Panel interlocking arrangement

Abstract: Panel interlocking means for securing together a pair of panels in overlapping relationship includes a locking tab (T) struck from one of the panels and arranged to be driven through a locking aperture struck from the other panel. The opposed lateral edges (E1,E2) of the locking tab have deformable marginal portions formed by cut lines (C1,C2) which comprise angularly related portions (P1,P2) of which one portion (P) meets its associated lateral edge of the locking tab at an angle of substantially 90 degrees.

Description: This invention relates to a panel interlocking arrangement and to cartons, particularly foldable wrappers, having such interlocking means. Known wrappers often comprise a blank which has a top wall panel, two side wall panels and two base panels hinged together by means of fold lines, one base panel having locking tabs which can be folded up from said one base panel for engagement in associated openings of the other base flap portion, the locking tabs then being supported in position by retaining tabs which are folded up from the edges of the openings. The articles which are to be packaged with such foldable wrappers usually have in fact approximately the same dimensions. In practice however, the dimensional tolerances of the articles which arise within an individual package are relatively high. This applies especially to multi-way bottles, because numerous types of bottles whose dimensions are in fact similar but not absolutely identical, are in circulation. Manufacturing tolerances are not the only reason for this, but in particular there is also the fact that there has not been hitherto an adequate standardisation for bottle dimensions. Even after the introduction of a standard for the dimensions of bottles, bottles which differ from this standard and which have to be packaged with foldable wrappers are still in circulation. In our co-pending European Patent Application E-A-0 275 200 a panel interlocking arrangement for cartons is described and claimed. In this interlocking arrangement, an adjustable locking tab includes a plurality of deformable marginal portions defined by successive cut lines in the marginal edge portions of the locking tab. These deformable edge portions are selectively deformed by engagement of the tab with lateral edges of a cooperating locking aperture at a location dependent upon the extent to which the locking tab is driven into the locking aperture, whereby the locking tab may be locked in a plurality of different positions. However, it has been found that difficulties have arisen in the production of a satisfactory die cutting rule arrangement for forming the locking tab described above and further attention was necessary to determine the form of the successive cut lines. One aspect of the present invention provides, in panel interlocking means for securing together a pair of panels in overlapping relationship comprising a locking tab struck from one of said panels and an elongate locking aperture provided in the other said panels and arranged to receive and retain said locking tab, said locking tab being hinged to said one panel at a base of the locking tab and having opposed lateral edges, said locking aperture comprising spaced lateral edges which are generally aligned with the lateral edges of said locking tab when the locking tab is engaged; within the locking aperture, the locking tab which has at least one of its lateral edges formed with a plurality of deformable marginal portions which selectively are deformed by engagement with the lateral edges of the locking aperture at a location dependent upon the extent to which said locking tab is driven into said locking aperture whereby said locking tab may be locked in the locking aperture in a plurality of selected positions, characterized in that said deformable marginal portions are defined by a succession of cut lines each of which has a first portion which meets its associated lateral edge of the locking tab at an angle of substantially 90 degrees and has a second portion contiguous therewith which is directed towards said base of the locking tab at an angle greater than 90 degrees with respect to said first portion. According to a feature of the aspect of the invention the angle subtended between the first and second portions of each of said cut lines may be substantially 135 degrees. Another aspect of the invention provides a die cutting rule arrangement for forming a locking tab according to either of the two immediately preceding paragraphs comprises a single peripheral cutting rule to cut the outline periphery of said locking tab and a succession of spaced transverse cutting rules extending between opposed lateral edges of said peripheral cutting rule each of said transverse rules having a cutting edge at at least one of its lateral extremities which cutting edge has a first portion which meets the adjacent cutting edge of said peripheral rule at an angle of substantially 90 degrees and a second portion inclined with respect to said first portion. An embodiment of each aspect of the invention wil now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a schematic view of a locking tab having marginal edge cut lines according to the invention, and Figures 2 and 3 are schematic plan and cross-sectional views respectively of a die-cutting rule arrangment for the locking tab illustrated in Figure 1 in which Figure 3 is a view along the line 3-3 in Figure 2. Referring to Figure 1, the locking tab "T" has lateral edges E1 and E2, marginal portions of each of which are formed with a succession of cut lines C1 and C2 respectively. Each cut line has a first portion P1 which meets the associated lateral edge of the tab at an angle of 90 degrees and a second contiguous portion P2 which is directed towards the hinged base 'B' of the tab at an angle which is greater than 90 degrees with respect to the first portion. In the arrangement shown, the angle 'a' subtended between the first and second portions of each cut line is substantially 135 degrees. Thus, the first portions are parallel to the hinged base whereas the second portions are convergent towards the base of the tab. Referring now to figures 2 and 3, a single cutting rule R3 is formed for each pair of aligned marginal cut lines adjacent the opposed lateral edges of the lock. Thus, each cutting rule R3 has opposed cutting edges e1 and e2 which meet the main peripheral rule R4 at substantially 90 degrees thereby allowing the cutting edges of rules R3 and R4 to mate correctly at their adjoining faces. The central portion of each cutting rule R3 is recessed at Pc so that no cut is made across the central portion of the locking tab. Each cutting rule R3 is formed with a slot 'S' extending from the end thereof opposite its cutting edges centrally of the rule which receives a ridge portion Rp of the die cutting plate P1 when the rule is embedded in the plate. Thus, the rule P3 is of inherently strong configuration and the central plate ridge enhances the rigidity of the fixture of the rule in a die cutting plate. It is envisaged that locking tabs may be required which have marginal cut lines along only one of its lateral edges in which case the recessed portion Pc of the rule, is extended to eliminate one of its cutting edges.

Claims: In panel interlocking means for securing together a pair of panels in overlapping relationship comprising a locking tab (T) struck from one of said panels and an elongate locking aperture provided in the other of said panels and arranged to receive and retain said locking tab, said locking tab being hinged to said one panel at a base (B) and having opposed lateral edges (E1, E2), said locking aperture comprising spaced lateral edges which are generally aligned with the lateral edges of said locking tab when the locking tab is engaged within the locking aperture, the locking tab (T) which has at least one of its lateral edges (E1,E2) formed with a plurality of deformable marginal portions (C1,C2) which selectively are deformed by engagement with the lateral edges of the locking aperture at a location dependent upon the extent to which said locking tab is driven into said locking aperture whereby said locking tab may be locked in the locking aperture in a plurality of selected positions, characterized in that said deformable marginal portions are defined by a succession of cut lines each of which has a first portion (P1) which meets its associated lateral edge of the locking tab at an angle of substantially 90 degrees and has a second portion (P2) contiguous therewith which is directed towards said base (B) of the locking tab at an angle greater than 90 degrees with respect to said first portion. A locking tab according to Claim 1, further characterized in that the angle subtended between the first and second portions of each of said cut lines is substantially 135 degrees. A die cutting rule arrangement for forming a locking tab according to Claim 1 comprises a single peripheral cutting rule (R4) to cut the outline periphery of said locking tab and a succession of spaced transverse cutting rules (R3) extending between opposed lateral edges of said peripheral cutting rule; each of said transverse rules (R3) having a cutting edge at at least one of its lateral extremities which cutting edge (e1,e2) has a first portion which meets the adjacent cutting edge of said peripheral rule at an angle of substantially 90 degrees and a second portion inclined with respect to said first portion.

Inventors: HEPWORTH JOHN, MARIE PHILIPPE, MUELLER ROLF, HEPWORTH, JOHN, MARIE, PHILIPPE, MUELLER, ROLF
Applicants: MEAD CORP, THE MEAD CORPORATION
Application year: 1990
Main classification: B65D71
IPC codes: B65D71, B65D5, B65D75