F in Fig. 17. The folding is then brought into engagement with the second film web 70 as the top belt 132 performs a downward pivoting 50 such that the folding is squeezed between the first film web 70' and the second film web 70. Heating pins 130 are then activated. Thereby spot welding are established, as illustrated in step F where the heating pins 130 are moved into contact with the film webs in gaps between the belts of the top belt. Similar to the above description there is hereby established spot welding at position at the other folding lines between the folded parts and the first film web 70' and in the area between a position for a first folding line and the second folding line 70.

It appears in step G how the top belt 132 is pivoted to its upper position, and the folded parts are moved outside the first roller pair where the welding station 120 is provided. The welding station 120 forms longitudinal weldings as explained previously in connection with Fig. 17.

Fig. 21 shows a first film web 70' of the type provided with a peripheral area perforated by a series of perforation holes 18. This is seen in the lower Figure where the film web 70' is formed with a folding for formation of the folded side sections, as already explained above. The lower part of Fig. 21 illustrates a broken line 155, a line of symmetry through the fold. A film sheet appears in the upper part before perforation and folding have been performed. Here it is seen that along one edge area, which subsequently constitutes the peripheral area of the bag web, is formed a cutout 156. The cutout is has a length that is equally long at either side of the line of symmetry 154. By the formation of the folding, the side edges 158 of the cutout will thus be provided in immediate continuation of each other.

By such a design it is possible to use the method according to the invention for forming bag items that can be used in a conveying system and in a filling apparatus as explained in connection with Figs. 1-3. No excess material will therefore appear in the peripheral areas 40 which will prevent correct engagement between the perforation holes 18 and holding pins 28 in the apparatus. Fig. 22 shows an enlarged view of the area at the foldings. Furthermore, it is seen how the foldings are formed in the first film web 70' and then joined with the second film web 70. The foldings forming the folded side sections 46 are shown in enlarged form. It is seen that spot weldings 160 are provided at the folding lines 140. Moreover, it appears that also at these other folding lines 140 a welding 146 is formed at a position between the first film web 70' itself and the adjoining folded part, which is situated at the other side of the folding lines 140. Correspondingly, weldings 146 are formed between the second film web 70 and edge areas at either side of what would have constituted a first folding line 136. The weldings are provided by welding through all film layers in heating zones as indicated by 162. The two film webs are formed of multi-layered polymer films of which a first layer 162 is weldable and of which a second layer 164 is not weldable. Weldings therefore only appear between the weldable parts/surfaces.

After welding the two film webs together, a cutting is performed for forming the slits 10 shown on Fig. 1. A cutting is thus provided along a cutting line 166. A bag web 4 will hereby be formed of the continuous film webs 70, 70'.

Claims

1. A bag web with a continuous web of laterally folded bag items, which are formed of a first and a second superposed film web forming opposing front and back sides of a bag item, characterised in that the folded parts of the first film web are disposed between the front and back sides of the bag item for forming at least one first folded side in the bag item, the first folded side formed of material from the first film web.

2. Bag web according to claim 1, characterised in that the folded parts of the first film web also form a second folded side in the bag item.

3. Bag web according to claim 1, characterised in that the two superposed film webs have the same width, and that the folded parts extend across the entire width of the film webs or of a part thereof.

4. Bag web according to claim 1 or 2, characterised in that the folded parts are attached to the first film web from where the folded parts are unfolded by spot welds along folding lines between the folded part and the associated film web.

5. Bag web according to any preceding claim, characterised in that the superposed film webs are made of multi-layered films, where at least one outermost layer of the first and second film webs facing the other film web is made of a weldable plastic material, preferably PE or PP, and where at least one outermost layer of the first and second film webs facing away from the other film web is made of a non-weldable plastic material, preferably PET, OPA or OPP.

6. Bag web according to any preceding claim, characterised in a zipper is provided on the first or on the second film web, the zipper including interacting zipper parts, and that in connection with the zipper and in parallel therewith a weakening line or perforation is provided which is easily torn up for establishing an access opening to the interior of a finished bag, the access opening capable of being opened and closed by means of the zipper.

7. Bag web according to any preceding claim, characterised in that the bag web along its opening edges includes peripheral strip areas prepared with a series of holes or corresponding star perforations intended for guide connection with guide means, which are arranged for retaining and guiding peripheral areas at the opposing bag opening edges along a conveyor path through a filling station, the bag web being of the type consisting of a contiguous series of bag items separated by a number of slits that extend from a bottom edge of the web up to a point below an upper edge of the web.

8. Bag web according to claim 7, characterised in that the folded parts extend across part of the width of the film webs, and that material located in the edge area of the bag webs opposite the folded parts and at bag opening edges is removed over a distance in the length of the film webs corresponding to the length of the film web used for forming the folded parts, such that the edge area appears largely unbroken and without folding.

9. A method for producing a bag web with a continuous web of laterally folded bag items, which are formed of a first and a second superposed film web forming opposing front and back sides of a bag item, and wherein the folded parts of the first film web are disposed between the front and back sides of the bag item for forming folded sides in the bag item, characterised in that the method includes steps, wherein: A - a first and a second superposed film web is conveyed from a film web storage; B - a part of the first film web is folded as at least one folding blade is displaced in a direction transversely to the conveying direction of the first film web in direction towards the second film web, hereby establishing a first folding along a first folding line at the edge of the folding blade;

D - fixing the folded part in its position in contact with the first film web;

E - placing the second film web in a superposed position over the first film web;

F - welding the two superposed film webs together with transverse weldings at the folded parts such that the folded parts are disposed in the bag items between front and back sides of the latter; G - welding the two superposed film webs together at least along a longitudinal side edge at a bottom of the bag items.

10. Method according to claim 9, characterised in that

11. Method according to claim 9, characterised in that

12. Method according to any of claims 9-11, characterised in that the method includes choosing film webs made of multi-layered films, where at least one outermost layer of the first and second film webs facing the other film web is made of a weldable plastic material, preferably PE or PP, and where at least one outermost layer of the first and second film webs facing away from the other film web is made of a non- weldable plastic material, preferably PET, OPA or OPP.

13. Method according to any of claims 9-12, characterised in that- step B includes retaining the first folding along the first folding line at the edge of the folding blade by squeezing the film web between the edge of the folding blade and a support.

14. Method according to any of claims 9-13, characterised in that

15. Method according to claim 13 or 14, characterised in that - step D includes fixing of the folded part being performed by means of welding means provided in the support.

16. Method according to any of claims 9-15, characterised in that

- step A includes conveying the first and possibly also a second superposed film web from a film web storage by using a first set of rollers before the folding step and a second set of rollers after the folding step, wherein the rollers are squeezing the associated film web and are applied for the conveying of the film web, in that the first and second pair of rollers have differentiated rotation during the folding step.

17. Method according to claim 16, characterised in that

- step F is performed at a position after the second set of rollers.

18. Method according to any of claims 9-17, characterised in that

the method includes an additional step H where between the succeeding bag items a transverse cutting is performed that extends from a bottom edge of the film webs up to a point below a top edge of the web for the formation of a contiguous series of bag items divided by a number of slits.

19. Method according to any of claims 9-18, characterised in that

along its opening edges, the bag web includes peripheral strip areas prepared with a series of holes or corresponding star perforations that are intended for guide connection with guide means, which are arranged for retaining and guiding peripheral areas at the opposing bag opening edges along a conveyor path through a filling station.