METHOD FOR PRODUCING PACKAGING UNITS IN A TUBULAR BAG-MAKING MACHINE

Abstract

The invention relates to a method for manufacturing packaging units (20) in a tubular bag forming, filling and sealing machine, which method contains vertically conveying disk-shaped products (11), which lie one above the other in portion stacks (10), and wrapping them with a film web being conveyed parallel to the products by means of a film take-off device, wherein the film web, in order to form a film tube (12), is provided with a longitudinal sealed seam by means of a longitudinal sealing device and subsequently with transverse sealed seams (18) above and below the portion stack by means of a transverse sealing device (14) being driven by a drive device independently of the film take-off device and moving in the same direction as the film web while the sealing device contacts the film web for sealing purposes, the transverse sealing device carrying out a vertical movement relative to the film tube in the direction opposite the conveying direction of the film tube while the sealing device contacts the film tube for sealing purposes.

Description

The invention relates to a method for manufacturing packaging units in a tubular bag forming, filling and sealing machine, which method contains vertically conveying disk-shaped products, which lie one above the other in portion stacks, and wrapping them with a film web being conveyed parallel to the products by means of a film take-off device, wherein the film web, in order to form a film tube, is provided with a longitudinal sealed seam by means of a longitudinal sealing device and subsequently with transverse sealed seams above and below the portion stack by means of a transverse sealing device being driven by a transverse sealing drive device independently of the film take-off device and moving in the same direction as the film web while the sealing device contacts the film web for sealing purposes.

When manufacturing tubular bags, the film web initially being fed to a molding shoulder as a flat element is shaped, by means of the molding shoulder, into a plastic tube which has an overlapping longitudinal joint, and which serves for receiving products being conveyed to the film web in a fashion parallel thereto and lying one above the other in a portion stack. After the longitudinal joint has been sealed by means of a longitudinal sealing device, transverse sealed seams are formed by means of a transverse sealing device for manufacturing a packaging unit that in each instance receives one or more portion stacks lying one behind the other in a row in the conveying direction.

With the disk-shaped products lying one above the other in a portion stack, it has in particular in the context of cookies and similar items, which have a cream filling between sandwich cookies, shown that tensile stresses arise in the film web due to the formation of the transverse sealed seams, which tensile stresses give rise to radial stresses being exerted on the cookies, causing a wedged pitch of the sandwich cookies in the cream filling that is often still warm and soft at the time of manufacturing the packaging units and thus causing an undesired deformation of the product.

One possibility of avoiding this undesired wedge effect, is to maintain a sufficiently large space between the portion stacks being arranged in the film tube, in the conveying direction of the film web, when creating the transverse sealed seams, such that the tensile stresses that arise when creating the transverse sealed seams are reduced and thus the radial stress acting on the cookies also become correspondingly smaller. However, a corresponding reduction of the filling degree of the individual packaging units and an increase in the consumption of film web are connected with this, such that, apart from a deterioration in the productivity of the production device, an increase in the manufacturing costs is also the result.

The present invention is therefore based on the task of proposing a method for manufacturing packaging units in a tubular bag forming, filling and sealing machine, which method allows for packaging that is gentle on the product at a high productivity of the production facility.

This task is solved by a method having the features of claim 1.

In the method in accordance with the invention, the transverse sealing device carries out a vertical movement relative to the film tube in the direction opposite the movement direction of the film tube while the sealing device contacts the film tube for sealing purposes.

Owing to the fact that the transverse sealing device contacts the film tube for sealing purposes, an accumulation of the film tube results from the superposition of the vertical relative movement, which takes place in the direction opposite the movement direction of the film tube, the accumulation being located in the region between the transverse sealed seam and the portion stack being arranged above the transverse sealed seam. Said accumulation leads to the film tube remaining substantially free of tensile stresses in the region of the lower end of the respective packaging unit and to a limp bag gusset being formed.

Hereby, it is ensured that by forming the sealing in the region of the transverse sealed seam, tensile stresses are not induced in the film tube, which stresses would give rise to undesired lateral forces being exerted on the lower end of the portion stack.

Hereby, it becomes even possible to package easily deformable cookies, which means in particular sandwich cookies being provided with a cream filling, immediately subsequently to the baking process, without making sure that the cream filling is stable enough prior to packaging by cooling the cookies in between.

Since the film tube is preferably cut through in the region of the transverse sealed seam, simultaneously to the transverse sealed seam being formed, it is avoided that, due to the accumulation, increased tensile stresses can arise in the region of the upper packaging end of the packaging unit being arranged below the transverse sealing device.

It proves to be particularly advantageous if the relative movement of the transverse sealing device is effected by means of a retardation of the vertical movement of the transverse sealing device since the film web can thus be conveyed continuously and at a constant speed in the tubular bag forming, filling and sealing machine by means of the film take-off device and the required relative movement can thus be effected via a corresponding kinematic control of the transverse sealing device alone.

If the retardation of the vertical movement of the transverse sealing device, in a final phase of the contacting for sealing purposes, is effected subsequently to an at least partially material connection of film web portions that rest against one another, via the contacting for sealing purposes, a sufficiently high heat transfer into the film tube can be effected in order to exploit a small plastic deformation of the film tube for supporting the formation of a limp bag gusset of the packaging unit.

In order to preclude an application of force on the portion stack in the conveying direction of the film tube owing to the vertical relative movement of the transverse sealing device, it is advantageous if the movement distance s that is covered by means of the relative movement of the transverse sealing device is smaller than the space a between the transverse sealing device and the portion stack being arranged above the transverse sealing device.

In the following, a preferred embodiment of the invention is explained with the aid of the drawings.

In the figures:

FIG. 1: shows a transverse sealing device in a starting phase of contacting the film tube for sealing purposes;

FIG. 2: shows the transverse sealing device being illustrated in FIG. 1 in a final phase of contacting the film tube for sealing purposes.

FIG. 1 shows a lower end of a film tube 12 being formed in a tubular bag forming, filling and sealing machine for wrapping disk-shaped products 11 lying one above the other in a portion stack 10. The film tube 12, by means of a film take-off device not being illustrated in more detail in FIG. 1, is conveyed in the vertical conveying direction 13 to a transverse sealing device 14, which comprises two sealing tools 15, 16 being driven via a movement transmission that is not illustrated in more detail, such that the same rest, with sealing surfaces 17, against the film tube 12 being arranged between the sealing tools 15, 16 while contacting the film tube for sealing purposes, said contact being illustrated in FIG. 1.

Outside of the sealing phase being illustrated in FIG. 1, the sealing tools 15, 16 are in a portal position which is illustrated in FIG. 1 in dash and dot lines, and in which position the sealing tools 15, 16 are moved apart, such that the film tube 12, with the products 11 being received therein, can pass through the sealing tools 15, 16 of the transverse sealing device 14.

The movement drive of the sealing tools 15, 16 is formed such that the sealing tools 15, 16, in their sealing position being illustrated in FIG. 1, are moved, by means of a drive device not being illustrated in more detail, in the conveying direction 13 of the film tube 12 while contacting the film web for sealing purposes. Afterwards, the sealing tools 15, 16 are moved back into the portal position and around the movement path being performed in the conveying direction 13 during contacting for sealing purposes in the direction opposite the conveying direction 13 of the film tube 12, in order to be transferred, in a subsequent sealing process for creating a transverse sealed seam 18, into the sealing position being illustrated in FIG. 1 again.

In the sealing position, the film tube 12 is cut through in the region of the transverse sealed seam 18 by means of a cutting device 19 being integrated into the transverse sealing device, such that a packaging unit 20 being defined in its length by two adjacent transverse sealed seams 18 is torn off from the film tube 12.

The products 11 being illustrated in FIG. 1 by way of example are sandwich-like cookies, which receive a cream filling 23 between surrounding cookies 21 and 22. At the time of the manufacturing of the packaging units 20, the cream filling 23 of the products 11 being fed to the tubular bag forming, filling and sealing machine immediately after a baking process is still relatively soft, such that radial stresses acting on the sandwich cookies 21, 22 can easily lead to a deformation or to the cream filling 23 oozing out of the product 11.

As it can be comprehended with the aid of FIG. 1, owing to the sealing process, tensile stresses arise in the film tube 12 in the region of a bag gusset 24 being formed between the transverse sealed seam 18 and the portion stack 10 of the products 11, which tensile stresses give rise to radial stresses F acting on a product boundary region 25 being opposite to the transverse sealed seam 18, said stresses being able to cause a wedged pitch of the sandwich cookies 21, 22 with respect to each other when a critical size has been reached and if the cream filling 23 is still soft, and thus being able to cause a corresponding product deformation.

As it is illustrated in FIG. 2, the sealing tools 15, 16 of the transverse sealing device 14, in a final phase of the contacting for sealing purposes, carry out a relative movement subsequently to an at least partially material connection of film web portions 28, 29 that rest against one another, for forming the transverse sealed seam 18, said relative movement having a movement path s, in order to move the sealing tools 15, 16 from the starting phase of the contacting for sealing purposes being illustrated in FIG. 2 in dash and dot lines in relation to the film tube 12 in the direction opposite the conveying direction 13 of the film tube 12.

In the present case, said relative movement is carried out by a retardation of the transverse sealing device 14 being moved in the same direction as the film tube.

As it becomes clear from FIG. 2, the formation of tensile stresses in the bag gusset 24 and of radial stresses F that reach the critical size can be prevented in that, owing to the relative movement of the transverse sealing device 14, a limp form of the bag gusset 24 is achieved.

As it can further be seen from FIG. 2, the movement distance s being covered by means of the relative movement of the transverse sealing device 14 is smaller than the space a between the transverse sealing device 14 and the portion stack 10 being arranged above the transverse sealing device 14.

In order to support the bag gusset 24 being formed in a defined fashion at the transverse sealed seam 18, in the case of the illustrated exemplary embodiment, folding pushers 27, 28 are provided in each instance above and below the transverse sealing device 14, being pivotable into the film tube 12 at an angle to the conveying direction 13 of the film tube 12, and allowing for a defined formation of a gusset fold, such that the film web portions lying opposite to one another, in the region of the bottom gusset, lie one above the other in a fanfold fashion and such that a correspondingly defined formation of the transverse sealed seams is possible.

Claims

1. A method for manufacturing packaging units in a tubular bag forming, filling and sealing machine, said method comprising: vertically conveying disk-shaped products lying one above the other in portion stacks;wrapping the portion sacks with a film web conveyed parallel to the products by a film take-off device;forming a longitudinal sealed seam in the film web to form a film tube using a longitudinal sealing device, said film tube moving in a conveying direction; andforming transverse sealed seams in the film tube above and below each portion stack using a transverse sealing device driven by a drive device independently of the film take-off device and moving in the same direction as the film tube while the sealing device contacts the film web to form each transverse sealed seam, wherein the transverse sealing device moves vertically relative to the film tube in a direction opposite the conveying direction of the film tube while the sealing device contacts the film tube to form each transverse sealed seam.

2. The method according to claim 1, in which the relative movement of the transverse sealing device is effected by means of a retardation of the vertical movement of the transverse sealing device.

3. The method according to claim 2, in which the retardation of the vertical movement of the transverse sealing device, in a final phase of the contacting for sealing purposes, is effected subsequently to an at least partially material connection of film web portions that rest against one another.

4. The method according to claim 1, in which the movement distance s that is covered by the relative movement of the transverse sealing device is smaller than the space a between the transverse sealing device and the portion stack of the products being arranged above the transverse sealing device.