DE19955478B4 - Stretch winders - Google Patents

Abstract

Stretch winders (17) for wrapping a loaded pallet (2) with a foil (3), comprising a stretch head (4) which is rotatable about an axis (6) mounted film roll (7), and a guide means (5), characterized characterized in that the guide means (5) is designed as a six-axis articulated robot, with the Stretch head (4) with at least three degrees of freedom within a working space around the loaded pallet (2) is feasible, wherein more than two axes of the guide device (5) are designed to pivot.

Description

The The invention relates to a stretch winder for wrapping a loaded one Pallet with a foil, with a stretch head, which rotates one about an axis has stored film roll, and a guide device. The invention further relates to a device with a stretch winder.

When Stretch winder is referred to as a machine that uses pallets Wrap film around the products placed on the pallet against environmental influences to protect. Preferably, a film is used, which is in the stretch process under an elongation, in a 100 to 300 percent elongation the film can exist, can be processed.

The Film is characterized by the pre-stretch during winding in the molecular structure so stabilized that they are harder and more resistant becomes. After wrapping, the film shrinks, leaving it on the pallet arranged products are stabilized in their position.

When Stretch winder in the prior art so far three basic machine types used. Horizontal, vertical and hood stretcher are known. All basic types use a stretch head that converts one to another Having an axis rotatably mounted film roll, which by means of a guide means within a working space around the loaded pallet is feasible.

Horizontal stretcher have a stretch head, in which the axis of rotation of the film roll is arranged vertically. For example, in US 5,836,140 A Turnteller version described, the loaded pallet rotates on a turntable, while the stretch head is moved vertically in the direction of the axis of rotation of the film roll. The turntable version is relatively inexpensive and is usually a semi-automatic solution.

at the ringers version becomes the vertically arranged stretch head in a horizontal arc move on a rail around the stationary pallet. The rail is moved vertically. The ring traveler always provides a fully automatic Solution.

at the rotary arm version disclosed, for example, in WO 99/42367 A1 the pallet is resting too. The stretch head is here at one Arm attached, which turns around the pallet. The arm has one Rail on which the stretch head in the direction of the axis of rotation of the Film roll is moved vertically. The rotary arm version is also always a fully automatic machine.

A disadvantage of the horizontal stretcher is that the products arranged on the pallet are only fixed laterally on the pallet. It lacks a vertical fixation by pressure from above. In many cases, therefore, the fixation of the products on the pallet leaves something to be desired. In particular, elongated products, such as pipes, can not be stretched horizontally at all. An improvement will be made in DE 41 13 281 A1 achieved with a horizontal stretcher, in which a stamp for holding down the products on the upper side against the products, while a swivel axis perpendicular to the height axis winding around the pallet and the pallet in a relative movement through the ring is performed so that a stretch diagonal over the side surfaces and over the corner edges of the product stack and the pallet, so that this can be done via a fixation in the horizontal and in the vertical direction. However, this requires certain dimensions of the stack on the pallet.

The example in DE 90 12 589 U1 disclosed vertical stretcher is in principle a rotated by 90 ° in the vertical plane ring traveler. The stretch head runs on a vertical ring around the loaded pallet as it is slowly advanced through the ring.

With this stretch winder can in principle processed both very small and very large load heights become. The products are pressed onto the pallet and fixed well.

From The disadvantage, however, is that the vertical stretcher is relatively expensive is because the size of the ring not according to the footprint, but according to the height the palette. For pallet heights over 1,800 mm, the effort disproportionately large. The vertical stretcher requires very big Dimensions, its performance is lower than that of horizontal stretchers.

One Another disadvantage is that for products on the Pallet are easily displaced, an additional fixation of the products is required on the pallet. This leads to a considerable additional effort.

at huge Differences in the loading height the pallet will be an extra Lifting station in the ring required because the pallet only optimal can be stretched when placed approximately in the middle of the ring is. The already expensive in the basic cost machine is still once considerably more expensive.

In US 5,203,139 A Also, a diagonal stretching is achieved via a rotating role in a portal, wherein the stretch head and a vertical linear arm, on which the stretch head is guided, are pivotable.

A combination of a horizontal and a vertical stretchers is in US 5,184,449 A disclosed. In this extensive and complex system, the ring is pivotable between a horizontal and a vertical working position, wherein the loaded pallet is wrapped in two steps, first vertically and then horizontally.

With the hood stretcher, is a prefabricated hood whose dimensions be adapted to the used pallet measure has to be drawn, bigger and over the palette slipped. The restoring forces of Slide down the hood, leaving the slide on the loaded Pallet fits snugly.

The Hoods allow a fixation of different Gutabmessungen and forms. A disadvantage of the hood stretcher is that the hoods relatively expensive and require a complex storage, if different pallet dimensions are to be processed, because every pallet measure one adapted hood requires. It therefore falls relatively high current Costs.

Of the Invention is therefore the object of a generic stretch winder to provide that is less expensive and that in terms of that On the pallet to be fixed Good is universally applicable.

According to the invention solved task solved by that the leadership device is designed as a six-axis articulated robot with which the stretch head with at least three degrees of freedom of movement within a working space around the loaded pallet is, wherein more than two axes of the guide device pivotable are designed.

With A six-axis articulated robot becomes a variable stretch system achieved with both longitudinally and can be stretched horizontally and vertically as well. Since the robot hand with the six-axis articulated robot arbitrarily can move in space, restrictions are limited only by the limited Workspace given by the robot.

Of the Stretch head is attached to the hand of the articulated robot. He can due to the arbitrary programmable path of the robot hand without Additional effort optimally stretches small and large pallets, there any curved Webs, such as both small and large circles, ellipses or ovals, possible are.

Of the Stretch winder according to the invention has the advantage that the stretch head on any, not only a circular one Rail, around the loaded pallet can be driven around. hereby The strength with which the products are fixed on the pallet be significantly improved. With a minimum cost become the advantages of the vertical stretchers with the additional possibility obtained in arbitrarily curved Webs, e.g. any circular or elliptical orbits around the loaded one Being able to drive around the pallet which are limited only by the working space of the stretch winder. Thus, the stretch head of the stretch winder according to the invention around the edges of the loaded Driving pallet in a narrow-radius path, what the tension the film is reduced at these points. The foil can with higher pre-stretch run without a tearing to fear is. The webs of the stretch head around the loaded pallet can be the respective one useful heights customized become. Therefore, the beneficial results of stretching are as well at different loading heights equal.

preferred Embodiments of the stretch head used in the stretch winder according to the invention are Subject of the dependent claims 2 to 4.

Of the Stretch head is usually slidably mounted on a guide arm. The longitudinal displacement on the guide arm forms when using a conventional Four-axis linear robot as a management device the third axis of movement and upon rotation of the guide arm about this axis the fourth (rotation) axis. In a six-axis articulated robot forms the guide arm of the stretch head the seventh (linear) axis.

The free end of the film is, optionally via a pulley, over two Vorreckrollen out, wherein the second, arranged towards the film end roller has a higher peripheral speed as the first roll, causing the film to peel off its free End of the film roll is stretched. In the "power-stretch method" is the pre-stretch between 100 and 300 percent. The Vorreckrollen can through two servomotors or by a drive with a corresponding Gearbox be driven.

at known stretch heads the film occurs on the side opposite the film roll side of the guide arm between two guide rollers out. On this side is preferably a suction device for suction the free end of the film arranged. By switching off the vacuum the film end is released at the beginning of the stretch wrapping process.

After completion of the stretch wrap Ver driving the guide arm is rotated with the stretch head so that the film comes to rest over the suction device and a preferably opposite this welding device. The welding device preferably presses with a spring force against the film and the underlying film layer or film layers and welds the film layers together. A separator arranged between the suction device and the welding device, which may for example consist of a heating wire, separates the film.

by virtue of the holder of the loaded pallet in the wrapping station, so that is around the horizontal surfaces and two opposite vertical surfaces the loaded pallet extending space is free, the film can with the aid of the stretch winder according to the invention around these surfaces be wound easily.

The The object is further achieved by providing a device for stretch wrapping with a stretch winder to wrap a loaded pallet with a slide that has a stretch head with one around an axis having a rotatably mounted film roll and a guide device, a roller conveyor for transporting the loaded pallet to a first wrapping station in the working space of the stretch head and one at the first wrapping station arranged first lifting device with at least two lifting forks, those in openings on a vertical side of the pallet are retractable and with which the pallet can be lifted off the roller conveyor, solved by the management facility is designed as a six-axis articulated robot with which the stretch head with at least three degrees of freedom of movement within a working space around the loaded pallet is, wherein more than two axes of the guide device pivotable are designed. As already described above, offers the Six-axis articulated robot due to its high mobility a number of advantages in stretch wrapping. With the forks of the lifting device, which enter the pallet between the skids or in openings in the runners, The pallet can be raised and held so that the space around the parallel to the forks running sides of the pallet for Vertical stretch in the relevant direction is free and the Do not touch the foil under pressure on the forks. After lowering the Pallet can The forks are therefore easily moved out of the range.

hereby is enabled that the pallet first in the cross direction can be wrapped around the skids, with the forks of the lifting device between the runners and parallel to these are arranged. In connection At the same time, the pallet can move in the longitudinal direction be stretched vertically by removing the forks of the lifting device the foil of the first wrap over the openings pierced in the skids and drive into it. This can be done at the tips of the forks Knife or heating wires to Free cutting of the film may be arranged.

preferred Further developments of the device according to the invention are the subject the claims 6 to 10.

It can use a turntable to turn the pallet in the roller conveyor in Be provided area of the first Umwicklungsstation and the first Lifting device may be arranged in the region of the turntable. in this connection can the palette 90 ° in the horizontal plane are rotated.

The Roller conveyor may preferably be from the first wrapping station extend to a second wrapping station in the working space of the stretch head and at this, a second lifting device with at least two Lifting forks can be arranged, extending in the transverse direction to the Hubgabeln extend the first lifting device. This can be when the pallet is not rotated in two consecutive wrapping stations in transverse and longitudinal direction be stretched vertically.

at the device according to the invention can be provided that on the roller conveyor a station in the work space of the stretch head is provided, in which the film around the vertical Sides of the loaded pallet is windable. For this, the forks the lifting device at the first wrapping station in the longitudinal direction of the roller conveyor (for transverse stretching) and the forks of the lifting device on the second Wraparound station transverse to the roller conveyor (for longitudinal stretching) be arranged. As a leadership institution for the Stretch head an articulated robot is used, this may be due the unlimited possibilities of movement the robot hand between the two in the workspace of the robot located Umwicklungs stations can be arranged.

It For example, a suction device may be provided which acts as a separate sword is formed, which under the pallet, preferably in the middle of the Pallet, is mobile.

Further can the lifting forks of the lifting device have a suction device.

Some embodiments The invention will be described in more detail below with reference to the drawing. In the drawing show:

1 a multifunctional embodiment with turntable,

2 a variant of in 1 illustrated embodiment for cross-stretching,

3 the variant according to 2 for longitudinal stretching,

4 the variant according to 2 for horizontal stretches,

5 a perspective view of a stretch head with guide arm and

6 a schematic cross-sectional view of the stretch head with guide arm.

1 to 4 show the use of a six-axis articulated robot as a stretch winder 17 , As from the drawing, eg 1 , points out, features the stretch winder 1 for wrapping a loaded pallet 2 with a foil 3 a stretch head 4 and a guide device 5 on, with the the stretch head 4 with at least three degrees of freedom of movement within a working space around the loaded pallet 2 can be guided, with more than two axes of the guide device are designed to pivot.

The stretch head 4 has one around an axis 6 rotatably mounted film roll 7 on, from which the foil 3 for wrapping the pallet 2 is deducted. The stretch head 4 will be explained below on the basis of 5 and 6 described in more detail.

How to continue 1 shows, is to transport the loaded pallet 2 a roller conveyor 11 with a turntable 12 intended.

The pallet 2 gets over the roller conveyor 11 in conveying direction F on the turntable 12 promoted. On the guide device 5 for the stretch head 4 opposite side of the turntable 12 is a lifting device 13 with two lifting forks 14 intended. The lift forks 14 have initially moved back. The turntable 12 turns the palette 2 around 90 °. The lift forks 14 then drive into the space between the runners 15 the pallet 2 and lift them into the machining position.

Then the stretch head moves 4 controlled by the guiding device 5 , Under the pallet and passes the beginning of film to vacuum suction cups, not shown in the drawing, which under the Hubgabeln 14 are arranged. The pallet 2 is then wrapped in its original transverse direction. After wrapping, the end of the film can be welded and severed, as will be described later. The foil 3 but also with the stretch head 2 remain connected and continue to be used for the subsequent longitudinal winding without a fresh start.

After the transverse winding, the pallet is moved by the lifting device 13 back on the turntable 11 lowered. The lift forks 14 drive out of the pallet 2 out. The pallet 2 is then rotated back on the turntable 11 by 90 °. The lift forks 14 then drive into openings in the skids. So that's about the runners 15 extending cross winding can be pierced clean are at the tips of the lift forks 14 not shown in the drawing, knives or heating wires mounted for cutting free.

The pallet is from the lifting device 13 back to the working position, as in 1 is shown raised. A wrapping in the original longitudinal direction of the pallet 2 is applied.

The transverse process of the stretch head 4 can be done either via the axis D of the articulated robot or by the Hubgabelweg F.

The end of the film is, as will be described later, welded and the stretch head 4 separated.

The transverse and longitudinal winding of the pallet 2 happens analogous to that in 1 illustrated embodiment. The transverse process when stretching can also be done here either on the axis D of the articulated robot or on the Hubgabelweg F.

Due to the articulated robot, in addition to the vertical transverse and longitudinal stretching an in 4 shown horizontal stretching can be made. Thanks to its freely programmable path, the robot stretcher can optimally stretch small and large pallets.

2 shows the use of as a stretch winder 17 used articulated robot at two consecutive wrapping stations. Due to its multifunctionality, the articulated robot can be used between the two wrapping stations. The pallet 2 gets over the roller conveyor 11 transported to the first wrapping station. There is the lifting device 13 arranged so that the lift forks 14 lie close to the rollers on which the pallet 2 comes to a stop. The lift forks 14 grab like a pallet truck in the space between the runners of the pallet 2 and lift them into the working position. The stretch head 4 starts under the pallet 2 with the transfer of the film beginning on in the Hubgabeln 14 built-in vacuum cleaner. It then becomes the transverse winding on the pallet 2 applied. The end of the film can be welded and separated, but on the other hand it can also be used with the stretch head 4 stay connected, so that afterwards in the second wrapping station takes place longitudinal winding without restart of the film can begin. The lifting device 13 lowers the pallet 2 on the roller conveyor 11 for further transport to the second wrapping station.

While the transverse winding by the articulated robot in 2 is shown, the longitudinal winding goes out 3 out.

Is the foil 3 After the cross-winding has been separated, it can have a not shown in the drawing sword with vacuum suction openings from the stretch head 4 be taken over. Then the longitudinal winding begins. After wrapping, the vacuum on the blade switches off and switches to compressed air. This will release the film 3 from the sword. At the same time, the sword returns. Repeated wrapping in the longitudinal direction completes the longitudinal winding. The film end is welded and separated, as already described above.

The pallet 2 finally gets through the lift forks 14 lowered and on the roller conveyor 11 removed.

If a vertical stretching is also to be performed after the vertical stretching, the palette becomes 2 this in a corresponding work area, according to 4 between the first and second wrapping station, proceed.

The arm of the robot drives the stretch head 4 down and so can the palette 2 drive around and wrap horizontally.

In the 5 and 6 is the stretch head 4 shown in more detail.

The stretch head 4 is about a leadership profile 18 on a guide arm 10 , which forms a robot arm or is arranged on such a displaceably mounted. The displacement effecting drive is a standard drive and not shown in the drawing.

The stretch head 4 consists essentially of a film roll 7 that have a bracket 19 around an axis 6 is rotatably mounted on the stretch head, two Vorreckrollen 20 and 21 with which the film 4 when wrapping the pallet is stretched, three rolls 22 . 23 and 24 for the film guide and a combined suction, separation and welding device 25 . 26 and 27 ,

When inserting a new film roll 7 will be the free end of the slide 3 over the suction device 25 placed essentially on the roll of film 7 opposite side of the guide profile 18 of the stretch head 4 is arranged. In addition to the suction device 25 and others from the roles 23 and 24 opposite sides is a separator 26 provided, for example, may consist of a heating wire. The heating wire is briefly switched to disconnect the film, so that only a short end of the film 3 remains. The stretch head 4 is then able to work.

The one of the roles 23 and 24 opposite side of the suction and separation device 25 . 26 runs on the stretch head 4 angled and has the welding device 27 on.

When using the stretch head 4 runs between the two roles 23 and 24 slide out of the stretch head as in 6 by 3a shown. If the end of the film after working on the pallet 2 welded and separated, the stretch head turns 4 , eg by about 135 °, from the pallet 2 away, leaving the slide as in 6 by 3b shown runs. The welding device presses 27 by means of a spring device, not shown in the drawing, against the film 3b on the stretched pallet 2 , The multiple foil windings are welded at this point. Thereafter, for example, separates the separator consisting of a heating wire 26 the foil off.

Through the suction device 25 the foil end is held. The stretch head 4 The foil can then be attached to a new palette 2 at the transfer point, eg the lift forks 14 or a sword.

The pre-stretching of the film by the two Vorreckrollen 20 and 21 can be set at different speeds on the two rollers. The two roles 20 and 21 can be driven by two servomotors or by a drive with a corresponding gear step.

As not shown in the drawing, the Hubgabeln can 14 consist of closed tubes. In the tubes, one or more rows of holes may be mounted on the bottom, the length of which is slightly shorter than the width of the film 3 is. will the film 3 to the bottom of the lift forks 14 created and the pipes connected to a vacuum, so the film is through the Hubgabeln 14 sucked and held. To release the film, the vacuum is switched off and compressed air is added to the pipes.

Alternatively, on a lifting fork 14 a separate suction / blowpipe are attached.

In another embodiment, the lifting forks 14 also consist of a closed tube. On the bottom of one or more rows of holes are arranged over the entire length of the pallet width. Alternatively, on a lifting fork 14 be arranged a separate blow-off. By blowing compressed air into the pipe, the film is when retracting the lift forks 14 separated from the lift forks. This will adhere the film 3 on the lift forks 14 prevented.

Instead of the lifting forks 14 can also be a separate sword with vacuum suction provided. The sword also has one or more rows of holes over a length slightly shorter than the foil width. The sword is used to hold the beginning of the film at the beginning of the winding process.

The sword is preferably on the side of the roller conveyor 11 arranged at which the lifting device 13 located. At the beginning of a longitudinal stretching the sword moves centrally under the raised pallet, so that the stretch head 4 can pass the beginning of the film there.

The return method of the transversely driven lifting forks 14 for lifting the pallet 2 is facilitated with a belt, not shown in the drawing, below the lift forks 14 is arranged.

1

Stretch winders

2

palette

3

foil

3a

foil

3b

foil

4

Stretch head

5

guide means

6

axis

7

film roll

8th

guiding device

9

guiding device

10

guide

11

roller conveyor

12

turntable

13

lifting device

14

fork

15

skids

16

openings

17

Stretch winders

18

guide profile

19

bracket

20

Vorreckrolle

21

Vorreckrolle

22

role

23

role

24

role

25

suction

26

separator

27

welding equipment

D

axis

e

conveying direction

F

Hubgabelweg

Claims (10)

Stretch winder ( 17 ) for wrapping a loaded pallet ( 2 ) with a foil ( 3 ), with a stretch head ( 4 ), one around an axis ( 6 ) rotatably mounted film roll ( 7 ), and a guide device ( 5 ), characterized in that the guide device ( 5 ) is designed as a six-axis articulated robot with which the stretch head ( 4 ) with at least three degrees of freedom of movement within a working space around the loaded pallet ( 2 ) is guided, wherein more than two axes of the guide device ( 5 ) are designed pivotable. Stretch winder ( 17 ) according to claim 1, characterized in that the stretch head ( 4 ) a suction device ( 25 ) for sucking the free end of the film ( 3 ) having. Stretch winder ( 17 ) according to claim 1, characterized in that the stretch head ( 4 ) a separating device ( 26 ) for separating the film ( 3 ) except for a short end. Stretch winder ( 17 ) according to one of claims 1 to 3, characterized in that the stretch head ( 4 ) a welding device ( 27 ) for welding the around the loaded pallet ( 2 ) wrapped foil ( 3 ) having. Device for stretch wrapping with a stretch wrapper ( 17 ) for wrapping a loaded pallet ( 2 ) with a foil ( 3 ), which has a stretch head ( 4 ) with one around an axis ( 6 ) rotatably mounted film roll ( 7 ) and a leadership facility ( 5 ), a roller conveyor ( 11 ) for transporting the loaded pallet ( 2 ) to a first wrapping station in the working space of the stretch head ( 4 ) and a first lifting device arranged at the first wrapping station (US Pat. 13 ) with at least two lifting forks ( 14 ) in openings ( 16 ) on a vertical side of the pallet ( 2 ) are retractable and with which the pallet ( 2 ) from the roller conveyor ( 11 ), characterized in that the guide device ( 5 ) is designed as a six-axis articulated robot with which the stretch head ( 4 ) with at least three degrees of freedom of movement within a working space around the loaded pallet ( 2 ), wherein more than two axes of the guide device (s) ( 5 ) are designed pivotable. Apparatus according to claim 5, characterized in that a turntable ( 12 ) for turning the pallet ( 2 ) in the roller conveyor ( 11 ) is provided in the region of the first wrapping station and the first lifting device ( 13 ) in the area of the turntable ( 12 ) is arranged. Apparatus according to claim 5, characterized in that the roller conveyor ( 11 ) from the first wrapping station to a second wrapping station in the working space of the stretch head ( 4 ) and at this a second lifting device ( 13 ) with at least two lifting forks ( 14 ) is arranged, which in the transverse direction to the Hubgabeln ( 14 ) of the first lifting device ( 13 ). Device according to one of claims 5 to 7, characterized in that on the roller conveyor ( 11 ) a station in the working space of the stretch head ( 4 ) is provided, in which the film around the vertical sides of the loaded pallet ( 2 ) is windable. Device according to one of claims 5 to 8, characterized by a suction device which is designed as a separate sword, which under the pallet ( 2 ) is mobile. Device according to one of claims 5 to 8, characterized in that the lifting forks ( 14 ) of the lifting device ( 13 ) have a suction device.