An improved slotter module for a converting machine for making packaging elements

Abstract

The present invention relates to a slotter module (16) for a converting machine (1) for making packaging elements from sheet formed materials, the slotter module comprising an upper attachment bracket (21) onto which a disc-shaped rotative slotting head (22) arranged on a first shaft (23) is mounted, a lower attachment bracket (21') onto which a disc-shaped rotative slotting anvil assembly (24) arranged on a second shaft (25) is mounted, the first shaft (23) being parallel to the second shaft (25) in a vertical direction, the slotting head (22) being equipped with at least one knife (31), the slotting anvil assembly (24) comprising a groove (32), the slotter module further comprising a scraper (33) linked to the lower attachment bracket (21') such that the scraper at least partially extends inside the groove (32) to eject cutting waste from the groove (32). The invention further pertains to a converting machine (1) for making packaging elements from sheet formed materials, which comprises a such slotter module (16).

Description

[0001] AN IMPROVED SLOTTER MODULE FOR A CONVERTING MACHINE FOR MAKING PACKAGING ELEMENTS

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to the field of converting machines for making packaging elements. The invention relates more specifically to a slotter module for a converting machine for making packaging elements from sheet formed materials. It also pertains to a converting machine comprising a such slotter module.

[0004] BACKGROUND OF THE INVENTION

[0005] Converting machines, for instance flexo folder-gluers, are used to produce packaging elements like folding boxes. These machines comprise a variety of work modules to process sheets of corrugated cardboard or similar material. Among these modules, a slotter module is typically used to cut slots in the sheets. To do so, at least one knife designed to cut slots is fixed on at least one disc-shaped rotative slotting head, which is slidably mounted on a first shaft above and facing vertically at least one disc-shaped rotative slotting anvil assembly, which is slidably mounted on a second shaft to support a sheet being cut.

[0006] When a slot is cut in a sheet with the knife of the slotting head, a cutting waste or debris, i.e. a small rectangular fragment of the sheet, is evacuated into a groove formed between the sheet-contacting elements of the lower slotting anvil assembly, which are commonly called the counter-blades. And to eject this waste out of the groove, a scraper is typically fixed to a lower attachment bracket that supports the slotting anvil assembly in such a way that the scraper at least partially engages in the groove to contact the cutting waste when the slotting anvil assembly rotates. An example of such a scraper arranged in a known slotter module is disclosed in EP 2 452811 B1 . It has a substantially triangular cross-section, with a tip that engages in the groove formed between the counter-blades, and it is positioned so that it rubs against the bottom surface of the groove to ensure proper cutting waste ejection.

[0007] However, the fact that the scraper’s tip is in contact with the bottom surface of the groove causes premature wear, necessitating frequent replacements, and, consequently, greater downtime of the converting machine.

[0008] Moreover, the scraper is fixed at a sole fixation point on the lower attachment bracket that holds the slotting anvil assembly. Experience shows that this design leads to premature wear of the scraper’s lateral surfaces resulting in suboptimal cutting waste ejection.

[0009] Additionally, in some cases, the scraper even moves at an angle in the groove, leading to the slowdown of the slotting anvil assembly and, at worst, the extreme consequence of the blocking of the slotting anvil assembly’s shaft.

[0010] Besides, because the scraper’s tip rubs against the bottom surface of the groove, it causes overheating and even the potential risk of triggering a fire due to the dust present in the module.

[0011] Furthermore, the scraper must sometimes be cleaned of fragments of cardboard that are not ejected and get stuck on the scraper and / or in the groove. With a single fixation point, these cleaning operations can lead to improper reassembly, further increasing the risk of experiencing the above- mentioned inconveniences.

[0012] SUMMARY OF THE INVENTION The present invention aims to remedy these drawbacks. Accordingly, it is an object of the invention to provide a slotter module equipped with scrapers that ensure optimal waste ejection, while minimizing the risk of shaft blocking, preventing premature wear of the scrapers, and avoiding improper cutting waste ejection, potential overheating, and fire.

[0013] In order to achieve this object, a first aspect of the present invention pertains to a slotter module for a converting machine for making packaging elements from sheet formed materials, the slotter module comprising an upper attachment bracket onto which a disc-shaped rotative slotting head arranged on a first shaft is mounted, a lower attachment bracket onto which a disc-shaped rotative slotting anvil assembly arranged on a second shaft is mounted, the first shaft being parallel to the second shaft in a vertical direction. The slotting head is equipped with at least one knife, and the slotting anvil assembly comprises a groove. The slotter module further comprises a scraper linked to the lower attachment bracket such that the scraper at least partially extends inside the groove to eject cutting waste from the groove. Advantageously, the scraper has a hook shape.

[0014] In one embodiment, the scraper is fixed to the lower attachment bracket so that it lies between the knife and the bottom of the groove when a portion of the knife enters the groove. With this configuration, proper ejection of cutting waste is optimized.

[0015] In one embodiment, the scraper is fixed to the lower attachment bracket so that it does not touch the bottom of the groove. This reduces the risk to deteriorate the scraper or the lower slotting anvil assembly’s counterblades.

[0016] In one embodiment, the scraper has a first end and a second end, the length of a line segment joining the first end and the second end being greater than the diameter of the lower slotting anvil assembly. These dimensions of the scraper further optimize the ability to provide proper cutting waste ejection, and they prevent premature wear of the scraper’s lateral surfaces.

[0017] In one embodiment, the cross-section of the first end has a different shape than the cross-section of the second end.

[0018] In one embodiment, the cross-section of the first end has a truncated right triangle shape. This specific shape further optimizes cutting waste ejection efficacy and allows control of cutting waste ejection trajectory.

[0019] In one embodiment, the scraper is fixed to the attachment bracket at two fixation points. That way, premature wear of the scraper is minimized, and so is the risk of cutting waste accumulation that may cause overheating and fire.

[0020] In one embodiment, the fixation points are diametrically opposed with respect to the center of the second shaft. This configuration further enhances the stability of the scraper, thereby preventing from shaft blocking and overheating, and it further improves the ability to provide efficient cutting waste ejection.

[0021] In one embodiment, the scraper is screwed to the attachment bracket. That way, the scraper can be easily removed to facilitate cleaning operations and / or maintenance.

[0022] Another aspect of the present invention pertains to a converting machine for making packaging elements from sheet formed materials, which comprises a slotter module as described above.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the appended drawings, in which like features are denoted with the same reference numbers and in which:

[0024] - Figure 1 is a schematic view of a converting machine according to an embodiment of the invention;

[0025] - Figure 2 is a perspective view of some components of a slotter module according to the invention;

[0026] - Figure 3 is a cross-sectional view of a portion of a slotter module according to the invention; and

[0027] - Figure 4 is a perspective view of a scraper of a slotter module according to the invention.

[0028] DETAILED DESCRIPTION

[0029] A converting machine 1 for making packaging elements from sheet formed materials according to an embodiment of the present invention is illustrated in Figure 1 . In this embodiment, the converting machine 1 takes the form of a flexo folder-gluer (FFG) that is used to produce folding boxes from sheets of corrugated cardboard or other similar paper-based material. It thus comprises a plurality of different work modules to print, cut and crease sheets. The invention, however, is applicable to other types of converting machine which comprise a slotter module equipped with disc-shaped rotative tools.

[0030] From the inlet of the converting machine 1 and in the direction of transportation T of the sheets, which is horizontal and therefore perpendicular to a vertical direction going from the ground to the top of the machine, the converting machine 1 preferably comprises a pre-feeder 12, a feeder module 13, a printing module 14 comprising a plurality of flexographic printing modules 15, a slotter module 16, possibly a rotary diecutter, a folding module 17 and a delivery module 18. Figure 2 illustrates a slotter module according to the prior art. It shares the same main components with the slotter module 16 of the converting machine 1 according to the invention, differing only in its scrapers, as will be explained in detail below.

[0031] Thus, the slotter module 16 of the converting machine 1 according to the invention comprises, above, a plurality of upper attachment brackets 21 , each supporting a disc-shaped rotative slotting head 22, which is slidably mounted on a first shaft 23. Below, it comprises a plurality of lower attachment brackets 2T, each supporting a disc-shaped rotative slotting anvil assembly 24, which is slidably mounted on a second shaft 25 that is parallel to the first shaft 23 in a vertical direction, i.e. a direction which is perpendicular to the direction of transportation of the sheets T. As is apparent to the skilled person, the upper attachment bracket 21 and the lower attachment bracket 2T allow the slotting head 22 and the slotting anvil assembly 24, respectively, to move transversally along their respective shafts in a synchronized manner.

[0032] Figure 3 illustrates a cross-sectional view of the slotter module 16 of the converting machine 1 according to the invention. This view is obtained with a cutting plane perpendicular to the transportation direction T and positioned to cut the upper slotting head 22 and the lower slotting anvil assembly 24 in half. That is, the cutting plane used to obtain the view shown in Figure 3 is oriented and positioned as the one identified A-A in Figure 2.

[0033] Accordingly, the following paragraphs detail the components of the slotter module 16 of the converting machine 1 according to the invention that belong to such a cutting plane. It is understood, however, that the same components are identically reproduced with respect to each pair of attachment brackets, upper and lower, onto which a slotting head and a slotting anvil assembly are mounted to cut slots in sheets that are processed in the converting machine 1. In other words, although the explanations below are given in relation to one slotting head, one slotting anvil assembly, and one scraper, it is understood that the slotter module 16 of the converting machine 1 according to the invention comprises several such elements in an identical configuration.

[0034] Like other known slotter modules for converting machines for making packaging elements from corrugated cardboard sheets, the slotting head 22 of the slotter module of the converting machine 1 according to the invention is equipped with at least one knife 31 , and the slotting anvil assembly 24 comprises two counter-blades facing each other. Between the counterblades, a groove 32 is formed and dimensioned to allow at least a portion of the knife 31 to fit when the upper slotting head 22 rotates, particularly a cutting portion of the knife 31 . Consequently, a cutting waste produced when a slot is cut by the knife 31 in a sheet is evacuated directly into the groove 32. To eject the cutting waste from the groove 32, a scraper 33 is fixed to the lower attachment bracket 2T so that it at least partially extends inside the groove 32.

[0035] Advantageously, the scraper 33 has a hook shape. In other words, its profile roughly resembles a comma. When it is fixed in its working position to the lower attachment bracket 2T, it lies between the knife 31 and the bottom of the groove 32 when the cutting portion of the knife 31 enters the groove 32, as illustrated in Figure 3. That is, compared to known scrapers, the scraper 33 has a shape that allows it to extend around the slotting anvil assembly 24 over a relatively long length.

[0036] This design advantageously optimizes the ability to properly eject cutting waste from the groove 32 because of both the scraper’s 33 shape and its positioning that prevent cutting waste from ever reaching the bottom of the groove 32. Additionally, the scraper 33 is fixed to the lower attachment bracket 2T so that it does not touch the bottom of the groove 32. Consequently, premature wear of the scrapper 33 is minimized, and the risk of overheating and fire is avoided.

[0037] Moreover, the scraper 33 is fixed to the lower attachment bracket 21 ’ at two fixation points 34, 35, preferably with screws or bolts.

[0038] In a preferred embodiment, the fixation points are diametrically opposed with respect to the center of the second shaft 25, as illustrated in Figure 3. Consequently, the risk of the scraper 33 becoming loose and moving at an angle inside the groove 32 is minimized. This configuration also reduces the risk of improper reassembly when cleaning operations are performed. As a result, premature wear of the scraper 33 is significantly minimized.

[0039] Figure 4 shows a front view of a scraper 33 arranged in a slotter module 16 according to the invention. It is advantageously formed so that the length of a line segment joining its first end 41 and its second end 42 is greater than the diameter of the lower slotting anvil assembly 24. This aspect is apparent on Figure 3.

[0040] Moreover, the first end’s 41 cross-section has a different shape than the second end’s 42 cross-section. Advantageously, the first end’s 41 crosssection has a truncated right triangle shape. This specific shape in combination with the way the scraper 33 is fixed to the lower attachment bracket 2T between the counter-blades of the slotting anvil assembly 24 ensures that cutting waste is properly ejected from the groove 32 when the slotting anvil assembly 24 rotates. Indeed, cutting waste is eventually forced to exit the groove 32 due to the scraper’s edge, which significantly protrudes from the groove 32. Moreover, this shape also allows better control of cutting waste ejection trajectory. Indeed, the design of the scraper’s first end 41 , particularly the way the first end 41 gradually widens, can advantageously be adjusted according to the way cutting waste is collected in the slotter module.

Claims

CLAIMS1. A slotter module (16) for a converting machine (1 ) for making packaging elements from sheet formed materials, the slotter module comprising an upper attachment bracket (21 ) onto which a discshaped rotative slotting head (22) arranged on a first shaft (23) is mounted, a lower attachment bracket (21’) onto which a disc-shaped rotative slotting anvil assembly (24) arranged on a second shaft (25) is mounted, the first shaft (23) being parallel to the second shaft (25) in a vertical direction, the slotting head (22) being equipped with at least one knife (31 ), the slotting anvil assembly (24) comprising a groove (32), the slotter module further comprising a scraper (33) linked to the lower attachment bracket (21’) such that the scraper at least partially extends inside the groove (32) to eject cutting waste from the groove (32), wherein the scraper has a hook shape.

2. The slotter module (16) according to claim 1 , wherein the scraper (33) is fixed to the lower attachment bracket (2T) so that it lies between the knife (31 ) and the bottom of the groove (32) when a portion of the knife enters the groove.

3. The slotter module (16) according to any one of the preceding claims, wherein the scraper (33) is fixed to the lower attachment bracket (2T) so that it does not touch the bottom of the groove (32).

4. The slotter module (16) according to any one of the preceding claims, wherein the scraper (33) has a first end (41 ) and a second end (42), the length of a line segment joining the first end and the second end being greater than the diameter of the slotting anvil assembly (24).

5. The slotter module (16) according to claim 4, wherein the cross-section of the first end (41 ) has a different shape than the cross-section of the second end (42).

6. The slotter module (16) according to one of claims 4-5, wherein the cross-section of the first end (41 ) has a truncated right triangle shape.

7. The slotter module (16) according to any one of the preceding claims, wherein the scraper (33) is fixed to the lower attachment bracket (2T) at two fixation points (34, 35).

8. The slotter module (16) according to claim 7, wherein the fixation points (34, 35) are diametrically opposed with respect to the center of the second shaft (25).

9. The slotter module (16) according to any one of the preceding claims, wherein the scraper (33) is screwed to the lower attachment bracket (2T).

10. A converting machine (1 ) for making packaging elements from sheet formed materials, wherein it comprises a slotter module (16) according to any one of the preceding claims.

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