EP0000851B1 - Automatic machine for cutting a thermoplastic tube in parts and for applying sleeves around containers - Google Patents

Description

The present invention relates to the field of making sheath sections of heat-shrinkable plastic and intended to be placed and then shrunk hot around containers. It relates more particularly to a new apparatus allowing the production in contunu, at high rate, of such sections or sleeves from a continuous strip of flat sheath as well as the conformation of these sleeves to the types of containers to be coated and then their automatic laying around of these containers.

It is now well known to provide containers such as bottles, aerosol cans, bottles, cans and the like, made of various materials, with a protective sleeve or sheath made of shrinkable plastic. This sleeve is placed relatively loosely around the container and, after heating to cause the plastic to shrink, it must conform perfectly to the outline of the container. Receptacles are thus produced provided with sheaths, generally printed, in transparent thermoplastic material or in porous or cellular plastic material.

Many operating steps are necessary to pass from the thin plastic sheet (for example polyvinyl chloride), made heat shrinkable, to the receptacle provided with its decorated covering. These steps must be automated to achieve adequate industrial profitability. According to the technique most commonly used so far, the plastic film is made of a sheath or continuous sheath and then sections of sheath are cut to the appropriate demensions and the sleeves obtained, stacked horizontally or vertically in a store, are used to feed a machine allowing individually extract the sleeves then open them to the desired shape and place them around the receptacles to be coated which circulate on a conveyor, the covering then being subjected to heat shrinkage (see for example French patent No. 2,355,719 of February 1976 and its certificates of addition No. 2,369,971, 2,376,794 and 2,395,897).

This process is certainly satisfactory, but the apparatus for implementing the sleeves is of a fairly delicate adjustment, which affects its reliability. On the other hand, the production rates are relatively limited due to the complexity of the sleeve opening operations. Finally, the presence of the two fold lines of the sleeves deposited on the containers sometimes creates difficulties during the final heat-shrinking operation.

The invention aims to remedy these various drawbacks and aims to produce and install, at high speed, sleeves already having the general shape of the containers to be coated. It offers, for this purpose, an automatic apparatus which directly uses as raw material the continuous flat sheath of plastic film and not stacks of sheath sections and which performs the series of operations of: shaping, cutting, guiding and laying the sleeve, along a vertical line overhanging the series of receptacles which run on a conveyor.

It has already been recommended, of course, apparatus for fitting thermoplastic sleeves around containers from a tubular sheath, these apparatuses comprising a supply in flat sheath and a vertical assembly for cutting the sheath into sections which are then opened and guided on a vertical mandrel aligned with the containers to be coated before expulsion downwards just above each container (see for example American patent N ° 4,016,704). However, the implementation of the corresponding method gives rise to difficulties, in particular in the coordination of the various phases, owing to the fact that the non-unfolded sheath sections are cut and opened before introduction onto the mandrel.

The invention makes it possible to obviate these drawbacks and to solve the problem of opening the sheath and then cutting into sections and driving them before expulsion over the containers to be coated, on the same vertical chuck with automatic adjustments and programmed phase rates.

The improved machine is of the general type described above, but it is essentially characterized in that: a / it comprises means for removing the two folds of the flat sheath, before cutting of the latter, b) the cutting means are arranged around the mandrel and not above it; and c) it contains, under the cutting means, stepped means allowing automatic adjustment of the heights and cutting rates.

In this machine, the supply of flat sheath to the vertical assembly is done by means of a closed package containing one or more sheath coils and provided with a horizontal slot allowing passage to the continuous strip. This strip, first subjected to a strong traction is then released to allow the subsequent adjustment of a predetermined cutting length, then it is again stretched over said verticle assembly.

According to one characteristic, all of the operations performed on the sheath are carried out around a hollow carrier mandrel whose cross section corresponds to the configuration desired for the final sleeve. This mandrel is carried by horizontal platforms delimiting several stages and provided with retractable lugs intended to engage in grooves provided on the mandrel.

According to an alternative embodiment, the thermoplastic flat sheath is subjected to a precut operation before being engaged around the tapered upper part of the hollow mandrel. This operation, which can be carried out for example by means of a sawtooth blade penetrating into a counterpart made of rubber, makes it possible later to obtain a sharper and faster cut.

The means of unfolding the sheath, just after the engagement of the latter around the mandrel, are constituted by jaws heated by any known means (electric, hot air, infrared, etc.) and whose contact time with the sheath on the mandrel is programmed in sequence with the cut and according to the temperature (generally between 70 and 120 ° C). These jaws can be controlled by any known means with an alternative function.

The means for cutting the sheath into sections or sleeves can advantageously be constituted by a rotary device provided with horizontal blades, for example two which penetrate into the sheath when they are already in rotation. However, other equivalent cutting systems, such as cutting jaw device, cutting ring or the like, can of course be implemented. According to an alternative embodiment, it is also possible to provide, associated with the straight cut system of the sheath, a microperforation device intended to create a pre-cut line for obtaining sleeves of special type.

The steps which follow the cutting means are preferably three in number and essentially have the function of ensuring the lift and the centering of the mandrel during the cutting of the sheath then the descent and expulsion of the sleeves. The actions of these different levels are carried out in sequence, in particular by means of a central camshaft, in such a way that there are always, during the running of the machine, two open levels (i.e. clear of the mandrel) and a closed level (platform blocking the mandrel) or vice versa.

The means for guiding the sheath on the mandrel are constituted on the one hand by rollers or rollers with alternative control and on the other hand by lug chains controlled by the camshaft. In addition, according to an important characteristic of the invention, the descent of the cut section of sheath and then its expulsion at the bottom of the mandrel are facilitated by sending, within this hollow mandrel and provided with microperforations preferably oriented downward, air or any other slightly pressurized fluid. This injection of fluid is triggered automatically after the cutting operation and is advantageously carried out at two points on the hollow mandrel, under different pressures.

All of the machine's components are placed on a frame provided with a series of disc-type clutch-brakes (or equivalent) driven alternately by chain pulleys or the like and which are actuated by a single motor or motor-variator. . According to a characteristic of the invention, this frame can support several cutting assemblies, for example two, three or more. Thus, as will be seen below in more detail, the removal of the sleeves around the containers can be done continuously and at high speed during the movement of the containers on their conveyor.

• Fig. 1: une vue générale de face des principaux organes d'une machine selon l'invention;
• Fig. 2: une vue de l'arrière de cette machine;
• Fig. 3: un ensemble comprenant une machine de pose de l'invention, associée à un convoyeur en continu de récipients et à un dispositif de rétraction à chaud des manchons après leur pose autour des récipients;
• Fig. 4: un mode de mise en tension et relâchement de la gaine thermoplastique servant à l'alimenter l'ensemble verticale de découpe, transfert et pose des manchons ou tronçons de gaine;
• Fig. 5: un mode de maintien du mandrin , central par la plate-forme de l'un des étages de l'ensemble vertical;
• Fig. 6: un mode d'entraînement par chaîne d'un manchon le long du mandrin central de chaque ensemble vertical;
• Fig. 7: une vue de côté simplifiée, d'un ensemble vertical illustrant de façon schématique les principaux éléments d'un ensemble vertical.

Other characteristics will become apparent during the following description, relating to a nonlimiting embodiment, illustrated by the appended schematic drawings which represent:

• Fig. 1: a general front view of the main members of a machine according to the invention;
• Fig. 2: a view of the rear of this machine;
• Fig. 3: an assembly comprising a laying machine of the invention, associated with a continuous conveyor of containers and with a device for hot shrinking of the sleeves after their laying around the containers;
• Fig. 4: a method of tensioning and loosening the thermoplastic sheath used to supply it with the vertical cutting, transfer and fitting assembly of sleeves or sections of sheath;
• Fig. 5: a mode for holding the mandrel, central by the platform of one of the stages of the vertical assembly;
• Fig. 6: a chain drive mode of a sleeve along the central mandrel of each vertical assembly;
• Fig. 7: a simplified side view of a vertical assembly schematically illustrating the main elements of a vertical assembly.

As shown in FIGS. 1 and 2, the machine essentially comprises: a magazine 1 for supplying a flat sheath of thermoplastic film; a system 2 for winding and distributing this sheath; one or more vertical assemblies 3 (the machine shown contains three) intended for cutting the sheath then for guiding and laying the sheath sections around containers; finally a series of means for transmitting the movements of the various members as well as means for controlling the movements of transfer and opening-closing of the stages of each vertical assembly. As will be described in more detail below, the machine is installed above a conveyor 4 intended for the continuous feeding of the receptacles to be coated and provided with a device 5 for hot shrinking of the sleeves after their removal around each receptacle.

The magazine 1 is advantageously constituted by a rectangular box, for example of cardboard, where one has arranged vertically side by side, separated by spacers, for example two coils 6 of plastic sheath wound at flat as obtained by continuous welding of two close edges of a heat-shrinkable plastic film such as for example polyvinyl chloride. The sheath can, of course, be provided with any prints and decorations according to known methods. One coil is kept in reserve while the other is used to power the machine. The packaging is provided with a slot 7 and the sheath 8 follows, as can be seen in FIG. 4, a path along which it is subjected to different tensions. At the start, the flat sheath is strongly pulled in tension by the cylinders 9 and then it is released by means of a flexible interlocking system 10 passing in front of a photoelectric cell 11; a sheath reserve is thus created during the subsequent cutting operation and the cell makes it possible to re-tension the sheath in order to deliver a new length of section to the assembly 3. The drive of the continuous strip up to the top of the assembly 3 takes place between series of rollers or rollers 12 driven by the motor 13. As will be seen later, this single motor controls the series of clutch-brakes provided for the operation of the moving parts of the machine, as well as the camshaft for controlling the elements of each vertical assembly.

When the thermoplastic sheath 8 passes over the upper part of the assemblies 3, it can be subjected, if desired, to a pre-cutting operation before being engaged around the tapered head of the hollow mandrel 14. This operation, which can be practiced for example, using a sawtooth blade penetrating into a rubber counterpart, makes it possible to subsequently obtain a clearer and faster cut of the sheath into sections.

After its engagement, at the start of unwinding of the coil 6 around the head of the mandrel, the sheath 8 is subjected to operations of: unfolding, cutting, transfer and fitting of the sleeves around the receptacles to be dressed, all these operations being carried out in synchronism, as will be seen below, in each of the vertical assemblies generally designated by the number 3.

• -des mâchoires chauffantes 15 de déplissage de la gaine après l'enfilage de celle-ci sur l'extrémité supérieure du mandrin 14;
• -des galets de guidage 16 de la gaine;
• - des disques 17 de dégagement de coupe en prise avec un dispositif de coupe 18, ces disques 17 engrenant sur les pignons 19 d'un arbre à came 20;
• -des galets 21 puis des chaînes 22 d'accompagnement vers le bas du tronçon de gaine déjà coupé;
• -une première plate-forme 23 au niveau de laquelle on envoie au sein du mandrin 14 de l'air sous faible pression (canalisation 24) destiné à accompagner le transfert vers le bas du manchon sur coussin d'air;
• - une deuxième plateforme 25 correspondant à l'envoi, par la canalisation 26, d'air sous pression plus forte pour assurer l'expulsion du manchon sur le récipient à recouvrir (flèche 27);
• -une troisième plate-forme 28; proche de l'extrémité inférieure du mandrin 14, qui se termine avantageusement par une coiffe tronconique 29 permettant de réaliser un parfait alignement du récipient sous le mandrin.
• -l'ensemble de transfert et les mouvements d'ouverture-fermeture des trois étages qui correspondent aux plate-formes (23,25,28) étant commandés par l'arbre à came 20 entrainé par le moteur 13 et dont les ensembles de pignons (19,29,30,31 ) sont en prise avec les divers organes précités qui travaillent autour du mandrin creux 14.

Each vertical assembly essentially comprises, arranged around the vertical hollow mandrel 14, a series of means formed from top to bottom by (see FIGS. 1 and 7):

• -heating jaws 15 for unfolding the sheath after the threading thereof on the upper end of the mandrel 14;
• -guide rollers 16 of the sheath;
• - Cutting clearance discs 17 engaged with a cutting device 18, these discs 17 meshing on the pinions 19 of a camshaft 20;
• rollers 21 then chains 22 accompanying down the sheath section already cut;
• -a first platform 23 at which is sent within the mandrel 14 air under low pressure (pipe 24) intended to accompany the downward transfer of the sleeve on the air cushion;
• - A second platform 25 corresponding to the sending, via the pipe 26, of air under higher pressure to ensure the expulsion of the sleeve on the container to be covered (arrow 27);
• a third platform 28; near the lower end of the mandrel 14, which advantageously ends in a frustoconical cap 29 allowing perfect alignment of the container under the mandrel.
• -the transfer assembly and the opening-closing movements of the three stages which correspond to the platforms (23,25,28) being controlled by the camshaft 20 driven by the motor 13 and whose pinion assemblies (19,29,30,31) are engaged with the various aforementioned members which work around the hollow mandrel 14.

Of course, the series of power cables and the accessory members have not been shown in the figures of the appended plates so as to improve clarity and facilitate understanding.

We will now resume below a more detailed description of certain essential members of a vertical assembly of the machine.

The mandrel 14 which can have any shape, for example cylindrical, is constituted by a hollow element, made of plastic, metal or alloy, the wall of which is provided with microperforations intended to let escape a flow of air or other blown fluid inside. This mandrel 14 is permanently maintained and adjusted in the vertical position by at least one of the platforms 23,25,28. For example, as can be seen in FIG. 5, a platform (example: 23) is provided with several lugs 32, actuated by springs 33 or other means, these lugs coming to be housed in a groove or groove 34 provided on the periphery of the mandrel 14. According to a variant, not shown in the figures, the mandrel can be held at least at one of the platforms 23,25,28 by a jaw adapting to an appropriate housing of the mandrel.

While the sheath is driven in its descent on the mandrel 14 by the rollers 16 actuated by the clutch-brake 35 connected to the camshaft, this sheath is subjected to unfolding by means of the heating jaws 15 formed, for example , by two metal half-shells internally coated with a plastic material (silicone rubber or the like) intended to avoid any possible local overheating. Thanks to their constitution, these two shells join together on the mandrel 14.

After unfolding, the sheath is subjected to cutting 18 for example using a rotary device with blades, designated by the number 18 on the Figures 1 and 7, which is also driven by the motor 13 and the blades of which penetrate the film when they are already in rotation. According to a particular embodiment, one can add to this cutting device a microperforation system intended to create in a given area of the sheath an additional pre-cut line.

At the level of the cut and preferably just below or just above depending on whether the sheath is printed or not, a photoelectric cell (not shown in the figures) is installed which makes it possible to determine the appropriate length of each section of sheath.

As said above, the opening and closing functions of each of the stages delimited by the platforms (23,25,28) along the mandrel 14 are controlled by the various pinions of the camshaft 20. The downward transfer and expulsion of the sleeve (arrow 27) are facilitated by the pressurized air sent under two different pressure flows by pipes 24 and 26. The third pipe 38 visible in Figure 1, is connected to the cylinder (not shown) which is used to power the possible precut device which can be installed above an assembly 3.

According to a characteristic of the invention, a chain 22 is provided on each side of the mandrel 14 provided with a lug or projecting finger 36 (see FIG. 6) and which, controlled by the camshaft 20, accompanies the progression of the sleeve 37 downwards, the movement of this chain being synchronized with the opening and closing operations of the stages.

The brief description of an embodiment of a machine as defined above will allow a better understanding of the invention.

When the sheath 8, possibly pre-cut, has just been threaded onto the mandrel 14 (start of bonine), the mandrel is held in position by closing the lugs 32 provided on the platform 28 of the lower stage ( rest position). The platforms 23 and 25 are open while the platform 28 is closed; the roller systems 16 are set in motion to lower the sheath over the length of cut to be made. The electromagnet cell (not shown) causes these rollers to stop and controls the unfolding operation at 15 then triggers the cut at 18. The end of cut, detected by counterfeiter, triggers the rotation of the rollers 21, camshaft 20 and chains 22 accompanying the sheath section. The camshaft rotates, closes the stage 23 and opens the stage 25. During this time, the chain 22 ensures the passage of the sheath section to the stage 25. The camshaft 20 continues to rotate then it ensures the closing of the stage 25 and the opening of the stage 28. The sheath section then continues its course until the lug chain 22 has exploded, with the support of the air pressure sent through the pipe 26, the sleeve outside the hollow mandrel 14. At this time, the lower stage 28 closes while the upper stage 23 opens and the cycle begins again in the order indicated above.

Thanks to a machine with three heads (or vertical assemblies mentioned above), as illustrated in FIGS. 1, 2 and 3, it is possible to obtain a laying rate of approximately 120 sleeves per minute around receptacles to be coated.

In practice, as illustrated in FIG. 3, the machine is installed above a conveyor 4 intended for the continuous feeding of the containers to be sleeved. One can use for example for this purpose the conveyor described in the French patent N ° 2 328 614 of October 9, 1975 (and Certificates of Addition N 2 332 909, 2 345 348 and 2 376 028. Such a belt conveyor without end is provided with a heating tunnel 5 intended to heat-shrink the sleeves around the containers brought by the conveyor and covered by a vertical assembly 3.

Of course, all other bodies with equivalent function can be substituted for those described in the above non-limiting example without departing from the scope of the present invention.

Claims (7)

1. Machine for cutting automatically at programmed rates heat-shrinkable plastic sheath into lengths or sleeves suitable for being disposed and then heat shrunk around receptacles, of the type comprising, arranged on a frame: means (1) for supplying plastic sheath in flattened form and then for conveying (2) the continuous strip under predetermined conditions of tension; a vertical assembly (3) for cutting the sheath into lengths, which is provided with: means (18) for cutting the sheath, means allowing a perforated hollow mandrel (14) to be kept in a vertical position and means (16, 21, 22, 26) for guiding and ejecting sleeves towards the bottom of the mandrel, these sleeves being then disposed around the receptacles to be covered travelling on a conveyor and then subjected to a heat shrinking, the said machine being characterised in that:

a) it includes means (15) for removing the two folds in the flat sheath, before cutting of the latter;

b) the said cutting means (18) are disposed around the mandrel and not above the latter;

c) it contains, under the cutting means (18) means in stages (23, 25, 28) allowing automatic adjustment of cutting heights and rates.

2. Machine according to claim 1, characterised in that the means for removing the folds in the sheath are constituted by heating jaws (15) whose time of application to the mandrel (14) on which the sheath (8) has been fitted is programmed in sequence with cutting of the sheath and is a function of the heating temperature of the said jaws.

3. Machine according to claim 1, characterised in that the means for cutting the sheath are constituted by a rotary apparatus (18) with one or several plates which engage on the sheath (8) while they are already in rotation around the mandrel (14).

4. Machine according to claim 1, characterised in that the said means in stages comprise platforms (23, 25, 28) concentric with the mandrel and provided with retractable catches (32) intended to fit in grooves (34) provided on the mandrel (14), these platforms delimiting at least two stages (23-25 and 25-28) for adjusting the cutting height, transfer towards the base of the sleeve and its ejection at the bottom of the mandrel.

5. Machine according to any one of claims 1 to 4 characteised in that the means (15) for removing folds in the sheath, the cutting means (18) and the means (16, 21, 22, 26) for guiding-transferring-ejecting the lengths of sheath are controlled by a central cam shaft (20) connected to the series of gears (19, 29, 30, 31), this shaft ensuring synchronization between successive openings and closings of the stages of the said vertical assembly.

6. Machine according to claim 1, characterised in that the continuous flat sheath (8) is subjected to a pre-cutting operation before its introduction about the mandrel of a vertical assembly.

7. Machine according to claim 1, characterised in that the lower end of the hollow mandrel (14) is provided with a cap (29) substantially frustro-conical in shape allowing the mandrel (14) to be perfectly aligned with the receptable to be covered with the sleeve.

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