EP1379457A1

EP1379457A1 - Method for recharging a bundling machine using a plastic film and bundling machine carrying out said method

Info

Publication number: EP1379457A1
Application number: EP02722388A
Authority: EP
Inventors: Laurent Mace; François GOSSET
Original assignee: Cermex Ouest Conditionnement SAS
Current assignee: Sidel Packing Solutions SAS
Priority date: 2001-04-10
Filing date: 2002-04-02
Publication date: 2004-01-14
Anticipated expiration: 2022-04-02
Also published as: ATE323658T1; WO2002083533A1; US20080092493A1; ES2261661T3; US7326308B2; EP1379457B1; FR2823190A1; PT1379457E; DE60210759D1; FR2823190B1; DE60210759T2; US20040103977A1

Abstract

The procedure for re-loading a machine fed by an injector mechanism with a film cutter consists of fitting a stand-by roll of wrapping film in the machine while a previous roll is being used and placing the free end of the stand-by roll in readiness inside the injector/cutter. Once the end of the film from the previous roll reaches a given position it is stopped and replaced by the free end of the stand-by roll's film. The procedure for re-loading a machine used for wrapping batched of products (1-4) in plastic film (5) fed by an injector mechanism (17) with a film cutter consists of fitting a stand-by roll (70) of wrapping film in the machine while a previous roll (7) is being used and placing the free end (52) of the stand-by roll in readiness inside the injector/cutter. Once the end of the film from the previous roll reaches a given position in the machine it is stopped and replaced by the free end of the stand-by roll's film. The old roll (7) is then removed from the machine and replaced by a fresh stand-by roll, so that the wrapping procedure can operate continuously.

Description

Method for recharging a shrinkwrapper using a plastic film, and shrinkwrapper implementing the method.

The invention relates to improvements to methods for reloading machines for producing packaging in plastic films, also called shrink wrapping machines or shrinkwrappers, using such films. It relates more particularly to a process allowing rapid loading of the film, and to machines implementing this process. Film packaging of products is a widespread technique, which allows several products to be grouped together, such as bottles, flasks, boxes, jars, or any other type of object. This technique makes it easier to transport products to a place of final destination where the packaging is removed. Depending on the type of products packaged, either the film is the only element of the packaging, or it is associated with additional elements, such as plates, trays or the like on which the products are placed before being wrapped in film. .

The machines intended for constituting such packages are called shrinkwrappers. They make it possible to surround each group of products with a section of film. To this end, they comprise, on the one hand, a device for feeding the groups of products to be packaged, such as a conveyor, and, where appropriate, a device for feeding the ancillary elements, and, on the other hand, a reel. film dispenser, a device for directing a first end of the film towards each group of products to be packaged, devices for placing the film around the group of products in synchronism with the advancement of the film, devices for cutting the film film when a section of sufficient length is obtained and devices for closing the film around the group of products.

In some machines, the film used is heat shrinkable, and the closure is effected by clamping the film in a film heat shrink tunnel. In other machines, the closure is carried out by heat sealing or gluing.

The device for directing a first end of the film towards the group of products to be packaged, also called film injection device, comprises for example drive rollers between which the film is arranged, and, downstream of these rollers, in the direction of advancement of the film, a gripping member. The film, entrained between the rollers, is then gripped by the gripping member which directs it towards a conveyor or a table on which the group of products is located, and which makes the film undergo a movement allowing it to surround the group of products. In addition, when a sufficient length of film to form a section enabling the group of products to be surrounded has been unrolled, the film is cut, so that a section of film is completely available for packaging the group of products, and the rest of the film can be used to pack the following groups of products by repeating the operations mentioned.

Generally, and very particularly in the machines of the applicant, the cutting means are associated with the injection device. In fact, the latter comprises, a first arrangement, called upstream, of two rollers in tangential contact with each other, one of the rollers being driving, the other driven, and a second arrangement, called downstream, identical in the first, two other rollers also in tangential contact, with a driving roller and a driven roller, and the cutting means are arranged between the two arrangements. The film is arranged so as to pass between the two rollers of each arrangement, and is driven by the pressure which is exerted between the two rollers of the same arrangement. The cutting means are activated at the appropriate times, in synchronism with the machine cycle.

These machines require that the film dispensing reel be replaced regularly, when the entire available length of film has been consumed. For this purpose, the machines include a device for storing a full waiting dispensing reel on which said reel is put in place while another dispensing reel is being unwound, and the change of dispensing reel involves stop the packaging operations, and heat seal the beginning of the film of this full reel with the end of the film of the ending reel.

In the machines of the applicant, by way of indication, for the groups of medium-sized products which they allow to be packaged, the change of the distribution coil takes place approximately every twenty minutes, and the stop and welding steps that this change implies last about twenty seconds if they are correctly and smoothly carried out. It is therefore approximately at least the equivalent of making one minute of packaging that is lost every hour due to the reel changes.

The above is valid for films free of decorations which do not require precise positioning with respect to each other before welding; on the other hand, there are decorated films which require that the patterns of one be aligned with the patterns of the other before welding, which prolongs the operations.

In fact, contrary to what one might think, it is not the fact of heat sealing the start end of the film of the full reel with the end of the film of the previous reel which consumes the most time . On the contrary, this operation saves time compared to that which would consist in letting all the previous film spin before reloading the machine with a new dispensing reel. Indeed, between the area of the machine where the distributor coil is disposed and the injection device, there is a compensation mechanism, with an arrangement of compensating rollers, mounted on an articulated device, called a puppet, which makes it possible to adjust the film travel speed and speed to take into account that the packaging operations are not carried out at constant film travel speed. This mechanism, thanks to its rollers, makes the film undergo a relatively complex, and in any case not linear, path between the distributor reel and the injection device, so that if all the film had to be spun, then at the time of reloading, the new film should be positioned correctly with respect to the arrangement of compensating rollers, then engage it in the injection device by wedging it correctly to prevent it from coming out crumpled or offset laterally from the latter . These operations would take even longer to complete.

Thus, by heat-sealing the end of a previous film at the start of the new one, the latter is immediately correctly positioned in the compensation mechanism and engages in the injection device driven by the rest of the film from the previous reel.

However, for the operation to be carried out smoothly, the operator must still be present at the appropriate time, that is to say when the end of the film is approaching. To this end, known machines include means for detecting the approach of the end of the film on the dispensing reel during unwinding, which determine the remaining length of film on this reel and trigger when it becomes less than a value. predetermined. In fact, since it is difficult to detect a length of film wound on a reel, the means rather detect the remaining thickness of film on the dispensing reel, which is a function of the remaining length.

These detection means can be coupled to means for alerting the operator, who, from the moment he is warned, takes manual control of the machine, and monitors the unwinding of the end of the distribution reel, then stops the machine at the appropriate time and performs the heat sealing operation, before restarting the machine then removing the empty coil and putting a full one on hold. With this operating mode, if the operator is absent at the time of the warning, the risk is that the distribution reel will unwind completely and that the film will come off completely, implying that the machine must be fully recharged with the new film, this that is to say by positioning it correctly with respect to the arrangement of the compensating rollers, then by engaging it again in the injection device. Alternatively, the detection means can be coupled to means for stopping the film. This assumes that the operator resumes manual control of the machine after the film has stopped, then monitors the unwinding of the end of the dispensing reel, and stops the machine at the appropriate time to perform the heat-sealing operation, before restarting then remove the empty spool and put a full one on hold. With this operating mode, if the operator is absent at the time of stopping, the risk is an additional loss of time. The invention aims to remedy these drawbacks. According to the invention, a method for recharging a machine for packaging groups of products using a plastic film intended for said packaging, said machine comprising on the one hand means for injecting and cutting the film. supplied with film from a distribution reel, located upstream, in the direction of travel of the film, injection and cutting means, and on the other hand means for storing a full reel, also upstream means of injection and cutting, the method being of the type according to which, after detection of the approach of the end of the film of the distribution reel, various steps are carried out which make it possible to finish unwinding and emptying it, and to engage the film of the full coil in the injection means, so that the latter becomes distributor in turn, then the one which has been emptied is replaced by a new full coil, is characterized in that it consists: while a coil is being dispensed, placing a full reel in the machine and keeping the free end of the start of the film connected to this full reel at the inlet of the injection and cutting means; after having detected that the end of the film end of the reel being dispensed reaches a predetermined position in the machine, to stop the progression of the film of this reel in the injection and cutting means, and to cause the entrainment in the latter of the free end of the film connected to the full reel, so that the latter becomes a distributor; while the latter is being distributed, to replace the one which has been emptied by a new full reel, and to maintain at the entry of the injection and cutting means the free end, of the beginning of the film connected to this new reel, and repeat the above cycle with the new reel, when the end end of the reel film being dispensed, in turn reaches a predetermined position in the machine. Thus, at the very moment of the reel substitution, it eliminates the need to weld the end of the film of the reel which has just been emptied with the beginning of that of the full reel and there is therefore no time out during substitution. In addition, this operating mode makes it possible to automate the substitution operation, which reduces the constraints of the operator, who no longer necessarily has to act immediately after the detection of the end of the approach of the end of the film of a reel. The operator then has all the time it takes to replace the coil which has just been emptied with a full one.

In one implementation, the entire film of the reel being dispensed, and the predetermined position, which is detected, from the end of the end of the film of this reel, in the machine is that where said end of film leaves the injection and cutting means.

Thus, the free end of the beginning of the film connected to the full reel is brought into the injection and cutting means when the film of the other has been completely consumed.

This implementation removes the welds from one film to another.

However, it implies, at each reel change, to reposition the film of the full reel at the inlet of the injection and cutting means and in the compensation mechanism. This maneuver is quite possible in the time taken by a coil to unfold completely. But it is tedious and occupies the operator a large part of his time.

This is why, in a preferred implementation, when a reel ends, the entire film is not spun, but a part of it is kept on the machine, which is welded, in masked time, at the start of 'a full reel. We therefore come to connect the end of the remaining part of a film to the start of the film of a full reel, and it is therefore the remaining part which drives the film of the full reel when it is put into service.

To this end, according to another characteristic, the method consists in monitoring the passage of the end end, of the film of the reel being dispensed, in the machine, in a predetermined position located between the reel and the means of injection and cutting, and; when the passage in this position is reached, to stop the progression of the film of this reel in the injection and cutting means, so that there remains a remaining portion of film between said end of the end of the film and the means of injection and cutting, and to cause the entrainment therein of the free end of the film connected to the full reel, so that the latter becomes a distributor; remove the empty spool and place a new full spool instead; soldering the beginning of the film from the full reel to the end of the remaining part of the film from that which has been removed.

Thus, apart from the removal of an empty coil and the establishment of a full one, this implementation requires only welding in masked time, while a coil is being unwound. This leaves time for the operator to carry out this operation with precision, even in the case of films with decorative patterns; in addition, the weld has time to cool properly and there is no longer a complex and complex operation to replace the film, since the new one is driven by a remaining part, waiting.

In one implementation, the detection of the predetermined position of the end of the film from the reel during distribution is carried out in two stages: a first in which the remaining length of film wound on this reel is evaluated approximately during distribution, then when a predetermined value is reached, the film progression of this reel is stopped in the injection and cutting means, the full reel is put into service by causing the drive, in these injection and cutting means , from the free end of the film connected to this full reel, so that the latter becomes a distributor and the other is stopped; and a second step in which the remaining length of the film wound on the idle reel is precisely determined, after which a) if the remaining length of film on this idle reel is sufficient to continue packaging groups of products , we stop the progression of the film of the other, distributor, in the injection and cutting means, we cause the drive, in the latter, of the free end of the film connected to the reel which was in waiting, so that it becomes distributor again, and the passage of the upstream end, the end, of the film of this reel is monitored in the machine, in said predetermined position located between the reel and the injection means and cutting, and; when the passage in this position is reached, the film progression of this reel is again stopped in the injection and cutting means, the free end of the film connected to the film is caused to drive in the latter 'other reel, so that it becomes distributor again; remove the empty reel and place a full reel instead; the start of the film from the full reel is welded to the end end of the remaining part of the film from the removed reel, and it is waited until the remaining length of film wound on the second requires a new reel change; b) if the remaining length of film on this idle reel is insufficient to continue to pack groups of products, we continue to pack with the film on the other reel, until it is assessed that the remaining length of film wound on it requires a new reel change and, during this time, the end end of the film from the first reel is brought into the machine in the said predetermined position located between the reel and the injection and cutting means, and the empty coil is removed and a full coil is placed instead; the start of the film from the full reel is welded to the end end of the remaining part of the film from the reel which has just been removed and; we repeat the previous operations by passing from one reel to another.

This operating mode makes it possible to take into account the difficulty that there is in measuring the remaining length of the film on a reel when the latter takes place, while avoiding losing film. It is easier to make an approximate determination of the remaining length of film, for example, as indicated above, by evaluating the remaining thickness of film wound on the reel. The evaluation can only be approximate, inter alia due to the vibrations of the machine and because there are certain tolerances on the very thickness of the film during its manufacture.

The approximate evaluation of the remaining length of film wound on the reel being dispensed and the commissioning of the full reel can be carried out by the operator himself; however, to allow the operator to perform other actions and to prevent the reel from unwinding completely in the event that the operator is absent, automatic evaluation and automatic change are preferred.

When a reel is stopped, precise determination of the remaining length is easier. Again, this determination can be made by the operator or automatically; the same applies to the possible return to use of this coil in the event that a sufficient length remains.

Finally, the monitoring of the passage of the upstream end, of the end, of the film of the reel being dispensed in the machine, in said predetermined position, can be carried out by the operator or automatically. According to another characteristic, the machine comprising a compensation mechanism between each coil and the injection and cutting means, the predetermined position located between the coil and the injection and cutting means is monitored so that the progression of a reel being dispensed is stopped when the end of the film carried by this reel is between the reel and the corresponding compensation mechanism. In this way, after the welding has been carried out, the remaining part of the film of a reel is used to engage the film of a new reel in the compensation mechanism. Thus, apart from the rare cases where a film is released from the compensation mechanism, which can occur following a machine maintenance operation or an accidental tear of a film, film change operations do not take very little time for the operator who can focus on other tasks required by the machine.

A device for implementing the method is characterized in that it comprises two arrangements for alternately distributing the film from one reel and from the other to the injection and cutting means, which arrangements include means, known as drive and holding, arranged to hold the free end of the film of the reel on standby at the inlet of the injection and cutting means, and to allow the film of the dispensing reel to be driven in the means of injection and cutting.

According to another characteristic, the arrangements are identical. In one implementation, the injection and cutting means are constituted by a single device comprising, at its entry, film drive rollers, and the drive and holding means consist of two separate devices arranged upstream of the input of the single injection and cutting device, and the machine is arranged so that, after having stopped the progression of the film of a reel being dispensed in the injection and cutting means, the direction of progression of this film is reversed in the said means, so as to free the free end from the start, and it is maintained with the corresponding drive and holding device, then the end is driven free, at the start of the film on hold, to the injection and cutting with the other corresponding drive and holding device.

In an implementation variant, the injection and cutting means are constituted by two separate devices which each receive the film from a reel, and each comprise, at their input, film drive rollers, and the drive and holding means are constituted by the drive rollers, located at the entrance of the injection and cutting devices, and the machine is arranged so that the progression of the film of a reel during distribution in an injection and cutting device is stopped by stopping the rotation of its input drive rollers, and the drive of the free end, from the start of the film on hold, in the other injection device and cutting is caused by rotating its input drive rollers.

Other characteristics and advantages of the invention will appear on reading the description which follows, made with reference to the appended figures, in which:

- Figure 1 is a schematic side view of a machine for implementing the method;

- Figures 2 to 4 are schematic side views of various alternative embodiments of the machine part which allows the film of one reel or the other to be used.

The invention can be implemented on any known wrapping machine. Thus, in Figure 1, is schematically illustrated the application of the invention to a machine for packaging groups of products 1, 2, 3, 4 using plastic film 5, which is made integral a group of products around which it has been wound up using any suitable device 6, such as a heating tunnel when the plastic material used is heat shrinkable, or a heat sealing device or a device of gluing, as mentioned in the preamble. The device of Figure 1 is arranged to avoid having to reload the compensating rollers at each change of reel.

The film 5 is distributed from a distributing reel 7 and is directed towards the wrapping zone 8 into which, in known manner, the groups of products are brought, for example using a belt 9 carrier ; similarly, they leave it with the aid of another belt 1 0 which drives them towards the closure device 6.

On its path from the dispensing reel 7 to the wrapping area 8, the film encounters guide devices such as rollers 1 1, 12, 13 which, for some of them 1 1, 1 2, are compensating rollers contributing , in addition to their guiding function, to adjusting the tension of the film at the end and as it unwinds from the dispensing reel 7. To this end, the rollers 1 1, 1 2, are attached to movable mechanisms 1 4, 1 5, called puppets. Downstream of the guide devices 1 1, 12, the film 5 passes through a device 1 6 which, in accordance with the invention, can be produced according to several variants, which will be described in detail later. The device 1 6 comprises, inter alia, the means 17 for injecting and cutting the film. In Figure 1, the injection and cutting means are constituted by a single device, whose structure, known per se, comprises, a first arrangement, called upstream, of two rollers 1 8, 1 9, called injection , in tangential contact with each other, one 1 8 for example coach, the other 1 9 driven, and a second arrangement, called downstream, identical to the first, of two other rollers 20, 21, called pressure, also in tangential contact, with a driving roller 20 and a driven roller 21. The film is placed between the two rollers of each arrangement, and is driven by the pressure exerted between the two rollers of the same arrangement. In the area of the machine delimited between these two arrangements, the means 1 7 for injecting and cutting the film comprise a device with a member 22 for cutting the film.

The film cutting member 22, in order to produce the successive sections, is constituted, in a known manner, by a sharp blade carried by a bar 23 which can rotate around its longitudinal axis as illustrated by the arrow 24. The member 22 , here the blade, and the bar constitute the cutting device as such, which device is controlled by the control mechanism of the machine according to the desired length of the sections of film necessary to surround the groups of products. To cut the film, the bar 23 is rotated so that the edge of the blade crosses the thickness of the film during its movement.

To this end, the bar 23 is connected to means for causing it to rotate at appropriate times as a function of the advance of the film in the machine. Thus, in one implementation, the means for causing the rotation consist of a motor, not shown, which can be sequentially controlled; alternatively, the rotational movement is caused using a cam mechanism connected for example to the drive mechanism of the rollers 1 8, 20 drivers. The means for causing the rotation of the bar can be connected to it directly or by means of a return mechanism.

Thus, in known manner, at the moment when the film is cut, two portions of film appear: a first 50 forming a section for packaging a group 3 of products, and a second 51 integral with the dispensing reel 7. The first portion 50 is directed towards a group 3 of products using a mobile guide device 25, known per se, and constituted for example by an arrangement of bars which come to grip the film at its exit from the arrangement downstream of pressure rollers 20, 21, and subject it to an appropriate path, symbolized by the broken line 26 to surround the group 3 of products, while the second portion 51 continues to be driven by the arrangement of the two rollers 1 8 , 1 9 injection upstream of the means 1 7.

In known manner, the two arrangements are arranged in such a way that, or are associated with means not shown such that, when the film has been cut, the end 27 of the second portion 51 of film, which is then between the two arrangements is directed between the two rollers 20, 21 of the downstream arrangement and is taken up by the latter, before being gripped in turn by the guide device 25 which drives it to the next group of products by traversing at again the appropriate path symbolized by the broken line 26.

According to the invention, a full reel 70 is placed in the machine, while the film 5 of the dispensing reel 7 is being unwound, and the free end 52 of the film 53 connected to this full reel is kept on standby , at the entrance of the injection and cutting means. As illustrated, the machine comprises between this full reel 70 and the inlet of the injection means, a second set of guide devices, with rollers 1 1 0, 120, 1 30, 140, which for some 1 1 0, 1 20, are compensating rollers. These are then attached to mobile mechanisms 1 50, 1 60, such as puppets.

According to the invention, the film 53 connected to the full reel is in two parts: a first 54, which constitutes the remaining portion of the film of a reel which has previously been unwound in place of the reel 70, and a second 55 which constitutes the beginning of the film originally placed on the full reel.

The two parts 54, 55 are connected together by a hot weld 56.

The welding 56 is therefore carried out at the end of the film of the reel which was previously in place of the reel 70 and at the start of the film of the reel 70, when the latter is put in place.

To allow welding, means are provided, such as welding bars 28, 29 between which the film runs.

The first part 54 is arranged on a path which incorporates the second set of guide devices, with the rollers 1 1 0, 1 20, 1 30, 1 40.

Consequently, the sealing bars are arranged between the coil 70 and the second set of guide devices, with its rollers 1 1 0, 1 20, 1 30, 1 40.

The free end 52 of the film 53 connected to this full reel 70 is held at the inlet of the injection means 1 7 by drive and holding means, constituted in the example by rollers 30, 31 for holding whose FIG. 2 illustrates a preferred embodiment.

The holding rollers 30, 31 are connected to non-visible drive members, which are arranged so as to be put into operation in order to drive the film 53 in the direction of the injection rollers 1 8, 1 9 so as to allow it to be taken up by these, and to be stopped to keep the film stopped.

In fact, with the configuration of Figure 1 where it is the film of the reel 7 which is driven by the injection rollers 1 8, 1 9, the holding rollers 30, 31 are in the stopped position. In one implementation, the drive members are arranged to be operated when the film 53 must be driven by the injection rollers, so that the film is driven by the holding rollers at the same speed as by the injection rollers. In a variant, the retaining rollers are disengageable relative to the drive members, and are disengaged when the film 53 is driven by the injection rollers, so that, in this configuration, the film circulates freely between the retaining rollers.

The film 5 being unwound from the dispensing reel 7 also passes between sealing bars 32, 33, to allow the reel to be changed when the latter is emptied in turn, and between holding rollers 34, 35 upstream of the injection rollers 1 8, 1 9.

In the same way as the rollers 30, 31, the holding rollers 34, 35 are connected to non-visible drive members, which are arranged so as to be put into operation to drive the film 5 towards the injection rollers 1 8 , 1 9 to allow its recovery by the latter, and to be stopped to keep the film stopped.

With the configuration of Figure 1 where it is the film of the reel 7 which is driven by the injection rollers 1 8, 1 9, the holding rollers 34, 35 are controlled or placed in a position such that the film of the coil 7 flows freely.

This embodiment therefore makes it possible to change the film without emptying one or the other of the guide devices with the compensating rollers.

Thus, for example, if we consider the dispensing reel 7, during actual distribution, it suffices to detect the position of the end of the film 5 on this reel before said end reaches the guide device 1 1, 1 2, 1 3 corresponding, and when it reaches a predetermined position, to manually or automatically stop this coil, to reverse the direction of rotation of the injection rollers, to take up the film 5 with the corresponding holding rollers 34, 35 , and launch the other film 53 towards the injection rollers using the corresponding holding rollers 30, 31.

Of course, as already explained, if after stopping the film 5, it is detected visually or automatically that there is still sufficient usable film, it is always possible to restart this film, manually or automatically, until the film actually reaches the end of the reel, and ensure that it does not leave the corresponding guide device.

Then, the other coil is restarted, and a new coil is put in place before welding.

In Figure 2, there is illustrated a preferred embodiment of the device 1 6 comprising, inter alia, the means 1 7 for injecting and cutting the film.

The device 1 6 is shown in a position that it is the film 53 which is driven, and the film 5 which is stopped.

As already mentioned, the injection and cutting means comprise the upstream arrangement of two injection rollers 1 8, 1 9, and the downstream arrangement of two other pressure rollers 20, 21, as well as, between these two arrangements, the device with a member 22 for cutting the film, consisting of a sharp blade carried by the bar 23 which can rotate around its longitudinal axis.

Two sets of holding rollers are arranged upstream of the injection rollers 18, 19. The film 53 is arranged so as to pass between the rollers 300, 31 0 of the first set, and the film 5 is arranged so as to pass between the rollers 340, 350 of the second set.

One of the rollers 300, 350 of each of these assemblies is not completely cylindrical, but is provided with a flat 301, 351 parallel to the axis of rotation of its respective roller 300, 350. The drive members, not shown, are arranged to arrange the flat face opposite the other roller of the device when the film is to be driven by the injection rollers, so that the film runs freely in the gap which then appears between the two rollers.

Thus, if we consider this Figure 2 where it is the film 53 which is driven, the rollers 300, 31 0 are stopped, with the flat 301 of the roller 300 facing the roller 31 0; the rollers 340, 350 are stopped with their cylindrical part in tangential contact to block the film 5.

When the film is changed, the direction of rotation of the injection rollers 1 8, 1 9 is reversed to release the start, and the holding rollers 300, 31 0 are simultaneously rotated to tighten the film 53 and avoid that it does not disengage from these, then we stop them holding rollers; then the rollers 340, 350 are rotated to drive the free end of the film 5 in the injection rollers.

However, to prevent a film from disengaging from the holding rollers when the latter are rotated to drive the film towards the injection rollers, the gap should not appear during this phase. For this purpose, the holding rollers of each device are arranged in such a way that the length of the portion of film which is likely to be caught between the injection rollers and the holding rollers is less than the perimeter of the cylindrical portion. of each roller provided with a flat.

Figures 3 and 4 illustrate two variants of the device 1 6 in which the injection means consist of two devices in parallel, and in which the maintenance of a film in the stopped position is carried out using the injection rollers of the film in question, and there are provided, at the outlet of the device 1 6, means for directing the film during unwinding towards the mobile guide device 25, constituted for example by the arrangement of bars which come to grip the film at its exit from the downstream arrangement of pressure rollers 20, 21, and subject it to the appropriate path, symbolized by the broken line 26, in the direction of the bundling zone.

In FIG. 3, a first injection and cutting device comprises the injection rollers 1 81, 1 91, the pressure rollers 201, 21 1, and a cutting member 231; a second injection and cutting device comprises the injection rollers 1 82, 1 92, the pressure rolls 202, 21 2, and a cutting member 232; the means for directing the film during unwinding towards the mobile guide device 25 are two belts 36, 37 each located at the outlet of an injection and cutting device to take up the film which leaves therefrom.

A first belt 36 is for example stretched between a pressure roller 201 of the first injection and cutting device and a tension roller 221; the second 37 is for example stretched between a pressure roller 21 2 of the second injection and cutting device and a tension roller 222.

In the example illustrated, it is the film 53 which is entrained in the first injection and cutting device: the film 5 is kept stationary by the rollers 1 82, 1 92 of injection of the second injection and cutting device.

At the outlet of the first injection and cutting device, the film 53 is directed towards the means 25 by the belt 36. In FIG. 4, a first injection and cutting device comprises the injection rollers 1 83, 1 93, the pressure rollers 203, 21 3, and a cutting member 233; a second injection and cutting device comprises the injection rollers 1 84, 194, the pressure rollers 204, 21 4, and a cutting member 234; the means for directing the film during unwinding towards the mobile guide device 25 are a single belt 38, the path of which makes it pass between the pressure rollers of the two injection and cutting devices.

Here, it is the film 53 which is kept stationary by the rollers 1 83, 1 93 of injection of the first injection and cutting device, and the film 5 is guided towards the means 25 by the belt 38 .

Claims

claims

1. Method for recharging a machine for packaging groups of products (1, 2, 3, 4) using a plastic film (5; 51; 53) intended for said packaging, said machine comprising on the one hand means (1 7) for injecting and cutting the film supplied with film from a distributor reel (7), located upstream, in the direction of travel of the film, means (1 7) for injection and cutting, and secondly means for storing a full reel (70), also upstream of the means (1 7) for injection and cutting, the method being of the type according to which, after detection of the approaching the end of the film (51) of the dispensing reel (7), various steps are carried out which make it possible to finish unwinding and emptying it, and to engage the film of the full reel (70) in the injection means (17), so that the latter becomes distributor in turn, then the one (7) which has been emptied is replaced by a new full coil, is characterized in that it consists: while a reel (7) is being dispensed, placing a reel (70), full, in the machine, and keeping it waiting, at the input of the means (1 7 ) injecting and cutting the free end (52) of the start of the film connected to this full reel; after having detected that the end of the film end of the reel (7) during dispensing reaches a predetermined position in the machine, to stop the progression of the film (51) of this reel in the means (1 7) of injecting and cutting, and causing the latter to drive the free end (52) of the film (53) connected to the full reel (70), so that the latter becomes a distributor; while the latter (70) is being dispensed, to replace the one (7) which has been emptied by a new full reel, and to maintain at the inlet means (1 7) for injection and cutting the free end, from the start of the film connected to this new reel, and repeat the above cycle with the new reel, when the end of the film from the reel (70) which is then being dispensed, reaches in turn a predetermined position in the machine.

2. Method according to claim 1, characterized in that the entire film (51) of the reel during distribution is allowed to spin, and the predetermined position, which is detected, from the end end, of the film of this reel, in the machine is where the said end of film leaves the means (1 7) of injection and cutting.

3. Method according to claim 1, characterized in that it consists in monitoring the passage of the end end of the film (51) of the reel (7) during dispensing, in the machine, in a predetermined position located between the coil (7) and the means (17) of injection and cutting, and; when the passage in this position is detected, to stop the progression of the film (51) of this reel in the means (1 7) of injection and cutting, so that there remains a remaining portion of film between said end of end of the film and the means (1 7) of injection and cutting, and to cause the drive, in the latter, of the free end (52) of the film (54, 55) connected to the reel (70) full, so that it becomes a dispenser; remove the empty spool and place a new full spool instead; welding (56) the start of the film (55) from the full reel (70) to the end (54) of the remaining part of the film which has been removed.

4. Method according to claim 3, characterized in that the detection of the predetermined position of the end of the film (51) of the reel (7) during distribution is carried out in two stages: a first where the length is estimated approximately remaining film wound on this reel during the distribution then, when a predetermined value is reached, the progression of the film of this reel is stopped in the injection and cutting means (1 7), the reel is put into service (70) full by causing the drive, in the means (1 7) of injection and cutting, of the free end (52) of the film (53) connected to this full reel, so that it becomes dispenser and the other (7) is stopped and a second time where the remaining length of the film wound on the reel (7) is precisely determined when stopped, following which: a) if the remaining length of film on this reel (7) when stopped is sufficient to continue packing product groups (1, 2, 3, 4): we stop the progression of the film (53) of the other (70), which has become distributor, in the means (1 7) of injection and cutting, we cause the drive, in the latter, of the end free of the film connected to the reel (7) which was on standby, so that the latter becomes distributing again, and the passage of the upstream end, end, of the film (51) of this reel is monitored in the machine, in said predetermined position located between the coil and the means (1 7) of injection and cutting, and; when the passage in this position is reached, the film progression of this reel (7) is again stopped in the means (17) of injection and cutting, the other reel (70) is put back into service, causing the entrainment, in the latter, of the free end of the film connected to this other reel, so that the latter becomes distributing again; remove the empty coil and place a full coil instead; the start of the film from the full reel is welded to the end end of the remaining part of the film from the removed reel, and it is waited until the remaining length of film wound on the second requires a new reel change; b) if the remaining length of film on this reel (7) at standstill is insufficient to continue to pack groups of products (1, 2, 3, 4): we continue to pack with the film of the other reel (70), until it is judged that the remaining length of film wound on it requires a new reel change and, during this time, the end of the film is brought from the first reel , in the machine, in said predetermined position located between the coil and the means (1 7) for injection and cutting, and the empty coil is removed and a full coil is placed instead; the start of the film from the full reel is welded to the end end of the remaining part of the film from the reel which has just been removed and; we repeat the previous operations by passing from one reel to another.

5. Method according to claim 4, characterized in that the approximate evaluation of the length remaining on the reel being dispensed and / or the precise determination of the length remaining on the reel stopped and / or monitoring the passage of the upstream end, end, of the reel film being dispensed in the machine, in said predetermined position, are carried out by the machine operator.

6. Method according to claim 4, characterized in that the approximate evaluation of the length remaining on the reel being dispensed and / or the precise determination of the length remaining on the reel when stopped and / or the monitoring of the passage of the upstream end, end, of the film of the reel being dispensed in the machine, in said predetermined position, are carried out automatically.

7. Method according to claim 4, characterized in that the stopping of a reel during distribution and / or the putting into service of a full reel and / or the putting back into service of a reel are carried out by l machine operator.

8. Method according to claim 4, characterized in that the stopping of a reel during distribution and / or the putting into service of a full reel and / or the putting back into service of a reel are carried out automatically.

9. Method according to one of claims 3 to 8, characterized in that, the machine comprising a compensation mechanism with rollers (1 1, 1 2, 1 1 0, 1 20) compensators between each coil and the means ( 1 7) of injection and cutting, the predetermined position located between the reel and the means (1 7) of injection and cutting is monitored so that the progress of a reel during distribution is stopped when the end of the film carried by this reel is between the reel and the corresponding compensation mechanism.

1 0. Machine for implementing the method according to one of claims 1 to 9, characterized in that it comprises two arrangements for alternately driving the start of the film from one reel and the other in the means ( 17) for injection and cutting, and these arrangements include means (30, 31; 34, 35; 300, 31 0; 340, 350) for driving and holding, arranged to hold means ( 1 7) for injection and cutting the start end of the film from the stand-by reel, and to allow the film from the dispensing reel (7) to be driven into the means (1 7) for injection and cutting .

1 1. Machine according to claim 1 0, characterized in that the arrangements are identical.

1 2. Machine according to one of claims 1 0 or 1 1, characterized in that the means (1 7) of injection and cutting consist of a single injection and cutting device comprising, at its inlet, rollers (1 8, 1 9) for injecting the film, and the means (30, 31; 34, 35; 300, 31 0; 340, 350) for driving and holding consist of two separate devices for drive and holding arranged upstream of the injection rollers, and the machine is arranged so that, after having stopped the progression of the film from a reel being dispensed in the injection and cutting device, the direction is reversed progression of this film in said device, so as to release the start end, and it is maintained with the corresponding drive and holding device, then the end of the film is brought to a standby between the injection rollers with the other corresponding drive device t and holding.

13. Machine according to claim 1 2, characterized in that each of the two drive and holding devices consists of two rollers (30, 31; 34, 35; 300, 31 0; 340, 350) for keeping in contact with each other, between which a film is placed, and these rollers are arranged to either drive the film in the direction of the injection rollers (1 8, 1 9) in order to allow its recovery by the latter, or maintain the film stopped, or let the film unwind when it must be driven by the injection rollers.

14. Machine according to claim 13, characterized in that the holding rollers are connected to motor members, which are arranged so as to be put into operation to drive the film in the direction of the injection rollers to allow its recovery by these, and to be stopped to keep the film stopped.

1 5. Machine according to claim 1 4, characterized in that the drive members are arranged to be operated when the film is to be driven by the injection rollers, so that the film is driven by the rollers maintained at the same speed as by the injection rollers.

1 6. Machine according to claim 14, characterized in that the holding rollers are disengageable relative to the drive members, and are disengaged when the film is driven by the injection rollers, so that, in this configuration, the film circulates freely between the holding rollers.

1 7. Machine according to claim 14, characterized in that at least one of the rollers (300, 350) for holding each drive and holding device is provided at its periphery with a flat (301, 351) , parallel to the axis of rotation of the roller, and the drive members are arranged to arrange the flat (301, 351) facing the other roller (31 0, 340) of the device when the film is to be driven by the rollers injection, so that the film runs freely in the gap which then appears between the two rollers, and the injection rollers and the holding rollers of each device are arranged so that the length of the film portion which is likely to be caught between the injection rollers and the holding rollers, when the flat part of a roller is not opposite the other roller of the same device, is less than the perimeter of the cylindrical portion of each roll with a flat .

1 8. Machine according to one of claims 1 0 or 1 1, characterized in that the means (1 7) of injection and cutting consist of two separate injection and cutting devices which each receive the film ( 5, 53) of a coil, and each comprise, at their entry, rollers (1 82, 1 92; 1 81, 1 91 (fig. 3); 1 83, 1 93; 1 84, 1 94 (fig .4)) film drive, and the drive and holding means are constituted by the rollers (1 82, 1 92; 181, 1 91 (fig. 3); 1 83, 1 93; 1 84, 1 94 (fig. 4)) drive, located at the entrance of the injection and cutting devices, and the machine is arranged so that, the progression of the film from a reel being dispensed into a device injection and cutting is stopped by stopping the rotation of its input drive rollers, and the driving of the start end of the film waiting in the other injection and cutting device is caused by putting in rotation its input drive rollers.

1 9. Machine according to claim 1 8, characterized in that it comprises means (36, 37, 38) to accompany the film being distribution leaving one or the other of the two separate injection and cutting devices in the direction of a zone (8) of the machine where the packaging of the groups of products is carried out (1, 2, 3, 4 ).

20. Machine according to claim 1 9, characterized in that the means (36, 37, 38) for accompanying the film being dispensed comprise at least one conveyor belt which is arranged, in the direction of progression of the film, in downstream of the organs (231, 232, 233, 234) for cutting each of the separate injection and cutting devices.

21. Machine according to claim 20 characterized in that a belt is arranged so as to accompany the film up to the packaging area.

22. Machine according to claim 20 characterized in that a belt is arranged so as to accompany the film up to a mobile guide device (25), for gripping the film at its exit from the belt and making it undergo a path (26) suitable for surrounding the group of products.