Printing unit and method for adjusting a printing unit

Abstract

The invention relates to a printing unit of a printing press or a rotary die cutter for printing sheets and / or webs with an anilox roller (2) transferring ink to the printing cylinder (4), wherein the anilox roller (2) is assigned as an infeed device (3, 40) which changes the axial distance to the printing cylinder (4) and which has two actuators working intermittently against one another.

Description

[0001] Printing unit and method for adjusting a printing unit

[0002] Description

[0003] The present invention relates to printing units according to the preamble of claim 1 and a method for adjusting a printing unit according to the preamble of claim 8.

[0004] Printing units with an anilox roller are known for printing webs or sheets of substrate, especially corrugated board. The anilox roller serves to wet the printing cylinder with a predetermined amount of printing ink. During production breaks, and especially during setup, the anilox roller is moved to a rest or maintenance position. The distance between the anilox roller and the printing cylinder is sufficiently large to allow for changes to the printing plate, for example.

[0005] To allow the anilox roller to switch between an operating position and a maintenance position, it is mounted in a pivoting frame on well-known flexographic printing units, such as those from Hycorr. The frame rests on pneumatic bellows on either side of the anilox roller, with its side opposite the pivot bearings.

[0006] In the operating position, the bellows are pressurized with compressed air and raise the pivoting frame against a mechanical stop. To adjust the contact between the anilox roller and the printing cylinder, the stop is designed as an eccentric. In the maintenance position, the bellows are vented, lowering the anilox roller.

[0007] Such pivoting devices are robust and have proven themselves many times over in the continuous operation of such printing units. However, the time required to switch between the production position and the maintenance position of the anilox roller is a disadvantage. Simply venting the bellows is too slow to lower the anilox roller sufficiently in the event of missing single sheets, for example, due to singulation errors, to prevent ink transfer to the printing roller in the product gap and to ensure timely ink application for the subsequent sheet.

[0008] The object of the invention is therefore to provide a printing unit of the type described above and a method for its operation, which overcome at least one of the disadvantages indicated and do not place high demands on the technical design and costs.

[0009] The invention solves the problem by a device having the features of patent claim 1 and by a method having the features of patent claim 8. Advantageous developments of the invention are characterized by the features specified in the dependent claims.

[0010] The anilox roller is accommodated in a first adjustment device, which is capable of changing the center distance between the anilox roller and the associated printing cylinder. To prevent damage, the center distance is limited to a predetermined minimum by a stop. Furthermore, the stop enables very high repeatability when adjusting the anilox roller to the specified minimum distance.

[0011] According to the invention, a second feed device acts on the stop in such a way that the minimum center distance achievable by the first feed device can be changed by the second feed device.

[0012] In an advantageous embodiment, the first feed device comprises at least one pivoting arm in which the anilox roller is accommodated. Particularly advantageous are two parallel, opposing pivoting arms in which the anilox roller is mounted on both sides. The second feed device is arranged between the arm and the associated stop in such a way that the first feed device and the second feed device can counteract each other.

[0013] Advantageously, the first feed device comprises a pneumatic bellows as the first feed drive, and the second feed device comprises a double-acting pneumatic lifting cylinder as the second feed drive. The bellows is suitable for dampening vibrations of the anilox roller relative to the printing cylinder. The lifting cylinder is designed to exert a greater force than the bellows, so that, depending on the wiring of the lifting cylinder, the anilox roller can be moved away from the printing cylinder against the force of the bellows. This allows a predetermined intermediate position of the anilox roller to be reached, in which no ink is transferred to the printing cylinder and the relatively far-spaced maintenance position does not need to be assumed.

[0014] For a faster transition from the operating position to this intermediate position, the lifting cylinder is equipped with quick-release valves. Furthermore, during this position change, the bellows can be depressurized, at least briefly, to reach the intermediate position even sooner.

[0015] The present invention is not limited to positioning an anilox roller accommodated in the feed device relative to the associated printing cylinder. Instead, any other roller involved in the printing process can also be adjusted by the described feed device.

[0016] The invention will now be explained using an exemplary embodiment with reference to the figures, to which reference is made for all details not mentioned in detail in the description. The figures show:

[0017] Fig. 1 is a simplified view of an anilox roller with a feed device in a printing unit;

[0018] Fig. 2 schematic representations of the delivery device in three states;

[0019] Fig. 3 Switching states of the actuators when changing the anilox roller from the operating position to the intermediate position.

[0020] In a machine frame 1 shown in Fig. 1, a printing cylinder 4 is mounted in the side walls 11 of the machine frame 1, arranged on either side of a transport path 200. The printing cylinder 4 is rotatable about its axis and driven by a drive of a known type (not shown). The printing cylinder 4 is arranged transversely such that it is tangent to the plane defined by the printing substrate.

[0021] In addition, an anilox roller 2 is housed in the machine frame 1. This roller interacts with the printing cylinder 4 during printing and transfers the printing medium to the printing cylinder 4 in a predetermined quantity and distribution. For this purpose, the anilox roller 2 is arranged parallel to the printing cylinder 4.

[0022] The anilox roller 2 is mounted at a variable distance from the printing cylinder 4. A first feed device 3 is provided for this purpose. This comprises two symmetrically constructed units, each of which is arranged on one of the frame walls 11. One of these two units is explained below as an example:

[0023] A pivot arm 31 is arranged parallel to the frame wall 11. It is mounted in the side wall 11 by a pivot bearing 30 of a known type. The pivot axis 301 of the arm 31 defined thereby runs parallel to the anilox roller 2. Thus, the arm 31 pivots parallel to the sagittal plane of the printing unit. The anilox roller 2 is mounted in the pivot arm 31 so as to be rotatable about its axis 201.

[0024] The pivot arm 31 is arranged essentially horizontally. It rests at its end opposite the pivot bearing 30 against a cross member 12 of the machine frame 1.

[0025] A bellows 32 is arranged as an actuator between the cross member 12 and the pivot arm 31. This bellows sits on the cross member 12 and is rigidly connected to the pivot arm 31 via a holder 35. The bellows 32 is supplied with compressed air via a line 37. It is suitable for dampening oscillations or vibrations of the anilox roller. The compressed air line 37 comprises a controllable valve of a known type (not shown). The bellows 32 is thus suitable for raising the arm 31 from a lowered rest or maintenance position ß into an operating position cc or, in a reverse pivoting movement 202, for lowering it into the rest or maintenance position ß. In order to avoid damage to the anilox roller 2 or the printing cylinder 4, the pivoting movement 202 of the arm 31 and thus of the anilox roller 2 is mechanically limited. For this purpose, a stop 33 of the pivot arm 31 is provided. In the pivoted position cc, y, the stop 33 is supported as shown in Fig.2 against a fixed counterbearing. An eccentric 34 is used as the counterbearing.

[0026] The eccentric 34 is mounted in the side wall 11 for rotation about a rotation axis 302. Its rotational position can be locked by means not shown. The eccentric 34 enables very precise positioning of the anilox roller 2 relative to the printing cylinder 4 in its operating position cc. In the embodiment shown in Fig. 1, the rotation axis 302 of the eccentric 34 is oriented parallel to the rotation axis 201 of the anilox roller 2.

[0027] In the rest or maintenance position ß, the anilox roller 2 is pivoted far enough away from the printing cylinder 4 to ensure good accessibility for maintenance and setup. During brief production interruptions or gaps in the product flow, it is unnecessary and sometimes undesirable to move the anilox roller 2 so far away from the printing cylinder 4. On the other hand, further ink application by the anilox roller should be prevented. For this reason, an intermediate position y is provided. In this intermediate position y, the distance between the printing cylinder 4 and the anilox roller 2 is sufficiently large that no ink transfer occurs from the anilox roller 2 to the printing cylinder 4.

[0028] In order to be able to assume this intermediate position y, a second feed device 40 is provided. Its actuator is formed by the lifting cylinder 36 shown in Fig. 1. The lifting cylinder 36 is arranged between the pivot arm 31 and the stop 33 of the first feed device 3. Its housing is attached to the holder 35. The stop 33 is fastened to the cylinder rod. The pivot arm 31 is thus, as it were, clamped between the bellows 32 of the first feed device 3 and the lifting cylinder 36 of the second feed device 40. The lifting cylinder 36 is supplied with compressed air via the lines 38. In the compressed air supply 38, a quick-release valve 39 is provided for each cylinder chamber. The quick-release valves 39 allow rapid movement 202 and shorten the reaction time. In addition, switchable valves of a known type, not shown in the figures, are provided in the compressed air lines 38.In order to achieve a higher degree of automation of the printing unit, the valves in the compressed air lines 37, 38 of the bellows 32 and the lifting cylinder 36 are connected to an electronic control 100 of the printing unit.

[0029] The arrangement of the two actuators 32, 36 of the feed devices 3, 40 allows the bellows 32 and the lifting cylinder 36 to operate either in the same direction or in opposite directions relative to the pivoting movement 202 of the arm 31 and the anilox roller 2. The operating directions are controlled by the wiring of the controllable valves (not shown) in the compressed air supplies 37, 38.

[0030] The pneumatic actuators 32, 36 are dimensioned such that the lifting cylinder 36 exerts a greater force than the bellows 32. When acting in the opposite direction, the lifting cylinder 36 overrides the bellows 32. This causes the swivel arm 31 to swivel into the intermediate position y by the force 402 of the lifting cylinder 36, counter to the force 401 of the bellows 32. This intermediate position y is predetermined by the corresponding end stop 41 of the lifting cylinder 36. The end stop 41 is fixed to the swivel arm 31. It swivels with the arm 31. In a simple manner, the end stop 41 is provided by the internal stop of the lifting cylinder 36.

[0031] The first circuit 501 of the bellows 32 and the second circuit 502 of the lifting cylinder 36 during the change from the operating position cc to the intermediate position y are shown in Fig. 3. The second circuit 502 reverses the direction of action of the lifting cylinder 36. At the same time, the bellows 32 is briefly depressurized or vented. This allows the duration of the position change to be further reduced. Reference numeral

[0032] 1 machine frame

[0033] 2 anilox roller

[0034] 3 first delivery device

[0035] 4 printing cylinders

[0036] 11 Wall

[0037] 12 cross members

[0038] 30 swivel bearings

[0039] 31 Arm

[0040] 32 bellows

[0041] 33 stop

[0042] 34 eccentric

[0043] 35 holders

[0044] 36 lifting cylinders

[0045] 37 Compressed air line, bellows

[0046] 38 Compressed air line, lifting cylinder

[0047] 39 Quick exhaust valve

[0048] 40 second delivery device

[0049] 41 End stop

[0050] 100 Control

[0051] 200 transport path

[0052] 201 Anilox roller rotation axis

[0053] 202 Delivery direction

[0054] 301 Rotary axis, arm

[0055] 302 Rotary axis, eccentric

[0056] 401 Actuating force, bellows

[0057] 402 Actuating force, lifting cylinder

[0058] 501 Switching state, bellows

[0059] 502 Switching state, lifting cylinder cc Operating position ß Maintenance position

[0060] Y intermediate position

Claims

Patent claims Printing unit of a printing press or a rotary die cutter for printing on sheets and / or webs as printing material, at least comprising, • a machine frame (1 ) with at least two frame walls (11 ) arranged substantially opposite each other on either side of the product stream (200) and at least one crossbeam (12) connecting the at least two frame walls (11 ) transversely, • a printing cylinder (4) arranged in the machine frame (1) and oriented essentially in a transverse direction with a first axis of rotation, wherein the printing cylinder (4) is designed to transfer printing medium to the substrate, • an anilox roller (2) arranged in the machine frame (1) and oriented essentially in a transverse direction with a second axis of rotation (201) such that the anilox roller (2) and the printing cylinder (4) roll essentially against each other in at least one operating state, • a first feed device (3) connected to the anilox roller (2), comprising at least one first feed drive and an adjustable travel limiter, wherein the distance of the second axis of rotation (201) of the anilox roller (2) to the first axis of rotation of the printing cylinder (4) is variable by the at least one first feed drive, and wherein the smallest possible distance is predetermined by the at least one adjustable travel limiter, and • an electronic control (100) wherein the at least one first feed drive is controllably connected to the at least one electronic control (100), characterized by at least one second feed device (40) connected to the at least one travel limiter and adjusting the at least one travel limiter in its position relative to the anilox roller (2), wherein the at least one second feed device (40) has at least one second feed drive. Printing mechanism according to claim 1, characterized in that the at least one first delivery device (3) comprises at least one fluid-operated bellows (32) as the first delivery drive. Printing mechanism according to any of the preceding claims, characterized in that the at least one second delivery device (40) comprises at least one fluid-operated lifting cylinder (36) as the second delivery drive. Printing mechanism according to claim 3, characterized by at least one rapid emptying valve (39) connected to the at least one lifting cylinder (36) by a pressure line (38).A printing unit according to one of the preceding claims, characterized in that the first feed drive is suitable for applying a first actuating force (401) in a feed direction (202), and that the second feed drive is suitable for applying a second actuating force (402) in the same feed direction (202), wherein the second actuating force (402) of the second feed drive is at least temporarily greater than the first actuating force (401) of the first feed drive, such that the second feed drive is suitable for overriding the first feed drive. A printing unit according to one of the preceding claims, characterized in that the at least one first feed device (3) has at least one arm (31) pivotably arranged about a third axis of rotation (301) on the at least one machine frame (1) and at least one stop (33) arranged on the at least one arm (31) and pivotable together with the at least one arm (31), wherein. • the at least one anilox roller (2) rotatable about its axis (201) in which at least one arm (31) is received, • the at least one first feed drive supports the at least one arm (31 ) against the machine frame (1 ) in such a way that the at least one first feed drive determines the pivot position of the at least one arm (31 ) relative to the machine frame (1 ), • the at least one stop (33) forms the at least one path limiter and to which at least one arm (31) is arranged to be slidable, and • the at least one second feed device determines the position of the at least one stop (33) relative to the at least one arm (31). Printing unit according to claim 6, characterized by at least one eccentric (34) arranged in the at least one machine frame (1), wherein the at least one eccentric (34) is rotatably arranged relative to the machine frame (1) about a fourth axis of rotation (302) and together with the at least one stop (33) of the at least one first feed device (3) forms the at least one travel limiter.Method for positioning an anilox roller (2) to a printing cylinder (4) by means of at least one first feed device (3) with a first feed movement (202), wherein the anilox roller (2) assumes a first end position as a predetermined operating position (a) or a second end position of the feed movement (202) as a predetermined maintenance position (ß) that differs from the operating position (a), characterized by at least one predetermined intermediate position (y) of the anilox roller (2) arranged along a second feed movement, wherein the anilox roller (2) assumes the at least one predetermined intermediate position (y) by means of a second feed device (40).A method according to claim 8, characterized in that the second feed movement of the second feed device is identical to at least a section of the first feed movement (202) of the first feed device (3) and that the at least one intermediate position (y) of the anilox roller (2) is located on the path of movement of the anilox roller (2) described by the first feed movement (202). A method according to claim 8 or 9, characterized in that, during the change from the operating position (a) to the intermediate position (y), a first switching state (501) of the first feed drive of the first feed device is activated. (3) disengages the first delivery drive at least briefly, while a second switching state (502) of the second delivery drive of the second delivery device (40) moves the second delivery device (40) from a first end position to a second end position.

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