EP0993933B1 - Method of manufacturing multiple walled, preferably double walled, plastic bags - Google Patents

Description

The invention relates to a method for producing multi-walled, preferably double-walled plastic bags, in particular drawstring bags at least one film web fed continuously from an unwinding station thermoplastic plastic.

From DE 44 33 582 it has become known to have plastic bags with a double layer Front and rear wall made of two flat film webs pulled from unwinding rolls in that the two film webs are initially brought together in opaque fashion and then folded over like a U. Then in one Open head area punched holes and each between the outer and inner web layer a drawstring is inserted, whereupon the web layers in the head area welded in pairs. Finally, side welds and if necessary, a perforation is introduced to form the individual plastic bags.

With such a production method, the width of each film web corresponds to the output side twice the height or length of a finished plastic bag.

From practice it is also known to use one instead of two wide flat webs to use a correspondingly wide, flat-laid hose track, like the flat tracks is folded around a substantially central longitudinal axis in a U-shape. The others Operations such as inserting the grip holes, inserting the drawstring, Perform the welding operations and so on as when using U-shaped flat webs made.

Regardless of whether you have two parallel flat tracks or a closed one Tubular web runs out, the comparatively large web width of the film web is both with regard to their manufacture as well as their processing with considerable disadvantages connected. So z. B. a 2000 mm wide film tube for producing a 1000 mm long double-layer plastic bag not without difficulties extrude. In addition, the investment for such a large extrusion plant quite high. After all, comparatively wide film webs are extremely because of their thin thickness in the range of, for example, 6 µm to 8 µm is difficult to handle. In any case, such a procedure can only be carried out at low production speeds be worked.

US 4,481,669 describes a process for the production of multi-walled bags Made of flexible plastic, with the layers one above the other in the longitudinal direction folded, flat web of a first flexible film on one edge opposite the Fold line to be opened at least partially and into the second flexible plastic film a deflection guide into the space between the two at least partially open Layers of the first plastic film is inserted around the fold line of the second Plastic film at least essentially in alignment with the fold line of the first Bring plastic wrap. The two tracks move synchronously into one Direction to at a sealing station transverse to the direction of movement of the two webs to be sealed. A number of open bags are formed, the bottom of which each through the aligned fold lines of the two panels and their opening area is formed by the edge of the web over the fold line.

The invention has for its object a method for producing multi-walled, preferably double-walled plastic bags, especially drawstring bags, to propose by processing foil webs in the form of tubular webs and / or flat films is significantly simplified and thus with the best possible quality comparatively high production speeds are possible.

This object is achieved in that several, for example two Foil sheets each double-layered compared to a single-layer sheet width, in. substantially half the web width unwound from an unwinding roll of the unwinding station and then be folded up to the full web width in one layer. The advantages of such Procedures are obvious. For the extrusion a smaller plant and thus also requires a lower investment. A film tube of, for example, 1000 mm width is easier to extrude than, for example, a film tube from 2000 mm width. When using a double-layer film web in the form of a tubular web is this according to an expedient embodiment of the invention by an im cut open essentially central longitudinal section on one wall side, whereupon the path areas lying on both sides of the cutting line together with the other Folded up the wall side of the tubular web into a full-width flat foil web become. The center cut reduces the opening width by half. Moreover the middle cut gives a straight edge on both sides, which is congruent Overlapping the film webs and welding together is essential simplify.

In an expedient embodiment, the tubular webs are in the running direction unfolded flat film webs fed, the film webs by appropriate Deflection devices are performed.

The hose tracks can also be essentially transverse to the direction of the fed flat, unfolded film webs and guided over turning bars.

In principle, it is also possible for several, for example two, half-tube webs are folded into flat sheets, which are folded up and covered folding together like a U in a bag making machine into plastic bags are processed. In this case, the semi-tubular webs are from Distance between unwinding rolls to higher, the half-tube webs to the full width of a flat sheet folding triangles of Folding facilities led.

Figur 1

eine perspektivische Darstellung einer ersten Herstellweise von doppellagigen Kunststoffbeuteln,

Figur 2

einen als Zugbandbeutel ausgebildeten doppellagigen Kunststoffbeutel,

Figur 3

einen Schnitt nach der Linie III-III der Figur 1,

Figur 4

eine Schnittdarstellung nach der Linie IV-IV der Figur 1,

Figur 5

eine abgewandelte Verfahrensweise mit quer zugeführten Schlauchbahnen und

Figur 6

eine weiter abgewandelte Verfahrensweise zum Herstellen von Kunststoffbeuteln aus quer zugeführten Halbschlauchbahnen.

Preferred embodiments of the invention are shown in the drawing and are explained in more detail below. Show it:

Figure 1

1 shows a perspective illustration of a first production method for double-layer plastic bags,

Figure 2

a double-layer plastic bag designed as a drawstring bag,

Figure 3

2 shows a section along the line III-III of FIG. 1,

Figure 4

2 shows a sectional illustration along the line IV-IV in FIG. 1,

Figure 5

a modified procedure with transversely fed tube sheets and

Figure 6

a further modified procedure for the production of plastic bags from cross-fed half-tube webs.

An unwinding station 1 shown in FIG. 1, one not shown in detail Device for producing plastic bags 2, in particular drawstring bags, see above as shown in Figure 2, has a first unwinding roll 3 for feeding a first film web 4 and an unwinding roll 5 for feeding a second film web 6 on. The film webs 4, 6 are each designed as a tubular web, for example has a width of 1000 mm. The tubular web 4 can be cut through a cutting knife 7 a middle cut should be cut open so that there is a cut line on both sides lying edge areas of the film web 4 via a corresponding guide device 8 Unfold to the full width, i.e. 2000 mm. The flat web unfolded in this way becomes via a deflecting rod 9 in a manner described in more detail below to a led individual bag making machines, not shown. The unwind roll 5 is with Distance behind the unwinding roller 3 and the unwinding roller 5 is the likewise designed as a tubular web of film 6 also by a cutting knife 10 separated in the middle and led up and there also by one Deflection rod 11 folded so that this film web covers the first film web 4 to a folding device 12 upstream of the bag making machine with a Folding triangle 13 is supplied. In this folding device, the two become opaque lying tube sheets folded in a U-shape to half the width, so that finally A double-layer film arrangement is formed on both sides, as is designated by 14 and finally, in a manner not of interest here, as known per se, the Plastic bag 2 or drawstring bag can be produced. As can be seen from Figure 1, the respective tubular web 4 to 6 in Direction of the fed unfolded flat webs fed.

In the procedure shown in FIG. 5, first of all, a half-width having tube sheets 4 and 6 after cutting them open in the middle via the cutting blades 7, 10 and the guide device 8 double-wide flat webs generated, due to the transverse feed of the tube sheets 4, 6 via turning bars 15 are guided to the folding device 12.

FIG. 6 shows a further modification of the procedure. There are on the Winding rolls 3, 5 semi-tubular webs 16, 17 wound, each with its own Folding triangle 18, 19 are unfolded into a flat sheet of film, which is then opaque are guided to another folding device 21. The latter corresponds to about the folding device 13 in the embodiment variants of FIGS. 1 and 5.

As a rule, the unwinding rolls are located. H. the unwind station 1, lower than that higher located turning and deflecting rods or folding triangles, so that the supplied half-wide film webs are led from bottom to top and then in substantially horizontally when the width is fully unfolded.

It is understood that within the scope of the claims on the individual unwinding rolls different foils, d. H. in terms of both thickness and material, can be wound up.

Claims (10)

1. Method of manufacturing multiple walled, preferably double walled, plastic bags (2), in particular strips of tear-off bags, from at least one film web (4, 6) fed continuously from an unwinding station (1) in the form of flat films and/or tube webs of thermoplastic, for example two film webs (4, 6) first being fed so as to cover each other and then being folded over in the manner of a U, the layers of the webs being welded shut in pairs, at least in the top area, characterized in that a plurality of film webs (4, 6) are in each case unwound in double layers, with a web width substantially half that of a single layer web width, from an unwinding reel (3) in the unwinding station (1) and are then folded out to full web width in a single layer, the film webs (4, 6) laid flat then being led together in a known way so as to cover each other and then folded over in the manner of a U, and the plastic bags (2) finally being produced in an automatic bag making machine from the folded film webs (4, 6).
2. Method according to Claim 1, characterized in that the double layer film webs (4, 6) wound up on the unwinding reels (3) of the unwinding station (1) are formed as tube webs, which are each cut open by a substantially central longitudinal cut on their one wall side, the web regions lying on both sides of the cut line, together with the other wall side of the tube web, being folded open to form a full-width flat film web (4, 6).
3. Method according to Claim 2, characterized in that the longitudinal cut in the tube web is carried out as the tube web runs up substantially in the vertical direction from the unwinding station (1) placed at the bottom to a deflection arrangement (9, 11) placed higher up.
4. Method according to one or more of Claims 1 to 3, characterized in that the tube webs are fed in in the running direction of the film webs (4, 6) folded out flat.
5. Method according to one or more of Claims 1 to 3, characterized in that the tube webs are fed in substantially transversely with respect to the running direction of the film webs (4, 6) folded out flat.
6. Method according to Claim 5, characterized in that the film webs (4, 6) are guided over turner bars (9, 10).
7. Method according to Claim 1, characterized in that a plurality of half tube webs (16, 17), for example two, are folded out to form single layer flat webs, which are laid together so as to cover each other and, after being folded over together in the manner of a U, are processed to form plastic bags (2) in a bag making machine.
8. Method according to Claim 7, characterized in that the half tube webs (16, 17) are guided from unwinding reels (3, 5) located at a distance beside each other to folding triangles (18, 19) of folding devices which are placed higher up and widen the half tube webs (16, 17) out to the full width of a flat web.
9. Method according to Claim 8, characterized in that the flat webs are in each case guided substantially in a horizontal guide plane downstream of a deflection bar of the associated folding device (21).
10. Method according to Claim 9, characterized in that the flat webs at the end of the guide plane are guided substantially vertically downwards over a common deflection bar of a further folding device (21) and, by a common folding triangle belonging to the further folding device (20), are brought into the U shape necessary for the purpose of manufacturing the plastic bags (2).

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