EP0096635B1 - Method and device for regulating the pre-stretching of a plastic film, especifically in view of the packaging of a load - Google Patents

Method and device for regulating the pre-stretching of a plastic film, especifically in view of the packaging of a load Download PDF

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Publication number
EP0096635B1
EP0096635B1 EP19830401119 EP83401119A EP0096635B1 EP 0096635 B1 EP0096635 B1 EP 0096635B1 EP 19830401119 EP19830401119 EP 19830401119 EP 83401119 A EP83401119 A EP 83401119A EP 0096635 B1 EP0096635 B1 EP 0096635B1
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EP
European Patent Office
Prior art keywords
film
tension
load
stretching
prestretching
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19830401119
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German (de)
French (fr)
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EP0096635A3 (en
EP0096635A2 (en
Inventor
André Jean Bouvier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Procter and Gamble European Technical Center
Procter and Gamble Co
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Procter and Gamble European Technical Center
Procter and Gamble Co
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Publication of EP0096635A2 publication Critical patent/EP0096635A2/en
Publication of EP0096635A3 publication Critical patent/EP0096635A3/en
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Expired legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
    • B65B11/00—Wrapping, e.g. partially or wholly enclosing, articles or quantities of material, in strips, sheets or blanks, of flexible material
    • B65B11/04—Wrapping, e.g. partially or wholly enclosing, articles or quantities of material, in strips, sheets or blanks, of flexible material the articles being rotated
    • B65B11/045—Wrapping, e.g. partially or wholly enclosing, articles or quantities of material, in strips, sheets or blanks, of flexible material the articles being rotated by rotating platforms supporting the articles

Definitions

  • the invention relates to a method and a device for regulating the pre-stretching of a film of stretchable plastic, in particular for the packaging of a load.
  • a device for packaging loads is described by means of a film of stretchable plastic, which comprises first and second successive pairs of stretching rolls between which the film passes, the downstream cylinders of the second pair rotating at a peripheral speed higher than that of the upstream cylinders of the first pair, the free end of the stretched film being driven by suitable means placed downstream of the second pair of cylinders, at a lower speed or equal to the peripheral speed of the cylinders of this second pair.
  • DE-A-2 750 780 describes the control of the speed of a reel from which a film is unwound, by means of an electromagnetic braking system.
  • the reel speed varies according to a “film tension measurement, but this measurement is in fact the variation of the angle of arrival of the film at the station of use and depends on the (angular) shape of the load to be packed.
  • the object of the invention is to remedy this operating deficiency in the above-mentioned elongation range by continuously adapting the degree of pre-stretching of the plastic film to the tension generated in this film by the wrapping of the load. to be packaged, so that the sum of the elongation produced by the pre-stretching and the additional elongation produced by the tension created in the film before it reaches the load to be packaged does not exceed the breaking elongation.
  • the speed of the last pre-stretching cylinder is varied.
  • the method is used for packaging a load.
  • the method and the device according to the invention are applicable in particular to the packaging of loads, in particular palletized loads consisting of a certain number of elementary packages. It should also be noted that the invention is applicable both when the packaging is carried out by progressive winding of the film around the load and in the case where it is operated by the so-called “curtain” method, that is to say ie where the charge is pushed against the plastic film so as to be wrapped as a whole.
  • fig. represents a machine operating by progressive wrapping of a load P which is placed on a turntable T.
  • This load can be formed of several unitary packages which are held in place on a pallet in the form of an assembly which must be wrapped d 'a plastic film.
  • This film designated by FP in fig.
  • pre-stretching means such as C, and C 2 , which are constituted in the example represented by coated rolls of a substance, rubberized or otherwise, exerting a great friction force on the plastic film.
  • the film thus undergoes a first pre-stretching on the cylinder C, and a second pre-stretching on the cylinder C 2 which rotates at a speed greater than Ci.
  • the film then reaches the load P directly to ensure his wrap.
  • a structure corresponds to what is called a progressive wrapping machine, which gradually wraps the film FP around the load P, the rotary table being able to execute a vertical translational movement.
  • FIG. 3 There is also another structure of a packaging machine, to which the invention can be applied and which is highlighted in FIG. 3.
  • a wrapping machine of the curtain wrapping type according to which the load P is wrapped by being pushed in the direction F against the film FP1, FP2 unwound simultaneously from two reels B1, B2.
  • the two parts of film unwound from the reels B1, B2 are welded before the start of the load transfer movement in the direction F so as to form in front of this load what is called a "curtain" .
  • the two film strands FP1, FP2 are brought together using a device, not shown, so as to completely envelop the load and the two strands FP1, FP2 are welded together behind the load to complete its packaging.
  • a machine of this kind also provides a pre-stretching of the two strands FP1, FP2 of the plastic film using stretching means. suitable and known, which have been materialized in FIG. 3 by the two pairs of cylinders C ,, C 2 and C ' i , C' z . In the known machine, the film strands FP1 and FP2 then arrive directly on the load to be packaged.
  • the plastics used to form a packaging film can undergo a stretching of 400% until breaking while having, after exceeding the limit elastic which roughly corresponds to an elongation of 40 to 50%, a significant improvement in their properties, in particular the tensile strength.
  • the pre-stretching of a plastic film before it arrives on the load to be packaged is therefore extremely advantageous because not only does it improve the properties of the film but also makes significant savings in materials since It is possible, by lengthening it considerably in the range indicated above, to pack many more products with the same initial length of film. However, if the pre-stretch is pushed too far, approaching the 400% limit excessively, there is a risk of a film rupture.
  • the loads to be packaged often consist of sets of unitary packages of parallelepipedic or cubic shape and there occurs, during the rotational or translational movement of the load to be packaged, a variation in the tension generated in the film of material.
  • plastic This has been highlighted in fig. 1, which is a graphic representation giving the tension in the plastic film as a function of the angle a of rotation of the load.
  • fig. 1 is a graphic representation giving the tension in the plastic film as a function of the angle a of rotation of the load.
  • a sinusoidal curve varying between a maximum and a minimum and which represents the tension in the plastic film during the passage of the point S in the different positions designated by S1, S2 , S3, S4 and S5 in fig. 1.
  • the aim of the method and the device according to the invention is to remedy the shortcomings of known embodiments by simultaneously taking into account the degree of pre-stretching of the plastic film and the tension generated in it when it arrives on the load. to pack.
  • the method according to the invention for regulating the degree of pre-stretching of a film of stretchable plastic material which passes, during the packaging of a load, on one or more means pre-stretching before reaching the load said method consisting in continuously sensing the tension in the part of the film included, considering the direction of movement of the film, between the last pre-stretching means and the load to be packaged , and to vary, in correspondence to the sensed tension, the speed of at least one of said pre-stretching means and / or of the load, so that the sum of the elongation produced by the pre-stretching and of the The additional elongation produced by the tension created in the film before it reaches the load to be packaged does not exceed the elongation at break.
  • the method consists in continuously sensing the tension in the film in the area between the last pre-stretching cylinder. -drawing and the load to react on the speed of this last pre-stretching cylinder in correspondence with the sensed tension.
  • the method according to the invention makes it possible to continuously adapt the operating conditions of the machine to the parameters governing the packaging of a determined load, in particular the shape of this load, its fragility in the corners, its speed of entrainment, nature and strength of the plastic film, etc.
  • the method according to the invention is absolutely not limited to the field of packaging and that it is possible to envisage its application in all cases where it is advantageous, for reasons of improvement of the properties of resistance of the film and of profitability, of ensuring its pre-stretching before its implementation.
  • FIGS 2 and 3 highlight the implementation of the method according to the invention in the two types of packaging machines which have been defined above.
  • FIG. 2 corresponds to the progressive wrapping packaging machine. After the pre-stretching of the film by the cylinders C1, C2, it is necessary to measure the tension of this film in the strand between the point S and the point of tangency to the cylinder C2 so as to be able to react on the pre conditions stretching the film to prevent it from breaking while making the most of the stretching range available.
  • the regulating device further comprises a servo control SC which is connected to the tension sensor so as to permanently receive signals representing the film tension; furthermore the servo-control SC is connected by conductors L1, L2, L3 respectively to the motor M1 for actuating the stretching cylinder C1, to the motor M2 for actuating the stretching cylinder C2 and to the motor M3 for driving the rotary table T on which the load P is placed.
  • a servo control SC which is connected to the tension sensor so as to permanently receive signals representing the film tension
  • the servo-control SC is connected by conductors L1, L2, L3 respectively to the motor M1 for actuating the stretching cylinder C1, to the motor M2 for actuating the stretching cylinder C2 and to the motor M3 for driving the rotary table T on which the load P is placed.
  • It also includes means for instantaneously analyzing the real tension and pre-stretching conditions of the film to modify in correspondence, as indicated by the links L1, L2, L3, the speed of a or more of the motors M1, M2, M3 so that the sum of the elongation caused by the pre-stretching and the elongation caused by the tension in the final film strand remains less than the admissible limit.
  • the LC servo-control reacts, as a function of the signal supplied by the film tension sensor, on the last pre-stretching cylinder C2 before the load in order to thus modify the degree pre-stretching of the film.
  • a hydraulic motor M2 it is advantageous to ensure the control of the last pre-stretching cylinder C2 by a hydraulic motor M2 and there is then provided in the servo-control SC a servo-valve which thus ensures very precise control. of this M2 hydraulic motor.
  • FIG. 3 which corresponds to the mode of wrapping a load "curtain"
  • the application of the method according to the invention is similar to what has been shown in FIG. 2; thus, for each of the film strands FP1 and FP2, a loop-forming mechanism has been provided which has been shown in a simplified form, that is to say a return roller R i , R ′ is simply provided, having the function of forming the tension sensing loop between the last corresponding pre-stretching cylinder C2, C'2 and the point S1, S2 of arrival of the corresponding film strand SP1, SP2 on the load P.
  • the corresponding roller R3, R'3 is mounted on a support SP1, SP'1 which can execute a rectilinear or circular movement; next to the corresponding return roller R3, R'3 there is a sensor CT ,, CT 2 , which has the function of measuring the tension in the associated film strand FP1, FP2 by analysis of the rectilinear or circular displacement of the corresponding roller R3, R'3.
  • the signals from the two sensors CT I , CT 2 are applied to a servo control SC which analyzes them and which reacts accordingly on one or more of the motors M1, M2, M'1, M'2 for driving the pre cylinders. -drawing C1, C2, C'1. C'2 and / or on the motor M3 ensuring the translation of the load P.
  • the deflection roller R 2 placed immediately before the load P is intended to modify the angle of arrival of the film strand FP on the load in order to adapt this angle to the packaging conditions of the charge ; in fact, when the load is fragile, for example when it is formed from thin cardboard packets whose corners can be crushed, it is recommended to reduce this angle to the minimum while in other applications such a parameter may have less important.
  • the method and the device according to the invention are applicable to the particular field of packaging, in particular of charges formed of unitary packages and placed on pallets, but also more generally in all cases. where it is necessary to control the degree of pre-stretching of a plastic film in order to make the most of these strength properties and also to obtain maximum production profitability.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Basic Packing Technique (AREA)

Description

L'invention concerne un procédé et un dispositif de régulation du pré-étirage d'un film de matière plastique étirable, en particulier en vue de l'emballage d'une charge.The invention relates to a method and a device for regulating the pre-stretching of a film of stretchable plastic, in particular for the packaging of a load.

On connaît déjà des procédés et dispositifs permettant d'envelopper une charge avec un film de matière plastique étirable en soumettant le film, avant son arrivée sur la charge, à un pré-étirage permettant d'effectuer l'emballage de la charge en n'appliquant à celle-ci qu'une force bien inférieure à celle qui aurait été autrement nécessaire pour assurer en même temps l'étirage du film. Ainsi, dans le document FR-A-2 281 275, on décrit un dispositif d'emballage de charges au moyen d'un film de matière plastique étirable, qui comprend des première et seconde paires successives de cylindres étireurs entre lesquels passe le film, les cylindres aval de la seconde paire tounant à une vitesse périphérique supérieure à celle des cylindres amont de la première paire, l'extrémité libre du film étiré étant entraînée par des moyens appropriés placés en aval de la seconde paire de cylindres, à une vitesse inférieure ou égale à la vitesse périphérique des cylindres de cette seconde paire.Methods and devices are already known which make it possible to wrap a load with a film of stretchable plastic material by subjecting the film, before it arrives on the load, to a pre-stretching making it possible to pack the load in n ' applying to it only a force much lower than that which would have been otherwise necessary to ensure at the same time stretching of the film. Thus, in document FR-A-2 281 275, a device for packaging loads is described by means of a film of stretchable plastic, which comprises first and second successive pairs of stretching rolls between which the film passes, the downstream cylinders of the second pair rotating at a peripheral speed higher than that of the upstream cylinders of the first pair, the free end of the stretched film being driven by suitable means placed downstream of the second pair of cylinders, at a lower speed or equal to the peripheral speed of the cylinders of this second pair.

Or la plupart des films de matières plastiques utilisés pour l'emballage de charges ont leurs propriétés de résistance améliorées lorsqu'ils sont soumis à un étirage. Ainsi dans le cas particulier du polyéthylène faible densité, il se produit, après dépassement de la limite élastique qui correspond à un allongement d'environ 40 %, une augmentation progressive de la résistance à la traction à mesure que l'allongement croît, la rupture du film se produisant pour un allongement d'environ 400 %. On se rend compte par conséquent qu'il est extrêmement intéressant d'exploiter au maximum la capacité d'étirage d'un film en matière plastique ; non seulement l'emballage acquiert de meilleures propriétés de résistance, mais encore on réalise une économie de matière d'emballage qui croît à mesure que le degré d'étirage augmente.However, most of the plastic films used for the packaging of fillers have their improved strength properties when subjected to stretching. Thus in the particular case of low density polyethylene, there occurs, after exceeding the elastic limit which corresponds to an elongation of approximately 40%, a progressive increase in the tensile strength as the elongation increases, the rupture of the film occurring for an elongation of about 400%. We therefore realize that it is extremely interesting to make the most of the stretching capacity of a plastic film; not only does the packaging acquire better resistance properties, but also a saving in packaging material which increases as the degree of stretching increases.

Dans les réalisations connues, on a cherché à exploiter cette propriété des films de matières plastiques lors de leur pré-étirage avant l'emballage de la charge. Ainsi, dans FR-A-2 470 056 et FR-A- 2 468 506 ou GB-A-2 059 906 on décrit des procédés et appareils permettant d'obtenir un pré-étirage de 300 % à l'aide d'ensembles de rouleaux étireurs.In known embodiments, attempts have been made to exploit this property of plastic films during their pre-stretching before the packaging of the load. Thus, in FR-A-2 470 056 and FR-A- 2 468 506 or GB-A-2 059 906, methods and apparatuses are described making it possible to obtain a pre-stretch of 300% using sets of stretching rollers.

Cependant les machines connues d'emballage équipées d'un dispositif de pré-étirage présentent l'inconvénient de ne pas permettre une exploitation parfaite de la plage d'étirage intéressante comprise entre 50 et 400 %. En effet les dispositifs de pré-étirage sont réglés en début de programme de façon à obtenir un certain degré d'étirage qui tient compte de la matière du film, du profil de la charge à emballer, du risque d'écrasement des coins, notamment dans le cas de paquets en carton fragiles et d'autres paramètres. On est par conséquent amené à prendre initialement des mesures de précaution pour qu'il ne se produise pas de rupture du film de matière plastique en cours de marche de la machine, ces mesures se traduisant en réalité par une forte réduction de la limite supérieure de la plage précitée.However, known packaging machines equipped with a pre-stretching device have the drawback of not allowing perfect exploitation of the attractive stretching range of between 50 and 400%. Indeed, the pre-stretching devices are adjusted at the start of the program so as to obtain a certain degree of stretching which takes into account the material of the film, the profile of the load to be packaged, the risk of crushing the corners, in particular in the case of fragile cardboard packages and other parameters. We are therefore led to take precautionary measures initially so that the plastic film does not rupture during the machine's operation, these measures actually resulting in a sharp reduction in the upper limit of the aforementioned range.

DE-A-2 750 780 décrit le contrôle de la vitesse d'une bobine à partir de laquelle un film est déroulé, au moyen d'un système de freinage électromagnétique. La vitesse de la bobine varie en fonction d'une « mesure de tension de film mais cette mesure est en fait la variation de l'angle d'arrivée de la pellicule au poste d'utilisation et dépend de la forme (angulaire) de la charge à emballer.DE-A-2 750 780 describes the control of the speed of a reel from which a film is unwound, by means of an electromagnetic braking system. The reel speed varies according to a “film tension measurement, but this measurement is in fact the variation of the angle of arrival of the film at the station of use and depends on the (angular) shape of the load to be packed.

L'invention a pour but de remédier à cette déficience d'exploitation de la plage d'allongement précitée par une adaptation continue du degré de pré-étirage du film de matière plastique à la tension engendrée dans ce film par l'enveloppement de la charge à emballer, afin que la somme de l'allongement produit par le pré-étirage et de l'allongement supplémentaire produit par la tension créée dans le film avant son arrivée sur la charge à emballer ne dépasse pas l'allongement de rupture.The object of the invention is to remedy this operating deficiency in the above-mentioned elongation range by continuously adapting the degree of pre-stretching of the plastic film to the tension generated in this film by the wrapping of the load. to be packaged, so that the sum of the elongation produced by the pre-stretching and the additional elongation produced by the tension created in the film before it reaches the load to be packaged does not exceed the breaking elongation.

Pour résoudre ce problème, il est prévu conformément à la présente invention, un procédé de régulation du degré de pré-étirage d'un film de matière plastique étirable qui passe sur au moins un cylindre de pré-étirage avant de parvenir à un poste d'utilisation, notamment en vue de l'emballage de charges, en particulier de charges palettisées, permettant d'éviter que la somme de l'allongement produit par le pré-étirage et de l'allongement supplémentaire produit par la tension créée dans le film avant son arrivée sur la charge à emballer soit supérieure à l'allongement de rupture, ce procédé consistant à :

  • - capter de façon continue la tension dans la partie de film comprise, en considérant le sens de déplacement du film, entre le dernier cylindre de pré-étirage et le poste d'utilisation,
  • - faire varier la vitesse d'au moins un cylindre de pré-étirage en correspondance à la tension captée.
To solve this problem, there is provided in accordance with the present invention, a method of regulating the degree of pre-stretching of a film of stretchable plastic material which passes over at least one pre-stretching cylinder before reaching a station use, in particular for the packaging of loads, in particular palletized loads, making it possible to avoid the sum of the elongation produced by the pre-stretching and the additional elongation produced by the tension created in the film before its arrival on the load to be packaged is greater than the elongation at break, this process consisting in:
  • - continuously sensing the tension in the part of the film included, considering the direction of movement of the film, between the last pre-stretching cylinder and the station of use,
  • - varying the speed of at least one pre-stretching cylinder in correspondence with the sensed tension.

Selon une autre particularité du procédé précité, dans le cas où on dispose d'au moins deux cylindres de pré-étirage, on fait varier la vitesse du dernier cylindre de pré-étirage.According to another particular feature of the aforementioned method, in the case where there are at least two pre-stretching cylinders, the speed of the last pre-stretching cylinder is varied.

Dans un mode d'application hautement préféré, le procédé est mis en oeuvre pour l'emballage d'une charge.In a highly preferred mode of application, the method is used for packaging a load.

L'invention concerne également un dispositif de régulation du degré de pré-étirage d'un film de matière plastique étirable, utilisable notamment dans une machine d'emballage de charges, en particulier de charges palettisées, permettant d'éviter que la somme de l'allongement produit par le pré-étirage et de l'allongement supplémentaire produit par la tension créée dans le film avant son arrivée sur la charge à emballer soit supérieure à l'allongement de rupture, comportant au moins deux cylindres étireurs successifs dont au moins un tourne à une vitesse réglable, la vitesse périphérique du cylindre aval étant supérieure ou égale à la vitesse périphérique du cylindre amont, et des moyens pour régler la vitesse d'application du film sur la charge de façon que cette vitesse soit égale ou inférieure à la vitesse périphérique du cylindre aval, caractérisé en ce qu'il comprend :

  • - un moyen de captage continu de la tension du film dans sa partie comprise, en considérant le sens de déplacement du film, entre le dernier cylindre étireur et le point d'arrivée sur la charge,
  • - une servo-commande recevant en permanence le signal de sortie du moyen de captage de tension de film et assurant sa comparaison avec une valeur de consigne de façon à faire varier en correspondance la vitesse d'au moins un des cylindres de pré-étirage.
The invention also relates to a device for regulating the degree of pre-stretching of a film of stretchable plastic material, usable in particular in a machine for packaging loads, in particular palletized loads, making it possible to prevent the sum of the '' elongation produced by the pre-stretching and the additional elongation produced by the tension created in the film before its arrival on the load to be packaged either greater than the elongation at break, comprising at least two successive stretching cylinders, at least one of which rotates at an adjustable speed, the peripheral speed of the downstream cylinder being greater than or equal to the peripheral speed of the upstream cylinder, and means for adjusting the speed applying the film to the load so that this speed is equal to or less than the peripheral speed of the downstream cylinder, characterized in that it comprises:
  • a means for continuously capturing the tension of the film in its included part, by considering the direction of movement of the film, between the last stretching cylinder and the point of arrival on the load,
  • a servo-control permanently receiving the output signal from the film tension capture means and ensuring its comparison with a set value so as to vary in correspondence the speed of at least one of the pre-stretching cylinders.

Le dispositif conforme à l'invention peut encore comporter les caractéristiques ci-après, considérées isolément ou selon toutes leurs combinaisons techniquement possibles :

  • - le moyen de captage de tension comprend un dispositif avec au moins un rouleau de renvoi servant à former une boucle dans le film et un capteur de tension de film placé en regard du rouleau de renvoi de manière à analyser son déplacement se produisant en fonction de la tension du film ;
  • - ledit rouleau de renvoi du dispositif de formation de boucle est monté sur un support de façon à se déplacer par translation ;
  • - ledit rouleau de renvoi du dispositif de formation de boucle est monté sur un support de façon à se déplacer par rotation ;
  • - le dispositif est caractérisé en ce qu'on fait varier la vitesse du dernier cylindre de pré-étirage, ledit cylindre étant actionné par un moteur qui est sollicité de façon continue par une servo-valve incorporée à la servo-commande et réagissant aux signaux fournis par le capteur de tension de film,
  • - le moteur est un moteur hydraulique.
The device according to the invention may also include the following characteristics, considered in isolation or in all their technically possible combinations:
  • the tension sensing means comprises a device with at least one deflection roller serving to form a loop in the film and a film tension sensor placed opposite the deflection roller so as to analyze its displacement occurring as a function of film tension;
  • - Said return roller of the loop forming device is mounted on a support so as to move by translation;
  • - Said return roller of the loop forming device is mounted on a support so as to move by rotation;
  • - The device is characterized in that the speed of the last pre-stretching cylinder is varied, said cylinder being actuated by a motor which is continuously actuated by a servo-valve incorporated in the servo-control and reacting to the signals supplied by the film tension sensor,
  • - the motor is a hydraulic motor.

Le procédé et le dispositif selon l'invention sont applicables en particulier à l'emballage de charges, notamment des charges palettisées se composant d'un certain nombre de paquets élémentaires. Il est d'ailleurs à noter que l'invention est applicable aussi bien lorsque l'emballage est réalisé par enroulement progressif du film autour de la charge que dans le cas où on opère par la méthode dite « en rideau », c'est-à-dire où la charge est poussée contre le film de matière plastique de manière à être enveloppée dans son ensemble.The method and the device according to the invention are applicable in particular to the packaging of loads, in particular palletized loads consisting of a certain number of elementary packages. It should also be noted that the invention is applicable both when the packaging is carried out by progressive winding of the film around the load and in the case where it is operated by the so-called “curtain” method, that is to say ie where the charge is pushed against the plastic film so as to be wrapped as a whole.

D'autres avantages et caractéristiques de l'invention seront mis en évidence dans la suite de la description, donnée à titre d'exemple non limitatif, en référence aux dessins annexés dans lesquels :

  • Figure 1 est un diagramme donnant la tension du film de matière plastique en fonction de l'angle de rotation de la charge, les différentes positions angulaires de la charge étant mises en évidence.
  • Figure 2 est une vue en plan schématique d'une machine d'emballage du type à enveloppement progressif, équipée d'un exemple de réalisation du dispositif de régulation de pré-étirage de film conforme à l'invention, et
  • la figure 3 est une vue en plan schématique d'une machine d'emballage du type à enveloppement en rideau, équipée d'un autre exemple de réalisation du dispositif de régulation de pré-étirage de film conforme à l'invention.
Other advantages and characteristics of the invention will be highlighted in the following description, given by way of nonlimiting example, with reference to the appended drawings in which:
  • Figure 1 is a diagram showing the tension of the plastic film as a function of the angle of rotation of the load, the different angular positions of the load being highlighted.
  • FIG. 2 is a schematic plan view of a packaging machine of the progressive wrapping type, equipped with an exemplary embodiment of the device for regulating the pre-stretching of film according to the invention, and
  • Figure 3 is a schematic plan view of a curtain wrapping type packaging machine, equipped with another embodiment of the film pre-stretch control device according to the invention.

Avant de passer à la description proprement dite du procédé et du dispositif de régulation de pré-étirage de film conformes à l'invention, on va expliquer la structure de principe d'une machine d'emballage équipée d'un dispositif de pré-étirage de film. Ainsi la fig. représente une machine opérant par enveloppement progressif d'une charge P qui est placée sur une table tournante T. Cette charge peut être formée de plusieurs paquets unitaires qui sont maintenus en place sur une palette sous la forme d'un ensemble qui doit être enveloppé d'un film de matière plastique. Ce film, désigné par FP sur la fig. 2 est déroulé d'une bobine B et il passe d'abord sur un rouleau de renvoi R, puis sur des moyens de pré-étirage, tels que C, et C2, qui sont constitués dans l'exemple représenté par des cylindres revêtus d'une substance, caoutchoutée ou autre, exerçant une grande force de frottement sur le film de matière plastique. Le film subit ainsi un premier pré-étirage sur le cylindre C, et un second pré-étirage sur le cylindre C2 qui tourne à une vitesse supérieure à Ci. Dans les réalisations connues, le film parvient ensuite directement sur la charge P pour assurer son enveloppement. Une telle structure correspond à ce qu'on appelle une machine à enveloppement progressif, qui enroule progressivement le film FP autour de la charge P, la table tournante pouvant exécuter un mouvement de translation verticale.Before going on to the actual description of the process and of the device for regulating the pre-stretching of film according to the invention, we will explain the basic structure of a packaging machine equipped with a pre-stretching device. of movie. Thus fig. represents a machine operating by progressive wrapping of a load P which is placed on a turntable T. This load can be formed of several unitary packages which are held in place on a pallet in the form of an assembly which must be wrapped d 'a plastic film. This film, designated by FP in fig. 2 is unwound from a reel B and it passes first on a deflection roller R, then on pre-stretching means, such as C, and C 2 , which are constituted in the example represented by coated rolls of a substance, rubberized or otherwise, exerting a great friction force on the plastic film. The film thus undergoes a first pre-stretching on the cylinder C, and a second pre-stretching on the cylinder C 2 which rotates at a speed greater than Ci. In known embodiments, the film then reaches the load P directly to ensure his wrap. Such a structure corresponds to what is called a progressive wrapping machine, which gradually wraps the film FP around the load P, the rotary table being able to execute a vertical translational movement.

Il existe également une autre structure de machine d'emballage, à laquelle l'invention peut être appliquée et qui est mise en évidence sur la fig.3. On a affaire dans ce cas à une machine d'emballage du type à enveloppement en rideau, suivant lequel la charge P est enveloppée en éant poussée dans la direction F contre le film FP1, FP2 déroulé simultanément de deux bobines B1, B2. Il est à noter qu'initialement les deux parties de film déroulées des bobines B1, B2 sont soudées avant le début du mouvement de transfert de la charge dans la direction F de façon à former devant cette charge ce qu'on appelle un « rideau ». Après achèvement du mouvement de transfert de la charge P dans la direction F, les deux brins de film FP1, FP2 sont rapprochés à l'aide d'un dispositif, non représenté, de manière à envelopper complètement la charge et les deux brins FP1, FP2 sont soudés ensemble en arrière de la charge pour terminer ainsi son emballage. Une machine de ce genre assure également un pré-étirage des deux brins FP1, FP2 du film de matière plastique à l'aide de moyens d'étirage appropriés et connus, qui ont été matérialisés sur la fig. 3 par les deux paires de cylindres C,, C2 et C'i, C'z. Dans la machine connue, les brins de film FP1 et FP2 arrivent ensuite directement sur la charge à emballer.There is also another structure of a packaging machine, to which the invention can be applied and which is highlighted in FIG. 3. We are dealing in this case with a wrapping machine of the curtain wrapping type, according to which the load P is wrapped by being pushed in the direction F against the film FP1, FP2 unwound simultaneously from two reels B1, B2. It should be noted that initially the two parts of film unwound from the reels B1, B2 are welded before the start of the load transfer movement in the direction F so as to form in front of this load what is called a "curtain" . After completion of the load transfer movement P in the direction F, the two film strands FP1, FP2 are brought together using a device, not shown, so as to completely envelop the load and the two strands FP1, FP2 are welded together behind the load to complete its packaging. A machine of this kind also provides a pre-stretching of the two strands FP1, FP2 of the plastic film using stretching means. suitable and known, which have been materialized in FIG. 3 by the two pairs of cylinders C ,, C 2 and C ' i , C' z . In the known machine, the film strands FP1 and FP2 then arrive directly on the load to be packaged.

Comme on l'a précisé dans le préambule, les matières plastiques utilisées pour former un film d'emballage, notamment du polyéthylène de faible densité, peuvent subir un étirage de 400 % jusqu'à la rupture tout en présentant, après dépassement de la limite élastique qui correspond à peu près à un allongement de 40 à 50 %, une amélioration sensible de leurs propriétés, notamment la résistance à la traction. Le pré-étirage d'un film de matière plastique avant son arrivée sur la charge à emballer est par conséquent extrêmement intéressant du fait que non seulement on améliore les propriétés du film mais qu'en outre on réalise des économies importantes de matières puisqu'il est possible, en l'allongeant considérablement dans la plage indiquée ci-dessus, d'emballer beaucoup plus de produits avec la même longueur initiale de film. Cependant, si on pousse trop loin le pré-étirage en se rapprochant excessivement de la limite de 400 %, il risque de se produire une rupture de film. En effet les charges à emballer sont souvent constituées par des ensembles de paquets unitaires de forme parallélépipédique ou cubique et il se produit, au cours du mouvement de rotation ou de translation de la charge à emballer une variation de la tension engendrée dans le film de matière plastique. Cela a été mis en évidence sur la fig. 1, qui est une représentation graphique donnant la tension dans le film de matière plastique en fonction de l'angle a de rotation de la charge. On a indiqué à la partie supérieure du graphique une courbe d'allure sinusoïdale, variant entre un maximum et un minimum et qui représente la tension dans le film de matière plastique au cours du passage du point S dans les différentes positions désignées par S1, S2, S3, S4 et S5 sur la fig. 1. Si l'on ne tient pas compte de cette tension du film, on risque de se rapprocher excessivement de la limite d'allongement de 400 % pour laquelle le film se rompt. Or on ne tient absolument pas compte de la tension du film dans les machines connues équipées de dispositifs de pré-étirage et il en résulte que les utilisateurs prennent des mesures de précaution se traduisant par une limitation du degré de pré-étirage à une valeur bien inférieure à celle qui pourrait être adoptée dans les conditions optimales.As specified in the preamble, the plastics used to form a packaging film, in particular low density polyethylene, can undergo a stretching of 400% until breaking while having, after exceeding the limit elastic which roughly corresponds to an elongation of 40 to 50%, a significant improvement in their properties, in particular the tensile strength. The pre-stretching of a plastic film before it arrives on the load to be packaged is therefore extremely advantageous because not only does it improve the properties of the film but also makes significant savings in materials since It is possible, by lengthening it considerably in the range indicated above, to pack many more products with the same initial length of film. However, if the pre-stretch is pushed too far, approaching the 400% limit excessively, there is a risk of a film rupture. In fact, the loads to be packaged often consist of sets of unitary packages of parallelepipedic or cubic shape and there occurs, during the rotational or translational movement of the load to be packaged, a variation in the tension generated in the film of material. plastic. This has been highlighted in fig. 1, which is a graphic representation giving the tension in the plastic film as a function of the angle a of rotation of the load. We have indicated at the top of the graph a sinusoidal curve, varying between a maximum and a minimum and which represents the tension in the plastic film during the passage of the point S in the different positions designated by S1, S2 , S3, S4 and S5 in fig. 1. If this tension of the film is not taken into account, there is a risk of getting too close to the elongation limit of 400% for which the film breaks. However, the tension of the film is absolutely not taken into account in known machines equipped with pre-stretching devices and it follows that users take precautionary measures resulting in a limitation of the degree of pre-stretching to a good value. lower than that which could be adopted under optimal conditions.

Le procédé et le dispositif conformes à l'invention ont pour objectif de remédier aux déficiences des réalisations connues en tenant compte simultanément du degré de pré-étirage du film de matière plastique et de la tension engendrée dans celui-ci à son arrivée sur la charge à emballer.The aim of the method and the device according to the invention is to remedy the shortcomings of known embodiments by simultaneously taking into account the degree of pre-stretching of the plastic film and the tension generated in it when it arrives on the load. to pack.

Ainsi, sous son aspect le plus général, le procédé selon l'invention pour la régulation du degré de pré-étirage d'un film de matière plastique étirable qui passe, lors de l'emballage d'une charge, sur un ou plusieurs moyens de pré-étirage avant de parvenir à la charge, ledit procédé consistant à capter de façon continue la tension dans la partie de film comprise, en considérant le sens de déplacement du film, entre le dernier moyen de pré-étirage et la charge à emballer, et à faire varier, en correspondance à la tension captée, la vitesse d'au moins un desdits moyens de pré-étirage et/ou de la charge, afin que la somme de l'allongement produit par le pré-étirage et de l'allongement supplémentaire produit par la tension créée dans le film avant son arrivée sur la charge à emballer ne dépasse pas l'allongement de rupture.Thus, in its most general aspect, the method according to the invention for regulating the degree of pre-stretching of a film of stretchable plastic material which passes, during the packaging of a load, on one or more means pre-stretching before reaching the load, said method consisting in continuously sensing the tension in the part of the film included, considering the direction of movement of the film, between the last pre-stretching means and the load to be packaged , and to vary, in correspondence to the sensed tension, the speed of at least one of said pre-stretching means and / or of the load, so that the sum of the elongation produced by the pre-stretching and of the The additional elongation produced by the tension created in the film before it reaches the load to be packaged does not exceed the elongation at break.

Sous un aspect particulier, dans le cas où les moyens de pré-étirage sont constitués par des cylindres étireurs actionnés par des moteurs indépendants, le procédé consiste à capter de façon continue la tension dans le film dans la zone située entre le dernier cylindre de pré-étirage et la charge à réagir sur la vitesse de ce dernier cylindre de pré-étirage en correspondance à la tension captée.In a particular aspect, in the case where the pre-stretching means are constituted by stretching cylinders actuated by independent motors, the method consists in continuously sensing the tension in the film in the area between the last pre-stretching cylinder. -drawing and the load to react on the speed of this last pre-stretching cylinder in correspondence with the sensed tension.

Ainsi le procédé selon l'invention permet d'adapter de façon continue les conditions de marche de la machine aux paramètres régissant l'emballage d'une charge déterminée, notamment la forme de cette charge, sa fragilité dans les coins, sa vitesse d'entraînement, la nature et la résistance du film de matière plastique, etc.Thus the method according to the invention makes it possible to continuously adapt the operating conditions of the machine to the parameters governing the packaging of a determined load, in particular the shape of this load, its fragility in the corners, its speed of entrainment, nature and strength of the plastic film, etc.

Il est en outre à noter que le procédé selon l'invention n'est absolument pas limité au domaine de l'emballage et qu'il est possible d'envisager son application dans tous les cas où il est avantageux, pour des raisons d'amélioration des propriétés de résistance du film et de rentabilité, d'assurer son pré-étirage avant sa mise en oeuvre.It should also be noted that the method according to the invention is absolutely not limited to the field of packaging and that it is possible to envisage its application in all cases where it is advantageous, for reasons of improvement of the properties of resistance of the film and of profitability, of ensuring its pre-stretching before its implementation.

Les figures 2 et 3 mettent en évidence la mise en pratique du procédé selon l'invention dans les deux types de machines d'emballage qui ont été définis ci-dessus.Figures 2 and 3 highlight the implementation of the method according to the invention in the two types of packaging machines which have been defined above.

On va d'abord considérer le mode de réalisation de la fig. 2 qui correspond à la machine d'emballage à enveloppement progressif. Après le pré-étirage du film par les cylindres C1, C2, il est nécessaire de mesurer la tension de ce film dans le brin compris entre le point S et le point de tangence au cylindre C2 de manière à pouvoir réagir sur les conditions de pré-étirage du film pour empêcher sa rupture tout en exploitant au maximum la plage d'étirage disponible.We will first consider the embodiment of FIG. 2 which corresponds to the progressive wrapping packaging machine. After the pre-stretching of the film by the cylinders C1, C2, it is necessary to measure the tension of this film in the strand between the point S and the point of tangency to the cylinder C2 so as to be able to react on the pre conditions stretching the film to prevent it from breaking while making the most of the stretching range available.

Dans l'exemple de réalisation représenté sur la fig. 2, le dispositif de régulation de degré de pré-étirage du film de matière plastique comprend un moyen de captage de tension de film comportant les éléments suivants :

  • a) un mécanisme de formation de boucle dans le film FP, qui est placé entre le dernier moyen d'étirage constitué par le cylindre étireur C2 et la charge à emballer P ; ce mécanisme est constitué. dans l'exemple représenté, par un rouleau de renvoi R3 qui est monté élastiquement sur un support, désigné par SP sur la fig. 2 et qui, suivant sa conception de montage, peut exécuter un mouvement rectiligne ou bien un mouvement circulaire ; la fig. 2 met en évidence un autre rouleau de renvoi R2 dont la fonction sera précisée dans la suite ;
  • b) un capteur de tension de film CT, placé en regard du rouleau R3 de manière à capter le déplacement rectiligne ou circulaire dudit rouleau, qui est fonction de la tension engendrée dans le film de matière plastique FP au cours de l'enveloppement de la charge P.
In the embodiment shown in FIG. 2, the device for regulating the degree of pre-stretching of the plastic film comprises a film tension sensing means comprising the following elements:
  • a) a loop formation mechanism in the film FP, which is placed between the last stretching means constituted by the stretching cylinder C2 and the load to be packaged P; this mechanism is constituted. in the example shown, by a deflection roller R3 which is resiliently mounted on a support, designated by SP in FIG. 2 and which, depending on its mounting design, can execute a rectilinear movement or a circular movement; fig. 2 highlights another return roller R2 whose function will be explained below;
  • b) a film tension sensor CT, placed opposite the roller R3 so as to pick up the rectilinear or circular movement of said roller, which is a function of the tension generated in the plastic film FP during the wrapping of the charge P.

Le dispositif de régulation comprend en outre une servo-commande SC qui est reliée au capteur de tension de manière à recevoir en permanence des signaux représentant la tension de film ; en outre la servo-commande SC est reliée par des conducteurs L1, L2, L3 respectivement au moteur M1 d'actionnement du cylindre étireur C1, au moteur M2 d'actionnement du cylindre étireur C2 et au moteur M3 d'entraînement de la table tournante T sur laquelle est placée la charge P. Elle comporte également des moyens pour analyser instantanément les conditions de tension réelles et de pré-étirage du film pour modifier en correspondance, comme indiqué par les liaisons L1, L2, L3, la vitesse d'un ou plusieurs des moteurs M1, M2, M3 afin que la somme de l'allongement provoqué par le pré-étirage et de l'allongement provoqué par la tension dans le brin final de film reste inférieure à la limite admissible.The regulating device further comprises a servo control SC which is connected to the tension sensor so as to permanently receive signals representing the film tension; furthermore the servo-control SC is connected by conductors L1, L2, L3 respectively to the motor M1 for actuating the stretching cylinder C1, to the motor M2 for actuating the stretching cylinder C2 and to the motor M3 for driving the rotary table T on which the load P is placed. It also includes means for instantaneously analyzing the real tension and pre-stretching conditions of the film to modify in correspondence, as indicated by the links L1, L2, L3, the speed of a or more of the motors M1, M2, M3 so that the sum of the elongation caused by the pre-stretching and the elongation caused by the tension in the final film strand remains less than the admissible limit.

Selon un mode avantageux de réalisation de l'invention, la servo-commande LC réagit, en fonction du signal fourni par le capteur de tension de film, sur le dernier cylindre de pré-étirage C2 avant la charge en vue de modifier ainsi le degré de pré-étirage du film. Dans ce cas, il est avantageux d'assurer la commande du dernier cylindre de pré-étirage C2 par un moteur hydraulique M2 et il est alors prévu dans le servo-commande SC une servo-valve qui permet d'assurer ainsi une commande très précise de ce moteur hydraulique M2.According to an advantageous embodiment of the invention, the LC servo-control reacts, as a function of the signal supplied by the film tension sensor, on the last pre-stretching cylinder C2 before the load in order to thus modify the degree pre-stretching of the film. In this case, it is advantageous to ensure the control of the last pre-stretching cylinder C2 by a hydraulic motor M2 and there is then provided in the servo-control SC a servo-valve which thus ensures very precise control. of this M2 hydraulic motor.

Dans le cas du mode de réalisation représenté sur la fig. 3, qui correspond au mode d'enveloppement d'une charge « en rideau », l'application du procédé selon l'invention est analogue à ce qui a été représenté sur la fig. 2 ; ainsi on prévoit pour chacun des brins de film FP1 et FP2 un mécanisme de formation de boucle qui a été représenté sous une forme simplifiée, c'est-à-dire qu'il est simplement prévu un rouleau de renvoi Ri, R', ayant pour fonction de former la boucle de captage de tension entre le dernier cylindre de pré-étirage correspondant C2, C'2 et le point S1, S2 d'arrivée du brin de film correspondant SP1, SP2 sur la charge P. Le rouleau correspondant R3, R'3 est monté sur un support SP1, SP'1 pouvant exécuter un mouvement rectiligne ou circulaire ; il est prévu en regard du rouleau de renvoi correspondant R3, R'3 un capteur CT,, CT2, qui a pour fonction de mesurer la tension dans le brin de film associé FP1, FP2 par analyse du déplacement rectiligne ou circulaire du rouleau correspondant R3, R'3. Les signaux des deux capteurs CTI, CT2 sont appliqués à une servo-commande SC qui les analyse et qui réagit en conséquence sur un ou plusieurs des moteurs M1, M2, M'1, M'2 d'entraînement des cylindres de pré-étirage C1, C2, C'1. C'2 et/ou sur le moteur M3 assurant la translation de la charge P.In the case of the embodiment shown in FIG. 3, which corresponds to the mode of wrapping a load "curtain", the application of the method according to the invention is similar to what has been shown in FIG. 2; thus, for each of the film strands FP1 and FP2, a loop-forming mechanism has been provided which has been shown in a simplified form, that is to say a return roller R i , R ′ is simply provided, having the function of forming the tension sensing loop between the last corresponding pre-stretching cylinder C2, C'2 and the point S1, S2 of arrival of the corresponding film strand SP1, SP2 on the load P. The corresponding roller R3, R'3 is mounted on a support SP1, SP'1 which can execute a rectilinear or circular movement; next to the corresponding return roller R3, R'3 there is a sensor CT ,, CT 2 , which has the function of measuring the tension in the associated film strand FP1, FP2 by analysis of the rectilinear or circular displacement of the corresponding roller R3, R'3. The signals from the two sensors CT I , CT 2 are applied to a servo control SC which analyzes them and which reacts accordingly on one or more of the motors M1, M2, M'1, M'2 for driving the pre cylinders. -drawing C1, C2, C'1. C'2 and / or on the motor M3 ensuring the translation of the load P.

En considérant à nouveau la fig. 2, il est à noter que le rouleau de renvoi R2 placé immédiatement avant la charge P est prévu pour modifier l'angle d'arrivée du brin de film FP sur la charge afin d'adapter cet angle aux conditions d'emballage de la charge ; en effet, lorsque la charge est fragile, par exemple lorsqu'elle est formé de paquets en carton mince dont les coins peuvent s'écraser, il est recommandé de réduire cet angle au minimum alors que dans d'autres applications un tel paramètre peut avoir moins d'importance.Again considering fig. 2, it should be noted that the deflection roller R 2 placed immediately before the load P is intended to modify the angle of arrival of the film strand FP on the load in order to adapt this angle to the packaging conditions of the charge ; in fact, when the load is fragile, for example when it is formed from thin cardboard packets whose corners can be crushed, it is recommended to reduce this angle to the minimum while in other applications such a parameter may have less important.

Comme indiqué ci-dessus, le procédé et le dispositif selon l'invention sont applicables au domaine particulier de l'emballage, notamment de charges formées de paquets unitaires et disposées sur des palettes, mais également d'une façon plus générale à tous les cas où il est nécessaire de contrôler le degré de pré-étirage d'un film de matière plastique en vue d'exploiter au maximum ces propriétés de résistance et également d'obtenir une rentabilité maximale de production.As indicated above, the method and the device according to the invention are applicable to the particular field of packaging, in particular of charges formed of unitary packages and placed on pallets, but also more generally in all cases. where it is necessary to control the degree of pre-stretching of a plastic film in order to make the most of these strength properties and also to obtain maximum production profitability.

Bien entendu l'invention n'est pas limitée aux exemples de réalisation ci-dessus décrits et représentés, à partir desquels on pourra prévoir d'autres modes et d'autres formes de réalisation, sans pour cela sortir du cadre de l'invention.Of course, the invention is not limited to the embodiments described above and shown, from which other modes and other embodiments can be provided, without thereby departing from the scope of the invention.

Claims (9)

1. Process for controlling the degree of prestretching of a stretchable plastic film which passes over at least one prestretching roll before arriving at a use station, particularly for the purpose of wrapping loads, especially palletized loads, making it possible to avoid the sum of the elongation produced by the prestretching and of the additional elongation produced by the tension created in the film before it arrives on the load to be wrapped being greater than the breaking elongation, characterized in that it consists in
- continuously sensing the tension in the part of the film included, when the direction of travel of the film is considered, between the last prestretching roll and the use station ; and
- causing the speed of at least one prestretching roll to vary correspondingly to the sensed tension.
2. Process according to Claim 1, characterized in that, in the case where at least two prestretching rolls are available, the speed of the last prestretching roll is varied.
3. Device for implementing the process according to Claim 1, especially for a machine for wrapping loads, in particular palletized loads, making it possible to avoid the sum of the elongation produced by the prestretching and of the additional elongation produced by the tension created in the film before it arrives on the load to be wrapped being greater than the breaking elongation, comprising at least two stretching rolls in-succession (C1, C2), at least one of which rotates at a speed which can be regulated, the peripheral speed of the downstream cylinder (C2) being greater than or equal to the peripheral speed of the upstream cylinder (C1), and means for regulating the speed of application of the film to the load so that this speed is equal to or lower than the peripheral speed of the downstream cylinder, characterized in that it comprises :
- a means (R3, CT) for continuously sensing the tension of the film (FP) in its part included, when the direction of travel of the film (FP) is considered, between the last stretching roll (C2) at the point of arrival on the load (P), and
- a servo control (SC) continuously receiving the output signal of the means (CT) for sensing the film tension and ensuring its comparison with a preset value so as to cause a corresponding variation in the speed of at least one of the prestretching rolls (C1, C2).
4. Device according to Claim 3, characterized in that the means for sensing tension comprise a device with at least one return roll (R3) used to form a loop in the film and a film tension sensor (CT) placed facing the return roll (R3) so as to analyse its displacement which is produced as a function of the film tension.
5. Device according to either of Claims 3 and 4, characterized in that the said return roll (R3) of the device for forming a loop is mounted on a support (SP) so as to be translationally displaced.
6. Device according to any one of Claims 3 to 5, characterized in that the said return roll (R3) of the device for forming a loop is mounted on a support (SP) so as to be rotationally displaced.
7. Device according to any one of Claims 3 to 6, characterized in that the speed of the last prestretching roll (C2) is varied, the said roll being driven by a motor (M2) which is continuously actuated by a servo valve incorporated in the servo control (SC) and reacting to the signals supplied by the film tension sensor (CT).
8. Device according to Claim 7, characterized in that the motor (M2) is a hydraulic motor.
EP19830401119 1982-06-07 1983-06-02 Method and device for regulating the pre-stretching of a plastic film, especifically in view of the packaging of a load Expired EP0096635B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8209878A FR2528020A1 (en) 1982-06-07 1982-06-07 METHOD AND DEVICE FOR REGULATING PRE-STRETCHING OF A FILM OF PLASTIC MATERIAL, ESPECIALLY FOR THE PACKAGING OF A LOAD
FR8209878 1982-06-07

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EP0096635A2 EP0096635A2 (en) 1983-12-21
EP0096635A3 EP0096635A3 (en) 1984-10-03
EP0096635B1 true EP0096635B1 (en) 1986-12-03

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US9725195B2 (en) 2008-01-07 2017-08-08 Lantech.Com, Llc Electronic control of metered film dispensing in a wrapping apparatus
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US11685567B2 (en) 2014-01-14 2023-06-27 Lantech.Com, Llc Dynamic adjustment of wrap force parameter responsive to monitored wrap force and/or for film break reduction

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EP0096635A3 (en) 1984-10-03
FR2528020A1 (en) 1983-12-09
ES8403415A1 (en) 1984-03-16
EP0096635A2 (en) 1983-12-21
ES523016A0 (en) 1984-03-16
DE3368034D1 (en) 1987-01-15

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