EP1648779B1 - Method and machine for heat-shrinking heat-shrinkable sleeves - Google Patents

Abstract

The present invention relates to a method and to a machine for heat-shrinking sleeves made from a film of heat-shrink plastics material and engaged individually on articles such as bottles. In accordance with the invention, the machine comprises a fixed structure, an article support arranged to move along a vertical central axis between a low position in which articles can be put into place or removed, and a high position in which an article is fully received in a pre-heater chamber surmounting a shrinkage chamber, together with a controller governing parameters of temperature, support travel speed, and time, during the operating sequences of the method. This enables ordinary consumers themselves to cause sleeves to be shrunk onto bottles.

Description

FIELD OF THE INVENTION

The present invention relates to the field of heat shrink sleeves made from a heat-shrinkable plastic film and strung individually on objects such as for example bottles.

BACKGROUND OF THE INVENTION

For thirty years there have already been retraction machines operating continuously, generally in the form of a tunnel furnace, for ensuring the retraction of a heat-shrinkable plastic sleeve threaded onto an object which is placed on a conveyor belt forming the bottom of the shrink tunnel. As the object passes from the upstream end to the downstream end of the tunnel furnace, with reference to the direction of travel of the conveyor belt, the sleeve threaded on each object softens and then retracts on said object.

Numerous techniques have been developed to control the anamorphosis of the printed patterns on the sleeve during the retraction of said sleeve on the object, as well as the quality of the retraction of the sleeve, which must be free of any crimping or imperfection at the exit of the oven-tunnel.

Among the many patent documents emanating from the plaintiff, reference may in particular be made to the documents FR-A-2,588,828 , FR-A-2,634,274 FR-A-2,758,387 , FR-A-2,797,944 , US-A-5,031,298 , US-A-4,325,762 , US-A-4,016,706 , US-A-4,092,382 , and US-A-3 873 655 .

It is also interesting to quote the document GB-A-1,485,942 . This document describes a laying technique heat-shrink sleeves on continuously moving bottles. The bottles are suspended by their neck, and a barrel with sleeve holders moves in synchronism under the bottles, with a rise of the sleeve to put it on the bottle from below, and a localized retraction of the sleeve at a level of annular band at half height to ensure the axial retention of the sleeve on the bottle before entering the assembly in a retraction tunnel. It should be noted that the articles to be lined with a sleeve are suspended and conveyed at a constant height, the axial movement affecting only the sleeves for placement on the objects, and that the ring for blowing hot air used only serves to retract an annular ring of the heat-shrink sleeve, the complete retraction later taking place in a shrink tunnel

The different machines thus produced are exclusively dedicated to an industrial use in the context of which it is sought to put sleeves on moving objects at a rate as high as possible, then to retract these sleeves on the associated objects, the steps taking place in continuous and exclusively in the presence of knowledgeable professionals.

There now appears a new need associated with the personalization of objects, in particular bottles, at the point of sale, with maximum latitude for the consumer to choose the sleeve to retract presenting the desired visual. Or the machines of the aforementioned type are totally unsuitable for use in a piecemeal by an average consumer who is totally unaware of retraction phenomena.

There is therefore a need for a technique that is both simple and efficient, making it possible to heat-shrink sleeves in a piecemeal unitary process, and this by any consumer way.

The professionals then turned to the realization of a small heat-shrinking machine, made in the form of a small tunnel oven at the entrance of which the consumer would put an object covered with the sleeve that he chose, and at the output of which the consumer would recover said object equipped with said sleeve retracted thereon.

However, it appears that the design of such small machines is more delicate than expected insofar as the objects concerned and the sleeves concerned can vary to a very large extent.

In particular, the same object can be conditioned at extremely variable temperatures depending on the point of sale. These extremely variable temperatures of the wall of the object in fact substantially modify the conditions for retraction of a heat-shrinkable sleeve on said objects. Of course also, the sizing of the object, in particular the sectional variations of said objects, will also have a great importance on the retraction conditions insofar as the retraction call can vary considerably from the top to the bottom of the object. . Finally, the nature (PET, PS, recyclable or not) and the thickness of the film constituting the sleeve to retract on the object can also vary, and also change the conditions of retraction.

To illustrate the state of the art with regard to retraction on a unitary object, mention may be made of the document EP-A-0 952 084 . This document describes a shrinkage system of a sheath on a gas cylinder, using a heating sleeve (internally equipped with heating wire windings) which is moved vertically to gradually retract the sheath on the gas cylinder, with a descent fast for preheating the sheath followed by a slower rise for the retraction of said sheath. It should be noted that the object therefore remains immobile during the retraction process, and that, if it is considered that the mobile heating sleeve defines a chamber, this same chamber first ensures preheating, then retraction.

There is therefore a pressing need for a retraction technique that is both simple to implement, and well suited to use in a piecemeal fashion by an ordinary consumer, without the latter having to worry about a problem. any adjustment according to the object and / or the sleeve that he has chosen.

Ideally, a retraction technique should be available which allows for implementation under widely varying conditions, particularly for the temperature at which the articles are packaged before being coated with a heat-shrinkable sleeve.

OBJECT OF THE INVENTION

The aim of the invention is to propose a method and a heat-shrinking machine that is both simple to implement and capable of coping with the extremely variable conditions encountered for the objects and the associated heat shrink sleeves, in particular at the temperature level. concerned, which are known to play a vital role in controlling the retraction of the sleeves on an object to have a perfect state after the retraction is complete.

GENERAL DEFINITION OF THE INVENTION

1. a) mise en place d'un objet unitaire sur un support mobile, un manchon étant enfilé sur ledit objet ;
2. b) transfert de l'objet avec son manchon dans une chambre de préchauffage à température contrôlée dans laquelle la chaleur régnante est obtenue par effet radiant, et maintien dudit objet dans ladite chambre pendant une durée prédéterminée afin de préparer de façon optimale le film constitutif du manchon pour sa rétraction ultérieure sur l'objet ;
3. c) passage, par déplacement à vitesse contrôlée selon une direction verticale (X), de l'objet avec son manchon dans une chambre de rétraction à température contrôlée qui est adjacente à la chambre de préchauffage, et dans laquelle la chaleur régnante est obtenue par soufflage d'air chaud et diffusion de l'air soufflé, afin de rétracter le manchon sur l'objet ; et
4. d) enlèvement hors du support de l'objet revêtu de son manchon rétracté, conformément à la revendication 1.

The aforementioned technical problem is solved according to the invention by a method of heat shrink sleeves made from a heat-shrinkable plastic film and strung individually on objects such as bottles, the method comprising the following successive steps:

1. a) placing a unitary object on a mobile support, a sleeve being threaded on said object;
2. b) transferring the object with its sleeve into a temperature-controlled preheating chamber in which the prevailing heat is obtained by radiant effect, and holding said object in said chamber for a predetermined time in order to optimally prepare the film constituting the sleeve for subsequent retraction on the object;
3. c) passing, by controlled-rate displacement in a vertical direction (X), the object with its sleeve in a temperature-controlled shrink chamber which is adjacent to the preheating chamber, and wherein the prevailing heat is obtained by blowing hot air and diffusing the blown air, in order to retract the sleeve on the object; and
4. d) removing from the support of the object coated with its retracted sleeve, according to claim 1.

Preferably, the parameters of temperatures, speeds of movement of the support and time are controlled according to the object concerned and the constituent film of the sleeve concerned. In particular, the parameters are controlled by a programmable controller responsible for managing the sequences of operations implemented in said method.

More preferably, the blowing of air into the shrink chamber is also used periodically to maintain the desired heat in the preheat chamber.

Advantageously also, the displacement of the mobile support during the transfer of the object into the preheating chamber and the passage of said object in the retraction chamber is performed in the same vertical direction. In particular, the support is rotated at a controlled rate on itself about a vertical axis before and during the passage of the object with its sleeve in the retraction chamber.

It can then be provided that the axial displacement of the mobile support is carried out at variable speed to optimize the duration of a complete cycle.

• un bâti fixe de machine ;
• un support d'objet monté pour se déplacer par rapport au bâti fixe le long d'un axe central vertical entre une position basse de pose ou d'enlèvement d'objet et une position haute dans laquelle l'objet est entièrement contenu dans une chambre de préchauffage surmontant une chambre de rétraction, ladite chambre de préchauffage étant constituée par une cheminée radiante portée par la chambre de rétraction en étant calée sur l'axe central vertical du support d'objet, et ladite chambre de rétraction étant raccordée à un ensemble de soufflage d'air chaud et incluant des composants servant à diffuser l'air soufflé ; et
• un automate pilotant les paramètres de températures, de vitesses de déplacement du support et de temps lors des séquences d'opérations du procédé, conformément à la revendication 8.

The invention also relates to a heat-shrinking machine intended to implement a process having at least one of the abovementioned characteristics, said machine being remarkable in that it comprises:

• a fixed machine mount;
• an object holder mounted to move relative to the fixed frame along a vertical central axis between a low position of placing or removing object and a high position in which the object is entirely contained in a chamber preheating device surmounting a retraction chamber, said preheating chamber being constituted by a radiant chimney carried by the retraction chamber being wedged on the vertical central axis of the object support, and said retraction chamber being connected to an assembly of blowing hot air and including components for diffusing the blown air; and
• an automaton controlling the parameters of temperatures, speeds of movement of the support and time during the sequences of operations of the method, according to claim 8.

Preferably, the object support is mounted so that it can also rotate about itself about its vertical central axis. In particular, the object support is arranged to wedge the object supported on the vertical central axis, and possibly also to protect all or part of the lower zone of said object.

Advantageously, the radiant chimney constituting the preheating chamber has a wall thickness and / or a cross section that is variable in case of significantly different shrinkage rates between the lower and upper zones of the sleeve to retract on the object.

According to another advantageous characteristic, the retraction chamber is of annular structure, and it is wedged on the vertical central axis of the object support.

Preferably, the annular retraction chamber has a cylindrical inner wall having at least one slot for the outlet of the diffused hot air. In particular, the inner wall of the annular shrink chamber has a plurality of slits that are inclined relative to the horizontal, and the components for diffusing the blown air are constituted by metal wool ribbons.

More preferably, the machine comprises an elevator which are secured on the one hand the object support and on the other hand a motor driving in rotation on itself of said object carrier, and a motor actuating said elevator for to ensure the vertical axial displacement of the object support, and the machine of said machine is connected to the two aforementioned engines as well as to the hot air blowing assembly associated with the retraction chamber, in order to drive different temperature, speed and time parameters. In particular, the automaton is programmable in particular to take into account the dimensions of the object concerned and the temperature of said object during the introduction into said machine, as well as the nature and thickness of the constituent film of the sleeve concerned. .

Advantageously finally, the machine comprises a protective cowling with a window allowing a manual introduction and removal of the object without risk of touching hot parts of said machine.

Other features and advantages of the invention will emerge more clearly in the light of the following description and the accompanying drawings, relating to a particular embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue en élévation illustrant une machine de thermorétraction mettant en oeuvre le procédé de l'invention ;
• la figure 2 est une vue de détail en perspective illustrant le support d'objet avec son moteur d'entraînement en rotation ;
• la figure 3 est une vue de détail en perspective illustrant la chambre annulaire de rétraction de la machine et l'ensemble de soufflage d'air chaud associé, ladite chambre étant surmontée d'une cheminée, ici illustrée en vue éclatée, formant la chambre de préchauffage de la machine;
• la figure 4 est une coupe axiale de la chambre annulaire de rétraction et de la chambre de préchauffage précitées, permettant de mieux distinguer les moyens permettant de diffuser l'air chaud soufflé ;
• la figure 5 illustre schématiquement les étapes du procédé de thermorétraction mis en oeuvre par la machine présentement illustrée, depuis la mise en place d'un objet unitaire avec un manchon enfilé sur ledit objet jusqu'à l'enlèvement de cet objet revêtu de son manchon rétracté ;
• la figure 6 est un diagramme illustrant schématiquement le pilotage par un automate programmable des différents paramètres intervenant dans les séquences d'opérations du procédé de l'invention.

Reference will be made to the accompanying drawings in which:

• the figure 1 is an elevational view illustrating a heat-shrinking machine implementing the method of the invention;
• the figure 2 is a detailed perspective view illustrating the object support with its rotating drive motor;
• the figure 3 is a detail view in perspective illustrating the annular shrink chamber of the machine and the associated hot air blowing assembly, said chamber being surmounted by a chimney, here illustrated in exploded view, forming the preheating chamber of the machine;
• the figure 4 is an axial section of the aforementioned annular retraction chamber and preheating chamber, to better distinguish the means for diffusing the hot air blown;
• the figure 5 schematically illustrates the steps of the heat-shrinking process carried out by the machine currently illustrated, since the introduction of a unitary object with a sleeve threaded on said object until the removal of this coated object of its retracted sleeve;
• the figure 6 is a diagram illustrating schematically the control by a programmable controller of the various parameters involved in the operation sequences of the method of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

We will first describe, referring to Figures 1 to 3 , a heat-shrinking machine according to the invention, which is intended to implement a method of heat shrink sleeves made from a heat-shrinkable plastic film and strung individually on objects such as bottles.

Although we are talking here about bottles, which represent certainly a preferred field of application, the invention is in no way limited to such a type of object, and may equally well apply to other types of containers or other types of objects intended to be coated by a heat-shrinkable sleeve carrying a visual desired by the consumer.

In these figures, there is a heat-shrinking machine 100 which is intended to allow heat-shrinking of sleeves made from a heat-shrinkable plastic film and threaded individually onto objects such as bottles. There is illustrated here a bottle 10 whose associated sleeve, which is threaded on said bottle, is referenced 11.

The machine 100 comprises a fixed frame 101, here made in the form of a support plate, on which various components are arranged. It is preferably provided a protective cowl allowing a manual introduction and removal of the object 10 without the risk of touching hot parts of the machine 100. Diagrammatically shown in phantom such a protective cover 200, which has a window 201 giving access to the area of an object support on which the consumer puts the unitary object 10 with its sleeve 11 threaded on said object, then retrieves the assembly after retraction of said sleeve on said object.

The fixed frame 101 carries a vertical column 102 which constitutes a guide element for an elevator slider 103 which is associated with said small column 102. The elevator slider 103 is equipped with a cantilevered assembly housing 104 above which is installed an object support 105. A motor 106 is part of this vertically displaceable assembly, and allows to ensure the rotation about itself, about a central vertical axis X, of the object support 105. The motor 106 will preferably be electric, but may in variant be pneumatically operated. A connector 106.1 is associated with the drive motor 106, and it is possible to distinguish on the figure 2 the connecting cable 106.2 leading to a general box 150 which is none other than a programmable controller responsible for managing the sequences of operations implemented in the heat shrink process of the invention.

The aforementioned movable element, comprising in particular the object support 105 with its associated motor 106 can thus move in a vertical direction, being guided in its movements by the column 102 on which slides the elevator carriage 103.

The object support 105 is thus mounted to move relative to the fixed frame 101 along the vertical central axis X, and this between a low position of installation or removal of object (position illustrated on the figure 1 ) and a high position in which the object 10 is entirely contained in a preheating chamber 140 surmounting an annular retraction chamber 130. The aforementioned chambers 130 and 140 will be described in more detail below with reference to the Figures 3 and 4 .

Although this is not mandatory, the object support 105 is thus mounted in this case to be able to rotate about itself about its vertical central axis X, this rotation appearing in fact interesting during the retraction step properly. said sleeve on the object.

To provide the vertical axial displacement of the aforementioned mobile assembly which includes the object support 105, there is provided here a drive assembly of the screw-nut type. Indeed, the elevator slider 103 is extended by a bracket 107 which is connected to a nut 108 which is engaged with the teeth of a threaded rod 109 of vertical axis, interposed between the frame 101 and an upper plate 110 connecting it to the balancer 102, to ensure a perfect verticality of said threaded rod 109. The threaded rod 109 is however not integral with the frame 101 and the wafer 110, but can rotate about its vertical axis, and this through means of associated drive which is constituted by a motor 116 whose output shaft 117 is connected to a gear housing 115 in engagement with the threaded rod 109. The motor 116 will preferably be electrical, but may alternatively be pneumatically operated . The electric motor 116 is connected by a cable 116.2 to the general machine of the machine 150. Thus, when the electric motor 116 is excited, so as to rotate its output shaft 117 in one direction or the other, this produces a rotation of the threaded rod 109 about its axis, in the corresponding direction, and consequently a rise or a descent of the nut 108. The rise or the descent of the nut 108 ensures the axial displacement of the crew mobile, and in particular the object carrier 105.

The axial displacement of the moving element is ensured between two precise levels, namely a lower level which corresponds to the position of installation or removal of object, and a higher level which corresponds to the housing of said object within the preheating chamber 140. Of course, end-of-stroke sensors will be provided associated with these two precise positions, with which, for example, the elevator slide 103 engages. Each of these two sensors will of course be connected to the motor control 116. and to the general automaton 150 (the aforementioned sensors are of conventional use and have not been illustrated here).

If we refer again to the figure 2 it is found that the object support 105 is arranged to wedge the object supported on the vertical central axis X, this with projecting pins 105.1. Indeed, during the rotation of the object support 105 around its central axis X, it is appropriate that the object, which will generally have a vertical central axis, is properly wedged on the vertical axis of rotation of the object support 105. There is also the presence of vertical fins projecting from the periphery of the object support 105, these fins being referenced 105.2. The object support 105 thus equipped is then able to protect all or part of the lower zone of the object placed on it thanks to these fins 105.2 which form heat shields when the base of the object is subjected a thermal field to retract the sleeve threaded on said object.

The figure 1 also makes it possible to distinguish a vertical column 112 rigidly secured to the machine frame 101, in the upper part of which is mounted a hot air blowing assembly 120. This assembly 120 comprises a housing 121 inside which are housed an electric fan and an electrical resistance generating infrared radiation heat when said resistance is traversed by an electric current. This hot air blowing assembly 120 is connected by a cable 120.2 to the general machine of the machine 150, this for controlling the temperature of the hot air blown by the blowing assembly 120. The housing 121 is equipped on a side surface thereof with a start / stop button 122 and an operating indicator light 123, as well as a manual adjustment knob 124 for varying the electrical current flowing through the heating resistor , and as a result of modulating the temperature of the air blown by this assembly of hot air blowing 120.

The output of the hot air blown is constituted by a cylindrical sleeve 125 rigidly fixed on the housing 121 of the assembly 120, which sleeve carries a nozzle 126 connected to a set here of annular structure forming a retraction chamber 130, which chamber is surmounted by a preheating chamber 140. In this case, the two chambers 130 and 140 are thus supported cantilevered by the pipes 125, 126 fixed to the housing 121 of the hot air blowing assembly 120. Naturally, an auxiliary support may be provided, the structure of which, however, will be designed to withstand the temperatures concerned.

The Figures 3 and 4 provide a better understanding of the particular structure and geometry of chambers 130 and 140.

The annular retraction chamber 130 is keyed on the vertical central axis X, and it is delimited above and below by flat rings 131 between which extend a cylindrical outer wall 132 and a cylindrical inner wall 133. The annular housing thus defined is supplied with hot air blown by the connection 135 to the nozzle 126. The hot air thus admitted into the annular space of the chamber 130 can only exit through openings here made in the form of slots 134. These slots 134 , formed in the inner wall 133 of the annular retraction chamber 130, are in this case inclined relative to the horizontal, this to have a perfect quality of retraction of the lower part of the sleeve threaded onto the object.

The cylindrical inner wall 133 thus delimits a central passage 139 whose axis coincides with the vertical central axis X of the aforementioned object support 105 and whose diameter is slightly greater than the external diameter of said object support 105. Thus, it is possible to pass the object support 105 with the object concerned on which the sleeve to be retracted is threaded into this central space 139 in order first of all to bring the object with its sleeve inside the preheating chamber 140, then to scroll this object, during the subsequent descent of said object, through the annular retraction chamber 130.

We will also note on the figure 4 the presence of components noted 136 which serve to diffuse the supply air admitted by the entry 135. Indeed, it is necessary to prevent the air escaping through the exit slots 134 exerts any excessive pressure on the outer wall of the sleeve during the passage of said sleeve opposite said slots. The aforementioned components 136 will for example consist of metal wool ribbons installed in the annular space of the chamber 130.

The preheating chamber 140 is constituted by a radiant chimney carried by the annular retraction chamber 130 being keyed on the X axis thereof. For the correct setting of the chimney 140, there are provided lower lugs 141 which are received in associated bores 138 formed on the upper ring 131 of the chamber 130. figure 3 the head of the bolts 137 solidarisant the two rings 131 defining the annular retraction chamber 130.

It is important to note that the chimney 140 is radiant, that is to say that its upper orifice is of course opening, and that its inner surface produces heat only by radiation, to the exclusion of any presence of special heating elements. The chimney 140 will for example be made of stainless steel.

If the object concerned has a weakly variable section, the shrinkage rate of the associated sleeve will vary little. In this case, it can be satisfied with a chimney 140 of cylindrical shape, and of constant thickness from one end to the other of said chimney. However, in certain situations, the shrinkage rate may vary considerably over the height of the object, particularly from the top to the bottom of the object. In this case, he can it would be interesting to modulate accordingly the inner section of the chimney 140. It may be expected that the chimney 140 has a wall thickness and / or a cross section that is variable. Of course, it may be provided for the upper part of the chimney with conical tightening equipping a cylindrical main part (variant not shown here).

We will now refer to the figure 5 which illustrates the different steps of the heat shrinkage process according to the invention.

In a), this is a preliminary step of placing a unitary object 10 on the mobile support 105, a sleeve 11 being threaded onto said object. Naturally, there will be sufficient space between the object support 105 in its lowest position and the bottom of the annular retraction chamber 130 so that an object can easily be placed on the support 105, regardless of the height of the object. -this.

In b), it is the transfer of the object 10 with its sleeve 11 in the preheating chamber 140 which is temperature controlled. It can be seen that the object support 105 then forms a sort of cover which substantially closes the lower part of the annular retraction chamber 130. The rise of the object 10 by the associated elevator is such that the lowest part of the object is at least above the highest level of the hot air outlet slots 134. It is then expected to hold the object in the preheating chamber 140 for a predetermined period of time in order to prepare optimally the film constituting the sleeve 11 for its subsequent retraction on the object 10. This preheating step is essential for obtaining a perfect retraction of the sleeve on the object taking into account all the characteristics of the object concerned, in particular the temperature of said object and its dimensions, and also the constituent film of the heat shrinkable sleeve concerned, in particular the nature and thickness of said film. The temperature prevailing inside the preheating chamber 140 and the residence time of the object with its sleeve inside said chamber, are controlled by the general PLC 150. This PLC 150 will preferably be programmable to in particular to take into account the dimensions of the object 10 concerned and its temperature during installation in said machine, as well as the nature and thickness of the constituent film of the sleeve 11 concerned.

Shortly before the end of the stay of the object in the preheating chamber 140, the heating of the air blown by the air blowing assembly 120 is switched on so that the air escaping from the slots 134 of the annular retraction chamber 130 is at the temperature which has been previously chosen. Upon reaching this predetermined temperature, the rotation of the object support 105 about its central axis X is engaged, as illustrated in b ').

The next step then begins, consisting of a controlled speed pass of the object 10 with its sleeve 11 in the annular shrink chamber 130 at controlled temperature, in order to retract the sleeve 11 on the object 10. In c) , there is illustrated an intermediate situation of the passage of the object 10 in the annular retraction chamber 130, which explains that only the lower part of said sleeve is shown retracted on the object.

The descent of the moving equipment with the object continues, with the passage of the entire height of the sleeve in front of the air outlet slots of the annular retraction chamber 130, which results in the final retraction of the sleeve on the 'object.

We then arrive at the situation illustrated in d), wherein the object support 105 has returned to its lowest position, this position corresponding to the removal from the support 105 of the object 10 coated with its sleeve 11 retracted.

It will be understood that the parameters of temperature, speeds of movement of the support 105 and time, are controlled by the programmable controller 150 according to the object 10 concerned and the constituent film of the sleeve 11 concerned. The programmable logic controller 150 is responsible for managing all the sequences of operations implemented in the method, and thus controls all the parameters concerned.

The figure 6 schematically illustrates the above control provided by the programmable controller 150.

With the connection 106.2, the motor 106 receives the speed (v) and operating time (t) instructions for each of the process steps. Similarly, the connection 116.2 sends the speed (v) and time (t) instructions to the motor 116 which ensures the axial displacement of the moving element. The connection 120.2 finally makes it possible to address the necessary instructions of current intensity (i) and time (t) to the hot air blowing unit 120 to obtain the desired temperature in the annular retraction chamber 130.

It can be seen from this diagram that no control is exercised here for the temperature prevailing inside the preheating chamber 140. This results from the fact that, in the present case, the blowing of air in the annular shrink chamber 130 is also used periodically to maintain the desired heat in the preheating chamber 140. This then makes it possible to avoid having specific means associated with the thermal field prevailing in the chimney 140, and to be then completely assured that the heat prevailing in said preheating chamber is obtained exclusively by radiant effect. The heat prevailing in the shrinkage chamber 130 is of course obtained by blowing hot air and diffusion of the blown air as indicated above.

On the diagram of the figure 6 Dotted lines have also been used for storing data associated with both the objects that may be involved and the constituent films of the associated sleeve. Of course, we will also have data related to the temperatures concerned, in order to be able to control automatically the operation of the machine in any country of the world, with in particular bottle temperatures ranging from 3 ° C to an ambient temperature of 35 ° C to 40 ° C.

As an indication, we will give some numerical values for the various operating parameters, it being understood that these are only illustrative examples.

For the preconditioning phase, after the laying on the dedicated base of the object with its sleeve threaded on said object, it ensures the stable maintenance with possible protection of the sensitive areas, and it is expected a rise of the mobile equipment to a speed of the order of five meters per second.

For the preheating step, a temperature of the order of 50 ° C. to 80 ° C. is provided inside the preheating chamber 140, with a holding time in said chamber ranging from about three to twenty seconds. It should be noted that the temperature will generally be significantly higher in the lower part of the chimney forming the preheating chamber 140 with, for example, a temperature of 75 ° C to 80 ° C at the bottom, and of the order of 40 ° C to 50 ° C in the upper part of said chimney.

For the retraction step itself, one provides blowing hot air at a temperature of 80 ° C to 90 ° C. The dedicated support is rotated at a speed of the order of 110 revolutions per minute, and the passage of the object in the annular retraction chamber 130 is preferably provided with a uniform speed of the order of five meters per minute. second. Once the object is completely out of the annular retraction chamber 130, it may be possible to provide an acceleration of the descent of the moving element, in order to reduce the overall cycle time.

As an indication, one arrives on the basis of the aforementioned parameters, to a complete cycle whose duration is of the order of one minute.

The invention is not limited to the embodiments which have just been described, but on the contrary covers any variant using, with equivalent means, the essential characteristics stated by the claims.

In particular, although it has been described the installation and retraction of a single sleeve on an object, it may be provided to coat the same object of several superimposed sleeves, set up and retracted simultaneously or successively. Similarly, the single sleeve may concern only a reduced area of the object, for example its upper part, central or low depending on the case.

Claims (18)

1. A method of heat-shrinking sleeves made from a film of heat-shrink plastics material and engaged individually on articles such as bottles, the method being characterized in that it comprises the following successive steps:

   a) placing a single article (10) on a moving support (105), a sleeve (11) being engaged on said article;

   b) transferring the article (10) together with its sleeve (11) into a pre-heater chamber (140) at a controlled temperature, the heating existing in said pre-heater chamber being obtained by the effect of radiation, and maintaining said article in said chamber for a predetermined duration so as to prepare the film constituting the sleeve (11) in optimum manner for subsequently shrinking the sleeve onto the article (10);

   c) passing the article (10) together with its sleeve (11) at a controlled speed through a shrinkage chamber (130) at controlled temperature, the shrinkage chamber being adjacent to the pre-heater chamber (140), the heating existing inside said shrinkage chamber being obtained by blowing in hot air and by diffusing the blown-in air, thereby causing the sleeve (11) to shrink onto the article (10); and

   d) removing the article (10) coated in its shrunk-on sleeve (11) from the support (105).
2. A method according to claim 1, characterized in that the parameters of temperature, travel speed of the support (105), and time are controlled as a function of the article (10) in question and of the film constituting the sleeve (11) in question.
3. A method according to claim 2, characterized in that the parameters are controlled by a programmable controller (150) governing the sequences of operations implemented in said method.
4. A method according to claim 1, characterized in that the air blown into the shrinkage chamber (130) is also made use of periodically for maintaining the desired temperature inside the pre-heater chamber (140).
5. A method according to any one of claims 1 to 4, characterized in that the movement of the moving support (105) while transferring the article (10) into the pre-heater chamber (140) and while causing said article to pass through the shrinkage chamber (130) takes place along said single vertical direction (X).
6. A method according to claim 5, characterized in that the support (105) is caused to revolve at controlled speed about a vertical axis (X) both before and during the passage of the article (10) together with its sleeve (11) through the shrinkage chamber (130).
7. A method according to claim 5 or claim 6, characterized in that the moving support (105) is caused to move axially at varying speed in order to optimize the duration of a complete cycle.
8. A heat-shrink machine (100) for implementing a method according to any one of claims 1 to 7, the machine comprising:

   - a stationary machine structure (101);

   - an article support (105) mounted to move relative to the stationary structure (101) along a vertical central axis (X) between a low position for installing or removing an article, and a high position in which the article is fully contained in a pre-heater chamber (140) surmounting a shrinkage chamber (130), said pre-heater chamber (140) being constituted by a radiant chimney (140) carried by the shrinkage chamber (130) and centered on the vertical central axis (X) of the article support (105), and said shrinkage chamber (130) being connected to a hot air blower assembly (120) and including components (136) serving to diffuse the blown-in air; and

   - a controller (150) governing the parameters of temperature, travel speed of the support (105), and time during the sequences of operations of the method.
9. A machine according to claim 8, characterized in that the article support (105) is mounted to be capable also of revolving about its own central vertical axis (X).
10. A machine according to claim 8 or claim 9, characterized in that the article support (105) is arranged to center the supported article (10) on the vertical central axis (X), and possibly also to protect all or part of the bottom zone of said article.
11. A machine according to claim 8, characterized in that the radiant chimney (140) constituting the pre-heater chamber is of variable wall thickness and/or cross-section in the event of there being significantly different shrinkage percentages between bottom and top zones of the sleeve (11) to be shrunk onto the article (10).
12. A machine according to any one of claims 8 to 11, characterized in that the shrinkage chamber (130) is annular in structure, and is centered on the vertical central axis (X) of the article support (105).
13. A machine according to claim 12, characterized in that the annular shrinkage chamber has a cylindrical inside wall (133) presenting at least one slot (134) for delivering the diffused hot air.
14. A machine according to claim 13, characterized in that the inside wall (133) of the annular shrinkage chamber (130) presents a plurality of slots (134) which are inclined relative to the horizontal.
15. A machine according to claim 8, characterized in that the components (136) for diffusing the blown-in air are constituted by strips of metal wool.
16. A machine according to claims 8 and 9, characterized in that it includes an elevator (103) secured firstly to the article support (105) and secondly to a motor (106) for causing said article support to revolve, together with a motor (116) actuating said elevator in order to cause the article support (105) to move vertically axially, and the controller (150) of said machine is connected to said two motors (106, 116) and to the hot air blower assembly (120) associated with the shrinkage chamber (130) in order to govern the various parameters of temperature, speed, and time.
17. A machine according to claim 16, characterized in that the controller (150) is programmable specifically to take account of the dimensions of the article (10) in question and the temperature of said article when it is put into place in said machine, and also to take account of the thickness and the nature of the film constituting the sleeve (11) in question.
18. A machine according to any one of claims 8 to 17, characterized in that it includes a protective cover (200) with a window (201) enabling the article (10) to be put into place and removed manually without any risk of touching hot parts of said machine.

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