DEVICE AND METHOD FOR SHRINKING A SHRINK FILM ONTO A STACK OF GOODS

Abstract

The invention relates to a device for shrinking a shrink film (1) onto a stack of goods (2), wherein a shrink frame (3) is provided, which can be moved on the stack of goods and which surrounds the stack of goods while the shrink film is shrunk on. The shrink frame has a plurality of heating apparatuses distributed over the perimeter of the shrink frame for heating the shrink film for the shrinking process. Furthermore, there is a cover plate (6) that covers the stack of goods and that is arranged in particular at a distance from the top side (7) of the stack of goods during the shrinking process. Side walls (11) extending along the stack of goods are provided between the shrink frame and the cover plate, and intermediate spaces for the heated gases flowing upward are formed between the stack of goods and the side walls. The cover plate can be moved toward the top side of the stack of goods and can be moved away from the top side of the stack of goods. The side walls form a frame, in particular a rigid frame, and the cover plate can be moved within said frame.

Description

The invention relates to an apparatus for shrink-fitting a film onto a stack of objects with a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during shrink-fitting of the shrink film. The invention further relates to a method for shrink-fitting a film onto a stack of objects.

The term “stack of objects” refers in particular to a plurality of packages, parcels, bags, or units of this kind that are advantageously stacked in a parallepipedal stack of objects. It is within the scope of the invention that the stack of objects is carried on a pallet. However, stacks of objects without a pallet can also be used. Basically, the stack of objects can also consist of a few stacked objects, or a single larger unit, for example, from the white objects sector (washers, refrigerators, dishwashers and the like. It is further within the scope of the invention, that the film is a film made of plastic that can be shrunk onto the stack of objects under the influence of heat. In this way, the units stacked in the stack of objects are firmly held together and in particular, are secured against slipping and the like. The film can be placed onto the stack of objects in the form of a package band, or can be pulled over the stack of objects in the form of a tube or a hood. Subsequently, the shrink-fitting of the film takes place under the action of heat.

There are shrink frames known in the art that surround the stack of objects and are displaced vertically along the stack of objects, and thereby heat the film according to the vertical position of the shrink frame. The heating is done by way of heaters or burners distributed around the periphery of the shrink frame that are electrically or gas powered. The thermal energy released to the film can be controlled corresponding to the spacing of the burner from the stack of objects and by controlling the energy output of the burners and the vertical speed of the shrink frame.

If stacks of objects having greater differences with regard to their dimensions (for example, 500 mm×500 mm to 1800 mm×1800 mm) are processed successively, several shrink frames of different dimensions can be held ready on the one hand, and for the shrinking process, the shrink frame that comes closest to the corresponding dimensions of the stack of objects is the one selected. Although essentially shrink frames have proven their worth, such devices are voluminous and costly. On the other hand, shrink frames with movable shrink strips can also be used to adapt the spacing of the burners to the respective dimensions of the stack of objects. However, this type of method is relatively complex because in the case of a size reduction of the shrink frame, the burners have to be turned off segmentally, and because many mobile components are used. This is primarily a problem if the components are gas fired.

Furthermore, closed shrink ovens are known in the art where the film is usually shrunk onto the stack of objects with the aid of a circulating air system for heat distribution. However, these shrink ovens have the considerable disadvantage that the targeted heat supply for an optimal shrink-fitting of the film onto the different areas of the stack of objects is not possible. In contrast thereto, the shrink frames have proven to be significantly more effective.

The object of the invention to further improve the already existing efficiency of a shrink frame, and in particular, to provide an energy-saving apparatus and an energy-saving method for shrinking-fitting a film.

This object is attained in an apparatus for shrink-fitting a film onto a stack of objects where a shrink frame is provided that can be moved over the stack of objects and that surrounds the stack of objects during the shrinking-fitting of the film, wherein

• • the shrink frame is provided with a plurality of heaters distributed around its periphery for heating the shrink film during the shrinking process,
  • furthermore, a cover plate covering the stack of objects is provided that in particular is spaced from a top face of the stack of objects during the shrinking process,
  • below the cover plate, side walls are provided extending along the stack of objects, or along the side faces of the stack of objects, and
  • between the stack of objects, or between the side faces of the stack of objects and the side walls, clearances for the heated gases flowing to the cover plate, or flowing upward, are formed,
  • the cover plate can be moved to the top face of the stack of objects and can be moved away from the top face of the stack of objects, and
  • the side walls form a frame, in particular a rigid frame, within which the cover plate can move.

It is within the scope of the invention that the cover plate can be displaced vertically to the top face of the stack of objects and vertically away from the top face of the stack of objects. Advantageously, the cover plate can be displaced vertically in the frame with little play with respect to the side walls. According to a recommended embodiment, the gap between the cover plate and side walls is sealed by at least one sealing element or by at least one flexible sealing element.

According to an embodiment of the invention, rigid side walls form a rigid frame that is open upward toward the cover plate, and the cover plate can be moved vertically within the frame or between side walls of the frame. It is within the scope of the invention that with a lower end of the rigid frame is fastened to the shrink frame. With a parallepipedal stack of objects, the rigid frame is advantageously formed as a cubic box that is open at the top. The cover plate can then telescope into the frame or the cuboidal box.

A particularly preferred embodiment of the invention is characterized in that the frame, in particular the rigid frame, can be suspended from the cover plate, and that when thus suspended the frame can be moved with the cover plate. During displacement of the cover plate, the suspended frame is entrained by the cover plate. The cover plate and the side walls are then joined together to form a box, and this box moves as a whole over the stack of objects. Advantageously, the side walls or the frame with upper cover segments are combined to form a box, and in the suspended state of the frame or the box from the cover plate, the cover segments rest on the cover plate. According to an especially recommended embodiment, a first partial frame or box, and a second partial frame or box are provided, the first partial frame or box, engages, or can engage, in the second partial frame or box, and the cover plate in the first partial frame or box, and/or in the second partial frame or box, can be moved toward the stack of objects, or away from the stack of objects. Based on this displaceability of the cover plate, the height of the space V between the cover plate and stack of objects is adjusted. According to this embodiment, the first partial box forms an inner box so to speak and the second partial box forms an outer box, and these two partial boxes are configured to telescope. According to one embodiment, the first partial box and the second partial box are of the same height. The first partial box can engage completely or partially within the second partial box. It is within the scope of the invention that the second partial box can be moved downward, or vertically downward so that the first partial box projects from the second partial box at least partially. Preferably, the second partial box is fixed by its lower end to the shrink frame. It is recommended that the second partial box can be moved with the shrink frame, particularly downward, or vertically downward.

In order to solve the technical problem, the invention further teaches an apparatus for shrink-fitting a film onto a stack of objects with a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during the shrinking-fitting of the film, wherein

the shrink frame is provided with a plurality of heaters distributed around its periphery for heating the film during the shrinking process,

furthermore, a cover plate covering the stack of objects is provided that in particular is spaced from a top face of the stack of objects during the shrinking process,

below the cover plate, side walls are provided extending along the stack of objects or along side faces of the stack of objects, and clearances are formed between the stack of objects or the side faces of the stack of objects and the side walls, for the heated gases flowing to the cover plate, or flowing upward, and

the side walls are made of a flexible material so that during upward movement of the shrink frame, they can be rolled off winders on the cover plate, in accordance with the progression of the downward movement of the shrink frame.

It is within the scope of the invention that with movement of the shrink frame in the opposite direction, the flexible side walls can also be rolled up again. In this embodiment, the side walls are advantageously made of a fire-proof, or heat-resistant flexible material. It is recommended that the winders are connected to or fixed on the top face of the cover plate facing away from the stack of objects. The space between the cover plate and top face of the stack of objects can be easily adjusted, subject to the progression of the shrink progress and to the height of the stack of objects.

To attain the object, the invention further teaches an apparatus for shrink-fitting a film onto a stack of objects with a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during the shrink-fitting of the film, wherein

the shrink frame is provided with a plurality of heaters distributed around its periphery for heating the film during the shrinking process,

furthermore, a cover plate covering the stack of objects is provided that in particular is spaced from the top face of the stack of objects during the shrinking process,

below the cover plate, side walls are provided extending along the stack of objects, or along the side faces of the stack of objects, and wherein between the stack of objects, or between the side faces of the stack of objects and the side walls, clearances are formed for the heated gases flowing to the cover plate, or flowing upward, and

the inner shell formed by the side walls and the cover plate is enclosed by an outer shell with upper outer plate and outer side walls such that the heated gases emerging from the cover plate can flow into the clearances formed between the inner shell and the outer shell to the shrink frame, or particularly, vertically downward to the shrink frame.

In this embodiment, energy savings are achieved on the one hand in that the heated gases flowing through the clearances between the side walls and the stack of objects as well as through the space between the cover plate and the top face of the stack of objects can effectively preheat the film for the shrinking process. On the other hand, the heat escaping with the heated gases from the cover plate is recirculated to the shrink frame and thus, excess heat is utilized to further reduce energy consumption. As a result of the recirculation of the heated gases, the output of the heaters, or the burners of the shrink frame can be further reduced, that is to say, correspondingly to the temperature of the recirculated heated gases, or the recirculated heated air. Preferably, recirculation of the heated gases is assisted by at least one blower in the cover plate. Advantageously, the outer shell is fastened to the shrink frame. According to an embodiment of the invention, both the side walls of the inner shell and the outer side walls of the outer shell are flexible and preferably as fire-proof, or heat-resistant walls. It is then possible that with the aid of winders, both the flexible side walls and the flexible outer side walls can be rolled off the winders, or onto the winders, with corresponding movements of the components. In this way, the height of the space above the stack of objects can be adjusted in accordance with the shrink progression and the height of the stack of objects. However, the inner shell and/or the outer shell can also be provided with rigid side walls/outer side walls and preferably, the cover plate can then be vertically moved in the rigid frame from the rigid side walls. If need be, the inner shell and/or the outer shell can also be cooled.

A special embodiment of the invention is characterized in that the side walls of the inner shell and/or the side walls of the outer shell are designed in a bellows-like manner. The inner shell and/or the outer shell can then be folded in the form of a sleeve in the manner of a concertina if the cover plate, or the upper outer plate is displaced vertically downward, or toward the top face of the stack of objects. On the other hand, the inner shell and/or the outer shell can be unfolded in the manner of a concertina if the cover plate, or the upper outer plate is moved in the opposite direction. It is within the scope of the invention that with this embodiment, the cover plate can also be moved to the top face of the stack of objects and away from the top face of the stack of objects.

The following specifications and the preferred embodiments described therebelow apply to all above-described embodiment variations of the apparatus according to the invention. According to a particularly preferred embodiment of the invention, the cover plate covering the stack of objects is provided with at least one outlet port for releasing heat generated during the shrinking process, or for releasing heated gases generated during the shrinking process, in particular heated air. In principle, the at least one outlet port or the at least one upper outlet port could also be provided in the upper area of a side wall. It is within the scope of the invention that the outlet port can be closed by a closing element, for example, a throttle valve. However, in principle, the invention could also be used entirely without outlet port, or upper outlet port.

The invention is based on the realization that with the apparatus according to the invention, an effective preheating of the film adhering to the side faces of the stack of objects, and also a film segment located on the top face of the stack of objects is possible. It is within the scope of the invention that during the shrinking process, the shrink frame is moved from a lower area of the stack of objects or the pallet toward the top face of the stack of objects. Due to the preheated film segments at the side faces and/or on the top face of the stack of objects according to the invention, the output of the heaters or the burners can be reduced and in this way energy can be effectively saved. According to the invention, the heaters or the burners can be readjusted subject to extend of the preheating of the film segments by the heated gases. The heaters are preferably burners that are powered by electricity or gas. According to a particularly preferred embodiment of the invention, a shrink frame with electric heating according to EP 0 386 530 1 [U.S. Pat. No. 5,511,528] is used. It is within the scope of the invention that the film is a film made of plastic that is capable of shrinking if subjected to heat.

It is recommended that the side walls are provided between the shrink frame and the cover plate. Advantageously, the side walls spaced from the side faces of the stack of objects form a closed shell that completely encloses the side faces of the stack of objects. It is within the scope of the invention that a parallepipedal stack of objects is provided with the shrink foil. Preferably, four side walls are then provided that are cubically arranged with rectangular or square cross-sections. It is recommended that the side walls project above the top face of the stack of objects. It is preferred that at least in the operating state during the shrink-fitting of the film, the side walls project upward to the cover plate. It is advantageous that the side walls are made of a heat-resistant, or fire-proof material. According to a particularly preferred embodiment of the invention, the side walls, or the lower ends of the side walls are fixed to the shrink frame.

It is recommended that the cover plate projects above the edges, or rims of the top face of the stack of objects. Preferably, the cover plate is parallel, or essentially parallel, to the top face of the stack of objects. It is within the scope of the invention that at least during shrink-fitting of the film onto the side faces of the stack of objects, the cover plate is spaced from the top face of the stack of objects.

It is further within the scope of the invention that the cover plate can be moved vertically toward the top face of the stack of objects and vertically away from the top face of the stack of objects. It is recommended that the cover plate can be displaced relative to the side walls. Advantageously, the side walls are not moved along during displacement of the cover plate. By moving the cover plate toward the top face of the stack of objects, a space reduction between the top face of the stack of objects and the cover plate can be realized that allows an effective preheating of the film by the heated gases rising upward so that the output of the heaters of the shrink frame can be reduced. If, according to one embodiment, the side faces of the stack of objects are covered by a film tube or a film strip, and if a top sheet film rests on the top face of the stack of objects, the cover plate can also be moved, or pressed, onto the top face of the stack of objects in order to bond together the film tube or the film banderole and the top sheet film. According to a variation of an embodiment of the invention, the cover plate is provided with a coating, particularly a Teflon coating, on its lower side facing the top face of the stack of objects. In this way, sticking of the top sheet film to the cover plate can be avoided when the cover plate is pressed onto the top face of the stack of objects.

According to a particularly preferred embodiment of the invention, at least one blower is located on or in the cover plate and can extract the heated gases by suction or suck them in or with which cold gas or cold air can be fed in. It is within the scope of the invention that the at least one blower is in the area of or on the at least one outlet port. It is advantageous that the at least one blower is reversible so that the heated gases can be either removed by suction, or cool gas can be supplied if there is need for cooling. This is particularly the case if the temperature of the heated gases is or becomes too high in the area between the cover plate and the top face of the stack of objects, and/or in the area between the side walls and the side faces of the stack of objects. In principle, a cooler can also be provided on the cover plate or be present in addition thereto.

It is within the scope of the invention that the cover plate can be displaced or moved independently of the displaceability of the shrink frame. In principle, during downward movement of the shrink frame in its operational position, for example, the cover plate can be moved downward parallel with the shrink frame. Particularly for reducing or increasing the space between the cover plate and top face of the stack of objects, the cover plate can be moved, or vertically displaced entirely separately from the shrink frame according to a preferred embodiment of the invention.

In order to attain the object, the invention also teaches a method for shrink-fitting a film onto a stack of objects, the film being shrink-fitted onto the stack of objects with a shrink frame with for this purpose the shrink frame surrounding the stack of objects and being vertically moved along the stack of objects such that the film is heated for the shrink-fitting by a plurality of heaters distributed around the periphery of the shrink frame, wherein

a cover plate above the stack of objects is moved vertically toward the stack of objects or vertically away from the stack of objects for adjusting a space between the cover plate and stack of objects,

heated gases generated during the shrinking process flow through clearances that are formed between the stack of objects, and in particular the shrink frame, and side walls or vertical side walls extending to the cover plate are formed, the heated gases being extracted, preferably by suction, and

during displacement toward the stack of objects and during displacement in the opposite direction, the cover plate is moved in a frame or a rigid frame formed by side walls or rigid side walls.

In order to attain the object, the invention further teaches a method according to patent claim 15 and a method according to patent claim 16.

It is within the scope of the invention that the shrink frame is moved at least up to the lower side of the stack of objects, and subsequently during operation of the heaters for heating and for shrink-fitting the film is moved toward the top face of the stack of objects. If the stack of objects is on a pallet, the shrink frame can also be moved to the pallet or under the pallet, in order to realize a corresponding bottom shrinkage.

It is further within the scope of the invention that the heat output of the heaters is reduced, or ramped down if the film is heated on the side faces of the stack of objects by the heated gases flowing by or flowing to the cover plate to a degree that contributes to the shrink-fitting. Advantageously, the shrinking process is controlled by regulating the suction power of the at least one blower in the cover plate, and by controlling the output of the heaters of the shrink frame. If during the shrinking process the temperature increases in the area above the shrink frame, the output of the heaters is reduced when moving across this area, because the film is already preheated there. Thus, the energy required for the shrinking process can be correspondingly reduced.

The invention is based on the realization that with the apparatus according to the invention and with the method according to the invention, a surprisingly high amount of energy can be saved during the shrinking process. To this extent, the effectiveness of an already substantially more efficient shrink frame as compared to shrink ovens can still be significantly increased. The apparatus according to the invention and the method according to the invention can also be realized with relatively simple and low-cost measures. Basically, already existing apparatuses can be retrofitted with the system of the invention in a relatively simple way. All in all, the invention is characterized by relatively low cost and low expenditure. It should also be pointed out that an apparatus according to the invention has a relatively small construction volume.

The invention is described in more detail below with reference to a drawing illustrating only one embodiment. In the schematic drawing:

FIG. 1 is a side view of an apparatus according to the invention in a first embodiment,

FIG. 2 shows another embodiment of the apparatus according to the invention in a first functional position,

FIG. 3 shows the apparatus of FIG. 2 in a second functional position,

FIG. 4 shows the apparatus of FIG. 3 in a third functional position,

FIG. 5 shows the apparatus of FIG. 2 in cross-section in a further functional position with a short stack of objects,

FIG. 6 shows another embodiment of the apparatus of FIG. 1,

FIG. 7 shows another embodiment of the apparatus of FIG. 1, and

FIG. 8 shows another embodiment of the apparatus of FIG. 1.

The figures show an apparatus for shrink-fitting a film 1 onto a stack 2 of objects with a shrink frame 3 that is displaceable over the stack 2 of objects and that surrounds the stack 2 of objects during the shrink-fitting of the film. In the embodiment according to the figures, the shrink frame 3 is provided with a plurality of heaters 4 distributed around its periphery for heating the film 1 for the shrinking process. In the illustrated embodiment, the heaters are gas-powered burners 5. However, electrically operated heaters can also be used.

According to the invention, a cover plate 6 covering the stack 2 of objects is provided that during the shrinking process preferably, and in the illustrated embodiment according to the figures, is spaced from the top face 7 of the stack 2 of objects. In the illustrated embodiment according to the figures, the cover plate is provided with an outlet port 8 for extracting the heated gases, or heated air generated during the shrinking process. In the illustrated embodiment, the cover plate 6 can be vertically displaced toward the top face 7 of the stack 2 of objects, and can be displaced away from the top face of the stack 2 of objects, and in this way, the space V between the cover plate 6 and top face 7 of the stack 2 of objects can be adjusted for the shrinking process. The figures show that according to a preferred embodiment, the cover plate 6 projects past the outer edge or rim of the top face 7 of the stack 2 of objects. Advantageously, the cover plate 6 projects past the outer edge or rim of the top face 7 on all sides. It is recommended that for the rest, the cover plate 6 is parallel or essentially parallel to the top face 7 of the stack 2 of objects. Preferably, and in the illustrated embodiment according to the figures, a blower 9 is located above the outlet port 8 with which the heated gases or the heated air can be removed by suction. It is also within the scope of the invention that the blower 9 is reversible and, if need be, cool gas or cool air can be fed in through the outlet port 8 for cooling purposes. Preferably, and in the illustrated embodiment, the cover plate 6 is displaceable independently of the displaceability of the shrink frame 3.

According to the invention, side walls 11 are provided between the shrink frame 3 and the cover plate 6 extending along side faces 10 of the stack 2 of objects. The side walls 11 are spaced from the side faces 10 of the stack 2 of objects. Between the stack 2 of objects and the side walls 11, clearances 12 are formed for the heated gases flowing upward. In FIGS. 1 and 6 to 8, only two opposing side walls 11 are shown. It is thereby within the scope of the invention that the stack 2 of objects is surrounded by side walls 11 on all sides so that a closed shell is formed. In the parallepipedal stack 2 of objects illustrated in the figures, four side walls 11 surrounding the stack 2 of objects are thus used. Advantageously, and in the illustrated embodiment according to the figures, the side walls 11 are vertical and preferably project above the stack 2 of objects or the top face 7 thereof. It is within the scope of the invention that the side walls 11 extend to the cover plate 6 or to the level of the cover plate 6. It is recommended and shown in the illustrated embodiment that the side walls 11 or lower ends of the side walls 11 are fixed to the shrink frame 3. According to one embodiment, the side walls 11 are fixed to one another at their corners. However, it is also within the scope of the invention that the side walls 11 only loosely overlap at the corners.

The method to be carried out by the apparatus according to the invention advantageously starts with the shrink frame 3 being moved to a lower region of the stack 2 of objects. The burners 5 can at this time already be operated in order to preheat the space around and above the stack 2 of objects. It is recommended that subsequently the shrink frame 3 is moved upward while operating the burners 5 so that the film 1 adhering to the stack 2 of objects is heated and shrink-fitted onto the stack 2 of objects.

During this shrinking process, heated gases are generated, in particular heated air that flow through the clearances 12 between the side walls 11 and the stack 2 of objects toward the cover plate 6 and to the outlet port 8. Thus, the heated gases are channeled at relatively close proximity past the film adhering to the stack 2 of objects above the shrink frame 3. This results in an effective preheating of the upper film segments, and this results in the considerable advantage that the output of the burners 5 of the succeeding shrink frame 3 can be reduced due to the film segments already being preheated for the shrinking process. This brings about a considerable saving in energy. The preheating is also effective on the film 1 on the top face 7 of the stack 2 of objects or a cover sheet film located there. For effective preheating, the space V can be adjusted here accordingly by the displaceable cover plate 6.

In the embodiment according to FIG. 1, rigid side walls 11 form a rigid frame that surrounds the stack 2 of objects and is open on the top. In this frame, or between the rigid side walls 11, the cover plate 6 can be vertically moved up or down. It goes without saying that the cover plate 6 must be displaceable in the frame with a certain amount of play. It is advantageous to seal the gap between the cover plate 6 and side walls 11 with the aid of a flexible sealing element or elements. Incidentally, in the illustrated embodiment according to FIG. 1, the rigid side walls 11 are preferably fixed to the shrink frame 3 with their lower ends.

FIGS. 2 to 5 show a particularly preferable embodiment of the apparatus according to the invention. In this embodiment, the frame is formed by a first partial frame or box 20 and by a second partial frame or box 21. Preferably and in the illustrated embodiment the first partial box 20 and the second partial box 21 are of rectangular cross-section. The first partial box 20 is an inner box engaged in the second partial box 21 as outer box. The subassembly of the first partial box 20 and the second partial box 21 telescopes. Advantageously and in the illustrated embodiment the first and the second partial box 20 and 21 are of the same height. Preferably, the second partial box 21 is connected to the shrink frame 3 at its lower end, and can thus move with the shrink frame 3 or move vertically downward. Incidentally, preferably, and in the illustrated embodiment, the walls of the first partial box 20 are connected to cover segments 22 that preferably and in the illustrated embodiment are perpendicular to the walls of the first partial box 20.

FIG. 2 shows the shrink frame 3 in an upper position. Here, the first partial box 20 is completely engaged inside the second partial box 21, and both partial boxes 20 and 21 rest on the shrink frame. In the functional position according to FIG. 3, the shrink frame 3 with the subassembly of the first partial box 20 and the second partial box 21 is moved further downward. The cover plate 6 suspended from rods 23 thereby draws close to the cover segments 22 of the first partial box 20. FIG. 4 illustrates that with further downward movement of the shrink frame 3 to a lower position, the second partial box 21 is guided down with the shrink frame 3 along the first partial box 20. Thus, the first partial box 20 pulls out of the second partial box 21. In the functional position of FIG. 4, the cover segments 22 of the first partial box 20 rest on the cover plate 6. Thus, the first partial box 20 is suspended from the cover plate 6. If need be, the cover plate 6, together with the first partial box 20, is now moved downward with the aid of a displacing unit 24 in order to adjust an optimal space V between the top face 7 of the stack 2 of objects and the cover plate 6.

FIG. 5 shows an embodiment with a stack 2 of objects of low height. In this embodiment, the subassembly of cover plate 6 and first partial box 20 is already completely moved downward so that the first partial box 20 also rests on the shrink frame 3. If need be, the cover plate 6 can now be moved further downward in the first partial box 20 in order to set a more favorable space V between stack 2 of objects and cover plate 6. In other words, the cover plate 6 is then moved in the subassembly of the first partial box 20 and the second partial box 21.

During the shrinking process in the embodiment according to FIG. 4, the shrink frame with the second partial box 21 is moved upward so that the second partial box 21 moves along the first partial box 20. In the variation according to FIG. 5, the shrink frame 3, together with the entire subassembly of second partial box 21 and first partial box 20 moves upward during the shrinking process.

In the illustrated embodiment according to FIG. 6, the side walls 11 are configured as flexible and heat-resistant or fire-proof walls 11. In the illustrated embodiment according to FIG. 6, the upper ends of the side walls 11 are connected to winders 13. During upward movement of the shrink frame 3, the flexible side walls 11 connected to the shrink frame 3 can be rolled off the winders 13 in accordance with the moving progression of the shrink frame 3 while the cover plate 3 maintains its position. It goes without saying that with an opposite movement of the shrink frame 3, the flexible side walls 11 are rolled up again onto the winders 13. Advantageously, and in the illustrated embodiment according to FIG. 6, the flexible side walls 11 are fixed to the shrink frame 3 at their lower ends.

In the embodiment according to FIG. 7, the inner shell 14 formed by the side walls 11 and the cover plate 6 is enclosed by an outer shell 15 with an upper outer plate 16 and outer side walls 17 such that the heated gases emerging from the cover plate 6 can flow back the shrink frame 3 in clearances 18 formed between the inner shell 14 and the outer shell 15. In this way, the excess heat of the heated gases is utilized for reducing the energy consumption of the shrink frame 3. Advantageously, in the illustrated embodiment in FIG. 7, both the inner shell 14 and the outer shell 15 are fixed the shrink frame 3. In the illustrated embodiment according to FIG. 7, the side walls 11 are configured as rigid side walls 11, and as in the illustrated embodiment in FIG. 1, the cover plate 6 can be vertically displaced in the frame formed of the rigid side walls 11. Furthermore, in the illustrated embodiment in FIG. 7, the outer side walls 17 are likewise of rigid design. Basically, in this embodiment, the side walls 11 and/or the outer side walls 17 could also be configured as flexible walls that can be rolled up or out.

In the illustrated embodiment in FIG. 8, an outer shell 15 over the inner shell 14 is also provided. However, in this embodiment, the side walls 11 of the inner shell 14 and the outer side walls 17 of the outer shell 15 are as bellows. By folding or unfolding the bellows like a concertina, both the cover plate 6 and the upper outer plate 16 can be adjusted to different heights of stacks of objects 2 without a problem, and in particular, the space V between the cover plate 6 and top face 7 of the stack 2 of objects can be adjusted subject to the shrinking process and subject to the height of the stack 2 of objects.

Claims

1. An apparatus for shrink-fitting a film onto a stack of objects with a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during the shrink fitting, the apparatus comprising:

a shrink frame with a plurality of heaters distributed around its periphery for heating the film for the shrinking process and causing gases to flow up around side faces of the stack,

a cover plate covering the stack of objects and spaced from the top face of the stack of objects during the shrinking process, and

side walls extending along the stack of objects below the cover plate, below the cover plate, and forming clearances between the stack of objects and the side walls for heated gases flowing upward, the cover plate being movable toward the top face of the stack of objects and away from the top face of the stack of objects, the side walls forming a rigid frame within which the cover plate can move.

2. The apparatus according to claim 1, wherein the rigid frame can be suspended from the cover plate, and in a suspended state, the frame can move with the cover plate.

3. The apparatus according to claim 1, wherein the frame has upper cover segments to form a box, and in a suspended state of the frame or box from the cover plate, the cover segments rest on the cover plate.

4. The apparatus according to claim 1, wherein the frame is formed by a first partial frame or box, and a second partial frame or box, the first partial box engaging with or being engageable with the second partial box, the cover plate being moveable in the first partial box or in the second partial box for adjusting a space between the stack of objects and the cover plate.

5. An apparatus for shrink-fitting a film onto a stack of objects, the apparatus comprising:

a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during the shrink fitting,

the shrink frame with a plurality of heaters distributed around its periphery for heating the film for the shrinking process and causing gases to flow up around side faces of the stack,

a cover plate covering the stack of objects and spaced from a top face of the stack of objects during the shrinking process, and

below the cover plate, side walls extending along the stack of objects and forming between the stack of objects and the side walls, clearances for the heated gases flowing upward, the side walls being made of a flexible material so that during downward movement of the shrink frame, the flexible side walls can be rolled off winders on the cover plate in accordance with the downward movement of the shrink frame.

6. The apparatus according to claim 5, wherein the inner shell formed of the side walls and the cover plate is enclosed by an outer shell having an upper outer plate and outer side walls such that the heated gases escaping from the cover plate can flow in the clearances formed between inner shell and outer shell to the shrink frame, or, vertically downward to the shrink frame.

7. The apparatus for shrink-fitting a film onto a stack of objects as defined in claim 1, the apparatus comprising

a shrink frame that can be moved over the stack of objects and that surrounds the stack of objects during the shrink fitting, the shrink frame being provided with a plurality of heaters distributed around its periphery for heating the film for the shrinking process and causing gases to flow up around side faces of the stack,

a cover plate covering the stack of objects, spaced from a top face of the stack of objects during the shrinking process,

below the cover plate, side walls are provided extending along the stack of objects, and wherein between the stack of objects and the side walls, clearances for the heated gases flowing upward are formed, and

an outer shell enclosing an inner shell formed of the side walls and the cover plate and having an upper outer plate and outer side walls such that the heated gases escaping from the cover plate can flow in the clearances formed between the inner shell and the outer shell to the shrink frame or, vertically downward to the shrink frame.

8. The apparatus according to claim 7, wherein the side walls of the inner shell or the outer side walls of the outer shell are configured in a bellows-like manner.

9. The apparatus according to claim 7, wherein the side walls of the inner shell or the outer side walls of the outer shell can be rolled onto winders, or can be rolled off the winders.

10. The apparatus according to claim 5, wherein the cover plate can be moved to the top face of the stack of objects and can be moved away from the top face of the stack of objects.

11. The apparatus according to claim 1, wherein the side walls or the lower ends of the side walls are fixed to the shrink frame.

12. The apparatus according to claim 1, wherein the cover plate covering the stack of objects is provided with at least one outlet port for extracting heated gases generated during the shrinking process, the apparatus further comprising:

at least one blower that can extract heated gases by suction, or with which cool gases or cool air can be fed in.

13. The apparatus according to claim 1, wherein the cover plate can be displaced or moved independently of the displaceability of the shrink frame.

14. In a method for shrink-fitting a film onto a stack of objects wherein the film is shrink-fitted onto the stack of objects with a shrink frame and for this purpose the shrink frame surrounding the stack of objects can be moved over the stack of objects, the film thereby being heated for shrink-fitting by a plurality of heaters distributed around the periphery of the shrink frame, the improvement comprising the steps of:

moving a cover plate above the stack of objects toward the stack of objects or away from the stack of objects for adjusting a space between the cover plate and stack of objects,

flowing heated gases generated during the shrinking process through clearances formed between the stack of objects and side walls connected to the shrink frame,

removing the heated gases are by suction through at least one outlet port provided in the cover plate, and

during the displacement toward the stack of objects and during the displacement in the opposite direction, moving the cover plate in a rigid frame formed of rigid side walls.

15. The method for shrink-fitting a film onto a stack of objects defined in claim 14, the method comprising the steps of:

shrink-fitting the film onto the stack of objects with a shrink frame surrounding the stack of objects by moving the shrink frame over the stack of objects such that the film is heated for shrink-fitting by way of a plurality of heaters distributed around the periphery of the shrink frame,

moving a cover plate above the stack of objects toward the stack of objects or away from the stack of objects for adjusting a height of a space between the cover plate and stack of objects,

flowing heated gases generated during the shrinking process through clearances that are formed between the stack of objects and side walls connected to the shrink frame,

removing the heated gases by suction through at least one outlet port provided in the cover plate, and

during displacement of the cover plate toward the stack of objects, rolling up the side walls as flexible side walls onto a winder, and during the displacement of the cover plate in the opposite direction rolling the flexible side walls off the winder again.

16. In the method defined in claim 14 for shrink-fitting a film onto a stack of objects where the film is shrink-fitted onto the stack of objects with a shrink frame surrounding the stack of objects and movable over the stack of objects such the film is heated for shrink-fitting by a plurality of heaters distributed around the periphery of the shrink frame, the improvement comprising the steps of:

moving a cover plate above the stack of objects toward the stack of objects or away from the stack of objects for adjusting a height of a space between the cover plate and stack of objects,

flowing heated gases generated during the shrinking process through clearances formed between the stack of objects and side walls connected to the shrink frame,

removing the heated gases by suction through at least one outlet port provided in the cover plate, and

enclosing the inner shell formed of the side walls and the cover plate by an outer shell having an upper outer plate and outer side walls such that the heated gases escaping from the cover plate can flow in the clearances formed between the inner shell and the outer shell to the shrink frame, or, vertically downward to the shrink frame.

17. The method according to claim 14, further comprising the step of:

initially moving the shrink frame at least to the bottom side of the stack of objects and

subsequently, during operation of the heaters for heating and for shrink-fitting the film, moving the shrink frame toward the top face of the stack of objects.

18. The method according to claim 17, further comprising the step of:

operating the heaters also during the displacement of the shrink frame to the bottom side of the stack of objects for heating the film.

19. The method according to claim 14, wherein further comprising the step of:

reducing a heat output of the heaters if the film is heated by the heated gases flowing to the cover plate.

20. The method according to claim 14, wherein the heated gases are removed by suction through the at least one outlet port in the cover plate with the aid of at least one blower.