Technical Field

The invention concerns the method for application of stiff tin tie closure (the so called secondary closure), acting on the shape memory principle, for a bag made of a packing film.

Background Art

The tin tie closures, acting on the shape memory principle, are used for secondary closing of film bags usually. According to the stiffness of the material of which these tin tie closures are made the tin tie closures can be divided into two groups:

1. The tin tie closures with the stiffness comparable to that of the wrapping film.

2. The tin tie closures with the stiffness the value of which is by one order higher than the wrapping film stiffness. The closure from this group is being denoted as the "stiff tin tie closure". In compliance with the location thereof on a film bag, these stiff tin tie closures can be placed either in the moving direction of the original film tube or perpendicularly to the moving direction of the original film tube in a vertical form fill seal packaging machine.

The tin tie closures, the stiffness of which is comparable to that of the wrapping film, are applied very easily relatively on a .flat wrapping film before its entry into a shaping device of a vertical form fill seal packaging machine.

The stiff tin tie closures cannot be applied in the above mentioned way because the high stiffness thereof prevents them from passing through the shaping device of a vertical form fill seal packaging machine. A well known method to apply stiff tin tie closures, acting with the shape memory principle, on film bags is based on a procedure according to which a film bag is shaped first in a vertical form fill seal packaging machine and then separated. Then a stiff tin tie closure, acting on the shape memory principle, is applied on said film bag. The bag is filled with goods either in a subsequent device after the stiff tin tie closure has been applied or in a vertical form fill seal packaging machine yet. The bag is closed either in a vertical form fill seal packaging machine or in a subsequent device. The disadvantage of the known method to apply the stiff tin tie closures, using the shape memory principle, is the necessity to use complicated devices which follow after the proper vertical form fill seal packaging machine. They are complicated because the individual shaped and separated film bags must be fixed in space again behind the vertical form fill seal packaging machine, with the stiff tin tie closure being applied afterwards. This is problematic even in case the bag has been filled in the vertical form fill seal packaging machine yet and further more if the bag has to be closed not only before in a subsequent device. Except of introducing high cost price and need of larger ground areas there are problems in precise locating the stiff tin tie closure on individual bag. The bags on which the tin tie closures are applied are standing usually, i.e. with a flat bottom. For non-folded bottom bags the known solution is even more complicated.

Disclosure of the Invention The substance of the invention consists in a method for application of a tin tie closure on a film tube in a vertical form fill seal packaging machine. In this method the film tube is led through the vertical form fill seal packagmg machine and the shaped film bag is filled with goods before being separated from the film tube. The film tube can be led through the vertical form fill seal packaging machine step by step or continuously. The stiff tin tie closure is applied on the film tube with its longer side in the direction which is perpendicular to the movement direction of the film tube. The stiff tin tie closure is applied in the space behind the shaping device i.e. before separating the bag from the film tube.

A variant solution consists in a method for application of an otherwise-oriented stiff tin tie closure. This variant method for application of the stiff tin tie closure on the film tube is made again so that the film tube is led through the vertical form fill seal packaging machine and the shaped film bag is filled with goods before being separated from the film tube. In this case the stiff tin tie closure is applied on the film tube with its longer side in the direction which is parallel with the film tube movement direction. The stiff tin tie closure is applied in the space behind the shaping device i.e. before separating the bag from the film tube.

With the stiff tin tie closure being applied on the film tube with its longer side in the direction which is parallel with the film tube movement direction, it can be applied under the longitudinal folding of the film tube. This is due to aesthetic reason especially nevertheless the strip, applied in this latent way, can show also better resistance against unintentional ungluing. It is advantageous if the separating jaws serve for separating as well as closing the film bag, filled with goods.

In the above mentioned methods for application of the stiff tin tie closure, acting on the principle of a shape memory, this closure can be applied on the film tube in the vertical form fill seal packaging machine, in the space behind the shaping device i.e. before separating the bag from the film tube. Among the advantages of this method it is that there is not any technically and spatially complicated and pretentious transport of individual finished bags from the output of the vertical form fill seal packaging machine into a subsequent applicator of stiff tin tie closures and also more precise location of stiff tin tie closures on film bags as well. The application is not conditioned due to shape of the film bag bottom. In the application method according to the invention the stiff tin tie closures can be applied both in perpendicular as in parallel direction with the film tube movement direction.

Brief Description of Drawings

The invention can be explained nearly by means of drawings of which

Fig. 1 shows a simplified functional diagram of the vertical form fill seal packaging machine with location of the applicator of the stiff tin tie closure to apply the closure perpendicularly to the film tube motion direction,

Fig. 2 shows the film bag with a folded flat bottom and the stiff tin tie closure, applied perpendicularly to the film tube motion direction,

Fig. 3 shows the film bag with the unfolded bottom and the stiff tin tie closure, applied perpendicularly to the film tube motion direction,

Fig. 4 shows the simplified functional diagram of the vertical form fill seal packaging machine with location of the applicator of the stiff tin tie closure to apply the closure in parallel with the film tube motion direction,

Fig. 5 shows the film bag with the stiff tin tie closure, applied in parallel with the film tube motion direction,

Fig. 6 shows the film bag with the stiff tin tie closure, applied parallelly with the film tube motion direction under the longitudinal folding of the film. Best Modes for Carrying Out the Invention

Example no. 1 In the production of a bag with a stiff tin tie closure the flat packing film I is shaped by passage through a shaping device 2 and welded into a film tube 9 afterwards. By means of an applicator 4 which is placed under separating jaws 3 a stiff tin tie closure 6 is applied on the film tube 9 which is closed yet on its bottom end in the shape of the film bag 5, said stiff tin tie closure 6 being applied with its longer side perpendicularly to the moving direction 15 of the film tube 9. Then the separating jaws 3 separate the filled film bag 5, including the stiff tin tie closure 6, from the film tube 9. At the same time it does not matter whether the bags 7 with a folded bottom 8 of the bags 10 with an unfolded bottom are produced. The exemplary realization can be seen on the Figs 1 to 3.

Example no. 2

In another example, in the production of the bag with the stiff tin tie closure, the flat packing film 1 is shaped by passing through the shaping device 2 and welded into the film tube 9 subsequently. The stiff tin tie closure 12 is applied on the film tube 9 by means of the applicator j l_ which is placed above the separating jaws 3, said stiff tin tie closure 12 being applied with its longer side in parallel with the movement direction 15 of the film tube 9. Then the separating jaws 3 separate the filled film bag 13, including the stiff tin tie closure 12, from the film tube 9. At the same time it does not matter whether the bags 7 with a folded bottom 8 of the bags 10 with an unfolded bottom are produced. The stiff tin tie closure 12 can be placed on the film bag either visibly or latently under a longitudinal folding 14.

The exemplary realization can be seen on the Figs 4 to 6.

Industrial Applicability

The method for application of stiff tin tie closure can be utilized in the field of packaging into film bags especially for small consumers in vertical tube packaging machines. The proper bags with the stiff tin tie closure can be used in packing of various kinds of small-piece or powdery goods, e.g. coffee beans or ground coffee, tea, feed for domestic animals etc. The closures for repeated closing and opening of the bag enable a final user to open the bag repeatedly, take out the packaged goods and close the bag again. In this way, the remaining content of a bag is prevented from being spilt and possibly from changing sensory properties or other properties of the bag content. The advantage of the stiff tin tie closure, acting on a shape memory principle, is its reliability.

List of Reference Numbers

1 - flat packing film

2 - shaping device

3 - separating j aws

4 - applicator

5 - film bag

6 - stiff tin tie closure

7 - folded-bottom film bag 8 - folded bottom

9 - film tube

10 - unfolded-bottom film bag

11 - applicator

12 - stiff tin tie closure

14 - longitudinal folding

15 - film tube movement direction