EP0461564B1 - Apparatus for wrapping products in strechable film - Google Patents

Description

The invention relates to a device for wrapping piece goods with stretch film according to the preamble of claim 1.

Such a device has become known from DE 39 18 311 A1 after the shrink film technology for the creation of loading units had lost considerable importance for technical and economic reasons and has essentially been replaced by the stretch film technology. Although the stretch hood method has proven to be particularly useful for creating transport-secured and weather-resistant loading units, it has been shown that the lower edge region of the stretch film hood is a loading unit that can be created with a generic method or a generic device and that can handle the general cargo or a the pallet supporting pallet in the finished state (with a so-called "understretch") should reach under (in particular with additionally applied vertical stretch) has an inclination up to the underside of the palletized goods to be wrapped or over the pallet or the like to be palletized . to slide up at least partially during the pulling process. In addition, reinforcement of the film wrapping appears to be desirable, particularly in the case of packaged goods supported on a pallet in the lower edge region, since pallets made of wood are regularly not smooth, especially on their end faces, and accordingly tend to perforate the film forming the wrapping, so that in such cases the Weather protection in single-layer film wrapping is endangered to this extent.

From DE-AS 12 98 444 a reinforcement of the film material through the formation of three-layer film sections is known in principle, but in this known loading unit these are on the top (and also in the upper stack edge area) and therefore do not form a reinforcement of the lower edge section provided according to the invention the stretch film hood, which is formed from the hood material.

Furthermore, reference is made in this connection to DE 90 01 319 U1, in which it is recommended to turn over the lower edge of the hood by means of a device (to be arranged under the stack of items or its carrier) which grips the edge of the hood, driven guide rods and, if necessary Has welding devices in order to be able to place the lower edge of the hood under the underside of a piece goods stack and / or its carrier, fold there and, if necessary, weld it. Such an embodiment is, however, very complicated in terms of both method and device and does not lead to satisfactory results.

FR-A-2 566 739 discloses a method for wrapping piece goods stacked on pallets with a film hood, in which the lower hood edge is turned over once or twice for reinforcement, the clamping pliers or the like holding the hood edge. maintain an unchanged distance with respect to their relative position to the stack of goods. This often leads to poor positioning of the hood edge on the stack of items or on the pallet, in particular when the hood is stretched vertically considerably when pulled over.

The present invention has for its object to improve the known generic device in such a way that the reinforced lower edge portion of the film wrapping compared to the rest of the film wrapping in a technically simple and economically satisfactory manner can be safely positioned at the intended location of the packaged goods / pallet.

The solution to the above object is achieved by the characterizing features of claim 1. It has been shown that even with considerable vertical stretch there is always a safe positioning of the hood edge when the bracket or the like. be brought close to the stack / pallet when the reinforcement is formed.

In a most preferred embodiment of the device according to the invention it is provided, among other things, that the bracket at least are to be moved closer to the piece goods between the first and second lowering positions than their distance during the other covering process, in order to ensure the desired formation of folds and thus at least two layers of the lower film edge section.

Since it has been shown that the cross-stretched film held in a reefed form on the lifting frame during the pulling process over the piece goods should have a not inconsiderable distance to the predetermined (theoretical) outside of the piece goods in order to avoid a collision with the piece goods in irregularly formed formations , on the other hand, for the fold formation already discussed above and thus multilayering of the lower film edge section, a close proximity of the brackets to the piece goods or to the pallet supporting this has proven to be extremely useful, is provided in a further embodiment of the present invention that at least one on each bracket Sensor is arranged, by means of which a minimum distance between the bracket and the general cargo or the pallet is maintained.

In this context, reference is made to the prior art on GB-PS 13 33 125, which already discloses a sensor for keeping away.

In order to ensure a simple and safe detachment of the film from the brackets in the (raised) second lowering position, it can be provided that a gas, in particular compressed air, is blown between the bracket and the film in the higher second lowering position, for which purpose it is extremely high It may be expedient if the brackets are provided with gas line openings at their sections which come into engagement with the film and which are connected to a compressed gas source. It has continued to be extremely useful emphasized to make the blowing pressure and / or the amount of gas supplied over time controllable by means of a control device.

This measure (s) means, in particular, practically no additional effort if - as has already been proposed according to an older proposal by the applicant - the bow-shaped frame sections are designed in any case to control the coefficient of friction between the film material and the lifting frame or the bow-shaped frame sections to be able to.

As an alternative or in addition to this measure, in another embodiment of the present invention, the brackets can be designed to be pivotable away from the piece goods or the pallet, it having proven to be particularly expedient if the brackets are to be pivoted in each case about a lower end section of the bracket support, it has furthermore proven to be highly expedient if the brackets can be swiveled as they pivot away from the second working position into the third working position, as will be explained in more detail below using exemplary embodiments.

In a further expedient embodiment, reversibly drivable reefing rollers are provided, in a further embodiment in the second or third lowering position with the direction of rotation reversed, as in the case of reefing, these re-engaging with the bottom edge portion of the foils in order to form a two-layer or preferably three-layer loosen lower edge area of the lifting frame.

Preferred embodiments of the present invention are described in the subclaims.

The invention is explained below using exemplary embodiments with reference to a drawing.

Fig. 1

eine etwas schematische räumliche Darstellung eines mit einer Stretchfolienhaube zu überziehenden Stückgutstapels, wobei die Stretchfolienhaube aus einem Seitenfaltenschlauch gebildet wird, der in Fig. 1 an seinem freien Endabschnitt bereits von dem Hubrahmen aufgenommen worden ist;

Fig. 2

in einer Fig. 1 entsprechenden Darstellung die Anordnun gemäß Fig. 1 nach Bilden einer Stretchfolienhaube;

Fig. 3

in einer Darstellung gemäß den Fig. 1 und 2 die gemäß Fig. 2 gebildete Stretchfolienhaube nach dem/beim Querstretchen;

Fig. 4

in einer Darstellung gemäß den Fig. 1 bis 3 einen Zwischenzustand beim Überziehen des Stückgutstapels mit der Stretchfolienhaube;

Fig. 5

eine Seitenansicht eines Bügels nebst dessen Stütze in Richtung des Pfeiles V in Fig. 6 gesehen;

Fig. 6

eine Draufsicht auf zwei (von vier) Bügeln;

Fig. 7

eine teilweise schematisierte Seitenansicht auf einen auf einer Einwegpalette abgestützten Stückgutstapel mit einem Bügel in einer unteren Absenkstellung;

Fig. 8

in einer Darstellung gemäß Fig. 7 den Bügel in seiner ersten Absenkstellung;

Fig. 9

in einer Darstellung gemäß den Fig. 7 und 8 den Bügel in seiner zweiten Absenkstellung;

Fig. 10

in einer Darstellung gemäß den Fig. 7 bis 9 die Ausgestaltung des unteren, dreilagigen Randabschnittes der Stretchfolienhaube im fertigen Zustand der Ladeeinheit; und

Fig. 11

in einer Darstellung gemäß Fig. 10 den unteren Randabschnitt der Stretchfolienhaube bei einer zweilagigen Variante.

It shows:

Fig. 1

a somewhat schematic spatial representation of a piece of goods to be covered with a stretch film hood, the stretch film hood being formed from a gusseted tube which has already been received by the lifting frame in FIG. 1 at its free end section;

Fig. 2

in a representation corresponding to FIG. 1, the arrangement according to FIG. 1 after forming a stretch film hood;

Fig. 3

in a representation according to FIGS. 1 and 2, the stretch film hood formed according to FIG. 2 after / during transverse stretching;

Fig. 4

in an illustration according to Figures 1 to 3, an intermediate state when covering the piece goods stack with the stretch film hood.

Fig. 5

a side view of a bracket and its support seen in the direction of arrow V in Fig. 6;

Fig. 6

a plan view of two (out of four) brackets;

Fig. 7

a partially schematic side view of a piece goods stack supported on a one-way pallet with a bracket in a lower lowered position;

Fig. 8

7 shows the bracket in its first lowered position;

Fig. 9

7 and 8 the bracket in its second lowered position;

Fig. 10

in a representation according to Figures 7 to 9, the design of the lower, three-layer edge portion of the stretch film hood in the finished state of the loading unit. and

Fig. 11

10 the lower edge section of the stretch film hood in a two-layer variant.

1 shows a block-shaped piece goods stack, designated as a whole by 1, which consists of several layers of piece goods parts which are intended to be wrapped with a stretch film hood 2 in order to form a loading unit. The stretch film hood 2 is formed from a gusseted tube 3, which is fed to the device according to the arrows 8 from a gusseted tube supply, not shown, the free end of the gusseted tube 3 according to FIG 3) has been included.

As has been indicated in Fig. 2, the gusseted tube 3 is welded at a distance from its free end by means of a welding device 4, which consists essentially of two welding conductors, so that a transverse seam 5 is formed, and above the transverse seam 5 by means of one shown separator to form a stretch film hood 2 separated, the side surfaces in the state shown in FIG. 2 are already substantially (by means of a reefing device) on the lifting frame 9.

From the state shown in FIG. 2, the four brackets 9 ', which essentially form the lifting frame and are respectively assigned to the corner regions of the stack of articles 1, are moved apart in the direction of the arrows 6 for the purpose of transverse stretching of the stretch film hood 2. Then the stretched stretch film hood 2 according to FIG. 4 is pulled over the stack of goods 1 by means of the lifting frame 9, which also forms a reefing frame, FIG. 4 showing an intermediate state in which the stack of goods 1 is already about half wrapped.

4, the lifting frame 9, which can be driven by means of a drive (not shown), then moves further downward, initially into a position as can be seen in FIG. 7, only one bracket 9 ′ being recognizable in FIG. 7 is, but the other brackets 9 'are at the same level.

Before the further wrapping process is explained in detail below, the specific configuration of the stirrups 9 'will be explained in more detail, in particular with reference to FIGS. 5 and 6, and reference should first be made to the fact that the piece goods stack 1 - as shown in FIGS. 1 to 4 can be seen - is supported on a (one-way) pallet 10.

As has already been stated, the lifting frame 9 consists of four substantially C-shaped brackets 9 ', each of which is provided with a plurality of through bores 13, which are connected to a compressed air source, and in each case one in engagement with foils during operation Section of the outside of the relevant lifting frame section 9 'open. The schematically indicated in Fig. 6 Compressed air source is designated 14.

Each bracket 9 'is supported by a support 17 (see FIGS. 5 and 6) formed by a curved, conical sheet metal, the supports 17 each having a recess 18 in the central region. Otherwise, the through bores 13 connected to the compressed air source 14 are connected to a control device 16 (see FIG. 6) by means of which the air pressure or the amount of compressed air supplied over time can be controlled.

As can be seen from FIG. 7, the brackets 9 'of the lifting frame 9 are first moved to below the upper side 10' of the pallet 10 during the pulling process, FIG. 7 showing an intermediate position and the lower end position has not yet been reached. It can be seen from FIG. 7 that already in this intermediate position the gusseted tube 3 or the (side surfaces of) the stretch film hood 2 essentially envelop the piece goods stack 1. 7, the brackets 9 'of the lifting frame are not only moved further in the direction of arrow 19 into a first lowering position (see FIG. 8), but at the same time they also continue to move according to arrow 20 the general cargo stack 1 or the pallet 10 moved up. While the clear distance during the essential covering process, taking into account empirically determined tolerance values, was a (see FIG. 7), in the position according to FIGS. 8 and 9 with the value b (see FIG. 9) it is only considerably less.

In the first lowered position according to FIG. 8, the lifting frame 9 or its bracket 9 ′ is then raised again into a second lowered position according to FIG. 9 raised relative to this, in which the film 2 or 3 on the one hand forms a double-layer fold 21 on lower general cargo edge area or on the pallet 10 and on the other hand still to the Ironing 9 'is present (see Fig. 9).

Only then are the brackets 9 'brought into / out of the raised second lowering position according to FIG. 9 out of engagement with the film 2 or 3 and finally - after moving apart against the direction of the arrow 20 in FIG. 7 - back into the starting position pulled back.

In order to bring about a release of the film 2 or 3 from the brackets 9 'in the second lowering position according to FIG. 9, a gas, in particular compressed air, can be blown between the brackets 9' and the film 2 or 3, specifically through the with a compressed air source 14 and through holes 13 controlled by means of a control device 16 (see FIGS. 5, 6), the coefficient of friction between the film and the material of the stirrups 9 ′ being initially reduced with the possibly blown-in air, but the film if necessary can also be "blown off" from the bow-shaped frame sections 9 '.

Alternatively or additionally, in the second lowered position, the brackets 9 'can also be pivoted sideways away from the piece goods 1 or the pallet 10, as is indicated by an arrow 22 in FIG. 9, that is to say in the exemplary embodiment shown, in each case around a lower end section 23 the respective support 17.

As has already been indicated above, additional sliding fingers or the like could possibly also be provided for detaching the film 2 or 3 from the lifting frame 9 or its brackets 9 ', but it is clearly considerably more advantageous if the invention is based on such maintenance-intensive and sensitive additional devices can be dispensed with, although an integral arrangement of such sliding fingers or the like. would be a technically and economically acceptable solution directly on the lifting frame 9, while its separate Design and arrangement must be regarded as a highly unsatisfactory solution, both in technical and in economic terms.

As an alternative or in addition, the reefing device mentioned above can be provided with reversibly drivable reefing rollers 24 for impacting the film material on the lifting frame 9 (in particular its supports 17), which in the second or possibly a third, lowered position relative to the second (after reefing again) are to be brought into engagement with the lower edge section of the film 2 or 3, but then with a direction of rotation according to arrow 25 (see FIG. 9), which is opposite to the direction of rotation of the reef rollers when reefing.

Regardless of whether the configurations or measures described above by way of example are used alternatively or cumulatively, the end result is a loading unit 26, as is shown schematically in the detail in a representation in accordance with FIGS. 7 to 9 in FIG. 10, that is to say with a three-layer structure lower film edge section 27, which in the illustrated embodiment bears against the upper layer 28 of the pallet 10.

Fig. 11 shows a variant in which the lower film edge portion 27 'is formed only in two layers, this film design has been achieved in that the lifting frame 9 has been pivoted away from its second lowered position according to FIG. 9 and / or the reefing rollers 24 at if necessary, not yet swung away reef rollers 24 have brought the bottom edge of the stretch film hood 2 into the position shown in FIG. 11 (that is to say in an upward contact with the top layer 28 of the pallet 10).

Claims (11)

1. Apparatus for wrapping unit loads (1) which may or may not be supported on a pallet (10) or the like, with a stretch film (2, 3) in tube or hood form, more particularly for wrapping unit loads of parallelepipedal or cubic shape stacked one upon the other in several layers, comprising a reefing and stretching reciprocating frame (9) which is adapted to be driven, and which carries a plurality of bowed members (9') which, in plan view, are bent to be substantially L or C-shaped and which are disposed in a horizontal plane, together with supports (17) each holding the bowed members, that section of the film which forms the side surface wrapping being reefed on to said frame by reefing rollers (24) before the film is drawn over the unit load, the reefed film (2, 3) being transversely stretched by said frame before the film (2, 3) is drawn over the unit load, while the bowed members (9') during the drawing of the film hood (2) over the unit load (1) are initially lowered, while still in engagement with the film hood, in manner known per se, into a first lowered position (Fig. 8) situated beneath the unit load (1) or in the region of a pallet (1) or the like supporting the unit load, whereupon the bowed members are lifted out of said first lowered position (Fig. 8) into a second lowered position (Fig. 9) in which the film (2 or 3) on the one hand abuts the bottom edge zone of the unit load or the pallet (10), while forming a double-layered fold (21), and, on the other hand, still abuts the bowed members (9') of the frame (9), the bowed members (9') in the second lowered position (Fig. 9) being disengaged from the film (2 or 3) and then finally returned to their initial position, characterised in that the bowed members (9') at least during the first and second lowered positions (Fig. 8 and Fig. 9) are brought closer to the unit load (1) than their distance (a) during the other draw-over operation.
2. Apparatus according to claim 1, characterised in that at least one sensor is disposed on each bowed member (9') to maintain a minimum distance (b) between the bowed member (9) and the unit load (1) or the pallet (10).
3. Apparatus according to claim 1 or 2, characterised in that a gas, more particularly compressed air, is blown between the bowed member (9') and the film (2 or 3) in the higher second lowered position (Fig. 9) of the bowed members (9').
4. Apparatus according to claim 3, characterised in that those portions of the bowed members (9') which come into engagement with the film (2 or 3) are provided with gas conduit orifices (13) connected to a compressed gas source (14).
5. Apparatus according to claim 4, characterised in that the gas pressure and/or the amount of gas fed per unit of time is controllable by a control device (16).
6. Apparatus according to any one of claims 1 to 5, characterised in that the bowed members (9') are adapted to swing away from the unit load (1) or the pallet (10).
7. Apparatus according to claim 6, characterised in that the bowed members (9') are each pivotable about a bottom end portion of the bowed member support (17).
8. Apparatus according to claim 6 or 7, characterised in that the bowed members (9') are each movable from the second lowered position (Fig. 8) into a third lowered position.
9. Apparatus according to claim 8, characterised in that the bowed members (9') are each lowered into the third lowered position during their pivoting out of the second lowered position (Fig. 8).
10. Apparatus according to any one of claims 1 to 9, characterised by reversibly drivable reefing rollers (24).
11. Apparatus according to claim 10, characterised in that the reefing rollers (24) in the second or third lowered positions are again brought into engagement with the bottom edge portion of the film (2 or 3) in the reverse direction of rotation to that applicable during reefing.

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