A SHOCK-ABSORBING WRAPPING AND A METHOD FOR MANUFACTURING SUCH WRAPPING

Abstract: A customized shock-absorbing wrapper band comprising at least two rows of gas-filled cushions (14) of arbitrary shape and size formed by joining two flexible webs (16,17), at least one of which (16) is thermoformable, and pressurizing the thermoformed recesses (21) when sealing such by the other web (17) in a sealing station (22) of a thermoforming, roller operated machine.

Description: The present invention relates to a shock-absorbing wrapper according to the preamble of claim 1 and to its method of manufacture. Refrigerators and freezers, washing machines and similar prismatic articles are frequently damaged during transport from the manufacturer to the user. Even if the goods are well wrapped, shocks or collisions against other objects may tear or deform the wrapping. One object of the present invention is to provide a shock-absorbing wrapper which may be applied along edge-portions of the article. This gives a protection not only to the edge as such but also the side surface between two edge wrapper strings will be maintained at a certain distance from other objects. One additional object of the invention is to provide a technique which offers an optimum of transport and storage protection for products wrapped in a wrapping having preformed cavities of individually variable size and shape. Another object of the invention is to provide an efficient wrapper manufacturing method. From the packaging technique within the electronics industry there are known webs having formed therein small (in the size of 10 to 20 mm) spheres filled by air and spaced in a close sphere-to-sphere pattern. Such wrappers provide shock-absorption in combination with an outer protective package, generally a cardboard box. Sheets of said wrappers are simply placed along the planar innersides of the box. A shock-absorbing wrapper comprising two flexible webs joined together to form at least two longitudinally extending rows of gas-filled cushions of arbitrary shape and size with an intermediate longitudinally extending area therebetween is disclosed in FR-A-2257501. However, should one of the cushions be punctured, it will deflate and any shock-absorbing properties will of course be lost. This document also discloses a technique which makes use of elongated, blown up, air filled, proximate cylindric spaces between a pair of flexible webs. Such a technique also provides a restricted pattern configuration for the protective elements of the wrapping. The configuration may be described as a "no-distance" cylinder to cylinder configuration. In other words the cylinders are so close to each other that the web loses its folding characteristics. A single web of shock-absorbing wrapper is disclosed in US-A-3575781. The web has protruberences thermoformed therein which are provided with a plurality of uniform size facets having ridges therebetween which serve to disperse any impact force. Due to the inherent rigidity of the single web, additional protruberences have to be formed between the main protruberences in order to enhance the flexibility of the web. The present invention overcomes the disadvantages inherent in the prior art by providing a wrapper according to claim 1 and a method of manufacture according to claim 2. In order to safeguard the protective function of the cushions, a gas, preferably air, is blown in between the webs just before the welds of each individual, thermoformed recess are finished. One article, for instance a freezer, is transferred from a wrapping station on a wooden pallet and is protected by a cardboard wrapper and/or wooden frames. A shock-absorbing wrapper according to the present invention is applied at least along the vertical edge-portions. Thereafter a shrink film is applied around the object, and after being heated the shrink film fixes the freezer, pallet and any wooden frames plus the shock-absorbing edge wrappers. The invention will now be described in greater detail by way of example only, with reference to the drawings in which Fig. 1 schematically shows a freezer being wrapped by edge-protection means according to the present invention, Fig. 2 shows a portion of a wrapper band according to the present invention, Fig. 3 shows a section through the band, but with the longitudinal portions of the band folded 90° relative each other, Fig. 4 very schematically shows the method of manufacturing the wrapping band, Fig. 5 is a cross-section taken from Fig. 4, Fig. 6 is a plan view showing the side of the band having specific cushions according to a second embodiment, Fig. 7 is a section along line VII-VII in Fig. 6, and Fig. 8 is a broken section along line VIII-VIII. In Fig. 1, the reference numeral 10 denotes an arbitrary, prismatic article, for instance a freezer, which is to be wrapped and transported, standing on a pallet 11. In the traditional manner the freezer may be wrapped by corrugated cardboard. In order to protect the freezer efficiently during the transport, bands of pressurized, thermoformed cushions are attached along the vertical edge-portions of the freezer. Possibly, similar bands may be attached along the upper horizontal edge-portions. As appears best from fig. 2, each band 12 comprises two rows 13 of cushions 14 having four-sided planar shape. The rows of cushions are separated by a solid strip 15 which is wide enough for allowing folding of the band such that the rows of cushions will be placed 90° relative each other, as shown in fig. 3. The bands 12 may be glued to the corrugated cardboard wrapper. In that case where this wrapper is enforced by wooden frames, the band may be stitched to such applications which is best carried out by a robot. Finally, the entire unit is enclosed within shrinkable plastics which after heating tightens the seperate elements to a unit and forms a reinforced transport protection. The manufacture of the band is carried out as schematically shown in fig. 4, where basically thermoforming machinery is shown operating from a pair of rollers carrying webs of thermoformable material. Two webs 16, 17 of plastic foil, preferably a LD-polyethylene, are unrolled from rollers 18, 19 and transported generally in a horizontal direction past stations for thermoforming recesses forming bladders after being sealed by the other web. The recesses have a formstable shape also when the bladders are unpressurized. In one embodiment the bladders are given a four-sided planar shape and arranged such that they cover a substantial portion of the surface of the band, only surrounded by the necessary weld seams. In order to give the cushions a sufficient depth and predetermined lateral dimensions for the intended shock-absorption function, the bladders are permanently thermoformed with a minimum of mechanical memory from at least one of the webs. At 20 there is shown a station for forming recesses 21 by thermoforming, i.e. a certain portion of the material of the strip is heated and sucked and/or pressed into a mold. The two bands 16, 17 are thereafter brought to pass a sealing station 22 for longitudinal welding of the webs 16, 17. In a manner known per se the station 22 may comprise the traditional heat sealing equipment or heated wheels 23 for welding webs along the outer longitudinal edges, as well as between the recesses or bladders 21 so that there is obtained an elongated strip for folding of the webs. Gas, preferably air, is blown in between the bands 16, 17 from a source for pressurized air 24 immediately before the welding station 22, such that the recesses covered by the other web are safely pressurized by gas before they are sealed to cushions 14 which takes place in the welding station 25 where heated jaws operate in the cross-wise direction between the bladders 21. The band manufactured in the described manner may be rolled up or folded in a storage, from which it may be taken out as desired, but of course the machinery may operate also intermittently and produce bands as desired and feed such out from the machinery in desired predetermined lengths. The two rows of gas-filled, pressurized cushions in the embodiment according to figs. 1-5 having a square/rectangular basic shape offer excellent protection for edge-portions as well as surfaces therebetween. Possibly, both webs may be provided with bladders, and the attachement to the object to be transported may be carried out in different manners. The lower web 17 having no bladders may for instance be provided with a layer of glue covered by a removable protective film. In fig. 8 there is shown a tool to be used in a conventional thermoforming machine for forming "bladders" or recesses of basically two different types (or alternatively fig. 8 may be said to represent a cut piece of a sealed two web wrapper having been thermoformed in said tool). The section in fig. 7 shows two different types for the bladders 26, 27 and a certain region 28 therebetween where the two webs are sealed. The reference numeral 28 represents folding denotations for facilitating the folding of the piece of band, generally to any required angle between 0-90° around a horizontal axis. Fig. 8 shows the height 30 and length 31 of the cushions in the vertical direction in said fig. The possibility of providing permanently formed, possibly gas-filled and pressurized, cushions or bladders improves drastically the protecting ability of the wrapping. Even if one or several bladders are punctured, such bladders maintain a shock-absorbing capacity also after being depressurized because the punctured bladder acts as a shock-absorber from which gas has to be pumped out through the punctured areas. Basically, the thermoforming procedure does also allow a 100%-tailored piece of cushion band for a specific shock-absorbing purpose, meaning that the wrapping will act at an optimum irrespective of the shape of the article on which it is fastened.

Claims: 1. A shock-absorbing wrapper comprising two flexible webs (16, 17) joined together to form at least two longitudinally extending rows (13) of gas-filled cushions (14) of arbitrary shape and size with an intermediate longitudinally extending area (15) therebetween which has a transverse dimension sufficiently large to permit said shock-absorbing wrapper to be folded therealong, characterized in that one (16) of said webs is thermoformed and has permanently formed, form-stable recesses (21) therein which, together with the other flexible web (17), define the said cushions (14). 2. A method of manufacturing a shock-absorbing wrapper according to claim 1, said method comprising providing a first longitudinally extending flexible web (16), providing a second longitudinally extending flexible web (17), permanently thermoforming said first longitudinally extending flexible web (16) to provide first and second longitudinally extending rows of form-stable recesses, pressurizing said first and second longitudinally extending rows (13) of thermoformed recesses (21) by injecting a gas into said recesses (21), and adhering said first and second longitudinally extending webs together at least about the perimeter of each of said first and second longitudinally extending rows of thermoformed recesses (21) and at said intermediate longitudinally extending area (15), said intermediate longitudinally extending area (15) having a transverse dimension sufficiently large to permit said shock-absorbing wrapper to be folded therealong. 3. A method as in claim 2, characterized in that the gas, preferably air, is blown in between the webs (16, 17) just before completing the welds of individual recesses. 4. The use of a shock-absorbing wrapper according to claim 1, wherein the wrapper band is applied to at least one vertical edge portion of prismatic transported goods (10).

Inventors: HELLGREN, BO, OLSSON, ROINE
Applicants: AB AKERLUND & RAUSING, ELECTROLUX MAJOR AND FLOOR CARE APPLIANCES AKTIEBOLAG
Application year: 1989
Main classification: B65D81
IPC codes: B65D81, B32B3, B29C65