EP1597147B1

EP1597147B1 - A method and a system for wrapping objects and use of the method

Info

Publication number: EP1597147B1
Application number: EP04713516A
Authority: EP
Inventors: Poul Blom Petersen
Original assignee: Seelen AS
Current assignee: Seelen AS
Priority date: 2003-02-24
Filing date: 2004-02-23
Publication date: 2007-02-07
Anticipated expiration: 2024-02-23
Also published as: US20060053750A1; DK1597147T3; DE602004004634T2; WO2004074105A1; EP1597147A1; DK176023B1; DE602004004634D1; ATE353307T1; DK200300278A

Abstract

The invention involves a method and a system and use of the method for wrapping one or more objects ( 6 ) in stretch film, said film ( 1 ) comprising a tube-like section, the diameter of which is smaller than the diameter of the object or objects to be wrapped, said film comprising a first end ( 2 ) and a second opposite end ( 4 ), wherein the film is opened at its first end and provided with a number of folds transversally of its longitudinal axis, following which the film is expanded diametrically. Novel aspects comprise that the object or objects are supported and advanced essentially horizontally or under a flat angle in relation to the horizontal into the expanded film from the first free end thereof towards the second end of the film, which other end is closed, following which the film is pulled around the object or objects the folds of the film being unfolded, until the entire object or objects is/are introduced into the film, following which the first end of the film is closed by joining for complete enclosure of the object or objects in the film. Hereby, compared to the prior art, it is accomplished that the object or objects is/are enclosed on all sides and hence completely.

Description

The invention relates to a method of wrapping one or more objects in stretch film according to claim 1. The invention also relates to a system of carrying out the method according to claim 11. Moreover, the invention relates to a use of the method, according to claim 18.
It is already known to wrap objects in stretch film. US 4,050,219, DE 2,706,955, DE 3101310 and EP 0 344 815 A1, teach processes, wherein a tubular film having smaller circumferential dimension that the object to be wrapped is shifted down over and arranged in folds on a stretching unit, following which the end of the film is closed by welding, whereby a bag is formed whose bottom faces upwards. The film is subsequently expanded horizontally and pulled vertically down over a number of items stacked on a pallet. In proximity of or underneath the pallet the film is let go. By this wrapping the items are stabilised on the pallet, the film remaining, following application, to a certain extent tensioned, and likewise a certain degree of coverage and protection are also imparted to the items.
US 5 467 576 discloses a method according to the preamble of claim 1.
The thus known processes for wrapping are associated with the exemplary weakness that the side facing towards the pallet remains unprotected. It follows that the objects are not fully wrapped and are therefore able to absorb moisture, smell and the like. The objects being arranged on the pallet, which is in turn sitting on a support, it is not possible to convey the film underneath the pallet and close it off completely. It is a further aspect that the processes are not suitable for objects that are not arranged on a pallet or some other carrier means. The underside(s) of the lowermost object(s) will thus be fully exposed. Moreover there is a risk of the objects falling out of the wrapping from below.
Novel aspects of the method according to the invention comprise that the object or objects are supported and advanced essentially horizontally or under a flat angle relative to the horizontal into the expanded film from its first open end towards the second end of the film, following which the film is pulled around the object or objects, the folds of the film being unfolded until the entire object or objects are introduced into the film, following which the first end of the film is closed by joining for complete enclosure of the object or objects in the film.
Hereby, compared to the prior art, it is accomplished that the object or objects are enclosed to all sides and hence completely. Thereby it is also accomplished that the objects need not be arranged on a pallet or the like to avoid contact with a support on which the wrapped object(s) is/are arranged.
According to a preferred embodiment the film may, during advancement of the object or objects within the film, be arranged at a space between a first and a second support, where the object or objects is/are, during the advancement, moved from the first to the second support. In this manner the object or objects may remain essentially supported during the entire movement, including in particular if the objects are long compared to the expanse of the space.
According to an alternative embodiment the object or objects can be arranged on the first support and seized with seizing means, following which the object or objects are introduced into the film and arranged on the second support, following which the object or objects is/are let go.
According to yet an embodiment at least the first support may comprise means for displacing the object or objects. This is advantageous as the object or objects are to be moved from the first to the second support. Thus, the means for displacement need only eg push the object or objects.
According to a preferred embodiment the first support may be displaceable or comprise a displaceable section, wherein the first support or section is displaced and introduced into the expanded film for further support of the object or objects during movement from the first to the second support. Thereby the object or objects can be supported during a larger part of the movement between the first and the second support. That may be advantageous when relatively short objects are wrapped.
According to yet a preferred embodiment the film may be tensioned for tightening when being pulled around the object or objects. Hereby less film is used and, likewise, the film becomes tidy and smooth. When a number of objects are wrapped simultaneously, the film will also support the objects. If the load is increased and imparts a permanent increase in length to the film, further film savings are obtained and the supporting effect is enhanced. It is also obtained that objects having a tendency to shrink will remain tightly wrapped and hence stable as the film will follow the shrinkage due to its tensioning.
According to yet a preferred embodiment the first, the second and the further support may be roller paths and/or conveyor belts. This enables easy incorporation of the method in connection with production plants where the objects are transported by those types of transporter means.
Joining may advantageously be accomplished by welding which yields a quick and reliable result.
According to yet an embodiment the object or objects may be arranged on a carrier means such as a pallet. It may be practical in case of stacked objects or objects that are otherwise difficult to move.
The film may be dispensed from a storage unit from where it is cut to a suitable length and closed at its other end by joining prior to folding. Thereby the film may be eg in roller shape, which saves place. Otherwise pieces of film manufactured in advance can be used, that have already been shortened and closed at the one end.
The film on the storage unit can be provided with longitudinally extending folds that reduce the width of the film. Thereby welding gussets used for joining the film need not be so wide.
Novel aspects of the system according to the invention comprise that the system comprises means for supporting and advancing, essentially horizontally or at a flat angle in relation to the horizontal, the object or objects through the stretching unit with the film in expanded state for pulling of the film around the object or objects and complete introduction of it or them into the film and means for closing or joining the first end of the film for complete enclosure of the object or objects in the film.
According to a preferred embodiment the system may comprise a first roller path from where the object or objects is/are advanced to the stretching unit, a displaceable roller path section that can be displaced into the stretching unit when the latter has expended the film and a second roller path for receiving the object or objects. Thereby the system is readily integrated into production plants where objects are transported in a similar manner. By the displaceable roller path section the object or objects are supported to a large extent.
According to a preferred embodiment the system may comprise means for dispensing film from a storage unit.
According to a further preferred embodiment the system may also comprise means for welding and means for cutting off the film, which means are displaceable and arranged after the stretching unit.
According to yet an embodiment the stretching unit may comprise operated rollers for winding film, which rollers will, during pulling of the film around the object or objects, form holding-back means. Also the rollers may contain means measuring the angulation, including encoders, whereby it is possible to measure and control how much film is introduced onto the stretching unit.
Novel aspects of the use of the method comprise that one or more objects are wrapped, which objects are essentially flat and elongate, and wherein the object or objects are wrapped with the longitudinal axis situated in parallel with an axis extending between the first and the second ends of the film,
In the following the invention will be described in further detail with reference to figures that illustrate examples of embodiments of the invention. The technique is given in a simplified manner to emphasize the novel aspects of the invention. Other structural details will be known to the person skilled in the art and will appear ia from US 4050219, DE 2706955, DE 3101310 and EP 344815 A1.

Figures 1-5: show schematic cross-sections of a system according to one embodiment of the invention. The figures teach ia an example of a wrapping procedure;
Figures 6-7: teach schematic cross-sections of a system according to an alternative embodiment of the invention.

Figures 1-7 show a number of objects 6 that are to be wrapped in a tubular film 1. Also one single object 6 may be wrapped and, likewise, two or more objects, including stacked objects and objects arranged on a carrier means, may be wrapped. Preferably the film 1 has an expanse which is smaller than the expanse of the objects 6. The figures show a frame structure 26 that carries the various components, including miscellaneous guide means, etc, that partake albeit they are not shown; that may, however, readily be exercised by the person skilled in the art as they present common knowledge within the prior art wrapping techniques and appear from the above-referenced respective documents.
Figure 1 shows the film 1 that is dispensed from a storage unit 8, from where it is conveyed to a distributor head 22 that is, by means of a suction discs, able to open the film 1 at the first end 2 thereof, when the latter is to be conveyed onto a stretching unit 10. The distributor head 22 is movable and comprises means for conveyance of the opened film 1 into or across the stretching unit 10. On the stretching unit 10 the film 1 is arranged in a number of folds to occupy as much space as possible in the horizontal direction. To assist movement of the film 1 the stretching unit may comprise operated rollers 20, which rollers may also form holding-back means when the film 1 is to be applied to the object or objects 6 when the film 1 is pulled off the stretching unit 10.
In figures 1-5 a first roller path 12 is shown that has a displaceable roller path section 15, and a second roller path 14. Roller paths are suitable for use in connection with the wrapping, but conveyor belts are also suitable. The roller paths 12 and 14 can be completely or partially operated. If the roller path 12 is not operated, the objects 6 can be pushed, eg by means of a pneumatic cylinder to produce a desired movement. Moreover, Figures 1-5 also show means for welding 16 and means for cutting 18.
In figure 2 a suitable length of film 1 is arranged on the stretching unit 10, and means for welding 16 join the film 1, following which means for cutting 18 separate the piece of film on the stretching unit 10 from the remainder of the film.
Figure 3 shows that the distributor head 22 is displaced upwards in order for it to be clear of the path of the objects 6 during the wrapping, but it may just as well be displaced sideways. Means for welding 16 are also taken to clear positions. By joining, see Figure 2, the clear film on the stretching unit is provided with a closed end 4, following which the film is expanded by the stretching unit. During application of the film on the stretching unit, it is pulled together, whereby the film is easily displaced there across. By the expansion the circumferential dimension of the film becomes diametrically larger than the objects 6. The displaceable roller path section 15 is displaced into the stretching unit 10 and into the expanded film. Between the roller path 12 (and the section 15) and the roller path 14 a space 24 is provided that allows the film to come from the underside of the roller path section 15 and up on the top face of the roller path 14.
Figure 4 shows how the film 1 is pulled off the stretching unit 10 and pulled around the objects 6. The rollers 20 form holding-back means whereby the film 1 is stretched suitably and preferably tensioned to the effect that it is situated tightly longitudinally of the objects. Holding-back means can be accomplished in other ways without use of rollers, eg with a fixed back edge that yields frictional resistance. The film 1 may also be pulled with more tension, whereby a permanent increase in length is imparted thereto. When the film 1 is pulled around the objects 6, the film maintains a certain tensioning whereby the objects are stabilised. A part of the tensioning compresses the stack of objects 6 and thereby follows the objects should they settle during transport or storage and, likewise, the pressure presses the objects towards each other and hence creates mutual friction that further contributes to stabilisation.
In Figure 5 the objects 6 have been conveyed entirely into the film, and the first end 2 has been closed by joining by means for welding 16. This may be controlled in that - immediately preceding release of the end 2 of the film from the rollers 20 - means for welding 16 are conveyed towards each other and join the film. If necessary, excessive film 1 can be cut off. Prior to joining the roller path section 15 can be withdrawn and the stretching unit be pulled together, and likewise the film can be released from the rollers 20 to thereby minimise the amount of excessive film following the joining. It is noted that the same means for welding 16 can be used for joining both the first end 1 and the second end 4 of the film 1. The objects 6 are now completely wrapped. When the objects 6 have been removed, the roller path section 15 can be withdrawn, the stretching unit 10 pulled together, and the distributor head 22 can be lowered down in front of the stretching unit, whereby the system is back to its starting situation, see Figure 1, and renewed wrapping can be commenced.
Figure 6 shows an alternative embodiment wherein a stretching unit 10 is applied with film 1 corresponding to Figure 1, but with the difference that the stretching unit 10 can be moved vertically and as shown receives the film 1 in a raised position. Hereby improved space is accomplished around the stretching unit 10 for miscellaneous functional means, whereby the film 1 is more readily applied to the stretching unit. Thus, the distributor head 22 can be stationary, while means 16 for welding the film 1 for forming a closed end 4 are vertically movable, and including also adaptation for closure of the open end 2 of the film following wrapping of an object. Figure 7 shows the stretching unit 10 in a lowered position, which corresponds to the situation shown in Figure 2. Now the film 1 must be expanded by the stretching unit 10, corresponding to Figure 3, following which the wrapping can be implemented, see Figures 3, 4 and 5. In this context, too, the vertically movable means 16 for welding are configured to close the end 2 of the film 1, whereby complete wrapping is accomplished.
The figures show the use of roller paths, but movement of the object or objects 6 can be accomplished in numerous ways. All it takes are two supports (locations), between which the expanded film 1 is arranged. Then the objects 6 can be moved, eg pushed by means of piston, from the first to the second support, eg sliding on the supports. Also the objects 6 can be seized with seizing means, eg configured as a set tweezers or a claw or be taken by means of forks like the forks of a forklift truck and conveyed from one support to the other. The fundamental principle is that the objects 6 are conveyed, while being supported, into the expanded film 6, where the latter is pulled around the objects 6. Depending on the length and rigidity (and nature in general) of the objects 6, the supports may be arranged with a given space there between without tilting downwards. If that is a problem, a displaceable support or part of the support, eg like a tongue, is conveyed to a position to minimize said space.
Objects 6 may be of different lengths and yet be wrapped with the same film and stretching unit 10. The length may be controlled by measuring how much film 1 is arranged on the stretching unit. It can be accomplished ia by providing the rollers 20 with encoders.
It will be understood that the invention as described in the present description and figures can be modified or changed and continue to be comprised by the scope of protection of the patent claims that follow.

Claims

A method of wrapping one or more objects (6) in stretch film, which film (1) comprises a tube-like section, the diameter of which is smaller than the diameter of the object or objects (6) to be wrapped, which film (1) comprises a first end (2) and a second opposite and closed end (4), wherein the film (1) is opened at its first end (2) and provided with a number of folds transversally of its longitudinal axis, following which the film (1) is expanded diametrically, wherein the object or objects (6) is/are conveyed by roller paths and/or conveyor belts (12, 14), essentially horizontally or under a flat angle in relation to the horizontal, into the expanded film (2) from its first end (2) towards the second end (4) of the film, following which the film (1) is pulled around the object or objects (6) as the folds of the film are unfolded, until the entire object or objects (6) have been introduced into the film (1), following which the first end (2) of the film is closed by joining for complete enclosure of the object or objects in the film, characterised in that the film (1) is, during advancement of the object or objects (6) in the film, arranged at a space between the first (12) and the second (14) roller paths and/or conveyor belts, and wherein the object or objects are conveyed from the first (12) to the second (14) roller paths and/or conveyor belts.
A method according to claim 1, characterised in that the object or objects (6) are arranged on the first roller paths and/or conveyor belts (12) and seized by seizing means, following which the object or objects are introduced into the film (1) and arranged on the other roller paths and/or conveyor belts (14) following which the object or objects are let go.
A method according to one or more of the preceding claims, characterised in that the first roller paths and/or conveyor belts (12) is displaceable or comprises a displaceable section (15), wherein the first roller paths and/or conveyor belts (12) or section (15) is displaced and introduced into the expanded film (1) for further supporting the object or the objects (6) during movement from the first (12) to the second (14) roller paths and/or conveyor belts,
A method according to to one or more of the preceding claims, characterised in that the film (1) is tensioned for tightening when being pulled around the object or objects (6).
A method according to claim 4, characterised in that the tensioning imparts a permanent increase in length to the film (1).
A method according to claim 3, characterised in that the section (15) comprises, roller paths and/or conveyor belts.
A method according to claim 1, characterised in that the joining is accomplished by welding.
A method according to one or more of the preceding claims characterised in that the object or objects (6) are arranged on a carrier means such as a pallet.
A method according to one or more of the preceding claims, characterised in that the film (1) is dispensed from a storage unit (8), from where it is cut to a suitable length and closed at its second end (4) by joining prior to folding.
A method according to claim 9, characterised in that the film (1) on the storage unit (8) is provided with longitudinally extending folds that reduce the width of the film.
A system of exercising the method according to one or more of claims 1-10, wherein one or more of the objects (6) are wrapped in stretch film, said film (1) comprising a tube-like section, the diameter of which is smaller than the diameter of the object or objects (6) to be wrapped, which film (1) comprises a first end (2) and an opposite and closed end (4), wherein the system comprises means for opening (22) the film at its first end and means for moving (20, 22) the film across a hollow stretching unit (10) and providing the film with a number of folds transversally of its longitudinal axis, said stretching unit (10) comprising means for expanding the film diametrically and means for forming holding-back means (20) while the film is being released, wherein the system comprises roller paths and/or conveyor belts, (12, 14) for conveying, essentially horizontally or under a flat angle in relation to the horizontal, the object or objects (6) through the stretching unit (10) with the film (1) in expanded state for pulling the film (1) around the object or objects (6) and completely introducing it or them into the film (1), and means for closing and joining (16) the first end (2) of the film for complete enclosure of the object or objects (6) in the film characterised in that said roller paths and/or conveyor belts (12, 14) comprise a first (12) and a second (14) roller paths and/or conveyor belts wherein the film (1), during the conveying of the object or objects (6) in the film, is arranged at a space between said first and a second roller paths and/or conveyor belts (12. 14), and wherein the object or objects are conveyed from the first (12) to the second (14) roller paths and/or conveyor belt.
A system according to claim 11, characterised in that the first roller path and/or conveyor belt (12) is displaceable or comprises a displaceable section (15), wherein the first roller path and or conveyor belt (12) or section (15) is displaced and introduced into the expanded film (1) for further supporting the object or the objects (6) during the conveying from the first (12) to the second roller paths and/or conveyor belt.
A system according to any of the claims 11 - 12, characterised in that said displaceable section (15) comprises roller paths and/or conveyor belts.
A system according to any of the claims 11 - 13, characterised in that the system comprises means for dispensing film from a storage unit (8).
A system according to one of claims 11-14, characterised in that the system comprises means for welding (16) and means for cutting off (18) the film, said means being displaceable and arranged after the stretching unit (10).
A system according to one or more of claims 11-,15, characterised in that the stretching unit (10) comprises operated rollers (20) for winding of film (1), said rollers forming holding-back means when film is pulled around the object or objects (6).
A system according to claim 16, characterised in that the rollers (20) comprise means for measuring angulation, including encoders.
Use of a method according to one or more of claims 1-10 or a system according to one or more of claims 11-17 for wrapping one or more objects (6), said objects (6) being essentially flat and elongate, and wherein the object or objects (6) are wrapped with the longitudinal axis situated in parallel with an axis extending between the first end and the second end (2,4) of the film.