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(11) | EP 4 442 623 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | SHEET SYNCHRONIZING MACHINE |
| (57) The sheet synchronization machine comprises an acceleration station (2), where the
sheets (7) are received and accelerated; and a synchronization station (3), downstream
of the acceleration station (2), which receives the sheets (7) from the acceleration
station (2) and synchronously feeds them to a downstream processing station (4). It permits to provide a sheet synchronizing machine that enables sheet processing, such as printing, die-cutting and/or stacking, from an uncycled input stream. |
Object of the invention
[0001] The present invention relates to a sheet synchronizing machine, in particular, for synchronizing a discrete flow of sheets for further processing, such as printing, die-cutting and/or stacking, on the same line, in particular of printed cardboard sheets, coming from a digital printer.
Background to the invention
[0002] During the manufacture of cartons or similar boxes, the cardboard sheets that form them are subjected to different processes, such as printing, die-cutting, and stacking for transport.
[0003] The printing is done to print on the sheets the designs, markings, or information that you want to be visible during the final use of the box. This printing can be done by digital printing or by flexography.
[0004] In die-cutting, folding lines and cut-outs are formed to form the final box according to its design and characteristics.
[0005] Stacking is carried out to transport a plurality of sheets together, the sheets being loose one on top of the other, each sheet being able to contain different printed and/or die-cut patterns joined together by means of dots, in the form of a mosaic. In this way, each sheet can contain different boxes.
[0006] These printing, die-cutting and stacking operations are usually carried out on separate machines and the sheets must be transported from one machine to the next, with the cost that this represents, due to the means of handling the sheets, the space they occupy and the time that must be invested in transporting the sheets between the different machines.
[0007] To minimize this transport, it is common to install a die-cutting machine downstream of a flexographic printer. However, this means that the two machines must be synchronized, i.e., the printing and die-cutting cylinders must have a common register.
[0008] In conventional flexographic printing presses, the sheets are cycled, i.e., they are always the same distance apart. Normally this distance is the subtraction of the sheet length from the length of the impression cylinder. In digital printers, on the other hand, the distance between sheets can always be the same regardless of the length of the printed sheet.
[0009] Therefore, if you want to perform a cycled operation after printing the sheet with a digital printer, it is necessary to cycle the sheet flow. For example, to process the sheet with a rotary or flatbed die cutter after printing it with a digital printer, it is necessary to synchronize the sheets to match the die cut cycle.
[0010] Currently, digital printing lines cannot perform operations such as die-cutting on the same line but must be moved to a separate die-cutting line, with the associated logistics and loss of efficiency.
Description of the invention
[0011] An objective of the present invention is to provide a sheet synchronizing machine that allows a processing of sheets, such as printing, die-cutting and/or stacking, from an uncycled input stream.
[0012] With the sheet synchronizing machine of the invention, the above-mentioned disadvantages are solved, presenting other advantages that will be described below.
[0013] The sheet synchronizing machine according to the present invention is described in claim 1, and the dependent claims include additional features that are optional.
[0014] The dynamic independent sheet synchronizing machine comprises an acceleration station and a synchronizing station. The acceleration station makes it possible to establish, from a minimum or even zero sheet gap, a sufficient gap between the sheets for further processing in the synchronizing station.
[0015] The acceleration station comprises separate drive elements, e.g., wheel or belt trains, which can vary their speed independently of each other.
[0016] These displacement elements in contact with the sheet synchronize their speeds sequentially. Thus, when a sheet has released a displacement element, all the other displacement elements in contact with that sheet can accelerate together, while the initial displacement element remains at the previous speed, as it is in contact with the next sheet and the latter is not yet accelerated.
[0017] At the synchronization station, which, for example, comprises belts with stops, the appropriate and precise register is set for feeding the sheet to the next processing station (die-cutter, printer, etc.).
[0018] Thanks to the space created in the acceleration station, the stop can enter between two sheets and push the relevant sheet from the rear. Advantageously, the stops contact the sheet from the rear, but do not immobilize the sheet on the belt, so that the sheet can move in the same plane, but in a direction perpendicular to the belt feed to allow adjustment of the lateral register before feeding it into the next processing station.
[0019] The correction of the lateral register of the sheets is carried out, for example, by means of side plates that move alternately between an open and a closed position. The latter position determines the exact position of the sheet in the direction perpendicular to the feed direction.
[0020] In this way, the longitudinal and lateral registers are corrected before the sheet is fed to the next processing station, thus obtaining a perfect synchronization of the sheet flow, regardless of the characteristics of this flow at the inlet, such as: initial separation between sheets, sheet dimensions, longitudinal and lateral registers, etc.
[0021] Furthermore, the system is robust and can tolerate slight variations or deviations from the nominal values of these quantities without affecting the next processing station, which will always receive them perfectly positioned and synchronized.
[0022] According to a preferred embodiment, the independent dynamic sheet synchronizing machine further comprises a rotary die cutting station and a stacking and stack removal station downstream of the synchronization station, so that die cutting and/or stacking of sheets can be performed with a single processing line.
[0023] The rotary die cutting station comprises:
- a first cylinder,
- a second cylinder, and
- a complementary cylinder,
[0024] Preferably, the first cylinder and the second cylinder are rotatable about a central axis, which is equidistant from both cylinders.
[0025] Advantageously, the stacking and stack removal station comprises supports for supporting a second stack of sheets on top of a first stack of sheets, allowing more than one stack of sheets to be stacked and ejected continuously without waiting.
[0026] Said supports are advantageously movable between a standby position and a use position, in which use position the sheets are stacked on the supports, and said supports are also movable between an extended position and a retracted position.
[0027] In addition, the stacking and removal station also preferably comprises wheels that move the sheets into a stacking position, pushers that push the sheets away from the wheels, and a base that is movable, on which a stack of sheets is placed.
[0028] The sheet synchronizing machine according to the present invention may also comprise:
- a receiving station, where pre-printed sheets are received, where rejected sheets can be removed, or to remove a sample for inspection of print quality or sheet processing; and
- a vibration station equipped with vibrating belts at the exit of the punching station.
Brief description of the drawings
[0029] For a better understanding of what has been explained above, some drawings are included in which, schematically and only by way of a non-limiting example, a practical case of embodiment is represented.
Figure 1 is an elevation view of the sheet synchronizing machine according to the present invention;
Figure 2 is an elevation view of the acceleration and synchronization stations of the sheet synchronization machine according to the present invention;
Figure 3 is a plan view of the acceleration and synchronization stations of the sheet synchronization machine according to the present invention;
Figures 4 to 11 are plan and elevation views of the stacking and synchronizing stations of the sheet synchronizing machine according to the present invention, showing the synchronizing process;
Figure 12 is a schematic elevation view showing the speeds of the sheets during their synchronization by the synchronizing machine according to the present invention;
Figures 11 to 17 are elevation views of the stacking station of the die cutting and/or sheet stacking machine according to the present invention, showing the sheet ejection process; and
Figures 18 to 23 are elevation views of the stacking station of the die cutting and/or sheet stacking machine according to the present invention, showing the continuous stacking process.
Description of a preferred embodiment
[0030] Figure 1 is an elevation view of the sheet synchronizing machine according to a preferred embodiment of the present invention.
[0031] According to this figure, from left to right, which is the direction of transport of the sheets, the machine according to the embodiment depicted comprises a receiving station 1, where already printed sheets, e.g., cardboard sheets printed by a digital printer, are received.
[0032] In this receiving station 1, the sheets are checked for compliance with the quality requirements, so that the sheets that do not meet the quality requirements are deposited in a container 11 via a trap door 12. In addition, this receiving station 11 also includes a sample tray 13, where one or more films can be deposited.
[0033] Next, the machine according to the present invention comprises an acceleration station 2, in which a gap is created between the sheets, and subsequently the sheets reach a synchronization station 3.
[0034] As can be seen in figures 2 and 3, the acceleration station 2 comprises a plurality of displacement elements 21, such as wheel trains or belts, and the synchronization station 3 comprises belts 31 with stops 32 and positioning plates 33.
[0035] The operation of acceleration station 2 and synchronization station 3 is explained with the help of figures 4 to 12.
[0036] Figure 4 shows acceleration stations 2 and synchronization stations 3 with sheets 7 located therein and cylinders 41, 43 of a die station 4 which will be described later.
[0037] In this figure 4, the first sheet, on the right in the figure, has not yet reached the end of the belt 31.
[0038] Figure 5 shows that the sheets 7 have advanced slightly, with the first sheet being inserted between the cylinders 41, 43, and the stop 32 being placed between the two sheets between the acceleration station 2 and the synchronization station 3. The plan view in this figure shows the difference in separation between the sheets 7.
[0039] In figure 6, the stop 32 is located between the two sheets 7 but is not yet in contact with either of them.
[0040] In figure 7, the stop 32 contacts the sheet 7 on the back of the belt 31 and synchronization begins.
[0041] In figure 8, the sheet 7 is pushed by the stop 32 for synchronization with the rear station, in this case the die cutting station 4, and the space between sheets is increasing, as can be seen in the plan view of this figure and in figure 9. As can be seen, the sheets 7 are advancing along the acceleration station 2 and synchronization station 3.
[0042] In figure 10, the front sheet, on the right in the figure, is synchronized with the die-cutting station 4, and the rear sheets 7 are already separated at the desired distance.
[0043] In figure 11, the sheets 7 continue to advance and the synchronization of the next sheet 7 is started, repeating the process.
[0044] To facilitate the understanding of the displacement of the sheets 7, figure 12 shows the velocities of the displacement elements 21 of the acceleration station 2, namely the initial velocity, v0, the velocity, v, during synchronization and the acceleration, a.
[0045] The machine according to the embodiment shown here comprises a die-cutting station 4, in which the die-cutting of the sheet can be carried out. It should be noted that, although the sheets pass through this die-cutting station 4, they can, if desired, pass through it without being die-cut, for subsequent stacking, as will be explained below.
[0046] The die-cutting station 4 comprises a first cylinder 41, a second cylinder 42 and a complementary cylinder 43, whereby the first and second cylinders 41, 42 can be placed in an in-use position or in a standby position.
[0047] In the position shown in figure 1, the first cylinder 41 is in the use position and performs the die cutting together with the complementary cylinder 43, passing the sheet to be die cut between them. On the other hand, the second cylinder 42 is in the standby position and does not act during die-cutting, being below the first cylinder 41 and separated from it in figure 1.
[0048] To change from the use position to the standby position and vice versa, the first cylinder 41 and the second cylinder 42 are rotatable with respect to a central axis 44, which is located equidistant with respect to both cylinders 41, 42, as can be seen in figure 1.
[0049] In this way, when a die is to be changed, this die is placed in the second cylinder 42, and is moved from the standby position to the working position by rotating both cylinders 41, 42 around the central axis 44.
[0050] With this double-cylinder system 41, 42, the die-cutting operation only has to be interrupted briefly to change the position of the cylinders 41, 42 from the use position to the standby position, and vice versa.
[0051] This die-cutting station 4 also comprises a waste removal chute 44, through which the waste material from the die-cutting process is removed.
[0052] Next, the machine according to the embodiment shown comprises a vibration station 5, comprising vibrating belts 51, on which the sheets coming out of the die cutting station 4 are cleaned.
[0053] Finally, the machine according to the embodiment shown comprises a stacking and ejection station 6, where the sheets 7 are ejected, either individually or grouped in stacks or bundles. The ejection process is explained with the aid of figures 13 to 17.
[0054] As can be seen in Figure 13, the stacking and ejection station 6 comprises wheels 61, which transport the sheet 7 that has left the vibration station 5. When the sheet 7 reaches the desired position, it stops (Figure 14) and then the sheet 7 is separated from the wheels 61 by pushers 62, which can be moved between a waiting position and a pushing position, in which movement they push the sheet 7 downwards, as can be seen in Figure 15.
[0055] Once the sheet 7 is separated from the wheels 61, the sheet 7 falls onto a stack of sheets 7 that have been previously placed, as shown in figure 16, or onto a base or conveyor belt 63 if it is the first sheet.
[0056] At the same time, the pushers 62 return to their standby position, i.e., they rise according to the figures, to act on the next sheet 7, as shown in figure 17.
[0057] Once the stack of sheets 7 has been formed, it can be ejected from the stacking and ejection station 6 by means of a conventional ejection element, not shown in the figures. Preferably, this is done by pushing the stack of sheets 7 from its shorter side, if the sheets are rectangular.
[0058] According to the embodiment shown, the ejection would be forward, i.e., according to an axis perpendicular to the figures.
[0059] The stacking and ejection process can advantageously be carried out continuously and without interruption, as can be seen in figures 18 to 23, which will be described below.
[0060] The transport of the sheet 7 is also carried out by the wheels 61, and once in the desired position, the sheet 7 is separated from the wheels 61 by means of the pushers 62, as explained above.
[0061] When the stack of sheets 7 is sufficiently high, it must be ejected, as explained above, but in order not to stop the stacking and ejection process, the stacking and ejection station 6 comprises supports 64, which are preferably in the form of rods.
[0062] These supports 64 serve to support a sheet 7 or a stack of sheets on a lower stack of sheets, so that an upper stack can be formed on a lower stack, the two stacks being separated from each other.
[0063] The supports 64 are movable between a standby position, shown in Figures 13 to 17, and a use position, shown in Figure 18, in which it is lowered relative to the standby position, and between an extended position, in which it may be in the use position or in the standby position, and a retracted or withdrawn position, which is explained later.
[0064] In figure 18, the base 63 is lowered to eject the stack of sheets on it, and the supports 64 are in the position of use.
[0065] Next, sheets 7 are placed on the supports 64, as shown in figure 19. The positioning of the sheets 7 is carried out in the same way as explained above for the formation of a stack of sheets.
[0066] Once the base 63 has been lowered, the stack of sheets 7 is removed, in a direction perpendicular to figure 20, and at the same time a new sheet 7 is stacked on top of the upper stack.
[0067] Once the lower stack has been ejected, the base 63 is raised again, as shown in figure 21, until the base 63 is at the same height as the supports 64, at which point the supports 64 retract, i.e., move in a direction perpendicular to the figure, so that the stack of sheets 7 is supported on the base 63, as shown in figure 22.
[0068] In this way, a lower stack of sheets is created, placed on the base 63 (figure 23), and the process starts again, placing the supports 64 in the initial position to form a new stack of sheets.
[0069] Although reference has been made to a specific embodiment of the invention, it is obvious to a person skilled in the art that the synchronizing machine described is susceptible to numerous variations and modifications, and that all the details mentioned can be replaced by technically equivalent ones, without departing from the scope of protection defined by the appended claims.
1. A sheet synchronizing machine, characterized in that it comprises:
- an acceleration station (2), where the sheets (7) are received and accelerated; and
- a synchronization station (3) downstream of the acceleration station (2), which receives the sheets (7) from the acceleration station (2) and synchronously feeds them to a downstream processing station (4).
2. Sheet synchronizing machine according to claim 1, wherein the acceleration station
(2) comprises a plurality of displacement elements (21).
3. Sheet synchronizing machine according to claim 2, wherein the displacement elements
(21) are wheel or belt trains.
4. Sheet synchronizing machine according to any one of the preceding claims, wherein
the synchronizing station (3) comprises one or more belts (31), wherein the belt or
belts (31) comprise stops (32).
5. Sheet synchronizing machine according to any one of the preceding claims, wherein
the synchronizing station (3) comprises positioning plates (33).
6. Sheet synchronizing machine according to claims 4 and 5, wherein the positioning plates
(33) are laterally displaceable with respect to the one or more belts (31).
7. Sheet synchronizing machine according to any one of the preceding claims, wherein
the downstream processing station is a die-cutting station (4).
8. Sheet synchronizing machine according to claim 7, wherein the die cutting station
(4) comprises:
- a first cylinder (41),
- a second cylinder (42), and
- a complementary cylinder (43),
wherein the first and second cylinders (41, 42) are movable between a use position and a standby position.9. Sheet synchronizing machine according to claim 8, wherein the first cylinder (41)
and the second cylinder (42) are rotatable with respect to a central axis (44), which
is located equidistant with respect to both cylinders (41, 42).
10. Sheet synchronizing machine according to any one of the preceding claims, also comprising
a stacking and ejection station (6).
11. Sheet synchronizing machine according to claim 10, wherein the stacking and ejection
station (6) comprises supports (64) for supporting a second stack of sheets (7) on
a first stack of sheets (7), said supports (64) being movable between a standby position
and a use position, in which use position the sheets (7) are stacked on the supports
(64), and/or said supports (64) are also movable between an extended position and
a retracted position.
12. Sheet synchronizing machine according to any one of claims 10 or 11, wherein the stacking
and ejection station (6) also comprises wheels (61) that move the sheets (7) into
a stacking position, pushers (62) that push the sheets (7) away from the wheels (61),
and/or a base (63) that is movable, on which a stack of sheets (7) is placed.
13. Sheet synchronizing machine according to any one of the preceding claims, also comprising
a receiving station (1), where pre-printed sheets (7) are received.
14. Sheet synchronizing machine according to any one of the preceding claims, also comprising
a vibration station (5) provided with vibrating belts (51) at the outlet of the die
cutting station (4).