EP1013549A1 - Method and device for enveloping a stack of goods - Google Patents

Abstract

The procedure involves making a tubular hood(18) made of a highly elastic film and which with a longitudinal stretch of at least 50 per cent in relation to the unstretched hood is laid upon the stack of loose items. The longitudinal stretch is produced at least partially by drawing the film over the items. The film in the transverse direction is stretched by at least 50 per cent, and preferably 80 per cent, in relation to the unstretched hood. An Independent claim is included for a device for wrapping a stack of loose items which has a longitudinal stretching component designed so that the hood in the longitudinal direction is elastically stretchable by at least 50% of its unstretched length.

Description

The present invention relates to a method and a device suitable therefor for enveloping one of a plurality of piece goods arranged one above the other formed piece goods stack, in which tubular film is pulled off to form a tubular hood, opened, matured lengthways and separated from the tubular film and sealed the reefed tubular film is subsequently stretched in the transverse direction and is then pulled over the piece goods stack with longitudinal expansion.

Such a method is known from EP-B-0 344 815. With this previously known The procedure uses a stretch tube, the elasticity of which is limited. So will with the above-mentioned prior art, the film tube by a maximum of 15% stretched. This measure is intended to cause the packaged goods stack to collapse due to delayed venting of piece goods, such as not completely bags filled with general cargo can be compensated. The applied longitudinal stretch of A maximum of 15% should prevent the reduction caused by the post-venting the stack height to a slackening of the wrapping the piece goods Tubular film and thus leads to a reduction in stack strength.

However, the method known from the aforementioned prior art has for example, the disadvantage that the covered with the hose hood General cargo stack formed prepackaging unit does not have the necessary dimensional stability has when individual piece goods vent and decrease in volume, the General cargo parts lying above follow the lowering movement of the vented general cargo part and thus inevitably increase the pressure on the respective general cargo part, which too increased ventilation of the general cargo item or items under increased pressure leads. These processes sometimes result in slippage within of the general cargo stack. The top of the piece goods stack then no longer runs parallel to the bottom of the packaging unit, which is generally formed by a pallet. If several packaging units are stacked on top of each other during transport or handling are arranged, this can cause the load to slip and possibly wedge to lead.

Otherwise, the previously known stretch film tends due to the predominantly plastic Elongation of the film, the edges of individual layers of the general cargo stack under plastic Enclose deformation. The compensation of lowering movements through the stretching hood can therefore be done at most in individual layers, and it has shown that with the previously known method in particular in the middle of the side walls only an insufficient longitudinal stretch can be applied.

Proceeding from this, the object of the present invention is a method specify with the packaging units using a hose hood are formed, can be produced, which have an increased dimensional stability. The present invention is also based on the object of performing one to specify suitable device of the method.

To solve the procedural part of the above object is with the present Invention a method with the features of claim 1 specified.

According to the invention, the hose hood is formed from a highly elastic film. This highly elastic film shows a linear increase even with total strains above 30% in the stress-strain diagram and can be significantly more than 150% (total) be stretched in the longitudinal direction of the hose hood. Such highly elastic Films are in the prior art, for example in the manufacture of pant diapers known. Furthermore, elastic films are, for example, from EP-A-0 081 328 known in connection with the winding stretch. It turned out to be one an elastic film hose hood formed with an elastic longitudinal expansion of at least 50% in relation to the unstretched hose hood on the piece goods stack is applied to a considerable rubber-like bracing of the packaged goods leads in the longitudinal direction. This tension in the longitudinal direction is in the inventive Process evenly when pulling the hose hood over the General cargo stack applied. Accordingly, the general cargo stack becomes even compressed during manufacture of the packaging unit, so that a significant part of the the method known from the prior art approved for a long time Venting of general cargo parts is forced immediately when the packaging unit is manufactured becomes. This results, for example, in the case of multiple handling Packaging unit only negligible ventilation of the packaged General cargo that no longer or only insignificantly affects the dimensional stability of the general cargo stack. With the method according to the invention accordingly produce packaging units using a hose hood, the top of which, even with longer transport or multiple handling within of the limits to be demanded parallel to those usually formed by a pallet Bottom of the packaging unit runs. In particular tilting or slipping of stacked packaging units can be used when using the method according to the invention can be avoided.

ungedehnte" Schlauchhaube im Sinne der vorliegenden Erfindung ist dabei eine zur Umhüllung eines üblichen Stückgutstapels verwendete Schlauchhaube anzusehen, die weder in Längs- noch in Querrichtung gedehnt ist, also beispielsweise eine Schlauchhaube, die an ihrem verschlossenen Ende aufgehängt ist und die lediglich durch das zu vernachlässigendes Eigengewicht gedehnt ist.Practical tests have shown that, in particular, a film can be used for the hose hood, which has an elongation of 50% at a tension of approx. 4-10 N / mm ² and which has an elongation above approx. 30-50% shows linear increase in the stress-strain diagram with a slope of 0.5-2 N / mm ² per 50% strain. Such a highly elastic film already produces a considerable tensile force in the longitudinal direction with an elastic longitudinal expansion of at least 50% compared to the unstretched tubular film. As one

Unstretched "hose hood in the sense of the present invention is to be seen here as a hose hood used to encase a conventional stack of piece goods, which is neither stretched in the longitudinal nor in the transverse direction, for example a hose hood which is suspended at its closed end and which is only negligible due to the fact that it is negligible Dead weight is stretched.

It has been shown that the above-described, almost rubber-like bracing of the piece goods stack improved in the longitudinal direction with increasing elongation values can be. With higher elastic expansion values, the hose hood tends less the edges of individual layers of the piece goods stack on the outer peripheral surface to enclose plastically, which is beneficial to the uniform tensile stress the top edge of the stack of goods when pulling over the hose hood affects. Accordingly, longitudinal strains of at least 80% are preferred of at least 100% and particularly preferably of at least 150%, over that prefer unstretched hose hood when putting it on the piece goods stack. It has been found that an elastic elongation of more than 300% is difficult to handle mechanically. Currently an elastic Longitudinal elongation of a maximum of 200% is regarded as sufficient by far can be advantageous in particular with regard to a risk of tearing of the film to limit elastic elongation to approx. 160%.

The tensile stress described above on the top of the piece goods stack is favored in that the shirred film in the transverse direction by at least 50% compared to the unstretched hose hood. This stretch in the transverse direction takes place on the reefed film, i.e. before applying the film to the top of the general cargo stack. With a transverse expansion of over 20%, the hose hood placed on the top of the piece goods stack in such a way that in a subsequent Longitudinal expansion of the hose hood, the generated longitudinal tensile force evenly in particular is introduced into the stack of packaged goods over the entire upper edges. About that In addition, a significant transverse elongation of at least 50% is preferred, preferably the hose hood is reset by at least 80% after the stack of articles has been pulled over, since the open ends of the hose hood are under the stack of the pallet holding the general cargo stack, releasing the elastic transverse expansion components moves in. This measure prevents the longitudinally stretched Hose hood relaxes and moves towards the top of the General cargo stack withdraws.

It has also proven to be advantageous to at least partially extend the longitudinal extension to be generated when the hose hood is pulled over the piece goods stack. Is it is also possible, for example, to stretch longitudinally before stretching in the transverse direction to generate when reefing the tubular film. However, this has disadvantages for transverse stretching, since the longitudinal expansion leads to a certain solidification of the hose hood and thus higher forces are required for the transverse expansion.

For the device-based solution of the above-mentioned object, the present Invention proposed a device with the features of claim 5.

According to a preferred embodiment, the longitudinal stretching device of the covering device for covering the hose hood over the stack of goods in a known manner Have four spreading fingers movable at least in the longitudinal direction, each of which at least one drive roller is assigned with which the hose hood is bellows-like can be reffected via the spreading fingers. In order to considerably stretch the hose hood Apply the required forces in the longitudinal direction with a structurally simple design To be able to, the preferred embodiment of the device according to the invention has a formed on the spreading fingers, extending in the axial direction of the drive roller concave trough, delimited by a cylindrical surface, into which the drive roller is retractable. The hose hood can thus at least with linear pressure transmission clamped between the spreading finger and the drive roller assigned to it become.

With regard to clamping as flat as possible for the transmission of high frictional forces Avoiding a film tear is a flat contact between the drive roller and to prefer the spreading finger with the interposition of the hose hood. Accordingly points in a preferred embodiment of the device according to the invention the concave trough has a slightly larger radius of curvature than the drive roller. It is also preferable to use an elastic circumferential surface of the drive roller To dress material. Alternatively or additionally it is used to increase the friction between the hose hood and the drive roller are preferred on the peripheral surface the drive roller to provide suction holes through which the hose hood is sucked and the most flat possible application of the hose hood to the drive roller favor.

In addition to the drive roller, each spreading finger can have one or more pressure elements be assigned, which act at least when pulling on the hose hood. Such a pressure element is part of the longitudinal expansion device and clamps the hose hood preferably when pulling the hose hood over the piece goods stack such that the frictional forces exerted by the pressure element are greater are than the forces required to smooth the shirred film.

According to a further preferred embodiment of the present invention, this is Pressure element can be driven. The pressure element, as well as the drive roller, if necessary be able to be driven in the direction of reef when the hose hood is pulled over, i.e. the pull-off movement counteract the hose hood. The drive roller and the pressure element can alternatively also the pull-off direction when pulling on the hose hood are driven to support the piece goods stack, with the setting of desired longitudinal expansion, the peripheral speed and / or the rotational or Braking torque of the drive roller or the pressure element is controlled. This points the device according to the invention preferably a control device with which the Torque or braking torque of the drive rollers and / or the pressure elements when tightening the hose hood is controllable.

Fig. 1

eine Seitenansicht eines Ausführungsbeispiels einer erfindungsgemäßen Vorrichtung;

Fig. 2

eine Draufsicht auf ein erstes Ausführungsbeispiels eine Refffinger;

Fig. 3

eine Seitenansicht des in Fig. 2 gezeigten Refffingers

Fig. 4-6

einen Teilbereich der in Fig. 1 gezeigten Vorrichtung in verschiedenen Verfahrensstadien;

Fig. 7

eine der Fig. 2 entsprechende Darstellung für ein alternatives Ausführungsbeispiel eines Reffingers und

Fig. 8

eine Seitenansicht des in Fig. 7 gezeigten Reffingers.

Further details, features and advantages of the present invention result from the following description of a preferred exemplary embodiment. The drawing shows:

Fig. 1

a side view of an embodiment of a device according to the invention;

Fig. 2

a plan view of a first embodiment of a reef finger;

Fig. 3

a side view of the reef finger shown in Fig. 2

Fig. 4-6

a partial area of the device shown in Figure 1 in different process stages.

Fig. 7

a representation corresponding to FIG. 2 for an alternative embodiment of a finger and

Fig. 8

a side view of the reef finger shown in Fig. 7.

The embodiment shown in Fig. 1 comprises a device according to the invention a device frame 1, between the vertical stands a lane 2 to Feeding and removal of piece goods stacks 3, each of a plurality of one above the other arranged general cargo parts are formed, is arranged. On the fixture frame 1, a roll 4 is mounted on which a tubular film 5 is wound. Are there the side edges of the tubular film 5 folded in the wound state. The Tubular film 5 is a guide device via guide rollers 6 and take-off rollers 7 fed, which has vertically movable guide elements 8. The device further comprises a separating device 9 and a welding device 10.

Below the guide elements 8 are in a known manner on both sides of the device frame 1 roof-shaped double conveyor belts 11 arranged, the upper Receiving ends immediately below the guide elements 8 in their vertically lowered Position.

On the four stands of the device frame 1, carriages 12 are in a vertical direction or longitudinal direction of the supplied tubular film 5, on each of which Spreading finger 13 is attached. The spreading fingers supported on the four stands 13 have brackets 14 running horizontally, each approximately at right angles to one another are arranged. Each spreading finger 13 is connected to a drive device 15 supported a corresponding stand of the device frame 1. The drive device 15 is formed here from a hydraulic cylinder, all of which Longitudinal axes of the hydraulic cylinders approximately at the center of the device frame are aligned and lie in an approximately horizontal plane. In the feed direction the tubular film 5 in front of the spreading fingers 13 is a drive roller 16 on the outside Carriage 12 mounted, which is movable in the horizontal or transverse direction. With the shown In the exemplary embodiment, the longitudinal axis of the drive roller 16 extends parallel to a respective side surface of the piece goods stack 3.

2 and 3 show a spreading finger 13 and a bracket assigned to it 14 in detail. The illustrated embodiment of a spreading finger 13 has a flat one outer contact surface 13a, which is between the bracket 14 and the fastening side End of the spreading finger 13 extends on the outside thereof. Below the bracket 14 is a concave depression 13b is formed on the contact surface 13a and is formed by a cylindrical surface 13c is limited. The concave trough 13b extends parallel to the axial one Direction of the drive roller 16, which is indicated in Fig. 3 with a dashed line. It is the ratio of the radii of curvature of the drive roller 16 on the one hand and the cylindrical surface area 13c, on the other hand, is chosen such that in the retracted one indicated in FIG State of the drive roller in the trough 13b between the drive roller 16 and the trough 13b an annular segment-shaped gap 17 is formed. Accordingly, the Radius of the drive roller a little smaller than the radius of curvature of the cylinder surface 13c. In the exemplary embodiment shown, the annular gap 17 a wrapping of the drive roller 16 through the tubular film 5 of approximately 60 ° is achieved become.

In the exemplary embodiment shown in FIGS. 2 and 3, the contact surface 13a is in Feed direction of the tubular film 5 below a straight end portion 14a of the bracket 14 arranged. The formation of the contact surface 13a and the arrangement thereof relative to the bracket 14, however, is at the discretion of the person skilled in the art. The only essential thing is that the drive roller 16 and the trough 13b are aligned with each other such that the tubular film 5 at least linearly when the drive roller 16 is retracted into the trough 13b, preferably along the longitudinal axis of the drive roller between the trough 13b and the drive roller 16 is clamped.

The process sequence for wrapping a piece goods stack 3 is described below in particular explained in particular with reference to FIGS. 4-6:

The flat tubular film 5 is in a manner known per se by the take-off rollers 7 threaded over the guide elements 8. At the bottom of the guide elements everyone will folded edge of the tubular film 5 between a double conveyor belt 11 passed open the hose (Fig. 4). After the lower end of the tubular film 5 Has run out of the double conveyor belts 11, the take-off rollers 7 as well as the double conveyor belts 11 stopped and the spreading fingers 13 are in the Hose end retracted. When the spreading fingers 13 reach a predetermined position have, the drive rollers 16 are moved to the spreading fingers 13. Here moves a part of the peripheral surface of the respective drive roller 16 into the trough 13b of the associated Spread fingers 13 and clamps the tubular film 5 in the gap 17. Then the drive rollers 16 together with the take-off rollers 7 and the double conveyor belts 11 put into operation until a predetermined length of tubular film 5 bellows-like, i.e. is meandering over the spreading fingers 13 (Fig. 5). Now become the separating and welding devices 9 and 10 actuated to the withdrawn, below of the separating and welding devices 9, 11 located section of the tubular film 5 to form a hose hood 18 of a predetermined length closed at the top. After that the double conveyor belts 11 are driven again and pivoted in a known manner, to release the remaining part of the hose hood 18 which may can be stretched tightly over the bracket 14 by starting the drive rollers 16 again can.

Starting from this starting position, the spreading fingers 13 are moved apart in the transverse direction. In the embodiment shown, the movement of the Spreading fingers 13 diagonally opposite the base of the piece goods stack 3 Transverse stretching presses the drive rollers 16 with the hose hood 18 in between continue against the spreading fingers 13, so that an unwanted pulling out of the reefed Hose hood 8 is avoided. During the transverse movement of the spreading fingers 13, the Hose hood 8 by at least 50%, preferably by at least 80% the unstretched hose hood stretched. There is in particular a transverse expansion of a total of 50% with an elastic portion of the elongation of at least 20% prefer what is explained below.

After the transverse expansion has ended, a state is reached as can be seen in FIG. 1 is. The spreading fingers 13 are together with the drive rollers 16 on the respective Carriage 12 moves uniformly towards the stack 3. It lies down the upper closed end of the hose hood 18 formed by welding initially on the surface of the piece goods stack 3 and encloses due to the transverse expansion the outer upper edges of the piece goods stack as the Slide 12 flush.

The hose hood 8 is placed on the sides of the stack 3 in one elastic elongation of at least 50%, compared to the unstretched Hose hood 18. For this purpose, the drive rollers 16 are rotated with a predetermined rotation or Braking torque controlled, the sliding out of the reefed hose hood material through the gap 17 only after exceeding the desired elastic Longitudinal expansion allows. In contrast to the previously known hood stretch, at a film is used, the elastic expansion of which is at most of the order of magnitude the plastic stretch lies and therefore when it is placed on the piece goods stack in particular to a plastic deformation along by the individual General cargo formed contour tends and individually encloses the general cargo layers, the elastic tubular film 5 when pulled over the piece goods stack 3 like a rubber band Walk over the individual layers of the general cargo parts. The hose hood 18 lies therefore only firmly on the upper edge of the stack 3. The even, through the drive roller 16 controlled pulling force in the longitudinal direction leads to a uniform Load of the piece goods stack 3, which during a venting of piece goods parts of covering the hose hood 18 to the desired dimensional stability forming packaging unit ensures and in particular ensures that the top the piece goods stack 3 essentially even with stronger ventilation phenomena parallel to the bottom of the packaging unit formed by a pallet runs.

On the way of the sled 12 downward, the hose hood 18, initially reefed, becomes pulled by the spreading fingers 13 and with elastic longitudinal expansion to the piece goods stack 3 laid. The spreading fingers 13 are located at the end of this downward movement approximately at the level of the lower edge of the piece goods stack 3. The elastic portion of the The tube hood 18 can now be stretched transversely by releasing the remaining length the hose hood 18 can be relaxed, the spreading fingers 13 being relative to this the piece goods stack 3 are preferably arranged such that the inward relaxing hose hood 18 pulls at least partially under the pallet. At a Such a procedure should be taken into account when adjusting the transverse expansion that the hose hood 18 pulls under the pallet in such a way that the elastic, Hose hood 18 pulled over the piece goods stack not due to the elastic Longitudinal expansion is pulled upwards. Therefore, it is preferable to overcoat the hose hood 18 has an elastic transverse expansion of at least 50% and particularly preferably at least 80%. Alternatively or additionally the lower edge of the hose hood 18 can be attached to the pallet, for example by brackets, which however means a later removal of the hose hood 18 problematic for exposing the general cargo parts. Alternatively, the free can End of the hose hood 18 also in the area of the pallet with the packaging unit are glued or welded, preferably for such a connection in Area of the pallet, especially between the lowest general cargo layer and the pallet, a film can be arranged with which the covered hose hood 18 is connected becomes.

The device according to the invention is not limited to the exemplary embodiment shown, For example, in addition to the drive roller 16, pressure elements, in particular Drive rollers or rollers can be provided which the hose hood 18 at Clamp over the stack 5 and clamp the reefed hose hood 18 first release if a specified elongation or tension value is exceeded.

An exemplary embodiment of a pressure element 19 is shown in FIGS. 7 and 8. It is a segment of a circle, the curved area of the bracket 14 surrounding element, the radius of curvature approximately the radius of curvature of the curved area of the finger 14 corresponds (Fig. 7). The finger 14 facing The contact surface of the contact element 19 is concave and has a radius of curvature on, which corresponds approximately to the radius of the cross section of the bracket 14. Here, too, are the radius ratios between the curvature of the bracket or the radius of the Cross-section of the bow on the one hand and the radius of curvature of the pressure element 19 or the radius of curvature of the contact surface chosen such that the between the bracket 14 and the pressure element 19 held film is pressed flat. For pressing on and releasing the film between the bracket 14 and the pressure element 19 is one Actuating device, not shown, is provided, which the pressing element 19 with an angle of approximately 45 ° to the longitudinal axis of the respective straight end sections 14a of the bracket 14 and preferably connected to a central control device is to control the desired longitudinal expansion.

Reference list

1

Fixture rack

2nd

roadway

3rd

General cargo stacks

4th

role

5

Tubular film

6

Pulleys

7

Take-off rolls

8th

Guiding elements

9

Separator

10th

Welding device

11

Double conveyor belt

12th

carriage

13

Spreading fingers

13a

Contact surface

13b

trough

13c

Cylinder surface

14

hanger

14a

straight end section

15

Drive device

16

Drive roller

17th

gap

18th

Hose hood

19th

Pressing element

Claims (10)

Method for wrapping a stack of piece goods formed from a plurality of piece goods arranged one above the other, in which tubular film is pulled off to form a hose hood, opened, reefed in the longitudinal direction and separated from the hose film and closed, the reefed hose hood is subsequently stretched in the transverse direction and then stretched longitudinally the general cargo stack is pulled,
characterized by
that the hose hood is formed from a highly elastic film, which is applied to the piece goods stack with a longitudinal expansion of at least 50% compared to the unstretched hose hood. A method according to claim 1, characterized in that the tubular film is applied to the piece goods stack with a longitudinal expansion of at least 80%, preferably at least 100% and particularly preferably at least 150% compared to the unstretched hose hood. A method according to claim 1 or 2, characterized in that the longitudinal expansion is at least partially generated when it is pulled over the piece goods stack. Method according to at least one of the preceding claims, characterized in that the shirred film is stretched in the transverse direction by at least 50%, preferably by 80%, compared to the unextended hose hood. Device for enveloping a piece of goods stack formed from a plurality of piece goods arranged one above the other with a hose hood, the device comprising a covering device for pulling the hose hood over the piece goods stack, which has a transverse and a longitudinal stretching device for the hose hood,
characterized by
that the longitudinal stretching device is designed such that the hose hood (18) is elastically stretchable in the longitudinal direction by at least 50% of its unstretched length. Apparatus according to claim 6, wherein the longitudinal stretching device has at least four spreading fingers movable at least in the longitudinal direction, each of which is assigned at least one drive roller, with which the tubular film can be reefed like bellows over the spreading fingers, characterized in that an axially extending on the spreading fingers (13) Concave trough (13b) extending in the direction of the drive roller (16) and into which the drive roller (16) can be moved. Apparatus according to claim 6, characterized in that the concave trough (13b) and the drive roller (16) have essentially the same radius. Apparatus according to claim 6 or 7, characterized in that each spreading finger (13) is assigned at least one pressure element (19) which acts on the hose hood (18) when it is pulled over. Device according to claim 8, characterized in that the pressure element can be driven. Device according to at least one of Claims 6 to 9, characterized by a control device acting on each drive roller (16) and / or each pressure element, with which the torque of the drive rollers (16) and / or the pressure elements can be controlled when the hose hood (18) is pulled over.

Images