FR2719019A1 - A method of packaging a load using a heat-shrinkable sheath and packaging machine implementing such a method. - Google Patents

Abstract

The present invention relates to a method of wrapping a load by heating a heat-shrinkable cover or sheath and to an automatic packaging machine by heating a heat-shrinkable cover or sheath. According to the invention, one ensures, preferably, by blowing the maintenance under the pallet of the lower edge of the sheath during its attachment and prior to the retraction of the sheath at the level of the load. The present invention applies mainly to the overwrapping of palletized loads.

Description

METHOD FOR PACKAGING A LOAD USING A SHEATH

  THERMORETRACTABLE AND PACKING MACHINE

WORKS SUCH A METHOD

  The present invention relates to a method of packaging a load by heating a heat-shrinkable cover or sheath and to an automatic packaging machine by heating a heat-shrinkable cover or sheath. An overpack is usually made of a load, in particular palletized, covering the load with a heat shrinkable sheath that retracts and fits the outer contour of the load

  during a heating step followed by cooling.

  The heating of the heat-shrinkable sheath is typically provided by blowing hot gases, in particular air or combustion gases using a burner, diluted with air. The blast of the hot shrinkage gases can move the sheath, which does not cover the entire load evenly. In addition, the retraction, decreasing not only the perimeter but also the height of the sheath, causes the rise of its lower edge which no longer provides good protection of the lower part of the load. Thus, the Company MSK has proposed in EP-0 133 462 a packaging device comprising a lifting table comprising suction means. The palletized load is lifted from the conveyor giving access to the underside of the pallet. The central aspiration orients the lower edge of the sheath towards the center of the lower face of the pallet during the simultaneous blowing of hot air ensuring the retraction of said lower edge of the sheath. The lift table is then lowered and the

  pallet is rested on the carrier.

  The device of the patent EP-0 133 462 has many disadvantages. The suction lift table is a very complex element. In addition, its operation disrupts the distribution of hot air does not allow a quality retraction of the lower edge of the sheath. The suction ensures a pleating of the lower edge of the sheath towards the center of the lower face of the pallet. The folds, after retraction, form areas of irregular thickness with areas of lower mechanical strength. The pallet is rested on the carrier while the film of the sheath under the underside of the pallet is still hot and therefore fragile. The contact with the carrier deteriorates the film which, before its cooling, is not

  able to support the weight of the palletized load.

  The stability of the load may be compromised by the fact that one raises the pallet by studs arranged under the upper floor of the pallet. It is therefore an object of the present invention to provide a heat-shrinkable sheath completely covering the load of which it

  ensures protection and cohesion.

  It is also an object of the present invention to provide a

  solid sheath, especially in its lower part.

  It is also an object of the present invention to provide a sheath

presenting a beautiful appearance.

  It is also an object of the present invention to provide a

  such sheath employing a small amount of heat-shrinkable film.

  It is also an object of the present invention to provide such a sleeve which does not stick to the load and in particular to a grouping film of

  individual bundles, especially polyethylene.

  It is also an object of the present invention to provide an overpacking method minimizing the risk of dislocation of the pallet

during its handling.

  These objects are achieved according to the invention by ensuring, preferably, by blowing the maintenance under the pallet of the lower edge of the sheath during its attachment and prior to retraction of the sheath at

level of the charge.

  Advantageously, the excess length of the sheath is

  level of the corners of the pallet and / or the edges of the palletised load.

  Advantageously, the cooling film of the heat-shrinkable sheath under the lower face of the pallet is cooled.

  prior to laying it on the conveyor.

  Advantageously, access to the underside of the pallet is obtained by lowering the carrier of the pallet resting on pads of a

table.

  The invention mainly relates to a method of overpacking a palletized load comprising the steps of: a) bringing the load to an overpack station, in particular by a conveyor; b) depositing a heat-shrinkable sheath on at least the lateral faces of the load, the length of the sheath being greater than the height of the palletised load providing a vertical excess length for attachment to a lower face of a pallet supporting the load ; c) clear the underside of the pallet; d) heat-shrinking the vertical excess length of the sheath on the underside of the pallet; e) placing the load on the conveyor; f) heating the remainder of the sheath to ensure shrinkage, characterized in that during step d) of hooking by heat shrinkage of the excess length of the underside of the pallet, it ensures the maintenance of the

  sheath at the vertical faces of the pallet and / or the load.

  The invention also relates to an overpacking process, characterized in that the maintenance of the sheath is ensured without mechanical contact, preferably by blowing cold air by a ramp located above the hot air blowing means ensuring the hooking by heat-shrinking of the vertical excess length on the underside of the

palette.

  The invention also relates to a method, characterized in that it further comprises a traction step on the vertical edges of the sheath in the direction opposite to that of the load, preferably without mechanical contact. The invention also relates to an overpacking process, characterized in that the traction on the edges of the sheath is

performed by suction of air.

  The invention also relates to an overpacking process, characterized in that it further comprises, at the end of step d) 30 of hooking by heat-shrinking of the excess length on the underside of the pallet and before step e) of laying the load on the conveyor, a step g) of cooling the excess length of the sheath under the underside of the pallet improving its mechanical strength and

  avoiding its deterioration during step e).

  The invention also relates to a method, characterized in that the cooling of the excess length of the sheath located under the lower face of the pallet is effected by blowing cold air, preferably from a ramp located under the means for blowing hot air retraction. The invention also relates to a method, characterized in that it comprises, after step b) of depositing a heat-shrinkable sheath on the palletized load, a step h) of smoothing the sheath, preferably by translation from top to bottom on the height of the palletized load of a

  cold air blast ramp substantially surrounding the palletized load.

  The invention also relates to a method, characterized in that in step c) the conveyor is lowered, the pallet resting on a support, preferably a support bearing on the upper floor of the pallet. The invention also relates to a method, characterized in that in step c), the pallet of the conveyor is raised, preferably by means of

  a lifting table resting on the upper floor of the pallet.

  The invention also relates to a palletized pallet loader overpacking machine comprising a conveyor for supplying palletized loads to an overpack station, means for depositing a heat-shrinkable sheath on at least the lateral faces of the palletized load, the length is greater than the height of the palletized load providing a vertical excesslongueur for attachment to a lower face of a pallet, means for disengaging and making accessible the underside of the pallet and heating means of the sheath, including at the level of the excess length, characterized in that it comprises means for maintaining the sheath at the vertical faces of the pallet and / or the load during the hooking by heat-shrinking of the overlength on the underside of the pallet, the means for holding the sheath preferably comprising a cold air blast ramp surrounding the palletized load and

  located above the heating means.

  The invention also relates to a machine, characterized in that it comprises traction means on the vertical edges of the sheath in opposite directions to the load extending over at least a portion of the height of the palletized load, the traction exerted without mechanical contact with the sheath, preferably the traction means comprise vertical suction mouths located near the edges of the

palletised load.

  The invention also relates to a machine, characterized in that it comprises means for cooling the excess length of the sheath hung on the underside of the pallet before contact with the conveyor, in particular a blowing ramp surrounding the load palletized

  and disposed horizontally under the heating means.

  The invention will be better understood by means of the description

  Hereinafter and the accompanying figures given as non-limiting examples and in which: - Figure la is a schematic elevational view of a first overwrapping step according to the invention; - Figure lb is a plan view of the blowing frame implemented according to the present invention; - Figure 2 is a schematic elevational view of a second overpacking step according to the invention; - Figure 3a is a schematic elevational view of a third overpacking step according to the invention; Figure 3b is a plan view of a hot air blower frame used in the present invention; - Figure 4 is a schematic elevational view of a fourth overpacking step according to the invention; - Figure 5 is a schematic elevational view of a fifth overpackage step according to the invention; - Figure 6 is a schematic elevational view of a sixth overwrap step according to the invention; FIG. 7 is a vertical sectional view of a detail of a blow molding frame used in the overpacking apparatus according to FIG.

The present invention.

  In FIGS. 1 to 7, the same references have been used for

designate the same elements.

  The overwrapping machine according to the invention comprises a conveyor 1 for supplying loads 2 resting on a pallet 3 at an overpacking station and known means (not shown) for depositing a heat-shrinkable sheath 4 covering at least the lateral faces (vertical)

  charge and, advantageously, its upper face 5.

  Advantageously, the machine also comprises a thermal insulation bellows reducing the energy consumption and standardizing the temperatures, for example as described in FR-2 564 033. In Figure la, there is shown the palletized load 2 resting on the conveyor 1 for supply and discharge, covered on its face

  upper 5 and on its side faces 6 by a sheath 4 not yet retracted.

  A blowing frame 7 surrounding the load 2, illustrated in more detail in FIG. 7, comprises means 8 for blowing air or hot gas at a temperature, for example, of between 200 and 500 ° C., preferably equal to

  400 ° C and means 9 for blowing cold air (at room temperature).

  Advantageously, the cold air blowing means comprise an upper ramp 9.1 and a lower ramp 9.2. An advantageous distribution of the airflow of the upper boom 9.1 is illustrated in FIG. The air flow is distributed substantially uniformly over the entire width of the side faces 6 except in the corners. On the contrary, the machine according to the invention is advantageously provided with traction means 10 exerting traction on the sheath 4 in opposite directions to the load at its vertical edges. The traction means 10 are, advantageously, without mechanical contact with the sheath, for example suction ramps or means for depositing a first electrostatic charge on the vertical edges of the sheath and electrodes capable of being brought to a temperature.

  second electric charge opposite to the first charge.

  On the contrary, the air flows of the hot air blowing means 8 and the lower ramp 9.2 illustrated in FIG. 3b are distributed substantially uniformly over the entire width of the lateral faces 6 of the

load 2 including in the corners.

  It is advantageous first to smooth the sheath 4 on the load 2 by scrolling from top to bottom, as shown by the arrows 11 in FIG. 1a, the blower frame 7 by blowing cold air with the upper ramp 9.1. Advantageously, traction is simultaneously performed on the vertical edges of the sheath with the means 10. Simultaneously or after the smoothing of the sheath, the lower face of the pallet 3 is disengaged and made accessible. In a first example, as symbolized by the arrow 12 in FIG. 2, the pallet 3 is raised with a lifting table 13. In a second non-illustrated embodiment, the conveyor 1 is lowered, the pallet rests at the initial level of the conveyor on plots based on

its upper floor.

  In FIG. 3a, hot air is blown under the pallet with

  the means 8, which initiates the pulling of the film under the pallet 3.

  Advantageously, it is ensured simultaneously maintaining the sheath by blowing cold air with the upper ramp 9.1 and / or by exerting a

  traction on the vertical edges of the sheath 4 by the traction means 10.

  The traction on the edges of the sheath, advantageously over the entire height of the load 2, makes it possible to tension the sheath at the time of retraction, which avoids the appearance of wrinkles, ensures the grouping of the excess lengths of the films of the sheath. level of the vertical edges of the load 2 and the corners of the underside of the pallet 3, which causes a strengthening of the overpack at the places that are precisely the most exposed and / or most stressed during transport and handling of the load palletized. In addition, this traction combined with the blowing of hot air by the means 8 allows the creation of a space 16 of small thickness, for example equal to 30 mm, to avoid sticking of the hot film of the sheath 4 on the load 2, in particular on a polyethylene film grouping individual packages, such as packs of beverage in cardboard packaging. Space 16 narrows and vanishes during cooling

  and hence the shrinkage of the film of the sheath 4.

  The pallet 3 is lowered, as symbolized by the arrow 14 of FIG. 4, the blower frame 7 being stationary. In the second non-illustrated embodiment, the conveyor 1 rises in the direction of the underside of the pallet. The means 8 are now located at the side faces of the pallet 3, the lower ramp 9.2 is at the level of the conveyor 1. Thus, the upper ramp 9.1 ensures the maintenance of the sheath, the means 8 for blowing hot air ensure the retraction of the sheath 4 at the side faces of the pallet 3. During this time, the portion of the sheath 4 under the pallet 3 has been partially cooled, the retraction is not completed and the film still hot is extremely fragile and

  risk of being damaged when placing the palletised load on the conveyor.

  Thus, it is advantageous to ensure cooling of the film under the pallet 3 before resting the load on the conveyor 1 or to go up the conveyor until the establishment of the context with the underside of the pallet. The cooling of the film of the sheath 4 can be ensured, for example, by cooled shapers or advantageously by cold air blowing by the lower ramp 9. 2, as shown in Figure 5. When the palletized load rests on the conveyor , the sheath 4 being firmly held in its lower part, it stops the cold air blowing by the lower ramps 9.2 and above 9.1. The frame 7 rises, as symbolized by the arrows 15, of Figure 6, by blowing hot air by the means 8 to ensure the retraction of the upper part of the sheath without

  risk of raising the lower part.

  The tensile means 10 are stopped on the edges of the sheath, the hot air blowing is stopped by the means 8 and the frame 7 is raised to a height greater than that of the upper face of the sheath. charge

  palletized. It also goes up a possible bellows of thermal insulation.

  The conveyor 1 ensures the evacuation of the overpacked load and the supply of a new load to be wrapped with which the operations are repeated.

previously described.

  The present invention applies mainly to

  overpacking palletized loads.

Claims (12)

  1. A method of overpacking a palletized load (2) comprising the steps of: a) bringing the load (2) to an overpack station, in particular by a conveyor (1); b) depositing a heat-shrinkable sheath on at least the lateral faces (6) of the load (2), the length of the sheath being greater than the height of the palletised load leaving a vertical excess length for attachment to a lower face of a pallet (3) supporting the load (2); c) disengaging the underside of the pallet (3); d) heat-shrinking the vertical excess length of the sheath (4) on the underside of the pallet (3); e) placing the load on the conveyor (1); f) heating the remainder of the sheath (4) to ensure shrinkage, characterized in that during step d) of hooking by heat shrinkage of the excess length of the underside of the pallet (3), I'on ensures the maintenance of the sheath (4) at the vertical faces of the pallet (3) and / or the load (2).   2. Overpackage method according to claim 1, characterized in that the maintenance of the sheath (4) is provided without mechanical contact, preferably by blowing cold air by a ramp (9.1) above the means (8). ) blowing hot air ensuring the heat shrink hooking of the vertical excess length on the underside of the pallet (3). 3. Method according to claim 1 or 2, characterized in that it comprises, in addition, a traction step on the vertical edges of the sheath in the direction opposite to that of the load (2), preferably without mechanical contact.   4. Overwrapping method according to claim 3, characterized in that the traction on the edges of the sheath (4) is carried out by suction of air.   5. Overpackage method according to any one of   preceding claims, characterized in that it comprises, in addition, at the end   of step d) hooking by heat-shrinking the excess length on the underside of the pallet (3) and before step e) of laying the load on the conveyor (1), a step g) consisting of a cooling the excess length of the sheath under the lower face of the pallet (3) improving its mechanical strength and preventing deterioration in step e). 6. Method according to claim 5, characterized in that the cooling of the excess length of the sheath located under the underside of the pallet is effected by blowing cold air, preferably from a ramp (9.2) located under the means (8) for blowing hot air of retraction.   7. Process according to any one of the claims   preceding, characterized in that it comprises, after step b) of depositing a heat-shrinkable sheath on the palletized load, a step h) of smoothing the sheath (4), preferably by translation up and down on the height of the palletised load (2) of a cold air blower (9.1)   substantially surrounding the palletized load.   8. Process according to any one of claims 1 to 7,   characterized in that in step c) the conveyor (1) is lowered, the pallet (3) resting on a support, preferably a support bearing on the   upper floor of the pallet (31).   9. Process according to any one of claims 1 to 7,   characterized in that in step c) the pallet (3) of the conveyor (1) is raised, preferably by means of a lifting table (13) resting on the floor top of the pallet (3).   10. Palletized load overpacking machine comprising a conveyor (1) for supplying palletized loads to an overpack station, means for depositing a heat-shrinkable sheath (4) on at least the lateral faces (6) of the load palletized (2) whose length is greater than the height of the palletized load providing a vertical excesslength for hanging on a lower face of a pallet (3), means for disengaging and making accessible the underside of the pallet (3) and heating means of the sheath (4), including at the excess length, characterized in that it comprises means for holding the sheath (4) at the vertical faces of the pallet (3) and / or the load (2) during the hooking by heat-shrinking of the excess length on the underside of the pallet (3), the means for holding the sheath (4) preferably comprising a ramp (9.1) blowing cold air surrounding the load   palletized and located above the heating means (8).   11. Machine according to claim 10, characterized in that it comprises traction means on the vertical edges of the sheath (4) in opposite directions to the load (2) extending over at least a portion of the height of the palletised load, the traction exerted without mechanical contact with the sheath (4), preferably the traction means comprise vertical suction mouths located near the edges the palletised load (2).   12. Machine according to claim 8 or 9, characterized in that it comprises means for cooling the excess length of the sheath (4) hooked on the underside of the pallet (3) before contact with the conveyor (1). including a discharge ramp (9.2) surrounding the load   palletized and arranged horizontally under the heating means (8).