High-strength tubular beam of folded corrugated cardboard

Claim 2

A tubular beam of folded corrugated cardboard which has a high resistance to bending and to transverse crushing comprising a single corrugated cardboard sheet (1) having its corrugations orthogonal to its longitudinal axis (2), said sheet (1) being folded back several times on itself parallel to its axis (2) to form an overall section of right angled configurations (4, 6', 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 17, 17', and which each comprise two triangular channel configurations (16', 14', 12') - (8', 10', 12'), (10, 8, 12) - (16, 14, 12) which mate along a common diagonal (12'), (12), and are mutually inverted.

Claim 3

The tubular beam as claimed in claim 1, wherein said single cardboard sheet (1), arranged to constitute said overall section of right angled configurations (4, 6', 8', 8, 6) is of constant width and indeterminate length, and comprises, on both sides of a longitudinal central portion (4), seven predetermined creasing lines (3, 5, 7, 9, 11, 13, 15) - (3', 5', 7', 9', 11', 13', 15'), of which the first four lines (3, 5, 7, 9) - (3', 5', 7', 9') are concordant with respect to their folding direction and the other three lines (11, 13, 15) - (11', 13', 15') are discordant with the preceding four lines (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 having a width substantially equal to the height of the beam (101), a fourth strip (12, 12') having a width substantially equal to the common diagonal of the triangular channel configurations, and a second strip (8, 8'), and a sixth strip (16, 16') having a width substantially equal to one half the width of the beam.

Claim 4

The tubular beam as claimed in claim 1, wherein the first three strips (6, 8, 10), (6', 8', 10') of each set provided on each side of said central portion (4) are bent towards the latter to define a beam half section comprising a first configuration of rectangular cross-section, within which there extends in opposite directions from said common diagonal (12, 12'), as a fourth strip, an internal configuration of triangular cross-section which emerges from said first rectangular configuration by way of the seventh and last strips (18, 18'), which mate with the corresponding last strip (18', 18) of the other half section.

Claim 5

The tubular beam as claimed in claim 1, wherein 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 configurations (4, 6', 8', 8, 6).

Claim 6

The tubular beam of claim 1 wherein the sheet contains fifteen longitudinal fold lines which continually fold inwardly toward each other at right angles and acute angles to define two adjacent mirrored square cornered sections, each containing a diagonal member which subdivides each square cornered sections into said two mutually inverted triangular channels.

Claim 7

A tubular beam of folded corrugated cardboard which has a high resistance to bending and to transverse crushing comprising a four, square cornered member, longitudinally subdivided into two, four square cornered members, each of said two members being further subdivided by a diagonal into two, mutually inverted, triangular channels, whereby the tubular beam has one side of substantially one thickness, three sides of two thicknesses, a longitudinally subdividing member of four thicknesses and two diagonal members of one thickness.

Claim 8

A tubular beam of folded corrugated cardboard which has a high resistance to bending and to transverse crushing comprising a four, square cornered member, longitudinally subdivided into two, four square cornered members, each of said two members being further subdivided by a diagonal into two, mutually inverted, triangular channels, whereby the tubular beam has one side of substantially one thickness, three sides of two thicknesses, a longitudinally subdividing member of four thicknesses and two diagonal members of one thickness.