Feeder module for a converting machine

Abstract

The present invention relates to a feeder module (12) for a converting machine (1) which is configured to only allow the lowermost positioned sheet in the stack to be conveyed under the front stopper at a time. The feeder module comprises a suction bar (28) configured to apply suction against the lower side of the sheet and direct the sheet under the front stopper, and wherein the suction bar comprises a first group of air openings (36) configured to apply suction against the sheet and a second group of air openings (40) configured to blow air against the sheet.

Description

[0001] FEEDER MODULE FOR A CONVERTING MACHINE

[0002] Field of the invention

[0003] The present invention relates to a feeder module for a converting machine. In particular, it relates to a feeder module suitable for feeding sheets one by one into a converting machine.

[0004] Background

[0005] Converting machines such as folder-gluers and rotary die cutters are used in the production of paperboard and cardboard boxes. These machines are configured to produce packaging elements such as flat-packed and folding boxes from sheets.

[0006] These converting machines comprise a plurality of different work modules which may print, cut and crease, and sometimes glue and fold the sheets such that a box or a packaging element is produced.

[0007] Commonly for these converting machines is that they comprise a feeder module which is designed to receive a stack of sheets on a loading surface and to feed the sheets one by one into the converting machine.

[0008] Sometimes pre-printed sheets are placed in the feeder and are further processed in the converting machine by cutting, creasing and sometimes gluing and folding. The pre-printed sheets are often conveyed with the printed side facing downwards.

[0009] The feeder module is provided with a gauge and a small clearance to allow only one sheet to be discharged at a time. Additionally, the feeder module comprises drive belts or rollers configured to push the sheet forward by friction. The restriction at the gauge and the drive rollers often causes rubbing and damages to the lower side of the sheet which is in contact with the drive belts or rollers. Especially if the lower side of the sheet is pre-printed when placed in the feeder module, the printed motif on the sheet can be damaged.

[0010] Summary

[0011] In view of the prior art, it is an object of the present invention to provide an improved feeder module in which deformation marks are prevented. This object is solved by a feeder module according to claim 1 .

[0012] According to a first aspect of the present invention, there is provided a feeder module for a converting machine, the feeder module comprising: a loading surface configured to receive a stack of sheets, a front stopper configured to abut against the front edge of the stack and only allow the lowermost positioned sheet in the stack to be conveyed under the front stopper at a time, drive elements configured to move the lowermost positioned sheet in the stack under the front stopper and forward in a direction of transportation, and wherein the feeder module comprises a suction bar configured to apply suction against the lower side of the lowermost positioned sheet and direct the lowermost sheet under the front stopper, and wherein the suction bar comprises a first group of air openings configured to apply suction against the lowermost sheet and a second group of air openings configured to blow air against the lowermost sheet, and wherein the first group of air openings comprises a plurality of suction openings and the second group of air openings comprises a plurality of air blowing openings.

[0013] This aspect is based on a realization that an air cushion and a suction force can be created at the same time. The interaction between the suction force and the air cushion positions the sheet at a distance from the suction bar or at least reduces the friction between the sheet and the suction bar.

[0014] In an embodiment, the first group of air openings and the second group of air openings are arranged in a lateral direction which is perpendicular to the direction of transportation.

[0015] Preferably, the first group of air openings and the second group of air openings are arranged in the same line and in an alternating manner such that a suction opening from the first group of air openings is located in-between two air blowing openings from the second group of air openings.

[0016] In an embodiment, the airflow rate through a suction opening is larger than the airflow rate through an air blowing opening.

[0017] The first group of air openings may be provided with a funnel-shaped inlet.

[0018] In an embodiment, the second group of air openings have an oval orifice. In an embodiment, an absolute value of the air depression pressure at the orifice of a suction opening is lower than an absolute value of the positive pressure at the orifice of an air blowing opening.

[0019] In an embodiment, an air depression pressure in an air duct connected to the orifice of a suction air opening is between 3000 Pa and 5000 Pa, preferably about 4000 Pa, and wherein a positive pressure is present in an air supply duct connected to an air blowing opening and is between 200000 and 500000 Pa, preferably around 400000 Pa. This allows the formation of an air cushion with a maximum heigh which is lower than a clearance between the front stopper and the suction bar.

[0020] In an embodiment, the suction bar comprises an air conduit and a plurality of therefrom extending inclined channels, and wherein the inclined channels have an outlet which is formed by the orifices of the air blowing openings.

[0021] The first group of air openings may be connected to a suction box which is also in fluidic communication with air openings around drive elements in the loading surface.

[0022] Brief description of the drawings

[0023] 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 in the configuration of a flexo-folder gluer;

[0025] Figure 2a is schematic top view of a printed sheet;

[0026] Figure 2b is schematic top view of a cut-to-shaped blank;

[0027] Figure 2c is a schematic perspective view of a folding box;

[0028] Figure 2d is a schematic perspective view of box assembled from the folding box in figure 2c;

[0029] Figure 3 is a partial schematic perspective view of a feeder module according to an embodiment of the present invention;

[0030] Figure 4a is a detailed perspective view of a suction bar according to an embodiment of the present invention; and Figures 4b and 4c are schematic cross-sectional views showing the profile of the suction bar in a respective first cut A-A and second cut B-B according to an embodiment of the present invention.

[0031] Detailed description

[0032] The present invention can be used in converting machines like for instance printing press machines, rotary die-cutter machines and folder-gluers, such as flexo-folder- gluers. In order to simplify the present description, reference is made to a flexo- folder-gluer machine.

[0033] Referring to the figures, and in particular figures 2a and 2b which show examples of a sheet 2, and a blank 2’ made from cardboard and which is used for manufacturing a folding box 2”, such as the one shown in figure 2c. The folding box 2” can subsequently be assembled into a three-dimension box 2”’ as illustrated in figure 2d. The sheet 2 may already be provided with a motif 5 as it is placed in a feeder module 12 of the converting machine (figure 1). Alternatively, the sheet 2 may be printed in the converting machine 1.

[0034] When a folding box 2” or a flat-packed box is manufactured, a sheet 2 made from paper, cardboard, plastics or like is loaded into the converting machine 1. The sheet 2 is transformed into a blank 2’ by processing it in a plurality of workstations. These workstations transform the sheet 2 by printing, creasing and cutting. Some types of converting machines 1 such as folder-gluers 1 , also comprise gluing and folding modules such as to produce folding boxes and other similar packaging containers.

[0035] A converting machine 1 in the form of a flexo-folder gluer 1 is schematically illustrated in figure 1. The converting machine 1 may comprise successively in a direction of transportation T: a loader 10 for automatically loading a plurality of sheets, a feeder 12, a printing module comprising a plurality of flexography printing units 14, a converting module 16 comprising a slotter unit and at least one cutting unit 18, and a folding-gluing module 20. The converting machine 1 may also further comprise optional modules such as a counting-ejecting module, a bundler and a palletizer (not illustrated).

[0036] The converting machine 1 comprises a conveying system C which is configured to transport the sheet 2 in the direction of transportation T. The conveying system C may include drive rollers and conveyor belts (not illustrated). It is common to use vacuum transfers in and between different work modules where the sheet 2 is transported on its upper surface. The side of conveyance may change in the printing units if there are different printing units configured to respectively print on the top and bottom sides of the sheet 2.

[0037] As illustrated in figure 3, the feeder module 12 comprises a loading surface 24, a front stopper 26 and an elongated suction bar 28. The feeder module 12 is configured to receive a stack of sheets 2 on the loading surface 24 and to discharge the sheets 2 one by one into the conveyance system C of the converting machine 1.

[0038] The feeder module 12 comprises a plurality of drive elements 30 and a movable support surface 32. The drive elements 30 may be drive rollers or belts. The stack of sheets 2 is moved vertically up and down by the movable support surface 32. The movable support surface 32 comprises a plurality of bars 33. The bars 33 are arranged in-between the drive elements 30. The support surface 32 is thus configured to move between a contact position and a clearance position. In the clearance position, the lowermost arranged sheet 2 is in contact with the support surface 32 and located vertically above the drive elements 30. In this position, the lowermost arranged sheet 2 is not in contact with the drive elements 30.

[0039] In the contact position, the support surface 32 is located vertically below the drive elements 30, whereby the lowermost arranged sheet 2 is contacted by the drive elements 30 and driven forward in the direction of transportation T. This up and down movement of the movable support surface 32 ensures that only one sheet 2 is grasped and conveyed at a time.

[0040] The front stopper 26 may be in the form of a stop plate and is arranged downstream of the drive elements 30 in the direction of transportation T. The front stopper has a distal end 29 arranged such that a clearance C1 is formed in-between the suction bar 28 and the front stopper 26. The clearance C1 is selected such as to correspond to the thickness of one sheet substrate 2, or at least be inferior to the combined thickness of two sheet substrates 2. The front stopper 26 ensures that only one sheet 2 is conveyed through the clearance C1 and into the converting machine 1 at a time. The front stopper 26 may comprise a first stop plate 27a and a second stop plate 27b arranged side by side in a lateral direction L, which is perpendicular to the direction of transportation T.

[0041] To ensure that the sheet 2 is directed underneath the front stopper 26, the elongated suction bar 28 is located vertically below the front stopper 26. The suction bar 28 comprises a first group of air openings 36 configured as a plurality of suction openings 36’. The first group of air openings 36 are configured to apply suction against the lower side of the sheet 2 such that the sheet 2 is directed under the front stopper 26. The suction openings 36’ are arranged in a line which is extending in the lateral direction L which is perpendicular to the direction of transportation T.

[0042] As illustrated in figures 4a and 4b, the suction openings 36’ may be provided with a funnel-shaped inlet. The funnel-shape is designed to apply the suction force on a larger area of the sheet than if the suction openings 36’ were straight.

[0043] The suction bar 28 further comprises a second group of air openings 40 comprising a plurality of air outlet openings 40’. The air outlet openings 40’ (also referred to as air blowing openings) are configured to blow air against the lower side of the sheet 2.

[0044] The second group of air openings 40 may have oval orifices. The orifices may be positioned such that they have a longer extension in the direction of transportation T than the lateral direction L. The oval shape allows an inclined air channel 41 having a circular cross section in a direction perpendicular to the longitudinal extension of the air channel 41 .

[0045] Preferably, the suction openings 36’ and the air outlet openings 40’ are arranged in the same line. The line is arranged vertically below the front stopper 26, at an upstream distance of between 5 and 15 mm, preferably about 10 mm. The distance is selected such that the leading edge of the sheet 2 is grasped before the leading edge 3 of the sheet 2 passes under the front stopper 26.

[0046] A suction airflow through each suction opening 36’ can be between 30 and 47 liters / minute, preferably around 40 liters / minute. In an air duct 51 connected to the group suction air openings 36, a depression pressure P1 of between 3000 Pa and 5000 Pa, preferably about 4000 Pa is present. An air blowing airflow Q2 through each air blowing opening 40’ is preferably between 24 and 32 liters per minute, preferably around 25 liters / minute. A positive pressure P2 is present in an air supply duct 50 connected to the group of air outlet openings 40 and is between 200000 Pa and 500000 Pa, preferably around 400000 Pa.

[0047] There may be about a total of 64 suction openings 36’ and about a total of 63 air blowing openings 40’.

[0048] The low airflow rate Q2 through the air outlet openings 40’ is thus smaller than the airflow rate Q1 through the suction openings 36.

[0049] However, the absolute value of the pressure P2 in the air supply duct 50 connected to the orifices of the air outlet openings 40’ is equal or higher than the absolute value of the pressure P1 at the orifice of the suction openings 36’. This allows a formation of an air cushion with a restricted distance of between 1 or 2 mm from the suction bar 28.

[0050] The diameter of a suction opening 36’ may be about 6 mm and diameter of a second air opening 40’ may be about 1.5mm.

[0051] The air blowing openings 40’ are thus configured to apply a strong blowing force only at a small distance from the suction bar 28. This results in that the air cushion is only present close to the suction bar 28, such as from a distance limit of about 1 mm from the air blowing openings 40’. This avoids the sheet 2 from touching the front stopper 26.

[0052] The distance between a suction opening 36’ and an adjacent air blowing opening 40’ is selected such that distinct zones in the lateral direction L are formed where the sheet 2 is in an alternating way sucked against and blown away from the suction bar 28. The distance between the suction openings 36’ can be between 20 mm and 40 mm, preferably about 30 mm. This distance also provides a sufficient distribution of the suction force for small format of sheets 2. An air blowing opening 40’ is positioned in the middle between two suction openings 36’. Hence, the first and second air openings 36’, 40’ are arranged in an alternating sequence such that one in every two air openings is an air blowing opening 40’. The suction bar 28 can be made from a metal. For instance, the suction bar 28 can be manufactured in an additive manufacturing process. As best seen in figures 4b and 4c, the upper surface of the suction bar 28 can be provided with an upstream portion 46 and a downstream portion 48. The downstream portion 48 is located at a vertically lower position than the upstream portion 46. The suction bar 28 is mounted in the feeder module 12 such that a transition point 47 between the upstream portion 46 and the downstream portion 48 is located vertically below the front stopper 26. This recessed downstream portion 48 prevents the front edge of the sheet 2 from touching the suction bar 28 once it has passed the line of air openings 36’, 40’.

[0053] A vacuum pump may be connected to the first group of air openings 36. The first group of suction openings 36 may be connected to the vacuum pump via a common air duct 50. As illustrated in figure 4c, the air blowing openings 40’ are connected to a common air supply duct 50. The air supply duct 50 has a longitudinal extension coinciding with the longitudinal extension of the suction bar 28. The air supply duct 50 is positioned laterally and downstream of the suction compartment in the direction of transportation T. Each air blowing opening 40’ may be connected to a separate and inclined suction channel 41 .

[0054] In an advantageous embodiment, the loading surface 24 comprises air openings 52 located around the drive elements 30. A suction box can be located vertically below the air openings 52. The suction box may be further fluidically connected to the first group of suction openings 36 in the suction bar 28 through an air duct 51 . A suction device such as a vacuum generator may be connected to the suction box.

Claims

CLAIMS1. A feeder module (12) for a converting machine (1), the feeder module comprising: a loading surface (24) configured to receive a stack of sheets (2), a front stopper (26) configured to abut against the front edge of the stack and only allow the lowermost positioned sheet in the stack to be conveyed under the front stopper at a time, drive elements (30) configured to move the lowermost positioned sheet in the stack under the front stopper and forward in a direction of transportation (T), and wherein the feeder module comprises a suction bar (28) configured to apply suction against the lower side of the lowermost positioned sheet and direct the lowermost sheet under the front stopper, and wherein the suction bar comprises a first group of air openings (36) configured to apply suction against the lowermost sheet and a second group of air openings (40) configured to blow air against the lowermost sheet, and wherein the first group of air openings comprises a plurality of suction openings (36’) and the second group of air openings comprises a plurality of air blowing openings (40’).

2. The feeder module according to claim 1 , wherein the first group of air openings (36) and the second group of air openings (40) are arranged in a lateral direction (L) which is perpendicular to the direction of transportation (T).

3. The feeder module according to claim 2, wherein the first group of air openings (36) and the second group of air openings (40) are arranged in the same line and in an alternating manner such that a suction opening (36’) from the first group of air openings (36) is located in-between two air blowing openings (40’) from the second group of air openings (40).

4. The feeder module according to any one of the preceding claims, wherein the airflow rate through a suction opening (36’) is larger than the airflow rate through an air blowing opening (40’).

5. The feeder module according to any one of the preceding claims, wherein the first group of air openings (36) are provided with a funnel-shaped inlet.

6. The feeder module according to any one of the preceding claims, wherein the second group of air openings (40) have an oval orifice.

7. The feeder module according to any one of the preceding claims, wherein an absolute value of the air depression pressure (P1) at the orifice of a suction opening (36’) is lower than an absolute value of the positive pressure (P2) at the orifice of an air blowing opening (40’).

8. The feeder module according to any one of the preceding claims, wherein an air depression pressure (P1) in an air duct (51) connected to the orifice of a suction opening (36’) is between 3000 Pa and 5000 Pa, preferably about 4000 Pa, and wherein a positive pressure (P2) is present in an air supply duct (50) connected to an air blowing opening (40’) and is between 200000 and 500000 Pa, preferably around 400000 Pa.

9. The feeder module according to any one of the preceding claims, wherein the suction bar comprises an air conduit and a plurality of therefrom extending inclined channels (41), and wherein the inclined channels have an outlet which is formed by the orifices of the air blowing openings (40).

10. The feeder module according to the preceding claim, wherein the first group of air openings (36) is connected to a suction box which is also in fluidic communication with air openings (52) around drive elements (30) in the loading surface (24).

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