GB2121721A

GB2121721A - A process for the manufacture of plastics carrier bags

Info

Publication number: GB2121721A
Application number: GB08315901A
Authority: GB
Inventors: Hans Lehmacher
Original assignee: Lemo M Lehmacher and Sohn GmbH Maschinenfabrik; M Lehmacher and Sohn GmbH Maschinenfabrik
Current assignee: Lemo M Lehmacher and Sohn GmbH Maschinenfabrik; M Lehmacher and Sohn GmbH Maschinenfabrik
Priority date: 1982-06-15
Filing date: 1983-06-09
Publication date: 1984-01-04
Also published as: GB2121721B; DE3222376C2; GB8315901D0; DE3222376A1

Abstract

A process for the manufacture of plastics carrier bags from a flattened plastics tube 1 in which the plastics tube is divided in its longitudinal central area into two half-tube widths with wave crests and wave troughs along the severed edges and a fold along the outermost edges, the wave crests of the half-tube widths are provided with reinforcement units, blanked-out handles are formed in the areas of the reinforcement units, and individual carrier bags are subsequently separated from the half-tube widths, e.g., by separating welds, is characterised in that the two half-tube widths are transversely separated and longitudinally displaced such that the wave crests are transversely aligned, the edges of the upper layers folded back Figure 6 and the reinforcing units 7 applied to the exposed inner faces of the upper and lower layers, following which the folded edges are unfolded and the blanked-out handles 8 formed. <IMAGE>

Description

SPECIFICATION A process for the manufacture of plastics carrier bags This invention relates to a process for the manufacture of plastics carrier bags from a flattened plastics tube and to a plastics bag so produced, in which the plastics tube is divided in its longitudinal central area into two wave-shaped half-tube widths with wave crests and wave troughs along the severed edges and a fold along the outermost edges, the wave crests of the half-tube widths are provided with reinforcement units and blanked-out handles are formed in the areas of the reinforcement units, and in which moreover the individual carrier bags are subsequently separated from the half-tube widths, e.g., by separating welds. The wave crests and the location of the blanked-out handles cause as it were carrying loops to be formed.Processes of this kind are known to operate continuously or with a continuous fixed cycle.

In one known process of this type, the reinforcement units, which are cut off from strip-form material that is fed in, are applied externally to the wave crests on the underside and on the upper side, which is expensive. Also, the half-tube widths are longitudinally displaced relative to one another such that one wave crest of one half tube lies on top of a wave crest on the other half-tube so that the blanked-out handles of two plastics carrier bags can be formed by one stroke of the press.

It is also known to locate reinforcement units on the internal surfaces of plastics carrier bags that are manufactured from a flattened plastics tube. However in this case the plastics tube is initially cut apart in its upper layer only, this being with a straight-line dividing cut. The edges so exposed are folded back and the reinforcement units are applied both to the folded-back edge strips and to the exposed area lying between them. Unfolding, punching and separating take place subsequently. This method of working however cannot be carried out if dealing with the manufacture of plastics carrier bags that are to feature blanked-out handles in the area of the wave crests in the manner described, so that in the finished condition as it were carrier loops are formed.

It is the basic problem of the invention to conduct the generic process in such a way that the reinforcement units are located internally in the completed carrier bags and can be applied from above.

According to the present invention, a process for the manufacture of plastics carrier bags from a flattened tube of plastics material, comprises dividing the plastics tube in its longitudinal central area into two wave-shaped half-tube widths with wave crests and wave troughs along the severed edges, and a fold along the outermost edges, the wave crests of the half-tube widths being provided with reinforcement units and blanked-out handles formed in the areas of the reinforcement units, and in which the individual carrier bags are subsequently separated from the half-tube widths, the two half-tube widths being separated transversely and longitudinally displaced relative to one another such that the wave crests on each half-tube are transversely aligned, and at the same time or subsequently an edge strip of each of the upper layers of the half-tube widths with wave crests and wave troughs folded back towards the base fold, the reinforcement unit being applied to the exposed inner surface of the wave crests and subsequently the edge strips unfolded, after which the blanked-out handles are formed. There are several possibilities of further detailed improvement and design within the scope of the invention.In order to hold the edge strips of the half-tube widths firmly and securely for further operations, a preferred method of performance of the invention is characterised in that the edge strips of the half-tube widths are folded back with the wave crests and wave troughs as well as with an additional proportion of the upper layers to form a stabilization strip, so that by the tensional force acting on the stabilization strips, the edge strips are adequately firmly held both when applying the reinforcement units and when forming the blanked-out handles. In this connection it is also desirable to fix the edge strips in their folded-back state electrostatically in the region of the wave crests and to apply the' reinforcement units subsequently. Within the scope of the invention the plastics tube can be separated into two half-tube widths by a longitudinal cut of sinusoidal shape.A wave-shaped longitudinal cut, the waves of which are of trapezoidal shape, can however also be used.

The advantages achieved are to be seen in that in carrying out the process according to the invention the reinforcement units are located in the interior of the completed plastics carrier bags, which posses as it were loop-shaped handles. Of particular advantage is the fact that the reinforcement units themselves no longer have to be applied from above and below but can be put on from above. This allows great production speed in the manufacture of plastics carrier bags by the process of the invention, equally so whether the operation is continuous or has a fixed cycle. Of particular advantage is the fact that the process according to the invention can be carried out comparatively simply in respect of the machine used.In its basic construction a machine to carry out the process according to the invention is not designed very differently from known machines but does need an additional separating unit and a rearrangement of the station that displaces the half-tube widths relatively to one another with wave crest against wave crest. There could on the other hand even be certain simplifications brought about in the feeding-in of the reinforcement units beause they now only have to be applied from above.

One example of the invention will now be described with reference to the accompanying drawings, in which Figures 'to 9 show perspective views of the individual steps of the process according to the invention.

The process according to the invention starts with a flattened tube S of plastics material as can be seen in Figure 1. The succession of Figures 1 and 2 shows in the first place the division of the plastics tube into two half-tube widths 1 by a longitudinal dividing cut 2, which in the example is of sinusoidal shape and forms wave crests 3 and wave troughs 4. When Figure 3 is added it can be seen that the two half-tube widths 1 are separated transversely and longitudinally displaced relative to one another, with wave crest 3 against wave crest 3. What takes place, referring to the sinuosidally-shaped dividing cut 2, is the equivalent of a phase displacement of half a wavelength.At the same time or subsequently, an edge strip 5 of each of the upper layers of the half-tube widths with wave crests 3 and wave troughs 4 folded back towards the fold at the outer edges of the half-tube widths as has been indicated in Figure 4. Here Figure 4 also shows a preferred form of the invention, in which the edge strips 5 of the half-tube widths 1 are folded back with the wave crests 3 and wave troughs 4 along with an additional proportion of the upper layer forming a stabilization strip 6. The edge strip 5 as a whole is tightly held in the folded condition by tensional force acting an the stabilization strip 6. It is also electrostatically fixed in the folded state in the area of the wave crests 3, as has been represented in Figure 5.

Figure 6 makes it clear that in addition to this, reinforcement units 7 are applied to the exposed inner surfaces of wave crests 3. Subsequently the edge strips 5 are unfolded, for which reference is made to Figure 7. In Figure 8 are seen the blankedout handles that are in the meantime formed and Figure 9 shows the individual carrier bags 10 which have been separted from the half-tube widths 1 by separating welds.

Claims

1. A process for the manufacture of plastics carrier bags from a flattened tube of plastics material, comprising dividing the plastics tube in its longitudinal central area into two wave-shaped half-tube widths with wave crests and wave troughs along the severed edges, and a fold along the outermost edges, the wave crests of the half-tube widths being provided with reinforcement units and blanked-out handles formed in the areas of the reinforcement units, and in which the individual carrier bags are subsequently separated from the half-tube widths, the two half-tube widths being separated transversely and longitudinally displaced relative to one another such that the wave crests on each half-tube are transversely aligned, and at the same time or subsequently an edge strip of each of the upper layers of the half-tube widths with wave crests and wave troughs folded back towards the base fold, the reinforcement units being applied to the exposed inner surface of the wave crests and subsequently the edge strips unfolded, after which the blanked-out handles are formed.

2. A process according to Claim 1, wherein the edge strips of the half-tube widths having the wave crests and wave troughs are folded back along with an additional proportion of the upper layers to form a stabilization strip, and are firmly held in the folded-back state by the tensional force acting on the stabilization strip.

3. A process according to Claim 1 or Claim 2, wherein the edge strips in their folded-back state are electrostatically fixed in the region of the wave crests and the reinforcement units are applied subsequently.

4. A process according to any of Claims 1 to 3, wherein the plastics sheeting tube is separated into two-half widths by a longitudinal cut of sinusoidal shape.

5. A process according to any of Claims 1 to 3, wherein the plastics sheeting tube is separated into two half-tube widths by a longitudinal cut of trapezoidal wave shape.

6. A process for the manufacture of plastics carrier bags subsantially as hereinbefore described with reference to the accompanying drawings.

7. A plastics bag when produced by the process of Claim 1.

8. A plastics bag when produced by the process of Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.