EP1717148B1 - Method for wrapping products - Google Patents

Abstract

The assembly for wrapping loads or packaged goods (3), with a hood of an elastic film (25), gathers the film into pleats (26) to be laid in place and drawn, to be pulled over the packaged goods. The pleated film is drawn by a mobile covering unit (1) which pulls it over the package, using four stretching fingers (2) which can move on a plane at right angles to the covering direction (5). Each finger has a curved film tensioner (4) in this plane, and a support (6) in the covering direction to take the pleated film over the corners of the package, and draw it down over the package.

Description

The invention relates to a method for wrapping piece or packaged goods with an at least approximately hood-shaped elastic film section, which is folded by shirring and stretched and then pulled over the piece or packaged, wherein the shirred film section by means of a along the piece - Stretched or packaged movable overdrawing device and is pulled over the piece or packaged goods.

So that the shirred and as stretched film section that he can be covered over the piece or packaged goods, during the coating process easily and without damage can be deducted, the film section is gathered zieharonikaartig in the shirring process. After the shirring process, the folds should be oriented obliquely downwards towards the packaged item or packaged goods and pointing outwards. Only this uniform alignment of the folds ensures a later easy removal of the film section, since then fold by fold can be deducted from the overdrawing device.

A disadvantage of known methods proves that the wrinkles, however, do not always assume the desired uniform alignment. Rather, it is often found that the folding is done area by area more or less uncontrolled. Uncontrolled folding can occur during the shirring process or even during stretching.

However, if the folds do not have the desired orientation, the fold to be pulled off the adjacent fold which is to be peeled off in a next step is at least partially, if not completely, covered and thus pinched and held. This circumstance can lead to damage of the film section, since by pulling out this fold high tensions in the film section occur and so holes can be pulled into the film section. This risk is particularly great in film sections of small thickness, since then pull the film section easier when pulling out, or piece or packaged goods high altitude, as a greater length of film section gathered and therefore a greater number of wrinkles must be formed.

The object of the invention is to improve the previously known method in that during the coating process also at a non-optimal previous wrinkling damage to the film section can be prevented.

This object is achieved in that the shirred film section is stretched for coating over the piece or packaged goods in a first step by a first higher amount and in a second step, the stretching of the film section during the coating process of the shirred film section on the piece or packaged goods to a lesser amount, but still allows the coating is reduced, wherein the reduction of the stretch during the coating process of the film section on the piece or packaged continuously, in particular evenly, or the reduction of the stretch during the coating process of the film section over the piece - or packaged in stages, in particular multi-stage takes place.

In this respect, the film section is first stretched in a first step by an amount that is significantly above the stretch, as has been done in previously conventional methods. This stretching has been kept as low as possible on a regular basis and limited to the required for a proper implementation of the process minimum extension. In order to achieve this minimum extension, in known methods the film section is stretched by such a smaller amount that during coating there is an all-round distance between each side of the piece or packaged goods and the film section of 3 to 5 cm.

According to the method of the invention, the film section is first stretched in a first step by a greater amount, so that in this more stretched Condition adjusts an all-round distance between each side of the piece or packaged goods and stretched by the greater amount foil section of about 6 to 10 cm. Stronger extensions are possible.

By subsequently reducing the stretch of the film portion in a second step during the coating process - by moving respective components of the coating device, usually the clamping fingers - the tension in the folds of the gathered film portion is reduced, whereby the wrinkles, especially in a non-desired folding orientation, not more so strongly clamped by an adjacent fold and are held, so that the film section without damage can be easily removed during the coating process.

In this case, the reduction in tension may result from an at least partially delayed reset with a corresponding resulting, still beyond the minimum extent and / or at a successful default, which is less than the release occurring in the absence of all holding forces free reset, from the time offset with the one Tension is restored, resulting.

The higher amount of stretch is outside the tolerance range of the extension by the smaller amount and is clearly to be regarded as excessive compared to the extension by the smaller amount. The measure of the smaller amount of stretch, which corresponds to the minimum stretch, depends not only on the geometry of the piece or packaged goods. Other parameters, such. As the dimensions of the located within the film section system parts of the stall, have Influence on the measure of the smaller amount of stretch.

The reduction of the stretch to the smaller amount can be done with the first contact of the film section with the top of the piece or packaged goods or only at a later time during the coating process.

When using a one-step reduction, the complete coating process is at least for the most part completed before all recovery operations have been completed and the film section has again reached the extent afforded by the stretch to a lesser extent.

However, if piece goods or packaged goods of great heights are to be enveloped, there could be the risk that all restoring processes have already been completed in the film section before the completion of the coating process and the film section has reached its circumference, which it obtains by the extension by the smaller amount. In this case, it makes sense if the reduction takes place in multiple stages.

In the method for wrapping a piece or packaged goods with an at least approximately dome-shaped elastic film section, which is folded by shirring and stretched and then pulled over the piece or packaged, wherein the shirred film section by means of a piece or packaged goods stretchable puller is stretched and over the piece or packaged goods is pulled, according to the invention the overdrawing four in the plane perpendicular to the coating direction clamping fingers have, each having a substantially extending in this plane bow-shaped clamping element and an attached thereto arcuate, and pointing substantially in Überziehrichtung extending support member to the shirred film section in each of the corners of take to wrapping unit loads or packaged goods corresponding regions and then draw over the unit load and packaged goods, wherein at least on one tensioning finger a from the outside at least in the area of the unit load or packaged goods shortly before reaching the stall position at entferntesten, located over the unit load or Packaged good over fold, especially in the adjacent to this fold unfolded region of the film section, can be applied to the film section, baking-like and the corner region of the clamping finger at least partially embracing fixing device for clamping fixing the entspre chenden area of the film portion provided on the clamping fingers during stretching is, wherein at least one fixing device before stretching of the film section for fixing in the region of the corresponding clamping finger applied to the film section and removed after contact of the approximately hood-shaped film section with the piece or packaged from the film section. Due to the clamping fixation of the film section is secured when stretching on the clamping fingers from unintentional partial loosening during stretching, so that high degrees of stretch can be realized.

Advantageously, at least one fixing device can be applied again after removal of the folds shortly before removal of the film section from the access area of the fixing device for fixing the film section to this in the region of the corresponding clamping finger. By reapplying the fixing device shortly before completion of the coating process, the film section can be tightened in the coating direction and - if desired - also stretched, so that thereby high vertical degrees of stretch can be achieved. Following this, the fixing devices are again removed from the film section and the coating device is preferably returned to its original position.

The reduction of the stretch can be done in the first third of the coating process. The coating process begins with the contact of the film section with the top of the piece or packaged goods.

Preferably, the reduction of the stretch at a distance of 5 to 20 cm from the top of the piece or packaged goods, preferably at a distance of 10 cm from the top of the piece or packaged goods, take place.

Advantageously, the film section stretched by a higher amount in the first step is fixed at the beginning of the coating process by means of at least one fixing device, and the fixing device is removed again with a reduction of the stretch in a second step to a smaller amount from the film section. When the film section is coated, the film section stretched by the higher amount in the first step is first fixed. As a result, the film section sets only on the top side of the piece or packaged goods, while the sides of the piece or packaged goods are not in contact with the film section. By fixing vertical stresses can be introduced into the film section. In the further course of the coating process, the fixing device is then detached from the film section in a second step with reduction of the stretching to a smaller amount, so that then the film section can be pulled off fold by fold.

Fig. 1

eine Seitenansicht auf einen Spannfinger mit einem darauf gerafften Folienabschnitt und

Fig. 2

eine teilweise Draufsicht auf den Gegenstand nach Fig. 1.

In the following, an embodiment of the invention shown in the drawings will be explained. Show it:

Fig. 1

a side view of a clamping finger with a shirred film section and

Fig. 2

a partial plan view of the object after Fig. 1 ,

In all figures the same reference numerals are used for identical or similar components.

The FIGS. 1 and 2 show a coating device 1 of a device according to the invention. Not shown is an upstream in the process sequence shirring.

The coating device 1 has four clamping fingers 2, which are arranged in the respective corners of a piece or packaged goods 3 partially shown.

Each clamping finger 2 consists of an arcuately shaped tubular clamping element 4, which is aligned in a direction perpendicular to the coating direction 5 level.

To each clamping element 4, an approximately angularly shaped support member 6 is formed, which is fastened via a lower side cross member 7 to a support structure 8.

How out Fig. 1 can be seen, the two ends of the clamping element 4 are connected by a strut 9 with the corresponding support member 6.

On top of the cross member 7, a mast 10 is arranged. On this mast 10, a control lever 12 is rotatably struck by a bearing 11, at whose free end via a further bearing 13, a fixing device 14 is attached. The surface of the fixing device 14 that can be brought into contact with the clamping finger 2 is attached to the outer contour of the clamping finger 2. Since the support member 6 of the clamping finger 2 is formed approximately arcuate in the illustrated embodiment, so far, the fixing device 14 has a corresponding arcuate training. But it is also quite possible that the clamping finger 2 is provided at the level of the clamping element 4.

On the adjusting lever 12 engages a cylinder 15, which is shown in dashed lines in the figures. This may be, for example, a pneumatic or hydraulic cylinder.

As in particular from Fig. 2 shows, the clamping fingers 2 and thus also attached to the cross member 7 fixing device 14 along the longitudinal edges of the piece or packaged goods 3 (arrows 16, 17) are movable. In order to realize a movement in the direction of the arrow 17, the support structure 8 is connected via guides 18 with a guide rail 19. By means of the traverse 7 attacking chains 20, 21, the clamping fingers 2 can be moved in the direction of the arrow 17.

The guide rail 19 is arranged on the upper side of a holding element 22, that the overdrawing device 1 in the direction of arrow 16 is movable. The exact construction for enabling the travel in the direction of the arrow 16 is not shown for reasons of clarity.

In order that each covering device 1 can be moved in the direction of the arrow 23 along the piece or packaged goods 3, a hydraulic cylinder 24 is provided in the exemplary embodiment shown, which acts on the retaining element 22 on the underside. But there are also other constructions to achieve a mobility in the direction of arrow 23 is possible.

As shown in the figures, the four clamping fingers 2 engage in a downwardly opened film section 25. The film section 25 is already placed by gathering on the clamping fingers 2 in folds 26. The shirring itself is done in a separate shirring not shown. The film section 25 was taken over by the shirring device in the shirred state of the illustrated overdrawing device 1.

After taking over the shirred film section 25, each fixing device 14 is pivoted in the direction of the arrow 27 in the direction of the respective clamping finger 2, so that the film section 25 between the support member 6 of the clamping finger 2 and the corresponding fixing device 14 is fixed by clamping. In order to avoid damage to the film section 25, the area of the fixing device 14 which can be brought into contact with the film section 25 has a soft coating 28, such as, for example, B. sponge rubber, on. But there are also other coatings conceivable.

After applying the fixing device 14, the clamping fingers 2 to the outside, for example, diagonally outwardly in the direction of the arrow 29 moves apart, so that the film portion 25 is stretched. Due to the clamping fixation of the film portion 25 in the head area, d. H. In this case, the closed trained end to be optimally stretched.

After stretching, the overdrawing device 1 is moved in the overdrawing direction 5 along the piece or packaged goods 3. Once the head portion of the film section 25 rests on the top of the piece or packaged goods 3, the fixing devices 14 in the in Fig. 2 retracted dashed position shown. Upon further lowering of the overdrawing device 1, the folds 26 are increasingly withdrawn from the clamping fingers 2, so that when the overdrawing device 1 reaches its extreme lower position, the entire film section 25 has no more folds 26 and the piece or packaged goods 3 surrounds.

For the final tightening of the film portion 25 in the direction of coating 5 and possibly for stretching in coating direction 5, the fixing devices 14, shortly before the Film section 25 has been completely deducted from the clamping fingers 2, again in the in Fig. 2 moved position shown by solid lines, so that the film portion 25 is again fixed between the fixing devices 14 and the corresponding clamping fingers 2 by clamping.

In this way, the film section 25 can be optimally tightened and stretched in the direction of coating 5.

After tightening and, if necessary, stretching in coating direction 5, the fixing devices 14 are pivoted back, and the overdrawing device 1 again against the coating direction 5 in their original, in Fig. 1 moved position shown to take over another shirred film section 25.

Unless the wrinkles 26 are in Fig. 1 For a damage-free removal of the film section 25 from the clamping fingers 2, it is appropriate for the shirred film section 25 to be coated over the piece goods or packaged goods 3 in a first step by one stretched first higher amount and in a second step, the stretching of the film portion 25 during the coating process of the shirred film section 25 on the piece or packaged goods 3 to a lesser amount, but still allows the coating is reduced.

Hierduch the film portion 25 is first stretched in the first step by a greater amount, so that in this more stretched state, an all-round distance between each side of the piece or packaged goods. 3 and adjusts the film portion 25 stretched by the greater amount of about 6 to 10 cm. Stronger extensions are possible.

By the subsequent reduction of the stretch of the film section 25 in a second step during the coating process, the tension in the folds 26 of the gathered film section 25 is reduced by moving the clamping fingers 2 along the edges of the piece or packaged goods 3 (arrows 16, 17) the folds 26 are no longer so strongly clamped and held by an adjacent fold 26, so that the film portion 25 can be easily removed without damage during the coating process.

The reduction of the stretch can be carried out continuously or stepwise, in particular multi-stage.

In one embodiment, to produce both the higher or the higher stretch in the first step and the smaller stretch (minimum stretch) in the second step, one and the same component, e.g. As a geared motor can be used, which is driven accordingly.

Of course, it is also possible that two separate components, such. B. two geared motors or hydraulic cylinders, are provided, wherein the one component generates the extension by the smaller amount and beyond the stronger extension by the second, further component is realized.

Claims (7)

1. Method for wrapping unit loads or packaged goods (3) with a section of elastic film (25), which is at least approximately hood-shaped, is gathered into folds (26), stretched and finally pulled over the unit load or packaged goods (3), wherein the gathered section of film (25) is stretched and pulled over the unit load or packaged goods by means of a pulling-over device (1) that is displaceable along the unit load or packaged goods (3), characterised in that, to be pulled over the unit load or packaged goods (3), the gathered section of film (25) is stretched in a first step by a first higher amount and in a second step the stretching of the section of film (25) during the pulling of the gathered section of film (25) over the unit load or packaged goods (3) is reduced to a smaller amount, which, however, continues to enable the pulling-over procedure, wherein the reducing of the stretching during the pulling of the section of film (25) over the unit load or packaged goods (3) is effected in a continuous manner, more especially in an even manner.
2. Method for wrapping unit loads or packaged goods (3) with a section of elastic film (25), which is at least approximately hood-shaped, is gathered into folds (26), stretched and finally pulled over the unit load or packaged goods (3), wherein the gathered section of film (25) is stretched and pulled over the unit load or packaged goods by means of a pulling-over device (1) that is displaceable along the unit load or packaged goods (3), characterised in that, to be pulled over the unit load or packaged goods (3), the gathered section of film (25) is stretched in a first step by a first higher amount and in a second step the stretching of the section of film (25) during the pulling of the gathered section of film (25) over the unit load or packaged goods (3) is reduced to a smaller amount, which, however, continues to enable the pulling-over procedure, wherein the reducing of the stretching during the pulling of the section of film (25) over the unit load or packaged goods (3) is effected in a gradual manner, more especially in multiple stages.
3. Method according to claim 1 or 2, characterised in that the pulling-over device (1) includes four tensioning fingers (2), which are displaceable in the plane at right angles to the pulling-over direction (5) and include in each case a bow-shaped tensioning element (4), which extends substantially in the said plane, and an arcuate support element (6), which is secured to the said tensioning element and extends substantially in the pulling-over direction (5) in order to pick up the gathered film section (25) in each of the regions corresponding to the corners of the unit load or packaged goods (3) to be wrapped and then to pull it over the unit load or packaged goods (3), and in that at least on one tensioning finger (2) there is provided a jaw-like securing device (14), which can be placed in position on the film section (25) from externally at least in the region of the fold (26a) that is situated at the farthest point away from the unit load or packaged goods (3) shortly before the achieving of the pulling-over position and is to be pulled-over the unit load or packaged goods (3), more especially in the non-folded region of the section of film (25) abutting against the said fold (26a), the said securing device (14) embracing the corner region of the tensioning finger (2) at least in a partial manner and being provided for securedly clamping the corresponding region of the section of film (25) onto the tensioning fingers (2) during the stretching process, wherein at least one securing device (14) is applied to the section of film (25) before the stretching of the section of film (25) for securing in the region of the corresponding tensioning finger (2) and is removed from the section of film (25) after the approximately hood-shaped section of film (25) contacts the unit load or packaged goods (3).
4. Method according to claim 3, characterised in that, after pulling away the folds (26) shortly before the removing of the section of film (25) out of the access region of the securing device (14), at least one securing device (14) is once again applied to the section of film (25) to secure the said section of film in the region of the corresponding tensioning finger (2).
5. Method according to claim 2 or 3 or 4, in so far as claim 3 or 4 are dependent on claim 2, characterised in that the reducing of the stretching is effected in the first third of the pulling-over process.
6. Method according to claim 5, characterised in that the reducing of the stretching is effected at a spacing of between 5 and 20 cm from the top of the unit load or packaged goods (3), preferably at a spacing of 10 cm from the top of the unit load or packaged goods (3).
7. Method according to one of claims 1 to 6, characterised in that the section of film (25) stretched in the first step by a higher amount is secured at the start of the pulling-over procedure by means of at least one securing device (14) and the securing device (14) is removed again from the section of film (25) in a second step with reduction in the stretching to a smaller amount.

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