MEANS AND METHOD TO PROVIDE EMBOSSMENTS ON PACKAGING CONTAINERS .

Technical Field

The present invention concerns a packing machine in which sealed packaging containers or packages are formed from a packaging material web. In particularly it concerns means to form embossments on the packaging containers. It also concerns a method of processing the packaging material web.

Prior Art In the food industry liquid contents, such as milk or juice, are often filled in packaging containers, which are manufactured from a flexible, liquid-tight packaging material . The packaging material is normally a flexible packaging laminate which comprises a carrier or core layer of fi- bre material, e.g. paper, which is coated on each side with relatively thin layers of thermoplastic material, such as polyethylene. The packaging laminate may also include further material layers, such as barrier layers of metal or other barrier materials in order to provide improved pro- tection against light or oxygen when particularly sensitive products are to be packed.

In the manufacture of the packaging containers a packing or filling machine is normally used, which stepwise reforms a packaging laminate web into separate filled pack- aging containers. The packaging laminate is provided with a pattern of folds or crease lines to facilitate the forming of the packaging containers. The packaging laminate web is normally fed from a roll via a number of guide rolls to a filling station and to a final forming. In this process the packaging laminate is reformed into filled and sealed packaging containers having a parallelepipedic form. Various attempts have been made to increase steadiness and stability of the formed packaging containers. For instance US 6,446,858 suggests providing the packaging material with longitudinal crease lines in order to increase rigidity and appearance of the package. For the same purpose it has been suggested to double- fold the packaging material along one edge of the container. It may also be possible to modify the packaging laminate by incorporating different layers of different material. However, the in- creases in rigidity have been rather limited and in several cases not justifying the increased cost for the packaging laminate.

Summary of the Invention One object of the present invention is to increase the strength of the formed packaging containers and thereby be able to reduce the amount of material used. This is achieved in that the packaging containers formed are strengthened by means of embossments. Thanks to the emboss- ments the material of which the packaging containers are formed may be thinner and still have the same strength as packaging containers of a thicker material but not having any embossments.

In one aspect of the present invention the emboss- ments include defined longitudinal corners or edges of the packaging containers . The reinforced vertical package edges are created after that the packing material web has passed the last guide roller breaking the material web in a longitudinal direction. In a further aspect of the present in- vention the material web has no longitudinal crease lines, only crease lines for folding of the top and bottom of the formed package .

In a packing machine of the present kind the material web will pass a sterilizing bath and an aseptic chamber just before filling. In the sterilizing bath and the asep- tic chamber the material web is heated, normally to a temperature of 60-70 ⁰ C, in some cases the temperature may be as high as 100 ⁰ C. According to the present invention the embossing station is placed in or just below the aseptic chamber, which means that the material is hot when reaching the embossing station. Directly after the embossing station the packaging tube is filled, which will cool the material web. Thus, only a minor modification of existing equipment is required when practising the present invention. The heating and the subsequent cooling will establish and keep the embossing.

According to the invention the increased strength is achieved in that embossments are formed on the packing material web, after this has been formed into a tube, and that the material of the embossments is stretched in the cross direction. The stretching should not exceed 1-1.5% in order not to harm the material web. In order not to impair the achieved strength of the embossments it is extremely important that the material web should not pass any rollers bending the material web after the embossing and stretching.

According to one theory it is the lignin polymer of the carrier or core layer of the material web that gives the effect that the embossments are made more or less per- manent in the material when it is heated up and stretched. The pulp of which the carrier of the material web is formed contains a certain percentage of lignin. By increasing the lignin content of the normally unbleached pulp or core layer it should be possible to improve the positive effect of the present invention.

The form of some of the embossments is such that the packaging container becomes pleasing to grab and hold. Furthermore, the embossments of the packaging container should be aesthetically appealing. A person skilled in the art re- alises that the number of embossments as well as their placement and form may vary. Such variation may be due to desired strength, aesthetic considerations etc.

Further objects and advantages of the present invention will be obvious to a person skilled in the art when reading the detailed description below of at present preferred embodiments .

Brief Description of the Drawings

The invention will be described further below by way of examples and with reference to the enclosed drawings. In the drawings :

Fig. 1 is a sketch of a general packing machine, Fig. 2 is a schematic view of a filling and forming section of a packing machine, equipped with embossing tools according to the present invention,

Fig. 3 is a cross section view of a filling station of a packing machine,

Figs. 4 to 6 are plan views of different parts of the filling station of Fig. 3, Fig. 7 is a side view of a unit for forming defined corners according to the present invention,

Fig. 8 is a plan view of the unit of Fig. 7, Fig. 9 is one example of a profile formed by means of the unit of Figs. 7 and 8, Fig. 10 is a plan view, partly in section, of an embossing unit according to the present invention,

Fig. 11 is a driving unit for the embossing unit of Fig. 10,

Fig. 12 is one example of a profile achieved with the embossing unit of Figs. 10 and 11,

Fig. 13 is a plan view of an alternative embossing unit according to the present invention,

Fig. 14 is a plan view of the embossing unit of Fig. 13 in a second position, Fig. 15 is one example of a profile formed by means of the embossing unit of Figs. 13 and 14,

Fig. 16 is a plan view of a further embossing unit according to the present invention, Fig. 17 is one example of a profile formed by means of the embossing unit of Fig. 16,

Fig. 18 is a plan view of a still a further embossing unit according to the present invention,

Figs. 19a and 19b are sketches of a drive unit for the embossing unit of Fig. 18, and

Fig. 20 is one example of a profile formed by means of the embossing unit of Fig. 18.

Fig. 21 is a perspective view of the equipment in Fig. 2, Fig. 22 is a cross section view of the outer and inner embossing tools taken along the line A-A in Fig. 21,

Fig. 23 is a sketch of alternative embossing tools according to the present invention,

Fig. 24 is a sectional view taken along the line B-B in Fig. 22,

Fig. 25 is a perspective view of one example of a packaging container formed according to the present invention, and

Fig. 26 is a cross section view of the packaging con- tainer of Fig. 25.

Detailed Description of Preferred Embodiments The packing machine 1 of Fig. 1 is only shown as one example of a conventional packing machine. A packaging ma- terial web 2 is placed in the machine in the form of a roll 3. The packaging material web 2 may be a conventional packaging laminate, which includes a central carrier of paper, layer of aluminium foil and outside layers of liquid-tight and heat-sealable plastic material, usually polyethylene. The material web 2 is feed from the roll 3 by means of a number of guide rollers 4 and two register-holding devices 5. The register-holding devices 5 are used to control that the processing of the material web 2 takes place in register with crease lines on the material web 2. Finally the material web 2 is led vertically downwards. At the same time the material web 2 is formed into a material tube 7, by means of a tube-forming device 6. While moving continuously downwards the material tube 7 is filled with the desired content. The filled material tube 7 is then converted in to filled and closed packaging containers.

The material tube 7 is normally formed in an aseptic chamber 8. To fill the material tube 7 with the desired content a filling pipe 9 is arranged inside the material tube 7. The filling pipe 9 opens inside the material tube 7 below the aseptic chamber 8.

In that the embossing tools are placed in or just under the aseptic chamber 8 the material web is still hot, as it normally is heated to a temperature of about 60-70 ⁰ C by the sterilizing bath and in the aseptic chamber 8. Thus, the embossing is made on a hot material web. If needed additional heat can be given in the aseptic chamber 8 by means of hot air. In Fig. 2 and 21 a possible device 73 delivering the additional hot air is indicated. After the embossing unit the product is filled in the tube, whereby the material web is cooled to about 20 °C. The product level inside the filling pipe 9 is indicated at 76. It is believed that the stiffness increase achieved is due to a combination of the geometry of the embossed patterns, a small material stretch and the thermoplastic lignin prop- erties of the board. By exposing the material web for pressure at a temperature at about 60-70 °C and thereafter cooling it to about 20 ⁰ C the lignin substances in the cellulose fibres are probably affected in a way to preserve the embossments . Thus , the material web 2 does not pass any guide rollers redirecting the material web 2 after that the embossments have been made.

In forming of the filled, circular material tube 7 into packaging containers of rectangular parallelepiped form, as shown in the example of Fig. 2, the material tube 7 passes a number of square, tube forming rollers 77 after the tube has been embossed. The main purpose of these square, tube forming rollers 77 is to hinder that . the pressure of the fluid and possible pressure surges ruin the created rectangular form.

Generally, in forming the filled material tube 7 into packaging containers of rectangular parallelepiped form the material tube 7 passes a number of different stations. In the example shown in Fig. 3 there is a forming station 10 at the top, followed by a reshaping station 11 and a support station 12. Due to the embossment means and different stations for forming the material tube 7 into packaging containers, the packaging material web 2 may have only crease lines for forming the top and bottom of respective packaging container. Thus, in that case the material web 2 has no preformed continuous longitudinal crease lines.

In the forming station 10, arranged just below the aseptic chamber 8, a number of rollers 13 are placed forming a ring, mainly to assure that the tubular form is kept in the aseptic chamber 8. In the reshaping station 11 four rollers 14 are placed in a rectangular form in a common horizontal plan. In the reshaping station the material web is changing from a round form to a generally rectangular form. In the support station four rollers 15 are placed in a rectangular form in a common horizontal plan. The distances between the rollers 15 of the support station 13 correspond to the desired dimensions of the finished packaging container. The main purpose of the support station 13 is to hinder that the pressure of the fluid and possible pressure surges ruin the created rectangular form. As indicated above in some embodiments the embossing means are placed inside the aseptic chamber 8.

In the embossing unit of Figs. 7 and 8 four moveable embossing rollers 16 are arranged at the corners at the sides of the packaging container to be formed. The embossment means are placed above the product level 76 inside the material tube 7. The embossing rollers act on a parallel- epipedic cross section form in this case. The embossing rollers 16 on one side of the packaging container to be formed are each placed on top of a support 17. The supports 17 are placed on an axle 18. The embossing rollers 16 on the other side are each placed at an upper end of an angled link lever 19. The lower end of the angled link lever 19 is attached to a pivot 20. A further link lever 21 is placed with one end at a pivot 22 at the knee of the angled link lever 19 and the other end at a pivot 23 at a lower end of the support 17. The linkage is such that when the axle 18 is turned, it will move the embossing rollers 16 away and towards, respectively, the packaging material web 2, by means of the angled link levers 19 and the further link levers 21. Fixed support rollers 24 are placed at the short ends of the packaging container to be formed. The support rollers 24 are concave, having an edge area 25 with full diameter at each end of each support roller 24. The edge areas 25 have relatively short extensions.

In the embossing unit of Figs. 7 and 8 there are no inner embossing parts, such as embossing rollers or an embossing block. An embossment 26 is formed at each corner by cooperation between the embossing rollers 16 and the sup- port rollers 24. The embossing rollers 16 are placed a short distance from respective corner. The distance between each corner and the respective embossing roller 16 controls the form and radius of the embossments 26. Normally the embossing rollers 16 and the support rollers 24 are idle, thus, no driving units are needed. The movement of the ma- terial tube is used. However, in some cases it is possible to use a non-synchronous drive.

In Fig. 9 one example of a profile given by the embossing unit of Figs. 7 and 8 is shown. The formed emboss- ment 26 gives a well-defined corner having a small radius. The radius R should be less than 2 mm, preferably the radius R is about 1 mm. The well-defined corners having a small radius increase the stability of a filled and sealed packaging container, compared to packaging containers hav- ing no well-defined corners or corners with larger radius.

The embossment means may have many different forms giving embossings of different form on the finished packaging containers in addition to the defined corners.

According to the present invention embossing means may be arranged between the reshaping station 11 and the support station 12. In a first embodiment the embossing means have the form of four outer embossing rollers 27 and four inner embossing rollers 28. In the embodiment of Fig. 10 an inner embossing roller 28 is acting against an outer embossing roller 27 at each corner of the formed rectangular. A linkage system is arranged to be able to lift the outer embossing rollers 27 from the material web when the parts to form the top and bottom of the packaging container are passing. The linkage system has two link levers 29, 30 connected with one end each to a driving disc 31. The other ends of the link levers 29, 30 are connected to the middle of one arm 32 each. Each arm 32 is arranged pivoting at one end and at the other of each arm 32 a joint 33 is placed. A first link lever 34 is placed between the joint 33 of the arm 32 and a joint 36 of one outer embossing roller 27 and a second link lever 35 is placed between the joint 33 of the arm 32 and a joint 37 of another outer embossing roller 27. The two outer embossing rollers 27 are also connected to each other via a joint 38. The arrangement of the link- age system is such that by rotating the driving disc 31, the outer embossing rollers 27 will be moved towards or away from the material web by means of the arms 32, the first and second link levers 34, 35 and the joints 33, 36- 38. Thus, by movement of the driving disc 31, the outer embossing rollers 27 are moved out of or into contact with the material web. The driving disc 31 only needs a small movement to move the outer embossing rollers 27 out of contact at the areas of the top and bottom of the packaging container to be formed.

The outer embossing rollers 27 are driven by a driving motor 39 placed just below the embossing rollers 27, 28. In the shown example the outer embossing rollers 27 are driven by means of toothed belts 40, arranged between the outer embossing rollers 27 and drive rollers 41 connected to the driving motor 39.

The inner embossing rollers 28 are not driven and function as a kind of dolly.

In the example of Figs. 10 and 11 the embossments 42 are placed at the corners of the formed packaging containers, giving the corners a defined rounded form. The profile of such a formed packaging container is indicated in Fig. 12.

In the embodiment of Figs. 13 and 14 two pivotal sup- ports 43 carry one outer embossing roller 44 each. The supports 43 have a generally elongated form with the outer embossing rollers 44 placed at one end of respective support 43. Each support 43 has a pivot 45 at an end opposite the end carrying the outer embossing roller 44. The supports 43 are pivoted by means of a driving disc 46. The driving disc 46 has two pivots 47, each receiving one end of a link lever 48. The other end of the link lever 48 is connected to a further pivot 49 about at the centre of each support 43. The link levers 48 are arranged on the driving disc 46 in such a way that in operating position the pivots 47 on the driving disc 42 are on an imaginary line parallel with the supports 43. In the operating position the outer embossing rollers 44 will act against inner embossing rollers 50 to form the embossments. By rotating the driving disc 46 a short distance the embossing rollers 44 will leave contact with the material web 2, e.g. at the areas forming top and bottom of the packaging containers . When needed for setting of the packing machine, e.g. for installation of the material web the outer embossing rollers 44 can be lifted clear from the inner embossing rollers 50, as indicated in Fig. 14. The outer embossing rollers 44 are driven by means of a drive roller 51 at the end of the support 43 opposite the embossing roller 44. The drive rollers 51 are normally driven by a driving motor (not shown) by means of toothed belts, which drive rollers 51 are placed on axles inside the support.

In Fig. 15 a profile is shown having embossments 52 given by the embossing unit of Figs. 13 and 14.

In the example of Fig. 16 two supports 53 are ar- ranged having a pivot 54 towards one end. Each support 53 carries an embossing roller 55 at one end and a drive roller 56 at the other end. The pivot 54 is placed towards the end having a drive roller 56. In the same way as indicated above the drive rollers 56 are normally driven by means of toothed belts. The embossing rollers 55 act against an embossing block 57. The embossing rollers 55 have a number of ridges 58 acting against grooves 59 on the embossing block 57. The circumference of each embossing roller is adapted to the length of the packaging container to be formed. The ridges 58 of the embossing rollers 55 extend over a major part of the circumference of the embossing rollers 55. The relationship between the extension of the ridges 58 and the packaging containers to be formed is such that the parts of the embossing rollers 55 having no ridges will be in contact with the material web 2 in the areas forming top and bottom of the packaging containers . Thus, in this case the supports 53 do not have to be moved intermittently from the material web. However, the embossing rollers 55 may be turned away during setting of the packaging machine, in that the supports are turned around the pivots 54. The embossing rollers 55 also have a ridge at each end extended over the entire circumference of each embossing roller 55.

In Fig. 17 a profile given by the embossing unit of Fig. 16 is shown. The profile has an embossing 60 at each end given by the ends of the embossing rollers 55, and an embossing 61 with a wave form on each side, which wave form is given by the ridges 58 extended over parts of the circumferences of the embossing rollers 55. The embossing unit of Fig. 18 has four outer embossing rollers . Two embossing rollers 62 act on the short ends of the packaging containers to be formed and the other two embossing rollers 63 act on the sides of the packaging containers to be formed. The embossing rollers 62 placed at the short ends have a ridge at each end, extended the entire circumference, and acting against grooves in an inner embossing block 64. The embossing rollers 63 acting on the sides correspond with the embossing rollers 55 shown in Fig. 15. Thus, the embossing rollers 63 acting on the sides have a number of ridges 65 extending over parts of the circumference of each embossing roller 63 and ridges at the ends extending over the entire circumference of each embossing roller 63. The inner embossing block 64 has grooves for cooperation with the ridges of the embossing rollers 63.

The outer embossing rollers 62, 63 are driven by a common driving motor 66. The driving motor 66 acts on drive rollers 67, 68 at the outer embossing rollers 62, 63 by means of toothed belts 69, 70. To avoid crossing axles the toothed belts 69, 70 are placed on two different levels, which two levels are indicated in Figs. 19a and 19b, respectively. On one level the toothed belts 69 associated with the drive rollers 67 of the embossing rollers 62 at the short ends are placed. Thus, on the other level the toothed belts 70 associated with the drive rollers 68 of the embossment rollers 63 at the sides are placed.

In Fig. 20 a profile formed by the embossing unit of Figs. 18, 19a and 19b is shown. The profile has an embossment 71 at each corner and opposing embossments 72, having a wave form, at one end of the sides of a formed packaging container.

In the example of Figs. 21 and 22 outer embossing rollers 74 are placed just below the aseptic chamber 8 and can be released from the tube when necessary. The embossing rollers 74 act against an inner support 75 on the inside of the material tube 7, giving a radial counter pressure on the material tube 7. Below the aseptic chamber 8 the material tube 7 is reformed from a circular form to a paral- lelepipedic form. Support rollers 77 for the parallelepi- pedic form are placed between the embossing rollers 74 and a semi package jaw mechanism 78. Finally the material tube 7 is transversally sealed, formed and cut to separate packaging containers 83.

The units, such as volume flaps 85 and forming sta- tions 86 placed below the embossing tools should be adapted to the form of the embossments, in order to support the material tube 7 and the formed packaging containers and not impair the embossments. A certain increase of stiffness is also achieved by means of a positive pressure of about 0.5 bars when forming and sealing the containers in the volume flap 85 and forming stations 86.

In the embodiment of Figs. 23 and 24, the embossing unit is placed just under the aseptic chamber 8. In this case the embossing is made directly on the circular, formed material tube 7. In the shown example five outer embossing tools 79, in the form of rollers are placed in a circular form surrounding the material tube 7. Five inner embossing tools 80, in the form of low friction plates, are placed on the inside of the material tube 7 for cooperation with the outer embossing tools 79. The inner and outer embossing tools 79, 80 are placed at the ends of plate springs 81 and 82, respectively. The embossing tools 79, 80 may be moved to and from the material tube 7 by displacement means, normally acting on these plate springs 81, 82. By means of the plate springs 81, 82 the embossing tools 79, 80 will give radial forces to the material tube.

In Figs. 25 and 26 one example of an embossed packaging container 83, provided with embossments 84 according to the present invention is shown. In this example the emboss- ments 84 are given a sinusoidal form in cross section. As indicated above the geometry of embossments may be given other cross section forms, in order to get an optimal stiffness, especially regarding the four important vertical edges of the container. In view of the above described different embodiments a person skilled in the art realises that the embossment rollers and means controlling the position and driving of the embossing rollers may be varied in many different ways.