EP0399540B2 - Method and device for wrapping products in a hood of stretchable film and packaging unit shaped with this - Google Patents

Abstract

The invention relates to a method for wrapping products (2) - in particular stacked product parts such as, and in particular, substantially parallelipipedic or cubic product stacks consisting of a plurality of superposed and substantially flush layers of product - by means of a tubular section (1) of stretchable film whose original circumference is less than the circumference of the product (2) to be wrapped which, before being drawn over the product, is stretched in its circumferential direction to an extent which makes it possible to draw it effortlessly over the product, and which, after being drawn over, rests closely on the product with the expansion being retained, the section of stretchable film being sealed off at one of its ends, with the formation of a welded joint (13), to form a hood (1') of (stretchable) film, the weld extending, after wrapping, substantially centrally and parallel to two mutually opposite edges of the end faces (17) of the product, the length L of the welded joint being at least about 85 to 90% of the length of the edges of the end faces of the product stack which, in the wrapped state, are parallel to the said weld, and a device for carrying out the abovementioned method and a packaging unit to be formed by means of the abovementioned method and/or of the abovementioned device. <IMAGE>

Description

The invention relates to a method for wrapping General cargo - especially stacked general cargo parts such as e.g. and in particular i.a. by means of a palletizing device formed, essentially cuboid or cube-shaped batches of goods consisting of several one above the other arranged, i.a. essentially congruent General cargo layers exist by means of a tubular stretch film section, the unstretched The original scope is smaller than the scope of the piece goods to be encased, which before coating about the piece goods to be wrapped in its circumferential direction is stretched by a measure which makes it easy to put on enables about the piece goods to be wrapped, and the tight after stretching under permanent stretch lies against the piece goods, the tubular stretch film section to form a closed on one side (Stretch) foil hood at one end with formation a weld is welded after wrapping essentially in the middle and parallel to two opposite one another Edges of the face of the to be wrapped General cargo runs.

The invention further relates to a device for Wrapping general cargo according to the above procedure, among others four (spread) fingers or the like has which insert into the inside of the tubular film before wrapping are.

The invention further relates in particular to the above method and / or using the above Packaging unit to be formed.

For wrapping general cargo, especially palletized bulk stacks, for example made of cement, such as chemical Bulk goods or the like filled sacks and i.a. are formed by means of a palletizing device Known packaging processes in which the general cargo or the piece goods stack is covered with so-called shrink film, which is exposed to heat after wrapping and itself then firmly shrink to the piece goods to be wrapped creates a stack of packaged goods.

Within the scope of these known processes, i.a. so-called winding process known in which flat film around the to be wrapped General cargo / the stack of general cargo to be wrapped is wrapped, and so-called hood processes are also known for which have at least one (possibly also two) foil hood (s) pulled over the piece goods to be wrapped and then to this is shrunk.

Significant disadvantages of the shrink film packaging process exist among other things in that it was covered with shrink wrap General cargo may be subjected to heat for shrinkage got to. This not only leads to correspondingly high energy costs, but especially when it is applied with an open flame this procedure for flammable goods, such as and in particular are widely available in the chemical industry, not suitable due to the associated dangers are.

Another disadvantage of all shrinking processes is in that due to the required film thickness relatively high use of materials is required which leads to relatively high packaging costs because of film material especially since the known energy crises has become very expensive as a petroleum product.

In addition, the shrinkage is often considered to be little felt environmentally friendly, since this does not result in exhaust gases irrelevant scope arise, and since the operators are exposed to significant noise pollution.

In addition, when shrinking, sticking to the Well, what can often take place when unpacking corresponding damage to the piece goods leads and is particularly disadvantageous if, for example. consist of bags filled with bulk goods.

To avoid the above and other disadvantages, is accordingly one has already gone over to it instead of Shrink films to use so-called stretch films, which none Apply heat to adhere to what is to be packaged Create general cargo. Rather, it is sufficient if the stretch film material before wrapping the piece goods "stretched" (= stretched), under which (Technical) term "stretching" in general not any slight stretch of the starting material understands, but a considerable stretch of i.a. at least 10% and more, then in the wrapped state is also able to achieve the required stack strength Dimensional stability required by general cargo stacks to ensure. Such a stretch follows the wrapping so that the film material again contracts and thereby firmly adheres to the general cargo to be packaged.

Here the so-called winding stretching has become known, with the web-shaped stretch film - similar to the Wrapping shrinkage - wrapped around the piece goods to be wrapped becomes. Despite the shrinkage hereby achieved But winding stretching is not an advantage either insignificant disadvantages. These are for example in that the desired good load securing still is unsatisfactory, because when wrapping stretching only horizontal or only vertical clamping forces arise, if you don't have the piece goods to be wrapped in both Directions wrapped. The latter leads to one disproportionately high use of materials with corresponding Costs. It will also - albeit against shrinking lower - film consumption for reasons of cost than perceived unsatisfactory, this particularly because of this arises that the winding stretching is not insignificant Overlaps of two adjacent film webs required are.

In addition, to protect the surface of one on their Side surfaces wrapped with stretch film packaging unit a flat film is to be given as a cover sheet, and that with a separate cover sheet feeder a corresponding step is required. It can be in the area of such a cover sheet to corrugations and especially in the case of multiple handling Damage can occur because such a cover page is not under tension on the piece goods.

Overall, therefore, it should be noted that by winding stretch Packaged general cargo is often not sufficient is packaged in a weather-resistant manner because of the foil edges moisture often penetrates into the packaging unit can, and that also the view of the packaged piece goods is often imperfect when wrapping into one often hardly avoidable crease comes.

One has therefore already gone over to packaging General cargo or batches of items to be packed with a Cover the stretch film foil hood like this basically known from shrink film packaging was. However, in particular in the area of Weld seam result in significant problems so far are not solved satisfactorily.

A weld seam is made with stretch film hoods For reasons of economy, each from a section a tubular film material are formed, just as inevitable as this with shrink film hood processes the case being, which is below Difficulties with shrink wrap packaging detailed below using foil hoods due to the heat exposure and the Restructuring of the molecules is nowhere near have shown as much as this has previously been the case with stretch film hood processes the case is.

Such tubular film material is known to have a folded, as it were flat initial state, in which the tubular film material two to each other parallel first side faces and two each V-shaped has inwardly folded second side surfaces. This folding is therefore useful to such a thing Tubular film material as space-saving as possible (and thus i.a. even with a relatively small width) coiled into rolls to be able to store. I.ü. has been shown that tubular film material folded in this way in the stored state can be opened better than this is when the tubular film material is a hood former is fed in the unfolded state in which the tubular film width therefore equal to half the circumference of the tubular film is.

In the case of one of the notifying parties (as well as of competitors) Welding has been carried out until now of a tubular film section in each case not yet stretched original state such that the corresponding End section of the tubular film section practically in the supplied form (and thus also the corresponding Storage width of the tubular film) was welded, the weld seam therefore had a length that the Width of the parallel first side faces corresponded to the tubular film.

Because the circumference of the tubular film is not vertical Intended condition noteworthy as intended (partly entirely is considerably smaller than the length of the front edges of the piece goods / piece goods stack to which the weld seam in the wrapped state runs parallel, the weld seam inevitably with this method of stretching and necessarily subjected to a very considerable stretch, and not just when stretching in front of the Wrapping the piece goods / piece goods stack in which the Tubular film must be expanded so far that it effortlessly over the general cargo / the general cargo stack can be drawn, but also afterwards in the enveloped Status. This is evident from the fact that a The stretch film hood is also still intended under (sometimes considerable) elongation when it is firm lies against the piece goods / piece goods stack, whereby stretching up to 30% and more can be provided (see e.g. DE-A-37 07 877).

This procedure then occurs, as already has been hinted at in the area of the weld Problems, especially in the places those with such a tubular film hood inevitably arising tip in the wrapped state on the relevant end face of the piece goods / piece goods stack lie on one another.

In the case of DE-A-37 07 877 already mentioned above known processes (presumably in an effort to to avoid the problems outlined above) one completely different way chosen, namely the foil before Welding opened and stretched (crosswise) and she first then in the desired length from the tubular film stock detached and welded, so practically no more folded and already stretched state, taking inevitably results in a weld whose length in Elongation condition before covering (considerably) larger is as the length of the in the wrapped state parallel to the front edge of the weld seam enveloping piece goods / piece goods stack.

Such a formation of the weld seam can now have the consequence that the existing in the film material internal stresses during the welding process plasticization of the film material (largely or even essentially completely) lost go so that even after finishing the welding process practically not in the welded section are more present, but in the rest of the film material remain so that it is particularly in the Boundary areas between weld seam and neighboring Foil material can tear or even tear, especially in the case of multiple envelopes formed in this way Packing units, what then with corresponding tears to a loss of the required stack strength can always lead to a loss of the desired Tightness leads.

The present invention is based on the object the known methods and devices and thus not least the packaging units to be formed with it to improve that so far in the weld area as well as occurring in the neighboring areas Problems avoided or at least on a harmless one Dimension can be significantly reduced.

As a solution to the procedural part of this task the invention provides the features of the characterizing part.

Especially in the most preferred method, at with the length of the weld seam before (cross) stretching a length is formed that is practically the same Length of the face edges parallel to it in the encased state of the piece goods, occur in the finished Wrapping condition of the packaging unit no harmful Tensions increase and there are no breaks, unwanted corrugations and the like because of the weld in the unstretched (unstretched) initial state the stretch of the film material more or less exactly has the same length as in the wrapping state. This results in (especially compared to one Design in which the weld seam length is clear is smaller than the corresponding stack length) the considerable advantage that the occurring Tensions essentially perpendicular to the weld set and no longer under random or random Angles to the weld, the latter in particular in the V-shaped double areas of the Foil can lead to overstretching, in particular such that larger ones in the film below Tensions occur than in the upper section of the film. In contrast, in the configuration according to the invention, that the inner film tensions in the overhead Foil section are each larger than in lower (which can be largely free of tension), so that the lower sections of the film are V-shaped Duplication range easily under the tension of the Place the upper film sections on the piece goods and the live upper film sections for ensure a smooth surface.

The practically unstretched state of the welded area not any adverse side effects because in this Area for the desired tight or tight wrapping of the general cargo no stretch tensions required are.

Even if this condition is actually only reached if the length of the weld is equal to the length of the in the encased state parallel to the end margins of the piece goods to be wrapped is selected Effect of a significant improvement over the previous one known generic methods can already be seen then qualitatively and already in a quantitatively highest to reach remarkable and noticeable proportions when the length of the weld seam is chosen to be only slightly smaller than the length of the one parallel to it in the wrapped state Front edges of the piece goods to be wrapped, so for example 95% of this length.

In order to achieve the goal of the invention, it can Use of the usual folded film tube material, which has two mutually parallel first side surfaces as well as two V-folds folded inwards has second side surfaces, may be required tubular film material before welding to deform its end section to be welded, if necessary, that the two mutually parallel first side surfaces while reducing the size of the V-shaped, folded inwards second side surfaces (or if necessary with enlargement of the V-shaped second side surfaces) the desired length the weld seam. So then the Storage width of the tubular film material before Welding process and before stretching i.a. enlarged to the desired size of the weld seam and the relevant tubular film section is only then after welding with the appropriate weld length stretched and in the process on a piece goods (stack) concerned adapted shape, so that this way formed stretch film hood effortlessly over what is to be wrapped General cargo can be drawn. When stretching to oversize the weld seam area is then generally stretched a bit, however, this stretching condition is due to the invention Dimensioning of the weld seam in the coating state practically back to zero since the unstretched According to the invention, the weld seam length is essentially the same the length of the welded in the wrapped state parallel end wall edges was formed.

This adjustment of the tubular film material kept in stock to the desired welding width in particular To be able to implement expediently is a device to carry out the method according to the invention, the generally four (spread) fingers or the like. having, which are to be inserted into the inside of the tubular film, to open them completely and (cross) them, according to the invention designed so that the fingers first movable into a first position or working position are in which the length of the parallel first side walls of the tubular film the desired length has the weld, and that the fingers or the like. first after that (namely after welding) into a second Position can be moved in which the tubular film is stretched to its overstretched state.

Preferred configurations of the present invention are described in subclaims.

Fig. 1

eine Seitenansicht auf einen Schlauchabschnitt, wie er üblicherweise zur Bildung einer Folienhaube verwendet wird;

Fig. 2

eine Draufsicht auf den Folienabschnitt gemäß Fig. 1 in leicht geöffneter Stellung in Richtung des Pfeiles II in Fig. 1 gesehen;

Fig. 3

eine Seitenansicht auf einen zu umhüllenden Stückgutstapel mit darüber angeordneter, zu einer Folienhaube zu verarbeitender, von einem aufgerollten Folienvorrat zugeführter Schlauchfolie;

Fig. 4

eine Draufsicht auf die Schlauchfolie gemäß Fig. 2, nachdem (Spreiz-)Finger in das Innere der leicht geöffneten Schlauchfolie eingefahren sind;

Fig. 5

die Schlauchfolie gemäß Fig. 4, nachdem ihre ersten Seitenflächen (unter Verkürzung der V-förmig eingefalteten zweiten Seitenflächen) wenigstens am Abschweiß-Endabschnitt auf eine Länge gebracht worden sind, die der Länge der zu bildenden Schweißnaht entspricht;

Fig. 6a

eine Seitenansicht auf die Schlauchfolie gemäß Fig. 5 in Richtung des Pfeiles VI gesehen nach Anlegen von Schweißbacken;

Fig. 6b

nach Bildung der Schweißnaht; und

Fig. 6c

in (quer-)gestretchter Übergröße vor dem Überziehen;

Fig. 7a

eine Draufsicht auf den mit der Stretchfolienhaube umhüllten Stapel nach dem Überziehen der Folienhaube; und

Fig. 7b

im Vergleich dazu eine Ansicht gemäß Fig. 7a des mit einer Folienhaube überzogenen Stückgutstapels, dessen Folienhaube in konventioneller Weise mit einer Schweißnaht versehen ist, welche vor dem Stretchen in einer der Breite des zugeführten Folienschlauches entsprechenden Länge ausgeführt worden ist.

The invention is explained below using an exemplary embodiment with reference to a drawing. It shows:

Fig. 1

a side view of a tube section, as is usually used to form a film hood;

Fig. 2

a top view of the film section of Figure 1 seen in a slightly open position in the direction of arrow II in Fig. 1.

Fig. 3

a side view of a piece of goods to be wrapped with a tubular film arranged above it, to be processed into a film hood, supplied from a rolled film supply;

Fig. 4

a plan view of the tubular film according to FIG 2, after (spread) fingers are inserted into the interior of the slightly open tubular film.

Fig. 5

the tubular film according to Figure 4, after its first side surfaces (shortening the V-shaped folded second side surfaces) have been made at least at the welding end portion to a length which corresponds to the length of the weld seam to be formed;

Fig. 6a

a side view of the tubular film of Figure 5 seen in the direction of arrow VI after applying welding jaws.

Fig. 6b

after formation of the weld seam; and

Fig. 6c

in (cross) stretched oversize before covering;

Fig. 7a

a plan view of the stack covered with the stretch film hood after covering the film hood; and

Fig. 7b

in comparison to this, a view according to FIG. 7a of the stack of articles covered with a film hood, the film hood of which is provided in a conventional manner with a weld seam, which was carried out before stretching in a length corresponding to the width of the supplied film tube.

1 to 4 show that of a roll-up Tubular film stock coming free end section the tubular film 1 designed as a stretch film, the width B corresponding to the width of the storage a piece goods stack 2 according to arrow 3 in Fig. 3 from above is fed in the middle, and the folded in Storage and supply condition two parallel to each other first side surfaces 4.1 and 4.2 and two each V-shaped second side surfaces 5.1 and 5.2 folded inwards has, which each consist of two legs of equal length 6.1.1 and 6.1.2 or 6.2.1 and 6.2.2 exist.

1 shows a side view of the tubular film 1 seen in the direction of arrow I in FIG. 2 and FIG. 2 a section through the tubular film 1 of FIG. 1 in Seen in the direction of section line II-II, however already in a slightly opened state, in which already (spread) fingers 7 (see FIGS. 4 and 5) or the like. can be inserted into the interior of the tubular film 1. Such opening of the tubular film 1 from the state of storage, in the adjacent first and second side surfaces 4 or 5 are touching each other, can for example by suction beam 8 or the like. (see Fig. 2) take place at the free end section of the tubular film 1 be applied from the outside to the first side surfaces 4 and then according to arrows 9 (see FIG. 2) for a corresponding one Are movable apart.

3 shows the relative assignment in a side view of the free end section of the tubular film 1 into one with a stretched film hood to wrap stacked goods 2, to allow understretching on its underside 10 on the substrate 11 by means of a support means 12 is supported, the area of which is smaller than the bottom 10 of the piece goods stack 2.

Since according to the invention the length L at the upper end of the Stretch film section weld seam 13 (see e.g. Fig. 6b) substantially equal to length l the face edges parallel to it in the encased state of the general cargo stack 2 should be the stocking and so that the feed width B of the tubular film 1 less than the length l of the relevant front edges of the piece goods stack 2, and since the weld seam 13 expediently in the unstretched state of the tubular film material is to be produced, therefore Width B of the supplied tubular film 1, that is the length their mutually parallel first side surfaces 4, initially be enlarged accordingly.

In the present case, this happens because the Fingers or the like 7, which later to fully open the Tubular film 1 and used for stretching, 4 retracted into the slightly open tubular film whose lower section i.ü. to make it possible the lowest possible height by means of suitable Devices are folded zigzag folded and that the fingers 7 accordingly initially in the direction of the arrows 14 parallel to the first side surfaces 4 with their enlargement and corresponding reduction of the second Side surfaces 5 are moved so far out the length B 'of the first side surfaces 4 at least in designated welding area equal to the specified one or the intended length L of the weld seam to be formed is, namely the length l of the in the wrapped state Weld 13 parallel front edges of the packaged goods 2nd

It is obviously not necessary that the Extend finger 7 into the welding area. Much more this can remain free, so that according to FIG. 6 Welding jaws 15 can be applied to the weld 13 to form (see Fig. 6a and b).

Then the fingers 7 can then be moved according to the arrows 16 (see FIG. 5) with the tubular film 1 fully opened be extended diagonally and if necessary also the Carry out (transverse) stretching, in which the now formed film hood 1 'in relation to the piece goods stack 2 is brought to an excess which allows that then from above over the general cargo stack 2 is pulled, with its lower edge portion the bottom 10 of the general cargo stack 2 shrunk and the film hood 1 ', thus, under permanent stretch, firmly on the piece goods stack 2 is present.

7a shows a top view of the one with the film hood 1 ' enveloped piece goods stack 2. It can be seen that the Length of the weld 13 practically equal to the length l of the parallel to the end edges 17.1 and 17.2 of the General cargo stack 2 is, and that the weld 13 so again has the length l, which it already has before Had stretching. Of course, it was according to FIG. 6c during the (transverse) stretching of a certain stretch in Subject to the transverse direction, but this stretching is possible through the training according to the invention can be seen in essentially return to zero, so that so far in the range the weld 13 occurring problems not only reduced to a different degree, but practical are completely eliminated.

To make this clearer, FIG. 7b shows one 7a on a with a film hood 1 ' wrapped stack of goods in which the weld 13 ' in a conventional way before stretching in a length B has been carried out, the width of the fed Tubular film 1 corresponds. As stated, this with the result that the weld seam 13 '(its length is considerably smaller than the length l of the one in the encased Condition parallel to the end margins 17.1 and 17.2 of the general cargo stack 2) not only when stretching Oversize (for covering the stack of items 2) considerably (more) is stretched, but that the weld 13 ' especially in the wrapped condition with a fixed system the film hood 1 'on the piece goods stack 2 in a substantial Stretching condition remains, with the result that it is particularly in the tip areas 18 to considerable voltage peaks comes, which in turn comes in particular with a multiple handling to tear and thus to remove protection against weather influences and possibly even to the disappearance of the required dimensional stability of the packaging unit being able to lead.

As has already been explained above, this is Objective according to the invention can also be seen in qualitative Then already in relation to the prior art to achieve if the length of the weld 13 in the unstretched Condition not exactly the length l of it parallel end edges 17 of the piece goods stack, but, for example, with a planned elongation of 12.5% 5% smaller than the length L, as can be seen even then the stress conditions that arise with conventional working methods already be significantly reduced, namely usually to a harmless level.

Claims (7)

1. A method of wrapping piece goods or a stack (2) thereof in a hood (1') of stretch film, in which, before stretching, a hood (1') is formed from a stretchable laterally pleated tube (1) supplied from a store and, in the storage and supply state, comprising two parallel closely adjacent first side surfaces (4, 4) having a given (supply) width (B) and two intermediate V-shaped inwardly folded second side surfaces (5, 5') and an at least 10% smaller periphery than the piece goods or stack (2) to be wrapped, the hood being formed by the laterally pleated tube (1) being welded with a transverse seam (13) at a distance from its free end and cut from the supply behind the portion forming the hood (1'), the hood (1') being completely opened for the purpose of pulling it over the piece goods or stack (2) and stretched along substantially the entire length to the extent required for pulling it over, characterised in that the laterally pleated tube (1) is given a transverse seam (13) having a length (= ideal length) substantially equal to the width (1) parallel to the transverse seam (13) of the piece goods or stack (2) to be wrapped, and in cases where the (supply) width (B) of the laterally pleated tube (1) is not equal to the ideal length of the transverse seam (13) to be formed, before the transverse seam is positioned at least the top end portion of the part of the laterally pleated tube (1) for (subsequently) forming the hood (1') is given a width equal to the ideal length of the transverse seam (13); and in that the film hood is so stretched that the bottom film portions bear against the piece goods in the V-shaped doubling zone under the stress of the upper film portions.
2. A method according to claim 1, characterised in that the length (L) of the transverse seam (13) is at least approximately 95% of the width (1) of the piece goods (2) parallel thereto.
3. A method according to claim 1 or 2, characterised in that after the transverse seam (13) has been positioned, the hood (1') formed from the laterally pleated tube portion is stretched so that the film material forming the side surfaces of the stretch film wrapping is substantially uniformly stretched at all side surfaces.
4. A device for wrapping piece goods or a stack (2) thereof in a hood (1') of stretch film, the device comprising a welding means (15) by means of which, before stretching, a hood (1') is formed from a laterally pleated tube (1) having an at least 10% smaller periphery than the piece goods or stack (2) to be wrapped, the hood being formed by the laterally pleated tube (1) being welded with a transverse seam at a distance from its free end, the device also comprising a cutting means for cutting the laterally pleated tube (1) behind the portion forming the hood (1'), and four expanding fingers or the like (7) which are inserted into the interior of the laterally pleated tube portion forming the hood and are moved apart for stretching, for working the method according to any of claims 1 to 3, characterised in that the expanding fingers (7) or the like are sufficiently dimensioned to engage in the upper end portion of the part of the laterally pleated tube for (subsequently) forming the hood (1'), in that the expanding fingers (7) or the like, in cases where the (supply) width (B) of the laterally pleated tube (1) is less or greater than the ideal length of the required transverse seam (13), in a first working step (Fig. 5) are moved into a first operating position with simultaneous partial consumption or simultaneous deepening of the side pleats (6.1.1, 6.1.2; 6.2.1, 6.2.2) without stretching the film material, until the web width (B') of the laterally pleated tube (1), altered from the original (supply) web width (B), is equal to or slightly less than the width (1) of the stack (2) of piece goods and therefore equal to the ideal length of the transverse seam (13); and in that after the transverse seam (13) has been positioned, in a second working step the expanding fingers (7) are moved apart into a second operating position until the hood (1), after being completely opened, is finally stretched to a predetermined extent required for pulling over.
5. A device according to claim 4, characterised in that in the second working step, the expanding fingers (7) or the like are moved so that the film material forming the side surfaces of the hood-like stretch-film wrapping is substantially uniformly stretched at all side surfaces.
6. A unit load made up of piece goods wrapped in a hood of stretch film formed from a laterally pleated tube having an at least 10% smaller periphery than the piece goods to be wrapped and provided before stretching with a transverse seam at a distance from its free end, formed by a (working) method according to any of claims 1 to 3 and/or by a device according to claims 4 or 5, characterised in that the length (L) of the transverse seam (13) before stretching is at least about 95% of the width (1) of the piece goods (2) parallel to the transverse seam (13).
7. A unit load according to claim 6, characterised in that the length (L) of the transverse seam (13) is substantially equal to the width (1) of the stack (2) of piece goods.

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