MULTILAYER PAPER PACKING PROVIDED WITH CLOSED MEMBRANE SURFACE FULL OF GAS UNDER PRESSURE

DESCRIPTION

The present invention relates to a new packing comprising a multilayer paper bag coupled with an airbag device to be positioned inside the same bag.

The multilayer paper bags are used for various aims such for example the stocking and transport of pieces of various kind. As a way of example, referring to the automotive field, said multilayer paper bags can be used for stocking and transport of spare pieces of a common motor vehicle in order to maintain their integrity and finishing.

For ease of explanation, in the following detailed description of the invention (as well as in the appended drawings) it will be referred, in not limiting way, to the practical case of packing for motor vehicle bumpers.

In the technical field referred there are known boxes in undulated board, by means of which there is guaranteed the maximum packing stiffness with the drawback that the optimization of the stocking space is not allowed in case of packing or stacking the packed product.

In the bumpers specific case, the continuing research on materials and the increasing attention paid by the automotive industry both to active and passive safety, have lead to even more flexible and deformable bumpers. Therefore the need to provide the stiffest packing possible, which can avoid that the bumper is deformed during stocking, can favor the use of a packing in undulated board. On the one hand, said packing in undulated board guarantees surely very high performance in terms of packing stiffness, on the other hand it presents however a series of drawbacks.

The main disadvantage of the undulated board boxes, as yet said, is that it is not allowed the stocking space to be optimized, for example, in case of packing (of bumpers) or more generally in case of stacking. The other disadvantage is linked to economic factors since the multilayer paper bag provided with airbag, object of the present invention implies logistic costs, clearly lower than those for the yet known undulated board boxes.

Therefore, aim of the present invention is to provide a new multilayer paper bag with stiffness performance similar to the one guaranteed by the undulated board packing, by introducing a closed membrane surface full of gas under pressure (in the following defined simply as airbag) and provided with inflation valve between the product to be packed and the same paper bag. In order to reach the prefixed aims, the inventive object is substantially provided with two elements:

• a multilayer paper bag having final dimension proportional to the dimensions of the product to be packed;

• a closed membrane surface full of gas under pressure having lower dimensions than those of the paper bag. These and other advantages will be clearer from the detailed description of the invention which refers to the following drawings 1/7 to 7/7 in which it is shown an absolutely not limiting preferred embodiment of the invention (case of bumper packing). In particular:

• figure 1 shows an axonometric view of the multilayer paper bag;

• figure 2 shows an axonometric view of the airbag without air therein and with air therein;

• figures 3 to 5 are axonometric views of the multilayer paper bag as a whole provided with airbag interposed between bag and product to be packed in the packing various steps;

• fig. 6 is an axonometric view of the multilayer paper bag provided with airbag, once the packing is closed with the inner portions highlighted and in particular with the airbag not in pressure;

• fig. 7 shows an axonometric view of the multilayer paper bag provided with closed airbag with the inner portions highlighted and in particular with the airbag in pressure;

• fig. 8 is a tridimensional model of the bumper for motor vehicle integral with a closed membrane surface full of gas under pressure along the whole surface of the product to be packed;

• fig. 9 is a tridimensional model of the bumper for motor vehicle partially integral with a closed membrane surface full of gas in pressure along a section of the product to be packed.

Referring to said appended figures, it will be described in detail a preferred embodiment of the present invention referring for ease and in an absolutely not limiting way to the case of packing a bumper for motor vehicle.

A first preferred embodiment of the packing is described in figures 3 to 5. In said figures, the motor vehicle bumper 2 is introduced inside the multilayer paper bag 1 ; after introducing the bumper 2 inside the bag 1, it is introduced the airbag 3 provided by the manufacturer together with the paper bag 1 ; in the following the multilayer paper bag 1 is closed again paying attention that the inflation valve 4 of the airbag 3 remains outside the packing; then the gas is introduced inside the airbag 3 until the packing reaches the desired or predetermined stiffness level; finally, the inflation valve 4 is closed again. The airbag is usually made up of a polymeric material membrane, which can be realized in different shapes according to the packing kind to be realized.

A second preferred embodiment of the packing is the one represented in fig. 8, wherein it is provided that the membrane surface 3 (or airbag) is applied on the bumper 2 so that the whole surface of the bumper 2 (in this case the inner concave surface) is covered.

A third preferred embodiment of the packing is the one represented in fig. 9, wherein it is provided that the airbag 3 is applied directly on the bumper 2 so that the sole central area of the same bumper is covered.

In said figures 8 and 9, the multilayer paper bag 1 is not represented, which is anyway applied in combination with the bumper 2 integral with the airbag 3.

The thus packed product (bumper for motor vehicle) reaches the stiffness levels comparable to those obtainable with undulated board boxes. In fact, there have been carried out structural analyses by means of the finite element technique (FEM models) on the paper bag packing - airbag assembly, which have lead to the finding that by attaching a membrane in pressure to a bumper, it is increased the bumper stiffness thus making it less deformable when subjected to loads.

The production process of the paper bag provided with airbag object of the present invention comprises substantially three different steps:

i. realization of the paper wrapping 1 ;

ii. realization of the airbag 3 and application of the inflation valve 4;

iii. assembly of the paper wrapping 1 and of the airbag 3.

Concerning the first step relative to the realization of the paper wrapping, the principal physic features of the paper wrapping are shown in the following table 1 : Caratteristica Codifica Definizione

Height Hi Proportional to the object to be

packed

Length L Proportional to the object to be

packed

Flap F Proportional to the object to be

packed

Composition Comp Proportional to the object to be

packed

Table 1 - specifications for the realization of the paper wrapping

The method usually used for the realization of the paper wrapping starting from the starting specifications provided, described in the previous table 1 , comprises the following steps:

■ to cut the paper sheets needed to realize the wrapping, considering that:

a. the length of the sheets (L _f ) will be L _f = Lj + 4 cm; b. the height of the sheets of the inner layers (Hsj _nt ) will be Hsj _nt = 2 x ¾

c. the width of the sheet forming the outer layer (Hsex _t ) will be Hsext = Hsj _nt + 8 cm;

■ to unfold on a sufficiently great working plane the outer paper sheet;

■ to overlap on the outer sheet the other sheets in the needed order to obtain the kind of desired wrapping, paying attention that all the sheets are aligned longitudinally according to the central axis of the outer sheet. The alignment has to be made such that the lower sheet goes over the overlapped sheets by about 4 cm;

^■ to apply on the two over going stripes some hot glue along the whole length of the bag;

■ to fold again the four over going centimeters so that the outer sheet adheres to the inner one thus creating a sandwich with the intermediate layers;

■ to repeat the operation on the other long side;

■ to provide an incision on the wrapping to allow the valve 4 to go out once the packing is ended;

■ after drying the glue, to fold one time the obtained wrapping along its whole length (the fold can be symmetrical or asymmetrical according to the desired geometry of the bag, when the mono-fold is asymmetrical, this has to be such that the right dimension of the flap requested by the client is guaranteed);

^■ to close the two short ends of the bag folding the bag on itself for two centimeters;

^■ to block the fold by means of clamps;

^■ to apply a coated paper band across the fold and the bag;

■ to heat the bands so that the polyethylene spreading blocks the fold on the bag.

In parallel to the realization of the paper wrapping, it is possible to proceed to the realization of the inner airbag 3. The dimensions of the inner airbag depends on the dimensions and geometry of the object to be stiffened by means of the packing and are determined starting from the following specifications shown in table 2: Dimensione Codifica Calcolo

Airbag length L Equal to the length of the object to be stiffened or of the portion of the same mostly subjected to stress

Airbag height H Equal to the length of the object to be stiffened or of the portion of the same mostly subjected to stress

Airbag depth Z It is determined by wrapping the object to be packed with a paper wrapping and measuring the maximum distance between the inner surface of the object and the paper wrapping it.

Table 2 - specifications for the realization of the airbag

Once the dimensions of the inner airbag L, H, and Z are defined, its realization comprises the following steps:

^■ to determine the number of air chambers to be realized (Nc) Nc= H Z;

^■ to take a film tubular with plate (P) equal to P=2 x Z x Nc;

^■ to cut a sheet of length (LF) LF = L + 4cm;

^■ to mark the tubular segment dividing it in Nc equal parts, each one of width 2Z;

^■ to position two separators in Teflon 1cm for 1cm inside the tubular, respectively at a one third and two third of the marks just realized;

^■ to carry out thermo-welding at the marks so that the tubular segment is divided in Nc air chambers;

^■ to extract the separators previously introduced. By extracting the separators, it is obtained that the realized air chambers will be in communication the one with the other and the only valve will be sufficient to inflate them all together; ■ to mark with a pen the half of each obtained channel on the upper and lower portion of the tubular;

■ for each channel, to weld the upper central dotted line with the upper central dotted line of the channel at its right and the lower dotted line with the lower dotted line of the channel at its left;

■ on the central channel to apply the inflation valve 4;

■ to seal the short sides of the airbag by means of two thermo-welds.

Once the paper wrapping 1 and the airbag 3 are realized, it is possible to assembly the two elements according to a method comprising the following steps:

■ to position the paper bag 1 on a sufficiently great working plane with the side, which can be opened, faced to the operator and the hole for the inflation valve (4) faced upwards;

^■ to take the airbag 3 to be introduced therein;

^■ to open the paper bag 1 ;

^■ to position the airbag 3 inside the paper bag 1 ;

^■ to introduce the inflation valve 4 inside the hole provided on the wrapping;

^■ to fold the paper bag 1 and to proceed to the assembly.