Note: Descriptions are shown in the official language in which they were submitted.
37~
The invention rela-tes to a machine for applying a
fllm. I-t is used in particular for applying a film of poly-
propylene or acetate to a cardboard support comprising cut-
outs. The arrangement constituted by the cardboard support
coated with a film will in particular make it possible to
produce packing boxes comprising at least one transparent
window through which it is possible to see the product
located inside the box.
At present, there are a large number of machines for
applying film which make it possible to apply a film of
polypropylene or acetate to the front side of a cardboard
support which is generally printed previously in order to
give the arrangement a shiny appearance. In the case where
the film applied is polypropylene or another synthetic
material, the final product obtained moreover has the
advantage of being waterproof and moreover is much stronger.
This type of machine generally comprises a winding
arrangement on which is stored the roll of film whereof the
width is identical to that of the cardboard surface to be
coated. The machine comprises a glueing station which makes
it possible to coat one face of the film with a uniform layer
of glue then, the glued film is applied to the cardboard
support by the intermediary of two rollers between which the
film stuck to the front side of the cardboard support is
compressed. The band produced in this way is cut up and the
cut cardboard supports may be made into boxes depending on
the use for which they are intended.
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This type of machine does not involve great difficult-
ies as regards production and is satisfactory in its use.
On the other hand, in the case of cardboard supports
comprising cut-outs, machines of the preceding type cannot
be used directly. In Eact, in the vicinity of the cut-outs,
the glued film is no longer applied to a support and
consequently represen-ts an adhesive surface to which all the
impurities present in the manufacturing workshop may stick.
Thus, the resulting product does not fulfil its function
absolutely, since the window no longer has perfect trans-
parency and the final product loses its attractive appearance.
Consequently, at the present time, the production of
transparent windows in packing boxes is obtained by coating
the periphery of the cut-out in the cardboard support with a
glue which is compatible with the materials to be assembled,
this coating being applied to the rear side of the cardboard
support. Then, a film cut to the dimensions suitable for the
window which it is intended to cover is applied to the glued
rear side of the cardboard support.
In this case, it is the support which is coated with
glue and the film is simply applied to the rear side of the card-
board support. It is not possible to apply glue to the film
as has been explained previously, in view of the fact that
the glued part of the film which is not applied to the support,
is in contact with the open air and rapidly becomes opaque.
~oreover, it would be extremely difficult to glue solely the
periphery of the film, which is contact with the cardboard
-- 4
support.
It would also be very unattractive to g].ue the film
to the front side of the cardboard sheet, since in this case
the bead of glue would be visible and this would then cause
a superficial deEormation of the resulting product.
In conclusion, present packaging comprising windows
is expensive, since it is ill-suited to automatic manufacture
and moreover requires large quantities of glue in view of
the fact that the cardboard support coated with glue absorbs
a large part of the liquid glue.
Furthermore, if one wishes to obtain packaging
benefitting from the properties provided by the outer coating
of film, it is necessary to carry out a double operation,
namely the application of the outer film, then, cutting out
of the window and finally the provision of an inner window
of film.
This type of packaging is thus not widely used at
present, despite its very attractive economic role from
the client's point of view.
The main object of the present invention is to
provide a machine for applying film, which is capable of
applying a film of polypropylene or acetate -to a cardboard
support comprising cut-outs. The film is applied to the
front side of the cardboard support, which will make the
support waterproof and stronger. Thus, the application is
direct and it is no ~onger necessary to proceed with
processing of the cardboard supports on another machine in
order to provide a transparent window in the cardboard
support comprising cut-outs.
5~ 37~
Moreover, the machine for applying film will leave
no trace on the cardboard suppor-t coated with film, in order
that the final product obtained is homogeneous and has a
pleasant appearance.
The machine for glueing will be particularly
suitable for carrying out a particular glueing method in which
the glue has very rapid drying properties after it is applied
to the cardboard support, so that the various impurities
present in the manufacturing workshop are not able to stick
to the film in the region of the transparent window and thus
make the latter opaque.
The rnachine for applying the film will have a
geometry of construction such that the glued surface of the
film in the vicinity of the window, never comes into contact
with any part of the machine or outer member before it is dry.
In fact, it has been noted that the least contact of the
surface of the glued film when the glue is not completely
dry, with any surface such as the periphery of a return
roller or the like leaves an imprint on the film which
impairs its transparency.
Thus, at the present time, when one attempts to
apply a film to a cardboard support comprising cut-outs with
traditional machines for applying films, one cannot fail
to obtain a final product which comprises traces in the
vicinity of the transparent window which are produced by
the passage of the film between the pressure and counter-
pressure rollers which apply the film to the cardboard
support.
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Now -the machine according to the presen-t invention
ma]ces it possible to obviate these drawbacks in order to
obtain a finished product of high quality.
The machine for applying film intended in part-
icular for applying a film of polypropylene or acetate to acardboard support comprising cut-outs, comprises a winding
arrangement in which the roll of film is stored, a station
for glueing the surface or the film, a tunnel oven in which
the glued film is heated, an applicator group composed of a
pressure cylinder and a counter-pressure cylinder pressed
tangentially one against the other between which passes the
glued film superimposed on the front side of the cardboard
support, is characterised by the fact that rneans deflect the
arrangement of the eardboard support eoated with film,
leaving the applieator group, in order to separate it from
the eounter-pressure roller.
The invention will be better understood on
referring to the following deseription and to the aeeompanying
drawings whieh form an integral part thereof.
Figure 1 is a general view of the maehine for applying a
film, eonstrueted aeeording to a preferred embodi-
ment.
Figure 2 shows the operation of the glueing station, in
detail.
Figure 3 shows the operation of the applicator group provided
with deflection means according to the invention, in
detail.
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'3'7~
The machine for applying film of the invention is
illustrated in Figure 1 in a preferred embocliment.
The latter is a machine having a longi-tudinal
arrangement necessary for successively carrying out the
various operations necessary for processing the film.
In fact, according to the present invention, the
machine for applying film has the feature of applying film
to the front side of cardboard supports whilst being ~dapted
to the fact that the latter comprise cut-outs.
The advantages of applying film to the outer face
of the cardboard support are thus retained, namely greater
solidity, a shiny appearance and possibly water proofing of
the product, when one uses a polypropylene film for example.
However, the machine is equipped in order to apply a film of
any nature, in particular an acetate or polypropylene film.
Now, in view of the desired final characteristics, it is
obvious that the film will advantageously be transparent.
In order to reduce the length of the machine, the
latter will have an arrangement for treating the film on two
levels.
According to the embodiment of the machine for
applying film illustrated in Figure 1, the latter integrates
the various working stations necessary for the application of
the film to the cardboard support. At one end the frame 1 of
the machine comprises a winding arrangement 2 in which the
roll of film 3 is stored. In general, the width of the film
will be identical to the width of the cardboard support to be
covered with film. It is possible to place several rolls side
-- 8 --
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by side in orcler to apply a film to cardboard supports
arrangecl in parallel.
The film coming from the winding arrangement 2 is
introduced into a glueing station 4. In fact, it has been
chosen to glue the film rather than the cardboard support in
order to save on the consumption of glue, in fact, due to
their porous composition, cardboard supports absorb a large
part of the glue applied to their surfaces and consequently,
it is necessary to use large quantities thereof in order to
obtaln satisfactory results.
Consequently, the glueing station 4 makes it
possible to coat the surface of the film with a film of glue
of constant thickness over its entire surface.
Figure 2 shows a preferred embodiment of the glueing
station 4. The latter firstly comprises a longitudinal vat
5 filled with glue 6. This glue 6 has properties of adhesion
which make it suitable for the surfaces to be stuck.
The vat of glue 5 will advantageously be of small
capacity in order that the glue 6 contained in this vat does
not dry. The vat 5 will advantageously work with a constant
level, that is to say that a device for supplying glue will
fill the vat 5 as it is needed, in order to keep the volume
of glue present in the vat 5 constant.
A glueing roller 7 arranged transversely in the vat
5, with respect to the direction of travel of the band 8 of
film, is immersed by its lower part in the bath of glue 6
present in the vat 5.
- 9 - ~3L31 ~a3~7i7~
A rol.ler 9 around whi.ch the bancl o:E film 8 winds is
arranged tangential.ly with respec-t to the glueing roll.er 9
so that the surface of the band 8 which is in contact with
the glueing roller 7 is coated with glue.
In order to deposit a film of glue of substantially
constant thickness over the entire surface of the band of
film 8, the glueing station 4 will be provided with an
equalizing roller 10. This equalizing roller will be arranged
tangentially with respect to the glueing roller 7 and it is
possible to adjust the spacing between the two rollers 7 and
10 in order to obtain a thickness of the film of glue present
on the periphery of the glueing roller 7 which is adapted to
requirements. This film of glue deposited on the periphery
o:E the glueing roller 7 will then be deposited by capillarity
on the band of film 8, at the time of its tangential contact
with the glueing roller 7.
The glue used will advantageously be of a type containing
heat-sealing products and a hardener, further more it will
have good transparency when dry.
The glued band of film 8 leaving the glueing station 4
will then be introduced into a tunnel over 11 loca-ted in the
upper stage of the machine 1. This tunnel oven is of the
conventional type and in its lower part comprises a series of
driven rollers on which the glued band of film rests, which
.25 is thus carried along. The upper part of the tunnel over 11
is composed of an electrical heating resistance which thus '`
raises the temperature of the film and above all of the coating
- 10 ~
of glue present on the upper surface.
On leaving the tunnel oven 11, the glued band of
film 12 passes :in-to the applicator unit 13. Located upstream
of this applicator unit 13 is the store of cardboard supports
14, which makes it possible to forward them one after the
other, thus depositing them in succession on a conveyor
belt 15.
Thus, the applicator group 13 is supplied on the one
hand with glued film 12 and a cardboard support which,
according to the present invention, comprises internal cut-outs.
A conventional suction device 16 will be located in
the lower part of the conveyor belt 15 in order to press the
cardboard supports against the conveyor belt thus to prevent
any relative sliding of one cardboard support with respect to
the other. In fact it is preferable to arrange the cardboard
supports edge to edge, since the band of film is applied
continuously and thus there is no wastage of film.
The applicator group 13 is illustrated in detail in
figure 3. It is composed in particular of a pressure roller
17 arranged transversely with respect to the direction of
travel of the cardboard supports 14, for acting on the band
of film 12. A counter-pressure roller 18 is arranged tangen-
tially with respect to the pressure roller 17. The glued
band of film 12 as well as the cardboard supports 14 are
introduced between the pressure roller 17 and counter-
pressure roller 18 in order to apply the glued film 12 to
the front side of the cardboard supports 14.
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A hydraulic jack will press the counter-pressure
roller 18 -tighly agains-t the pressure roller 17 in order to
press the film onto the cardboard support. On the other
hand, when the machine is no-t in use, the jack will be
actuated in order to separate the rollers 17 and 18.
The roller 17 will be a rigid roller which will
advantageously be chromium-plated on its surface and will
be heated. The counter-pressure roller 18 will have a
slightly flexible periphery, for example of the rubber type,
in order to be able to allow possible slight differences in
the thicknesses of the cardboard supports.
However and in contrast to conventional machines
for applying film, the flexibility of the rubberiæed surface
of the counter-pressure roller 18 must be very sligh-tly
compressible owing to the fact that it is essential -that in
the vicinity of the cut outs in the cardboard, the peripheral
surface of the counter-pressure roller 18 does not come into
contact with the glued film, all the more since it is the
glued surface which would immediately have the imprints due
to contact.
The sticking of the film to the cardboard support
is virtually immediate and moreover, the hardener present
in the glue polymerizes the latter in order that it loses
its properties of adhesion which would promote the sticking
of the impurities present in the atmosphere of the manufac-
turing workshop.
On leaving the applicator group 13, the cardboard
- :12 ~ 3~7~
suppor-t provlded with a film is carried alony by a conveyor
bel-t 19 arranged lonyitudinally in the machine 1 at the
lower level.
The product covered with film may -thus be recovered
at the outlet 20 of the machine which may for example be
equipped with a cutting device in order to separate the
various cardboard suppor-ts coated with film which are
connected to each other by the glued band of film.
However, it has been noted that if one is content
to carry out the operations described previously, the finished
product is not satisfactory owing to the fact that the
windows provided in the cardboard supports coated with film
comprise traces. Now it has been noted that by deflecting
the band 21 of cardboard supports coated with film, at the
outlet of the applicator group 13, in order to separate the
latter from -the counter-pressure roller 18, good results
were obtained as regards the finished product.
The reasons for the phenomenon cannot be clearly
explained, but it has been noted that by using various means
for deflecting the arrangement of cardboard supports coated
with film, at the outlet of the applicator group, in order
to separate this arrangement from the counter-pressure
roller 18, good results were obtained.
Figures 1 and 3 show the relatively simple means
which have been used in order to obtain this deflection.
Elowever it is quite clear that these means are not unique
and that many equivalent means could be envisaged without
diverging from the scope of the present invention.
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The means used cause pa~tial windin~ of the arranye-
ment oE cardboard supports covered with film around the
pressure roller 17, after the point of contact between this
pressure roller and the counter-pressure roller 18.
The means envisaged in Figures 1 and 3 are in the
form of a return roller 21 arranged outside the plane 22
tangential to the two rollers 17 and 18~ adjacent the
pressure roller 17. The arrangement of the cardboard
supports coated with film 23 winds partially around the
return roller 21, then, due to gravity, returns to lie
on the conveyor belt 19 in order to be discharged towards
the outlet 20 of the machine 1.
Good results have been recorded by applying glue
to the film at the rate of 20 to 24 g/m2, this glue being
of the type comprising heat sealing components and having
an incorporated hardener. This is for a film of polypropy-
lene having a thickness of 12 to 20 microns or a film of
acetate having a thickness of 14 to 17 microns.
In the case of a width of cardboard support of
approximately 0.5 metres, the force applied by the hydraulic
jack to the counter-pressure roller 18 in order to press it
against the pressure roller 17, is comprised between 1.5
and 2 tons.
As is apparent from the preceding description, the
means described for deflecting the strip of the cardboard
supports covered with film leaving the applicator group,
may be in various equivalent forms, which cannot be
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described wi-thin the framework of this description, however,
it is quite clear that the invention relates to all the
means known and within the scope of a man skilled in the
art, which would be able to bring about this deflection.
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