Punching tool

Abstract

In a die-cutting tool for cutting plastic-based film elements (12), comprising a die-cutting unit (13) having several knife carriers, each with at least one die-cutting knife (18) having a cutting wedge (28) tapering towards a cutting edge (29), and a die (14) assigned to the die-cutting unit (13) and opposite it for receiving the film element (12) to be processed, wherein the die-cutting unit (13) is mounted to be relatively movable relative to the die (14) during a die-cutting stroke in a stroke direction (15) between a starting position and a processing position, wherein the cutting wedges (28) of the die-cutting knives (18) plunge into the film element (12) to be processed in the processing position and, depending on their penetration depth, produce a cutting line or break line in the film element (12) along an edge length of the cutting edge (29),The cutting edge (29) has a perforation section (32) for generating a break line and on both sides of the perforation section (32) a cutting section (33) for generating a cutting line, wherein the cutting sections (33) project in the stroke direction (15) relative to the perforation section (32).

Description

[0001] Punching tool for cutting plastic-based film elements, with a punching unit which has a plurality of knife carriers, to each of which at least one punching knife is fastened, each having a cutting wedge tapering towards a cutting edge, and with a die assigned to the punching unit and opposite it for receiving the film element to be processed, wherein the punching unit is mounted so as to be relatively movable relative to the die during a punching stroke taking place in a stroke direction between a starting position and a processing position, wherein the cutting wedges of the punching knives immerse themselves in the film element to be processed in the processing position and, depending on their immersion depth, produce a cutting line or breaking line in the film element along an edge length of the cutting edge.

[0002] Such punching tools have been known for a long time. Their purpose is to cut / perforate large-area plastic film elements, which can be, for example, a two-dimensional large-area film or a three-dimensional film element. Such three-dimensional film elements can be, for example, yogurt cups, which need to be processed in a specific way after production, for example by being separated or cut out in specific groups, for example in groups of four, six, or eight. Important components of such punching tools are punching knives, which, depending on the depth of penetration into the film element, create either a cutting line or alternatively a breaking line. If a cutting line is created, the film element is cut completely. If a breaking line is created, the film element to be processed is weakened along this line.

[0003] Useful break lines or predetermined breaking lines are characterized by small, weakened material bridges that alternate with completely cut areas. However, when creating such break lines or predetermined breaking lines, it can happen that unweakened material bridges remain at the transition between the punching blade and another component of the punching unit, such as a contour punch, for example, if the punching blade cannot penetrate deep enough into the die. This can then lead to adjacent cavities, such as yogurt cups, becoming stuck to one another at these points when they are bent. EP-A-3885085 discloses a punching tool according to the preamble of claim 1.

[0004] The object of the invention is therefore to create a punching tool of the type mentioned at the outset, in which the processing of plastic-based film elements, in particular those made of thermoplastic, is more reliable than with conventional punching tools.

[0005] This object is achieved by a punching tool having the features of independent claim 1. Further developments of the invention are presented in the subclaims.

[0006] The punching tool according to the invention is characterized in that the cutting edge has a perforation section for producing a breaking line or predetermined breaking line and on both sides of the perforation section a cutting section for producing a cutting line, wherein the cutting sections protrude in the stroke direction relative to the perforation section.

[0007] During the punching stroke, the cutting sections of the cutting edge first penetrate the film element to be processed before the perforation section comes into contact with the film element. This ensures that the edge areas, particularly at the transition between the punching blade and another component of the punching unit, such as a contour punch, are completely cut, thus preventing unweakened material bridges. The trailing or downstream perforation section of the cutting edge then creates a break line or predetermined breaking line as it moves further into the die. This ensures that connected cavities, such as yogurt cups, can be completely separated from one another quickly and easily when bent along the predetermined breaking line or breaking line.This ensures product optimization in downstream processes, especially in the downstream singulation process, which is carried out by the user (end customer).

[0008] The punching tool according to the invention is thus characterized by at least one punching knife with a stepped cutting edge.

[0009] In a further development of the invention, the perforation section and the cutting sections are aligned with each other in such a way that the breaking line or predetermined breaking line produced by the perforation section and the cutting lines produced to the left and right of the breaking line by means of the cutting sections lie on one line.

[0010] In a particularly preferred manner, the cutting edge has a perforation edge section assigned to the perforation section and a cutting section edge section assigned to the cutting sections.

[0011] Particularly preferably, the perforation edge section and the cutting section edge section of the cutting edge are aligned with each other when viewed from below. This ensures that the break line or predetermined breaking line and the cutting lines adjacent to it on the left and right are aligned.

[0012] Particularly preferably, the cutting sections are tooth-shaped. The cutting sections could therefore also be referred to as cutting teeth.

[0013] In a further development of the invention, the cutting wedge has a wedge surface oriented obliquely to the stroke direction, and the cutting sections are raised relative to the wedge surface. Thus, the cutting sections preferably protrude not only in the stroke direction relative to the perforation section, but also at an angle to the stroke direction relative to the wedge surface.

[0014] In a further development of the invention, the perforation section has several cutting areas along the perforation edge section for creating cutting lines and several perforation areas set back from the cutting areas for creating material weakenings in the film element to be processed. The combination of the cutting lines and the material weakenings along the perforation edge section of the cutting edge then creates the break line or predetermined breaking line.

[0015] Particularly preferably, the cutting areas and the perforation areas are arranged alternately. Advantageously, the cutting areas all have the same length. Preferably, the perforation areas also all have the same length.

[0016] However, the cutting areas are particularly preferably longer, in particular significantly longer than the perforation areas.

[0017] Particularly preferably, the perforation areas are formed by recesses aligned in the stroke direction and open toward the cutting edge. The cutting edge is recessed in the area of ​​these recesses, so that when the perforation section penetrates the film element, the cutting areas create cutting lines, while the perforation areas with the recessed cutting edge merely form a material weakening in the film element.

[0018] In a further development of the invention, the punching unit has contour punches adjacent to the punching blades, with the cutting sections located on the cutting edge of the punching blade at the transition from the punching blade to the contour punch. Critical areas are particularly present here, which, in "normal" punching blades without leading cutting sections, ensure non-weakened areas where adjacent cavities can get caught when bending along the break line.

[0019] The invention further comprises a method for cutting plastic-based film elements using a punching tool according to one of the preceding claims, the method comprising the following steps: Inserting the film element to be processed into the die, relative movement of the punching unit and die to each other, penetration of the cutting section edge parts of the cutting sections of the cutting edge into the film element to be processed to create a cutting line in the film element, further movement of the punching unit and penetration of the perforation edge part of the perforation section of the cutting edge into the film element to be processed to create cutting lines through the cutting areas and material weakenings through the perforation areas in the film element.

[0020] A preferred embodiment of the invention is illustrated in the drawing and explained in more detail below. The drawing shows: Figure 1 is a perspective view of a preferred embodiment of the punching tool according to the invention, equipped with punching blades not belonging to the invention, Figure 2 is a perspective view of a preferred embodiment of a punching blade of the punching tool according to the invention out of contact with the film element to be processed, and Figure 3 is a perspective view of the punching blade of Figure 2 when the cutting sections of the cutting edge penetrate into the film element to be machined, whereby the film element is not shown.

[0021] The Figures 1 to 3show a preferred embodiment of the punching tool 11 according to the invention for cutting / perforating plastic-based film elements 12. The punching tool according to the invention is described below using a three-dimensional PET-based film element 12 as an example, which can be, for example, a yogurt cup. It is of course also possible to use the punching tool 11 according to the invention to cut, perforate, and process completely different plastic-based film elements 12, for example, two-dimensional plastic films. Furthermore, it is possible to use the punching tool 11 according to the invention to process plastic-based film elements 12 that consist of a base film, for example of a mono-material, for example mono-PET, mono-PP, and an overlying sealing film.

[0022] The aim of the punching processing of the plastic / in particular PET-based film elements 12 is to assemble the film elements 12 from a virtually endless raw strand into individual groups or individual elements.

[0023] As particularly in Figure 1 As shown, the punching tool 11 has a punching unit 13, which forms the movable part of the punching tool 11. A die 14 for receiving the film element 12 to be processed is arranged opposite the punching unit 13, wherein the punching unit 13 is mounted so as to be relatively movable relative to the die 14 during a punching stroke taking place in a stroke direction 15 between a starting position and a processing position.

[0024] As further stated in Figure 1As shown, the punching unit 13 has a base plate 16, which is illustrated as a rectangular shape. Several functional components of the punching unit 13 are attached to the base plate 16.

[0025] The functional components include several punching knife modules 17, each having at least one punching knife 18 mounted on a knife carrier, for example, in a height-adjustable manner, wherein the knife carrier is connected to the base plate 16 via a base body 19. The punching knives 18 are each releasably attached to an associated knife seat (not shown) of the knife carrier by means of fastening means.

[0026] The functionality and structure, or rather the geometry and contour, of the punching blades 18 are explained below using a single punching blade 18. Of course, the other punching blades 18 of the punching unit 13, or at least one group of punching blades 18 of the punching unit 13, are also designed in the same way.

[0027] As fastening means, for example, fastening screws 20 ( Figure 1 ) is used, the associated through holes 21 ( Figure 1 ) in the punching knife 18 and are countersunk into corresponding recesses (not shown) in a bearing section of the knife carrier. The fastening screws and through holes 20, 21 are in the Figures 2 and 3 shown embodiment of the punching knife 18 is not shown.

[0028] A tuning element (not shown) in the form of a relatively thin tuning disk can be arranged between the seat surface of the knife seat and the punching knife 18.

[0029] Of particular interest are the geometry and contour of the punching knife 18, which are described in more detail below: As particularly shown in the Figures 2 and 3 As shown, the punching knife 18 has a bearing or clamping section 22, which is penetrated transversely to the stroke direction by the two through holes (not shown).

[0030] As particularly in the Figures 2 and 3 As shown, the clamping section has a front side 23 and a rear side 24 arranged opposite the front side 23. The front side 23 and rear side 24 of the clamping section 22 extend in the width direction 25 of the punching blade 18 and are preferably aligned parallel to each other. The front side 23 is connected to the rear side 24 by a flank section 26. The flank section extends in the depth direction 27 of the punching blade 18. As further shown in Figure 2 and 3As shown, the two flank sections 26 converge from the rear side to the front side 23.

[0031] Adjacent to the clamping section 22 along the stroke direction 15, which can also be referred to as the height direction, is a cutting wedge 28 that tapers towards a cutting edge 29. The cutting wedge 28 has a first wedge surface 30 facing the die 14 and a second wedge surface 31 oriented obliquely to the first wedge surface 30, facing away from the die 14 and oriented obliquely to the stroke direction 15. The first wedge surface 30 and the rear side 24 of the clamping section 22 are aligned with one another and merge into one another.

[0032] As the overview of the Figures 2 and 3As shown, the cutting edge 29 has a perforation section 32 for creating a breaking line or predetermined breaking line, and a cutting section 33 on each side of the perforation section 32 for creating a cutting line. The cutting sections 33 protrude relative to the perforation section 32 in the stroke direction 15.

[0033] The perforation section 32 has a perforation edge section 34 at its lower end, which is part of the cutting edge 29, i.e., the edge line of the cutting edge 29. When immersed in the film element 12 to be processed, the perforation edge section 24 creates a breaking line or predetermined breaking line. The perforation section 32 has several cutting areas 35 along the perforation edge section 34 for creating cutting lines and several perforation areas 36 set back from the cutting areas 35 for creating material weakenings in the film element 12 to be processed. The cutting areas 35 have a straight course and are aligned perpendicular to the stroke direction 15.The cutting areas 35 have a particularly significantly greater extent than the perforation areas 36, for example the cutting areas 35 extend over several millimeters, while the perforation areas 36 are particularly well under one millimeter long.

[0034] As further stated in the Figures 2 and 3As shown, the cutting areas 35 and the perforation areas 36 of the perforation section 32 are arranged alternately. This means that one cutting area 35 is flanked by two perforation areas 36. The cutting areas 35 are expediently of equal length to one another. The perforation areas 36 are also expediently of equal length to one another. In the exemplary embodiment shown, the perforation areas 36 are formed by open recesses 37 aligned in the stroke direction with the cutting edge 29, wherein the cutting edge 29 is set back from the cutting areas 35 in the area of ​​the recesses 37. During a punching stroke, the cutting areas 35 therefore create a cutting line, while the perforation areas 36 only partially penetrate into the film element 12 to be processed and weaken the material there, but do not completely cut through it.

[0035] An essential element of the invention are the aforementioned cutting sections 33, which precede the perforation section 32 in the stroke direction 15. This means that during the punching stroke of the punching knife 18, the cutting sections 33 first penetrate into the film element to be processed, before the perforation section 36 even comes into contact with the film element 12 to be processed.

[0036] The perforation section 32 and the cutting sections 33 are aligned with each other in such a way that the breaking line or predetermined breaking line produced by the perforation section 32 and the cutting lines produced to the left and right of the breaking line by means of the cutting sections 33 lie on one line.

[0037] For this purpose, the cutting sections have cutting section edge sections 38 at their free end, which are aligned with the perforation edge section 34 when viewed from below.

[0038] The cutting sections 33 are tooth-like. The cutting sections 33 could therefore also be referred to as incisors.

[0039] As further stated in Figure 2 or 3 As shown, the cutting sections 33 protrude both in the stroke direction 15 or height direction from the perforation section 32 and in the depth direction 27, i.e., the cutting sections 33 are raised relative to the second wedge surface 31 of the cutting wedge 28. The cutting sections 33 each have cutting section outer surfaces 39 that are aligned parallel to the first wedge surface 30.

[0040] As further stated in the Figures 2 and 3 As shown, the punching unit 13 has contour punches 40 adjacent to the punching knives 18, wherein the cutting sections 33 are located on the cutting edge 29 of the punching knife 18 at the transition from the punching knife 18 to the contour punch 40.

[0041] The method according to the invention for cutting or perforating plastic-based film elements 12 using the punching tool 11 according to the invention proceeds according to the following steps: Initially, the punching unit 13 is in the raised starting position. Depending on the processing task, groups of punching blades are then arranged so that, for example, a group of four, such as four-cup yogurt cups, or other groups can be cut from the film element 12 to be processed. At the same time, predetermined breaking lines or break lines are introduced within the group in the manner described below.

[0042] The foil element 12 to be processed is inserted into the die 14. As shown in particular in the Figures 2 and 3 As shown, the die 14 has a die cavity 41 into which the punching knife 18 can move during the cutting or perforation process.

[0043] After inserting the foil element 12 to be processed, the punching unit 13 and the die 14 are moved relative to each other, for example by moving the punching unit 13 downwards towards the die 14.

[0044] In this case, the two cutting sections 33 of the cutting edge 29 of the punching knife first come into contact with the film element 12 to be processed and create a cutting line there, ie the two cutting sections or cutting teeth ensure a complete severance of the film element 12 or the base film at these points.

[0045] The perforation section 32 of the cutting edge 29 is not yet in contact with the film element 12 to be processed. After the cutting sections have created the cutting lines, the punching knives plunge further into the die cavity 41 so that the perforation section 32 comes into contact with the film element 12 to be processed. The perforation edge section 34, with its cutting areas 35 and perforation areas 36, creates a breaking line or predetermined breaking line, i.e. cutting lines are created in the area of ​​the cutting areas 35, while the perforation areas 36 merely weaken the material in these areas. After the punching process, a prefabricated group of, in particular, three-dimensional film elements 12, for example, yoghurt cups, is created. The film elements 12 then still hang along the breaking lines orThe predetermined breaking lines are connected to one another because the perforation areas 36 were not completely cut. If the three-dimensional film elements 12 within the group are to be separated from one another, they must be bent along the breaking line. Because the cutting sections 33 to the left and right of the breaking line have already created cutting lines, i.e., complete perforations, it is possible to easily and reliably separate the connected three-dimensional film elements 12 from one another without any remaining material bridges interfering with the separation process.

Claims

1. Punching tool for cutting plastics-based film elements (12), having a punching stamp unit (13) that has multiple blade holders, to each of which at least one punching blade (18) having a cutting wedge (28) that tapers towards a cutting edge (29) is attached, and having a die (14) associated with the punching stamp unit (13), and positioned opposite it, for receiving the film element (12) to be processed, wherein the punching stamp unit (13) is mounted to be movable relative to the die (14) between a starting position and a processing position during a punching stroke occurring in a stroke direction (15), wherein the cutting wedges (28) of the punching blades (18) penetrate the film element (12) in the processing position and, depending on the depth of penetration thereof, produce a cutting line or break line along an edge length of the cutting edge (29) in the film element (12), characterized in that the cutting edge (29) has a perforation section (32) for creating a break line and, on either side of the perforation section (32), cutting sections (33) for creating a cutting line, wherein the cutting sections (33) project in the stroke direction (15) relative to the perforation section (32).

2. Punching tool according to Claim 1, characterized in that the perforation section (32) and the cutting sections (33) are aligned with one another in such a way that the break line created by the perforation section (32) and the cutting lines created to the left and right of the break line by means of the cutting sections (33) lie along one line.

3. Punching tool according to Claim 1 or 2, characterized in that the cutting edge (29) has a perforation-edge portion (34) assigned to the perforation section (32) and a cutting-section edge portion (38) assigned to the cutting sections (33).

4. Punching tool according to Claim 3, characterized in that the perforation-edge portion (34) and the cutting-section edge portion (38) of the cutting edge (29) are aligned with one another in a flush manner in a view from below of the cutting edge (29).

5. Punching tool according to any one of the preceding claims, characterized in that the cutting sections (33) are formed in a tooth-like manner.

6. Punching tool according to any one of the preceding claims, characterized in that the cutting wedge (28) has a wedge surface (31) oriented obliquely to the stroke direction (15) and the cutting sections (33) are formed raised relative to the wedge surface (31).

7. Punching tool according to Claim 6, characterized in that the cutting sections (33) each have cutting-section outer surfaces (39) that are aligned parallel to the wedge surface (31).

8. Punching tool according to any one of Claims 3 to 7, characterized in that the perforation section (32) has multiple cutting areas (35) along the perforation-edge portion (34) for creating cutting lines and multiple perforation areas recessed relative to the cutting areas (35) for creating material weaknesses in the film element (12) to be processed.

9. Punching tool according to Claim 8, characterized in that the cutting areas (35) and the perforation areas (36) are arranged in an alternating manner.

10. Punching tool according to Claim 8 or 9, characterized in that the cutting areas (35) are longer, particularly substantially longer, than the perforation areas (36).

11. Punching tool according to any one of Claims 8 to 10, characterized in that the perforation areas (36) are formed by recesses (37) that are open towards the cutting edge (28) and oriented in the stroke direction (15).

12. Punching tool according to any one of the preceding claims, characterized in that the punching unit (13) has contour punches (40) adjacent to each of the punching blades (18) and the cutting sections (33) are located on the cutting edge (29) of the punching blade (18) at the transition of the punching blade (18) to the contour punch (40).

13. Method for cutting plastics-based film elements (12) using a punching tool (11) according to any one of the preceding claims, the method comprising the following steps: - inserting the film element (12) to be processed into the die (14), - relative movement of the punching unit (13) and the die (14) in respect of one another, - penetration of the cutting-section edge portions (38) of the cutting sections (33) of the cutting edge (29) into the film element (12) to be processed to create a cutting line in the film element (12), - further movement of the punching unit (13) and penetration of the perforation-edge portion (34) of the perforation section (32) of the cutting edge (29) into the film element (12) to be processed to create cutting lines through the cutting areas (35) and material weaknesses through the perforation areas (36) in the film element (12).

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