Package making – Progressively seamed cover web or web folds – With closing of web between package units
Reexamination Certificate
2001-09-04
2004-04-27
Smith, Scott A. (Department: 3721)
Package making
Progressively seamed cover web or web folds
With closing of web between package units
C053S563000, C053S565000
Reexamination Certificate
active
06725634
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a counter rail and to a combination module of a counter rail and a dolly respectively, suitable for use in an apparatus for heat sealing a laminated packaging material for packaging of a liquid or flowing product.
The invention also relates to an apparatus for heat sealing and to a sealing/cutting apparatus including said counter rail and dolly, as well as to a packaging machine including such a sealing apparatus and counter rail and dolly of the invention.
Furthermore, the invention relates to a method of producing said counter rail and dolly.
BACKGROUND OF THE INVENTION
Food packaging processes of today (with the term “food” is meant all sorts of solid and liquid food, such as juices, milk and other beverages as well as pastes, soups, jellies and cheese) often are of the type “form-fill-seal” and may be carried out by shaping a continuously moving web-shaped packaging material made of a flexible laminate into a continuously running tube, continuously filling the tube with the desired food product to be packaged and by sealing and finally cutting off sealed packages from the tube. An example of such forming of a tube from a continuous web of packaging material and the further formation of packaging containers is schematically shown in
FIG. 1
a.
The packaging processes are often high speed continuous processes, wherein the packaging material in the form of a web is continuously fed through a machine, sterilised, for example by passing through a liquid or gas-phase quick-acting sterilising medium, formed and sealed into the required tube-shape for being filled with the food to be packaged and finally transversally sealed.
The continuous web-shaped packaging material is manufactured with a packaging material manufacturing machine and placed on a reel. The packaging material often has a laminated structure comprising a core layer of paper or paperboard, an outer heat sealing layer of a thermoplastic polymer (such as for example polyethylene) on each side of the core layer and, if necessary, an aluminium foil gas-barrier layer interposed between the paper core layer and the film. Alternatively, a gas-barrier layer of a plastics or inorganic material, such as for example polyamide, polyethylene vinylalcohol (EVOH) or siliconoxide, may be employed instead of aluminium foil.
The reel with packaging material is installed in the packaging machine where it is reeled out and routed within the packaging machine using drive mechanisms disposed in several positions in the machine. The packaging material web is shaped into a tube and sealed in the longitudinal direction within the packaging machine. While the tube is being transferred downward within the packaging machine, the liquid or flowing food product is supplied from above to fill the inside of the tubular packaging material. Next, the packaging material tube is squeezed laterally from both sides and sealed in the lateral direction at specified intervals to form interconnected, filled and sealed packaging containers. Next, the sealed packaging containers are separated off from the tube by cutting between the laterally extending sealed portions, and the thus separated packaging containers are brought into a specified, desired shape, for example by folding and bending along previously formed crease lines in the packaging material, and, if required, finally sealed in order to remain in that shape.
The sealing of the tubular packaging material in the longitudinal or lateral direction is carried out by heat sealing of the outer surfaces of the packaging material, which are made of heat sealing thermoplastics, to each other. This may be performed by known heat sealing techniques, such as for example induction heat sealing, radio frequency (RF) or microwave heat sealing, heat convection sealing or ultra-sonic vibration heat sealing. A very common heat sealing technique today for the transversal heat seals in the case of aseptic packaging, is the induction heat sealing, wherein the aluminium foil in the packaging laminate co-acts with an inductor in order to generate heat. The thermoplastic surfaces are bonded to each other by heat fusion by simultaneous application of the induction current and pressure.
Alternatively, packaging processes may often be of the type that are forming packages from pre-cut blanks of packaging material. An example of a principle for such 6 packaging process is shown in
FIG. 1
b.
Pre-cut blanks of packaging material may be fed into a packaging machine, folded and longitudinally sealed, fold-formed and sealed at the bottom in order to provide open package capsules. The capsules are filled and subsequently sealed at the top, thus providing filled packages (
11
″).
Conventional packaging machines thus employ a heat sealing apparatus to seal the packaging material. The sealing apparatus is normally provided with so-called counter jaws and heat seal jaws disposed and working in opposing relation to each other.
An example of such a heat sealing apparatus is schematically shown in
FIG. 4
, while a cross-section view of a typical counter jaw and a heat-seal jaw is schematically shown in FIG.
5
.
Conventionally, for transversal heat sealing, each counter jaw is provided with a pair of counter rails, while each heat-seal jaw is provided with a sealing block. Each counter rail and oppositely facing seal block are capable of creating one transversal heat seal across the packaging material. A cutter may be disposed in the gap formed between the two counter rails. Each cutting rail is provided with a counter element, a so-called “dolly” or “pressure pad”, that extends along the counter rail, while the sealing block, in the case of induction sealing, is provided with an inductor coil disposed opposite to the dolly. Most commonly, in the case of packaging into a continuous tubular packaging material, the sealing and cutting operations are performed in the same part of the pack aging process, in which cases the counter rail is also called “cutting rail”. However, it is also fully possible to separate the sealing and the cutting operations from each other, for example by subsequently cutting the filled and sealed tube in a separate cutting unit.
FIGS. 2 and 3
, schematically illustrate a side-view of a conventional counter rail and sealing block for induction sealing, disposed on opposite sides of the packaging material to be heat sealed, before and after the sealing has been carried out.
As shown in
FIGS. 2 and 3
, the packaging material walls
12
,
13
of a tube or capsule may be placed in face to face relation to each other in a sealing zone S, for transversal induction sealing of the for example tubular packaging material
11
. Each of the packaging material walls
12
,
13
is normally of a laminate structure made up of a paper base layer
14
, and a film layer
16
of polyethylene, for example, located on the inside surface of the aluminium foil layer
15
. Although not specifically illustrated, the outside surface of the paper base layer
14
is also coated with a layer of plastics material such as polyethylene. The polyethylene portions
16
of the two packaging materials
12
,
13
are bonded together by heat fusion.
In other heat sealing methods, such as in high frequency (RF) sealing or heat convection sealing, an aluminium foil layer is not needed for the generation of heat.
The counter rail
21
normally is made of steel, and fulfils the requirements on planarity and parallelism. Depending on i.a. the requirements of the seal quality, the type of packaging material, the size of the package and the type of product to be packed, the shape and mechanical properties of the dolly
22
may be varied to suit the circumstances best. In the case of high quality seals as in the case of the present invention, such as for example for aseptic or long-term storage, so-called “extended shelf-life” packaging, the dolly needs to have some degree of flexibility and compressibility for control of the flow of the heated thermoplastics from the layer
16
in the seal zone S
Martell Martin
Mazzetto Maurizio
Palmqvist Roland
Shokri Ebi
Nathaniel Chukwurah
Smith Scott A.
Tetra Laval Holdings & Finance S.A.
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