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(11) | EP 0 029 419 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A strip of protecting covers for cargo units, and a device for applying such covers |
| (57) When manufacturing protecting covers of shrinkable plastic foil having a pleated
portion along at least one of its sides, welding seams (14b, 14c) are arranged individually
in the pleats (16, 17) so no welding seam will interconnect more than two layers of
foil. The covers are manufactured in a long series, separated by tear-off lines (15)
and are rolled or folded into a magazine. When feeding-out covers from the latter an expandable folding-out device (18) runs within the pleated portion, which may occur continuously from cover to cover due to the individual welding seams (14b, 14c) at the pleats. The devices (18) may be brought to grip the foil and also to expand the pleats so the cover will be opened. Further devices (19) are arranged to grip the lower portion of the cover to open the latter fully and to pull the cover down along a cargo unit (20). |
[0001] In order to protect and to support cargo which is stacked upon a pallet, or some similar carrier, a protecting cover, usually manufactured of shrinkable plastics foil, is often used, the cover, like an inverted sack being pulled down over the substantially prismatic cargo unit. The cover may be manufactured from a flattened tube, or from a folded sheet, and is produced in a series, where the individual covers hang together in an elongate strip, which may be rolled or folded into a magazine.
[0002] Experience has shown, that it is difficult to separate the different layers of foil in the cover, so the mouth will be sufficiently open to permit the initial mounting upon the cargo unit. This has, in practice, prevented the use of mechanical mounting aids.
[0003] The aim of the present invention is to propose a method of manufacturing protecting covers, which are provided with a pleated portion along at least one of its sides, and intended to be opened by mechanical means. The invention also includes a device for applying such protection cover upon a cargo unit.
[0004] A method according to the invention is characterized in welding the foil along a seam extending to the inward base of the pleated portion (or portions, respectively), and thereafter welding the foil in each side of the pleated portion by individual seams, so no welding seam will interconnect more than two layers of foil. Preferably the individual welding seams at the pleated portions are arranged obliquely in relation to the welding seam running transversely in relation to the pleated portions and interconnecting the foil at the central portion of the cover, and with covers produced in an elongate strip, tear-off lines are made to follow the welding seams in the pleats.
[0005] A noticeable drawback when applying a protecting cover is that a volume of air is entrapped in the cover. This air will expand during the heat shrinking operation, and will blow up the cover. The latter is therefore, advantageously provided with evacuation openings at its upward end. Such openings can preferably be obtained by stopping the individual welding seams at the pleats short of their outward edges to leave air evacuating openings along the latter.
[0006] A device according to the invention comprises a magazine containing a series of covers formed into a strip and along at least one side being provided with a pleated portion, in which the individual-covers are severable along tear-off lines and are welded so seams run individually along the sides of the pleated portions and further including means adapted to be introduced into said pleated portion, or portions, and during feeding-out of the strip to follow the pleated portion and, during a tearing-off operation, to grip each side of a pleated portion at the sides directed away from each other.
[0007] Further means are preferably adapted to engage the margin of the cover remote from the welding seams and to bring the engaged portions outwardly, to straighten-out the pleated portion. The first mentioned means, causing the primary unfolding of the pleated portion,preferably comprises a wedge-shaped member having two wings foldable along a central ridge, as well as a finger running outside of each pleat and engageable with the wedge-shaped member.
[0008] The further means being provided to bring the cover margin remote from the welding seams outwardly preferably comprises hook-members operating in pairs and connected to a common actuating device. Each hook-member is preferably formed as a clamping claw and is mounted in a guide permitting a vertical displacement along the cargo unit.
[0009] Some embodiments of the invention will below be described with reference to the accompanying drawings, in which
Figure 1 schematically shows the working of the device,
Figure 2 on a larger scale, shows the action at the members opening the cover,
Figure 3 shows a perspective view of a folding out means, as seen from outside the cover,
Figure 4 shows the folding out means as seen from above and in folded-together position,
Figure 5 shows the folding out means, as seen from above, in expanded position,
Figure 6 shows opening-out means arranged in pairs,
Figure 7 and 8 show components of the opening-out means in open and closed position, respectively,
Figure 9 shows a portion of a flattened tube between two covers,
Figure 10 shows a flattened tube according to Figure 9 pulled down over a cargo unit, but before the shrinking, and
Figure 11 shows a portion of a flattened tube between two covers of a design somewhat modified in relation to that according to Figure 9.
[0010] Protecting covers intended to be used with goods stacked upon a pallet are usually manufactured from a flattened tube of plastics, or from a sheet of plastics foil, folded along a center line. The tubeJor the foil, respectively, is continously fed out and the individual covers are produced by welding seams and tear-off indications being arranged transversely to the feeding-cut direction. In order to make the cover fit snugly over the prismatic unit into which the goods have been formed, the cover is provided with a pleated portion, which in a cover made from a folded sheet will be located along the top of the cover. A cover manufactured from a flattened tube will have two pleated portions, located opposite to each other, along vertical sides of the cover.
[0011] In known embodiments the transverse welding seams have been arranged in such a manner, that they have interconnected all layers in the sheet, or in the tube, respectively, i.e. the pleated portions have also been interconnected. This has made it impossible for mechanical opening means to include some member projecting between the pleats and following the same during the feeing-out from the magazine.
[0012] A first step according to the present invention is thus to arrange the welding seams at the individual pleats so they are separated from each other, which means that no welding seam will be permitted to interconnect more than two layers of material. This may for instance be obtained by introducing a heat insulating partition between the pleats during the welding operation.
[0013] The manufacture of covers in long series is well konwn by itself, and need not be described in detail or illustrated. It is only necessary to remember that during the welding operation an extra step is to be taken to prevent the pleats being interconnected.
[0014] Figure 1 shows very schematically the operation of taking a cover from a magazine and pulling it down over a cargo unit. The magazine 10 is very schematically illustrated, and supposedly contains a series of covers made from a flattened tube, the covers being separated by welding seams and tear-off perforated lines. The figure schematically indicates covers 11, 12, 13 being fed out. They are separated by transverse welding seams 14 and tear-off lines 15. The welding seams between covers 12 and 13 are shown distinctly. There is a central seam 14a, which interconnects the material between the pleats and individual seams 14b and 14c interconnecting the material in the individual pleats in the pleated portions 16 and 17, formed along the longitudinal margins of the flattened tube.
[0015] The fact that the pleated portions 16 and 17 run continously from one cover to the following makes it possible to use folding out means 18, which all the time operate within the pleated portions. In the manner to be described more in detail in connection with Figures 2-5 these means may be used, during a tearing-off operation, to unfold the pleated portions 16, 17 in a movement, which initiates an opening of the mouth of the cover. Hereby opening means 19, the design and function of which will be explained in connection with Figures 6-8, can be applied and may be used for pulling the cover down over a cargo unit 20.
[0016] Figure 2 shows, on a somewhat enlarged scale, a portion around the tear-off line 15 between two covers 12 and 13. For the purpose of explanation two superposed folding-out means 18 are shown indifferent positions, but it is to be understood that two folding out means are actually provided in juxtaposed positions, and that the covers are pulled past these means. In the upper position illustrated in Figure 2 the means 18 is folded together, as will be explained in connection with Figures 3-5. The means 18 includes a wedge-shaped head, which projects into the adjacent pleated portion and comprises two wings 21, which are hinged together along an upper central ridge 22. Actuators 23, not shown in detail, can make the wings expand, as is shown in the lower position in the middle of Figure 2, where the wings have forced apart the pleats forming the portion 16. This spreading-out of the pleats will continue downwardly to the lower mouth of the cover, and makes it possible for opening means 19, formed as arms having hooks at their ends, to be brought into the pleats and to further expand the mouth of the cover. Two arms 19 are interconnected by toothed segments 24, so they will move in unison.As will be evident from the description in connection with Figures 6-8 the means may include claw devices, which grip the material in the cover, and may be used to pull the same down over the cargo unit 20.
[0017] Figure 3 shows, more in detail but still very schematically how a folding out means 18 is built up. The two wings 21 are, as mentioned above, interconnected by a hinge 22 formed as a central ridge. Outside the wings there are two fingers 30, which are also operated by actuators 23, and which may be brought to clamp their tips 31 against the foil material at the outer sides of the pleats, thereby to retain the cover. Figure 4 shows, in a horizontal view the folding-out means in folded position, with the wings 21 running between the pleats and with the fingers 30 outside thereof. This is the normal position when the flattened tube is pulled down towards the cargo unit.
[0018] In order to tear off a cover, it is desirable to maintain a grip at the lower edge of the following cover. Referring back to Figure 2 it is evident that the folding out means should have been provided with arms running outside of the pleats for engaging the same, as described in connection with Figure 5. In the upper position shown in firstmentioned figure the folding out means could then have retained the following cover, so it had been possible, by a simple pulling operation to sever the actual cover from the following.
[0019] The function of the opening means 19 will be evident from Figure 6. Full lines show arms 19 in the position when they engage inside the pleats 16, 17 and broken lines indicate the position of the arms when they have been swung outwards by the toothed segments 24. The contour of the mouth of the cover is indicated by a broken line at 35, and it is evident that the arms can be swung further apart, so the pleats 16, 17 will be practically straightened out.
[0020] The arms 19 are provided with claws, having a fixed jaw 36 and a pivotable jaw 37, which are operable by devices 38, built into the arms. Figure 7 shows jaw 37 in open position for introduction into a pleat. When this has been done the jaws 36, 37 are closed so the foil material is securely gripped. Thereafter the pair of arms 19 may be moved downwards along the guides 25, whereby first the tearing-off from the following cover occurs and the actual cover is mounted upon the cargo unit.
[0021] Figure 9 shows a portion of the flattened tube between two covers 12 and 13, but without any folding out and opening means. On this occasion the welding seams 14b, and 14c at the pleats are arranged obliquely in relation to the seam 14a interconnecting the layers of material at the central part of the tube. In this manner flaps 40 will be formed between the individual seams 14b and 14c and the tear-off line 15, which also with a branch runs out in each pleat. As mentioned above the quantity of air being entrapped within the cover, when the latter is pulled down over the cargo unit, causes a problem in that it tends to blow up the cover. To avoid this air evacuation openings 41 are provided, which advantageously are obtainable by the welding seams 14b and 14c not being brought fully out to the edges of the pleats. When the cover has been brought down over the cargo unit 20, as shown in Figure 10, the welding seams 14a, 14b, 14c will lie flat upon the top face of the cargo unit, with the upwardly open flaps 40 directed away from the cargo unit, before the heat treatment. Entrapped air will be forced out through openings 41, and may pass upwards through flaps 40, which during the following heat treatment will be crumpled to effectively close openings 41. Corresponding evacuation openings are obtainable with the embodiment according to Figure 2, where the welding seams 14b and 14c are aligned with the central seam 14a, and it is evident that workable evacuation openings may be obtained by a simple piercing of the foil material adjacent to a seam, which will be sufficient crumpled together during the heat treatment to close the openings.
[0022] Figure 11 shows a modification of the welding seams and tear-off lines as shown in Figure 9. The welding seams 14a, 14b and 14c are arranged in the same manner as shown therein, i.e. seams 14b and 14c run obliquely in relation to the central seam 14a, and do thus not run straight across the tube. The tear-off line 15 is however here arranged so it follows the welding seams. There are thus a central portion 15a between the pleats, as well as individual portions 15b and 15c along welding seams 14b and 14c in the pleats. This means that the mouth of a cover will show downwardly directed flaps 45, instead of the upwardly directed flaps 40, shown in Figures 9 and 10, which will make it more easy for opening means 19 to engage the cover and unfold the same.
[0023] The embodiments above described and shown in the drawings are examples only of the invention. Covers and operating devices may be varied in many ways within the scope of the appended claims, and with due consideration to the size of the cargo unit, as well as to the protection desired.
1. A method of manufacturing a protecting cover of shrinkable plastics foil having
a pleated portion (16, 17) along at least one of its sides, the cover being adapted
for use with a substantially prismatic cargo unit characterized in welding the foil
along a seam (14a) extending to the inward base of the pleated portion (or portions,
respectively), and thereafter welding the foil in each side of the pleated portion
by individual seams (14b, 14c), so no welding seam (14a, b, c) will interconnect more
than two layers of foil.
2. A method according to claim 1, where the cover is manufactured from a flattened
tube and is provided with two pleated portions characterized in arranging the individual
welding seams (14b, 14c) at the pleated portions obliquely in relation to the welding
seam (14a) running transversely in relation to the pleated portions and interconnecting
the foil at the central portion of the cover.
3. A method according to claim 2, where the covers, in a manner known per se, are
formed into a continous strip provided with tear-off lines characterized in arranging
the tear-off lines (15) to follow the welding seams (14a, b, c) also in the pleated portions (16, 17).
4. A method according to either of the preceeding claims characterized in stopping
the individual welding seams (14b, c) in the pleated portions (16, 17) short of the
outward edges thereof, to leave air evacuation openings (41) along the latter.
5. A device for applying a protecting cover (11, 12, 13) of shrinkable plastics foil
upon a substantially prismatic cargo unit (20) characterized in a magazine containing
a series of covers (11, 12, 13) formed into a strip and along at least one side being
provided with a pleated portion (16, 17), in which the individual covers are severable
along tear-off lines (15) and are welded so seams (14b, 14c) run individually along
the sides of the pleated portions (16, 17).and further including means (18) adapted
to be introduced into said pleated portion, or portions, and during feeding-out of
the strip to follow the pleated portion and, during a tearing-off operation, to grip
each side of a pleated portion at the sides directed away from each other.
6.Adeviceaccordingtoclaim5,characterized in further means (19) adapted to engage the
margin of the cover remote from the welding seams and to bring the engaged portions
outwardly, to straigthen-out the pleated portion.
7. A device according to either of claims 5 or 6, characterized in the first mentioned
means (18) causing the primary unfolding of the pleated portion comprises a wedge-shaped
member having two wings (21) foldable along a central ridge (22), as well as a finger
(30) running outside of each pleat and engageable with the wedge-shaped member.
8. A device according to either of claims 5-7, characterized in that the further means
(19) being provided to bring the cover margin remote from the welding seams outwardly
comprises hook-members (19) operating in pairs and connected to a common actuating
device (24).
9. A device according to claim 8, characterized in that each hook-member (19) is formed
as a clamping claw (36, 37) and is mounted in a guide (25) permitting a vertical displacement
along the cargo unit.