[0001] The present invention relates to a wrapping machine and the respective wrapping method,
in particular a wrapping machine provided with two opposite bobbins.
[0002] As known, wrapping machines are machines apt to wrap a load in a plastic film, usually
a stretchable film. The wrapping of the load occurs by setting a rotational-translational
relative movement between a stretchable film bobbin and said load: usually this may
occur by either keeping the load fixed and moving the bobbin around it or combining
the rotation of the load with the translation of the bobbin parallel to the rotation
axis of said load.
[0003] It is also known that one of the most relevant problems of this field is that of
managing the releasing point of the film on the load to be wrapped, both at the start
and at the end of the wrapping operation. In fact, on the one hand, the free end of
the film must be made to adhere to the load in the initial phase of the wrapping,
and, on the other, in the final phase of the wrapping the terminal end of the film
must be fixed to the load, cut and re-gripped.
[0004] These operations, according to the prior art, are performed by means of a complex
gripping device that is apt to grip the end of the film, take it onto the load, keep
it in position until it is blocked by the following film layers, attach it (for example
through welding) to the final package and then separate it from the said package.
[0005] In order to do this, the gripping device is highly complex and expensive, both to
manufacture and to maintain.
[0006] Besides, in order to intervene on the film adhering to the lateral side of the load,
the gripping device must be moved from a side position to a position wherein it intercepts
the area near the load, resulting in safety problems for its users.
[0007] It is thus desirable to avoid using this kind of device.
[0008] Another problem regards the efficiency of wrapping machines, which is limited by
the maximum rotational speed (of the bobbin or of the load) which may be undertaken
in order for the machine to operate regularly. In fact, in the rotating load version,
for speeds over the typical 15 turns/minute, unbalancing torques occur which are caused
by the inevitable eccentricity of the load, while in the rotating bobbin version,
for speeds over 40-50 turns/minute, high inertial stress occurs and the so-called
"parachute effect" is produced on the stretchable film, which compromises the wrapping
stability.
[0009] Moreover, it should also be noted that the maximum rated speed cannot be reached
in a very short time, as considerable inertial masses are involved. Therefore, part
of the efficiency is lost also due to the start/stop transients.
[0010] It would thus be desirable to have a wrapping machine dispensing a higher quantity
of film per turn, so as to increase the efficiency, although within the wrapping speed
tolerance range.
[0011] WO00/53497 discloses a a film wrapping apparatus in accordance with the preamble
of claim 1 and comprising two or more wrapping heads. Film is independently drawn
from each head and attached to a point of a load by respective gripper units, then
wrapped around said load. The film is dispensed at a high rate per turn, but a plurality
of grippers is still required.
[0012] It is therefore an object of the invention to provide a multi-head wrapping machine
with a simpler construction.
[0013] Such objects are achieved by means of a wrapping machine as described in its essential
features in the appended claim 1.
[0014] According to other aspects of the invention, a joining device according to claim
5 and a load wrapping method according to claim 7 are provided.
[0015] Further characteristics and advantages of the machine according to the invention
will be evident from the following detailed description of a preferred embodiment
thereof, given by way of example and illustrated in the appended drawings, wherein:
[0016] fig. 1 is a plan view of an embodiment of the invention;
[0017] fig. 2 is a front elevation view of the embodiment of fig. 1, wherein the dispensing
units are raised;
[0018] fig. 2A is a sectional view taken along line II-II of fig. 1;
[0019] fig. 3 is a view similar to that of fig. 2, with the wrapping machine in operation;
[0020] fig. 4 is a longitudinal sectional view of a preferred embodiment of the joining
device according to the invention;
[0021] fig. 5 is a sectional view taken along line V-V of fig. 4;
[0022] figs. 6A and 6B are plan and side elevation views, respectively, of the cutting cup
mounted on the device of fig. 4;
[0023] figs. 7-18 marked with A are partial longitudinal sectional views of the device of
fig. 4 during the different knotting steps; and
[0024] figs. 7-18 marked with B are partial bottom views of the device of fig. 4 during
the different knotting steps.
[0025] In fig. 1 an exemplary wrapping machine is illustrated. It comprises two vertical
supporting columns 1a and 1b, onto which an annular structure 2 is translatably mounted,
which is designed to support and guide stretchable film dispensing units during rotation.
An annular track located on the structure is placed so as to encircle a load C to
be wrapped. These elements shall not be described more in detail, as they belong to
the prior art known to experts in the field.
[0026] According to the invention, onto the annular structure 2 two dispensing units are
mounted facing each other, a stretchable film P continuously extending between one
unit 3a to the other unit 3b (as can be seen in fig. 2). The dispensing units are
made, in a
per se known manner, of a shelf rotatively supporting a stretchable film bobbin B and a
plurality of cooperating cylinders of a pre-stretching unit.
[0027] Since the film P extends between one unit and the other along the diameter of the
annular structure, it is possible to engage it with the top portion of the load C
without using a gripping device for handling a free end of the film.
[0028] The operation of the machine according to the invention provides that the load C
be moved to a position corresponding to the rotation axis a-a' when the annular structure
2 is in its completely raised position. In this condition the film P, extending along
the diameter of the ring 2, does not intercept the load C: it is therefore possible
to provide that the two dispensing units 3a and 3b be already rotating.
[0029] After that, the annular structure 2 is lowered until the film engages the top portion
of the load C: the film P is then naturally gripped and held by the upper edges of
the load C, causing the actual wrapping to start.
[0030] Since the film application points are two at a time, it is possible to set a lager
wrapping pitch (proportional to the V/R ratio, where V = ring vertical translation
speed, and R = dispensing unit rotational speed around the load) than when a single
bobbin is used, because the wrapping cohesion is also obtained due to the partial
overlapping of the two opposite pitch lines of stretchable film (see fig. 3).
[0031] This, in brief, allows increasing the productivity, and thus achieves a first object
of the invention. The fact that the two stretchable film bobbins are continuously
joined, as seen above, right from the start does not require the wrapping cycle to
start from a stop condition of the bobbin and thus prevents most productivity losses
due to the start transient.
[0032] Furthermore, since the bobbins face each other, the machine has balanced masses,
thus resulting in less stress, and may be supported by a lighter structure.
[0033] The possibility of almost doubling the productivity relative to the prior art machines
may be exploited in order to obtain "standard" results in terms of dispensed film
per unit of time, but reducing the rotational speed of the dispensing units, thus
further reducing the stress and offering an advantageously lighter and more economical
structure. A lower rotational speed also results in a reduced parachute effect on
the film, improving the wrapping quality.
[0034] As may be guessed, once the wrapping is over, the film must be separated from the
load and restored to the initial continuous conditions. To this purpose, according
to the invention, a joining device 4 placed above the load is provided.
[0035] Due to the fact that the film extends along the diameter of the annular structure
2, it is very easy to determine, in the rotational centre, a sole film joining point
wherein the joining device is to be placed.
[0036] It follows that the joining device 4 may avoid using complicated feelers or other
film locating and gripping elements.
[0037] According to a preferred embodiment of the invention, the joining device 4 is mounted,
at the rotational axis a-a', onto a frame 5 placed above the annular structure 2.
The frame is translatably mounted onto columns 1a and 1b (fig. 2A). For example, the
ring 2 and the frame 5 may be both mounted on respective supporting shelves engaged
with a common fixed chain 6 (only a portion of which is shown in fig. 2A). During
the raising step, the frame 5 is lying upon the upper part of the annular structure
2. Once the desired height is reached, a suitable ratchet 7 prevents the relative
movement between the frame 5 and the chain 6, so as to keep the joining device 4 in
position in spite of possible lowerings of the ring 2.
[0038] The joining device 4 must be apt to join the two film ends coming from the load,
once the wrapping is over, separate them from the respective bobbins and rejoin the
free ends of the two bobbins in order to restore the initial conditions.
[0039] This operation may be done with different techniques, for example by welding, gripping,
stapling, gluing, etc. Hereinafter, a preferred embodiment of the joining device will
be illustrated, with reference to figs. 4-18B.
[0040] In fig. 4 a preferred joining device is illustrated in detail. It is made of a housing
and supporting structure 10, wherein there are a main gripping element 11 and a pair
of secondary grippers 12a and 12b, which are placed opposite relative to the main
gripping element 11. The housing structure has a protective casing 10a at its lower
end, from which several gripping elements may project.
[0041] The secondary grippers 12a and 12b are mounted onto fifth wheel means 13 allowing
the concentrical rotation thereof relative to the main gripping element 11. The fifth
wheel means 13 are made to rotate, for rotation angles of ±180°, by means of a driving
element 14 and a drive chain 14a (fig. 5).
[0042] The secondary grippers are made of gripping pins 15a and 15b that are translatable,
through actuators 16a and 16b, within small hollow cylinders 17a and 17b.
[0043] The main gripping element 11 is made of a main gripping pin 18 that may slide, through
an actuator A1, within a hollow pin or cylinder 19 which, integrally with the actuator
A1, may in turn slide within a liner 20 by means of a second actuator A2.
[0044] A cutting cup 21 is further integrally connected to the liner structure 20, in a
concentrical position relative to the main gripping element 11. Said cutting cup 21
is well illustrated in figs. 6A and 6B: it is made of protective cylindrical walls
21a, interrupted by windows onto which cutting blades 21b are mounted at opposite
facing edges.
[0045] The combination of the gripping operations of the four actuators 16a, 16b, A1 and
A2, together with the alternate rotation of the two secondary grippers is apt to produce
a knot in the stretchable film, separating it from the load and forming again another
joining knot in order to start a new wrapping cycle. This operation is hereinafter
illustrated in detail.
[0046] The joining device is moved close to the top of the load C; initially, the secondary
gripping pins 15a and 15b are inwardly withdrawn (i.e. not projecting from the lower
profile of the casing 10a), while the main gripping element 11 is in its completely
extracted position. This way, the two bobbins, while rotating and vertically rising,
also apply some turns (2 or 3) of stretchable film onto the external surface of the
cylinder 19, then further rise upwards before being stopped. In this condition, which
is illustrated in fig. 7A, two portions of film come upwardly from the load C, wrap
the cylinder 19 in a plurality of turns and then move upwards in the direction of
the respective bobbins B.
[0047] At this point, the cylinder 19 is raised until the film turns are abutting against
the mouth of the liner 20. The gripping pin 18 is then lowered, which pin is provided
with a gripping flange 18a, and then the bobbins are made again to rotate around the
axis a-a' in order to apply at least a further turn of film below the previous ones
(fig. 8A).
[0048] At this point, also the gripping pins 15a and 15b of the secondary grippers are lowered
and the film P is wrapped around them by a certain angle apt to guarantee a good retaining
effect once the gripper is closed again (fig. 9B).
[0049] Until this moment the film passes always below the profile of the casing 10a and
of the cutting cup 21.
[0050] Subsequently, the gripping pins 15a and 15b are closed and, during this clamping
operation, they drag and block the film P. Since the gripping plane of the pins15a
and 15b is placed at a higher level than the lower profile of the casing 10a and of
the cup 21, the film P, stretched into a cord, is moved inside the windows of the
cup 21 (see figs. 10A and 10B). At the same time, also the central gripping pin 18
clamps the last turn of film P applied against the edge of the cylinder 19.
[0051] At this point the actuator 14 is operated in order to make the two secondary gripping
pins rotate according to the arrows G (fig. 11B).
[0052] As soon as an angle of about 30° is covered, the two portions of film extending between
the central pin and the two secondary pins intercept the two cutting blades 21b, getting
cut (fig. 12B): in this cutting step, the film coming from the wrapped up load C (whose
ends remain hanging from the central gripping pin) is separated from the two film
portions coming from the two bobbins (which remain gripped and held by the two secondary
pins).
[0053] Then the cylinder 19 together with the gripping pin 18, between which the last turn
of film is clamped, integrally rise up along liner 20, moving the last turn of film
inside and above the previously applied turns: this way, a raw knot is obtained which,
also by exploiting the elasticity of turns material, establishes a stable junction
between the two ends of the film coming from the wrapped load C (fig. 13B).
[0054] Meanwhile, the two secondary pins have completed a rotation of about 180° in the
direction of the arrow G.
[0055] Subsequently, the main pin 18 and cylinder 19 are lowered again (fig. 14A) in order
to apply some new turns (2 or 3) of stretchable film through a further rotation of
the two bobbins. Then the step described with reference to figs. 9 and 10 is again
performed, i.e. the cylinder 19 rises until pushing the layers against the edge of
the liner 20, while the pin 18 is lowered by a small section. A portion of the film
held by the secondary grippers is wrapped on this latter section of the pin, forming
at least one half-turn: this is obtained by means of an inverted rotation of about
180° (in the direction of he arrow G') of the two gripping pins 15a and 15b (fig.
15B). The latter rotation is possible, despite the film cord being clamped at both
ends, due to the film high elasticity. In this counter-rotation there is no risk of
the film getting cut by the blades 21b because, in this rotation direction, the cup
21 has a shielding function.
[0056] The gripping pin 18 is then lifted and the last half-turn is gripped between the
flange 18a and the mouth of the cylinder 19. The film ends that are still held by
the secondary pins may be freed (fig. 16B) and the actuator A2 is again operated in
order to perform a knot - identical to the previously described one - also between
these latter turns (figs. 17A and 17B): this way, the continuity of the film extending
between the opposite bobbins is restored (fig. 18B), so that the initial conditions
are reestablished in order to perform a new wrapping cycle.
[0057] An expert in the field will clearly appreciate that the above described joining device
and method should not be intended as limiting the invention, but only represent a
preferred embodiment thereof.
[0058] By means of a generic joining device, according to the teachings of the invention,
it is possible to join the free ends of the film to the wrapped load, without using
complicated feeling devices nor gripping systems that should be moved transversely
relative to the wrapping machine, thus a further object set out is achieved.
[0059] Moreover, the central position of the joining device allows it to be incorporated
into another equipment useful for the wrapping, for example a so-called "small press"
for unstable loads.
[0060] The specific joining device illustrated in the preferred embodiment advantageously
allows to join the film ends by knotting them: this technique is much more reliable
and less unstable than the traditional welding technique, thus resulting in a further
advantage.
1. Wrapping machine of the type comprising at least a pair of opposed stretchable film
dispensing units (3a, 3b) mounted in rotation-translation around a load (C) to be
wrapped, the stretchable film coming from the first unit being connected to that of
the second unit at least during a wrapping step, characterized in that it further comprises a joining device (4) apt to intercept, at the rotation axis,
the film portions extending between the load (C) and the opposite film dispensing
units (3a, 3b), to separate them and to re-establish the continuity of the film portions
extending between the opposite units and of the film portions coming from the wrapped
load.
2. Machine as in claim 1), wherein said joining device (4) is apt to cut said film portions
and to knot the freed ends thereof.
3. Machine as in claims 1) o 2), wherein said dispensing units (3a, 3b) comprise at least
one stretchable plastic film bobbin (B) and a pre-stretching unit and are mounted
rotating on an annular track structure translatable, relative to the load (C) along
the rotation axis.
4. Machine as in claim 3), wherein said joining device is mounted on a vertically translatable
frame (5) apt to bear above the annular track structure (2), but disengageable therefrom
and blockable along the vertical direction.
5. Joining device for intercepting and joining plastic film portions extending between
two opposed bobbins in a wrapping machine as in claim 1), comprising
a main central gripping element (11), comprised of a gripping pin (18) slideable
within a hollow cylinder (19) which in turn is slideable within a liner (20), and
a pair of secondary grippers (12, 12b), placed opposite each other relative to
the main gripping element (11) and apt to integrally pivot around the longitudinal
sliding axis of said main gripping element (11) to perform a knotting sequence on
said plastic film portion.
6. Joining device as in 5), further comprising blade means (21b) arranged between said
main gripping element (11) and said secondary grippers (12a, 12b) and apt to intercept
and severe said film in a specific step of said knotting sequence.
7. Load wrapping method, wherein at least a pair of opposite stretchable film dispensing
units (3a, 3b), is made to rotate and translate around the load (C) in order to obtain
a series of wrapping turns of film, characterised in that the film from the first unit is joined to the film from the second unit at least
before and during the load wrapping operation, then separated after wrapping operation
and re-joined before the start of next wrapping operation.
8. Wrapping method as in claim 7), wherein the pair of dispensing units (3a, 3b) is made
to rotate before the start of the wrapping operation, in a position such that the
assembly of the two units and the film extending between them does not interfere with
the load when the load is introduced into the wrapping machine at the rotation axis
of said pair of dispensing units.
9. Wrapping method as in claims 7) or 8), wherein, at the end of the wrapping operation,
the two film ends coming from the load and directed to the dispensing units (3a, 3b)
are cut and re-joined in order to restore the film continuity between the two dispensing
units and between the two ends coming from the wrapped load.
10. Wrapping method as in claim 9), wherein said rejoining step for restoring the film
continuity involves knotting the film ends.
1. Verpackungsmaschine der Bauart, die zumindest ein Paar von einander gegenüberstehenden
Einheiten zur Abgabe von dehnbarem Film aufweist, die drehbar und translatorisch bewegbar
um eine zu verpackende Ladeeinheit gehalten sind, wobei der dehnbare Film, der von
der ersten Einheit kommt, mit dem der zweiten Einheit während zumindest eines Verpackungsschritts
verbunden wird, dadurch gekennzeichnet, daß die Maschine weiterhin eine Verbindungsvorrichtung aufweist, die in der Lage ist,
die Filmabschnitte, die sich zwischen der Ladeeinheit und den gegenüberstehenden Einheiten
zur Abgabe von Folie erstrecken, an der Drehachse aufzugreifen, sie zu trennen und
die Kontinuität der genannten Folienabschnitte, die sich zwischen der Ladeeinheit
und den gegenüberstehenden Einheiten erstrecken, erneut herzustellen.
2. Maschine nach Anspruch 1, dadurch gekennzeichnet, daß die genannte Verbindungsvorrichtung in der Lage ist, die genannten Filmabschnitte
zu schneiden und die freien Enden davon zu verknoten.
3. Maschine nach den Ansprüchen 1 oder 2, dadurch gekennzeichnet, daß die genannten Abgabeeinheiten zumindest eine Spule mit dehnbarer Kunststoffolie und
eine Vordehnungseinheit umfassen und drehbar auf einer Struktur mit ringförmiger Bahn
gehalten sind, die relativ zu der Ladeeinheit entlang der Drehachse verfahrbar ist.
4. Maschine nach Anspruch 3, dadurch gekennzeichnet, daß die genannte Verbindungseinheit auf einem in vertikaler Richtung verfahrbaren Rahmen
gehalten ist, der geeignet ist, von oben auf der Struktur mit ringförmiger Bahn aufzuliegen,
aber von dieser lösbar ist und entlang der vertikalen Richtung blockiert werden kann.
5. Verbindungsvorrichtung zum Aufgreifen und Verbinden von Kunststoffolienabschnitten,
die sich zwischen zwei gegenüberstehenden Spulen in einer Verpackungsmaschine nach
Anspruch 1 erstrecken, dadurch gekennzeichnet, daß die Vorrichtung ein zentrales Hauptgreiferelement (11) aufweist, das aus einem Greifzapfen
(18) besteht, der innerhalb eines hohlen Zylinders (19) verschieblich ist, der seinerseits
innerhalb einer Auskleidung (20) verschieblich ist, und ein Paar von sekundären Greifern
(12, 12b), die einander gegenüberliegend relativ zu dem Hauptgreiferelement (11) angeordnet
sind und dazu geeignet sind, einheitlich um die longitudinale Verschiebeachse des
genannten Hauptgreiferelements (11) zu verschwenken, um einen Verknotungsvorgang an
dem genannten Kunststofffolienabschnitt auszuführen.
6. Verbindungsvorrichtung nach Anspruch 5, weiter gekennzeichnet durch ein Schneidklingenmittel (21b), das zwischen dem genannten Hauptgreiferelement (11)
und den sekundären Greifern (12a, 12b) angeordnet ist und dazu geeignet ist, die genannte
Folie in einem bestimmten Schritt des genannten Verknotungsvorgangs aufzugreifen und
abzutrennen.
7. Verfahren zum Verpacken einer Ladeeinheit, bei dem zumindest eine Einheit zum Abgeben
einer dehnbaren Folie dazu gebracht wird, um die Ladeeinheit zu rotieren und sich
translatorisch zu bewegen, um eine Reihe von Verpackungswindungen der Folie zu erhalten,
dadurch gekennzeichnet, daß eine zweite Abgabeeinheit dazu gebracht wird, in einer Stellung entgegensetzt zu
der Stellung der ersten Abgabeeinheit zu drehen und sich translatorisch zu bewegen,
wobei die Folie von der ersten Einheit mit der Folie von der zweiten Einheit zumindest
vor und während des Verpackungsvorgangs der Ladeeinheit verbunden wird, dann nach
dem Verpackungsvorgang getrennt wird und vor dem Beginn eines nächsten Verpackungsvorgangs
erneut verbunden wird.
8. Verpackungsverfahren nach Anspruch 7, dadurch gekennzeichnet, daß das Paar von Abgabeeinheiten vor dem Start des Verpackungsvorgangs dazu gebracht
wird, sich zu drehen, in einer solchen Position, daß die aus den beiden Einheiten
und der sich zwischen diesen erstreckenden Folie bestehende Einheit nicht in störendes
Zusammenwirken mit der Ladeeinheit kommt, wenn die Ladeeinheit in die Verpackungsmaschine
eingeführt wird, an der Drehachse des genannten Paars von Abgabeeinheiten.
9. Verpackungsverfahren nach Anspruch 7 oder 8, dadurch gekennzeichnet, daß am Ende des Verpackungsvorgangs die beiden Folienenden, die von der Ladeeinheit kommen
und zu den Abgabeeinheiten gerichtet sind, abgeschnitten und erneut miteinander verbunden
werden, um die Kontinuität der Folie zwischen den beiden Abgabeeinheiten und zwischen
den beiden Enden, die von der verpackten Ladeeinheit kommen, wieder herzustellen.
10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, daß der genannte Schritt des erneuten Verbindens zum Wiederherstellen der Kontinuität
der Folie ein Verknoten der Enden der Folie mit sich bringt. ,
1. Machine d'emballage du type comprenant au moins une paire d'unités de distribution
de film étirable opposées (3a, 3b), installées pour effectuer un mouvement de translation
et de rotation autour d'une charge (C) devant être emballée, le film étirable provenant
de la première unité qui est relié à celui de la seconde unité au moins durant une
étape d'emballage, caractérisée en ce qu'elle comprend en outre un dispositif de réunion (4) pouvant intercepter, au niveau
de l'axe de rotation, les parties du film s'étendant entre la charge (C) et les unités
de distribution de film opposées (3a, 3b) pour les séparer et rétablir la continuité
des parties du film s'étendant entre les unités opposées et celle des parties du film
provenant de la charge emballée.
2. Machine selon la revendication 1, dans laquelle ledit dispositif de réunion (4) peut
couper lesdites parties de film et nouer les extrémités libres de celles-ci.
3. Machine selon les revendications 1 ou 2, dans laquelle lesdites unités de distribution
(3a, 3b) comprennent au moins une bobine de film de matière plastique étirable (B)
et une unité de pré-étirage, qui sont montées pour tourner sur une structure de chemin
de roulement annulaire (2), en pouvant effectuer un mouvement de translation par rapport
à la charge (C) le long de l'axe de rotation.
4. Machine selon la revendication 3, dans laquelle ledit dispositif de réunion est monté
sur un châssis pouvant effectuer un mouvement de translation vertical (5), pouvant
porter au-dessus de la structure de chemin de roulement annulaire (2), mais pouvant
se détacher de celle-ci et se bloquer le long de la direction verticale.
5. Dispositif de réunion destiné à intercepter et réunir les parties de film plastique
s'étendant entre deux bobines opposées dans une machine d'emballage selon la revendication
1, comprenant
un élément de saisie central principal (11), constitué d'une broche de saisie (18)
pouvant coulisser à l'intérieur d'un cylindre creux (19) qui à son tour peut coulisser
à l'intérieur d'une chemise (20), et
une paire de pinces secondaires (12a, 12b) placées à l'opposé l'une de l'autre
par rapport à l'élément de saisie principal (11) et pouvant pivoter en totalité autour
de l'axe de coulissement longitudinal dudit élément de saisie principal (11) afin
d'exécuter une séquence de nouage sur ladite partie de film plastique.
6. Dispositif de réunion selon la revendication 5, comprenant en outre des moyens de
lames (21b) disposés entre ledit élément de saisie principal (11) et lesdites pinces
secondaires (12a, 12b) et pouvant intercepter et couper ledit film en une étape spécifique
de ladite séquence de nouage.
7. Procédé d'emballage d'une charge, où au moins une paire d'unités de distribution de
film étirable opposées (3a, 3b) est amenée à tourner et à effectuer un mouvement de
translation autour de la charge (C), de manière à obtenir une série de tours d'emballage
du film, caractérisé en ce que le film provenant de la première unité est lié au film provenant de la seconde unité
au moins avant et pendant l'opération d'emballage de la charge, puis est séparé après
l'opération d'emballage et réuni avant le début de l'opération d'emballage suivante.
8. Procédé d'emballage selon la revendication 7, dans lequel la paire d'unités de distribution
(3a, 3b) est amenée à tourner avant le début de l'opération d'emballage, dans une
position telle que l'ensemble des deux unités et du film s'étendant entre celles-ci
n'interfère pas avec la charge lorsque la charge est introduite dans la machine d'emballage
au niveau de l'axe de rotation de ladite paire d'unités de distribution.
9. Procédé d'emballage selon les revendications 7 ou 8, dans lequel, à la fin de l'opération
d'emballage, les deux extrémités du film provenant de la charge et dirigées vers les
unités de distribution (3a, 3b) sont coupées et réunies de manière à rétablir la continuité
du film entre les deux unités de distribution et entre les deux extrémités provenant
de la charge emballée.
10. Procédé d'emballage selon la revendication 9, dans lequel ladite étape de réunion
destinée à rétablir la continuité du film implique le nouage des extrémités du film.