WO2008044190A1

WO2008044190A1 - Box with double-scored folds

Info

Publication number: WO2008044190A1
Application number: PCT/IB2007/054083
Authority: WO
Inventors: Hans Weber
Original assignee: Amcor Rentsch Rickenbach AG
Current assignee: Amcor Specialty Cartons Switzerland GmbH
Priority date: 2006-10-13
Filing date: 2007-10-08
Publication date: 2008-04-17
Anticipated expiration: 2009-04-13

Abstract

Box made of foldable sheet material (1), comprising one or more folded edges each formed by a single fold (2) in the sheet material, characterized in that said fold (2) is formed with the sheet material folded about a double-scored line that comprises two parallel score lines (3,4) in the sheet material obtainable by cutting or creasing the sheet material, wherein the parallel score lines (3,4) are disposed closely adjacent to one another on either side of a central ridge-like partition (5) of remnant sheet material, and the sheet material (1) is folded by means of the two parallel score lines with a single fold (2) about the two sides of the central partition (5).

Description

BOX WITH DOUBLE-SCORED FOLDS

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to the packaging industry. More specifically, the present invention relates to a box made of foldable sheet material, in which folded edges are formed by a double-scored line.

Description of the Prior Art

Folding lines in prior art boxes are traditionally made by single-scoring, by which the foldable sheet material is deformed along the folding line (stretching the fiber structure of the foldable sheet material) and is clearly perceptible as a deep, engraved groove. For example, WO

02/064452 discloses a box with rounded or chamfered edges, formed by a plurality of scored lines, each of said scored line corresponding to one fold in the foldable sheet material . According to the prior art, the deformation of the foldable sheet material is carried out by flat-bed processing using a cutting and creasing form. This form is composed of a plate in which a defined pattern of all lines which are to be cut or creased are incised as slits into the plate itself by means of a laser, a water jet or other mechanical processes. The plate can be made of bonded wood, plastic, metal or a compound of these materials. The scoring rules which are fitted into the plate are made of strip steel specially fabricated for this particular purpose. The customary width of these rules is 2-3 points (1 point = 0.3538 mm) . In most cases, the height of the scoring rule is the same as that of the cutting knives. However, this height can sometimes vary slightly depending upon the type of foldable sheet material used and the strength of score required. The top edge of the rule which is in contact with the foldable sheet material is rounded, or beveled and rounded. The cutting and creasing form is pressed onto the front side of the foldable sheet material (the printed, coated side) . On the underside, it is necessary to have a counter make-ready, which has grooves in the areas of the scoring rules. These scoring grooves are directly recessed into the metal counter plate by means of milling, eroding or etching. Further possibilities are the glueing on of a partial counter make-ready comprised of milled plastic or the glueing on of scoring grooves, such as disclosed in EP1502729. The scoring groove width must be at least twice the foldable sheet material caliper plus the width of the scoring rule. The depth of the scoring groove is usually so determined that the foldable sheet material is not crushed or its surface broken.

This method of scoring can also be carried out in a rotary process using a cassette in which two cylinders are mounted, a positive and a negative cylinder, made of steel and which rotate against each other with the foldable sheet material passing in between. In most cases, the creasing and the cutting are carried out using two separate sets of cylinders - one set for creasing and on set for cutting. The positive creasing cylinder has those elements which are to be scored either directly cast out of the cylinder or screwed on to the cylinder as scoring segments. The negative cylinder contains the grooves which likewise are directly cast or are on the cylinder as groove segments . The disadvantage of this scoring, by flat-bed as well as by rotary, is that there is a relatively wide scoring on the foldable sheet material which must be kept under control so that the fold maintains its accuracy. The performance of the fold also depends on the accuracy of the centering of the scoring rule in the groove on the counter tool. A further disadvantage can be seen in the in-line process printing, cutting and creasing from foldable sheet material reels - where the foldable sheet material tends to cling in the scores which can have a negative effect on production output. Furthermore, in the case of faulty foldable sheet material manufacturing lots, there are often problems with twisting, curling, bowing or warping of the foldable sheet material .

Alternative methods used for generating boxes with folding lines include:

- Generating folding lines by using a scoring knife on the front side of the foldable sheet material, instead of on the underside of the foldable sheet material.

The areas to be folded are nicked into the foldable sheet material to a depth of 50% of the foldable sheet material caliper by means of a cutting rule. This scoring knife is also mounted in the cutting form and is pressed against a counter plate. The advantage of this knife scoring system is being able to achieve a clean folding line in the exact position required. The disadvantage is a weakening of the foldable sheet material and the formation of an unprinted bevel in the coloring of the foldable sheet material. Depending on which type of foldable sheet material is used, there is a danger that, by mechanical operations, delaminating of the foldable sheet material surface could occur in the areas of the knife score lines.

- Generating folding/creasing lines by method of perforation: By using a cutting knife with defined cut-gaps, a perforation is made in the foldable sheet material. These perforations can fully or just partly cut through the foldable sheet material.

In view of the prior art, there is a need for a box with folded edges in which folds are made with greater accuracy than with prior art methods and hence have better overall appearance, allowing shorter make-ready times and higher production output with in-line processing, and in which twisting and curling effects of the foldable sheet material are reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

- Fig. 1 is a transversal view of a ready-to-fold sheet of foldable material according to the invention, comprising a double-scored line obtained by cutting the sheet material.

- Fig. 2 is a transversal view of a ready-to-fold sheet of foldable material according to the invention, comprising a double-scored line obtained by creasing the sheet material. - Fig. 3 is a transversal view of a sheet of foldable material folded at substantially 90 degrees, comprising a double-scored line obtained by cutting the sheet material.

- Fig. 4 is a transversal view of a sheet of foldable material folded at substantially 180 degrees, comprising a double-scored line obtained by creasing the sheet material. - Fig. 5 is a first cutting form/counter plate combination used to manufacture a box according to the invention .

- Fig. 6 is an alternative cutting form/counter plate combination used to manufacture a box according to the invention .

DESCRIPTION OF THE INVENTION

The present invention provides a box made of foldable sheet material (1), comprising one or more folded edges each formed by a single fold (2) in the sheet material, characterized in that said fold (2) is formed with the sheet material folded about a double-scored line that comprises two parallel score lines (3,4) in the sheet material obtainable by cutting or creasing the sheet material, wherein the parallel score lines (3,4) are disposed closely adjacent to one another on either side of a central ridge-like partition (5) of remnant sheet material, and the sheet material (1) is folded by means of the two parallel score lines with a single fold (2) about the two sides of the central partition (5) . Preferably, said parallel score lines (3,4) are disposed inside the fold (2) .

In an embodiment of the invention, the centre-to-centre distance between the parallel score lines (3,4) is between 100 % and 300 % of the thickness of the foldable sheet material ( 1) .

In a further embodiment of the invention, the sheet material (1) forms an angle of approximately 90° across the fold (2) .

The score lines (3,4) of the box according to the invention may have an approximately V-shaped cross-section, an approximately U-shaped cross-section, or any other appropriate shape.

The present invention also provides a pre-scored sheet of foldable sheet material (1) for forming a box according to any preceding claim, the sheet material comprising at least one fold (2) each constituted by a double-scored line that comprises two parallel score lines (3,4) in the sheet material obtainable by cutting or creasing the sheet material, wherein the parallel score lines (3,4) are disposed closely adjacent to one another on either side of a central ridge-like partition (5) of remnant sheet material, and the sheet material (1) is foldable by means of the two parallel score lines with a single fold (2) about the two sides of the central partition (5).

According to one embodiment of the invention, the weakening of the material structure of the foldable sheet material takes place on the reverse side and is only faintly or not at all perceptible on the front printed side. This is achieved by using two side-by-side parallel scoring or creasing rules. The spacing between the scoring or creasing rules is dependent on the type of foldable sheet material in use and must be individually determined.

The box according to the invention may be manufactured by using various cutting form/counter plate combinations.

In a first method depicted in Fig. 5, the foldable sheet material is scored or creased on the reverse side to weaken the folding lines and simultaneously pattern-cut from the reverse side to form the contour of the pack. For this process, a cutting form (11) comprising cutting knives is needed. The double-scoring rules (9) or double-creasing rules (10) may be fitted in the same cutting form (11) . The individual creasing or scoring rules (9,10) may be placed directly side by side or be separated by a spacing blank (12). The operation is carried out against a flat counter plate (13). The disadvantage of this processing procedure is that most production installations are not designed for this method of cutting from the reverse side of the board, with the result that extensive adaptations of existing tooling would have to be made. The advantage is that no tight registering of the cutting form to the counter plate is necessary, which substantially reduces make-ready time.

An alternative method for obtaining the box according to the invention is depicted in Fig. 6. The double-scoring rules (16) or double-creasing rules (17) are incorporated into the counter plate (13) instead as into the cutting form. This can be done by direct milling into the counter plate or by the placing of steel-made, prefabricated double-scoring rules (16) or double-creasing rules (17) into corresponding recesses in the counter plate. The cutting form contains cutting knives (8) for the contour cutting of the packaging in the same way as described in the present day cutting and creasing technology. Partial counter pressure is needed in the area of the folding lines. This can be in the form of a steel rule (15), as a counterpart, which is wider on both sides than the double- scoring rules (16) or double creasing rules (17) so as to compensate for slight deviations between the cutting form (11) and counter plate (13) . In place of the steel rules (15) as a counterpart, it is possible to mount other hard materials (18), partially, on the cutting form in the areas of the double-scoring rules (16) and double-creasing rules (17) . This technology can be used on existing machine configurations .

Claims

1. Box made of foldable sheet material (1), comprising one or more folded edges each formed by a single fold (2) in the sheet material, characterized in that said fold (2) is formed with the sheet material folded about a double-scored line that comprises two parallel score lines (3,4) in the sheet material obtainable by cutting or creasing the sheet material, wherein the parallel score lines (3,4) are disposed closely adjacent to one another on either side of a central ridge-like partition (5) of remnant sheet material, and the sheet material (1) is folded by means of the two parallel score lines with a single fold (2) about the two sides of the central partition (5).

2. Box of claim 1, wherein said parallel score lines

(3,4) are disposed inside the fold (2) .

3. Box of claim 1 or 2, wherein the centre-to-centre distance between the parallel score lines (3,4) is between 100% and 300% of the thickness of the foldable sheet material (1).

4. Box of any preceding claim, wherein the sheet material

(1) forms an angle of approximately 90° across the fold (2) .

5. Box of any preceding claim, wherein each score line (3,4) has an approximately V-shaped cross-section.

6. Box of any one of claims 1 to 4, wherein each score line (3,4) has an approximately U-shaped cross- section .

7. A pre-scored sheet of foldable sheet material (1) for forming a box according to any preceding claim, the sheet material comprising at least one fold (2) each constituted by a double-scored line that comprises two parallel score lines (3,4) in the sheet material obtainable by cutting or creasing the sheet material, wherein the parallel score lines (3,4) are disposed closely adjacent to one another on either side of a central ridge-like partition (5) of remnant sheet material, and the sheet material (1) is foldable by means of the two parallel score lines with a single fold (2) about the two sides of the central partition (5) .