Adjustable roller and printing press with multiple printing units using such a roller

Abstract

Roller (13) for a printing unit of a printing press with a roller outer body (14) which is mounted axially reciprocating on a roller inner body (16), wherein the reciprocating movement can be effected by a pneumatic drive by selectively pressurizing a first and a second chamber (32; 33), which are each formed in the interior of the roller in the form of a cylinder-piston system between one or more components (34; 36; 37) fixed to the roller outer body and one or more components (38; 39) fixed to the roller inner body, characterized in that the axially movable parts of the components (34; 36; 37; 38; 39) delimiting the respective chamber (32; 33) form a non-contact seal (41; 42; 43) between them on the side facing each other, that the non-contact seal (41; 42; 43) as gap seal (41; 42;43) and no mechanically effective seal is provided between these axially movable parts relative to each other, that the gap seal (41; 42; 43) has a gap width of at least 0.03 mm and at most 0.15 mm, that the axial length of the gap seal (41; 42; 43) adjoining the chamber (32; 33) is greater than three times a maximum axial stroke (H) and greater than twice the axial extent of the chamber (32; 33), that the surfaces of the mutually facing sides forming the non-contact seal (41; 42; 43) between them have a roughness with an average roughness depth Rz (DIN ISO 1302) of at most 10, that the two chambers (32; 33) are provided on both sides of an annular component (39) fixed to the roller body and are each connected at their end faces by a roller outer body fixed bushing-like component (36; 37) are limited, and that the two chambers (32;33) are supplied with compressed air from each end face of the roller by means of axle stubs projecting from the end face of the roller (13).

Description

[0001] The invention relates to an idler roller and a printing machine with printing units having such a roller according to the preamble of claim 1 or 8.

[0002] DE 196 03 765 A1 discloses an oscillating roller whose outer body, encompassing the outer surface, can be moved back and forth on an axis by applying compressed air to two chambers formed inside the roller. The chambers are sealed from each other and from the outside by seals. An oscillating roller based on the same principle is also disclosed in EP 0 453 847 A1.

[0003] As is known, for example, from WO 2016 / 08705 A1, in the packaging industry, a device or printing press usually uses several printing units for decorating hollow bodies, each having a cylindrical outer surface. Each of these printing units transfers a printing ink to a printing blanket used jointly by these printing units. The outer surface of the respective hollow body is then decorated with a multi-colored print motif, for example, by a relative movement between the outer surface of the respective hollow body and the previously inked printing blanket, in particular by rolling the outer surface of the respective hollow body on this printing blanket. In the printing units, the respective printing form cylinder receives the printing ink via an inking unit comprising several rollers, at least one of which is designed as an iridescent roller, in particular as an iridescent rider roller.

[0004] DE 691 10 808 T2 discloses an oscillating roller that is moved axially back and forth by alternatingly applying pressure to two piston chambers provided on either side of a piston. In one embodiment, the piston-piston chamber system is arranged within the roller body, with the piston being fixed to the axis and the piston chamber bottoms being axially movable on the axis on the inside of the outer roller body.

[0005] DE 196 03 765 A1 discloses a device for axially moving a friction roller. In one embodiment, a sealing wall is provided inside the friction roller on an axially fixed and non-rotating axis, with cavities adjoining it on both sides, which can be pressurized with compressed air to oscillate the outer body. Seals are provided between the axially relatively movable parts.

[0006] DE 10 2005 040 614 A1 relates to an oscillating roller whose interior can be temperature-controlled by the supply and removal of a temperature-control medium. The axle running through the center of the roller is mounted in side frames for rotation and axial displacement. To prevent contamination of the bearing supporting the axle on the frame, a gap seal protecting the bearing is provided, which absorbs any axial relative movement between the frame and the roller.

[0007] In DE 195 39 502 A1, the journal of a variable-speed roller is mounted in the frame for axial movement and rotation. To prevent lubricant supplied to the bearing assembly from escaping, a gap seal is provided between the axles and the bearing bushing fixed to the frame.

[0008] The invention is based on the object of creating an improved variable roller and a printing machine with printing units having such a roller.

[0009] The object is achieved according to the invention by the features of claim 1 and 8. The dependent claims relate to advantageous developments and refinements of the solution found.

[0010] One advantage of a pneumatically driven, i.e., oscillating, roller is its low cost compared to mechanical drive solutions. Because the oscillating drive is integrated into the roller, the drive requires no additional space. It is also particularly easy to retrofit. Such a roller also operates with particularly low wear.

[0011] A design with a partially, predominantly, or even completely contactless sealing system is particularly advantageous. This at least partially or even completely contactless sealing system does not result in any additional friction-related heat generation. Finally, due to the reduced friction of a partially or entirely contactless sealing system, no additional force is required to overcome friction to generate the oscillating stroke.

[0012] An embodiment of the invention is illustrated in the drawings and is described in more detail below.

[0013] The description of the roller according to the invention is presented in connection with a particularly advantageous application in a printing unit of a printing machine for printing hollow bodies, in particular a can printing machine, but is not fundamentally limited thereto.

[0014] They show: Fig. 1 a device for printing or decorating hollow bodies each having a lateral surface with several inking units; Fig. 2 an inking unit, especially for the Fig. 1 illustrated device in a first operating position; Fig. 3 the inking unit, especially for the Fig. 1 illustrated device in a second operating position; Fig. 4 a chamber doctor blade system especially for the Fig. 2 and Fig. 3 shown inking unit; Fig. 5 is an oblique view of a friction roller; Fig. 6 a sectional view through a roller according to Fig. 5.

[0015] Fig. 1 shows, in a simplified schematic representation and by way of example, a device for printing or decorating hollow bodies 01, each having a preferably cylindrical outer surface, e.g. two-part cans 01, wherein these hollow bodies 01 are fed e.g. sequentially by a conveyor device to the transport device, which is designed, for example, as a rotating or at least rotatable feed wheel, in particular as a mandrel wheel 02, and are held there individually on a holder on this transport device. In the following, due to the selected embodiment of the printing press or for the device comprised thereby for printing hollow bodies, it is assumed that this transport device is preferably designed as a mandrel wheel 02. An ink-transferring device 03, e.g. a rotating or at least rotatable segment wheel 03, preferably cooperates with the mandrel wheel 02, along the ora plurality of printing blankets are arranged one behind the other around the circumference of which. In association with the segment wheel 03 mentioned as an example, a plurality of printing forme cylinders 04, in particular plate cylinders 04, are provided along its circumferential line, which are radially positioned or at least positionable against this segment wheel 03, wherein a printing form, in particular a printing cliché, is arranged on the respective outer surface of each of these printing forme cylinders 04 or plate cylinders 04, wherein this printing cliché is particularly suitable for carrying out a letterpress process. Each of the printing forme cylinders 04 or plate cylinders 04 is supplied with a specific printing ink by means of an inking unit 06 for inking its printing form or printing cliché. In the following, it is assumed by way of example that the printing forme cylinders 04 are each designed as a plate cylinder 04 carrying at least one printing cliché.

[0016] Fig. 2 and Fig. 3 show in a simplified schematic representation some details of the inking unit 06 which interacts with a plate cylinder 04 and which is designed, for example, for use in the Fig. 1 is provided for printing or decorating, in particular, hollow bodies 01, each preferably having a cylindrical outer surface. The inking unit 06 proposed here advantageously has a very short roller train, i.e. consisting of only a few, preferably a maximum of five, rollers, in particular a two-roller roller train, for transporting the ink from an ink reservoir to the relevant plate cylinder 04. In the case of the two-roller roller train, this roller train consists of only a single roller 07, e.g. ink forme roller 07, and a roller 08, preferably designed as an anilox roller 08, e.g. inking unit roller 08. An inking unit 06 with a roller train consisting of a maximum of five rollers belongs to the class of short inking units.

[0017] Fig. 2 shows, by way of example, a (short) inking unit 06 with a two-roller roller train in a first operating position, in which the ink forme roller 07 and the anilox roller 08 are positioned against each other, the ink forme roller 07 is positioned against the plate cylinder 04 and the plate cylinder 04 is also positioned radially against the device 03, in particular against the segment wheel 03, which transfers the printing ink from the plate cylinder 04 to the outer surface of the respective hollow body 01. Fig. 3 shows, however, for the Fig. 2, the inking unit 06 has a second operating position in which the ink form roller 07 and the anilox roller 08 are separated from each other, the ink form roller 07 is separated from the plate cylinder 04, and the plate cylinder 04 is separated from the ink-transferring device 03, in particular from the segmented wheel 03. The engagement and disengagement mechanism will be discussed later.

[0018] The printing form cylinder 04, which is preferably designed as a plate cylinder 04, and the inking unit roller 08, which is preferably designed as an anilox roller 08, are each independently driven in rotation by a motor 11; 12, in particular in the preferred embodiment used in the Fig. 2 and Fig. 3, wherein the respective motor 11; 12 is, for example, regulated or at least controllable in its respective speed and / or angular position by, for example, an electronic control unit. The printing ink transferring device 03, which is designed, for example, as a segmented wheel 03, is rotationally driven, for example, by its own drive or by a central machine drive. The ink forme roller 07 is or is driven rotationally by the anilox roller 08 by friction. In the preferred embodiment, an outer diameter d07 of the ink forme roller 07 and an outer diameter d04 of the plate cylinder 04 carrying at least one printing form, in particular at least one printing cliché, are equal in amount.At least one printing plate is arranged or at least can be arranged on the outer surface of the plate cylinder 04, so that in the embodiment with the same outer diameters d04; d07, the plate cylinder 04 carrying the printing plate and the ink forme roller 07 each have an identical circumferential length. In the preferred embodiment, in the first operating position of the inking unit 06 interacting with the plate cylinder 04, in which the ink forme roller 07 and the anilox roller 08 are positioned against one another, the ink forme roller 07 is positioned against the plate cylinder 04, and the plate cylinder 04 is positioned against the segment wheel 03, at least the respective centers of the plate cylinder 04, the ink forme roller 07, and the anilox roller 08 are positioned along the same straight line G. To detect the rotation of the ink forme roller 07, a detection device, e.g.provided in the form of a rotary encoder, wherein this rotary encoder is in particular rigidly connected to a shaft of the inking roller 07. The signal generated by the rotary encoder during rotation of the inking roller 07 is used by the control unit to set the speed and / or angular position of the inking roller 07 by means of the rotation of the anilox roller 08 or, if necessary, to adjust it in such a way that synchronization between the plate cylinder 04 and the inking roller 07 is established or is established, so that the peripheral speed of the inking roller 07 corresponds to the peripheral speed of the plate cylinder 04 within previously defined permissible tolerance limits.To achieve this goal, it can be provided that the control unit, preferably during the adjustment phase it carries out, sets the peripheral speed of the anilox roller 08 in such a way that it has a lead or lag compared to the peripheral speed of the plate cylinder 04, especially for a short time - and thus not permanently. By designing the plate cylinder 04 and the ink forme roller 07 with the same circumferential length and by setting the synchronization between the plate cylinder 04 and the ink forme roller 07, the effect of stenciling, which is detrimental to the print quality, is largely avoided. The drive concept described here with a friction-driven ink forme roller 07 also has the advantage that a separate drive is not required for the ink forme roller 07, which saves costs and, due to the simpler mechanical construction, is also easier, e.g.makes it easier to replace the ink application roller 07 during maintenance or repair work.

[0019] The inking roller 07, in its preferred embodiment, has a closed, preferably rubberized outer surface. The inking unit roller 08, preferably designed as an anilox roller 08, has a outer surface coated, for example, with a ceramic coating, wherein a pattern of, for example, 80 lines per centimeter of axial length of the anilox roller 08 or a cup structure is formed in the ceramic layer. In order to enable the anilox roller 08 to feed the largest possible amount of printing ink into the roller train of the inking unit 06 with each of its revolutions, the outer diameter d08 of the anilox roller 08 is preferably larger than the outer diameter d07 of the inking roller 07. The anilox roller 08 should therefore have the largest possible conveying volume. Fig. 2, the respective direction of rotation of the segment wheel 03, the plate cylinder 04, the ink forme roller 07 and the anilox roller 08 is indicated by a direction of rotation arrow.

[0020] In the preferred embodiment, at least the inking roller 08, which is preferably designed as an anilox roller 08, has a temperature control device with the aid of which the outer surface of this roller is temperature-controlled. The temperature control device of the anilox roller 08 operates, for example, with a temperature control fluid introduced into the interior of the anilox roller 08, wherein the temperature control fluid is, for example, water or another liquid coolant. The temperature control device of the anilox roller 08 can be used to influence the conveying volume of the anilox roller 08, since this influences the viscosity of the printing ink to be transported by the inking roller 06. The conveying volume of the anilox roller 08 and the viscosity of the printing ink to be transported by the inking roller 06 ultimately influence the ink density of the printing ink to be applied to the cylindrical outer surface of the hollow body 01 to be printed.The thickness of an ink film formed by the printing ink to be applied to the cylindrical surface of the hollow body 01 to be printed is, for example, approximately 3 µm.

[0021] The ink reservoir of the inking unit 06 is designed, for example, as a chambered doctor blade system 09 acting in conjunction with the anilox roller 08. In this chambered doctor blade system 09, at least one ink tray, a doctor blade bar positioned or at least adjustable axially parallel to the anilox roller 08, and preferably also a pump for conveying the printing ink advantageously form a single structural unit. This chambered doctor blade system 09 is held or mounted in the inking unit 06, i.e. on a frame of the inking unit 06, preferably only on one side, e.g. by a suspension, so that this structural unit can be easily removed from the inking unit 06 and thus replaced laterally after it has been detached from the frame of the inking unit 06, i.e. by a movement directed axially parallel to the anilox roller 08, e.g. by pulling on a handle arranged on this structural unit. This structural unit of the chamber doctor blade system 09 preferably forms a cantilever arm on a side frame of the inking unit 06. Fig. 4 shows a perspective view of the chamber doctor blade system 09, designed as a single structural unit, in interaction with the anilox roller 08 of the inking unit 06.

[0022] After the anilox roller 08 has taken up printing ink from the ink reservoir, i.e. in particular from the chambered doctor blade system 09, the anilox roller 08 transports this printing ink immediately and directly or via further rollers of the roller train belonging to the inking unit 06 to the preferably only one ink application roller 07.

[0023] To ensure better ink distribution in the inking unit 06, a roller 13 of the inking unit 06 is preferably designed as an idler roller 13, e.g., a distributor roller 13. Such a distributor roller 13 can be provided directly in the roller train of an inking unit 06 designed as a roller inking unit, but in the embodiment shown here is designed as a so-called rider roller 13 that interacts with the circumference of one of the rollers 07; 08 of the inking unit 13, in particular the short inking unit 06. In the advantageous embodiment presented here, it is designed as an idler roller 13 that interacts with the outer surface of the anilox roller 08.

[0024] The variable friction roller 13, embodied here by way of example as a rider roller 13, is preferably positioned or at least adjustable against the anilox roller 08, for example, in an area between the chambered doctor blade system 09 and the ink forme roller 07 following the chambered doctor blade system 09 positioned against the anilox roller 08 in the direction of rotation of the anilox roller 08, in order to improve the uniformity of the ink application on the anilox roller 08 and its ink transport. The rider roller 13 is arranged axially parallel to the anilox roller 08. Contrary to other possible embodiments, the friction roller 13, embodied here as a rider roller 13, is not considered to be part of the roller train of the inking unit 06, since it does not transfer any printing ink from the anilox roller 08 to another roller. The rider roller 13, which is rotationally driven here by the anilox roller 08, e.g. by friction, has, for example, a rubberized outer surface. In principle, the friction roller 13 can also be driven directly by a motor via a gear.The rider roller 13 attached to the anilox roller 08, as it rolls along the outer surface of the anilox roller 08, sucks a portion of the printing ink picked up by the anilox roller 08 from the chamber doctor blade system 09 from the hasher or cells of the anilox roller 08 and deposits this printing ink at least partially onto webs formed on the outer surface of the anilox roller 08. As a result, the rider roller 13 rolling on the anilox roller 08 causes the anilox roller 08 to deliver a larger quantity of printing ink to the ink forme roller 07. As a further consequence, in the case of an anilox roller 08 having, for example, a temperature control device, the effectiveness of controlling the ink density is also improved because the rider roller 13 rolling on the anilox roller 08 contributes to providing a larger quantity of printing ink. The rider roller 13 rolling on the anilox roller 08 thus reduces regardless of the specific design of the anilox roller 08, iewith or without a tempering device, both density differences that can arise due to manufacturing tolerances of the anilox roller 08, as well as the risk of visibility of the hash or cells of the anilox roller 08 on the printing material, ie here on the outer surface of the hollow body 01 to be printed as a result of an ink application that is at least partially too low.

[0025] The respective adjustment and / or de-adjustment of printing form cylinder or plate cylinder 04, ink forme roller 07 and / or anilox roller 08 and / or an adjustment of a contact pressure exerted by them is carried out with an example shown in the Fig. 2 and Fig. 3, which will now be described in more detail. In the preferred embodiment, the printing forme cylinder or plate cylinder 04 is mounted, in particular, at both ends on a load arm of a preferably one-sided first lever arrangement 18 consisting of a force arm and the load arm, wherein the force arm and the load arm of this first lever arrangement 18, which is arranged at a fixed angle to the force arm, are jointly pivotable about a first axis of rotation 19 directed axially parallel to the plate cylinder 04. In an operative connection to the force arm of the first lever arrangement 18, a first drive 21, for example in the form of a hydraulic or pneumatic working cylinder, is arranged to exert a torque about the first axis of rotation 19 and is preferably controllable by a control unit. When this first drive 21 is actuated, depending on its direction of action, the printing forme cylinder or plate cylinder arranged on the load arm of this first lever arrangement 18Plate cylinder 04 is either positioned away from a printing blanket, e.g., the segmented wheel 03, or positioned against it. To limit the contact pressure exerted by the printing forme cylinder or plate cylinder 04 against the respective printing blanket, e.g., the segmented wheel 03, a first stop 22 is provided, for example, for the force arm of the first lever arrangement 18, by means of which a path traveled by the pivoting movement of the printing forme cylinder or plate cylinder 04 against the segmented wheel 03 is limited. The contact pressure exerted by the printing forme cylinder or plate cylinder 04 against the segmented wheel 03 can be adjusted using the first drive 21.

[0026] In the preferred embodiment, the inking roller 07 is also mounted, in particular, at both ends on a load arm of a preferably one-sided second lever arrangement 23 consisting of a force arm and the load arm, wherein the force arm and the load arm of this second lever arrangement 23 are jointly pivotable about the first axis of rotation 19 directed axially parallel to the plate cylinder 04. Likewise, in the preferred embodiment, the inking unit roller 08, designed, for example, as an anilox roller 08, is also mounted, in particular, at both ends on a load arm of a preferably one-sided third lever arrangement 24 consisting of a force arm and the load arm, wherein the force arm and the load arm of this third lever arrangement 24 are jointly pivotable about a second axis of rotation 26 directed axially parallel to the anilox roller 08, wherein the second axis of rotation 26 of the third lever arrangement 24 is arranged on the second lever arrangement 23.The second rotational axis 26 on the second lever arrangement 23 is preferably stationary. A preferably controllable second drive 27 is arranged on the load arm of the first lever arrangement 18. When actuated, it acts on the force arm of the second lever arrangement 23. By means of this second drive 27, the ink forme roller 07 can be adjusted to or detachable from the plate cylinder 04, depending on the direction of action of the second drive 27. A preferably controllable third drive 28 is arranged on the load arm of the second lever arrangement 23. When actuated, it acts on the force arm of the third lever arrangement 24. By means of this third drive 28, the anilox roller 08, preferably together with the chambered doctor blade system 09, can be adjusted to or detachable from the ink forme roller 07, depending on the direction of action of the third drive 28. The second drive 27 and / or the third drive 28 are each designed, for example, in the form of a hydraulic or pneumatic working cylinder.It can be provided that the second drive 27 and the third drive 28 are, for example, actuated jointly and preferably also simultaneously, or at least can be actuated. The pivoting movement of the load arm of the second lever arrangement 23 is, for example, limited by a preferably adjustable first stop system 29, in particular one that can be adjusted by an eccentric, whereby the contact pressure exerted by the inking roller 07 against the printing forme cylinder or plate cylinder 04 is also limited or at least can be limited. The pivoting movement of the load arm of the third lever arrangement 24 is, for example, limited by a preferably adjustable second stop system 31, in particular one that can be adjusted by an eccentric, whereby the contact pressure exerted by the anilox roller 08 against the inking roller 07 is also limited or at least can be limited. Fig. 2 shows, by way of example, a first operating state in which the first drive 21 and the second drive 27 and the third drive 28 are each inoperative or in their idle state, whereby the anilox roller 08 is engaged with the inking roller 07 and the inking roller 07 is engaged with the printing forme cylinder or plate cylinder 04 and the printing forme cylinder or plate cylinder 04 is engaged with the segment wheel 03. Fig.3 shows, by way of example, a second operating state in which the first drive 21 and the second drive 27 and the third drive 28 are each actuated or in their working state, whereby the anilox roller 08 is separated from the ink forme roller 07 and the ink forme roller 07 is separated from the printing forme cylinder or plate cylinder 04, and the printing forme cylinder or plate cylinder 04 is separated from the segmented wheel 03. The respective force arm and / or load arm of the three aforementioned lever assemblies 18; 23; 24 is / are each designed, for example, as a pair of opposing lever rods or side frame walls, between which either the printing forme cylinder or plate cylinder 04 or the ink forme roller 07 or the anilox roller 08 is arranged in the respective previously described arrangement.The three aforementioned lever arrangements 18; 23; 24 are each arranged in different vertical planes spaced apart from one another, so that they do not interfere with each other in their respective pivoting ability.

[0027] Basically independent of the specific design of the printing press, the printing unit and / or the inking unit 06, but advantageous in conjunction with the aforementioned design, and basically independent of the design of the inking unit 06 and / or the location of the friction roller 13, but advantageous in conjunction with the aforementioned arrangement in a short inking unit 06 and / or with the design as a rider roller 13, the idler roller 13 is designed as a pneumatic idler roller 13, as explained below.

[0028] The roller 13 comprises an outer roller body 14, which is mounted on an inner roller body 16 for axial reciprocation, wherein the reciprocation is effected by a pneumatic drive. The supply of compressed air occurs, for example, via valves from a compressed air source 17, which is only indicated schematically. For the reciprocation, a first and a second chamber 32; 33, which are each formed in the interior of the roller in the manner of a cylinder-piston system between one or more components 34; 36; 37 fixed to the outer roller body and one or more single-part or multi-part components 38; 39, e.g., components 38; 39, can be pressurized with compressed air.The (respective) roller outer body-fixed component 34; 36; 37 can be formed by a cylindrical roller shell body 34 of the roller outer body 14 itself or preferably by components 36, 37, in particular bushings 36; 37, molded onto or inserted into the inside thereof. The roller inner body-fixed component 38; 39 can be formed by a cylindrical axis 38 or shaft 38 of the roller inner body 16 itself or preferably by a component 39, in particular a ring 39, molded onto or inserted into the outside thereof.

[0029] However, the parts of the components 34; 36; 37; 38; 39 that are axially movable relative to one another and delimit the respective chambers 32; 33 are not designed by seals that act as a mechanical barrier and / or are not sealed against one another with significant contact, but rather form a non-contact seal 41; 42; 43 between them on the side facing one another. Although they can also be designed with one or more grooves or single- or multi-thread labyrinth seals, the non-contact seals 41; 42; 43 are preferably designed as simple gap seals 41; 42; 43 and / or no mechanically effective seal is provided between these parts that are axially movable relative to one another. A gap width of at least 0.03 mm and at most 0.15 mm, preferably at least 0.05 mm and at most 0.10 mm, is preferably provided.

[0030] An axially extending length of the gap seal 41; 42; 43 adjoining the chamber 32; 33 is greater than three times a maximum axial stroke H and / or than twice an axial extension of the chamber 32; 33 and / or than one tenth of the, in particular usable, cylinder barrel length L13.

[0031] The two chambers 32; 33 are preferably provided on both sides of the annular component 39 fixed to the inner roller body and are each delimited at the end by a bush-like component 36; 37 fixed to the outer roller body.

[0032] In an advantageous embodiment, a non-contact seal 41; 42; 43, in particular a gap seal 41; 42; 43, is provided between the outwardly directed side of the component 39 fixed to the inner roller body and the inwardly directed side of the outer roller body 14, in particular a cylindrical roller shell body 34, and / or between the inwardly directed side of the respective component 36; 37 fixed to the outer roller body and an outwardly directed side of the inner roller body 16, in particular a shaft 38 or axle 38 carrying the outer roller body 14.

[0033] The surfaces of the mutually facing sides accommodating the non-contact seal 41; 42; 43 between them have a roughness with an average roughness depth Rz (DIN ISO 1302) of, for example, at most 10, preferably at most 4.

[0034] The inner roller body 16 preferably comprises or is designed as an axle 38 supporting the outer roller body 14 via roller bearings 44. The two chambers 32; 33 are preferably supplied with compressed air from each roller end face through axle stubs protruding from the end face of the roller 13 via corresponding channels 47; 48, e.g., bores 47; 48.

[0035] The rolling bearing 44 must have a running surface widened by at least the lateral stroke of the roller 13.

[0036] The roller shell body 34 encompassed by the roller outer body 14 preferably carries a plastic layer 46, in particular a layer 46 made of Rilsan®, on its shell surface or is formed by such a layer. List of reference symbols 01 Hollow body, two-part can 02 Mandrel wheel 03 Ink transfer device, segment wheel 04 Printing form cylinder, plate cylinder 05 - 06 Inking unit, short inking unit 07 Roller, ink application roller 08 Roller, inking roller, anilox roller 09 Chamber doctor blade system 10 - 11 Engine 12 Engine 13 roller, friction roller, rider roller 14 roller outer body 15 - 16 roller inner body 17 Compressed air source 18 Lever arrangement, first 19 Rotation axis, first 20 - 21 drive, first 22 attack, first 23 Lever arrangement, second 24 Lever arrangement, third 25 - 26 Rotation axis, second 27 Drive, second 28 drive, third 29 Stop system, first 30 - 31 Stop system, second 32 Chamber, first 33 Chamber, second 34 Component, roller shell body 35 - 36 component, part, socket 37 component, part, socket 38 Component, Axis, Shaft 39 Component, Ring 40 - 41 non-contact seal, gap seal 42 non-contact seal, gap seal 43 non-contact seal, gap seal 44 rolling bearings 45 - 46 plastic layer, layer 47 Canal, borehole 48 channel, bore d04 outer diameter d07 outer diameter d08 outer diameter G Straight H Hub L13 Cylinder barrel length

Claims

[1] Roller (13) for a printing unit of a printing press with an outer roller body (14) which is mounted on an inner roller body (16) so as to be axially reciprocable, the reciprocating movement being effected by a pneumatic drive in that a first and a second chamber (32; 33), which are each formed in the interior of the roller in the manner of a cylinder-piston system between one or more components (34; 36; 37) fixed to the outer roller body and one or more components (38; 39) fixed to the inner roller body, can be pressurised with compressed air, characterized bythat the parts of the components (34; 36; 37; 38; 39) which are axially movable relative to one another form a non-contact seal (41; 42; 43) on the side facing one another, that the non-contact seal (41; 42; 43) is designed as a gap seal (41; 42; 43) and no mechanically effective seal is provided between these parts which are axially movable relative to one another, that a gap width of at least 0.03 mm and at most 0.15 mm is provided for the gap seal (41; 42; 43), that an axially extending length of the gap seal (41; 42; 43) adjoining the chamber (32; 33) is greater than three times a maximum axial stroke (H) and greater than twice an axial extension of the chamber (32; 33) that the surfaces of the mutually facing, non-contact seal (41; 42;43) have a roughness with an average roughness depth Rz (DIN ISO 1302) of at most 10 between the sides that form, that the two chambers (32; 33) are provided on both sides of an annular component (39) that is fixed to the inner roller body and are each delimited at the end by a bush-like component (36; 37) that is fixed to the outer roller body, and that the two chambers (32; 33) are each supplied with compressed air from a respective roller end face by means of axle stubs that project from the end face of the roller (13); [2] Roller according to claim 1 characterized by that a gap width of at least 0.05 mm and at most 0.10 mm is provided for the gap seal (41; 42; 43). [3] Roller according to claim 1 or 2, characterized by that an axially extending length of the gap seal (41; 42; 43) adjoining the chamber (32; 33) is greater than one tenth of the cylinder barrel length (L13). [4] Roller according to claim 1, 2 or 3, characterized bythat a non-contact seal (41; 42; 43) is provided between an outwardly directed side of the component (38) fixed to the inner roller body and an inwardly directed side of the outer roller body (14) and / or between an inwardly directed side of the respective component (36; 37) fixed to the outer roller body and an outwardly directed side of the inner roller body (16). [5] Roller according to claim 1, 2, 3 or 4, characterized by that the surfaces of the mutually facing sides forming the non-contact seal (41; 42; 43) between them have a roughness with an average roughness depth Rz (DIN ISO 1302) of at most 4. [6] Roller according to claim 1, 2, 3, 4 or 5, characterized by that the roller inner body (16) comprises or is designed as an axle (38) supporting the roller outer body (14) via roller bearings (44). [7] Roller according to claim 6, characterized bythat the two chambers (32; 33) are each supplied with compressed air from one end face of the roller by means of axle stubs projecting from the end face of the roller (13). [8] Printing machine for decorating hollow bodies each having a cylindrical outer surface, with a plurality of printing units, each comprising a forme cylinder (04) and an inking unit (06), which cooperate via the forme cylinder (04) with a same printing blanket of a device (03) transferring the printing ink to the hollow bodies to be printed, characterized by that the inking unit (06) comprises a friction roller (13) which is designed according to the roller (13) according to one of claims 1 to 7.

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