AU2005201630B2 - Improved die rule design - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): VISY R & D PTY LTD Invention Title: IMPROVED DIE RULE DESIGN The following statement is a full description of this invention, including the best method of performing it known to me/us: - 2 IMPROVED DIE RULE DESIGN Field This invention relates to improvements in die rule designs for forming shaped cuts in paperboard container 5 panels by means of which the container may be manually opened without the use of a tool such as a knife. Background Many containers made of cardboard or corrugated 10 cardboard are formed with spaced cuts and "nicks" (uncut board) along which the board may be manually torn to open the container. In most cases, the shaped cuts define a strip of board which is gripped at one end and torn from the container. A typical arrangement of this sort 15 employing a well-known die rule design is illustrated in U.S. Patents 5,582,345 and 4,274,580. In other cases, a line or lines of short spaced perforations defines a tear line, such as 7 in the abstract of publication no. WOOO/63083. 20 Object and Summary It is an object to provide an improved die rule design for forming a line of spaced cuts which allow the board to be ruptured along the line by the application of 25 an inwardly directed force rather than the usual outwardly directed tearing force. In one aspect, the invention provides a die rule design for forming an array of spaced cuts in a cardboard 30 wall panel, said cuts including a first portion comprising at least two substantially linear portions separated by an uncut portion of the wall panel, end portions extending angularly from the outer ends of said linear portions, said end portions in said array of spaced cuts being 35 adjacent each other and separated by uncut portions of the wall panel, said uncut portions separating said end portions being laterally offset from an extending H:\julial\keep\Speci\P56079 std.doc 18/04/05 3 substantially parallel to the linear portions to increase the structural integrity of the wall panel, said uncut portions being of such dimensions to allow rupture by a digitally applied force applied to the uncut portions, the linear 5 portions and the angular portions being joined by a curved portion. By including an uncut portion in the first portion and offsetting the uncut portions between the adjacent end portions of the angular cut portions, the structural 10 integrity or strength of the wall panel board is improved compared to board perforated by a linear array of spaced linear cuts, or an array of known die rule design cuts of the type referred to above. To improve the strength of the panel region including 15 the spaced linear portions, linear portions may be inclined so that adjacent linear portions are not in a straight line. -Such an arrangement slightly increases the strength of the wall portion to avoid inadvertent opening. The angular portions may extend at an included angle to !0 the linear portion of the order of 1350. In such an arrangement, the adjacent ends of the angular portions are arranged so that extensions of said ends intersect at about 90' to maximise the strength of the uncut portion of the wall panel at this position. 25 In another embodiment, the linear portions have a further linear or slightly curved portion spaced from their ends by uncut portions. In another aspect, the invention provides an easy-open container, and the blank for forming same, formed with an 30 array of spaced cuts as defined in the preceding paragraphs. Various arrays of spaced cuts may be used - 4 depending on the nature of the container and its contents, and several embodiments are detailed further below. While the invention is primarily applicable to 5 corrugated board containers and their blanks, it may also be applied to other cardboard containers and their blanks. Brief Description of Drawings In order that the invention may be more readily 10 understood several embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 illustrates a container blank having arrays 15 of spaced cuts formed by a die rule in accordance with the improved design; Figure 2 illustrates the blank of Figure 1 with arrays of spaced cuts formed by a modified die rule 20 design; Figure 3 illustrates a further blank with an array of cuts in accordance with a further modified die rule design; and 25 Figure 4 illustrates enlarged Details A, B and C from Figures 1 to 3 respectively. Description of Embodiments 30 Referring firstly to Figures 1 and 4 of the drawings, Figure 1 illustrates a container blank of corrugated board having side panels 1 and 2 and top and bottom panels 3,4 and closing side flaps 5, 6, 7 and 8 and a closing end flap 9 separated by fold lines F. 35 Extending across the panels 1 and 2 and the side flaps 6 and 8 is an array 10 of die cuts of similar shape H:\julial\keep\Speci\P56079 std.doc 18/04/05 - 5 spaced by uncut portions of the board defining the wall panels. As illustrated most clearly in Detail A Figure 4, the 5 array 10 comprises a multiplicity of spaced pairs of cuts 11 and 12 of the same shape but opposite orientation formed in accordance with the die rule design embodying the invention. The cuts 11 and 12 are separated by a "nick" or uncut portion 13 and adjacent pairs of cuts 11 10 and 12 are similarly separated by nicks or uncut portions 14. Each cut 11 and 12 comprises a linear portion 15 and an angular end portion 16, extending at the angle 15 illustrated and connected to the linear portion 15 by a curved portion 17. The pairs of cuts 11, 12 are typically about 40 mm wide and about 5 mm deep with uncut portions 13 and 14 20 about 4 mm wide. The angular portions 16 extend at an included angle of about 1350 so that extensions of the ends intersect at about 90* to maximize the strength of the portions 14 and the curved portions 17 have a radius of about 10 mm. 25 In use, the uncut portions 13 and/or 14 are ruptured by the application of finger or thumb pressure directed inwardly of the container, and to this end the array 10 is positioned so that at least some of the uncut portions 13, 30 14 are aligned with voids or weak points inside the container. Once several of the nicks or uncut portions 13, 14 are broken, the top of the container is able to be removed quite freely. 35 The location of the uncut portions 14 between the ends of the angular portions 16 means that these portions are offset from the linear portions 15 thereby increasing H:\julial\keep\Speci\P56079 std.doc 18/04/05 - 6 the structural integrity of the wall panels against inadvertent opening. Figure 2 illustrates the same blank as in Figure 1 in 5 which the side panels 1, 2 and side flaps 7, 8 are formed with linear arrays 10' of modified cuts in accordance with the design illustrated in Detail B of Figure 4. The modified die cut arrays 10' include die cuts 11' and 12' similar to the die cuts 11 and 12 of Figure 1, but having 10 shorter linear portions 15', which are spaced by a further almost linear die cut 18 which is slightly inwardly curved in the direction of the angular portions 16' of the die cuts 11' and 12', leaving "nicks" or uncut portions 13' and 14' between the adjacent die cuts 11' and 12' and 18. 15 The linear or slightly curved portions 18 of the die cuts are not in a straight line and this slightly increases the strength of the wall panel in these positions. In the embodiment of Figure 3, the array of cuts 10" 20 extends across the side walls Si and S2 and angularly across the front and rear walls F and R as illustrated. The cuts forming the array 10" are similar to the cuts in Figure 1 but modified as shown in Detail C of Figure 4, by angling the linear portions 15" in the direction of the 25 angular portions 16" so that the linear portions 15" are not in a straight line. This slightly increases the strength of the panel at these positions. In the arrangement illustrated in Figure 3, the cuts 30 which extend across fold lines FO are modified so that nicks or uncut portions 13", 14" are positioned on either side of the fold lines FO, as illustrated. The cuts are stretched or slightly lengthened or reshaped to accommodate corners formed at the fold lines, again as 35 illustrated. H:\julial\keep\Speci\P56079 std.doc 18/04/05 It will be appreciated that the above and other blank designs incorporating various combinations of cuts according to the die rule designs described above may be devised without departing from the spirit or scope of the 5 invention defined above. The type of cut designs selected will depend on the nature of the product being packaged in the container and the availability of voids or weak points within the container at which nicks may be broken by the application of inward pressure applied digitally by finger 10 or thumb. While the die rule designs embodying the invention have been designed for use in the above illustrated manner, it will be appreciated that the same or similar 15 die rule designs may be utilised to define tear strips or other forms of easy opening means. H:\julial\keep\Speci\P56079 std.doc 18/04/05

Claims (13)

1. A die rule design for forming an array of spaced cuts in a cardboard wall panel, said cuts including a first portion comprising at least two substantially linear 5 portions separated by an uncut portion of the wall panel, end portions extending angularly from the outer ends of said linear portions, said end portions in said array of spaced cuts being adjacent each other and separated by uncut portions of the wall panel, said uncut portions separating 10 said end portions being laterally offset from and extending substantially parallel to the linear portions to increase the structural integrity of the wall panel, said uncut portions being of such dimensions to allow rupture by a digitally applied force applied to the uncut portions, said 15 linear portions and said end portions being joined by curved portion.

2. The die rule design of claim 1 wherein the end portions are of substantially equal length.

3. The die rule design of claim 1 or claim 2, !0 wherein the spaced linear portions are inclined towards the uncut portions separating them so that the spaced linear portions are not in a straight line.

4. The die rule design of claims 1, 2 or 3, wherein the angular portions are inclined towards the adjacent end 25 portions in the array such that extensions of said end portions intersect at about 900.

5. The die rule design of claim 4, wherein the angular portions extend at an included angle to the linear portion of the order of 1350. 30

6. The die rule design of any preceding claim, further including a further substantially linear cut portion between the ends of the linear portions and spaced by uncut 9 portions of the wall panel.

7. The die rule design of claim 6, wherein the further substantially linear portion is curved in the direction of the end portions. 5

8. The die rule design of claim 1, substantially as hereinbefore described with reference to Figure 1 and Detail A of Figure 4 of the accompanying drawings.

9. The die rule design of claim 3, substantially as hereinbefore described with reference to Figure 3 and Detail 10 C of Figure 4 of the accompanying drawings.

10. The die rule design of claim 7, substantially as hereinbefore described with reference to Figure 2 and Detail B of Figure 4 of the accompanying drawings.

11. A cardboard blank for forming an easy-open [5 container incorporating one or more of the die rule designs defined in any one of claims 1 to 10.

12. A blank for forming an easy-open container substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings. 20

13. An easy-open container formed from a blank as defined in claim 11 or claim 12.