HIGH-STRENGTH TUBULAR BEAM OF FOLDED CORRUGATED CARDBOARD

Abstract: A high-strength tubular beam of folded corrugated card­ board, for example for constructing disposable load-carrying platforms, comprising a single corrugated cardboard sheet (1) folded back several times on itself to form an overall section of right angled or isosceles trapezium form (4, 6′, 8′, 8, 6), divided into two adjacent rectangular or rectangular trapezium half sections (4, 6′, 8′, 18′), (4, 6, 8, 18), each comprising two mutually inverted triangular channel configurations (16′, 14′, 12′) - (8′, 10′, 12′), (10, 8, 12) - (16, 14, 12), which mate with each other and have a common diagonal (12, 12′).

Description: HIGH-STRENGTH TUBULAR BEAM OF FOLDED CORRUGATED CARDBOARD This invention relates to a box beam of folded corrugated cardboard, which has high resistance to bending and to transverse crushing, and is suitable for example for constructing load resting or carrying platforms of the pallet type. Disposable corrugated cardboard pallets are known, formed from a set of cardboard box-section beams disposed mutually crossing. Said box beam elements, of known types are formed from two sheets of cardboard which are folded several times back on themselves to form, respectively, the actual body of the box element and a cover therefor which is fixed to this latter by gluing, and which ensures the transverse constituency of said body and improves its bending resistance. This body is in the form of a beam of parallelepiped form, constituted by two adjacent symmetrical elements, the crosssection of each of these comprising a diagonal which is.locked against central abutments which rise from the base of said parallel epiped form. Said central abutments are produced by punching them from the sheet which constitutes the parallelepiped beam, and are disposed alternately on one and the other side of the axis of lon=itudinal symmetry of said sheet, to which they are joined along said axis of longitudinal symmetry. The use of such box beams, for example for forming load-carrying platforms in general, has shown up drawbacks driin from the fact that it is necessary to prepare two separate corrugated card- board sheets provided with respective predetermined creasing lines, and of which one, i.e. that de-i-ed to form the boiy cf the box element, must also be subjected to a punching operation or creating said central abutments. after this, the second sheet, which has been previously folded several times back on itself, must be assembled. The present patent provides and protects a tubular corrugated cardboard element which forms a beam suitable, for exsmple, for constructing disposable load-carrying platforms, and is composed of a single sheet of cardboard folded back on itself several times, to provide, by way of a simple and rational constructional design, properties in the form of resistance to bending, to transverse crushing and to deformation of its cross-section which are comparatively superior to those obtainable with the aforesaid norim box beams. Moreover, because of the absence of punching operations, and by virtue of being composed of a single sheet, it can be manufactured automatically and continuously by machine, without manual intervention. According to the invention, the proposed tubular element is composed of a single corrugated cardboard sheet which is symmetrically folded back several times on itself to form a beam of right angled or isosceles trapezium form, this section being divided into two adjacent symmetrical half sections, each comprising two channel configurations which are connected together by a coon diagonal. Suitable adhesive zones are provided in order to ensure the consistency of said comrlex section. The characteristics and constructional merits of the invention will be more apparent from the detailed description given hereinafter, with reference to the figures of the accompanying drawings which illustrate one particular embodiment thereof by way of nonlimiting exar.le. Figure 1 is a cross-section through a tubular element constructed in accordance with the invention. Figure 2 shows a completely extended sheet of cardboard arranged to form the tubular eleent of Figure 1. Figure 3 is a perspective view of a pallet or load-carrying platform constructed ath a tubular element according to the invention. Said figures show a corrugated cardboard sheet 1 of constant width and indefinite length, the axes of its corrugations being orthogonal to the lon itudinal axis of synmetry 2 of said sheet. Said flat sheet 1 is provided longitudinally with a series of predetermined dreasing lines, which are symmetrically disposed about the longitudinal axis of symmetry 2. More specifically, as shown in Figure 2, the sheet 1 comprises two predetermined creasing lines 3 and 3', which define a central longitudinal portion 4 straddling the lonoitudinal axis of symmetry 2 and having a length equal to that of the tubular element 101 which is to be obtained, this latter being shown in section in Figure 1. Said pair of lines 3 and 3' is arranged to enable the two sheet side portions lying to the side of said central portion 4 to be folded upwards. Externally to the lines 5 and 3', there are two further predetermined creasing lines 5 and 5', which with respect to tir folding direction are concordant with the preceding. Between the pairs of lines 3 and 5, and 3' and 5', there thus become defined two respective longitudinal strips 6 and 6', having a width equal to the height of the cross-section of the tubular element to be obtained (Figure 1). Two predetermined creasing lines 7 and 7' are provided in symmet- rical positions externally to the lines 5 and 5', to define, with the aid of said lines 5 and 5', two further strips 8 and 8 respectively. The lines 7 and 7' are concordant with the lines 5 and 5', and the strips 8 and 8' have a width which is practically equal to one half the width of the cross-section of the tubular element, less the thickness of the cardboard sheet. Again in a symmetrical position externally to the lines 7 and 7', there are two further lines 9 and 9' concordant with the preceding, and defining two longitudinal strips 10 and 10 having a width practically equal to the thickness of the beam, less double the thickness of the cardboard sheet as shown in Figure 1. Symmetrically in positions external to the lines 9 and 9' there are a further two lines 11 and fit, which are discordant with the preceding and define two longitudinal strips 12 and 12 respectively. These latter have a width which is practically equal to the length of the hypotenuse of the right angled triangle defined by the catheti 8 and 10, or 8' and 10', as shown in zaire 1. Beyond the lines 11 and 11', and again in a symmetrical position, there are lines 13 and 13 which are concordant with the lines 11 and 11', and define tXlo further longitudinal strips 14 and 14'. These latter have a width practically equal to that of the corresponding strips 10 and 10'. Finally, in a symametrical position externally to the lines 13 and 13', there are to marginal lonrntudinal lines 15 and 15' concordant with the latter lines, and defining two strips 16 and 16' having a width practically equal to that of the strips 8 and 8 respectively. To the side of the lines 15 and 15' there are the longitudinal edges 17 and 17' of the flat sheet 1, which define two outer strips 18 and 18' having a width practically equal to that of the strips 10 and 10', or 14 and 14'. Starting with the flat sheet 1, the tubular element or beam 101 which is shown in Figure 1 is obtained by successively folding said sheet following the folding directions of the aforesaid lines, until the strips 16 and 16' mate with the central portion or base 4, the strips 14 and 14' mate with the strips 6 and 6' respectively, and the strips 10 and 10' mate with the strips 18 and 18, these latter resting one against the other. Simultaneously with said folding operation, the sheet is provided with suitable adhesive zones intended to ensure the transverse consistency of the beam 101. In this manner, a tubular element is obtained having elevated properties of resistance to bending, to transverse crushing and to deformation of its cross-section, and of which the configuration and component elements are clearly visible in Figure 1. From said figure it can be seen that the cross-section of the beam has an overall rectangular configuration which is divided into two adjacent symmetrical half sections which mate along the vertical longitudinal plane of symmetry through said beam. Furthermore, each half section comprises two triangular configur- ations which in the case of the left hand half section are defined by the strips 8, 10 and 12, and by the strips 16, 14 and 12 respeatively. The two triangular configurations are connected together by a common diagonal constituted by the strip 12, and are mutually inverted. Finally, it is apparent that by suitably sizing the width of the component strips it is possible to obtain a beam 101 having an overall section different from that shown, for example square or of isosceles trapezium form, this latter constituted by two adjacent half sections of rectangular trapezium configuration. Using the tubular element portions according to the invention, disposable pallets or load-carrying platforms, or platforms for storing goods can for example be constructed, together with other structures for uses other than the preceding. One of said pallets is shown in perspective view in the accomBany- ing Figure 3. The invention is not limited to the single embodiment heretofore described, and modifications and improvements can be made thereto without leaving the scope of the invention, the fundamental characteristics of which are summarised in the following claims.

Claims: PAT@@T CLATMS 1. A tubular beam of folded corrugated cardboard as heretofore described, characterised by being constituted by a single corrugated cardboard sheet (1) having its corrugations orthogonal to its longitudinal axis (2), said sheet (1) bein folded back several times on itself parallel to its axis (2) to for an overall section of right angled or isosceles trapezium form (4, Ó', 8', 8, 6), and divided into two adjacent half sections (4, 6', 8', 18') (4 6, 8, 18), which mate along the longitudinal symmetrical axis of the beam (101), and which each comprise two triangular channel configurations (16' 14' 12t) - (8', 10', 12'), (10, 8, 12) (16, 14, 12) which mate along a common diagonal (12'), (12), and are mutually inverted. 2. A tubular beam as claimed in claim 1, characterised in that said single cardboard sheet (1) arranged to constitute said overall section of right angled or isosceles trapezium form (4, 6', 8', 8, 6) is of constant width and indefinite length, and comprises, on both sides of a longitudinal central portion (4), seven predetermined creasin lines (3, 5, 7, , 11, 13, 15) - (3', 5', 7', 9', 11', 13', 15'), of which the first four (3, 5, 7, 9) - (3', 5', 7t, 9') are concordant with respect to their folding direction, the other three (11, 13, 15) - (11', 13', 15') being discordant with the preceding (3,5,7,9) - (3', 5, 7', 9'); said lines defining, starting from said central portion (4), a first (6, 6'), a third (10, 10'), a fifth (14, 14') and a seventh (18, 18') strip of width substantially equal to the heiSht of the beam (101), a fourth strip (12, 12') of width substantially equal to the common diagonal of the triangular channel configurations, and a second (8, 8') and a sixth strip (16, 16') of width substantially equal to one half the width of the beam. 3. A tubular beam as claimed in claim 1, characterised in that the first three strips (6, 8 10), (6', 8?, 10') of each set provided to the side of said central portion (4) are bent towards this latter to define a beam half section comprising a first configuration of rectangular or rectangular trapezium cross-section, within which there extends in opposite directions from said common diagonal (12, 12'), or fourth strip, an internal configuration of triangular cross-section which emerges from said first rectangular configuration by way of the seventh and last strip (18, 18'), which mates with the corresponding last strip (18', 18) of the other half section. 4. A tubular beam as claimed in claim 1, characterised in that between the contacting faces of said strips which compose the two half sections there are provided adhesive zones arranged to ensure the consistency of said overall right angled or isosceles trapez lum section (4, 6', 8', 8, 6). 5. A disposable load-carrçling platform constructed with tubular beams (101) in accordance with claims 1 to 4.

Inventors: MELLI, ILARIO
Applicants: FINSEN S.P.A.
Application year: 1983
Main classification: B65D19
IPC codes: B65D19