Suction rod system for converter

Abstract

The invention relates to a suction rod system for a switching machine (10), the suction rod system comprising at least one suction rod assembly (31) comprising a suction plate mounted on a cross beam having an internal air supply channel (34). The suction plate (36) comprises a plurality of main airflow channels (48), wherein each main airflow channel (48) is provided with a first suction opening (46a) and a second suction opening (46b). The main airflow channel (48) is provided with a constricted section (S2) having a first connection duct (50) configured to generate a pressure drop in the first suction opening (46a).

Description

Technical Field

[0001] The present invention relates to a conversion machine for producing box blanks and packaging blanks. In particular, the present invention relates to a suction bar system configured for holding blanks in a conversion machine. Background Art

[0002] Converting machines are used to produce packaging items such as paperboard and cartons. A flatbed press is a converting machine that can be configured to process blanks such as paperboard and corrugated board sheets. Specifically, a flatbed press is configured to punch blanks for boxes and packaging elements from sheets. A flatbed press is also sometimes referred to as a "die cutter."

[0003] A flatbed printing press comprises a plurality of processing units or stations. A conveying system is provided in such a machine to hold the blank and to convey the blank from one processing unit to the next processing unit.

[0004] The conveyor system helps to position the sheet so that the processing operation is performed on the correct position of the blank. The conveyor system may include a gripper bar configured to grasp the leading edge of the blank. The gripper bar holds the blank in the correct longitudinal and lateral position and conveys the blank according to predefined registration timing.

[0005] However, it is also desirable to use the suction rod to hold the trailing edge in place and prevent the sheet from bending or deforming. As the speed of the gripper rod changes, the blank tends to bend during deceleration.

[0006] Document WO20245116 A1 discloses a suction bar for holding the trailing edge of a sheet as it is transported through a flatbed printing press. The suction bar comprises a line with a plurality of air openings arranged side by side. However, the suction bar needs to be positioned at a specific vertical distance from the blank in order to hold the blank in place. Problems arise when the blank size and thickness change and the distance from the blank to the suction bar increases. Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a suction rod assembly having an improved ability to grasp and hold the trailing edge of a sheet material so that the suction force is suitable for holding sheets of different sizes.

[0008] This object is achieved by a suction rod system according to claim 1 and a positioning system according to claim 14 .

[0009] According to a first aspect of the invention, there is provided a suction rod system for a conversion machine, the suction rod system comprising at least one suction rod assembly, the suction rod assembly comprising a suction plate mounted on a crossbeam having an internal air supply channel,

[0010] The suction plate has a suction surface configured to apply suction to the blanks conveyed through the converting machine in a transport direction,

[0011] wherein the suction plate comprises a plurality of main air flow channels, each main air flow channel comprises an air inlet and an air outlet, the air inlet is connected to the air supply channel, and wherein the flow direction extends between the air inlet and the air outlet,

[0012] And wherein each main air flow channel is provided with a first suction opening and a second suction opening, the suction openings being arranged on the suction surface, and wherein the main air flow channel is provided with a contraction section having a first connecting duct connected to the first suction opening, and wherein the contraction section is configured to produce a pressure drop in the first suction opening.

[0013] The invention is based on the recognition that the gripping of the blank by the suction rod can be improved and performed faster by first reducing the amount of air present between the suction rod and the blank while simultaneously exerting a strong local suction force at the trailing edge of the blank.

[0014] In one embodiment, the main air flow channel has a cross-sectional area in the flow direction upstream of the second suction opening that is larger than the cross-sectional area of ​​the contraction section. The suction rod system is designed to generate a combined air flow from the inlet air flow and the air flow from the first suction opening, so that a large amount of air is injected through the main air flow channel at the second air flow opening. Therefore, the combined air flow reaches the second air opening through the connecting part and generates a high suction volume through the second air opening.

[0015] In one embodiment, the first suction openings and the second suction openings are arranged in separate lines perpendicular to the transport direction T. Thus, these lines are arranged in the longitudinal direction of the crossbeam.

[0016] In one embodiment, the converging section of the main air flow channel is a Venturi section.

[0017] The second suction opening is preferably connected to the main air flow channel via a second connecting duct.The connecting duct to the first suction opening is preferably located upstream of the connecting duct to the second suction opening in the flow direction.

[0018] In one embodiment, the first suction opening is located further downstream in the conveying direction than the second suction opening.

[0019] The internal air supply channel may have an inlet end connected to the air flow generator and may be provided with a plurality of distribution outlet openings configured to align with the air inlet openings on the suction plate.

[0020] Preferably, the suction plate is a separate component and is detachably mounted to the crossbeam.

[0021] In one embodiment, the first suction opening is arranged at a distance from the second suction opening, and wherein the distance is less than 10 times the diameter of the main air flow channel at the second suction opening.

[0022] The distance between the first suction opening and the second suction opening may differ between the main channels.

[0023] For example, the suction openings may be arranged in a staggered pattern so that the suction surface comprises a regular array of suction openings. This means that for some main channels the length of the distance segments may be different.

[0024] In one embodiment, the suction rod system may further comprise a deflection flange, and wherein the outlet opening of the main air flow channel is located below the deflection flange.

[0025] In one embodiment, the suction rod system may further include a shifting mechanism including a first sliding track and a second sliding track, and wherein the suction rod is slidably mounted on the sliding track.

[0026] According to a second aspect of the invention, a positioning system is provided, which comprises a suction rod system and a gripper unit, the gripper unit being configured to grip and position the leading edge of the blank, and wherein the suction rod system is positioned such that a first suction opening is further upstream than a second suction opening in a transport direction.

[0027] In one embodiment, the positioning system comprises a plurality of suction rod assemblies arranged along the transport direction.Therefore, a suction rod assembly is located in each workstation and is configured to hold the trailing edge of the blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will now be described with reference to the accompanying drawings, in which like features are indicated by like reference numerals, and in which:

[0029] - Figure 1 is a schematic cross-sectional view of a converter in a flatbed printing press configuration;

[0030] - Figure 2 is a schematic perspective view of a suction rod assembly according to one embodiment of the present invention;

[0031] - Figure 3 The cut-away portion shows Figure 2 A schematic perspective view of a suction plate of a suction rod assembly;

[0032] - Figure 4a is a schematic perspective view of a suction rod assembly installed in a conversion machine; and

[0033] - Figure 4b is a detailed cross-sectional view of the extraction plate connected to the airflow duct. DETAILED DESCRIPTION

[0034] The invention will be described with respect to a flatbed printing press converting machine. However, the invention can be integrated into other types of printing and folding modules for converting machines where it can be used to stabilize sheets and blanks during transport.

[0035] refer to Figure 1 , a conversion machine 10 in the form of a flatbed press 10 is shown. The flatbed press 10 is configured for converting a sheet 12 into a blank 12. The sheet 12 is thus converted into a final blank 12 as it is conveyed through the conversion machine 10. In the context of the present application, the term "blank" is used for an initial sheet 12 loaded into the conversion machine 10, an intermediate blank 12 in the conversion machine 10 and a final blank 12 produced by the conversion machine 10.

[0036] The conversion machine 10 consists of a plurality of workstations or units, each of which performs a specific operation on the blank 12. In the transport direction T of the blank 12, the conversion machine 10 comprises a feeder unit 10a, a flatbed press unit 10b, a stripping unit 10c, a blanking unit 10d and a waste discharge unit 10e.

[0037] Subsequently, the blanks 12 can be collected from the flatbed press 10 and introduced into a folder-gluer conversion machine where they are automatically glued and folded to form a folding box. Alternatively, the blanks 12 from the flatbed press 10 can be used as flat packaging boxes and can be folded manually.

[0038] The feeder unit 10a is configured to receive a stack of blanks 12 and feed them one by one into the flatbed printing unit 10b. The blanks 12 may be pre-printed with text or decorative features. Alternatively, the blanks 12 may be free of printed features. The flatbed printing unit 10b includes a die-cutting tool having a cutting and creasing blade configured to cut and crease the sheet 12.

[0039] The stripping unit 10c is configured for removing certain waste elements from the cut sheets 12. The blanking unit 10d is arranged after the stripping unit in the transport direction T and is configured for separating the blanks 12 from the cut waste and arranging the blanks 12 in a pile.

[0040] After the blanking unit 10d, the waste discharge unit 10e is configured to remove other waste elements of the cut sheet 12. The waste discharge unit 10e may include a conveyor for removing waste from the flat bed printing press.

[0041] The blanks 12 are conveyed through the conversion machine 10 by a conveyor system 18, which includes a conveyor belt 20, to which a plurality of gripper units 22 are attached. The gripper units 22 may also be referred to as "gripper bars" 22. The gripper units 22 are configured to grip the leading edge 12' of the blank 12 and convey the blank 12 through the conversion machine 10 in a guided manner. The gripper units 22 release the formed blank 12 at the blanking unit 10d. The gripper units 22 are spaced a fixed distance from each other so that the distance between the leading edges 12' of the blanks 12 is also fixed. The conveyor belt 20 is arranged above the blanks 12 and performs a track over the transport path of the blanks 12. The gripper units 22 transport the blanks 12 between different workstations and temporarily stop the blanks 12 when the flatbed press 10b is imprinting the blanks 12.

[0042] The trailing edge 12″ of the blank 12 is held by a suction rod system 30 including at least one suction rod assembly 31. The suction rod system 30 may include a plurality of suction rod assemblies 31. Preferably, the suction rod system 30 is located on the opposite side of the conveyor belt 20 having the gripper unit 22. In this way, interference and space limitations between the two systems 18, 30 can be reduced. In the illustrated embodiment, the suction rod system 30 is located below the blank 12.

[0043] Therefore, the conversion machine 10 can include a suction rod assembly 31 in the flatbed printing unit 10b, the peeling unit 10c and the blanking unit 10d, respectively. Each suction rod assembly 31 is positioned so that it holds the trailing edge 12" of the blank 12 in each corresponding workstation. Therefore, when the processing operation is performed on the blank 12, the trailing edge 12" of each blank 12 moving through the conversion machine 10 is held by the suction rod assembly 31.

[0044] The gripper unit 22 moves through the different workstations and performs a return path to return from the blanking unit 10d to the flatbed press unit 10b. The suction rod assembly 31 is fixed and located at an upstream position in each workstation 10b, 10c, 10d.

[0045] like Figure 4a As best shown, the position of the suction rod assembly 31 is preferably adjustable in the transport direction T. In this way, the position of the suction rod assembly 31 can be adapted to the longitudinal length L1 of the blank 12. A displacement mechanism 35 in the form of a first sliding track 35a and a second sliding track 35b can be arranged at the distal end 31a, 31b of the suction rod assembly 31 and engage with a mating connection part on the suction rod assembly 31.

[0046] Therefore, the blank 12 is held firmly and flatly between the gripper unit 22 and the suction rod assembly 31. This ensures that the punching operation performed by the flatbed press unit 10b provides the cutting and crease lines at the correct positions and that the cut blank 12 has the correct geometry.

[0047] The combination of the gripper unit 22 and the suction rod assembly 31 forms a positioning system.

[0048] like Figure 2 As shown, each suction rod assembly 31 includes an elongated crossbar 32 having an internal air supply duct 34 and a suction plate 36 including a suction surface S.

[0049] The suction surface S of the suction plate 36 is configured to apply suction to the blank 12 so that the trailing edge 12 ″ adheres thereto. The suction surface S on the suction plate 36 includes a plurality of suction openings 46 configured to apply suction to the blank 12 .

[0050] Preferably, only a portion of the longitudinal length L1 of the blank 12 is in contact with the suction surface S. During deceleration of the blank 12, the rear portion of the blank 12 in the transport direction T (e.g., about 75% of the longitudinal length L1 of the blank 12) may be in contact with the suction surface S. Thus, the front portion of the blank 12 (e.g., 25% of the longitudinal length L1) is not in contact with the suction surface S.

[0051] This allows the blank 12 to block the first suction opening 46a on the suction surface S and catch the rear of the blank 12. Therefore, the blank 12 is decelerated and straightened as the suction surface S catches the blank 12. The first suction opening 46a is located at a position at the trailing edge of the blank and close to the position where the blank 12 is temporarily stopped. In one embodiment, the position of the first suction opening 46a is located at a distance between 0 mm and 50 mm from the trailing edge of the blank 12, at which time the blank 12 is temporarily stopped.

[0052] The blank 12 is positioned at a vertical distance relative to the suction surface S of the suction plate 36. The vertical distance is measured between the blank 12 and the suction surface S at the attachment point of the gripper unit 22. The distance between the suction surface S and the blank 12 can be up to 16 mm. The suction force that draws the blank 12 to the suction bar assembly 31 is selected to be sufficient to keep the blank 12 flat.

[0053] The suction plate 36 is attached to the elongated beam 32. The connection between the suction plate 36 and the elongated beam 32 may be provided by fasteners 38, such as screws, bolts or rivets 38. The suction plate 36 may be removably mounted to the elongated beam 32.

[0054] The suction plate 36 may be produced by an additive manufacturing process (ie, a 3D printing process). This allows complex internal airflow channels to be formed in the suction plate 36. Alternatively, the suction plate 36 may be produced by other conventional manufacturing methods involving sheet metal forming or machining metal using tools.

[0055] exist Figure 2 In the example shown, a plurality of suction plates 36 are mounted on the top surface of the elongated cross beam 32. However, a single suction plate 36 may also be provided, which extends over the length of the elongated cross beam 32 in the longitudinal direction L. The longitudinal direction L and the longitudinal extension of the suction bar assembly 31 are perpendicular to the transport direction T.

[0056] The air supply duct 34 is provided with an air inlet 33 which is connected to an air flow generator (not shown). A plurality of air outlet openings 40 are arranged on the top surface of the elongated cross beam 32. The air outlet openings 40 from the air supply duct 34 are configured to mate with matching air inlet openings 42 in the suction plate 36 (at Figure 3 Preferably, a seal 44 is arranged between the air supply duct 34 and the suction plate 36. The seal 44 comprises a hole at a position where the air outlet opening 40 is aligned with the air inlet opening 42.

[0057] The suction openings 46 include a first group of suction openings 46a and a second group of suction openings 46b. The first group of suction openings 46a and the second group of suction openings 46b may be arranged in a straight line, the straight line extension of which is consistent with the longitudinal extension of the suction rod assembly 31.

[0058] Alternatively, the first suction openings 46a may be staggered in the longitudinal extension of the suction rod assembly 31. In this way, the suction surface S comprises a regular array of suction openings 46a, 46b. This can be achieved by providing a varying distance d1 ( Figure 3 The second suction openings 46b can also be arranged in a staggered manner.

[0059] The first group of suction openings 46a and the second group of suction openings 46b may be positioned at an upstream position in each workstation, which allows the gripper unit 22 to position the leading edge of the blank 12 at the exit of each workstation while the suction openings 46a, 46b apply suction and grasp the trailing edge of the blank 12. The first group of suction openings 46a is configured to apply a suction force to the blank 12 so that the blank 12 adheres against the suction surface S of the suction bar assembly 31. The first group of suction openings 46a is preferably arranged further downstream than the second group of suction openings 46b in the transport direction T. The suction force is selected to keep the blank 12 flat and prevent the trailing edge of the blank 12 from lifting.

[0060] The second set of suction openings 46 b is configured to generate a large outflow of air, thereby reducing the amount of air between the blank 12 and the suction rod assembly 31 by suction.

[0061] The pressure in the first group of suction openings 46a is lower than the pressure in the second group of suction openings 46b. In one embodiment, the pressure in the first suction openings 46a can be between 0mbar and -600mbar, preferably between -40mbar and -200mbar. The pressure in the second suction openings 46b is between 0mbar and -150mbar, preferably between 0mbar and -40mbar.

[0062] This pressure difference is achieved by a specific channel design in the suction plate 36. Figure 3 As best shown, the suction plate 36 includes a plurality of main airflow channels 48 extending from an inlet opening 42 to an outlet opening 43. The inlet opening 42 is connected to the central air supply duct 34 as previously described. The outlet opening 43 may be located below a flange 47 in the suction wand assembly 31. The flange 47 may be in the form of a plate-like element and is configured to disperse the outlet airflow from the main airflow channels 48.

[0063] The air flow rate through the first suction opening 46a and the second suction opening 46b may be as high as 3000 l / min.

[0064] Each main airflow channel 48 has a plurality of segments S1 to S6 along the airflow direction F, and the plurality of segments S1 to S6 have different geometric shapes. In the direction from the inlet opening 42 to the outlet opening 43, the main airflow channel 48 includes an inlet segment S1, a contraction segment S2, a first connecting segment S3, a distance segment S4, a second connecting segment S5, and an outlet segment S6.

[0065] The inlet section S1 can be bent so that the inlet opening 42 is vertically aligned with the air supply opening 40 in the suction rod assembly 31. The inlet section S1 allows the inlet airflow Q1 to be guided into the main airflow channel 48. In the inlet section S1, the inlet airflow Q1 is received. The pressure in the inlet section S1 is similar to the pressure in the air supply channel 34, and the airflow velocity v1 is selected according to the cross-sectional area of ​​the inlet section S1.

[0066] The contraction section S2 is a Venturi section configured to provide acceleration of the airflow, thereby increasing the air velocity. The contraction section S2 is funnel-shaped so that the cross-sectional area of ​​the main airflow channel 48 gradually decreases along the airflow direction F. The airflow velocity v2 in the contraction section S2 is higher than the airflow velocity v1 in the inlet section S1, and the pressure in the contraction section S2 is reduced to be lower than the pressure in the inlet section S1. The flow rate Q2 through the contraction section S2 is equal to the flow rate Q1 in the inlet section S1.

[0067] The first connecting section S3 comprises a connecting duct 50 extending from the main air flow channel 48 to the first suction opening 46a. The inlet of the first connecting section S3 is located at the outlet of the contraction section S2. Therefore, the first suction opening 46a is connected to the outlet of the contraction section S2. The reduced pressure at the outlet of the contraction section S2 causes a pressure drop in the first connecting duct 50. This generates a high suction force through the first suction opening 46a.

[0068] Therefore, additional airflow Q2 is sucked into the main airflow channel 48 through the first suction opening 46a. This provides an increased airflow in the connecting section S3. The airflow Q3 through the first connecting section S3 is equal to the sum of Q1 and Q2. The cross-sectional area of ​​the connecting section S3 is also larger than the cross-sectional area of ​​the contraction section.

[0069] The distance segment S4 is provided with a substantially constant cross-sectional area and ensures that the first suction opening 46a is spaced apart from the second suction opening 46b by a distance d1. The distance d1 can be selected, for example, to be long enough to reduce the airflow turbulence at the end of the distance segment S4. The distance d1 is preferably less than 10 times the diameter d2 of the main airflow channel 48 at the second suction opening 46b.

[0070] The second connection section S5 to the second suction opening 46b is located at the outlet of the distance section S4. The cross-sectional area of ​​the distance section S4 is larger than the inlet section S1, and the airflow Q5 through the second connection section S5 is higher than the inlet airflow Q1. This results in a higher air outflow Q4 through the second suction opening 46b. In one embodiment, there may be a plurality of second suction openings 46b connected to each main airflow channel 48.

[0071] The outlet section S6 is configured to disperse the airflow through the outlet opening 43. The airflow Q5 in the outlet section S6 is the sum of the inlet airflow Q1 and the airflows Q2 and Q4 provided through the first and second suction openings 46a, 46b.

Claims

1. A suction rod system (30) for a conversion machine (10), the suction rod system comprising at least one suction rod assembly (31), the suction rod assembly comprising a suction plate (36) mounted on a crossbeam (32), the crossbeam having an internal air supply channel (34), The suction plate has a suction surface (S) configured to apply suction to a blank (12) conveyed through the conversion machine (10) in a transport direction (T), wherein the suction plate (36) comprises a plurality of main air flow channels (48), each main air flow channel comprising an air inlet (42) and an air outlet (43), the air inlet being connected to the air supply channel (34), and wherein a flow direction (F) extends between the air inlet (42) and the air outlet (43), And each main air flow channel (48) is provided with a first suction opening (46a) and a second suction opening (46b), the suction openings (46a, 46b) are arranged on the suction surface (S), and wherein the main air flow channel (48) is provided with a contraction section (S2), the contraction section has a first connecting pipe (50) connected to the first suction opening (46a), and wherein the contraction section is configured to generate a pressure drop in the first suction opening (46a).

2. The suction rod system according to claim 1, wherein the cross-sectional area (A2) of the main airflow channel in the flow direction (F) upstream of the second suction opening (46b) is greater than the cross-sectional area (A1) of the contraction section (S2).

3. The suction bar system according to claim 1 or 2, wherein the first and second suction openings (46a, 46b) are arranged on separate lines perpendicular to the transport direction (T).

4. The suction rod system according to any of the preceding claims, wherein the contraction section (S2) of the main airflow channel is a Venturi section.

5. The suction wand system according to any of the preceding claims, wherein the second suction opening (46b) is connected to the main air flow channel via a second connecting duct (51).

6. Suction rod system according to claim 5, wherein the connecting duct (50) to the first suction opening is located upstream of the connecting duct (51) to the second suction opening in the flow direction (F).

7. The suction bar system according to any of the preceding claims, wherein the first suction opening (46a) is positioned further downstream in the transport direction (T) than the second suction opening (46b).

8. A suction rod system according to any of the preceding claims, wherein the internal air supply channel (34) has an inlet end (33) connected to an airflow generator and is provided with a plurality of distribution outlet openings (40), which are configured to be aligned with the air inlet openings (42) on the suction plate.

9. A suction bar system according to any one of the preceding claims, wherein the suction plate is a separate component and is removably mounted to the crossbar.

10. The suction rod system according to any of the preceding claims, the first suction opening being arranged at a distance (d1) from the second suction opening, and wherein the distance is less than 10 times the diameter (d2) of the main airflow channel at the second suction opening.

11. The suction wand system according to any of the preceding claims, wherein the distance (d1) between the first suction opening and the second suction opening is different between the main channels.

12. The suction rod system according to any of the preceding claims, further comprising a deflection flange (47), and wherein the outlet opening of the main air flow channel is located below the deflection flange.

13. The suction rod system according to any of the preceding claims, further comprising a displacement mechanism (35), the displacement mechanism comprising a first and a second sliding track (35a, 35b), and wherein the suction rod is slidably mounted on the sliding track.

14. A positioning system comprising a suction rod system and a gripper unit according to any one of the preceding claims, the gripper unit (22) being configured to grasp and position the leading edge of the blank, and wherein the suction rod system is positioned so that the first suction opening (46a) is further downstream than the second suction opening (46b) in the transport direction.

15. Positioning system according to the preceding claim, wherein a plurality of suction rod assemblies (31 ) are arranged along the transport direction (T).

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