Transformation machine with inverted transition module

Abstract

The present invention relates to a converting machine provided with a reversing transfer module (60). The converting machine comprises a printing module (16) including a first printing unit (17) arranged to print on a top side (S1) of a sheet (1) and a second printing unit (17') arranged to print on a bottom side (S2) of the sheet. The reversing transfer module comprises first and second reversing vacuum transfer sections (62, 64) arranged between the first and second printing units and configured to change the bonding and transport side of the sheet.

Description

[Technical field]

[0001] The present invention relates to a converting machine that is suitable for producing paper or cardboard boxes having printed patterns on both the inside and outside surfaces. [Background technology]

[0002] In the packaging industry, boxes are typically produced from corrugated paper or paperboard sheet substrates. There are two main types of boxes: folding slotted boxes (sometimes also referred to as "folded boxes") and flatpack boxes. Folding slotted boxes are folded and glued together in a converting machine, while flatpack boxes are provided from the converting machine as flat sheets that may then be folded and closed (e.g., with adhesive tape) when provided with their final contents.

[0003] The present invention relates to a converting machine with a printing unit. Such a converting machine can be configured as a rotary die-cutting machine suitable for producing printed flatpack boxes or as a flexo-folder-gluer converting machine for producing foldable slotted boxes. Taking the rotary die-cutting machine as an example, it comprises a series of modules including a feeder module, a flexo printing module, a die-cutting machine module and typically a stacker module.

[0004] Corrugated or paperboard boxes are typically provided with a printed pattern on their exterior surface. In a standard exterior printing process, a flexographic printing cylinder in a converting machine is typically positioned below the sheet and configured to print on the bottom side of the sheet, which may then represent the exterior surface of the box.

[0005] Sometimes it is desirable to print on the inside of the box as well, so that further information or decorative patterns can be provided on the inside of the box. To print on both the outside and inside of the box, the flexographic printing module must further include at least one additional flexographic printing unit having a printing cylinder arranged to print on the upper side of the sheet.

[0006] The sheet needs to be transported top-side when the sheet is to be printed from the bottom up, and conversely, if the sheet is to be printed on the top side, the sheet needs to be transported bottom-side.

[0007] The transport and adhesion of the sheet is achieved in part using transport elements and vacuum suction units configured to apply suction to the bottom and top sides of the sheet in an alternating manner, this arrangement driving the sheet and maintaining it in a desired vertical position relative to the print cylinder inside the converting machine.

[0008] For perfecting printing processes, it is necessary to shift / switch the side of the sheet transport between the top and bottom flexographic cylinders. However, this change in transport and adhesion causes the sheet to change direction vertically. This can cause disruptions that lead to undesirable register shifts and further misalignment of downstream located printing, cutting and creasing operations. Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above mentioned problems, it is an object of the present invention to provide a converting machine with a smooth and controlled transition of sheets between the top and bottom printing units. [Means for solving the problem]

[0010] The object of the present invention is solved by a conversion machine according to claim 1.

[0011] According to a first aspect of the present invention there is provided a converting machine for printing a sheet and transforming it into a packaging element for a box, the converting machine comprising: a printing module comprising a first printing unit arranged to print on a top side of a sheet and a second printing unit arranged to print on a bottom side of the sheet, - a conveying system configured to convey a sheet through a converting machine along a conveying path in a conveying direction, the conveying system comprising a first transfer unit configured to contact and convey the sheet at a bottom side of the sheet and a second transfer unit configured to contact and convey the sheet at a top side of the sheet, the transfer unit comprising said conveying system comprising a drive element configured to move the sheet forward in the conveying direction and a vacuum opening arranged to adhere the sheet to the drive element; The converting machine further includes an inverting transfer module disposed between the first printing unit and the second printing unit, the inverting transfer module including an inlet inverting vacuum transfer section and an outlet inverting vacuum transfer section, each configured to contact and transport a different side of the sheet, whereby the inverting transfer module is configured to change the bonding and transport side of the sheet.

[0012] The invention is based on the realization that a controlled change of the transport side of the sheet can be achieved with a dedicated module configured to control the conveyance of the sheet. Thus, the reversing transfer module displaces the sheet vertically at the same time as the transport side is changed.

[0013] The packaging element may be a flatpack box, a folding slotted box or a folding box. The packaging element is preferably made from corrugated paper or paperboard.

[0014] In one embodiment, the printing module is a flexographic printing module, with the first printing unit having a top printing cylinder arranged to print on the top side of the sheet and the second printing unit having a bottom printing cylinder arranged to print on the bottom side of the sheet.

[0015] In one embodiment, the printing module is an offset printing module, with a first printing unit having a top printing cylinder arranged to print on the top side of the sheet and a second printing unit having a bottom printing cylinder arranged to print on the bottom side of the sheet.

[0016] 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.

[0017] In one embodiment, the converting machine is in a rotary die-cutting machine configuration. In another embodiment, the converting machine is in a flexo-folder-gluer configuration.

[0018] In one embodiment, the first flexographic printing unit is disposed upstream of the second flexographic printing unit in the conveying direction, and the inlet inverting vacuum transfer is configured to apply suction to a bottom side of the sheet, i.e., to adhere the bottom side of the sheet to the drive elements of the inlet inverting transfer.

[0019] In one embodiment, the inlet reverse vacuum transition is driven in unison with the adjacent transport unit of the nearest upstream positioned printing unit, the speed of the inlet reverse vacuum transition being equal to the speed of the transport unit of the nearest upstream positioned printing unit.

[0020] In one embodiment, the exit reverse vacuum transition is driven in unison with the transport unit of the nearest downstream positioned printing unit, the speed of the exit reverse vacuum transition being equal to the speed of the transport of the nearest downstream positioned flexographic printing unit.

[0021] In one embodiment, the converting machine further comprises a die-cutting module positioned downstream of the printing module in the conveying direction.

[0022] In one embodiment, the conversion machine comprises a movable part and a fixed part, and the inverting translation module is arranged as a transition element between the movable part and the fixed part, the movable part comprises a module displaceable on a floor surface, and the fixed part comprises a module fixedly mounted on the floor surface.

[0023] In one embodiment, the reversing transfer module is provided with a displacement means to allow horizontal displacement of the reversing transfer module relative to the flexographic printing unit. The displacement means can be a wheel, a roller or a slide rail.

[0024] According to another aspect of the present invention there is provided an inverting transfer module for a converting machine having a flexographic printing module comprising at least one first flexographic printing unit having a top printing cylinder arranged to print a top side of a sheet, and at least one second flexographic printing unit having a bottom printing cylinder arranged to print a bottom side of the sheet, The invert transfer module is configured to transport the sheet between at least one first flexographic printing unit and at least one second flexographic printing unit, the invert transfer module including an inlet invert vacuum transfer section and an outlet invert vacuum transfer section, each configured to contact and transport a different side of the sheet, whereby the invert transfer module is configured to change the bonding and transport side of the sheet.

[0025] In one embodiment, the printing module is a flexographic printing module, with the first printing unit having a top printing cylinder arranged to print on the top side of the sheet and the second printing unit having a bottom printing cylinder arranged to print on the bottom side of the sheet.

[0026] In one embodiment, the inverting transition module further comprises a pivotable locking portion connected to the housing of the inverting transition module, the pivotable locking portion may be configured to engage a corresponding mating feature in the printing module, such as to mechanically connect the housing of the inverting transition module with a housing of the printing unit.

[0027] In one embodiment, the reverse transition module further comprises a first deflector disposed at an angle and defining an entry clearance and an exit clearance with the inlet reverse vacuum transition, the entry clearance being greater than the exit clearance such that a funnel-shaped entry passage to the outlet reverse vacuum transition is provided.

[0028] In one embodiment, the inverting transition module includes a second horizontally disposed deflector that defines an entry clearance and an exit clearance with the exit inverting transition section, the deflector being parallel to the exit inverting vacuum transition section.

[0029] In one embodiment, the inlet reverse vacuum transition is connected to a first vacuum generator and the outlet reverse vacuum transition is connected to a second vacuum generator.

[0030] In one embodiment, the vacuum suction force for an inverting vacuum transfer section configured to apply suction to the top side of the sheet is higher than the vacuum suction force for an inverting vacuum transfer section configured to apply suction to the bottom side of the sheet.

[0031] In one embodiment, the inverting transfer module further comprises a structural frame, and the upper and lower inverting vacuum transfer sections are mounted on the same structural frame, the structural frame being separate from the flexographic printing module.

[0032] In one embodiment, the inverting transition module is provided with displacement means allowing horizontal displacement of the inverting transition module. The displacement means may be wheels, rollers or guide rails.

[0033] In one embodiment, the housing of the inverting vacuum transition configured to apply suction to the top side of the sheet includes a separate suction compartment connected to an upper vacuum generator.

[0034] The compartment may be defined by an inner wall extending in the conveying direction and is arranged to provide a centrally located suction compartment, the centrally located suction compartment being disposed between the first lateral suction compartment and the second lateral suction compartment.

[0035] In one embodiment, the inner wall is configured as a movable shutter, and suction force from the vacuum generator can be distributed to the first lateral suction box and the second lateral suction box by opening the shutter.

[0036] Further advantages and features will become apparent from the following description of illustrative embodiments of the invention and from the accompanying drawings in which like features are designated with like reference numerals and in which: [Brief description of the drawings]

[0037] [Figure 1a] FIG. 2 shows the flatpack box before assembly. [Figure 1b] FIG. 1 shows the flatpack box after assembly. [Figure 1c] FIG. 2 is a schematic diagram of a stack of sheet substrates. [Diagram 2] FIG. 1 illustrates an example of a converting machine in the configuration of a rotary punching machine. [Diagram 3] FIG. 1 is a schematic perspective view of a flexographic printing module. [Figure 4] FIG. 1 is a schematic perspective view of a flexographic printing assembly. [Diagram 5] 1 is a schematic diagram of an embodiment of a vacuum transition. [Figure 6] 1 is a schematic cross-sectional view of an inverted transition module according to an embodiment of the present invention. [Figure 7a] FIG. 2 is a detailed cross-sectional view of an inverted transition module according to an embodiment of the present invention. [Figure 7b] FIG. 13 is a detailed view of the transition between the bottom vacuum inversion transition and the top vacuum inversion transition. [Figure 8a] FIG. 1 is a schematic cross-sectional view of a locking arrangement between an inverting transfer module and a flexographic printing unit. [Figure 8b]FIG. 1 is a schematic cross-sectional view of a locking arrangement between an inverting transfer module and a flexographic printing unit. [Figure 9] FIG. 7b is a schematic perspective view of the inverted transition module of FIG. 7a from the inlet side. [Figure 10] FIG. 2 is a schematic perspective view of the reverse transfer module from the outlet side. [Figure 11] FIG. 11 is a schematic cross-sectional view of the inverted transition module of FIGS. 9 and 10. [Figure 12a] FIG. 2 is a schematic cross-sectional view of a flexographic printing unit for topside printing according to an embodiment of the invention with the printing assembly in the printing position. [Figure 12b] FIG. 2 is a schematic cross-sectional view of a flexographic printing unit for topside printing according to an embodiment of the present invention with the printing assembly in a service position. [Figure 13a] FIG. 12b is a schematic side view of a structural frame of the flexographic printing unit of FIG. 12a. [Figure 13b] FIG. 12c is a schematic side view of the structural frame of the flexographic printing unit of FIG. 12b. [Figure 14] FIG. 12c is a schematic front view of the structural frame from FIGS. 12a and 12b. [Figure 15] FIG. 15 is a schematic perspective view of the structural frame of FIG. 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Reference is now made to Figures 1a and 1b, which show an example of a flat-pack box 1'' and a box 1' resulting from the flat-pack box 1'' after folding. As can be seen, the flat-pack box 1' comprises creased edges 2 to enable folding and cut outer edges 4 to give the box 1' its overall shape, and may further comprise cut-outs 5 (e.g. for handles). The flat-pack box 1'' is derived from a sheet substrate 1 as shown in Figure 1c. The sheet substrate 1 is a square or rectangular sheet of corrugated paper or paperboard.

[0039] The flatpack box 1'' of Figure 1b is produced in a converting machine 10 as shown in Figure 2. In the entry position of the converting machine 10, raw paperboard or corrugated paper sheet substrate 1 is placed in a feeder module 14 and conveyed in a conveying direction D to receive a series of operations which print, cut and score the sheet substrate 1.

[0040] The converting machine 10 shown in Figure 2 is in a rotary die-cutting machine configuration. However, in another embodiment not shown, the converting machine 10 can be in a flexo-folder-gluer configuration. The converting machine 10 of Figure 2 includes a number of different modules or workstations that perform different processing steps on the sheet substrate 1 as it is conveyed through the converting machine 10.

[0041] The converting machine 10 may include, from an inlet of the converting machine 10 and downstream along a conveying direction D, a pre-feeder 12, a feeder module 14, a flexographic printing module 16 including at least one flexographic printing unit 17, a die-cutter module 18, a bundle stacker 20, and a palletizer-breaker module 22. A main operator interface 11 may also be provided near the converting machine 10.

[0042] The sheet substrate 1 may be in the form of an intermediate blank provided with a number of flatpack boxes 1'' arranged side by side before the palletizer and breaker module 22. Figure 1b shows the shape of the intermediate blank obtained before the palletizer-breaker module 22. A number of crease lines 2 and cut lines 4 are provided on the face of the intermediate blank. Perforation lines 3 may be provided and may be torn in the palletizer-breaker module 22 in order to separate a first blank from a second blank.

[0043] Paper or corrugated board substrate in the form of sheets 1 is introduced into the converting machine 10 by a feeder 14, which feeds the sheets 1 one by one at predetermined intervals into the converting machine 10. To allow for a continuous supply of sheets 1, a stack of sheets is placed in the feeder 14.

[0044] A flexographic printing module 16 can be positioned after the feeder module 14 and is configured to print on one side of the sheet 1. Typically and in currently commercially available converting machines, the sheet 1 is printed on a different side, which will be the outside of the box.

[0045] As best seen in FIG. 3, the flexographic printing module 16 can include at least one flexographic printing unit 17. Preferably, the flexographic printing module 16 includes multiple flexographic printing units 17a, 17b through 17n, such as to enable printing of different colors. For example, the flexographic printing unit 17 can use custom inks or a CMYK color model to achieve color printing with cyan, magenta, yellow, and base (black) inks. The flexographic printing unit 17 includes an outer housing 24 and a structural frame 100 on which a flexographic printing assembly 28 (shown in FIG. 4) is mounted.

[0046] An exemplary bottom printing flexographic assembly 28 for the flexographic printing unit 17 as known in the art is shown in FIG. 4. The flexographic printing assembly 28 includes a printing cylinder 30 having a mounting bracket 38 to which a printing plate 31 can be attached. The printing plate 31 is provided with a printing die configured to print a particular motif on the sheet 1. An anilox cylinder 34 is disposed near the printing cylinder 30 and configured to aspirate and transfer ink from a liquid supply device (such as a doctor blade chamber 36) to the printing plate 31.

[0047] Anvil 32 (also referred to as counter cylinder) is positioned next to impression cylinder 30 and is configured to back / press sheet 1 against impression cylinder 30 and ensure that the motif is transferred to sheet 1 .

[0048] As best seen in Figures 2 and 5, the converting machine 10 further comprises a transport system configured to transport the sheet 1 along a transport path P through the converting machine 10 in a transport direction D. The transport direction D is defined from the inlet to the outlet of the converting machine 10. The transport path P may therefore extend from the feeder module 14 in the direction of the die-cutting machine module 18 and in the direction of the delivery table. The transport system comprises drive elements such as endless belt conveyors and rollers that transport the sheet 1 through the converting machine 10. The transport system may comprise a number of separate transport segments referred to as transfer sections 40. In particular, the transfer section 40 comprises a series of transport units 66, 68 positioned within the flexographic printing units 17, 17'. The transport units 66, 68 may be in the form of vacuum transport units 66, 68. The transport system further comprises vacuum transport units arranged between the different workstations.

[0049] The transition section 40 includes a drive element 42, such as a drive roller 42, and a number of suction openings 46 disposed around the drive roller 42. The suction openings 46 are configured to hold the sheet 1 securely against the drive roller 42. Alternatively, a conveyor belt can be used in place of the drive roller 42.

[0050] The transfer section 40 further comprises a transport surface 50, which may be a smooth metal surface. The drive roller 42 is positioned opposite the side of the printing cylinder 30, whereby the drive roller 42 can transport the sheet 1 on its "dry side", which is opposite the side currently being printed by the printing plate 31. As a result, the side of transport of the sheet 1 needs to be changed in the converting machine 10 when the sheet 1 is to be printed on both the bottom side S2 and the top side S1.

[0051] Reference is now made to Figure 6, which illustrates a cross-sectional view of a printing module 16 according to an embodiment of the present invention. As shown, the printing module 16 may be in the form of a flexographic printing module 16.

[0052] The flexographic printing module 16 includes a first flexographic printing section 16a and a second flexographic printing section 16b.

[0053] The first flexographic printing section 16a comprises at least one flexographic printing unit 17 in a top-surface printing configuration. The second flexographic printing section 16b comprises at least one flexographic printing unit 17' in a bottom-surface printing configuration.

[0054] The first flexographic printing section 16a is configured to print, i.e., on a top side S1 of the sheet 1, and the second flexographic printing section 16b is configured to print on a bottom side S2 of the sheet 1. The top side S1 may represent the inside of a box in this case, and the bottom side S2 of the sheet may represent the outside of the box.

[0055] The first flexographic printing section 16a may comprise one or more flexographic printing units 17, for example four, 17a, 17b, 17c, 17d, to allow for the use of different inks. Similarly, the second flexographic printing section 16b may comprise one or more flexographic printing units 17'.

[0056] The invert transfer module 60 is disposed 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.

[0057] In case of double-sided printing, the transport system comprises a first group of transfer stations 40 configured to contact and transport the sheet 1 at its top side S1 and a second group of transfer stations 40 configured to transport the sheet 1 at its bottom side S2. The flexographic printing module 16 comprises both of these two groups of transfer stations 40 to transport the sheet 1 at its side opposite to the side to be printed. To this effect, the first group of transfer stations comprises a first transport unit 66 in the first flexographic printing unit 17, configured to contact and transport the sheet 1 at its bottom side S2. Similarly, the second flexographic printing unit 17' comprises a second transport unit 68 configured to transport the sheet 1 at its top side S1. The transport units 66, 68 are typically vacuum transport units and are configured to adhere the sheet 1 to the drive roller 42.

[0058] Even if the invention is described and illustrated with the top printing unit 17 arranged in front of the bottom printing unit 17', it is also possible to have a converting machine 10 in which the bottom printing unit 17' is arranged in front of the top printing unit 17 in the conveying direction D. In such a case, the illustrated invert transfer module 60 is arranged in an invert / mirror manner.

[0059] However, locating the top printing section 16a before the bottom printing section 16b may provide better precision at the die-cutting module 18. Because the sheet 1 is transported adhered to its top side S1 when it arrives at the die-cutting module 18, the sheet 1 may also be positioned closer to the top-mounted rotary die-cutting tool, thereby providing better transport and more precise positioning of the sheet 1 at the die-cutting module 18.

[0060] Alternatively, in an embodiment 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 a top side S1 of the sheet 1 and a second printing unit configured to print on a bottom side S2 of the sheet 1.

[0061] In another embodiment, the printing module 16 may comprise a first printing unit in the form of an inkjet printing unit configured to print on a top side S1 of the sheet 1 and a flexographic printing unit configured to print on a bottom side S2 of the sheet 1.

[0062] The inverting transfer module 60 comprises a bottom inverting vacuum transfer section 62 configured to contact the bottom side S2 of the sheet 1 and a top inverting vacuum transfer section 64 configured to contact the top side S1 of the sheet 1. The bottom inverting vacuum transfer section 62 and the top inverting vacuum transfer section 64 of the inverting transfer module 60 allow a change of conveying side of the sheet 1. Thus, the inverting transfer module 60 changes the adhesive side of the sheet 1 from a transfer unit 66 positioned upstream of the first printing section 16a to a transfer unit 68 positioned downstream of the second printing section 16b. In the illustrated embodiment, in the conveying direction D, the bottom inverting vacuum transfer section 62 is configured as an entrance vacuum transfer section and the top inverting vacuum transfer section 64 is configured as an exit vacuum transfer section.

[0063] As shown in Figures 7a and 7b, the inlet inverting vacuum transition section 62 and the outlet inverting vacuum transition section 64 are mounted to a structural frame 70. The vertical distance d2 between the inlet inverting vacuum transition section 62 and the outlet inverting vacuum transition section 64 in the inverting transition module 60 is selected to allow a typical maximum thickness of sheet 1 to pass through the clearance between the inlet inverting vacuum transition section 62 and the outlet inverting vacuum transition section 64. Typically, this clearance distance d2 may be approximately 10 mm, corresponding to a typical maximum cardboard thickness.

[0064] As shown in Figures 7a, 7b, 8a and 8b, the inverting transfer module 60 may further comprise at least one locking mechanism 71 for mechanically connecting the inverting transfer module 60 to the nearest upstream flexographic printing unit 17. The locking mechanism 71 comprises a movable locking part 72 attached to a lever 73 and a piston actuator 74. The locking part 72 is positioned on a first end 73a of the lever 73, while a second end 73b of the lever is fixedly but rotatably mounted on the housing 61 of the inverting transfer module 60 and defines a rotation axis A of the lever 73. The piston actuator 74 is connected to the first end 73a of the lever 73. The piston actuator 74 can be actuated such that the locking part 72 located on the first end 73a is moved in a circular path and vertically. The structural frame 100 of the printing unit 17 comprises a corresponding mating shape for the locking part 72 so that the locking of the inverting transfer module 60 and the structural frame 100 of the printing unit 17 can be achieved.

[0065] The piston actuated lever 73 allows, i.e., forcing the structural frames 70, 100 or housings 61, 19 of the inverting transfer module 60 and the printing unit 17 into contact with one another. The piston actuator 74 can thus be actuated until a stop is sensed, thereby indicating that the housings 61, 19 are in contact with one another.

[0066] The inverting transition module 60 may include two locking mechanisms 71 positioned on each side of the inverting transition module 60 to achieve a uniform connection.

[0067] In an embodiment not shown, a similar locking mechanism 71 may be positioned downstream of the inverting transfer module 60 and may be actuated to lock the inverting transfer module 60 to the nearest downstream positioned flexographic printing unit 17' in the second flexographic printing section 16b. This locking mechanism may be advantageously used when the nearest downstream positioned flexographic printing unit 17' of the second flexographic printing section 16b is movable (i.e. displaceable on the floor surface).

[0068] The locking mechanism 71 allows the reversing transfer module 60 to be disengaged from the flexographic printing units 17, 17'. If the flexographic printing units 17, 17 are movable (i.e. displaceable on the floor), the flexographic printing units 17, 17 can be moved (in the conveying direction D) after disengagement from the reversing transfer module 60 or from the adjacent flexographic printing unit 17. If the reversing transfer module 60 is movable, it can also be displaced. Such an actuation may be necessary to gain access to the printing plate 31 on the flexographic printing cylinder 30 or for general inspection interruptions.

[0069] As seen in FIG. 6, the converting machine 10 may comprise a movable part 20a and a fixed part 20b, and the inverting and transitioning module 60 may be arranged as a transition element between the movable part 20a and the fixed part 20b. The movable part 20a may be configured to include modules from the feeder 14 in the first flexographic printing section 16a to the last flexographic printing unit 17. The fixed part 20b may be configured to include the inverting and transitioning module 60 and the flexographic printing unit 17' in the second flexographic printing section 16b. The modules of the movable part 20a may have rollers or wheels 13 for displacement on the floor surface. Alternatively, instead of wheels, the modules of the movable part 20a may be slidably mounted on the floor surface by means of slide rail connections. Optionally, the inverting and transitioning module 60 may be provided with wheels 13 for displacement on the floor surface.

[0070] The inlet reverse vacuum transition 62 and the outlet reverse vacuum transition 64 are connected to at least one vacuum source 76a, 76b through a vacuum duct 33. In the illustrated embodiment, the inlet reverse vacuum transition 62 may be connected to a first vacuum generator 76a and the outlet reverse vacuum transition 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 force between the inlet reverse vacuum transition 62 and the outlet reverse vacuum transition 64.

[0071] The vacuum generators 76a, 76b can be configured to provide a variable vacuum force. In particular, the converting machine 10 can be configured to receive different set points so that the vacuum force and area of ​​the vacuum force can be modified. The set points can be modified depending on the size (i.e., sheet area), weight, and surface quality of the sheet 1. With respect to surface quality, typically a smooth surface will adhere better to the vacuum openings 46 than an uneven surface. The vacuum generators 76a, 76b or generator 76 can provide a variable vacuum force in response to variable rpm set points.

[0072] 10 and 11, the housing 61 of the top inverted vacuum transition 64 can include separate suction compartments 80, 82, 84 connected to the vacuum generator 76b. The interior walls 86, 88 extending in the conveying direction D are arranged such that a centrally located suction compartment 80 is provided and is disposed between the first lateral suction compartment 82 and the second lateral suction compartment 84.

[0073] The central suction compartment 80 is provided with separation walls 86, 88 relative to the first and second lateral suction compartments 82, 84. The separation walls 86, 88 are provided as movable shutters 86, 88 and are configured to provide a variable opening degree. The shutters 86, 88 may be pivotally movable.

[0074] The shutters 86, 88 control the position of the suction force. The central suction compartment 80 can be directly connected to the vacuum generator 76b. The shutters 86, 88 are opened to distribute negative pressure to the first and second lateral suction compartments 82, 84. Thus, a vacuum is created in the lateral suction compartments 82, 84 when the shutters 86, 88 of the central suction compartment 80 are opened.

[0075] The shutters 86, 88 allow selective adjustment of the pressure inside the suction compartments 80, 82, 84. The suction force is concentrated in the central suction compartment 80 when the shutters 86, 88 are closed. The suction force is distributed through the central suction compartment 80 to the lateral suction compartments 82, 84 when the shutters 86, 88 are open.

[0076] When the shutters 86, 88 are opened, the pressure drop is achieved while the suction force is distributed over a wider area. In the case of a narrow sheet 1 (e.g. an unfolded blank less than one meter wide), the suction force is preferably concentrated in the central suction section 80. Thus, the suction force is greater in the central suction section 80 than in the lateral suction sections 86, 88. A narrow sheet 1 requires a higher suction force since it blocks fewer suction openings than a wider sheet. The degree of vacuum adhesion is increased as a function of the increasing number of blocked suction openings. By closing the shutters 86, 88 and concentrating the vacuum suction force in the central section 80, a narrow sheet 1 can be better adhered to the top inverted vacuum transition 64. The wider the width, the more suction force is applied over a larger width of the sheet 1.

[0077] The opening degree of the shutters 86, 88 is adjusted automatically by actuators 87 and can be controlled from the peripheral control unit 65 or from the central control unit 15. For example, pneumatic cylinder actuators 87 can be used. The control units 65, 15 can be configured to calculate and determine the optimal opening degree of the shutters 86, 88 depending on the format and / or weight and optionally the surface quality of the sheet 1. The shutters 86, 88 can then be moved with the actuators 87 extending transversely to the conveying direction D.

[0078] As shown in Figures 7A and 7B, the housing side plate 63 of the top inverted vacuum transition section 64 and the housing side plate 65 of the bottom inverted vacuum transition section 62 preferably overlap by a distance d. The overlapping distance d ensures a restriction on the position of the sheet 1 as it is transferred from the inverted vacuum transition section 62 to the outlet inverted vacuum transition section 64. The distance d is selected to avoid reaction / interference between the lower inverted vacuum transition section 62 and the upper inverted vacuum transition section 64. At the transition between the inverted vacuum transition section 62 and the outlet inverted vacuum transition section 64, the nearest adjacent suction opening 26b of the outlet inverted transition section 64 is preferably offset with respect to the nearest adjacent suction opening 26a of the inverted vacuum transition section 62. Thus, the distance d can be selected (i.e., dimensioned) such that the first upper suction opening 26b of the top inverted vacuum transition section 64 is offset with respect to the last lower suction opening 26a of the lower inverted vacuum transition section 62 in the conveying direction D.

[0079] The inverting transfer module 60 can be configured to change the adhesive side on the sheet 1 when the sheet 1 is not in contact with any of the print cylinders 30. To this effect, the inverting transfer module 60 can be provided with an inlet inverting vacuum transfer section 62 having a length equal to or greater than the length of the sheet 1, whereby the sheet 1 can only begin to transition to a different adhesive side when it is no longer in contact with the upstream positioned print cylinder 30. Thus, a certain length of the sheet 1 will change tow side when it is not in contact with any of the print cylinders 30.

[0080] However, in a more typical embodiment, the sheet 1 will be longer than the length of the inlet reversal vacuum transfer section 62 and the change in adhesive side will occur while the sheet 1 is still within the flexographic printing assembly 28 of the upstream positioned printing unit 17.

[0081] The inlet reverse vacuum transfer section 62 can be driven in coordination with the adjacent vacuum transport unit 66 of the nearest upstream positioned printing unit 17 to further control the change in the glue side. The speed of the inlet reverse vacuum transfer section 62 is the same as the speed of the vacuum transport unit 66 of the upstream positioned flexographic printing unit 17.

[0082] Similarly, the exit reverse vacuum transfer section 64 can be driven in unison with the vacuum transport unit 68 of the nearest downstream positioned printing unit 17', thereby allowing for accurate and constant velocity of the sheet 1 through the reverse transfer module 60 and the adjacent flexographic printing unit 17.

[0083] In another embodiment, the inlet reverse vacuum transition section 62 and the outlet reverse vacuum transition section 64 can be connected to the same motor 79 and the speed of the reverse vacuum transition sections 62, 64 is equal and is determined by the overall conveying speed recovered through the conversion machine 10. The overall conveying speed can be calculated and communicated in real time by the control unit 65.

[0084] The inverting transition module 60 further comprises a guide arrangement 90 configured to control movement of the front leading edge 9 of the sheet 1 as the sheet transitions between the entrance inverting vacuum transition section 62 and the exit inverting vacuum transition section 64 .

[0085] To this effect, the first deflector 91 is disposed at an angle to the conveying plane 50 of the inlet inverting vacuum transition 62 and defines an entry clearance C1 and an exit clearance C2 with the inlet inverting vacuum transition 62. The entry clearance C1 is greater than the exit clearance C2 so that a funnel-shaped entry path to the exit vacuum transition 64 is provided. The first deflector 91 is configured to position the sheet leading edge 9 to bond the sheet 1 flat against the inlet inverting transition 62. This bonding effect is achieved by the progressive concentration and amplification of the vacuum force down in the funnel-shaped entry path. The first deflector 91 is also configured to position the front leading edge 9 of the sheet 1 so that the sheet passes under the exit vacuum transition 64. The funnel-shaped first deflector 91 can also prevent the presence of overlapping sheets 1 by limiting the exit clearance C2 so that only one sheet 1 can pass at a time.

[0086] A second horizontally disposed deflector 92 is disposed downstream of the first deflector 91 and defines an entry clearance C3 and an exit clearance C4 with the conveying surface 50 of the exit reverse vacuum transition 64. The entry clearance C3 and the exit clearance C4 may be equal. The second deflector 92 may be disposed parallel to the exit reverse vacuum transition 64.

[0087] Thus, the second deflector 92 is configured to confine the sheet substrate 1 at a desired distance C3, C4 below the upper vacuum transition section 64 so that it may be adhered to and driven by the exit inverted transition section 64. This distance C3, C4 ensures that the sheet 1 is lifted up to and adhered to the upper inverted vacuum transition section 64 in a controlled and confined manner.

[0088] Without the second deflector 92, the leading edge of sheet 1 would not adhere to the upper inverting vacuum transition 64 and would risk "diving under," causing the entire sheet to drop vertically.

[0089] The flexographic printing assembly 28 needs to be positioned differently when printing on the top side S1 of the sheet 1 than when printing is done on the bottom side S2 of the sheet 1. The printing cylinder 30 and doctor blade chamber 36 need to be positioned on the top side when printing on the top side S1 of the sheet 1. However, this can make it difficult to access the printing cylinder 30 to change the printing plate 31.

[0090] Reference is now made to Figures 12a and 12b, which show a flexographic printing unit 17 configured to print a sheet substrate 1 on its upper side S1. As shown in Figures 12a and 12b, the flexographic printing unit 17 comprises a flexographic printing assembly 28 and a flexographic transport unit 66 connected to a vacuum duct 33. The flexographic transport unit 66 may be configured similarly to the transport unit 40 shown in Figure 5, whereby a driving element 42, such as a roller 42, drives the sheet 1 forward in a conveying direction D, while a vacuum opening 46 around the roller 42 is responsible for the driving element 42 to adhere the sheet 1 by suction and keep it flat.

[0091] The flexographic printing assembly 28 includes a printing cylinder 30, a counter cylinder 32, an anilox cylinder 34, and a doctor blade chamber 36. The flexographic printing assembly 28 is configured for topside printing, such that the printing cylinder 30 and doctor blade chamber 36 are positioned above the counter cylinder 32 at the top of the flexographic printing unit 17.

[0092] The flexographic printing unit 17 further comprises a structural frame 100 on which the printing assembly 28 is mounted. As best seen in Figures 13a and 13b, the structural frame 100 comprises a fixed frame part 102 and a movable frame part 104. Some components of the flexographic printing assembly 28 form a cassette 35 which is connected to the movable frame part 104 and is vertically movable relative to the fixed frame part 102.

[0093] The movable frame portion 104 includes a first side bracket 108a and a second side bracket 108b. As best seen in Figures 14 and 15, the first side bracket 108a and the second side bracket 108b are connected by a plurality of transverse and elongated frame components 110. The transverse frame components 110 stabilize the side brackets 108a, 108b to improve the rigidity of the cassette 35.

[0094] The flexographic printing assembly 28 comprises a printing cylinder 30, an anilox cylinder, a counter cylinder 32, and a doctor blade chamber 36. The printing cylinder is disposed vertically above the counter cylinder 32 and is configured to print on the upper side S1 of the sheet 1. The printing cylinder 30, the anilox cylinder 34 and the doctor blade chamber 36 are mounted to a movable frame part 104, and the counter cylinder 32 is mounted to a fixed frame part 102.

[0095] The first side bracket 108a and the second side bracket 108b are provided with openings 107a, 107b configured to receive the ends of the print cylinder 30 and the anilox cylinder 34. The counter cylinder 32 is mounted to the fixed frame part 102 at the opening 107c. Intermediate parts such as rolling bearings can be mounted in the openings and attached to the shafts of the print cylinder 30, the counter cylinder 32 and the anilox cylinder 34.

[0096] The fixed frame 102 portion includes a first side frame portion 109a and a second side frame portion 109b. A first side bracket 108a and a second side bracket 108b are slidably connected to the first side frame portion 109a and the second side frame portion 109b, respectively.

[0097] The guide rail 112 and the sliding block 114 can be provided between the movable frame part 104 and the fixed frame part 102 to form a sliding connection to provide a sliding connection. As shown in FIG. 15, the first and second sliding blocks 114a, 114b can be connected to the first and second side brackets 108a, 108b, respectively. The sliding blocks 114a, 114b can include ball bearings arranged in a row to include contact surfaces for the guide rails 112a, 112b positioned on the fixed frame part 102. Thus, the first guide rail 112a and the second guide rail 112b can be arranged on the first and second side frame parts 109a, 109b of the fixed frame part, respectively.

[0098] Preferably, a plurality of sliding blocks 114 can be attached to the side brackets 108a, 108b of the cassette 35, thereby allowing linear and guided movement of both the first and second side brackets 108a, 108b. In the illustrated embodiment, one sliding block 114a, 114b is provided on each side bracket 108a, 108b, which also further distributes and stabilizes the guidance of the movable frame portion 104. The sliding blocks 114a, 114b can be removably attached to the first and second side brackets 108a, 108b. For example, removable fasteners such as bolts and screws can be used to attach the sliding blocks 114 to the first and second side brackets 108a, 108b. Similarly, multiple sliding blocks 114a, 114b may be provided on each vertical side of the brackets 108a, 108b, for example, one upper sliding block 114 and one lower sliding block 114 on each side bracket 108a, 108b.

[0099] The displacement mechanism 120 is connected to the side brackets 108a, 108b and the fixed frame portion 102. The displacement mechanism 120 includes a motor 122, a first actuator 124a, and a second actuator 124b.

[0100] In the illustrated embodiment, the actuators 124a, 124b are mechanical actuators configured to convert rotational displacement motion from the motor 122 into linear displacement, thus displacing the moveable frame portion 104 vertically and relative to the fixed frame portion 102.

[0101] As shown in Figures 13 to 15, the first and second actuators 124a, 124b include vertical drive shafts 126a, 126b operatively connected to the motor 122 and first and second transducers 128a, 128b configured to convert rotational motion into linear displacement.

[0102] Each of the transducers 128a, 128b preferably comprises a bearing 129a, 129b having a threaded portion, and a rotating shaft 130a, 130b. The rotating shaft 130a, 130b is provided with a first end 127 having a threaded portion that is received in the bearing 129a, 129b. The bearings 129a, 129b are preferably provided with female threads.

[0103] The motor 122 and the vertical drive shafts 126a, 126b transmit the rotational motion to the rotating shafts 130a, 130b, which in turn displace the bearings 129a, 129b vertically. The rotating shafts 130a, 130b can also be referred to as "rotatable shafts". As a result, the cassette 35 moves vertically in response to changes in the angular position of the rotating shafts 130a, 130b, since the bearings 129a, 129b are fixedly connected to the first and second side brackets 108a, 108b of the movable frame part 104. Preferably, the second ends 137 of the first rotating shaft 130a and the second rotating shaft 130b are supported by the connecting flanges 131a, 131b. The connecting flanges 131a, 131b can act as abutment surfaces on which the weight of the cassette 35 is supported.

[0104] As best seen in FIGS. 14 and 15, the same motor 122 can be operatively connected to a first actuator 124a and a second actuator 124b disposed on opposite sides of the motor 122.

[0105] To this effect, a horizontally disposed transmission shaft 132 extends horizontally below the cassette 35 and is configured to transmit torque from the motor 122 to the second actuator 124b.

[0106] A first end 132a of the transmission shaft 132 is connected to the motor 122 through an angle shaft 125a (also referred to as an "angle divider"). A second angle shaft 125b is located at a second end 132b of the transmission shaft 132, which connects to a second vertical drive shaft 126b. The motor 122 is thus configured to distribute torque between the first actuator 124a and the second actuator 124b. The first and second actuators 124a, 124b move in unison to modify the angular positions of the rotation shafts 130a, 130b to change the vertical position of the cassette 35.

[0107] The displacement mechanism 120 of the present invention provides the advantage that a precise displacement can be achieved for the cassette 35. At the same time, the cassette 35 is maintained in a fixed position when the rotation of the rotary shafts 130a, 130b is stopped. In addition to this, the angle shafts 125a, 125b can be equipped with a braking mechanism configured to lock the rotational movement of the vertical drive shafts 126a, 126b so that the cassette 35 cannot be lowered when the motor 122 is stopped.

[0108] Reference is now made to Figures 12a and 12b, which show the vertical movement of the cassette 35 between an operating position A and an inspection position B. Operating position A (see Figure 12a) corresponds to the printing position, in which the printing cylinder 30 and the counter cylinder 32 are spaced apart at a distance suitable for printing the sheet 1. In inspection position B (see Figure 12b), the printing cylinder 30 is spaced further from the counter cylinder 32 than in printing position A.

[0109] As seen in Fig. 12a, the doctor blade chamber 36 is positioned at or below the eye level of the machine operator, with limited access to the printing cylinder 30. By moving the cassette 35 upwards when changing the printing plate 31, as shown in Fig. 12b, the printing cylinder 30 can be positioned in variable positions and according to the operator's preference. Ideally, the service 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.

[0110] In one embodiment, the operating position A and the inspection position B can be stored in the peripheral memory 67 (see FIG. 2) of the flexographic printing module 16 (or in the centralized memory 27 of the converting machine 10). The operating position A may vary between different jobs depending on the sheet thickness and printing plate thickness. The inspection 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 the inspection position B from the memory 67 or 27 upon command from the operator. Thus, the inspection position B can be automatically retrieved by the control unit 15 upon receipt of the login script.

[0111] For example, when an operator provides an input to the machine interface 11 selecting inspection position B, the control unit can automatically actuate the displacement mechanism 120 to move the printing cylinder 30 to the desired position. Similarly, once the printing plate 31 has been replaced, the displacement mechanism 120 can move the printing cylinder 30 to the operating position once a command to resume operation is received by the control unit 15.

[0112] In one embodiment, the control unit 15 may automatically retrieve the set point for service position B based on operator login data into the operator interface.

[0113] In addition, the memory 67 or 27 may further comprise position data defining other service positions. The position data comprises actuation information enabling the control unit 15 to actuate the motor 122 to displace the movable frame part 104 to a number of predefined positions. For example, the memory 67, 27 may further comprise position data for an anilox change position. In the anilox change position the cassette 35 may preferably be positioned vertically lower than in the position for changing printing plates.

Claims

1. A converting machine (10) for printing a sheet (1) and transforming it into a packaging element for a box (1''), a printing module (16) comprising a first printing unit (17) arranged to print on a top side (S1) of a sheet and a second printing unit (17') arranged to print on a bottom side (S2) of said sheet; a conveying system configured to convey the sheet in a conveying direction (D) along a conveying path (P) through the converting machine, the conveying system comprising a first transport unit (66) configured to contact and convey the sheet at the bottom side (S2) of the sheet and a second transport unit (68) configured to contact and convey the sheet at the top side (S1) of the sheet, the transport unit comprising a drive element (42) configured to move the sheet forward in the conveying direction and a vacuum opening (46) arranged to suck the sheet against the drive element, the first transport unit (66) being arranged in the first printing unit (17) and the second transport unit (68) being arranged in the second printing unit (17'), the converting machine further comprises an inverting transfer module (60) arranged between the first printing unit (17) and the second printing unit (17'), the inverting transfer module comprising an inlet inverting vacuum transfer section (62) and an outlet inverting vacuum transfer section (64), the inverting transfer module (60) being arranged between the first transport unit (66) and the second transport unit (68), each of the inlet inverting vacuum transfer section (62) and the outlet inverting vacuum transfer section (64) being configured to contact and transport a different side of the sheet, whereby the inverting transfer module is configured to change the side of attraction and transport of the sheet. A transformation machine (10).

2. said printing module (16) being a flexographic printing module; said first printing unit (17) comprises a top printing cylinder (30) arranged to print a top side (S1) of the sheet, and said second printing unit (17') has a bottom printing cylinder arranged to print a bottom side (S2) of the sheet, 2. The conversion machine according to claim 1.

3. the first printing unit is arranged upstream of the second printing unit in the conveying direction (D), the inlet inversion vacuum transition is configured to apply suction to the bottom side of the sheet; A conversion machine according to claim 1 or 2.

4. a die-cutting module (18) positioned downstream of the printing module in the conveying direction, A transformation machine according to any one of claims 1 to 3.

5. said inlet reverse vacuum transition section (62) being driven in unison with the adjacent transport unit (66) of the nearest upstream positioned printing unit (17), whereby the speed of said inlet reverse vacuum transition section (62) is equal to the speed of said transport unit (66) of said nearest upstream positioned printing unit (17); A transformation machine according to any one of claims 1 to 4.

6. said outlet reverse vacuum transition section (64) being driven in unison with said second transport unit (68) of the nearest downstream positioned printing unit (17'), whereby the speed of said outlet reverse vacuum transition section is equal to the speed of said second transport unit (68) of said nearest downstream positioned printing unit (17'); A transformation machine according to any one of claims 1 to 5.

7. The conversion machine comprises a movable part (20a) and a fixed part (20b), The inverted transition module is arranged as a transition element between the movable part and the fixed part. A transformation machine according to any one of claims 1 to 6.

8. the inverting and transferring module is provided with a displacement means for enabling horizontal displacement of the inverting and transferring module relative to the printing units (17, 17'); A transformation machine according to any one of claims 1 to 7.

9. the inverted transfer module further comprises a pivotable locking portion (72) configured to engage with a corresponding mating feature in a printing module (17, 17'), such as to mechanically connect a housing of the inverted transfer module (60) with a housing of the printing unit (17, 17'); A transformation machine according to any one of claims 1 to 8.

10. the reverse transition module further comprises a first deflector having a surface facing the inlet reverse vacuum transition section (62), the surface being angled to define an entry clearance (C1) and an exit clearance (C2) with the inlet reverse vacuum transition section (62); the entry clearance is greater than the exit clearance such that a funnel-shaped entry path to the exit reverse vacuum transition is provided; A transformation machine according to any one of claims 1 to 9.

11. the inverting transition module further comprises a second horizontally disposed deflector defining an entry clearance (C3) and an exit clearance (C4) with the exit inverting vacuum transition section (64); the deflector is parallel to the exit reverse vacuum transition; 11. The conversion machine according to claim 10.

12. the inlet reverse vacuum transition is connected to a first vacuum generator and the outlet reverse vacuum transition is connected to a second vacuum generator; A transformation machine according to any one of claims 1 to 11.

13. a vacuum suction force of the outlet inversion vacuum transfer section (64) configured to apply suction to the top side of the sheet is greater than a vacuum suction force of the inlet inversion vacuum transfer section (62) configured to apply suction to the bottom side of the sheet; 13. A conversion machine as claimed in claim 12.

14. Further comprising a structural frame (70); The inlet reverse vacuum transition section (62) and the outlet reverse vacuum transition section (64) are mounted on the same structural frame (70). A transformation machine according to any one of claims 1 to 13.

15. a housing of the outlet inversion vacuum transition (64) configured to apply suction to the top side of the sheet includes a separate suction section connected to an upper vacuum generator; A transformation machine according to any one of claims 1 to 14.

16. the suction compartments are defined by inner walls extending in the conveying direction and are arranged to provide a centrally located suction compartment (80), the centrally located suction compartment being disposed between a first lateral suction compartment (82) and a second lateral suction compartment (84); 16. A conversion machine according to claim 15.

17. The inner wall is configured as a movable shutter, Suction force from a vacuum generator is distributed to the first lateral suction section (82) and the second lateral suction section (84) by opening the shutter.

17. The conversion machine according to claim 16.

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