WO1999029496A1

WO1999029496A1 - Method for producing blanks with fold lines

Info

Publication number: WO1999029496A1
Application number: PCT/EP1998/008091
Authority: WO
Inventors: Peter Marbach
Original assignee: Karl Marbach Gmbh & Co.
Priority date: 1997-12-12
Filing date: 1998-12-11
Publication date: 1999-06-17

Abstract

The invention relates to a method for producing blanks with fold lines for folded packaging, made from a sheet of material (20). The fold lines are formed by contactless removal of material from said sheet of material (20). The fold lines are made by removing material from the second surface (19) of the sheet of material in a contactless manner when said sheet of material (10) is provided with a first decorated surface (17) which is turned outwards once the packaging is assembled and a second normally untreated surface which is turned inward once the packaging is assembled. As a result, the fold line cannot be seen when the folding packaging is assembled and deformation of the decorated image is avoided.

Description

METHOD FOR PRODUCING FOLDED LINES

The invention relates to a process for the production of blanks provided with fold lines for the production of folded packagings from a sheet of material, which in particular has a decorated first surface, which faces outwards after the fold packagings have been produced, and a second, normally untreated surface, which shows inside after the folding packaging has been made.

Steel strip punching and creasing tools, such as are known for example from WO 91/03358, are currently used to produce blanks provided with folding lines from a sheet of material made of cardboard or corrugated cardboard. Such a band steel punching and creasing tool is arranged between a pressure plate and a counter-punching plate of a punching machine and has a carrier plate, on the underside of which punching lines and creasing lines are provided which extend in the direction of the counter-punching plate, the free end of the punching lines projecting somewhat further than the free end of the crease lines.

To produce the blanks, for example, a sheet of cardboard is placed on the counter-punching plate so that the decorative side of the sheet faces the punching and creasing lines, and the printing plate with the carrier plate is moved downward until the free ends of the punching lines cut through the sheet have and have come into contact with the counter-punching plate. The round ones at their free ends Creasing lines compress the sheet material on the decorative side so that a permanently deformed folding line remains, along which the blank can be folded during the manufacture of a package.

However, the fold line remains visible on the outside of the packaging after folding and distorts the decor. A clear bulge is visible on the inside of the packaging.

With the well-known steel stamping and creasing tools, very high cycle times can be achieved. However, the preparation of the band steel punching and creasing tool requires a considerable amount of time, since all the punching and creasing lines have to be attached to the carrier plate in such a way that the punching lines simultaneously touch the counter-punching plate and their lines compress the sheet as required. Since the punching lines and creasing lines come into contact with the sheet material during the punching processes, the cutting lines and creasing lines can wear out with a high number of punching processes, which necessitates a new adjustment of the band steel punching and creasing tool. In addition, there are high dynamic forces in a band steel punching and creasing tool, which lead to a deformation of the band steel punching and creasing tool, which must also be compensated for. Since the punch lines generally wear out faster than the crease lines, the sheet material is compressed more after the punch lines wear out because the crease lines can move further down. The fold lines are therefore not constant. In addition, with a band steel punching and creasing tool, only sheets with a certain thickness can be processed after trimming. A new dressing is required for sheets with a new thickness. The invention has for its object to provide a method with which can be provided with fold lines blanks for packaging from a sheet of material reliably with constant quality so that the packaging made from the blanks have a precisely formed folding edge.

This object is achieved by a method for producing blanks for folding packaging provided with folding lines from a sheet of material, in which the folding lines are formed by contactless removal of material from the sheet of material.

The expression "contactless" is to be understood such that a tool does not come into direct contact with the material sheet, but rather the formation of fold lines over a medium, such as e.g. Laser beams, water jets, dry ice or compressed air are used.

Since the folding lines are formed in the method according to the invention by removing material from the sheet of material and not by compressing the material, as was previously the case, the shape and depth of the grooves can be selected independently of the material thickness. Since the folding lines are formed without contact, there is no wear on tools.

If the material sheet has a decorated first surface, which faces outwards after the folding packaging has been produced, and a second, normally untreated surface, which points inwards after the folding packaging has been produced, the folding lines are formed by contactless removal of material from the material sheet on the second surface. The fold line is therefore not visible on the outside of the packaging after the packaging has been folded. A sharp folded edge can be formed that do not distort the decor.

The folding lines are preferably computer-controlled by means of a laser beam. A CO ₂ laser with a galvo deflection head is preferred. This creates the possibility of entering the necessary data for the folding lines as well as for cuts in the material sheet in advance offline into a computer, so that no preparation times are required. A high degree of flexibility is achieved, which makes it possible to switch between producing different blanks in the shortest possible time.

If the laser beam is used to form the cuts on the second normally untreated surface of the sheet of material, no traces of smoke and therefore no blackening are visible on the first surface provided with the decor.

In the case of a sheet material that tends to form little smoke, the laser beam can be moved along a straight line on the material sheet to form a fold line at a predetermined speed and a relatively large predetermined thickness.

However, if the material tends to form a high amount of smoke and thereby blacken it is advisable to move the laser beam several times along a straight line on the material sheet in order to form a fold line at a predetermined speed and a relatively low dose of predetermined thickness in order to remove the material in layers.

If the laser beam to form a fold line each with a predetermined speed and a predetermined strength along at least two parallel straight lines If the material sheet is moved, fold lines of different cross-sectional contours or multi-groove fold lines can be formed.

Instead of using a laser, the computer-controlled formation of fold lines can also take place using compressed air, dry ice or water jets, depending on the material of the material sheet to be processed.

Embodiments of the invention are explained below with reference to the drawings. Show it:

1 shows a blank from a sheet of material,

2 shows a sheet of material with several blanks,

3 schematically shows a processing device for producing grooved blanks from a sheet of material,

4 shows schematically a plant for producing grooved blanks from material sheets,

5 schematically shows the structure of a laser device,

6 schematically shows the effect of a flat field lens,

7a is a partial cross section of a sheet in the area of a V-shaped fold line,

7b shows the fold line area of the sheet of FIG. 7a after 90 "folding,

8a is a partial cross section of a sheet in the area of a W-shaped fold line,

8b shows the fold line area of the sheet of FIG. 8a after 90 "folding,

9a is a partial cross section of a sheet in the area of a three-groove fold line,

9b shows the fold line area of the sheet of FIG. 9a after 90 "folding,

10a shows a partial cross section of a sheet in the area of a trapezoidal folding line,

10b shows the fold line area of the sheet of FIG. 10a after a 90 ° fold, The blank shown in Fig. 1 as a simple example is used to produce a box open at the top, which is printed on the outside. It has two parallel transverse grooves 11, 13, which extend between the two long sides of the blank 10. There are also two parallel longitudinal grooves 14, 15, which extend perpendicular to the transverse grooves 11, 13 between them. A cut is in each case in extensions of the longitudinal grooves 14, 15

12 is provided, which extends from the corresponding transverse groove 11,

13 extends to the transverse edge of the blank 10.

2 shows, several blanks 10 are cut out from a sheet of material 16, for example from cardboard or corrugated cardboard. In the embodiment of FIG. 2, six rows, each with three blanks, are provided.

The processing device shown in FIG. 3 can be used to produce the blanks 10 shown in FIG. 1 from the material sheet 16 shown in FIG. 2. It has a flat processing table 18, on the horizontal surface of which a sheet of material 20 is placed, which consists, for example, of cardboard or corrugated cardboard and one with a decor, such as has a printed first surface 17 and an untreated second surface 19. The first surface 17 faces the processing table 18.

The material sheet 20 can be fixed locally by clamping from two sides, a frame or by means of a vacuum device.

Above the material sheet 20, a laser device 26 with a C0 ₂ laser is arranged at a central distance, which is attached to the free end of a horizontal cantilever arm 24 of a support 25. The support 25 is mounted on a control cabinet 22 in which the control electronics for the laser devices direction 26 is included. A central computer (not shown) with a screen and an input keyboard is connected to the control cabinet 22.

A device shown in FIG. 5, for example, which is currently used for laser marking, can be used as the laser device 26. One example is the laser marking system Stylus, which is shown in the brochure "Laser marking systems" from Quantronix GmbH.

In this laser device 26, the laser beam 28 is generated in a resonator, coupled out at one end and expanded to a multiple of its original diameter, before it successively encounters two computer-controlled mirrors 42, 44 of a beam deflection system (galvo deflection head), which X-ray the laser beam 28 or deflect the Y direction. The beam 29 is focused on the sheet 20 to be processed by means of a plane field optic 28 (FIG. 6) facing the sheet 20, on which it can generate freely programmable fold lines and cuts.

If the arch 20 is larger than the area that can be processed by the laser device 26, the laser device 26 can be arranged displaceably in the longitudinal direction of the cantilever arm 24, as indicated by the double arrow, and / or transversely to the longitudinal direction of the cantilever arm 24 , wherein the displacement of the laser device 26 is computer-controlled.

Alternatively, the possibility can also be created to shift the support of the sheet 20 in the longitudinal and / or transverse direction under computer control by means of a suitable displacement device. If 20 fold lines are to be formed on both surfaces of a sheet, further laser devices can be arranged below the sheet 20 if the sheet 20 is fixed locally so that its lower surface is exposed in the processing area.

The plant shown in FIG. 4 for producing blanks from material sheets has, in the conveying direction indicated by arrow A, a sheet feed table 32, a processing device, a stripping unit 36 and a sheet separating unit 38 in succession. The sheets 30 are conveyed by means of a conveyor, e.g. a conveyor belt, gradually transported in the direction of conveyance. The processing device 34 essentially corresponds to the processing device shown in FIG. 3. It differs in that, in addition to the laser device 26 attached above the sheet 20, a further laser device 26 'is provided below the sheet 20 for processing the underside of the sheet 20. So that the sheet 20 can be processed from below by the laser 26 ', its sheet surface must be accessible from below at the processing points. Appropriate recesses can be provided in the conveyor belt for this purpose.

To produce the blanks from a sheet of material, a sheet of material 20 is placed on the conveyor table 32 on a conveyor belt. A conveyor belt can be used as the conveyor belt which has a vacuum device which opens into openings on the conveyor surface of the conveyor belt, so that a sheet 20 can be fixed on the conveyor belt by negative pressure.

The sheet 20 is then conveyed into the processing unit 34 and processed by means of the laser devices 26, 26 'in accordance with a processing program previously entered into the computer in such a way that the desired cutting and fold lines are provided in the sheet 20. The material of the sheet 20 is cut along the cutting lines.

After processing in the processing device, the sheet is conveyed to the stripping unit 36, at which stripping parts which are located in the cut surface are broken out. Finally, the sheet 20 is conveyed into the depaneling unit 38, in which the individual cuts are removed from the rest of the sheet.

The finished blanks are then fed to an automatic packaging machine (not shown).

If the processing area of the laser devices 26, 26 'is smaller than the sheet surface to be processed, the laser devices 26, 26' can be moved in the transverse and / or longitudinal direction as described with reference to FIG. 3. However, it is also possible to move the conveyor belt step by step so that only a certain number of rows of blanks (FIG. 2) are processed by the laser devices 26, 26 '. After processing, the conveyor belt is started again until there is a further number of rows in the processing area of the laser devices 26, 26 '.

The formation of fold lines by means of a laser beam offers the possibility of designing the fold lines differently as desired. By shifting the laser beam as well as different laser strengths and speeds as well as one or more times along a straight line, a wide variety of cross-sectional shapes can be achieved for the fold lines.

If the material is prone to high smoke formation, the laser beam can form a fold line several times with one predetermined speed and a relatively low dose predetermined thickness along a straight line on the material sheet to remove the material in layers. In this way, not only dust formation but also blackening of the sheet material is prevented.

Example 1 :

The material sheet 50 shown in FIG. 7a consists of coated chromo duplex cardboard (GD2) and is coated on its lower surface 52 with pulp and chalk sanding. The top surface 50 is untreated. Its thickness is 0.40 mm.

To form a cross-sectionally V-shaped fold line 56 with a V-angle α of approx. 90 "and a depth t of 0.15 mm, a laser beam with a strength of 50 W is scanned along a straight line at a speed of 500 mm / s move on the upper surface 54.

Example 2:

The material sheet 60 shown in FIG. 8a consists of coated chromo cardboard (GC2) and is coated on its lower surface 62 with pulp and chalk sanding. The top surface 64 is untreated. Its thickness is 0.63 mm.

In order to form a fold line 66 with a W-shaped cross section, a laser beam with a strength of 80 W is moved on the upper surface along a length of two parallel straight lines, which are spaced 0.4 mm apart, at a speed of 800 mm / s. The two V-shaped grooves 68, 69 formed each have a V angle of 80 ° and a depth of 0.25 mm. Example 3:

The material sheet 70 shown in FIG. 9a consists of coated chromo cardboard (GC2) and is coated on its lower surface 72 with pulp and chalk sanding. The top surface 74 is untreated. Its thickness is 0.63 mm.

To form the three-groove fold line 76, a laser beam with a strength of 40 W is first moved at a speed of 2000 mm / s on the upper surface to form the left groove 77 along a first straight line.

The laser beam is then moved with the same strength and speed to form the right groove 78 along a second straight line which runs parallel to the first straight line and is at a distance of 0.6 mm therefrom.

Finally, the laser beam is moved to form the central groove 79 with a strength of 80 W at a speed of 1500 mm / s on the upper surface along a third straight line, which is at the same distance from the first and second straight lines.

The grooves 77, 78 each have a V angle of 70 ° and a depth of 0.1 mm. The middle groove 79 has a V angle of 80 ° and a depth of 0.2 mm

Example 4:

The material sheet 80 shown in FIG. 10a consists of coated chromo duplex cardboard (GD2) and is coated on its lower surface 82 with pulp and chalk sanding. The top surface 84 is untreated. Its thickness is 0.4 mm. To form the trapezoidal fold line 86, a laser beam with a strength of 50 W is first moved along a first straight line at a speed of 500 mm / s on the upper surface.

The laser beam is then moved with the same strength and speed along a second straight line which runs parallel to the first straight line and is at a distance of 0.3 mm from it.

Finally, the laser beam with a strength of 50 W is moved at a speed of 500 mm / s on the upper surface along a third straight line which is at the same distance of 0.15 mm from the first and second straight lines.

The trapezoidal fold line 86 each has a V-angle α of 50 ° and a depth of 0.15 mm.

If the material sheets to be processed are larger than the processing area of a laser device 26, 26 ', it is also possible to provide further lasers so that the entire area of the sheet can be processed. This reduces the cycle time of the method according to the invention.

With the method according to the invention, it is possible to design the fold lines differently in the case of a cut. The production of the blanks has been described above with the aid of material sheets which consist of cardboard or corrugated cardboard, with individual layers of the material being removed to form fold lines. However, the method according to the invention can also be used to produce packaging from plastics or from composite materials.

The invention is not based on the use of CO ₂ lasers limited. For example, Nd: YAG lasers can also be used. It is also possible to use laser diodes instead of the laser, whose size is smaller and whose installation in the processing device is much easier.

Claims

claims

1. Process for the production of blanks provided with folding lines for folding packaging from a sheet of material, characterized in that the folding lines are formed by contactless removal of material from the sheet of material.

2. Method for the production of blanks provided with folding lines for folding packaging from a sheet of material which has a decorated first surface which faces outwards after the folding packaging has been produced and a second surface which points inwards after the folding packaging has been produced , characterized in that the folding lines are formed by contactless removal of material from the material sheet on the second surface.

3. The method according to claim 1 or 2, characterized in that the fold line formation is carried out by ablation by means of a laser beam.

4. The method according to claim 3, characterized in that the laser beam is moved once to form a fold line at a predetermined speed and a predetermined strength along a straight line on the material sheet.

5. The method according to claim 3, characterized in that the laser beam to form a fold line is moved several times at a predetermined speed and a predetermined thickness along a straight line on the sheet of material.

6. The method according to claim 3, characterized in that the laser beam is formed to form a fold line at a predetermined speed and a predetermined thickness along at least two parallel straight lines on the material sheet.

7. blank produced by a method according to any one of the preceding claims.

8. folding packaging made from a blank according to claim 7.