Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
The present invention relates to a method according to
the preamble of Claim 1, which is known, for example,
from US-A-5 443 546. This document illustrates a
solution in which a product such as, for example, a
praline or like food article, is wrapped in a close-
fitting wrapper maàe from two sheets, usually of
aluminium foil. The first sheet is formed into a bowl
shape so as to surround the major part of the product.
The other sheet is laid over the remaining part of the
product so as to take on a form complementary to that of
the product itself. After the two sheets have bee~
joined around their peripheries to give the desired
degree of sealing, the wrapper thus formed is shaped so
as to cause the first sheet to cover practically the
entire product, concealing the second sheet from view.
During the practical application of this method, the
Applicant has been able to note the particular importance
assumed by factors such as:
- the fact that, as a result of the shaping of the two
sheets closely against the product, their peripheral
regions which are ~oined become wrinkled which makes the
sealing conditions generally more critical;
- the fact that applications exist which differ from
that illustrated specifically in US-A- 5 443 546 in which
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one of the two sheets is not wrapped completely around
the product, coverins the other sheet: this is true,
particularly, in those applications in which sheets with
substantially identical ~im~n~ions are used instead of
one sheet being substantially larger than the other;
- the t~n~n~y, found to an ever increasing extent in
the packaging industry, to reduce the thicknesses of the
sheets constituting the wrapper without thereby reducing
the mechanical strength of the wrapper as a whole,
particularly with regard to risk of tearing, and
- the ever more stringent re~uirement to ensure the
hermetic sealing of the wrapper against external agents
such as moisture and other factors.
The object of the present invention is, therefore, to
provide an improved method, particularly with regard to
satisfying the requirements set out above.
According to the present invention, this object is
achieved by a method having the further characteristics
claimed in Claim 1. A further subject of the invention
~ is the related equipment as called for
~ in Claim 10.
In summary, the invention is based on the recognition of
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the fact that, in an unexpected manner, the requirements
explained above are satisfied excellently if the two
sheets which are connected together in order to close the
wrapper are joined over a surface which is generally
conical or, more correctly, frusto-conical in shape (the
term "conic" and "frusto-conic~ also includes substantially
similar or equivalent geometries such as, for example,
pyramidal or frusto-pyramidal) instead of in a plane
which is generally perpendicular to the direction in
which the sheets are brought together (or coupled).
The invention will now be described purely by way of non-
limitative example, with reference to the appended
drawings in which:
- Figures 1 to 6 illustrate successive steps in the
method according to the invention, and
- Figure 7 illustrates the final result of the
wrapping operation comprising the steps illustrated in
Figures 1 to 6.
The product which it is intended to wrap is constituted,
in the embodiment illustrated, by a praline P having a
shape which can be likened approximately to a sphere.
More specifically, in the embodiment illustrated here,
(which is such), reference is made to a praline of a type
known per se constituted by an upper hemispherical part
which overlies a lower cylindrical or upwardly-diverging
frusto-conical part. The praline P in question may be
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likened approximately to a spherical praline P having a
sort of squashed lower part bounded by a flat base.
More particularly, as will be better explained below, and
as will best be appreciated from a comparison with the
drawings of US-A-5 443 546 the praline P illustrated in
the appended drawings lends itself to packaging in a
closely fittlng wrap~er of sheet material without
requiring insertion in a paper cup in order to isolate
and stabilise it.
With regard to the nature of the product P, one may, for
example, be dealing with a praline constituted by a wafer
shell with a paste or cream filling and an outer coating
of chocolate, for example with nuts, or like coatings
with the possible addition of shredded coconut, hazelnut
chips, etc such as to give the outer surface of the
praline P a generally irregular appearance.
This factor may make the wrinkling of the sheets
constituting the wrapper around the zone of sealing more
evident during the formation of the wrapper: it is this
latter appearance which has already been indicated in the
introduction to the present specification.
It should, however, be stressed that the invention can be
applied to products of an entirely different nature and
shape. While remaining within the field of the
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confectionary industry, reference may be made to hollow
or filled chocolate eggs, various chocolates, pralines of
generally spherical shape with a flat base, small
meringues, etc.
In order to form a closely fitting wrapper around the
product P, two sheets of aluminium foil or other sheet
material indicated 1 and 2 are used.
The choice of a sheet of aluminium is considered
preferable because of its ready adaptability to the shape
of the product even if this has surface irregularities.
In particular, it is preferred for the two sheets 1 and
2 to be of the type generally defined as "coupled",i.e.
coated on their inner faces intended to face the product
P with a layer of hot-melt material and/or resin which
can enable them to be joined together by a sealing
process (typically heat-sealing or ultrasonic welding).
Depending on the applicational requirements, however,
alternative solutions are possible, varying from simple
connection by mechanical shaping to welding (glueing)
with the supply of additional material which may make the
use of a "coupled" material superfluous.
The best results have been obtained up till now by the
Applicant with the use of alumlnium foils, possibly
embossed, and having thicknesses of between 7 and 12
microns, coated on their inner faces with a coupling film
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of a material such as polythene, polypropylene, polyester
and the coupling film known commercially as SURLYN. The
thicknesses of the films used were in the range 3/4
microns for the SURLYN (equivalent to a weight of the
order of 9-lOg/m2) to 5-12 microns for the polyolefin
films mentioned above.
Experiments carried out by the Applicant have given
excellent results even for the thinnest films (aluminium
plus coating). This is in terms of tearing risk and with
regard to sealing and resistance to penetration by
external agents.
In the embodiment of the invention illustrated here, the
two wrapper sheets 1 and 2 have substantially the same
dimensions. Naturally, it would be possible to make
different choices, such as that described, for example,
in US-A-5 443 546 in which one of the sheets has much
greater dimensions than the development in plan of that
part of the product which it faces and than the other
sheet.
In order to clarify this, in the embodiment illustrated
here, one may consider the sheets 1 and 2, which are
usually square or rectangular, to have such dimensions
that each can cover slightly more than half the product
P, thus leaving the opposite part of the product
uncovered.
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The two halves of the product indicated above (upper
hemispherical cap and cylindrical or frusto-conical base)
may be seen as separated by an imaginary equatorial plane E
which identifies the maximum section of the product: it
will, however, be appreciated that this is true even if
the product P has a different shape, such as, for example
a spherical or ovoid shape, or a shape which reproduces
the features of a person in miniature. Whatever the
shape of the product P, it will, in general, always have
an identifiable equatorial plane which defines its zone
of maximum section: in this respect, one may again note
that sweet products, whatever their nature, are very
often constituted by two complementary parts (hollow or
filled) joined together at such an e~uatorial plane.
This equatorial plane is, in turn, perpendicular to the
general direction (indicated D in Figure 3 of the
appended drawings) in which the two halves of the product
P are brought together. As will be better understood
from the following, this is the same direction as that in
which, the two sheets 1 and 2 are brought together.
The first step in the operation of wrapping the product
P consists of forming the sheet 1 into a generally cup or
bowl shape.
This operation may be carried cut, for example, by means
of a tool comprising a die having a cavity which can be
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entered by a punch: for a schematic representation of
this solution, reference may be made to the document
US-A-5 443 546 already mentioned several times in the
presentation description.
In a particularly preferred embodiment of the'invention,
however, the shaping of the sheet 1 is achieved by means
of a generally tubular forming tool 100 in which a vacuum
(subatmospheric pressure) source, schematically indicated
D, acts. The source D acts, in known manner, to draw the
sheet 1 into the tubular cavity of the tool 100, forming
the latter into a corresponding cup-shape. The suction
causes the evacuation of any air bubbles which might form
during both the shaping and the subse~uent steps of
forming the wrapper from the sheets 1 and 2 and, in
particular, in the cavity jointly formed thereby.
Shaping under these low-pressure or vacuum conditions
(or, in general, by evacuation of air) has been found to
be particularly advantageous for achieving very close
fitting of the wrapper formed by the sheets 1 and 2
around the product P.
It will also be appreciated that the mouth portion of the
tool 100 in correspondence with which a corresponding
mouth part of the cup-shaped sheet 1 is formed, is
generally frusto-conical in shape, following a
theoretical conical surface, the axis of which coincides
with the central axis of the tool 100. This axis is in
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turn oriented in the general direction of coupling of
the sheets 1 and 2 (direction D in the drawings).
As has already been stated in the introduction, the use
of a frusto-pyramidal surface with a sufficiently large
number of sides would be equivalent.
The conic angle is preferably of the order of 45~, with
the option that this could be increased or reduced to
accord with specific applicational requirements,
particularly with regard to the material constituting the
sheets 1 and 2.
Again, in the embodiment illustrated in the drawings, the
conicity is oriented with an upward divergence whereby
the sheet 1 has an upwardly flared open mouth when the
shaping is completed.
This choice is made for reasons which will become clearer
below and, in particular, in the embodiment illustrated,
because the edge of the sheet 1 is intended to be folded
upwardly so as to cover at least part of the sheet 2 in
the finished wrapper.
The use of a complementary solution could however be
considered (as confirmed by specific experiments made by
the Applicant), the sheet 2 being folded downwardly over
the sheet 1 covering the product P. In this case, the
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complementary shaping required for the mouth portion of
the sheet 1 could be achieved by forming the edge portion
102 with an upwardly converging conic shape, that is
diverging downwardly, or - as will be understood - by
adopting, for the tool 100, a configuration similar to
that adopted for the tool 104 which will be described
below.
While the body of the tool 100 is made from a generally
rigid material, typically metal, the mouth portion 102 is
preferably made from a generally softer material
(typically an insert), for example TEFLON.
The generally concave, or cup-shape, given to the sheet
1 is intended to render this able to receive the product
P (in the example illustrated, the lower part) within it
as shown schematically in Figure 3. This drawing
presupposes that the product P is introduced (by known
means, not illustrated) into the sheet 1, shaped into a
cup-shape, while the latter is still within the die 100.
This choice, although preferred (particularly with regard
to the choice of the vacuum source D), should not be
considered essential. After the sheet 1 has formed
shaped into the cup-shape, it may be removed from the
tool and transferred to another cavity arranged to
support the sheet 1 for the insertion of the product P.
This is preceded or followed by insertion in a shaping
tool having a mouth portion similar to the mouth portion
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102 so as to give the mouth portion of the sheet 1 the
desired conical shape.
It goes without saying that the solution described herein
with reference to the drawings has been found to be
preferable in terms of optimising the procedure.
In these conditions (that is, in the position illustrated
in Figure 3) the other sheet 2 is now applied over the
product P.
This result may be achieved by the supply (by known means
not illustrated here) of the sheet 2 so as to adapt it to
the upper part of the product P which projects above and
out of the mouth portion of the cup-shaped sheet 1.
Preferably the sheet 2 is applied by means of a suction
tool 104 which ensures that the sheet 2 remains in the
desired position for the forming of the sheet 2 itself by
means of a tool 106 which may be constituted by the same
tool 104 as that which positions the sheet 2 over the
product P.
In the embodiment illustrated here, and with particular
reference to Figure 4, it is assumed that the tool 104,
which also has a generally tubular structure, is also
connected to the vacuum source D which acts on the lower
tool 100. It is thus presumed that the sheet 2 is held
so~tly against the downwardly facing mouth portion,
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indicated 106, of the tool 104 as a result of the low
pressure in the tool 104, the pressure in which is
suitably reduced relative to that in the tool 100.
Naturally this is only one of the various solutions
possible. For example, one may consider supplying the
sheet 2 horizontally over the product P and retaining it
in this position by means of a pusher element which fits
on to the polar region of the product P from above so as
to retain the sheet 2 when necessary.
Yet other solutions are possible: in each case, one is
dealing with constructional details which do not in
themselves have specific relevance for the purpose of
carrying out the invention.
From an observation of Figures g and 5 it will be seen in
particular, that the tool 104, usually of rigid material,
such as metal, has a mouth portion 106 which is shaped
externally with a frusto-conical surface (a reminder is
again given that this term also includes frusto-pyramidal
and like geometries) complementary to the frusto-conical
internal shaping of the mouth portion 102 of the tool
100. In other words the mouth portion 106 of the tool
104 is made so that it can enter the mouth portion 102 of
the tool 100 in such a manner that their respective
frusto-conical surfaces are brought into frontal mating
conditions.
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As best seen in Figure 5, the equipment as a whole is
such that it clamps together the peripheral portions of
the sheets 1 and 2 which are brought together with their
faces which may be coated with resin or lacquer, as
mentioned previously, in contact. These peripheral
portions of the sheets 1 and 2 are thus disposed on the
frusto-conical surface defined jointly by the mouth
portions 102 and 106 of the first tool 100 and the second
tool 104 respectively.
As stated above, the mouth portion 102 of the tool 100 is
preferably of a slightly deformable material (for example
TEFLON). In a complementary manner, the mouth portion
106 of the tool 104 (made of a hard material such as
metal) has sculpturing, for example annular grooves 107
(shown in Figure 4 even though they are not clearly
visible for obvious reasons of scale). When the tools
100 and 104 are pressed axially against each other, the
compressive force is such as to make the sculpturing 107
of the mouth portion 106 of the tool 104 deform the mouth
portion 102 of the tool 100 into a complementary shape,
for example with circular grooves. Naturally, the
peripheral portions of the sheets 1 and 2 which are
clamped between the mouth portions 102 and 106 of the
tools 100 and 104 also take on corresponding proriles,.-
that is a profile which, as seen in vertical section as
in Figure 5, may be defined generally as corrugated.
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14
This shaping of the peripheral portions of the sheets 1
and 2 which are joined together is intended to improve
the seal between the two sheets, and hence the air-
tightness of the wrapper formed, overcoming problems due
to the fact that, as a result of their shaping around the
product P, the portions of the sheets 1 and 2 intended to be
joined together are themselves generally wrinkled.
As already stated, the facing marginal portions of the
two sheets 1 and 2 may be sealed together in various ways
to make the wrapper air-tight. It is possible to make
use of purely mechanical coupling by making the local
pleating resulting from the presence of the sculpturing
107 more firm, or to bond with additional material
(glueing) or to make use, as is currently preferred, of
heat-sealing, preferably by promoting the fusion (by the
application of direct heat or ultrasonic vibrations) of
a hot-melt coating provided on the inner faces of the
sheets 1 and 2.
This latter may be achieved simply by forming the tool
104 as a heat-fusing tool of the type currently used, for
example, to apply sheets of aluminium foil coated with
hot-melt material (so-called coupled aluminium) to the
mouths of cup-shaped containers containing liquids or
pastes, for example yoghurt and like products. For this
purpose, the tool 104 has associated heating means shown
schematically in Figures 4 and 5 in the form of resistors
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108; obviously one is dealing with a schematic
representationi the specific details are well known to
experts in the art and do not require to be illustrated
here, particularly since they are not relevant for the
purposes of an understanding of the invention.
The presence within the tool 100 (and, as has been seen,
in the tool 104 as well) of a subatmospheric pressure
(vacuum) has been found to be excellent for the purposes
of achieving a global action of evacuating the air from
the zone in which the wrapper is applied and closed
around the product P. This avoids the finished wrapper
retaining air between the outer surface of the product P
and the inner surfaces of the closed wrapper, which air
could cause deterioration of the product or undesirable
inflation of the final confection; this latter factor
could cause the wrapper to tear.
After the sheets 1 and 2 have been sealed in the manner
described, the product P finds itself wrapped in a sheet
wrapper having the characteristics illustrated more
clearly in Figure 6. In practice, the lower and upper
parts of the product respectively are tightly covered by
the sheets 1 and 2, the peripherai portions of which are
sealed together so as to form a so-called "ring of
Saturn", that is, a collar lO projecting around the
product P.
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Contrary to the effect shown, for example, in the
solution of US-A-5 443 546l the said collar or ring of
Saturn 10 is not planar but, on the contrary, is frusto-
conical, with a conic angle ~ defined by the conic angle
of the mouth portions 102 and 106 of the tools 100 and
104.
This particular shaping of the collar lo means that, when
it is further formed, so as to be folded against the
product P to give the final configuration illustrated in
Fiure 7, the zone along which the sheets 1 and 2 are
joined is not subjected to appreciable stress.
Experiments carried out by the Applicant have shown that
this factor is important to ensure the sealing of the
wrapper and to ~; n; mi se the risk of tearing during
subsequent operations.
The particular shaping of the collar 10 is thus such that
it is already pre-shaped in the direction of its final
desired deformation: the collar 10 has, so to speak,
already been given a so-called "inducement" towards its
final position.
As, moreover, has already been stated, in the embodiment
illustrated here, the sheet 1 in the final wrapper is
folded at the collar 10 so as to lie against the product
P and the collar part of the sheet 2. In other words,
with reference to Figure 6, the collar 10 is folded
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upwardly.
This choice is not however imperative. It would in fact
be possible to consider the exactly complementary
solution, for example a solution in which the collar 10
is folded downwardly so that:
- the upper part of the product P is covered by the
sheet 2,
- the lower peripheral portion of the product is
covered both by the sheet 1 and the sheet 2 folded
closely over the sheet 1 and
- the base portion of the product, facing downwardly
is covered solely by the sheet l.
In this case, naturally, the collar 10 would be given an
"inducement" in the opposite direction from that
illustrated in Figure 6, such that, instead of being bent
upwardly, the collar 10 would be bent downwardly (still
in a frusto-conical form).
This result may be achieved in at least two different
ways, that is:
- by forming (as already suggested above) the
surfaces of the mouth portions 102 and 106 of the tool
100 and 104 in a manner complementary to that
illustrated, the mouth portion 106 of the tool 104 thus
having a flared mouth which opens downwardly and in which
a tapered mouth part 102 of the tool 100 is inserted; or
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simply
- by leaving the geometry of the tools 100 and 104
the same as that illustrated in Figures 2 to 5 but
reversing the m~nner of introduction of the product P, by
inserting the product P in the tool 100 in a condition in
which it is overturned through 180~ with respect to that
illustrated in Figure 3, that is with its upper cap
portion facing downwardly and not upwardly.
The subsequent treatment of the collar 10 (whatever its
orientation) can also be achieved in various different
ways. The collar 10 may simply be formed against the
product P or, before being formed against the product P,
the collar may be cut as shown schematically in Figure 7.
The solution illustrated in Figure 7 is particularly
pleasing from an aesthetic point of view when the sheets
1 and 2 have different colours from each other, the sheet
1 for example being green and the sheet 2, gold or
silver. In this case the sheet 1 has the effect of-
simulating a type of leaf in which the product P is
enveloped. In each case it will be appreciated that a
solution such as that illustrated in Figure 7 allows the
pleated paper cup often used for the packaging of
products such as that illustrated to be dispensed with.
With regard to the folding of the collar portion 10
against the product, it is possible to use various
generally known techniques, such as the use of a tool
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19
similar to that described in US-A-4 510 735
or the product P may simply be allowed to fall
through the cavity in the tool 100 from the position
illustrated in Figure 5 after the tool 104 has been
raised in order to loosen the clamping action exerted on
the collar 10 by the tools 100, 104 during sealing.
