Reverse transfer module for converting machine

Abstract

The present invention relates to a reversing transport module (60) for a converter having a printing module (16), the printing module (16) comprising a first printing unit (17) arranged for printing on the top side (S1) of a sheet (1) and a second printing unit (17') arranged for printing on the bottom side (S2) of the sheet. The reversing transport module is arranged between the first printing unit and the second printing unit and includes a first reversing vacuum transport device (62) arranged to contact a first side of the sheet and a second reversing vacuum transport device (64) arranged to contact a second side of the sheet, thereby configuring the reversing transport module to change the adsorption and transport sides of the sheet.

Description

Technical Field

[0001] This invention relates to a conversion machine suitable for the production of paper or cardboard boxes having printed patterns on both the inner and outer surfaces. Background Technology

[0002] In the packaging industry, boxes are typically made from corrugated cardboard or cardboard sheet substrates. There are two main types of boxes: folding slotted boxes (sometimes also called "folding boxes") and flat-pack boxes. Folding slotted boxes are folded and glued together in a conversion machine, while flat-pack boxes are provided as flat sheets from the conversion machine and are subsequently folded and, if possible, closed (e.g., with tape) when they are provided with their final contents.

[0003] This invention relates to a conversion machine including a printing unit. Such a conversion machine can be configured as a rotary die-cutting machine suitable for producing printed flat-pack boxes, or as a flexographic folding and adhesive conversion machine for producing folded, slotted boxes. Taking a rotary die-cutting machine as an example, it includes a series of modules, including a feeder module, a flexographic printing module, a die-cutting module, and typically a stacker module.

[0004] Cardboard or cardboard boxes typically have printed designs on their outer surfaces. In a standard outer printing process, the flexographic printing cylinder in the transfer press is usually located below the sheet and is configured to print on the bottom side of the sheet. The bottom side of the sheet then represents the outer surface of the box.

[0005] Sometimes it is also desirable to print on the inside of the box. By printing on the inside, further information or decorative patterns can be provided on the inner surface of the box. In order to print on both the outside and inside of the box, the flexographic printing module also needs to include at least one additional flexographic printing unit with printing cylinders arranged to print on the top side of the sheet.

[0006] When printing on a sheet from below, the sheet needs to be fed on the top side. Conversely, if the sheet is to be printed on the top surface, it needs to be fed on the bottom side.

[0007] The transport and suction of the sheet are partially achieved using a transport element and a vacuum suction unit, which are configured to apply suction against the bottom and top sides of the sheet in an alternating manner. This arrangement drives and holds the sheet in a desired vertical position against the printing cylinder inside the converter.

[0008] For double-sided printing processes, the transport side of the sheet needs to be changed / switched between the upper and lower flexographic printing cylinders. However, this change in transport and adsorption causes the sheet to change orientation vertically. This can lead to interruptions, such as unwanted registration misalignment and further misalignment in downstream printing, die-cutting, and creasing operations. Summary of the Invention

[0009] In view of the above problems, the object of the present invention is to provide a transfer machine for smooth and controlled transport of sheet material between a top printing cylinder and a bottom printing cylinder.

[0010] The objective of this invention is achieved through a reverse transmission module.

[0011] According to a first aspect of the invention, a reversing transport module for a converter having a printing module is provided, the printing module comprising at least one first printing unit arranged for printing on the top side of a sheet and at least one second printing unit arranged for printing on the bottom side of the sheet.

[0012] The reverse transfer module is configured to transport a sheet between at least one first printing unit and at least one second printing unit, wherein the reverse transfer module includes an inlet reverse vacuum transfer device and an outlet reverse vacuum transfer device, each configured to contact and transfer different sides of the sheet, thereby the reverse transfer module is configured to change the sides of the sheet for adsorption and transport.

[0013] In one embodiment, the printing module is a flexographic printing module, wherein the first printing unit includes a top printing roller arranged to print on the top side of the sheet, and the second printing unit has a bottom printing roller arranged to print on the bottom side of the sheet.

[0014] In one embodiment, the reverse transfer module further includes a pivotally movable locking member connected to the housing of the reverse transfer module. The pivotally movable locking member can be configured to engage with a corresponding mating geometry in the printing module to mechanically connect the housing of the reverse transfer module to the housing of the printing unit.

[0015] In one embodiment, the reverse transfer module further includes a first deflector, which is arranged at an angle and defines an inlet gap and an outlet gap with the inlet reverse vacuum transfer device, wherein the inlet gap is greater than the outlet gap, thereby providing a funnel-shaped inlet channel to the outlet reverse vacuum transfer device.

[0016] In one embodiment, the reverse transfer module includes a horizontally arranged second deflector that defines an inlet gap and an outlet gap with the outlet reverse transfer device, wherein the deflector is parallel to the outlet reverse vacuum transfer device.

[0017] In this embodiment, the inlet reverse vacuum transfer device is connected to the first vacuum generator, and the outlet reverse vacuum transfer device is connected to the second vacuum generator.

[0018] In one embodiment, the vacuum suction of the reverse vacuum conveying device configured to apply suction to the top side of the sheet is higher than that of the reverse vacuum conveying device configured to apply suction to the bottom side of the sheet.

[0019] In one embodiment, the reversing transfer module further includes a structural frame, wherein the upper reversing vacuum transfer device and the lower reversing vacuum transfer device are mounted on the same structural frame. The structural frame is separated from the flexographic printing module.

[0020] In this implementation, the reversing conveyor module is equipped with a shifting device that enables horizontal shifting of the reversing conveyor module. The shifting device can be a wheel, roller, or guide rail.

[0021] In one embodiment, the housing of the reverse vacuum conveying device configured to apply suction to the top side of the sheet includes a separate suction compartment connected to an upper vacuum generator.

[0022] The compartment may be defined by an internal wall extending in the transport direction and arranged such that a centrally located suction compartment is provided, which is positioned between a first lateral suction compartment and a second lateral suction compartment.

[0023] In one embodiment, the inner wall is configured as a movable shutter, wherein suction from the vacuum generator can be distributed to the first lateral suction chamber and the second lateral suction chamber by opening the shutter.

[0024] According to a second aspect of the invention, a conversion machine is provided for printing and converting sheet material into packaging elements for boxes, the conversion machine comprising:

[0025] - A printing module, comprising a first printing unit arranged for printing on the top side of a sheet and a second printing unit arranged for printing on the bottom side of a sheet.

[0026] - A conveying system configured to transport a sheet through a transducer along a conveying path in the transport direction. The conveying system includes a first conveying unit and a second conveying unit. The first conveying unit is configured to contact and transport the sheet on its bottom side, and the second conveying unit is configured to contact and transport the sheet on its top side. Each conveying unit includes a drive element configured to move the sheet forward in the transport direction and a vacuum orifice arranged to attract the sheet to the drive element.

[0027] The converter further includes a reversing conveyor module arranged between the first printing unit and the second printing unit. The reversing conveyor module includes an inlet reversing vacuum conveyor and an outlet reversing vacuum conveyor, each configured to contact and transport different sides of the sheet, thereby changing the sides of the sheet for adsorption and transport.

[0028] This invention is based on the understanding that controlled changes to the sheet conveying side can be achieved in a dedicated module configured to control the sheet conveying. Therefore, the reverse conveying module vertically shifts the sheet while changing the conveying side.

[0029] The packaging element can be a flat box, a folding slotted box, or a collapsible box. The packaging element is preferably made of cardboard or paperboard.

[0030] In one embodiment, the printing module is a flexographic printing module, wherein the first printing unit includes a top printing roller arranged to print on the top side of the sheet, and the second printing unit has a bottom printing roller arranged to print on the bottom side of the sheet.

[0031] In one embodiment, the printing module is a lithographic printing module, wherein the first printing unit includes a top printing roller arranged to print on the top side of the sheet, and the second printing unit has a bottom printing roller arranged to print on the bottom side of the sheet.

[0032] In one embodiment, the first printing unit is an inkjet printing unit configured to print on the top side of the sheet, and the second printing unit is a flexographic printing module configured to print on the bottom side of the sheet.

[0033] In one embodiment, the converter is configured as a rotary die-cutting machine. In another embodiment, the converter is configured as a flexographic folding adhesive machine.

[0034] In one embodiment, the first flexographic printing unit is arranged upstream of the second flexographic printing unit in the transport direction, and the inlet reversing vacuum conveyor is configured to apply suction to the bottom side of the sheet. The inlet reversing vacuum conveyor is thus configured to cause the bottom side of the sheet to adhere to the drive roller or conveyor belt of the inlet reversing conveyor.

[0035] In this implementation, the inlet reversing vacuum conveyor is driven in tandem with the adjacent conveyor unit of the nearest upstream printing unit. The speed of the inlet reversing vacuum conveyor is equal to the speed of the conveyor unit of the nearest upstream printing unit.

[0036] In this implementation, the exit reversing vacuum conveyor can be driven in sync with the conveyor unit of the nearest downstream printing unit. The speed of the exit reversing vacuum conveyor is equal to the speed of the conveyor unit of the nearest downstream flexographic printing unit.

[0037] In one embodiment, the converter also includes a die-cutting module located downstream of the printing module in the transport direction.

[0038] In one embodiment, the converter includes a movable part and a fixed part, and a reversing transfer module is arranged as a switching element between the movable part and the fixed part. The movable part includes a module that can move on the floor. The fixed part includes a module that is fixedly mounted on the floor.

[0039] In this implementation, the reverse conveyor module is equipped with a shifting device, enabling the reverse conveyor module to be horizontally shifted relative to the flexographic printing unit. The shifting device can be a wheel, roller, or slide rail. Attached Figure Description

[0040] Further advantages and features will become apparent from the following description of exemplary embodiments of the invention and the accompanying drawings, wherein like features are indicated by like reference numerals, wherein:

[0041] Figures 1a and 1b show the flat packaging box before and after assembly, respectively;

[0042] Figure 1c shows a schematic diagram of the stacking of sheet substrates;

[0043] Figure 2 An example of a converter configured as a rotary die-cutting machine is shown;

[0044] Figure 3 A schematic perspective view of the flexographic printing module is shown;

[0045] Figure 4 A schematic perspective view of the flexographic printing assembly is shown;

[0046] Figure 5 A schematic diagram of an embodiment of the vacuum transfer device is shown;

[0047] Figure 6 This is a schematic cross-sectional view of a reverse transmission module according to an embodiment of the present invention;

[0048] Figure 7a This is a detailed cross-sectional view of the reverse transmission module according to an embodiment of the present invention;

[0049] Figure 7b This is a detailed view of the conversion between the bottom reversing vacuum conveyor and the top vacuum reversing conveyor;

[0050] Figure 8a and 8b A schematic cross-sectional view of the locking device between the reverse transfer module and the flexographic printing unit is shown;

[0051] Figure 9 yes Figure 7a A schematic perspective view of the reverse transmission module from the entrance side;

[0052] Figure 10 This is a schematic perspective view of the reverse transmission module from the exit side;

[0053] Figure 11 yes Figure 9 and Figure 10 A schematic cross-sectional view of the reverse transmission module;

[0054] Figure 12a and 12b This is a schematic cross-sectional view of a flexographic printing unit for top printing according to an embodiment of the present invention, wherein the printing components are respectively in the printing and repair positions;

[0055] Figure 13a and 13b yes Figure 12a and 12b A schematic side view of the structural framework of the flexographic printing unit;

[0056] Figure 14 It comes from Figure 12a and 12b A schematic front view of the structural framework; and

[0057] Figure 15 yes Figure 14 A schematic perspective view of the structural framework. Detailed Implementation

[0058] Referring now to Figures 1a and 1b, which show examples of a flat packaging box 1” and a box 1' obtained by folding the flat packaging box 1”. As can be seen from the figures, the flat packaging box 1' includes folded edges 2, cut outer edges 4 providing the overall shape of the box 1', and may further include (e.g., slits 5 for a handle). The flat packaging box 1” is obtained from a sheet substrate 1, such as the sheet substrate shown in Figure 1c. The sheet substrate 1 is a square or rectangular sheet of cardboard or paperboard.

[0059] In converter 10 (e.g.) Figure 2The flat packaging box 1” of FIG1b is manufactured in the converter 10 shown. In the entry position of the converter 10, the unprocessed cardboard or cardboard sheet substrate 1 is placed in the feeder module 14 and conveyed in the transport direction D to undergo a series of operations of printing, cutting and folding the sheet substrate 1.

[0060] Figure 2 The converter 10 shown is configured as a rotary die-cutting machine. However, in another embodiment not shown, the converter 10 can be configured as a flexographic folding adhesive machine. Figure 2 The converter 10 includes multiple different modules or workstations that provide different processing steps to the sheet substrate 1 as it is transported through the converter 10.

[0061] From the entrance of the converter 10 and downstream along the transport direction D, the converter 10 may include a pre-feeder 12, a feeder module 14, a flexographic printing module 16 including at least one flexographic printing unit 17, a die-cutting module 18, a stacker 20, and a stacker-crusher module 22. A main operator interface 11 may also be located near the converter 10.

[0062] Prior to the stacker-crusher module 22, the sheet substrate 1 can be in the form of an intermediate blank having multiple flat packaging boxes 1 arranged side by side. Figure 1b shows the shape of the intermediate blank obtained prior to the stacker-crusher module 22. Multiple crease lines 2 and cutting lines 4 are provided on the surface of the intermediate blank. To separate the first blank from the second blank, perforation lines 3 can be provided and can be broken in the stacker-crusher module 22.

[0063] Paper or cardboard substrate in the form of sheets 1 is introduced into the converter 10 by the feeder 14, which feeds the sheets 1 one by one at a predefined interval. In order to continuously supply the sheets 1, stacks of the sheets are placed in the feeder 14.

[0064] The flexographic printing module 16 can be arranged after the feeder module 14 and configured to print on one side of the sheet 1. Typically, in current commercially available conversion machines, the sheet 1 is printed on the outer side that will become the box.

[0065] like Figure 3As best shown, the flexographic printing module 16 may include at least one flexographic printing unit 17. Preferably, the flexographic printing module 16 includes a plurality of flexographic printing units 17a, 17b to 17n, enabling printing in different colors. For example, the flexographic printing unit 17 may use custom inks or a CMYK color model to achieve color printing with cyan, magenta, yellow, and key (black) inks. The flexographic printing unit 17 includes an outer housing 24 and a structural frame 100 on which the flexographic printing assembly 28 (such as...) is mounted. Figure 4 (As shown).

[0066] exist Figure 4 An exemplary bottom-printing flexographic printing assembly 28 for a flexographic printing unit 17, as known in the art, is shown. The flexographic printing assembly 28 includes a printing cylinder 30 having an attachment bracket 38 on which a printing plate 31 can be mounted. The printing plate 31 is provided with a printing die configured for printing a specific pattern on a sheet 1. An anilox cylinder 34 is arranged near the printing cylinder 30 and configured to draw and transfer ink from a liquid supply device (such as a doctor blade chamber 36) to the printing plate 31.

[0067] The anvil 32 (also known as the reverse roller) is arranged adjacent to the printing roller 30 and is configured to back / press the sheet 1 against the printing roller 30 and ensure that the pattern is transferred onto the sheet 1.

[0068] like Figure 2 and Figure 5 As shown, the converter 10 further includes a conveying system configured to transport the sheet 1 along a conveying path P passing through the converter 10 in a transport direction D. The transport direction D is defined as from the inlet to the outlet of the converter 10. Therefore, the conveying path P can extend from the feeder module 14 toward the die-cutting module 18 and further to the delivery table. The conveying system includes drive elements (such as an annular belt conveyor and rollers) to convey the sheet 1 through the converter 10. The conveying system may include multiple individual transport segments, referred to as conveyor units 40. In particular, conveyor units 40 include a series of conveyor units 66, 68 located in the flexographic printing units 17, 17'. The conveyor units 66, 68 may be in the form of vacuum conveyor units 66, 68. The conveying system further includes vacuum conveyor units arranged between different workstations.

[0069] The conveying device 40 includes a drive element 42, such as a drive roller 42, and a plurality of suction holes 46 arranged around the drive roller 42. The suction holes 46 are configured to hold the sheet 1 firmly against the drive roller 42. Alternatively, a conveyor belt may be used instead of the drive roller 42.

[0070] The conveying device 40 also includes a transport surface 50, which may be a smooth metal surface. The drive roller 42 is located on the side opposite to the side of the printing roller 30. This allows the drive roller 42 to transport the sheet 1 on the "dry side," which is therefore opposite to the side currently being printed by the printing plate 31. Therefore, when the sheet 1 needs to be printed on both the bottom side S2 and the top side S1, the transport side of the sheet 1 needs to be changed in the changeover machine 10.

[0071] Now for reference Figure 6 , Figure 6 A cross-sectional view of a printing module 16 according to an embodiment of the present invention is shown. As shown, the printing module 16 may be in the form of a flexographic printing module 16.

[0072] The flexographic printing module 16 includes a first flexographic printing portion 16a and a second flexographic printing portion 16b.

[0073] The first flexographic printing section 16a includes at least one flexographic printing unit 17 configured in a top printing arrangement. The second flexographic printing section 16b includes at least one flexographic printing unit 17' configured in a bottom printing arrangement.

[0074] The first flexographic printing portion 16a is therefore configured to print on the upper side S1 of the sheet 1, while the second flexographic printing portion 16b is configured to print on the bottom side S2 of the sheet 1. In this case, the upper side S1 can represent the inside of the box, and the bottom side S2 of the sheet can represent the outside of the box.

[0075] The first flexographic printing section 16a may include one or more flexographic printing units 17, such as four (17a, 17b, 17c, 17d), enabling the use of different inks. Similarly, the second flexographic printing section 16b may also include one or more flexographic printing units 17'.

[0076] The reverse transfer module 60 is arranged between the last flexographic printing unit 17 of the first flexographic printing section 16a and the first flexographic printing unit 17' of the second flexographic printing section 16b.

[0077] For double-sided printing, the conveying system includes a first set of conveying devices 40 configured to contact and convey the sheet 1 on its top side S1 and a second set of conveying devices 40 configured to convey the sheet 1 on its bottom side S2. The flexographic printing module 16 includes these two sets of conveying devices 40 to transport the sheet 1 on the side opposite to the side being printed. For this purpose, the first set of conveying devices includes a first conveying unit 66 located in the first flexographic printing unit 17 and configured to contact and convey the sheet 1 on its bottom side S2. Similarly, the second flexographic printing unit 17' includes a second conveying unit 68 configured to transport the sheet 1 on its top side S1. The conveying units 66 and 68 are typically vacuum conveying units and are configured to cause the sheet 1 to adhere to the drive roller 42.

[0078] Even though the present invention is described and shown using a top printing unit 17 arranged in front of a bottom printing unit 17', the converter 10 can also be configured to have a bottom printing unit 17' arranged in front of the top printing unit 17 in the transport direction D. In this case, the shown reverse conveyor module 60 is arranged in a reverse / mirror manner.

[0079] However, arranging the top printing portion 16a in front of the bottom printing portion 16b provides better accuracy at the die-cutting module 18. Since the sheet 1 is attracted and transported on its top surface S1 when it arrives at the die-cutting module 18, the sheet 1 can also be positioned closer to the top-mounted rotary die-cutting tool. This provides better transport of the sheet 1 and a more accurate position of the sheet 1 at the die-cutting module 18.

[0080] Alternatively, in embodiments not shown, the printing module 16 may be in the form of an offset printing module. The offset printing module may have a first printing unit configured to print on the top side S1 of the sheet 1 and a second printing unit configured to print on the bottom side S2 of the sheet 1.

[0081] In another embodiment, the printing module 16 may include a first printing unit in the form of an inkjet printing unit configured to print on the top side S1 of the sheet 1 and a flexographic printing unit configured to print on the bottom side S2 of the sheet 1.

[0082] The reversing conveyor module 60 includes a bottom reversing vacuum conveyor 62 configured to contact the bottom side S2 of the sheet 1 and a top reversing vacuum conveyor 64 configured to contact the top side S1 of the sheet 1. The bottom reversing vacuum conveyor 62 and the top reversing vacuum conveyor 64 of the reversing conveyor module 60 can change the transport side of the sheet 1. Therefore, the reversing conveyor module 60 changes the adsorption side of the sheet 1 from the upstream conveying unit 66 of the first printing section 16a to the downstream conveying unit 68 of the second printing section 16b. In the illustrated embodiment, the bottom reversing vacuum conveyor 62 is configured as an inlet vacuum conveyor, and the top reversing vacuum conveyor 64 is configured as an outlet vacuum conveyor in the transport direction D.

[0083] like Figure 7a and 7b As shown, the inlet reverse vacuum conveyor 62 and the outlet reverse vacuum conveyor 64 are mounted on the structural frame 70. The vertical distance d2 between the inlet reverse vacuum conveyor 62 and the outlet reverse vacuum conveyor 64 in the reverse conveyor module 60 is chosen such that the typical maximum thickness of the sheet 1 can pass through the gap between the inlet reverse vacuum conveyor 62 and the outlet reverse vacuum conveyor 64. Typically, this gap distance d2 can be about 10 mm, which corresponds to the common maximum cardboard thickness.

[0084] like Figure 7a , 7b As shown in 8a and 8b, the reverse transfer module 60 may further include at least one locking mechanism 71 for mechanically connecting the reverse transfer module 60 to the nearest upstream flexographic printing unit 17. The locking mechanism 71 includes a movable locking member 72 attached to a rod 73 and a piston actuator 74. The locking member 72 is positioned on a first end 73a of the rod 73, while a second end 73b of the rod is fixedly but rotatably mounted in the housing 61 of the reverse transfer module 60 and defines the axis of rotation A of the rod 73. The piston actuator 74 is connected to the first end 73a of the rod 73. The piston actuator 74 can be actuated such that the locking member 72, disposed on the first end 73a, moves in a circular path and in a vertical direction. The structural frame 100 of the printing unit 17 includes a mating geometry corresponding to the locking member 72, enabling locking between the reverse transfer module 60 and the structural frame 100 of the printing unit 17.

[0085] Therefore, the piston actuator 73 forces the structural frames 70, 100 or housings 61, 19 of the reverse transfer module 60 and the printing unit 17 into contact with each other. Thus, the piston actuator 74 can be actuated until a stop is sensed, and thus indicates that the housings 61, 19 are in contact with each other.

[0086] To achieve uniform connection, the reverse transmission module 60 may include two locking mechanisms 71 located on each side of the lateral side of the reverse transmission module 60.

[0087] In an embodiment not shown, a similar locking mechanism 71 may be located on the downstream side of the reverse transfer module 60 and actuated to lock the reverse transfer module 60 to the nearest downstream flexographic printing unit 17' of the second flexographic printing section 16b. This locking mechanism may be advantageously used if the nearest downstream flexographic printing unit 17' of the reverse transfer module 60 is movable (i.e., movable on the floor).

[0088] The locking mechanism 71 allows the reversing conveyor module 60 to be released from the flexographic printing units 17, 17'. If the flexographic printing units 17, 17' are movable (i.e., movable on the floor), they can be moved away from the reversing conveyor module 60 or adjacent flexographic printing units 17 after being released (in the transport direction D). If the reversing conveyor module 60 is movable, it can also be moved. Such operation may be necessary to access the printing plate 31 on the flexographic printing cylinder 30, or for general maintenance procedures.

[0089] like Figure 6 As shown, the converter 10 may include a movable portion 20a and a fixed portion 20b, and a reverse transfer module 60 may be arranged as a transition element between the movable portion 20a and the fixed portion 20b. The movable portion 20a may be configured to include a module from the feeder 14 to the last flexographic printing unit 17 in the first flexographic printing section 16a. The fixed portion 20b may be configured to include the reverse transfer module 60 and the flexographic printing unit 17' in the second flexographic printing section 16b. The module of the movable portion 20a may have rollers or wheels 13 for displacement on the floor. Alternatively, instead of wheels, the module in the movable portion 20a may be slidably mounted on the floor via a slide rail connection. Optionally, the reverse transfer module 60 may be provided with wheels 13 for displacement on the floor.

[0090] The inlet reverse vacuum transfer device 62 and the outlet reverse vacuum transfer device 64 are connected to at least one vacuum source 76a, 76b via vacuum tube 33. In the illustrated embodiment, the inlet reverse vacuum transfer device 62 may be connected to a first vacuum generator 76a, and the outlet reverse vacuum transfer device 64 may be connected to a second vacuum generator 76b. Alternatively, a single vacuum generator and at least one valve may be used to distribute and regulate the vacuum suction between the inlet and outlet reverse vacuum transfer devices 62, 64.

[0091] Vacuum generators 76a and 76b can be configured to provide a variable vacuum force. Specifically, converter 10 can be configured to receive different settings, allowing modification of the vacuum force and the area of ​​the vacuum force. This setting can be modified based on the dimensions (i.e., sheet area), weight, and surface quality of sheet 1. Regarding surface quality, generally, smooth surfaces will adhere more strongly to the vacuum hole 46 than rough surfaces. Vacuum generators 76a, 76b, or generator 76 can provide a variable vacuum force in response to a variable rotation speed setting.

[0092] As in Figure 10 and Figure 11 As best viewed from the center, the housing 61 of the upper inverted vacuum transfer device 64 may include separate suction chambers 80, 82, 84 connected to the vacuum generator 76b. The internal walls 86, 88 extending in the transport direction D are arranged such that the centrally located suction chamber 80 is positioned and disposed between the first lateral suction chamber 82 and the second lateral suction chamber 84.

[0093] The central suction compartment 80 is provided with separation walls 86, 88 that abut against the first lateral suction compartment 82 and the second lateral suction compartment 84. The separation walls 86, 88 are configured as movable gates 86, 88 and are configured to provide openings of varying degrees. The gates 86, 88 may be pivotally movable.

[0094] Gates 86 and 88 control the position of the suction force. The central suction chamber 80 can be directly connected to the vacuum generator 76b. Gates 86 and 88 are opened to distribute negative pressure to the first and second lateral suction chambers 82 and 84. Therefore, when gates 86 and 88 of the central suction chamber 80 are opened, a vacuum is generated in the lateral suction chambers 82 and 84.

[0095] Gates 86 and 88 allow for selective regulation of the pressure inside suction chambers 80, 82, and 84. When gates 86 and 88 are closed, suction is concentrated in the central suction chamber 80. When gates 86 and 88 are open, suction is distributed to the lateral suction chambers 82 and 84 via the central suction chamber 80.

[0096] When the gates 86 and 88 are opened, a pressure drop is achieved when the suction is distributed over a larger area. For narrow-width sheets 1 (e.g., unfolded blanks with a width of less than 1 meter), the suction is preferably concentrated in the central suction chamber 80. Therefore, the suction is greater in the central suction chamber 80 than in the lateral suction chambers 86 and 88. Narrow-width sheets 1 have fewer blocked suction holes than wide-width sheets, thus requiring higher suction. Vacuum adsorption increases with the number of blocked suction holes. By closing the gates 86 and 88 and concentrating the vacuum suction in the central chamber 80, the narrow-width sheets 1 can be better adsorbed onto the upper reverse vacuum conveying device 64. For wider sheets, the suction is applied over the wider width of the sheet 1.

[0097] The opening degree of the gates 86 and 88 can be automatically adjusted by the actuator 87 and controlled by the peripheral control unit 65 or the central control unit 15. For example, a cylinder actuator 87 can be used. The control units 65 and 15 can be configured to calculate and determine the optimal opening degree of the gates 86 and 88 based on the format and / or weight of the sheet 1 and optionally the surface quality. The gates 86 and 88 can then be moved by the actuator 87, which extends in the lateral direction relative to the transport direction D.

[0098] like Figure 7a and 7b As shown, the housing cover 63 of the top reversing vacuum conveyor 64 and the housing cover 65 of the bottom reversing vacuum conveyor 62 preferably overlap by a distance d. This overlap distance d ensures that the position of the sheet 1 is restricted as it is conveyed from the inlet reversing vacuum conveyor 62 to the outlet reversing vacuum conveyor 64. The distance d is chosen to avoid reaction forces / interference between the lower reversing vacuum conveyor 62 and the upper reversing vacuum conveyor 64. During the transition between the inlet reversing vacuum conveyor 62 and the outlet reversing vacuum conveyor 64, the nearest adjacent suction opening 26b of the outlet reversing conveyor 64 is preferably offset relative to the nearest adjacent suction opening 26a of the inlet reversing conveyor 62. Therefore, the distance d can be chosen (i.e., sized such that, in the transport direction D, the first upper suction opening 26b of the upper reversing vacuum conveyor 64 is offset relative to the last lower suction opening 26a of the lower reversing vacuum conveyor 62.

[0099] The reverse conveyor module 60 can be configured to change the adsorption side of the sheet 1 when it is no longer in contact with any printing roller 30. For this purpose, the reverse conveyor module 60 can be provided with an inlet reverse vacuum conveyor 62 of equal or greater length than the sheet 1. This allows the sheet 1 to begin switching to a different adsorption side once it is no longer in contact with the upstream printing roller 30. Therefore, when not in contact with any printing roller 30, a sheet 1 of a certain length will change its traction side.

[0100] However, in a more common implementation, the sheet 1 is longer than the length of the inlet reverse vacuum conveyor 62, and the change on the adsorption side will occur when the sheet 1 is still in the flexographic printing assembly 28 of the upstream printing unit 17.

[0101] To further control the changes on the adsorption side, the inlet reversing vacuum conveyor 62 can be driven in sync with the adjacent vacuum conveyor 66 of the nearest upstream printing unit 17. The speed of the inlet reversing vacuum conveyor 62 is equal to the speed of the vacuum conveyor 66 of the upstream flexographic printing unit 17.

[0102] Similarly, the exit reversing vacuum conveyor 64 can be driven in sync with the vacuum conveyor 68 of the nearest downstream printing unit 17'. This allows the sheet 1 to move at a precise and constant speed in the reversing conveyor module 60 and the adjacent flexographic printing unit 17.

[0103] In another embodiment, the inlet reverse vacuum conveyor 62 and the outlet reverse vacuum conveyor 64 can be connected to the same motor 79, and the speeds of the reverse vacuum conveyors 62 and 64 are equal and limited by the total transport speed obtained through the converter 10. The total transport speed can be calculated and transmitted in real time by the control unit 65.

[0104] The reverse transfer module 60 may further include a guide device 90 configured to control the movement of the front edge 9 of the sheet 1 when the sheet 1 is switched between the inlet reverse vacuum transfer device 62 and the outlet reverse vacuum transfer device 64.

[0105] For this purpose, the first deflector 91 is arranged at an angle relative to the conveying surface 50 of the inlet reversing vacuum conveyor 62, and defines an inlet gap C1 and an outlet gap C2 between itself and the inlet reversing vacuum conveyor 62. The inlet gap C1 is larger than the outlet gap C2, thereby providing a funnel-shaped inlet channel to the outlet vacuum conveyor 64. The first deflector 91 is configured to position the leading edge 9 of the sheet 1 and adhere the sheet 1 to the inlet reversing conveyor 62. The adsorption effect is achieved by the gradual concentration and amplification of the downward vacuum force in the funnel-shaped inlet channel. The first deflector 91 is also configured to position the leading edge 9 of the sheet 1 so that it passes under the outlet vacuum conveyor 64. The funnel-shaped first deflector 91 can also prevent the presence of overlapping sheets 1 by limiting the outlet gap C2, so that only one sheet 1 can pass through at a time.

[0106] The second horizontally arranged deflector 92 is positioned downstream of the first deflector 91 and defines an inlet gap C3 and an outlet gap C4 with respect to the transport surface 50 of the outlet reverse vacuum conveyor 64. The inlet gap C3 and the outlet gap C4 may be equal. The second deflector 92 may be arranged parallel to the outlet reverse vacuum conveyor 64.

[0107] Therefore, the second deflector 92 is configured to confine the sheet substrate 1 at a desired distance C3, C4 below the upper vacuum conveying device 64, so that it is adsorbed and driven by the outlet reverse conveying device 64. This distance C3, C4 ensures that the sheet 1 is lifted and adsorbed onto the upper reverse vacuum conveying device 64 in a controlled and confined manner.

[0108] Without the second deflector 92, there is a risk that the leading edge of sheet 1 may not adhere to the upper reversing vacuum conveyor 64 and may "jump downwards." This would cause the entire sheet to fall vertically.

[0109] When printing on the top surface S1 of the sheet 1, the flexographic printing assembly 28 needs to be arranged differently than when printing on the bottom side S2 of the sheet 1. When printing on the top surface S1 of the sheet 1, the printing cylinder 30 and the doctor blade cavity 36 need to be arranged on top. However, this sometimes makes it difficult to access the printing cylinder 30 to replace the printing plate 31.

[0110] Now for reference Figure 12a and 12b , Figure 12a and 12b A flexographic printing unit 17 is shown, configured to print a sheet substrate 1 on its top side S1. (See diagram.) Figure 12a and 12b As shown, the flexographic printing unit 17 includes a flexographic printing assembly 28 and a flexographic transport unit 66 connected to the vacuum tube 33. The flexographic transport unit 66 can be similar to... Figure 5 The conveying unit 40 shown is configured such that the drive element 42 (such as roller 42) drives the sheet 1 forward in the transport direction D, while the vacuum holes 46 around the roller 42 draw the sheet 1 onto the drive element 42 by suction and participate in keeping the sheet 1 flat.

[0111] The flexographic printing assembly 28 includes a printing cylinder 30, a reverse cylinder 32, an anilox cylinder 34, and a doctor blade cavity 36. When the flexographic printing assembly 28 is configured for top printing, the printing cylinder 30 and the doctor blade cavity 36 are located in the upper portion of the flexographic printing unit 17, above the reverse cylinder 32.

[0112] The flexographic printing unit 17 further includes a structural frame 100, on which the printing assembly 28 is mounted. (As in...) Figure 13a and 13b As best seen in the image, the structural frame 100 includes a fixed frame portion 102 and a movable frame portion 104. Some components of the flexographic printing assembly 28 are connected to the movable frame portion 104 and form a cassette 35, which is vertically movable relative to the fixed frame portion 102.

[0113] The movable frame portion 104 includes a first side bracket 108a and a second side bracket 108b. For example... Figure 14 and 15As best shown, the first side support 108a and the second side support 108b are connected by a plurality of transversely elongated frame members 110. The transverse frame members 110 stabilize the side supports 108a and 108b in order to improve the rigidity of the box 35.

[0114] The flexographic printing assembly 28 includes a printing cylinder 30, an anilox cylinder 34, a reverse cylinder 32, and a doctor blade cavity 36. The printing cylinder is vertically arranged above the reverse cylinder 32 and configured to print on the top side S1 of the sheet 1. The printing cylinder 30, the anilox cylinder 34, and the doctor blade cavity 36 are attached to a movable frame portion 104, and the reverse cylinder 32 is attached to a fixed frame portion 102.

[0115] The first side support 108a and the second side support 108b include openings 107a and 107b configured to receive the ends of the printing cylinder 30 and the anilox cylinder 34. In opening 107c, the reverse roller 32 is mounted to the fixed frame portion 102. Intermediate components (e.g., rolling bearings) can be mounted in the openings and attached to the shafts of the printing cylinder 30, the reverse roller 32, and the anilox cylinder 34.

[0116] The fixed frame portion 102 includes a first side frame portion 109a and a second side frame portion 109b. The first side bracket 108a and the second side bracket 108b are slidably connected to the first side frame portion 109a and the second side frame portion 109b, respectively.

[0117] To provide a sliding connection, a guide rail 112 and a slider 114 can be provided between the movable frame portion 104 and the fixed frame portion 102 to form a sliding connection. For example... Figure 15 As shown, the first and second sliders 114a and 114b can be connected to the first and second side supports 108a and 108b, respectively. The sliders 114a and 114b may include ball bearings arranged in a line to form contact surfaces with guide rails 112a and 112b located on the fixed frame portion 102. Therefore, the first guide rail 112a and the second guide rail 112b can be arranged on the first and second side frame portions 109a and 109b of the fixed frame portion, respectively.

[0118] Preferably, a plurality of sliders 114 can be attached to the side supports 108a, 108b of the housing 35. This enables linear and guided movement of the first and second side supports 108a, 108b. In the illustrated embodiment, one slider 114a, 114b is disposed on each side support 108a, 108b. This further distributes and stabilizes the guidance of the movable frame portion 104. The sliders 114a, 114b can be removably attached to the first side support 108a and the second side support 108b. For example, removable fasteners such as bolts or screws can be used to attach the sliders 114 to the first side support 108a and the second side support 108b. A plurality of sliders 114a, 114b can also be provided to each vertical side of the supports 108a, 108b; for example, there is an upper and a lower slider 114 on each side support 108a, 108b.

[0119] The shifting mechanism 120 is connected to the side supports 108a and 108b and to the fixed frame portion 102. The shifting mechanism 120 includes a motor 122, a first actuator 124a and a second actuator 124b.

[0120] In the illustrated embodiment, actuators 124a and 124b are mechanical actuators. The mechanical actuators 124a and 124b are configured to convert the rotational displacement motion from the motor 122 into linear displacement, and thus displace the movable frame portion 104 in the vertical direction relative to the fixed frame portion 102.

[0121] like Figures 13a to 15 As shown, the first actuator 124a and the second actuator 124b include vertical drive shafts 126a, 126b operably connected to the motor 122, and a first converter 128a and a second converter 128b configured to convert rotational motion into linear displacement.

[0122] Each of the converters 128a and 128b preferably includes bearings 129a and 129b with threaded portions and rotating shafts 130a and 130b. The rotating shafts 130a and 130b are provided with a first end 127 having a threaded portion received in the bearings 129a and 129b. The bearings 129a and 129b are preferably provided with internal threads.

[0123] Motor 122 and vertical drive shafts 126a, 126b transmit rotational motion to rotating shafts 130a, 130b, which in turn cause bearings 129a, 129b to shift vertically. Rotating shafts 129a, 129b can also be referred to as "rotatable shafts". Therefore, when bearings 129a, 129b are fixedly connected to the first and second side supports 108a, 108b of the movable frame portion 104, the housing 35 moves vertically in response to changes in the angular position of rotating shafts 130a, 130b. Preferably, the second ends 137 of the first rotating shaft 130a and the second rotating shaft 130b are supported by connecting flanges 131a, 131b. Connecting flanges 131a, 131b can serve as adjacent surfaces supporting the weight of the housing 35.

[0124] like Figure 14 and 15 As shown in the best embodiment, the same motor 122 is operatively connected to a first actuator 124a and a second actuator 124b arranged on opposite sides of the motor 122.

[0125] For this purpose, a horizontally arranged drive shaft 132 extends horizontally below the housing 35 and is configured to transmit torque from the motor 122 to the second actuator 124b.

[0126] The first end 132a of the drive shaft 132 is connected to the motor 122 via an angle shaft (also called an angle "steering gear") 125a. A second angle shaft 125b is located at the second end 132b of the drive shaft 132 and is connected to a second vertical drive shaft 126b. Therefore, the motor 122 is configured to distribute torque between the first actuator 124a and the second actuator 124b. The first actuator 124a and the second actuator 124b move in unison to change the angular position of the rotating shafts 130a, 130b, thereby changing the vertical position of the housing 35.

[0127] The shifting mechanism 120 provides the advantage of enabling precise shifting of the box 35. Simultaneously, once the rotation of the rotating shafts 130a and 130b stops, the box 35 remains in a fixed position. Additionally, the angle shafts 125a and 125b may include a braking mechanism configured to lock the rotational movement of the vertical drive shafts 126a and 126b, preventing the box 35 from descending when the motor 122 stops.

[0128] Now return to the reference Figure 12a and 12b , Figure 12a and 12b The vertical movement of box 35 between operating position A and maintenance position B is shown. Operating position A (see...) Figure 12aCorresponding to the printing position, the printing cylinder 30 and the reverse cylinder 32 are spaced apart at a distance suitable for printing the sheet 1. In the inspection position B (see...) Figure 12b Compared to printing position A, printing cylinder 30 is further apart from reverse cylinder 32.

[0129] like Figure 12a As shown, the doctor blade cavity 36 is positioned at or below the machine operator's eye level and restricts access to the printing cylinder 30. Figure 12b As shown, by moving the box 35 upwards when changing the printing plate 31, the printing cylinder 30 can be positioned in a variable position and according to the operator's preference. Ideally, the access position is set so that the operator can change the printing plate 31 without bending over. In this way, the operator has full visibility and access to the printing cylinder 30.

[0130] In this implementation, the operating position A and the maintenance position B can be stored in the peripheral memory 67 of the flexographic printing module 16 (see [link]). Figure 2 The operating position A depends on the sheet thickness and the printed circuit board thickness and can vary between different jobs. The maintenance position B can be adjusted based on the operator's height and preferences. Preferably, the control unit 15 can retrieve the operating position A and maintenance position B from the memory 67 or 27 when it receives a command from the operator. Therefore, maintenance position B can be automatically retrieved by the control unit 15 when it receives a login script.

[0131] For example, when the operator provides input to the machine interface 11 to select maintenance position B, the control unit can automatically activate the shifting mechanism 120, causing the printing roller 30 to move to the desired position. Similarly, once the printing plate 31 has been replaced, and once the control unit 15 has received the command to resume operation, the shifting mechanism 120 can move the printing roller 30 to the operating position.

[0132] In this implementation, the control unit 15 can automatically retrieve the setting of maintenance location B based on the login data of the operator logging into the operator interface.

[0133] Additionally, memory 67 or 27 may further include position data defining other maintenance locations. The position data includes operational information enabling control unit 15 to actuate motor 122 and move movable frame portion 104 to multiple predetermined positions. For example, memory 67, 27 may further include position data for anilox roller replacement locations. The cartridge 35 in the anilox roller replacement location may preferably be positioned vertically below the replacement printing plate.

Claims

1. A reverse transfer module (60) for a converter having a printing module (16), the printing module (16) comprising at least one first printing unit (17) having a top printing roller (30) arranged to print on the top side (S1) of a sheet (1) and at least one second printing unit (17') having a bottom printing roller (30) arranged to print on the bottom side (S2) of the sheet. A reverse transfer module is configured to transport a sheet (1) between at least one first printing unit and at least one second printing unit, wherein the reverse transfer module includes an inlet reverse vacuum transfer device (62) and an outlet reverse vacuum transfer device (64), each configured to contact and transport different sides of the sheet, thereby configuring the reverse transfer module to change the adsorption and transport sides of the sheet, and the reverse transfer module further includes: A first deflector (91), arranged at an angle and defining an inlet gap (C1) and an outlet gap (C2) with respect to the inlet reversing vacuum conveying device (62), wherein the inlet gap is larger than the outlet gap, thereby providing a funnel-shaped inlet channel leading to the outlet reversing vacuum conveying device, and A second deflector (92) is arranged horizontally and defines an inlet gap (C3) and an outlet gap (C4) with respect to the outlet reverse vacuum conveying device (64), wherein the second deflector is parallel to the outlet reverse vacuum conveying device.

2. The reverse transfer module according to claim 1, wherein the printing module (16) is a flexographic printing module, wherein the first printing unit (17) includes a top printing roller (30) arranged to print on the top side (S1) of the sheet, and the second printing unit (17') has a bottom printing roller arranged to print on the bottom side (S2) of the sheet.

3. The reverse transfer module according to claim 1, further comprising a pivotally movable locking member (72) connected to the housing (61) of the reverse transfer module.

4. The reverse transfer module according to claim 3, wherein the pivotally movable locking member (72) is configured to engage with a corresponding mating geometry in the printing module (16) to mechanically connect the housing (61) of the reverse transfer module (60) to the housing of the first printing unit (17).

5. The reverse transfer module according to any one of claims 1 to 4, wherein the inlet reverse vacuum transfer device is connected to the first vacuum generator, and the outlet reverse vacuum transfer device is connected to the second vacuum generator.

6. The reversing conveying module according to any one of claims 1 to 4, wherein the vacuum suction of the inlet reversing vacuum conveying device configured to apply suction to the top side of the sheet is higher than the vacuum suction of the outlet reversing vacuum conveying device configured to apply suction to the bottom side of the sheet.

7. The reverse transfer module according to any one of claims 1 to 4, further comprising a structural frame, wherein the inlet reverse vacuum transfer device and the outlet reverse vacuum transfer device are mounted on the same structural frame (70).

8. The reverse transmission module according to any one of claims 1 to 4, wherein the reverse transmission module is provided with a shifting device (13) so that the reverse transmission module can be horizontally shifted.

9. The reversing conveying module according to any one of claims 1 to 4, wherein the housing of the inlet reversing vacuum conveying device configured to apply suction to the top side of the sheet includes a separate suction compartment connected to the inlet vacuum generator.

10. The reverse conveying module according to claim 9, wherein the suction compartment is defined by an inner wall extending in the transport direction and is arranged such that a centrally located suction compartment (80) is provided between a first lateral suction compartment (82) and a second lateral suction compartment (84).

11. The reverse transfer module according to claim 10, wherein the inner wall is configured as a movable gate, wherein the suction from the inlet vacuum generator can be distributed to the first lateral suction compartment (82) and the second lateral suction compartment (84) by opening the gate.

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