PACKAGING ELEMENT OR PREFORM OF FIBRE PULP WITH RAISED PORTIONS

Abstract: In a packaging element or preform consisting of a base material (1, 8) in sheet or web form (of which only small parts are shown) with a number of pocket-shaped raised portions (15) intended to be placed in a protective position between the packaged article (29) and external packaging means, e.g. a corrugated-paper box (30), the new feature consists in that the angle (21) between mutually opposing wall parts in the side wall (16) of the raised portions (15) is between 20 DEG and 40 DEG , preferably approximately 40 DEG . With this arrangement, an overloading of the raised portion (15) will cause the side wall (16) to be deformed plastically when acted upon by a roughly constant force while forming "accordeon pleats" (20), without the raised portion (15) at any time losing its supporting ability. The risk of the side wall (16) collapsing under load may be reduced further by giving the side wall (16) an outwardly convex curvature (not shown).

Description: PACKAGING ELEMENT OR PREFORM OF FIBRE PULP WITH RAISED PORTIONS TECHNICAL FIELD The present invention relates to a packaging element or preform of the kind set forth in the preamble of Claim 1. BACKGROUND ART Packaging elements of this kind are used as intermediary supporting means when packaging apparatus to be protected against impact in an outer packaging element. One example that may be mentioned is impact-sensitive electro¬ mechanical equipment, such as video-tape recorders, to be packaged in an outer corrugated-paper box for shipping purposes. When an article packed in this manner is exposed to rough treatment, e.g. by falling on a hard surface, the raised portions in the packaging element must be able to absorb at least part of the energy of the fall in order to protect the sensitive equipment. DISCLOSURE OF THE INVENTION In the situation referred to above, it is of great importance that the raised portions have an appropriate "compression characteristic", as they must be sufficiently rigid to resist deformation by loads within the permitted limits, but at the same time they must be able to yield under powerful impact loads, in order to prevent all the impact energy from being transmitted to the packaged equipment and damage the same. In order to achieve this effect, the packaging element or preform according to the present invention primarily exhibit also the features set forth in the characterizing clause of Claim 1. The effect of the feature set forth in item c in Claim 1 is that each raised portion or projection is given a certain limiting strength - corresponding to the greatest force it can withstand without being deformed - and by suitable choice of the size and number of the raised portions or projections, this makes it possible to adapt the packaging element or preform to whatever the packaged article concerned can withstand. The effect of the feature set forth in item d is that when the force referred to above is exceeded, the raised portions or projections will be compressed while providing a substantially constant counter-force without collapsing so that at all stages of the compression process they still have the same limiting strength. Because of the inherent properties of the fibre-pulp material, this process will result in a permanent deformation, so that it is possible when opening the package to ascertain that the packaged equipment has been exposed to inertial forces comparable to the deformation resistance of the raised portions or projections. Additional protection against the raised portions or projections collapsing may be achieved with the embodiment set forth in Claim 2. By means of the measures set forth in Claims 1 and 2 it is possible to achieve a controlled plastic deformation of the raised portions or projections, when these are subjected to loads exceeding a certain limiting value. It may, however, be advantageous to shape the raised portions or projections in such a manner, that they also enable an initial elastic deformation to take place, this amongst other things ensuring that the packaging element will lie under elastic compression between the packaged article and the outer packaging, in stead of lying loose and "rattle" between the two. Such an initial elastic deformation may be achieved with the embodiment of the invention set forth in Claim 3. BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present specification, the present invention will be explained in more detail with reference to the drawings, iji which Figure 1 shows an exemplary embodiment of a packaging preform according to the present invention as viewed against a major surface, Figure 2 is a sectional view along the line II-II in Figure 1, Figure 3 is a sectional view along the line III-III in Figure 1, Figure 4 shows one of the ends of the packaging preform shown in Figures 1-3 in a situation, in which the preform is folded-up so as to form a side protector for an electronic apparatus to be protected in a corrugated-paper box or the like, partly in section along the line IV-IV in Figure 5, Figure 5 is a partial sectional view along the line V-V in Figure 4, Figure 6 is a sectional view along the line VI-VI in Figure 4 and shows the packaging element in use when packaging a video-tape recorder, Figures 7-9 are three partial sectional views roughly corresponding to the central part of Figure 3 through one of the pockets of the packaging element, and shows partly a modified shape of the pocket, partly how the pocket is compressed under a high load, and Figure 10 is a sectional view along the line X-X in Figure 7. DESCRIPTION OF THE PREFERRED EMBODIMENTS The exemplary embodiment of a packaging preform according to the present invention shown in Figures 1-4, which - like the remainder of the exemplary embodiments referred to in the present specification - is contemplated as being manufactured in a similar manner as the well-known packaging means for eggs, e.g. egg trays and egg cartons of fibre pulp material, i.e. by aspirating a layer of fibre pulp on a suction mould, comprises a generally plane body portion 1, on which is shaped a number of raised portions or projections 2-4, partly of various shapes, which in relation to the body portion 1 can be described as raised portions or recesses, depending on whether the preform is viewed from the same side as shown in Figure 1 or from the opposite side. Because of the method of manufacturing, the wall thickness in the body portion 1 and the projections 2-5 are of the same order of magnitude, in practice normally between 1 and 3 mm. For convenience, all these projections will be described as "pockets" in the following specification, and it will be evident from the context, whether they are to be regarded as raised portions or recesses. Thus, the pockets 2-5 are constituted by - a number of central pockets 2 placed in a row on the centre line of the body portion 1, - two sets of side pockets 3, placed along a respective one of two side portions 6 and 7, contiguous with the body portion 1 and in alignment with the latter in the situation shown in Figures 1-3, - two major end pockets 4, shaped on end portions 8 contiguous with the side portion 6 and in the situation shown in Figures 1-3 in alignment with the latter- and two minor end pockets 5, shaped on end portions 9 contiguous with the side portion 7 and in the situation shown in Figures 1-3 in alignment with the latter. The exemplary embodiment of a packaging preform shown in Figures 1-3 is primarily intended for use as a side protector for a video machine for home use, in the present case having the shape of a closed flat box. When the packaging preform shown is placed as a side protector on such an apparatus, the body portion 1 extends in contact with and, along one of the long sides of the apparatus, the side portions 6 and 7 being bent so as to come into contact with the opposite and the lower side repectively, while the end portions 8 and 9 have been bent relative to the side portions 6 and 7 respectively into contact with the two end surfaces of the apparatus. In order to make it possible to adapt the packaging preform to apparatus of varying heights, the preform is provided with two sets of folding lines, viz. a set of minimum folding lines 10 and 11 and a set of maximum folding lines 12 and 13, intended for bending or folding the preform to make it conform to an apparatus of relatively lesser and relatively greater height dimensions respectively. As shown in Figure 4 the side portions 6 and 7 have been bent through 90° relative to the body portion 1 about the maximum folding lines 12, while the end portions 8 and 9 have been bent, likewise through 90°, about the minimum folding lines 11 relative to the side portions 6 and 7 respectively; as will be evident from Figure 4, it will be necessary to bend the end portion 9 first, since the major end pocket 4 shaped on the end portion 8 is to fit on the outside of the lesser end pocket 5 on the end portion 9. As will be evident from Figures 3 and 5, those walls in the end pockets 4 and 5, which in the situation shown in Figure 4 are in mutual frictional engagement, form an angle 14 with each other. With material of the kind referred to here, it has proved expedient to choose an angle 14 of approximately 30°. For ease of production is has proved expedient to form all the side surfaces on all the pockets 2-5 with this mutual angle of approximately 30 β with the ' relevant base surfaces. The angle 14 is chosen in consideration of two mutually contradicting desires, viz. firstly, that in the situation shown in Figure 4, the minor end pocket 5 should engage so firmly with the major end pocket 4, that these parts do not come loose of each other, partly due to the residual elasticity in the folding line, partly due to loads caused by ordinary handling of the packaging element, including placing it as a side protector on the apparatus to be packaged, and - secondly, that it must be possible to stack un-bent packaging preforms of the shape shown in Figures 1-3 on top of each other, without this stacking causing them to engage each other so firmly, that it is impossible to remove single preforms from the stack. When using the material referred to above it has been shown that this angle should be at least 20° and at the most 40° for these conditions to be met. It is worthy of note that the two inter-engaging pockets 4 and 5 shown in Figure 4 have a total strength corresponding to two pockets. In this manner, extra protection is achieved in a region, which may be particularly strongly exposed. Figure 6 shows how a video-tape recorder 29, of which no more than a part of the long side is schematically indicated, is supported against the inside of a corrugated-paper box 30 by means of the central pockets 2 and the side pockets 3. To make it easier to move the packaging element and the video-tape recorder together to the mutual position shown in Figure 4, the free edges of the side portions 6 and 7 are provided with guiding-in lips 31. The latter may be formed during the moulding operation proper or during the subsequent pressing, which may comprise imprinting of the folding line, cutting-off of flash etc. The pocket 15 shown in Figures 7-10 is shaped roughly in the same manner as the pockets 2 and 4 in the exemplary embodiment shown in Figures 1-6, but differs from the latter partly by having all side walls curved with the convexity facing outwards, and partly by being shaped with a view to making it able to yield, in part elastically, in part plastically. Thus, the pocket 15 comprises a side wall 16, which as evident from Figure 10 is curved all the way round with varying curvature so as to form the side wall in a "rounded rectangular pyramid", said side wall 16 extending from the base material, in this case constituted by the body portion 1 or the end portion 8 as shown in Figure 1, to a bottom wall 17 consisting of a peripheral rim portion 18 surrounding a support nipple 19 placed centrally on the bottom wall 17. When being loaded within a limited interval of loading force, the rim portion 18 will, as indicated in Figure 8, function as a kind of disc spring, which can be utilized e.g. to insert the packaging element "rattle-free" between the article being packaged, e.g. the video-tape recorder 29 shown in Figure 6, and the outer packaging, e.g. the corrugated-paper box 30 likewise shown in Figure 6. If the load on the packet 15 is increased beyond the limited force interval referred to, and the rim portion 18 yields to such an extent, that the side wall 16 comes directly under load, a progressive plastic deformation of the side wall 16 will occur, forming "accordeon pleats" 20 as indicated in Figure 9. By suitable choice of the angle 21 between the two mutually opposing parts of the side wail 16 it is possible to create optimal pre-conditions for the creation of such accordeon pleats, the progressive forming of which has proved to allow continued pressing-down of the side wall 16 to occur without any noticeable increase of the pressing force, also without the side wall at any stage collapsing and losing its supporting ability. In addition to the choice of the angle 21 within an optimal interval, the curved shape of the side wall 16 shown in Figure 10 contributes towards avoiding that the side wall 16 collapses in the manner mentioned above. Even though the generally plane side walls in the various pockets 2-5 shown in Figures 1-6 in the majority of cases will have a minimal tendency to collapse under load of the kind referred to above, the curved shape of the side wall shown in Figure 10 provides extra protection against such collapsing. Experience up to the present has shown that, when using conventional pulp material made from waste paper, the angle 21 should lie in the interval between 20" and 40", an angle of approximately 30° appearing to be optimal with a view to ensuring that the plastic deformation of the side wall 16 occurs in the manner indicated in Figure 9 without risk of collapsing. It will be seen that this preferred angle interval and this preferred angle corresponds to that angle interval and that angle respectively as explained above, which constitute the best compromise between on the one hand the mutual locking ability for the end pockets 4 and 5 and on the other hand the possibility of removing packaging preforms singly from a stack. It is, however, probable that such coincidence will not occur in packaging preforms differing only slightly from the example shown. The fibre pulp referred to may be made from e.g. vegetable fibre mass, especially wood pulp, or paper p p, including recycled such. LIST OF PARTS

Claims: CLAIMS 1. Packaging element or preform of the kind manufactured from fibre pulp and comprising a) a base material (1,5,6,7) in web or sheet form, and b) protruding from said base material, projections (2- 5,15) with a wall thickness of the same order of magnitude as the wall thickness of the base material, characterized in c) that each of the projections (2-5,15) comprises an encircling side wall (16) shaped in continuation of the base material and converging away from the latter, as well as an end wall (17) shaped in continuation of the opposite edge of said side wall, of which end wall (17) at least the rim portion (18) situated closest to the side wall extends at least approximately parallel to the base material, and d) that the oppositely facing sides in the side wall (16) form an angle (21) with each other of at least 20" and at the most 40°, preferably approximately 30°. 2. Packaging element or preform according to Claim 1, characterized in that at least substantial portions of the side wall as seen in a sectional view (X-X) parallel to the base material are curved with outwardly facing convexity. 3. Packaging element or preform according to Claim 1 or 2, characterized in that in at least one raised portion (15), the end wall (17) is shaped with at least one projection (19) facing away from the base material.

Inventors: RASMUSSEN TORBEN, RASMUSSEN, TORBEN
Applicants: HARTMANN AS BRDR, BROEDRENE HARTMANN A/S
Application year: 1993
Main classification: B65D81
IPC codes: B65D81