FR3069232A1 - METHOD OF HOUSING AND THERMOSCELLING AND DEVICE FOR HOUSING AND THERMOSCELLING - Google Patents

Abstract

The method of covering and heat-sealing a cover (3) around a load (1) comprises: - supplying the load (1) arranged on a support (2), - putting the cover (3) on the load ( 1) pulling it downwards to face a fixing area (4), - heat-seal the cover (3) with the fixing area (4). The attachment zone (4) is formed by at least one plastic film ring under stress around the support (2) and / or the load (1) before heat sealing.

Description

COATING AND THERMOSCELLING METHOD AND COATING AND THERMOSCELLING DEVICE

Technical field of the invention

The invention relates to a covering and heat sealing process and to a covering and heat sealing device capable of implementing such a process.

State of the art

Conventionally, a load such as a package or a pallet is transported from its manufacturing site to a distribution area. During this transport, the load must be protected against dust and possibly against humidity. A step of protection by covering the side walls of the load by means of a plastic film, also called wrapping, is carried out.

During recovery, a plastic film is unwound from its support in order to continuously cover the side walls of the load to be protected by means of turns.

For certain applications, it is necessary to produce an integral or quasi-integral protective envelope which covers the faces of the load to be protected. It is known to produce recovery coils which are arranged to cover the lateral faces of the load to be protected. After the formation of these turns, a cap is deposited on the top of the load. The cap is then locked against the load by means of a new series of turns.

The cap and the coils protect the charge of the water which then flows on the protective plastic film. To form an envelope which is impermeable to the vertical runoff of water, the covering processes necessarily include a first step of forming a first set of ascending turns from the bottom of the load to the top of the load before depositing the cap. . The configuration of the first set of turns ensures a tiling which prevents water infiltration.

This solution is interesting but it requires a significant processing time which can lead to a non-negligible cost associated with the recovery operation.

In an alternative embodiment, illustrated in FIGS. 1, 2, 3 and 4, there is a method of covering a load 1 on a support 2. The method comprises the installation of a cover 3 on the load 1 then fixing the cover 3 with the load 1 and more particularly fixing it to a pallet 2 which supports the load 1.

Conventional cover processes use a long cover. As illustrated in FIG. 1, the height of the cover 3 is configured to cover the entire height of the load 1 and of the pallet 2. There is also an additional height of cover 3 which makes it possible to cover the underside of the pallet 2 In this way, it is possible to lift the pallet 2 to introduce part of the cover 3 under the pallet 2 and then to rest the pallet 2 on its support in order to block the cover 3.

A step of shrinking the cover 3 by heating is used simultaneously with the installation of the cover under the pallet. The retraction step illustrated in FIG. 2 makes it possible to fix the cover 3 with the pallet 2 using the transverse retraction of the cover 3. The lateral retraction prevents the cover 3 from being raised during the handling steps.

The lateral retraction step is generally associated with a longitudinal retraction which applies a constraint between the pallet 2 and the load 1.

With such a method, the bottom of the cover 3 closes or impedes access to the handling holes of the pallet 2. The material forming the cover 3 is not a very resistant material so that it is always possible to make one or more orifices to facilitate handling of the pallet 2. However, in many fields, this practice is prohibited because the formation of the openings by forcing on the cover 3 can cause deterioration of the cover 3 or even its tearing.

As the handling opening is not under control, there is a significant risk of seeing the pallet 2 get stuck with the handling machine. In this case, the load 1 can be damaged. It is also possible to damage the means for storing the pallets in a warehouse during attempts to separate the pallet 2 from the handling machine. In many warehouses, this type of covering is prohibited.

To avoid these inconveniences, it is then necessary to use pallets 2 with specific shapes and / or to form controlled clearances which make it possible to avoid any interaction between the cover and the handling machine. Again, these technological choices can lead to a significant additional cost of production. In some warehouses, it is not allowed to make specific holes in a long cover, even if fitted. There is therefore a significant difficulty linked to the use of long covers.

As illustrated in FIGS. 3 and 4, there is also a method of covering which comprises the installation of a cover 3 on the load 1 then the heat sealing of the load 1 at a fixing point 4 which is formed by a floor mat . The load 1 is placed on a pallet 2 and the floor mat separates the load 1 and the pallet 2. In this configuration, the floor mat secures the cover 3 with the load 1 during the heat sealing step.

This is faster than wrapping the side walls of the load and is better accepted in the warehouse. However, the cost of the floor mat and the constraint of installing the floor mat are not negligible elements and represent obstacles to the generalization of this solution. In fact, this embodiment is almost exclusively reserved for areas where the tightness of the load vis-à-vis the exterior is mandatory.

Subject of the invention

An object of the invention is to provide a method of hooding and heat sealing which is quick to implement and / or which is more economical than the methods of the prior art for forming an envelope integral with the load and / or the support. .

The covering and heat sealing process is remarkable in that it includes:

- Provide the load placed on a support,

- Put the cover on the load by pulling it down so as to come face to a fixing zone,

- Heat seal the cover with the fixing area.

The method is remarkable in that the fixing zone is formed by at least one ring of plastic film under stress around the support and / or the load before the heat-sealing.

In a development, the plastic film ring is formed by at least one turn.

Advantageously, the plastic film ring has at least one flat strip.

It is also advantageous to provide that the plastic film ring comprises at least one strand intended to come into direct contact with the cover.

In another development, the attachment zone comprises only one or two turns formed by a strand of plastic film.

In a particular embodiment, the plastic film ring is formed around the support.

Advantageously, the support is a pallet comprising a floor surmounting at least two pallet skids, the ring of plastic film being formed around the floor.

It is also advantageous to provide that the plastic film ring is formed around the load.

In a preferred embodiment, the attachment zone comprises a plurality of turns formed by a strip of plastic film, the consecutive turns overlapping.

Advantageously, the cover is stretched during the heat sealing step.

It is also possible to provide for the fixing zone to be formed after the load has come into contact with the support and before the cover is put on.

Advantageously, the fixing zone is formed before bringing the load into contact with the support.

Another object of the invention consists of a hooding and heat-sealing device which is more effective than the devices of the prior art in forming a waterproof envelope.

The covering and heat sealing device is remarkable in that it comprises:

- a wrapping device configured to deliver a plastic film forming at least one turn around a load or a support supporting the load, the at least one turn forming a fixing zone,

means for threading a cover over the load by pulling the cover down, the means for threading the cover being configured so that the cover comes facing the attachment zone,

- heat sealing means configured to heat seal the cover to the fixing zone,

- a control circuit configured to control the actuation of the heat sealing means after the cover has been threaded so that the cover is facing the fixing zone during heat sealing.

Brief description of the drawings

Other advantages and characteristics will emerge more clearly from the description which follows of particular embodiments of the invention given by way of nonlimiting examples and represented in the appended drawings, in which:

FIGS. 1 and 2 schematically represent two stages of a first method of covering according to the prior art,

FIGS. 3 and 4 schematically represent two stages of a second method of covering according to the prior art,

- Figures, 5, 6, 7, 8, 9, 10, 11 and 12 show, schematically, different embodiments of a fixing point of a method of covering according to the invention.

detailed description

The process of covering a load is more precisely a method of covering and heat sealing. The method comprises a first step of supplying a load 1 placed on a support 2.

Charge 1 can have any shape. For example, the load 1 can have a square, rectangular or circular section. The load 1 is placed on a support 2 which is advantageously a pallet, but it is possible to use another type of support 2. The support 2 can have any shape. Preferably, the horizontal section of the load 1 has the same shape as the horizontal section of the support 2 which facilitates the maintenance of the load 1.

A cover 3, also called sheath, is installed on the load 1 so as to cover the load 1. As illustrated in FIGS. 5, 6, 7, 8, 9, 10, 11 and 12, the cover 3 covers the top and at the at least partially the side walls of the load 1. Advantageously, the cover 3 covers the side walls of the load 1 over the entire length.

In a preferred embodiment, the bottom of the cover 3 faces the support 2.

The cover 3 is installed by threading it down so that part of the cover comes in front of a fixing zone 4.

A heat sealing step is then carried out so as to heat seal the cover 3 with the fixing zone 4. The heat sealing will create a mechanical connection between the cover 3 and the fixing zone 4. The heat sealing is carried out by heating the cover 3 and the attachment point 4.

In the prior art, the fixing zone 4 was formed by a floor mat which had to be installed before the load 1, which made the manufacturing process more complex and more expensive.

The inventors have observed that it is particularly advantageous to use at least one ring of plastic film to form the attachment zone 4. The ring completely surrounds the load 1 and / or the support 2 in a cutting plane which is preferably a horizontal section plane. The ring is under stress so that it clamps the load 1 and / or the support 2 in order to limit or even prevent vertical movement of the ring and of the cover 3 when a vertical stress is applied to the cover 3. The ring exerts a stress on the side walls of the load and / or the support

2. It is particularly advantageous to use a stretch film in order to have better management of the clamping force. Indeed, during tightening, it is possible to use a part of the elastic memory of the film which compensates for temperature deformations.

According to the embodiments, the plastic film used to form the ring can be a shrinkable plastic film, that is to say a film whose length and / or width decreases when it is heated. It is also possible to provide that the plastic film is produced in a stretch film, that is to say a film can be plastically deformed by traction. Depending on the configuration, the stretch film can be stretched before use to form the ring.

It is particularly advantageous to make the ring by means of one or more turns. This embodiment is easy to carry out and it makes it easier to manage the stress around the load 1 and / or the support 2. In fact, if the ring is initially deposited in the form of a closed ring made of heat-shrinkable material , this requires a handling step to place the ring which is slightly larger than the pallet to take full advantage of the retraction and obtain the desired clamping force.

By making the ring by wrapping, it is possible to better control the clamping force and therefore the mechanical support that exists between the cover and the pallet without passing the cover under the pallet. The ring can be formed by any suitable plastic material, for example by a heat-shrinkable material or by a stretchable material. Advantageously, the clamping force applied to the ring is between 0.2daN and 2daN. However, in the context of maintaining heavy or unstable loads and which require having greater stress forces by the cover, it is particularly advantageous to use a clamping force between 2daN and 10daN. Those skilled in the art will keep in mind that the intensity of the tightening is dependent on the material forming the pallet or the load, the material forming the plastic film as well as the retraction force of the cover to be contained. The intensity of the clamping force can be determined by making a ring around a support and pulling on this ring, for example with a dynamometer. When the ring has been moved from the 100mm support, the associated force is measured.

The turn of plastic film is advantageously made by wrapping which is a well known and mastered technique which makes it possible to form at least one turn which goes around the load 1 and / or of the support 2 in order to define the fixing zone 4. By wrapping, it is possible to easily define the tension applied to the turn or to the multiple turns so as to easily adapt to the constraints of manufacturing, heat sealing and handling.

Advantageously, the fixing zone 4 is formed by a turn or by a plurality of turns. Preferably, the consecutive turns at least partially overlap to improve the mechanical strength of the heat seal. Preferably, the attachment zone 4 comprises less than ten turns so as not to form an attachment zone which is too large or too bulky and not to penalize the duration of the production process with a step of forming the attachment zone 4 too long. In a particular embodiment, the fixing zone 4 only comprises one or two turns since this makes it possible to produce a fixing zone 4 with good mechanical resistance to the load 1 and a reduced duration of production.

In a particular embodiment, the turns of the attachment zone 4 can be, for example, flat strips or strands. By strand is meant that the turn is formed by several plastic films which are entangled to form a strand. As an alternative and through abuse of language, the strand can be formed by a single plastic film which is narrowed laterally to form a full or substantially full cylinder having the general shape of a strand or tube. The strand can be formed by a flat plastic film which is folded or twisted to make it a three-dimensional element. The strip represents a substantially two-dimensional plastic film, that is to say with a width and a length much greater than the thickness of the film. The thickness is preferably less than 1 mm. The strip deforms to adapt to the topography of load 1.

Depending on the configuration, it is possible to form the attachment zone 4 by means of one or more strands or by means of one or more flat strips. It is also possible to form the attachment zone 4 by means of one or more strands associated with one or more flat strips. The production of one or more strands is illustrated in Figures 7, 8, 9, 10, 11 and

12.

During the heat sealing step, the material forming the cover 3 reacts with the material forming the fixing zone 4 so as to create a mechanical connection. It has been observed that the mechanical fixing seems to be of better quality when the turn of the fixing zone 4 which comes into direct contact with the cover 3 is formed by a strand. In other words, the fixing zone 4 comprises at least one strand which comes into direct contact with the cover 3 during the heat sealing step.

Preparatory tests seem to show that the heat sealing between the strand and the cover 3 is as good as the heat sealing between the floor mat and the cover 3 of the prior art processes. It therefore seems advantageous to use a strand to ensure effective heat sealing since the operating conditions for heat sealing appear to be less restrictive.

Without wishing to be bound by any theory, the inventors believe that the excess material to be heated for the strand is compensated for by its static configuration throughout the heat sealing. Thus, even if the strand rises more slowly in temperature, it is easier to ensure continuous contact between the cover 3 and the strand.

The use of a fixing zone 4 formed by one or more turns and advantageously by wrapping makes it possible to precisely install the fixing zone 4 on the support 2 and / or on the load 1. There is no longer , as in the prior art, the complete covering of the side walls of the support 2 in order to take up fixation under the support 2.

In the case where the support 2 is a pallet, it is particularly advantageous to form the turns so as to cover the side walls which face the floor of the pallet. The floor is formed by a substantially horizontal board which surmounts the skids of the pallet, for example at least two skids of the pallet. The floor and the skids define the pallet handling orifices.

The ring being formed under tension, the plastic film does not hang. This configuration reduces the risk of unwanted hooking of the pallet with a handling machine. Furthermore, the vertical dimensions of the ring can be adapted to the dimensions of the pallet to avoid any unwanted covering of the handling holes.

Particularly advantageously, the plastic film does not cover the handling openings of the pallet. If the pallet orifices are covered, this covering is partial and only on the upper part of the pallet, which reduces the risk of hooking up with handling equipment.

It is particularly advantageous to provide that the height of the cover 3 is configured so as not to obstruct the handling orifices of the support 2, here of the pallet. It is also advantageous to provide that the cover 3 is a heat-shrinkable cover. In this way, during the heat sealing step or in a step to be followed, it is possible to have the retraction of the lower part of the cover 3 which is under the mechanical connection with the fixing zone 4 which allows to reduce the rate of blockage of the handling orifices and the risks of jamming with handling equipment.

In one embodiment, the attachment zone 4 is formed only on the support 2, that is to say that the turn or the turns only face the support in the plane of the turn. The attachment zone 4 is devoid of contact with the load 1. In an alternative embodiment, the attachment zone 4 is formed only on the load 1, that is to say that the turn or the turns only face 'to charge 1 in the plane of the turn. The attachment zone 4 has no contact with the support 2.

In yet another embodiment, it is possible to produce the attachment zone 4 partly on the support 2 and partly on the load 1.

In a particular embodiment, a single attachment zone 4 is produced. In an alternative embodiment, several fixing zones 4 are produced. One or more heat-sealing steps can be carried out in order to fix the cover 3 to the multiple fixing zones 4. By using several fixing zones 4, it is possible to better manage the fixing of the load with the cover 3 and for example better manage the vertical stress that appears after a vertical heat shrink.

During the heat sealing step, it is particularly advantageous to provide that the cover 3 is stretched. Tension can be applied by pulling the cover 3 down.

In a particular embodiment, the attachment zone 4 is formed on the support 2 and / or on the load 1 after the support 2 and the load 1 have been brought into contact. In other words, the support 2 and the load 1 are supplied and the ring forming the fixing zone 4 is installed. In such an embodiment, it is particularly advantageous to produce the ring by means of a wrapping step.

The fixing zone 4 is advantageously made before depositing the cover 3 because this greatly facilitates the production of the fixing zone 4.

In an alternative embodiment, the attachment zone 4 is formed on the support 2 before adding the load 1. It is then possible to prepare the attachment zones 4 on the supports 2 in advance and then to use them for attach the cover 3 to the support 2.

It is also possible to form the attachment zone 4 on the load 1 and then to place the load 1 on the support 2.

If there is only one fixing zone 4 on the load 1, the cover 3 can be configured not to come in front of the support 2.

Of course, when the cover 3 is associated with several attachment zones 4, it is possible to produce certain attachment zones 4 before placing the load 1 on the support 2 and others after contacting.

In a particular embodiment, the method comprises a step of vertical shrinkage of the cover 3. The shrinkage of the cover can be carried out before the heat-sealing step or after the heat-sealing step.

The retraction of the cover 3 makes it possible to reduce the height of the cover 3 and thus apply pressure between the support 2 and the load 1 by means of the cover 3 which is supported on the support 2 via the fixing zone 4.

The cover 3 can be retracted after the cover 3 has been fixed with the fixing zone 4. In this case, the cover 3 can be stretched during heat sealing in order to improve the mechanical strength of the fixing between the cover 3 and the fixing area 4. However, it is also possible not to tension the cover 3.

Alternatively, a partial retraction of the cover 3 can be carried out before sealing the cover 3 with the fixing zone 4 and a partial retraction is carried out after having sealed the cover 3 with the fixing zone 4. Again, it is advantageous stretch the cover 3 before the heat-sealing step, but it is also possible not to stretch the cover 3.

It is also possible to provide for the vertical retraction of the cover 3 to be engaged before heat sealing between the cover 3 and the fixing zone 4. However, in this embodiment, it is particularly advantageous to tension the cover 3 in order to delay the retraction and ensuring the contacting of the fixing zone 4 with the cover 3. This embodiment makes it possible to ensure good mechanical fixing between the cover 3 and the fixing zone 4.

The retraction is advantageously carried out by heating the cover 3 with heating means. This configuration allows the same heating means to be used for shrinking and heat sealing.

When threading the cover 3, it is advantageous to inflate the cover 3 in order to reduce the folds on the cover 3 during the shrinking phase and improve the quality of the heat-sealing.

If shrinkage is done before heat sealing, it may be advantageous to stop inflation just before heat sealing to improve the quality of the heat seal. It is also advantageous to carry out a suction step just before heat sealing in order to facilitate bringing the cover 3 into contact with the fixing zone 4 and thus improve the quality of the contact.

The inflation and aspiration are advantageously carried out by the same ventilation device. According to the direction of rotation, the ventilation device ensures either the inflation of the cover 3, or the suction of air. If the support 2 is not waterproof, it is not necessary to use the air intake unless the load 1 obstructs the evacuation of the air.

The cover 3 can be tensioned by means of a plurality of clamps. Advantageously, the same pliers are used to thread the cover 3 around the load 1 and to put the cover 3 under tension.

The shrinkage and the heat sealing can be obtained by any suitable heating means. Advantageously, the heating means is in the form of a frame which surrounds the cover 3 and which moves vertically in order to be able to heat the entire height of the cover 3. The heating means advantageously sends hot air towards the cover 3 for carrying out the shrinkage and heat sealing, but other techniques can be envisaged such as for example the emission of infrared radiation.

The cover 3 is advantageously a polyethylene house. It is advantageous to produce the fixing zone 4 in polyethylene or in any other material capable of ensuring mechanical fixing with the polyethylene. In general, the cover 3 and the fixing zone 4 are made of materials capable of ensuring heat sealing. In one embodiment, the materials are identical between the cover 3 and the fixing zone 4. Good results have been obtained by using a stretch film to form the ring and a heat-shrinkable film to form the cover.

It is possible to use a heat-shrinkable film to form the ring of the fixing zone 4. If the fixing zone 4 is in the form of a ring before its installation, a first heating step causes the retraction which fixes the ring to load 1 and / or to support 2.

If the film is not heat-shrinkable, for example of stretchable plastic material, it is advantageous to use a fixing zone 4 in the form of a strand to limit the temperature rise in the fixing zone and thus limit the mechanical deformation of the fastening zone under stress.

It is particularly advantageous to produce the turn or turns of the ring in stretchable material instead of a heat-shrinkable material. Indeed, the heat-shrinkable material is thicker than a stretch film and it sticks less well on itself or on other turns of shrinkable material.

Against all expectations, the use of a stretch film to form the ring gives good results because this film was expected to disintegrate when heated. The stretch film is a thinner film than the shrink film which makes it more sensitive to an increase in temperature and in particular during the heat sealing phase. Even if it is known to weld the stretch plastic film to finish a wrapping process, it should be emphasized that the welding step is very localized and is carried out by means of a hot piece which presses on the film to weld and press the film against the pallet.

The use of a strand is particularly advantageous because it makes it possible to limit the rise in temperature by limiting the external surface of the pastic film with respect to its volume. The heating conditions are less restrictive. If the plastic film is a stretch film used in the form of a flat film, then it is advantageous to use a thick film, for example an unstretched film or a weakly stretched film, for example with an absolute stretch ratio less than 100% so as to maintain a substantial thickness and activate the film by stretching to improve its tackiness. Advantageously, the thickness of the stretch film forming the turns is greater than 15 pm and preferably 20 pm.

By pallet is meant a rigid horizontal platform, of minimum height compatible with handling by pallet trucks and / or forklifts or other appropriate equipment. The pallet is used as a support for the gathering, stacking, storage, handling or transport of goods and loads. The pallet is equipped with pallet skids which are spaced from each other to define handling orifices.

Claims (13)

claims 1. A method of covering and heat sealing a cover (3) around a load (1) comprising: - Supply the load (1) arranged on a support (2), - Put the cover (3) on the load (1) by pulling it down so as to come face to a fixing zone (4), - Heat seal the cover (3) with the fixing zone (4), characterized in that the fixing zone (4) is formed by at least one ring of plastic film under stress around the support (2) and / or the load (1) before heat sealing. 2. A method of covering and heat sealing according to the preceding claim wherein the plastic film ring is formed by at least one turn. 3. Method of covering and heat sealing according to one of the preceding claims wherein the plastic film ring comprises at least one flat strip. 4. A method of covering and heat sealing according to one of the preceding claims wherein the plastic film ring comprises at least one strand intended to come into direct contact with the cover. 5. A method of covering and heat sealing according to any one of the preceding claims in which the fixing zone (4) comprises only one or two turns formed by a strand of plastic film. 6. Method of covering and heat sealing according to one of the preceding claims wherein the plastic film ring is formed around the support (2). 7. A method of covering and heat sealing according to the preceding claim, in which the support (2) is a pallet comprising a floor surmounting at least two pallet skids, the ring of plastic film being formed around the floor. 8. A method of covering and heat sealing according to any one of claims 1 to 5 wherein the plastic film ring is formed around the load. 9. A method of covering and heat sealing according to one of claims 1 to 4, 6 to 8 wherein the fixing zone (4) comprises a plurality of turns formed by a strip of plastic film, the consecutive turns overlapping. 10. A method of covering and heat sealing according to any one of the preceding claims in which the cover (3) is stretched during the heat sealing step. 11. A method of covering and heat sealing according to any one of the preceding claims in which the fixing zone (4) is formed after bringing the load (1) into contact with the support (2) and before threading the cover ( 3). 12. A method of covering and heat sealing according to any one of claims 1 to 10 in which the fixing zone (4) is formed before bringing the load (1) into contact with the support (2). 13. Covering and heat sealing device characterized in that it comprises: - a wrapping device configured to deliver a plastic film forming at least one turn around a load (1) or a support (2) 5 supporting the load (1), the at least one turn forming a fixing zone (4), - Means for threading a cover (3) on the load (1) by pulling the cover (3) downwards, the means for threading the cover (3) being configured so that the cover (3) comes facing the zone fixing (4), 10 - heat sealing means configured to heat seal the cover (3) to the fixing zone (4), - a control circuit configured to control the actuation of the heat-sealing means after threading of the cover (3) so that the cover (3) faces the fixing zone (4) during heat-sealing.