EP0757000B1 - Blank for forming packages - Google Patents

Abstract

The foil blanks have indented bending lines (BL) formed by grooved indents (5) the bottom of which has alternating zones (8,9) of greater depth (T2) and reduced depth (T1). The zones (9) of reduced depth are defined by circular arcs (10) whose radius R is at least 1.1 mm and whose centre of curvature (M) lies on the other side of a line (l) connecting together the zones of greater depth. The greater depth is at least 40% and at most 90% of the foil thickness D. The reduced depth is at least 25% of the foil thickness. The lengths of the zones of greater depth can be between 0.5 and 5 mm. The ratio of the lengths of the zones of greater depth to that of reduced depth is between 0.5 and 1.

Description

The invention relates to a film blank for packaging, in particular for folding boxes, with embossed bending lines in the form of groove-shaped depressions which start from one foil surface and are closed at the bottom of the depressions with respect to the other foil surface, the bottom of the depressions alternating in the longitudinal direction from zones of greater depth T ₂ and zones of shallower depth T ₁ .

Such film cuts consist in particular of transparent films out Thermoplastics from the group polyethylene terephthalate (PET), Polypropylene (PP) and polyvinyl chloride (PVC), the PVC in the latter Time important because of its chlorine content from an environmental point of view has lost. However, PET and PP cause some in manufacturing additional problems that have not yet been completely mastered.

The packaging is preferably, but not exclusively for lids, but above all for folding boxes. Such Packaging enables prospective buyers an unhindered Consideration of the content, along with the packaging very much can be designed decoratively.

On folding boxes, which are usually lying flat and in piles are delivered in the packaging company, which is full automatic packaging machines is equipped, high Requirements. So the individual must lie flat Folding boxes picked up individually from a stack, into the machine inserted and erected in this, so that a cavity with a prismatic cross section, for example, is formed. The The goods in question are now in the erected folding box inserted, whereupon these at both ends by flaps or Tabs is closed. The basic requirement for this is that the Foil material on the bending lines is easily deformable without the film fields lying between the bending lines would be deformed, and that the bending lines do not produce any noticeable restoring forces. Furthermore should no sharp edges, serrations, Ridges or the like are formed. In the manufacturing process of Foil cuts should also be noted that the deformation of the foils do not become wavy in the areas of the bending lines leads between the foil fields located, a process that is at least promoted by a certain material displacement.

The foils under discussion here usually have a thickness between 0.150 mm and 1.0 mm, the mass of the film cuts has a thickness between 0.200 mm and 0.400 mm. Usually the film thickness increases with the packaging size, but not for all possible cases apply.

The switch from PVC to PET and PP has been made in the factories of Packaging and in bottling plants considerable difficulties caused.

U.S. Patent 4,064,206 is a thermal process for the Manufacture of bending lines known in the case of bending edge rulers Electrode function, against the film, against an insulating plate and pressed against a counter electrode. On the bending edge rulers and high frequency is applied to the counter tool, whereby the film material in the middle and under the bending edge rulers partially melted and laterally displaced under the embossing pressure is, whereby so-called edge beads form, which the Accompany bending edges on both sides. Such devices generate high investment and investment due to the use of high frequency Operating costs, and also the process proves to be difficult, because the temperature of the bending edge rulers despite the The presence of a regulated cooling plate is difficult to control and the device despite the presence of an insulating plate occasionally leads to voltage flashovers. The procedure in question and the device was also primarily for processing PVC films have been developed.

JP-GM 4-9345 is a foil cut according to the generic term of claim 1 and a stamping tool provided therefor so-called bending edge ruler, known in which the zones are larger and shallow depth with sharp edges connected by surfaces are aligned exactly perpendicular to the longitudinal direction of the bending line are. This form of space leads to both the inside during the bending process as well as on the outside of the bend lines to surface irregularities, damage to the contents of the packaging favor, but can also damage sensitive fabrics, if they come into contact with the outside of the packaging. Fine silk fabrics such as those for are particularly sensitive Ties are used. When touched with one Packaging can be pulled out of the silk threads. Here it should be noted that a part of such packaging as Gift pack for ties is an option. In addition, at such bending lines observed a certain risk of breakage. In this regard, it should be noted that those adjacent to the bending line Foil fields don't just have to be bent 90 ° to each other, but for the purpose of shipping partly also by 180 °, so that Foil fields lie flat on top of each other. When erecting such flat lying folding boxes must then this bend of 180 ° in one 90 ° bend, i.e. the film material is on part of the bend lines by bending back and forth in both Directions deformed. As the cause of the rough course of the bending lines and voltage peaks can be suspected for the risk of breakage arise at the sharp-edged interfaces of the surfaces and lines.

EP 0 563 781 A1 also addresses the disadvantages of Item according to JP-GM 4-9345 apart and strikes Remedy before that the surfaces of the zones of lesser depth to the Provide ends with a radius between 0.05 mm and 1.0 mm become. The document in question discloses two versions, namely one first version in which the zone of greater depth covers the entire film thickness penetrates, so the film is punched through, and a second version, at which also unites the film in the area of greater depth Remaining cross section. In both cases, however, the transition is in the area the other side of the film surface has sharp edges, and the side surfaces of the Zones of shallower depth - apart from the one mentioned Radius - at right angles and with sharp edges to the longitudinal direction of the bending line. Aside from the fact that the effect of rounding is in the range of 0.05 mm is no longer ascertainable, arises from this known Solution still a significant roughness in the area of both Foil surfaces, and the risk of breakage was not decisive decreased. For the rest, it is stated in the cited publication that the conditions beyond a radius of curvature of 1.0 mm again deteriorate, for example by the occurrence of very high Deformation forces.

The invention is therefore based on the object of cutting a film of the genus mentioned at the beginning, which is characterized by slight Producibility, low tolerances with regard to bending behavior and high resistance to kink breaks in the bending lines distinguished. In particular, the application of High frequency can be dispensed with, and the bending lines should be on both Sides of the films have a smooth course, so that a Threading is omitted, and continue to be between the Bending lines lying in the film fields do not suffer any disturbing deformation.

The object is achieved in the film cutting specified at the outset according to the invention in that the zones of shallower depth T ₁ are delimited by arcs whose radius R is at least 1.1 mm and whose center of curvature lies beyond a line which defines the zones of greater depth T ₂ connects with each other.

The arc radius is therefore larger than the maximum in question upcoming film thickness, and by the position of the invention Center of curvature M beyond the line L is achieved that the Arcs at their ends are not perpendicular to the longitudinal direction of the Bending lines run, but at an acute angle, which also the Can have a value of 0, which will be explained in more detail below becomes.

Through the spatial shape or geometry of the bending lines according to the invention easy manufacturability is guaranteed, i.e. the embossing process stabilizes with a progressive increase in imprinting forces to a certain extent itself, so that only with regard to the bending behavior small tolerances can be observed. The invention Bending lines are highly insensitive to Kink breaks, i.e. the foil fields lying on both sides of the bending lines can also be bent back and forth several times by more than 90 ° without there are breaks. The special strength against cutting the bending lines can be determined by doing the experiment makes the film cut apart along a bending line tear. There is no need to use high frequency become. The bending lines have an extreme on both sides of the foils smooth course, so that threading even when touched sensitive fabrics, such as fine silk fabrics, is avoided. The there are also none of the foil fields between the bending lines disruptive deformation, such as bulging or denting. Nevertheless, the film cuts can be easily bent without inadmissible Restoring forces occur for processing on automatic Packaging machines would be extremely disruptive. In particular, is by the inventive design of the bending lines also achieved that previously problematic processing of PET and PP made considerably easier and is improved.

The bending behavior can of course be influenced by the depths T ₁ and T ₂ and their relationship to one another. It is particularly expedient if the greater depth T _{2 is} at least 40% and at most 90% of the film thickness D. It is also advantageous if the smaller depth T _{1 is} at least 25% of the film thickness D. It is of course important to ensure that a difference in thickness remains, which is guaranteed by specifying the limit values mentioned.

The lengths A or A 'and B or B' of the zones of smaller and greater depth naturally also have an influence on the bending behavior of the bending lines. The absolute lengths A and A 'of the zones of greater depth T ₂ and the absolute lengths B and B' of the zones of less depth T ₁ can both be chosen between 0.5 mm and 5 mm, and the ratio of the lengths of the zones of greater depth the lengths of the zones of less depth can be between 0.5 and 4. At values below 1, the lengths of the zones of greater depth are smaller than the lengths of the zones of less depth. Conversely, for values over 1, the lengths of the zones of greater depth are greater than the lengths of the zones of less depth.

Even these numerical relations show that the invention Film cutting relatively insensitive to Dimensional changes is. But there are already very usable ones Ratios set when the aspect ratio A: B is in the range of 1 lies, so both zones have at least approximately the same length.

In the course of an advantageous further embodiment of the film blank according to the invention, it is particularly advantageous if the transition points between the zones of greater depth T ₂ and the zones of less depth T ₁ are rounded off concavely. It can be assumed that any stress peaks that occur during the bending process are further reduced, so that the conditions improve further.

Further advantageous embodiments of the invention Foil cutting result from the other subclaims.

Embodiments of the subject matter of the invention and for this The embossing tools required are described below with reference to FIGS to 16 explained in more detail.

Figur 1

einen flach liegenden Folienzuschnitt,

Figur 2

einen Längsschnitt durch ein erstes Ausführungsbeispiel einer Biegelinie,

Figur 3

eine erste Variante des Gegenstandes nach Figur 2,

Figur 4

eine zweite Variante des Gegenstandes nach Figur 2,

Figur 5

eine Seitenansicht eines Prägewerkzeugs für die Herstellung der Biegekante nach Figur 2,

Figur 6

einen Ausschnitt aus Figur 5 in vergrößertem Maßstab,

Figur 7

eine perspektivische Darstellung eines Ausschnitts aus Figur 5 in vergrößertem Maßstab,

Figur 8

einen Längsschnitt durch eine weitere Variante einer Biegelinie in einer Darstellung analog Figur 2,

Figur 9

eine erste Variante der Biegelinie nach Figur 8,

Figur 10

eine zweite Variante der Biegelinie nach Figur 8,

Figur 11

eine Seitenansicht eines Prägewerkzeugs für die Herstellung der Biegelinie nach Figur 8,

Figur 12

einen Ausschnitt aus Figur 11 in vergrößertem Maßstab,

Figur 13

eine perspektivische Darstellung eines Ausschnitts aus Figur 11,

Figur 14

einen Ausschnitt aus einem um 90 ° gefalteten Folienzuschnitt mit einer Biegelinie nach Figur 2,

Figur 15

einen Querschnitt durch einen Folienzuschnitt im Bereich einer Biegelinie, und

Figur 16

einen Ausschnitt aus einem um 90 ° gefalteten Folienzuschnitt mit einer Biegelinie gemäß Figur 8.

Show it:

Figure 1

a flat foil cut,

Figure 2

2 shows a longitudinal section through a first exemplary embodiment of a bending line,

Figure 3

2 a first variant of the object according to FIG. 2,

Figure 4

a second variant of the object according to Figure 2,

Figure 5

3 shows a side view of an embossing tool for producing the bending edge according to FIG. 2,

Figure 6

5 shows a detail from FIG. 5 on an enlarged scale,

Figure 7

3 shows a perspective illustration of a detail from FIG. 5 on an enlarged scale,

Figure 8

3 shows a longitudinal section through a further variant of a bending line in a representation analogous to FIG. 2,

Figure 9

8 a first variant of the bending line according to FIG. 8,

Figure 10

8 a second variant of the bending line according to FIG. 8,

Figure 11

3 shows a side view of an embossing tool for producing the bending line according to FIG. 8,

Figure 12

11 shows a detail from FIG. 11 on an enlarged scale,

Figure 13

3 shows a perspective illustration of a detail from FIG. 11,

Figure 14

3 shows a section of a film blank folded by 90 ° with a bending line according to FIG. 2,

Figure 15

a cross section through a film blank in the region of a bending line, and

Figure 16

a section of a film blank folded by 90 ° with a bending line according to FIG. 8.

In Figure 1, a film blank 1 is shown, which runs along it surrounding punching line 2 was punched out of a film. This Foil blank 1 has a number in a cross-shaped arrangement of bending lines BL. Such film cuts with different shapes Bending lines are state-of-the-art, so that further exploration is possible then superfluous.

The bending lines are designed as groove-shaped depressions 5 which 2 start from a film surface 3 and on the opposite film surface 4 are closed. As from a figure 15 emerges, the side walls 6 and 7 are at an angle β to each other, which can be 60 °, but this dimension is not critical is.

According to FIG. 2, the bottom of the depression 5 consists alternately of zones 9 of lower depth T ₁ and of zones 8 of greater depth T ₂ , the lengths of these zones 8 and 9 being designated A and B, in the exemplary embodiment according to FIG. 2 A = B is. The zones 9 of lower depth T ₁ are delimited by arcs 10, while the zones 8 of greater depth T ₂ are delimited by straight lines 11. The lines 11 all lie on a common line L, the imaginary sections of which also run through the zones 9.

As can be seen from FIGS. 14 and 15, zones 9 are more precise taken - delimited by two arcs 10 each, one represent an acute-angled section of a cylindrical surface on both sides, as can be seen from Figure 15. When bending into a position according to Figure 14 naturally deforms this section of a Cylinder surface, which is irrelevant for further considerations.

As can further be seen from FIG. 2, on the left, the center of curvature M lies beyond the line L, which connects the zones 8 of greater depth T _{2 to} one another. The expression "beyond" refers to a starting point in the film surface 3. In this case, the center of curvature M is even beyond the film surface 4, likewise seen from the film surface 3. It is thereby achieved that the ends of the circular arcs 10 extend at an acute angle α to the line L, this angle α being 45 ° in the exemplary embodiment according to FIG. Depending on the ratio of T ₁ to T ₂ and the ratio of A: B, this angle α can also assume other values, such as 60 °, or it can tend towards 0, which is discussed in more detail in connection with FIGS. 8 to 10 becomes.

In the exemplary embodiment according to FIG. 3, the ratio is A: B less than 1, and in the embodiment according to FIG. 4 this is Ratio A: B greater than 1.

Figures 5, 6 and 7 now show sections of a Embossing tool 12 for the production of bending lines according to FIG. 2. This In its initial state, the embossing tool has a cutting edge 13 which is interrupted at regular intervals by cutouts 14, the Surface a gusset-shaped section from a cylindrical surface represents, as can be seen in particular from Figure 7. As from a figure 6, the center of curvature M 'is also beyond one Cutting edge 15, which is used to generate the straight lines 11. Naturally, the cutting edge 13 is complementary to that in FIG. 2 bending line shown, i.e. the ends of the cutouts 14 go under an acute angle into the cutting edge 15 above, but below Formation of peaks at the points marked with arrows P in Figure 7.

In the exemplary embodiment according to FIGS. 8, 9 and 10, the transition points P 'between the zones 8 of greater depth T ₂ and the zones 9 of less depth T _{1 are} rounded off concavely, so that the formation of peaks is avoided at this point. Due to the circular concave transition at the transition points P ', the lengths A to A' and B to B 'change slightly depending on the radius of curvature r at these points. This radius of curvature can be between 0.1 mm and 1.0 mm. The appearance of a bending edge bent by 90 ° is shown in FIG. 16, ie the ends of the zones 9 of smaller depth T _{1 also} merge into the straight lines 11 without edges. An embossing tool 16 for the production of bending edges according to FIGS. 8 and 16 is shown in FIGS. 11, 12 and 13. This embossing tool 16 also has a cutting edge 17 with cutouts 18 through which a cutting edge 19 is interrupted. However, it is made clearly visible that roundings are provided at the transition points P ', by means of which the formation of sharp corners is avoided. It can be assumed that locally narrow flow processes during the embossing process are facilitated, as is also the avoidance of stress peaks or internal stresses in the film material. In any case, tests have shown that this not only makes the embossing process easier, but also that the film cuts have better bending behavior. The experiments have also shown that such a design of the embossing tool further reduces the risk of breakage of the film cut when bending back and forth several times.

The following table contains the most important dimensions of film cuts that have been tried and tested with success with corresponding bending lines. Bending line data Film thickness (µm) 200 250 350 600 R (mm) 1.1 1.2 1.3 3.0 T ₁ (µm) 50 80 165 380 T ₂ (µm) 175 220 315 540 DT 2nd = G (µm) 25th 30th 35 60 DT ₁ (µm) 150 170 185 220 A (mm) 1.1 1.4 1.2 2.4 B (mm) 1.0 1.2 1.2 1.8 A: B 1.1 1.17 1.0 1.33

Claims (11)

1. Foil shape for packaging, in particular for folding boxes, with embossed bending lines (BL) in the shape of groovelike recesses (5) which extend from a foil surface (3) and are closed at the bottom of the recesses (5) relative to the other foil surface (4), and the bottom of the recesses (5) is in the longitudinal direction composed of alternating of zones (8) of greater depth T₂ and zones (9) of lesser depth T₁, characterised in that the zones (9) of lesser depth T₁ are defined by arcs (10) the radius R of which is at least 1.1 mm and the arc centre (M) of which lies on the other side of a line (L) which interconnects the zones (8) of greater depth T₂.
2. Foil shape according to Claim 1, characterised in that the greatest depth T₂ is at least 40% and maximum 90% of foil thickness D.
3. Foil shape according to Claim 1, characterised in that the lesser depth T₁ is at least 25% of foil thickness D.
4. Foil shape according to Claim 1, characterised in that lengths A, A' of the zones (8) of greater depth T₂ lie between 0.5 and 5 mm.
5. Foil shape according to Claim 1, characterised in that lengths B, B' of the zones (9) of lesser depth T₁ lie between 0.5 and 5 mm.
6. Foil shape according to Claim 1, characterised in that the ratio of lengths A, A' of the zones (8) of greater depth T₂ to lengths B, B' of the zones (9) of lesser depth T₁ lies between 0.5 and 1.
7. Foil shape according to Claim 1, characterised in that the ratio of lengths A, A' of the zones (8) of greater depth T₂ to lengths B, B' of zones (9) of lesser depth T₁ lies between 1 and 4, preferably between 1 and 2.
8. Foil shape according to Claim 1, characterised in that the zones (9) of lesser depth T₁ merge into zones (8) of greater depth T₂ an acute angle "a" of between 0° and 60°.
9. Foil shape according to one or more of Claims 1 to 8, characterised in that the transitional points (P') between the zones (8) of greater depth T₂ and the zones (9) of lesser depth T₁ are concavely rounded off.
10. Foil shape according to Claim 9, characterised in that the curvature radius "r" at the transitional points (P') lies between 0.1 and 2 mm, preferably between 0.2 and 1.0 mm.
11. Foil shape according to Claim 1, characterised in that with foil thicknesses D between 200 and 400 µm the difference (D - T₁) lies between 120 and 200 µm.

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