From an environmental viewpoint and cost considerations associated therewith, there are a growing number of objections to the use of chips of plastic material and shredded paper as filling material in packagings.

Known from the international applications O94/07678 and W091/12175 are methods and devices for filling with air small cushions which, individually or as a mutually adhered series,, can be used as filling material. After use the volume of these cushions can be reduced and the plastic material removed, for instance to be re-used.

A problem of this known device and method relates to the arranging of holes in sufficiently reliable manner in a tubular foil from which the cushions are made. It has been found in practice that many formed air cushions do not have a sufficient air filling, for example because during piercing of a hole two holes are pierced in the tube form, wherein the air will escape through the second hole. Furthermore, with the known device and method equipment is required for injecting air under pressure.

The present invention provides a method for manufacturing one or more cushions filled with air from a piece of tubular material, wherein a piston member is placed into the tubular material, a hole is pierced in the tubular member, the piston member and the tube member are moved and one or more weld seams are arranged in the tubular material. The present invention further provides a device for manufacturing one or more cushions filled with air from a piece of tubular material, comprising:

- a piston member which is placed into the tube form;

- piercing means for piercing one or more holes in the tube form; - moving means which engage on the piston member and cause the piston member to move together with the tube form; and

- welding means for arranging one or more weld seams in the tube form. Further advantages, features and details of the present invention will become apparent in the light of the following description of a preferred embodiment thereof with reference to the annexed drawing, in which: fig. 1 shows a partially broken away view in perspective of a first preferred embodiment of the present invention; fig. 2 shows an enlarged view of detail II of fig. 1; and fig. 3A-3E show schematic views of respective operative positions of the device shown in fig. 1.

A preferred embodiment of a device 1 according to the present invention comprises a frame 2 to which is fixed an annular plate 3. Further fixed to frame 2 is a lifting device 4 which serves to lift and lower a fork- like member 5. A piercing member 6, welding members 7 and 8 respectively, clamping means 20 and holding means 9, 25 are further arranged on frame 2.

In the method according to the present invention a piston member 10 comprising a stationary part 11 (fig. 2) and a movable part 12 is first of all inserted into a piece of tubular material M. The stationary part 11 is provided with a shoulder 13 which rests on the edge of the central opening in the annular plate 3. The stationary part 11 is also provided with a central bore in which can slide a hollow sliding rod 14 which is fixedly connected to the movable part 12. The movable part or plunger part 12 is further provided with a radial groove 15 in which debouches a channel 16 which

is arranged internally in the member 12 and connects onto the internal channel of the hollow sliding rod 14.

The operation of the device according to the present invention is described hereinbelow: From the starting position shown in fig. 3A the piercing member 6 is moved into the position shown in fig. 3B, preferably in a tangential direction along the groove 15, so that the outer end of the piercing member does not come into contact with plunger part 12. Piercing member 6 is then retracted and plunger 12 is moved upward using the fork member 5 to the position shown in fig. 3C and 3D. In this upward movement the tubular material M, for example of polyethylene or polyester, is also transported upward. Through the upward movement of plunger part 12 between the positions shown in fig. 3B and 3C, air is drawn in through the hole 19 pierced in the tube form. Clamps 21 and 22, which are movable in a manner not shown between the positions shown in fig. 3A, 3B, 3C and 3E on the one hand and the position shown in fig. 3D on the other, clamp the tube form in the position shown in fig. 3D against the cylindrical outer wall of plunger part 12. When welding members 7 and 8 respectively are moved toward each other air is thus prevented from escaping via the hole 19. In this way the air cushion C is formed, wherein a preceding hole is situated at the height of welding members 7, 8, and therefore between two successive air cushions C.

The plunger 12 is then moved downward as shown in fig. 3E, wherein pin member 9 is also moved to support 25 in order to ensure that, after the welding members 7, 8 have moved apart, the tube form M is held in place during the return movement of plunger part 12. During this return movement of plunger part 12 air is also supplied via the hollow sliding rod 14 through channel 16 in order to prevent an underpressure occurring above plunger part 12. Subsequent to the position shown in fig. 3E the device according to the present invention reaches

the position shown in fig. 3A and the cycle can be repeated.

During testing with the above described preferred embodiment of the present invention 50 air cushions per minute were produced with great reliability with negligible rejection of air cushions occurring and while, as will be apparent from the foregoing, no compressor was required to inject air under pressure into the tube form. If, as will be apparent to the skilled person from the annexed figures, use is made of compressed air to control the various components of the device, a much smaller compressor can suffice than that required for devices of the prior art, wherein this compressor also serves to supply air under pressure to an injector for injecting air into the tube form.

It will be apparent that many modifications and adaptations can be envisaged relative to the above described preferred embodiment of the present invention; the rights applied for are in no way limited by this above described preferred embodiment. The rights applied for are defined in the first place by the following claims.

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