HK1100029B - Device and process for applying a weld seam as well as film bag - Google Patents

Description

The invention relates to a device and a method for attaching a welding suture to a film bag and to the film bag itself.

Foil bags are known as packaging for liquids or pasteous masses. For example, beverages, pet foods, creams, paints, soaps, etc. are packaged in foil bags. Such foil bags can be, for example, standing floor bags, which are composed of two side foils and one floor foil.

The various films are welded together at the respective edges, either by hot-welding or by ultrasonic welding.

The following models are available: EP 1 088 760 A2, EP 1 127 794 A2 and EP 1066 951 A2.

US4,534,818 shows a process and apparatus for ultrasonic welding and DE 1,604,580 shows a process and apparatus for the manufacture of all-sided bags.

The welds occasionally have small unwanted leaks.

The present invention is therefore intended to create a device and a method for attaching a welding joint to a film bag which has improved welding joints.

This task is solved by a device as claimed in claim 1 or 8 and by a process as claim 9.

The welding joint is formed by an ultrasonic hammer and an anvil. The ultrasonic hammer can be used to introduce ultrasonic waves into the film material, which causes it to melt locally. To effectively couple the ultrasonic waves from the ultrasonic hammer into the film material, the film material can be clamped between the ultrasonic hammer and an anvil.

The amber has a slit on its side facing the ultrasonic hammer to fit the film bag between the slit and the ultrasonic hammer.

In the case of anvils, the opening must have at least one groove, for example a groove, parallel to the opening or the weld joint.

In the area of the bulge of the anvil, the film material can melt under ultrasonic action and be pushed out of this area by the pressure between the ultrasonic hammer and the anvil.

The arrangement of the groove in the opening allows the weld to be welded with four such seals, which thus lead to a particularly good and safe seal.

The two sealing cones that form at the edges of the depression can also grow together in the area of the depression, so that a single sealing cone or rather a sealing zone is effectively created here, so that a total of three sealing cones can be produced.

To avoid excessive bulging of the film or contact with the unmelted film material under additional pressure, the depth of the depth of the film is advantageous in comparison with the height of the projection.

For good weld sealing results, the depth of the seam shall be about 25 to 50% and preferably about 30 to 35% of the width of the lead.

The amber is preferably not fixed, but tiltable. Here, a tilt of at least 2 axes is advantageous. The axes do not have to pass through the amber itself (which is also possible), but can also pass outside the amber.

The advantage is that the amber is stored in such a way that it is pre-tensioned in the direction of the ultrasonic hammer, preferably by 2 pressure elements such as springs, rubber elements, or the like.

These bearings and pre-tensionings allow a uniform pressure to be ensured along the welding joint between the anvil and the ultrasonic hammer, which is advantageous for the formation of a uniform welding joint along the welding joint length.

For a good alignment of the anvil, it is advantageous that the two pressure elements strike at the ends of the anvil.

To further increase the reliability of the sealing of the weld, more than a single groove can be provided, with these grooves running essentially parallel to each other, thus achieving an even higher number of sealing pins than three or four, which results in an even better sealing effect.

A device in which several film bags can be welded together is advantageous, allowing high throughput rates at the same clock rate and minimal construction effort, since the various mechanical devices can be used together in the different welding equipment.

The method involves clamping the part of a film bag to which a weld is to be attached between a ledge and an ultrasonic hammer and attaching the weld by ultrasonic impact with the ultrasonic hammer, with at least a deepening of the ledge.

The film bag has a welding joint with at least two welding zones and at least three or four sealing pins.

The figures illustrate the advantages of the invention. Figure 1Schematic views of a film bagFigure 2Schematic intersectional drawings of the device and the film bagFigure 3a three-dimensional schematic representation of the amboss.

The three-dimensional schematic representation of a film bag 1 is shown in Figure 1a. The same film bag 1 is shown in interfaces in Figure 1b. The film bag 1 has two side foils 3a and 3b and a floor film 5. The floor film 5 is folded here and welded at the bottom ends with the edges of the side foils 3a and 3b. The side foils 3a and 3b are welded together at the edges of the film bag 1 shown in Figure 1a and left. These welds of the side foils 3a, 3b on the lateral edges and welds with the floor film 5 can also be produced by thermal welding by the ultrasonic weld described here.

The film bags 1 can be made open at the top end 4 and not yet closed by a welding seam 2 which allows the film bags 1 to be filled through the top end 4 and closed at the top end 4 by the welding seam 2 after filling.

The most likely problem of leakage is the welding of the top end 4 after filling, since there may be contamination on the inside of the bag which prevents a tight weld.

In Figure 2a, the top end 4 of a film bag 1 is shown. In the region 4 the two side films 3a and 3b meet. The side films 3a and 3b shown here are composed of at least 2 layers 6a, 7a and 6b, 7b. The layer 6a, 6b can itself contain different layers. It can include, for example, an aluminum foil and a non-welding plastic. The layer 6a, 6b can also contain a decorative pattern that is visible from the outside.

The two layers 7a, 7b of the two side films 3a, 3b are in direct contact with each other at the upper end 4, but they are not initially firmly connected.

The upper end of film bag 1 is shown wedged between an amboss 8 and an ultrasonic hammer 9. The amboss 8 has a protrusion 10 in contact with the upper end of film bag 1. The amboss 8 and the ultrasonic hammer 9 can be moved away from and onto each other, for example by moving and/or deflecting either the amboss 8 or the ultrasonic hammer 9 or both.

The ultrasonic hammer 9 is connected to an ultrasonic source which allows the ultrasonic hammer 9 to couple ultrasonic waves into the material of the film bag 1.

The width of the opening 10 is a width a and the height h. The opening 10 has a depth 11 which may be, for example, in the shape of a groove.

Instead of just one 11th hole, two, three or more can be made, and between them there is an elevation (not shown) which can be flat with the areas of the ledge outside the groove, or less or more elevated.

The ultrasonic pressure between the amber 8 and the amber 9 causes the molten material to flow out of this area (upper weld zone 12, 13) and forms dense layers in the 14a, 14b, 14c, 14d area. These dense layers bind the two seamless films together. The 6a, 6b and 6a layers of the amber are not allowed to adhere together on the same level of the amber, but they do not allow the molten or molten material to adhere to the same level of the amber 7a and 6a layer of the amber 9 (although the amber 6a and 7a layers of the amber 7a and 6a layer of the amber 9 allow the amber to adhere to the same level of the amber 6a layer of the amber).

The formation of four seals, all of which extend along weld 2 sections, has resulted in a particularly good sealing of this weld 2.

The use of several recesses can also produce more sealing wedges or welding zones, which allows for an even better sealing of the welding seam.

The seals in sections 14b and 14c can also come into contact with each other and form a single seal through a low depth t of the sealing 11 and/or a low width b. If the sealing 11 provides only a small amount of space, the molten material is pressurized into the sealing 11 area and occupies all the available space. This results in a particularly good adhesion between the non-melted areas of the side film 3a, 3b. This also applies in the case of several seals 10.

Figure 3 shows a schematic three-dimensional representation of an anvil 8 in its storage. On the front of anvil 8 the ledge 10 with the depth 11 can be seen.

The ambulation 8 is attached to pivot elements 16 with pivot axis 15 parallel to the forward 10 pivot.

The 10th ledge extends over the entire length or most of the length of the 8th embankment.

The elements 16 are in turn held to an element 17 which is itself rotatable, the rotation axis 14 around which the element 17 is rotatable being perpendicular to the rotation axis 15.

The amber 8 can thus be tilted with little mechanical effort around both axis 14 and axis 15.

The amphitheater is equipped with a spring, which is attached directly to the amphitheater. The amphitheater is also equipped with a spring, which is attached directly to the amphitheater.

The bending of the ambulation 8 around the pivot axis 15 is preferably limited in the direction of the ultrasonic hammer 9 and this makes it possible to separate the ambulation 8 from the ultrasonic hammer 9 to create a gap between them into which a film bag 1 can be inserted. When the ambulation 8 and the ultrasonic hammer 9 are then brought back together, the foil bag 1 is clamped. A slightly further jointing causes the ambulation 8 to tilt around the pivot axis 15 in Figure 3 to the upper left, but at the same time the springs 18, 19 are stretched against the ultrasonic hammer 9 on the left.

Above the ultrasonic hammer 9 there may be a spring bracket, for example, made of spring steel, which can be used to press the top end of the film bag 1 protruding above the protrusion 10 against the amboss 8 to secure the bag for clamping between the amboss 8 and the ultrasonic hammer 9.

The bending of the anvil 8 around the axis 14 makes it possible to compensate for slight inaccuracies in the positioning of the anvil 8 or the ultrasonic hammer 9 or the film thickness of the side foil sides 3a, 3b. This distributes the pressure generated by the spring elements 18 and 19 evenly over the entire width of the anvil 8 or along the weld joint 2.

The advantage of the devices shown in Figure 3 is that several are arranged side by side, which allows the same supports or conveyors to weld several foil bags 1 side by side at the same time.

Preferably, a single tilting-stock amber 8 is provided for each film bag 1, but an amber 8 may also be provided for two or more film bags.

Claims (9)

1. Device for applying a weld seam (2) to a foil bag (1) comprising:

   - an ultrasound hammer (9) and

   - an anvil (8) with a welding face directed towards the ultrasound hammer (9) which has a longitudinally extending projection (10) so that the foil material (3a, 3b, 6a, 6b, 7a, 7b) of the foil bag (1) can be clamped between the projection (10) and the ultrasound hammer (9),

   and the projection (10) has at least one depression (11) extending parallel with the projection (10), and the at least one depression (11) has a shorter depth (t) than a height (h) of the projection (10) across the welding face, characterised in that the at least one depression (11) has a width (b) which accounts for approximately 25 % to 50 % and more preferably 30 % to 35 % of the width (a) of the projection (10) and the anvil (8) is secured to pivotable elements (16) and the pivot axis (15) extends parallel with the projection.
2. Device as claimed in claim 1, characterised in that the anvil (8) can be tilted.
3. Device as claimed in claim 2, characterised in that the anvil (8) can be tilted about at least two axes (14, 15).
4. Device as claimed in one of claims 1 to 3, characterised in that at least two compression elements (18, 19) such as springs apply a force to at least two different points of the anvil (8), causing the anvil (8) to be biased in the direction of the ultrasound hammer (9).
5. Device as claimed in claim 4, characterised in that the two compression elements (18, 19) act approximately on the ends of the anvil (8).
6. Device as claimed in one of claims 1 to 5, characterised in that a spring clip is provided, by means of which the top end (4) of a foil bag (1) can be pressed against the anvil (8).
7. Device as claimed in one of claims 1 to 6, characterised in that two, three or more depressions (11) are provided in the projection (10), and the width of the depressions (11) together preferably accounts for approximately 30 % to 35 % of the width (a) of the projection (10).
8. Device for applying weld seams to foil bags, whereby several of the devices as claimed in one of claims 1 to 7 are disposed adjacent to one another and can be operated synchronously.
9. Method of applying a weld seam (2) to a foil bag (1) which is clamped between an ultrasound hammer (9) and an anvil (8), and the anvil (8) has a longitudinally extending projection (10) on a welding face directed towards the ultrasound hammer (9), and the foil bag (1) is provided with a weld seam (2) by means of ultrasound, and the projection (10) has at least one depression (11) extending parallel with the projection (10), and the at least one depression (11) has a shorter depth (t) than a height (h) of the projection (10) across the welding face, characterised in that the at least one depression (11) has a width (b) which accounts for approximately 25 % to 50 % and more preferably 30 % to 35 % of the width (a) of the projection (10) and the anvil (8) is secured to pivotable elements (16) and the pivot axis (15) extends parallel with the projection.