EP0088424A1 - Method and device for applying shrink foils to stacks of goods loaded on a pallet - Google Patents

Abstract

In the method, a satchel bag tubular web (23) consisting of shrinkable foil material is pre-opened in the region of its gussets during feeding and then the open side lying to the front in the feed direction is expanded into an opening position larger than the cross- section of a goods stack (11) in each case before pulling up onto the palleted goods stack. Thereafter, the satchel bag tubular web is shrunk onto the goods stack by heat acting on the foil material from the outside. The device possesses a station for receiving the palleted goods stack which has a heating device (42) and means (25, 25', 27, 31) for opening, seizing and expanding the open side of a satchel bag tubular web fed from above by means of a feeding device, the means for seizing and expanding being guided so as to be movable laterally from the goods stack over its entire vertical extension to underneath the bottom edge of the stack. <IMAGE>

Description

The invention relates to a method for applying shrink film to palletized stacks of goods, in which the film material is pulled from above over a stack of goods and then slipped onto the stack by external heat, further to an apparatus for performing such a method _o The application of shrink films to such stacks of goods, which are accommodated on a pallet, is generally known prior art. It is a question of the fact that at one end closed, shrink hood-forming film tubes with their open side facing downwards are pulled in a coating station over a stack of goods in this station and are shrunk under the influence of heat in a subsequent station so that they stack the goods under one enclose certain pre-tension in the cooled state. In the case of the coating station, it is generally the case that, at a certain point, for example a conveyor belt serving to convey such stacks of goods picked up on pallets, the shrink hoods which are closed at one end are pulled by hand over the stacks of goods. The stacks of goods equipped with shrink hoods are then conveyed on to the shrinking station, which is generally a shrinking furnace, in the interior of which a stack of goods covered with a film is received and the shrink film is shrunk onto the stack of goods by heating.

The equipping of palletized goods stacks with shrink films and their shrinking in the above he refined manner is cumbersome and expensive and therefore appears to be in need of improvement. In this respect, the invention has set itself the goal of creating a more cost-effective and easy-to-carry out method for applying shrink films to palletized stacks of goods and the creation of a device which serves to carry out the method.

On the basis of the method explained at the outset, in which the film material is drawn from above over a stack of goods and then shrunk onto the stack by heat from outside, the task set in terms of process technology is achieved in that a side-gusseted tube made of shrinkable film material is fed into the Area of its gussets opened and then before opening the stack of goods, the open front side in the feed direction is spread into an open position that is larger than the cross-section of the stack of goods, and then, immediately after the film tube has been pulled onto the stack of goods, the shrink film is heated and thereby shrunk.

In a departure from the previously known method, in which shrink hoods made of film material are opened by hand on their open side and then pulled by operators from above over a palletized stack of goods, the invention is characterized by the use of a gusseted tube, which in the area of its gussets during feeding So it is forcibly opened, whereupon the open side is spread into an opening position having a larger cross-section than the stack of goods to be covered, which is easy in view of the pre-opening in the area of the side gussets, in order to then pull downwards over the stack of goods to be equipped with a shrink hood and on it subsequently, that is to say, immediately after the film has been pulled on, to be heated and thereby shrunk onto the stack of goods. In contrast to the previously known method, the successive work steps can be carried out in one station.

A particularly economical method is obtained if, according to a design feature, the side gusseted tube is supplied as an endless material and, after the supply of a length section corresponding to the stack height of the stack of goods to be provided with a shrink film, the latter is separated from the endless side gusseted tube becomes. It can be seen that a method designed according to this feature is particularly suitable for being integrated into the work cycle of a packing line.

To the extent that equipping a palletized stack of goods with shrink films serves the purpose of ensuring the cohesion of the goods stacked on a pallet, it is quite sufficient to use length sections of a film tube made of shrinkable material corresponding to the stack height. If, on the other hand, such a shrink film is intended to provide a degree of protection against environmental influences, for example against dust and / or moisture, beyond the cohesion of the goods picked up on a pallet, it has proven to be advantageous according to a further embodiment of the method according to the invention if Feeding a length section corresponding to the stack height, this is provided with a transverse weld at its rear end in the feed direction and then separated from the endless side-gusseted hose behind this transverse weld, so that it is closed at its top end in the feed direction by the transverse weld lying in front of the separating cut Shrink hoods are created which, after opening and shrinking, also span the upper end of a palletized stack of goods.

When shrinking a shrink film drawn over a stack of goods in the manner explained above, it is important to heat the shrink film spanning the stack of goods evenly on at least two sides apart from one another, so as to shrink the film as uniformly as possible when the thermoplastic film material cools to secure the stack of goods. As a rule, uniform heating of the shrink film should be aimed for on all sides. According to a further design feature of the method according to the invention, it has proven to be particularly advantageous to heat the shrink film progressively from bottom to top after pulling on the side-gusseted tube and thereby shrinking it onto the stack of goods in such a way that initially over the bottom edge of the Sections of the shrink film protruding from the stack of goods are shrunk on and the shrinking process then continues gradually upwards to the top edge of the stack of goods. This ensures that the over the lower edge of the film When shrinking, first stack the drawn film sections around the bottom edge of the stack so that pulling up these sections over the bottom edge of the stack is prevented due to the shrinkage of film sections in the area of the stack side walls. Insofar as shrink films of this type are intended to achieve or at least improve the cohesion of palletized stacks of goods, it is important that the shrink film wraps around the lower edge of the entire stack in order to ensure a secure connection between the goods stacked on a pallet and the pallet.

In terms of device technology, the object of the invention is achieved in that, in a station receiving the palletized stack of goods, a heating device acting on the walls of the stack of goods from the outside and means for opening, detecting and spreading the open side of a side gusseted tube made of shrinkable film material fed from above by means of a feed device are provided are, and that the means for grasping and spreading the gusseted tube are guided laterally from the stack of goods over its entire vertical extent to below the bottom edge of the stack, around which at its in Pull the open front side of the open and spread side gusseted hose over the stack of goods.

A device designed in this way, which makes it possible to implement the above-mentioned method in its basic form, therefore enables this method to be incorporated into the work cycle of a packing line without problems.

An embodiment of this device is characterized in that the feed device for the side gusseted tube has two conveyor rollers that receive it between them, rotating in opposite directions, and that two lateral opening wedges are provided as means for opening the open side of the side gusseted tube in the feed direction behind these rollers, which are provided in the side gussets of the Insert the film tube and spread it apart as it is fed to the station. It is, of course, to be assumed that the side gusset hose with flat sides abutting one another and along the two side edges which are spaced apart from one another will be passed between the side folds folded between the flat sides between the conveyor rollers of the feed device.

If a gusseted hose in the form of continuous material is used according to one of the designing process features, it is also necessary according to a likewise designing feature of the device that a cutting device is provided for separating predetermined length sections from the continuously supplied gusseted hose, which means that a parallel to the axes of rotation of the conveyor rollers of the Feeder has reciprocally guided knife. A device designed in this way can also be characterized by a welding device with welding jaws running parallel to the axes of rotation of the conveying rollers, if shrink hoods closed at the top are to be used, around the respective rear end of a predetermined length section of the film tube before the separation from the continuous material with a transverse weld seam complete.

A further embodiment of the device according to the invention is characterized in that as means for grasping and spreading the open side of the corrugated tube four from below into the area of the side folds Serve pre-opened hose and then swivel into their spreading positions, which can be pivoted to a frame that grips around a stack of goods received in the station and between a position that detects and spreads the open side of the supplied film tube over the palletized stack of goods and one this open side is guided to be vertically movable up to the position under the bottom edge of the stack.

With regard to the design of the heating device, various configurations are also conceivable if the thermal effect on the shrink film drawn over the stack of goods should begin in the region of the film ends reaching over the lower edge of the stack of goods and should continue to progress upwards. A sensible embodiment, however, is characterized in that the heating device comprises movable heat sources at a distance from the side walls of the palletized stack of goods over the entire stack height and below the bottom edge of the stack, which can be arranged on a frame which encompasses the stack of goods received in the station and between a position is vertically movable under the lower edge of the stack of goods up to a position reaching to the top of the stack.

Although a wide variety of heating sources are conceivable for applying the heat required for the shrinking process to the shrink film drawn over a stack of goods, it has proven expedient to use gas burners which are directed toward the walls of the stack of goods received in the station.

According to a design feature of the invention, it has proven to be advantageous to arrange the heating device above the grippers, by means of which the open side of the gusseted tube is gripped and opened and the gusseted tube is pulled from above over a stack of goods received in the station. With such a design of the device, it is possible to keep the open side of the side gusseted tube in a position protruding beyond the lower edge of the stack of goods until this region of the opened side gusseted tube is shrunk onto the stack of goods as a result of thermal action from outside.

• Fig. 1 eine Vorrichtung zum Auftringen einer Schrumpffolie auf einen palettierten Güterstapel während des Aufziehens eines Seitenfaltenschlauchs auf den Güterstapel mittels in die Offenseite des Seitenfaltenschlauchs eingreinfender und diesen aufspreizender Greifer, in einer seitlichen Ansicht,
• Fig. 2 bei Weglassung der Zuführeinrichtung für den Seitenfaltenschlauch die Vorrichtung in einer Ansicht wie in Fig. 1, jedoch mit einem bereits mit einer Schrumpfhaube ausgerüsteten Güterstapel während des Aufschrumpfens dieser Schrumpfhaube und
• Fig. 3 in einer Ansicht gemäß Pfeil III in Fig. 1 die Offenseite des im Bereich der Seitenfalten vorgeöffneten Folienschlauchs mit den von unten eingreifenden Greifern zum Aufspreizen der Offenseite des Folienschlauchs.

An embodiment of the device according to the invention is illustrated in the accompanying drawing and will be explained below with regard to its structure and its mode of operation. Schematic views show:

• 1 shows a device for applying a shrink film to a palletized stack of goods while pulling up a side gusseted hose onto the stack of goods by means of a gripper that grips into the open side of the side gusseted hose and expands it, in a side view,
• Fig. 2 with omission of the feed device for the gusseted hose, the device in a view as in Fig. 1, but with a stack of goods already equipped with a shrink hood during the shrinking of this shrink hood and
• Fig. 3 in a view according to arrow III in Fig. 1, the open side of the film tube pre-opened in the area of the side gussets with the grippers engaging from below for spreading the open side of the film tube.

In the device 10, which is best seen in its entirety from FIG. 1, the palletized goods stacks, which are designated in their entirety by 11 and are constructed on a pallet 12 in a palletizer (not illustrated further), by means of an indicated roller conveyor 13 according to arrow 14 into one summarized pulling and shrinking station 15 of the device introduced. This pulling-over and shrinking station is located within a tower-like frame 16, which consists of four vertically running columns 17 which delimit a rectangular cross-section and which are connected to one another at their upper ends via supports 18. The roller conveyor 13 for conveying the palletized stacks of goods 11 extends across this frame-like frame 16 and also serves to remove the stacks of goods from said station after pulling on and shrinking on a shrink film. In the area of the station, the roller conveyor is equipped with lifting means (not shown) which, after a palletized goods stack 11 has been fed in the correct position, move up between the conveyor rollers of the roller conveyor and thereby fix the palletized goods stack in its correct position in the station, as shown in FIG. 1.

In the area of the upper straps 18 connecting the pillars 17 of the frame 16 surrounding the station 15, a boom 20 extends with two supports running parallel to one another, between which a supply roll 22 with film material 23 in the form of a gusseted tube rotatable about a horizontal axis 21 is received is. The cross section of this gusseted tube is dimensioned such that this gusseted tube can be pulled over the palletized goods stack 11 in the spread state without any problems.

The film tube 23 drawn off from the supply roll 22 is first fed approximately horizontally above the pulling-over and shrinking station 15 and there deflected vertically downward via a deflection roller 24, the turning axis of which runs parallel to the axis of rotation 21 of the supply roll. The means for feeding the film tube to the station 15 are initially two conveyor rollers 25, 25 'rotating in opposite directions below the top chords 18 of the frame 16, the axes of rotation of which likewise extend parallel to the axes of rotation of the deflecting roller 24 and the supply roller 22 and that of the station Take hose material 23 to be supplied between them in such a way that the side folds of the hose material lie in the region of the side edges which are distant from one another. The direction of rotation of the conveyor rollers when feeding the film tube 23 to the station is shown by the arrows 26, 26 '. In the region of these side folds of the hose material, opening wedges 27 are arranged which face the feed direction, the wedge tips of which point upwards and which engage in the side folds when the hose material is supplied. Accordingly, an open side of a supplied side-gusseted tube lying in the area of the opening wedges 27 is pre-opened in the manner shown in FIG. 3, and it is thus possible to insert four grippers 31 arranged on a frame 30 vertically movable within the frame 16 from below into the open side 32 of the supplied side-gusseted tube 23 to introduce. After the insertion of the grippers, as shown by the arrows 33, 33 'in FIG. 3, they are spread apart, the open side of the gusseted tube being brought into the opening position 28 indicated by dash-dotted lines in FIG corresponds to the cross-sectional shape of the palletized stack of goods, but is larger than its cross-section.

After the open side 32 of the supplied film tube has been grasped and spread open, the grippers 31 received on the frame 30, which is vertically movable within the frame 16 of the device, move downward from the position indicated by the dashed lines in FIG is indicated schematically in the drawing at 36, the gusseted tube with its open side from above over the palletized goods stack 12 received in the station. As soon as a length section sufficient for the shrink film to be applied has been pulled through, the grippers 31 are stopped in their downward movement and below the Opening wedges 27 arranged welding jaws 38, 38 ', which extend parallel to the conveyor rollers 25, 25', move together and form a transverse welding seam 39 which closes the upper end of this length section of the gusseted tube and which can be seen in the finished shrink hood 40 in FIG. 2. After this transverse welding, a cutting device, not shown, with a conveyor parallel to the axes of rotation Roll-guided knife triggers, which separates the length section of the gusseted tube, which is closed at its rear end in the feed direction by means of the transverse weld, from the endlessly fed film material 23. The conveyor rollers 25, 25 ', which are stopped when the grippers 31 guided on the frame surrounding the station stop, then remain in the rest position, while the grippers 31 are moved vertically downward into a position which extends below the lower edge of the palletized goods stack received in the station 15 11 is enough. The shrink film that is drawn over the stack of goods by means of the grippers therefore extends to below the lower edge of the stack of goods after being pulled up.

Furthermore, a vertically movable heating device 42 is provided in the frame 16 enclosing the station 15, which consists of a frame 43 guided in the frame, enclosing the stack of goods 11 received in the station, and gas burners 44 arranged thereon, which are directed towards the side walls of the stack of goods are. This heating device corresponds to the downward movement of the grippers 31 when the film tube is pulled over the one in the station move the stack of goods received into a lower position, in which the burners 44 are ignited as soon as the side gusseted hose with its downward-facing open side is drawn onto the stack of goods above the lower edge thereof. As a result of the ignition of these gas burners, the sections of the gusseted tube consisting of shrinkable film material which extend beyond the lower edge of the stack of goods are first heated and shrunk in such a way that these sections partially wrap around the lower edge of the stack of goods and thereby establish a firm connection between the shrink hoods and the produce the pallet 12 receiving the goods. After shrinking on these lower sections of the shrink hood 40, the heating device 42 moves upwards at a speed corresponding to the requirements of the shrinking process, as the arrow 45 in FIG. 2 indicates. The film material of the shrink hood 40 is gradually shrunk onto the palletized stack of goods, progressively from bottom to top.

Corresponding to the upward movement of the heating device 42, the grippers 31 move upwards in order to finally to be pivoted in a position above the stack of goods 11 provided with a shrink hood 40 in the station 15 against the directions indicated by the arrows 33, 33 'in FIG. 3 and to engage in the downward-facing open side of the next hose material fed from the roll . This completes the opening and shrinking of a shrink hood onto a palletized stack of goods and operational readiness for the next palletized stack of goods in the work step, which is introduced into the winding and shrinking station after the previous stack of goods has been removed from the station according to arrow 46.

A method and a device for fully mechanized drawing and shrinking of shrink films onto palletized goods stacks are thus created, the drawing and shrinking being realized in two immediately successive working steps within a station.

Claims (14)

_1st Method for applying shrink films to palletized stacks of goods, in which the film material is pulled over a stack of goods from above and then shrunk onto the stack by external heat, characterized in that a gusseted tube (23) made of shrinkable film material is fed in the area of the stack Side gussets opened and then each before opening onto the palletized stack of goods (11) the open front side (32) in the feed direction is spread into an open position that is larger than the cross section of the stack of goods, and then immediately after being pulled onto the stack of goods , the shrink film is heated and shrunk as a result. 2. The method according to claim 1, characterized in that the gusseted tube (23) is supplied as an endless material and after feeding a length of the stack of goods to be provided with the shrink film (11) corresponding length section of the latter is separated from the endless gusseted tube. 3. The method according to claim 2, characterized in that after feeding a length section corresponding to the stack height, this is provided at its rear end in the feed direction with a transverse weld (39) and then separated from the endless side gusseted hose (23) behind the latter. 4. The method according to any one of claims 1 to 3, characterized in that after pulling on the gusseted tube on the stack of goods (11), the shrink film progressively heated from the bottom up and is thereby shrunk onto the stack of goods. 5. Device for performing one of the methods according to claims 1 to 4, characterized in that in a the palletized stack of goods (11) receiving station (15) from the outside acting on the walls of the stack of goods heating device (42) and means (25, 25 ', 27, 31) for opening, grasping and spreading the open side (32) one is provided by means of a feed device from above side gusseted hose (23) made of shrinkable film material, and that the means (31) for grasping and spreading the side gusseted hose are guided laterally from the stack of goods over its entire vertical extent to below the bottom edge of the stack, around which on its open side spread and grasped side gusseted hose over the stack of goods. 6. The device according to claim 5, characterized in that the feed device for the gusseted tube (23) has two these between-n receiving, oppositely rotating conveyor rollers (25, 25 ') and that as a means for opening the open side of the gusseted tube in the feed direction behind these rollers are followed by two lateral opening wedges (27) which engage in the side folds of the film tube and spread them apart as they are fed to the station (15). ₇ . Apparatus according to claim 6, characterized in that a cutting device is provided with a knife guided parallel to the axes of rotation of the conveyor rollers (25, 25 ') of the feed device for separating predetermined length sections from a gusseted tube (23) fed as continuous material. 8. The device according to claim 7, characterized by a welding device (42) with parallel to the axes of rotation of the conveyor rollers (25,25 ') welding jaws (38,38') to the respective rear end of a predetermined length of the film tube before the separation of complete the continuous material with a cross weld (39). 9. Device according to one of claims 6 to 8, characterized in that as a means for detecting and spreading the open side (32) of the gusseted tube (23) four engaging from below in the pre-opened in the region of the gusseted tube and then pivotable into their spreading grips (31) serve. 10. The device according to claim 9, characterized in that the grippers (31) are pivotally articulated on a frame (30) which engages around a stack of goods (11) received in the station (15) at a distance and between one the open side of the supplied film tube is guided over the palletized stack of goods in a spreading position and a position which pulls this open side vertically up to below the bottom edge of the stack. 11. The device according to one of claims 3 to 10, characterized in that the heating device (42) at a distance from the side walls of the palletized goods stack (11) over the entire stack height and up to the bottom of the stack comprises movable heating sources (44). i 12. The apparatus according to claim 11, characterized in that the heating sources (44) are arranged on a frame (43) which engages around the stack of goods (11) received in the station (15) and between a position below the lower edge of the stack of goods up to a position reaching to the upper edge of the stapä is vertically movable. ₁₃ . Apparatus according to claim 11 or 12, characterized in that the heating sources are gas burners (44) directed towards the walls of the stack of goods (11) accommodated in the station (15). 14. Device according to one of claims 11 to 13, characterized in that the heating device is arranged above the grippers (31) for grasping and opening the open side (32) of the gusseted tube.

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