Gas-filled body

Abstract

The invention concerns a plastic tube (1) which is prefabricated for the production of gas-filled filling bodies. The plastic tube (1) comprises an upper film and a lower film which are in mutually superposed relationship and which are connected together along their two longitudinal edges (4, 6). In that case provided in the upper film is a transverse cut (12) which is preferably cut in at its ends by stampings (10). In addition the upper film and the lower film are subdivided into individual pockets (7) by weld seams extending in the transverse direction and spaced from each other. The plastic tube can be easily filled by injecting a filling gas, wherein after inflation of the pockets (7) the open ends thereof are welded.

Description

The invention concerns a prefabricated plastic tube for the production of gas-filled filling bodies, comprising an upper film and a lower film which are gas-tightly connected together in mutually superposed relationship at a first of their longitudinal edges and which are welded together to form inflatable pockets in a transverse direction by gas-tight weld seams arranged at a spacing relative to each other. The invention further concerns a gas-filled filling body for the packaging of articles, a process for the production of said plastic tube and of a gas-filled filling body, and an apparatus for carrying out the last-mentioned process.

Gas-filled filling bodies are used for example for cushioning articles in transportation cases in order thereby to prevent the articles being transported from being subjected to vibration or suffering damage. The filling bodies are first filled with gas immediately prior to use thereof and therefore can be delivered to and stored at the packager or consumer in a configuration such as to save on a great deal of space. A further advantage of the filling bodies is that, by virtue of their low weight, they scarcely increase the packaging weight and after use thereof they can be recycled without being separated into their respective constituents as they are usually made from a single plastic material.

In this respect, DE 199 13 408 A1 discloses a prefabricated plastic tube of the kind indicated in the opening part of this specification, in which the upper film and the lower film are welded together to form inflatable pockets in the transverse direction by mutually spaced pairs of gas-tight weld seams, wherein the weld seams extend from the first longitudinal edge to a predetermined distance from the oppositely disposed second longitudinal edge. The pockets each have a gas filling opening between the upper and lower films, which is accessible from the second longitudinal edge. As a full plastic tube is generally the initial starting point for the production of such a plastic tube, it firstly has to be divided in the longitudinal direction into two half-tube portions which are open at one side. That requires an additional working step before the actual operation for prefabrication of the plastic tube can be effected. A further problem with the known plastic tube is that the shrinkage which inevitably occurs with the welding of plastic films has the result that the film runs out of its original direction of transportation movement.

With that background in mind, the object of the present invention was to provide a prefabricated plastic tube and a process and an apparatus for the simpler production of filling bodies.

That object is attained by a plastic tube having the features of claim 1; by a gas-filled filling body having the features of claim 7, by a production process having the features of claim 8, by a process having the features of claim 11 and by an apparatus having the features of claim 14.

Advantageous configurations are set forth in the appendant claims.

The plastic tube which is prefabricated for the production of gas-filled filling bodies has two films which are referred to as the upper film and the lower film and which are arranged in mutually superposed relationship and which are gas-tightly connected together at a first one of their longitudinal edges. The upper film and the lower film are also welded together to form inflatable pockets in the transverse direction by mutually spaced gas-tight weld seams. The plastic tube is characterised in that the films are also connected together continuously at their second longitudinal edge and that one of the films which is defined hereinafter by definition as the upper film has a transverse cut in the transverse direction.

Unlike the known prefabricated plastic tubes the described plastic tube is closed at both longitudinal edges and has a transverse cut. That difference has on the one hand advantages in regard to manufacturing procedure as the initial starting point adopted is not a half-tube portion which firstly has to be cut out of a full tube in a separate working operation. Rather, it is possible directly to use a full tube (in a condition of being laid flat) so that an entire film tube can be filled in one working operation. The output of a corresponding manufacturing installation can thus be virtually doubled as there is no need for two half-tube portions to be filled in succession. In addition the transverse cut which is disposed in the transverse direction means that the weld seams to be applied for closing the pockets after inflation thereof also extend in the transverse direction. That is advantageous over a welding operation at a longitudinal edge as in the case of the known film as such welding and introduction of the air at a longitudinal edge of the film necessarily results in an asymmetry, by virtue of which the film can at one side run out of its previous direction of movement. In contrast such an asymmetry is avoided when a transverse cut is involved. The transverse cuts are preferably arranged symmetrically with respect to the center line of the plastic tube in order to exclude any ‘preferment’ of one side of the plastic tube, which could result in asymmetry.

In accordance with a preferred configuration of the plastic tube the weld seams which extend in the transverse direction are provided in pairs, wherein an intermediate space is provided between the two weld seams of each pair thereof, a perforation through the two films extending in the intermediate space in the transverse direction. Preferably the perforation extends continuously from one longitudinal edge of the plastic tube to the other. After the inflatable pockets have been filled and after they have been gas-tightly welded, the perforation permits the filling bodies produced in that way to be separated from each other by being torn away.

In accordance with another possible configuration of the plastic tube the transverse cut ends at at least one side but preferably at both at a certain spacing relative to the longitudinal edge of the plastic tube, wherein moreover a (short) incision in the longitudinal direction is disposed at said end. Such an incision which is perpendicular to the transverse cut interrupts the direction of run of the transverse cut and thereby prevents the upper film from being further unintentionally torn in the transverse direction. In addition the incisions have the advantage that the edge of the upper film, which is delimited by the transverse cut, thereby forms a freely movable flap which can be pivoted open or up when introducing the gas.

In accordance with another development of the plastic tube it has weld seams which are arranged in pairs and which extend in the longitudinal direction and between which is arranged a perforation also extending in the longitudinal direction. Pairs of weld seams of that kind with an interposed perforation also subdivide the plastic tube in the longitudinal direction into (at least) two portions so that correspondingly narrower inflatable pockets are formed. The narrower filling bodies formed therefrom permit a greater degree of flexibility in regard to their use as packaging material, wherein heightwise distribution of the filling bodies is overall more uniform than in the case of wider filling bodies.

As has already been explained hereinbefore the double-sided connection of the longitudinal edges of the plastic tube can be achieved by using a full tube in a laid-flat condition as the starting material. In order to increase the stability, which is reduced by the transverse cut, of the plastic tube for transport purposes or in order to allow smaller thicknesses for the plastic films with the same level of stability, a preferred embodiment of the invention provides that the longitudinal edges of the plastic tube are connected together by weld seams in the longitudinal direction.

The weld seams extending in the longitudinal direction (at the longitudinal edges or centrally in pairs) can be of a continuous configuration. Preferably however they are interrupted at the rhythm of the transversely extending weld seams, wherein their portions are respectively disposed with their first end on a first transversely extending weld seam and end with their second end at a certain spacing relative to the next transversely extending weld seam. The transverse cut also extends between the second end and the spaced next transversely extending weld seam. Such an arrangement is particularly advantageous when the upper film and the lower film are separate in themselves and are only connected by the weld seams at the longitudinal edges. More specifically, in that case the interruptions in the weld seams extending in the longitudinal direction give rise to transverse strips in which the upper and lower films are unconnected over their entire width. A cutting apparatus can then be particularly easily introduced into those transverse strips in order to produce the transverse cut through the upper film. In that respect, a flap which can be freely pivoted open at its edges is advantageously formed.

In addition the plastic strip may have markings which form codings for indicating the position of the weld seams and/or for indicating the film thickness and/or for indicating the film width. Markings for indicating the position of the weld seams eliminate expensive synchronisation, which would otherwise be required, for the apparatus for the production of filling bodies. The markings are preferably in the form of stamped-out openings but they could also be printed on, in an equally preferred fashion. In addition markings with items of coded information about the nature of the plastic tubes can be printed on or stamped out. In that way an apparatus for filling the plastic tubes according to the invention can detect the nature of the film just being introduced into the apparatus (for example film thickness, material, dimensions) and thus automatically adapt various operating parameters such as for example the welding time and temperature, the filling amount or filling time, the speed of transportation movement, and transportation distances and so forth.

The markings are preferably arranged on a line with the perforations or also in the immediate proximity thereof and are preferably stamped out in production of the tube by the same tool which also forms the perforations so that there is no need for an additional working operation.

In addition (preferably in the region of the transversely extending perforations and at least in the proximity of the longitudinal edges), there can be stamped-out openings for the engagement therein of a bar for further transportation of the tube. In that way the plastic tube can be easily passed through an apparatus.

The invention further concerns a gas-filled filling body for the packaging of articles, which is characterised in that it has been produced from a plastic tube of the kind discussed hereinbefore. Preferably a gas-filled filling body of that kind can contain an article to be packaged (individual article or solid/fluid filling material or loose bulk material) together with a defined amount of air. An article which is enclosed in the filling body in that way is optimally protected from shocks and vibration. The article can be removed at any time again when required by cutting the filling body. Disposing an article in the filling body is to be particularly well implemented when using the plastic tube according to the invention as it has a wide transverse cut, by way of which the article can be introduced.

The amount of air which is additionally enclosed in the filling body with the article to be packaged can be adapted to the respective packaging task involved. If completely inflated filling bodies are not wanted, then, after introduction of the articles and shortly before the welding operation, a predetermined part of the injected air can be urged out again by a stripping device. Subsequently allowing air to be discharged in that way affords the advantage that the operation of introducing the articles into the completely inflated filling bodies takes place particularly easily, with the volume of the finished filling bodies being reduced in relation thereto. The article is protected during transportation by the surrounding air. The air cushions which are formed in that way and which are filled with an article can be introduced for example in the form of a continuous web in a meander configuration into a cardboard box.

The invention further concerns a process for the production of a plastic tube of the above-discussed kind, wherein

• • a double layer is formed from an upper film and a lower film, which can be effected in particular by laying a full tube flat;
  • the weld seams extending in the transverse direction which delimit the individual inflatable pockets are produced;
  • at least one through hole is stamped through the upper film and the lower film; and
  • a cutting tool is introduced into said hole into the space between the upper film and the lower film and the upper film is thereby cut in the transverse direction to produce the transverse cut in the plastic tube.

The above-outlined process makes it easily possible for the desired transverse cut through the upper film to be produced. Preferably the individual steps of the process are executed in the specified sequence, but in that respect it is also possible in particular for the operation of producing the weld seams in the transverse direction to be effected after the stamping operation or production of the transverse cut.

In an alternative process for the production of a plastic tube according to the invention which is advantageously combined with the above-specified process the following steps are carried out:

• • a double layer comprising an upper film and a lower film separate therefrom is formed, wherein the upper film and the lower film can be produced for example by cutting a full tube at two sides in the longitudinal direction. Preferably in that case one of the films (for example the upper film) is narrower in dimension than the other film (lower film) so that the wider film projects somewhat at both longitudinal edges of the plastic tube and can thus be engaged separately at those edges for transportation purposes;
  • the upper film and the lower film are welded together by weld seams extending in the longitudinal direction in the region of the longitudinal edges.

The connection of the longitudinal edges by way of weld seams has the advantage that they lead to stabilisation of the resulting plastic tube and thus counteract the destabilising effect of the transverse cut.

In accordance with a development of the last-mentioned process the weld seams extending in the longitudinal direction are so effected that they have interruptions, wherein the upper film is cut at the location of those interruptions in the transverse direction to produce the transverse cuts. That interrupted configuration of the weld seams extending in the longitudinal direction has the advantage of affording transverse strips in which the upper film and the lower film are unconnected. A tool for cutting open the upper film can be particularly easily introduced into those transverse strips, while in addition a flap which is free at the edges is afforded by the transverse cut.

The invention further concerns a process for the production of gas-filled filling bodies comprising the following steps:

• • a) providing a prefabricated plastic tube of the kind described hereinbefore;
  • b) injecting air or another filling gas into each pocket through the gas filling opening which is formed by the transverse cut in the upper film of the plastic tube, and
  • c) gas-tight welding of the gas filling opening of the gas-filled pockets.

The specific configuration of the plastic tube used means that such a process can be very advantageously carried into effect. In particular the symmetrical effect of inflation and welding means that the plastic film no longer has a tendency to run out of its direction of transportation movement.

In the foregoing process the plastic tube, in the second processing step b), in injection of the filling gas, is preferably guided in a bend which faces away from the upper film and which typically can be 90°. Such a bend configuration causes the flaps formed by the transverse cut to flap open so that the filling opening is ‘automatically’ accessible for the operation of injecting the filling gas.

In accordance with a further development of the process prior to the welding operation in step c) an article to be packaged is introduced into the pocket which is to be inflated or which is already inflated. The subsequent welding operation provides that that article is enclosed in the pocket and thereby afforded optimum protection.

The invention further concerns an apparatus for carrying out the above-depicted process, characterised by the following components:

• • a holder for a supply of tube;
  • a transport device for transporting the tube through the apparatus;
  • a gas filling device having a nozzle with which air or another filling gas can be injected into the gas filling openings of the pockets; and
  • a welding device having a welding tool with which the gas filling openings of the pockets are gas-tightly closable with a weld seam extending in the transverse direction of the tube,
  • wherein at the gas filling device the transport device is of a configuration which bends away from the upper film.

In order to minimise possible leakage of filling gas the gas filling device may preferably have hold-down means which, during the introduction of the gas, press the flap of the upper film, which is formed by the transverse cut, against the gas filling device.

The apparatus may also have detection means for markings on the plastic tube, by which the machine speed and/or the gas filling amount and/or the welding time can be controlled. It is thus possible, by means of such devices, to fill plastic tubes prefabricated in different ways, in the apparatus, in which respect it can be automatically adapted to the respective optimum conditions.

The transport device of the apparatus can cyclically transport the plastic tube. In other words, the filling operation and the welding procedure each take place when the tube is stationary and the tube is then further transported by a pocket length.

It is particularly preferable nevertheless if the plastic tube is continuously moved past the gas filling device and the welding device. Such a mode of operation generally allows a greater production output, while the complication and expenditure in respect of control systems can be kept lower by possibly eliminating the cyclic control.

The invention is described in greater detail hereinafter by way of example with reference to the Figures in which:

FIG. 1 shows a cross-section through the plastic tube of FIG. 2 taken along line I-I,

FIG. 2 is a plan view of a first embodiment of a plastic tube according to the invention which is produced from a laid-flat full tube,

FIG. 3 is a longitudinal section through the plastic tube of FIG. 2 taken along line III-III,

FIG. 4 shows a view on to the plastic tube of FIG. 2 after welding of the inflated pockets,

FIG. 5 shows a cross-section through the plastic tube of FIG. 4 taken along line V-V, showing a pocket which has just been inflated as well as an inflated and welded pocket,

FIG. 6 shows a view on to and a cross-section and a longitudinal section of a second embodiment of a plastic tube with welded longitudinal edges, and

FIG. 7 shows a view on to and a cross-section and a longitudinal section of a third embodiment of a plastic tube with welds interrupted in pocket-wise manner at the longitudinal edges and in the central region.

FIGS. 1 through 5 show a first embodiment of a plastic tube 1 according to the invention, which is prefabricated for easier manufacture of gas-filled filling bodies for packaging purposes. The plastic tube 1 is produced starting from a laid-flat full tube, having an upper film 2 and a lower film 3 which are connected together at their two longitudinal edges 4 and 6.

In the transverse direction the plastic tube is subdivided by pairs of weld seams 5 consisting of a first weld seam 5a and a second weld seam 5b into inflatable pockets 7. Disposed between the weld seams 5a, 5b of a pair 5 thereof is a perforation 9 which extends transversely from the longitudinal edge 4 to the longitudinal edge 6 and along which the individual pockets 7 or later the gas-filled filling bodies 7′ can be separated from each other by being torn apart.

The prefabricated plastic tube 1 also has a transverse cut 12 extending in the transverse direction, through the upper film 2. That transverse cut 12 forms a filling opening 8 (FIG. 3), by way of which a filling gas can be injected into the pocket 7 between the upper film and the lower film. The transverse cut is preferably already present in the prefabricated film but it may also only be formed therein in the course of filling by a filling apparatus.

Provided at the two ends of the transverse cut 12 are preferably short incisions 10 extending in the longitudinal direction, thereby affording a flap 11 which can be pivoted open.

The operation of producing the transverse cuts 12 is preferably effected in such a way that firstly holes 10 are stamped through the upper film and the lower film, and then a cutting tool can be introduced through the holes 10 for cutting the upper film in the transverse direction.

FIGS. 4 and 5 show the plastic tube 1 during the operation of filling the pockets 7 with a filling gas which is injected into the pockets 7 through the filling opening 8. In this case, unlike the situation shown in FIG. 5, the plastic tube 1 can advantageously be diverted by way of a bend of for example 90° so that the detached flap 11 flaps open of its own accord by virtue of retaining its direction.

FIG. 5 also indicates that, besides the filling gas, an article 15 to be packaged (individual article or loose material) can also be introduced into the filling body, whereby it is packaged in such a way as to enjoy optimum protection. The operation of introducing the article is preferably effected at the moment at which the plastic tube 1 is deflected through a 90° bend so that the article can be ‘thrown’ into the pocket which is formed in that way, due to the effect of the force of gravity. Subsequently or at the same time the pocket is filled with a defined volume of air and then welded. In that way the articles—for example filigree glass pieces—are protected by an air cushion, in which case the web of air cushions issuing from the machine can be transported without any problem and can later be subjected to further processing by machine; in other words, the film web can be later cut open in a machine, in which case the articles can be individually removed. Alternatively, in the situation where a smaller volume is wanted for the air cushion pockets, it is also conceivable that, after the articles have been introduced into the pockets and prior to the welding operation, a part of the air can be removed from the pockets in order in that way to afford a smaller transportation volume.

FIG. 4 shows the weld seams 13 which extend in the transverse direction and which are produced after the injection of the filling gas. That can be effected for example in a suitable apparatus by a kind of flap with a heating wire dropping down and welding the upper film to the lower film. In that case (looking at FIG. 4) the weld seams 13 must be disposed below the longitudinal cuts 12 and the holes 10 which are stamped out for that purpose, in order to close off a corresponding pocket space gas-tightly therearound.

The gas-filled and completely sealed, finished filling bodies 7′ can then be separated from each other along the transversely extending perforations 9.

In the alternative embodiment of a plastic tube as shown in FIG. 6, in contrast to that shown in FIGS. 1 through 5, the two longitudinal edges are connected to each other (additionally or exclusively) by weld seams 14 and 16 respectively. Weld seams of that kind in the longitudinal direction contribute to stabilisation of the plastic tube and thus counteract the slightly destabilising effect of the transverse cuts.

FIG. 7 shows a modification of the embodiment of FIG. 6. In this case the upper film 2 and the lower film 3 are again connected by weld seams 24 and 26 respectively which extend in the longitudinal direction, but in this case they are not continuous but each only extend from a first transversely extending weld seam 5b as far as a spacing from the next transversely extending weld seam 5a. In that case, the transverse cut 12 through the upper film 2 is between the last-mentioned weld seam 5a and the end of the weld seams 24 and 26.

In addition in the embodiment shown in FIG. 7 the lower film 3 is somewhat wider than the upper film 2 so that it projects somewhat at both sides at the longitudinal edges 4 and 6 respectively. The lower film 3 can be engaged and guided at those projecting portions, by a suitable apparatus.

It can also be seen from FIG. 7 that arranged at the center of the plastic tube 1 are further weld seams 21 and 22 which extend in parallel relationship in the longitudinal direction and between which is provided a perforation 20 which is continuous in the longitudinal direction. That divides the plastic tube into two in the longitudinal direction, so that respective mutually juxtaposed inflatable pockets 7a, 7b are formed.

Claims

1. A plastic tube (1) for the production of gas-filled filling bodies comprising:

an upper film (2) and a lower film (3) said upper film and said lower film being gas-tightly connected together in mutually superposed relationship at a first respective longitudinal edge (4) and being welded together to form inflatable pockets (7, 7a, 7b) in the transverse direction by gas-tight weld seams (5a, 5b) arranged at a spacing relative to each other, said upper film and said lower film (2, 3) being connected together continuously at a second respective longitudinal edge (6) and

said upper film (2) having a transverse cut (12) in the transverse direction.

2. A plastic tube as set forth in claim 1 wherein said weld seams extending in the transverse direction are arranged in pairs, wherein provided between said weld seams (5a, 5b) of each pair (5) thereof is an intermediate space in which a perforation (9) through both films extends in the transverse direction.

3. A plastic tube as set forth in claim 1 wherein said transverse cut (12) ends at a spacing relative to the longitudinal edges (4, 6) and that incisions (10) are arranged at its ends in the longitudinal direction.

4. A plastic tube as set forth in claim 1 wherein weld seams (21, 22) are provided extending in the longitudinal direction and said weld seams (21, 22) are arranged in pairs and between said pairs is provided a perforation (20) extending in the longitudinal direction.

5. A plastic tube as set forth in claim 1 includes longitudinal edges connected by weld seams (14, 16, 24, 26).

6. A plastic tube as set forth in claim 5 wherein said weld seams (21, 22, 24, 26) extending in the longitudinal direction comprise portions having a first end respectively disposed on a first transversely extending weld seam (5b) and a second end is at a spacing relative to a next transversely extending weld seam (5a), wherein said transverse cut (12) extends through the upper film between said second end and said next weld seam (5a).

7. A plastic tube as recited in claim 1 includes a gas-filled filling body (7′) containing an article (15) to be packaged.

8. A process for the production of a plastic tube comprising the steps of:

forming a double layer from an upper film (2) and a lower film (3);

producing weld seams (5a, 5b) in the transverse direction;

stamping at least one hole (10) through the upper film (2) and the lower film (3); and

providing a cutting tool into said at least one hole and cutting said upper film (2) in the transverse direction to produce a transverse cut (12).

9. A process for the production of a plastic tube as set forth in claim 8, wherein the step of forming a double layer includes the steps of providing one of said upper films (2) narrower than said other lower film (3); and welding said upper film (2) and said lower film (3) together by weld seams (14, 16, 24, 26) extending in the longitudinal direction.

10. A process as set forth in claim 9 includes providing interruptions in said weld seams (24, 26) extending in the longitudinal direction at the level of which the upper film (2) is cut in the transverse direction to produce the transverse cuts (12).

11. A process for the production of gas-filled filling bodies (7′) comprising the steps:

a) providing a prefabricated plastic tube (1) having an upper film (2) and a lower film (3); said upper film and said lower film being gas-tightly connected together in mutually superposed relationship at a respective first longitudinal edge (4) and welded together to form inflatable pockets (7, 7a, 7b) in a transverse direction by gas-tight weld seams (5a, 5b) arranged at a spacing realive to each other; said upper film and said lower film being connected together continuously at a second respective longitudinal edge (6) and said upper film (2) having a transverse cut (12) in the transverse direction;

b) injecting air or another filling gas into each said inflatable pocket (7, 7a, 7b) through a gas filling opening (8) formed by said transverse cut (12) in said upper film (2) of the plastic tube (1), and

c) gas-tight welding of the gas filling opening (8) of the gas-filled pockets (7).

12. A process as set forth in claim 11 wherein the injecting step includes the step of guiding the air or another filling gas into a bend facing away from the upper film (2).

13. A process as set forth in claim 11 includes the step, prior to the welding operation in step c) introducing an article to be packaged (15) into one said pocket (7).

14. An apparatus for carrying out a process for the production of gas-filled filling bodies (7′) comprising:

a holder for a supply of tube;

a transport device for transporting the tube through the apparatus;

a gas filling device having a nozzle for injecting air or another filling gas into a gas filling openings (8) of a plurality of pockets (7, 7a, 7b); and

a welding device having a welding tool for welding said gas filling openings (8) of said pockets (7, 7a, 7b) gas-tightly closable with a weld seam (13) extending in a transverse direction of the tube,

wherein at said gas filling device, said transport device bends away from the upper film.