(19)
(11) EP 1 332 968 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Mention of the grant of the patent:
16.11.2005 Bulletin 2005/46

(21) Application number: 03100123.3

(22) Date of filing: 21.01.2003
(51) International Patent Classification (IPC)7B65B 11/02

(54)

Opposite bobbins wrapping machine and relative wrapping method

Umhüllungsmaschine mit gegenüberliegenden Rollen und entsprechendes Umhüllungsverfahren

Machine d'emballage avec des bobines opposées et procédé d'emballage correspondant


(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT SE SI SK TR

(30) Priority: 31.01.2002 IT MI20020174

(43) Date of publication of application:
06.08.2003 Bulletin 2003/32

(73) Proprietor: OFFICINA MECCANICA SESTESE S.p.A.
28040 Paruzzaro (Novara) (IT)

(72) Inventor:
  • TACCHINI, Franco
    28010, NEBBIUNO (NOVARA) (IT)

(74) Representative: Faggioni, Carlo Maria et al
Fumero Studio Consulenza Brevetti Snc Pettenkoferstrasse 20-22
80336 Munich
80336 Munich (DE)


(56) References cited: : 
WO-A-00/53497
   
       
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [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.


    Claims

    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.
     


    Ansprüche

    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. ,
     


    Revendications

    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.
     




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