EP2639064A1 - Flexographic printing unit - Google Patents

Abstract

The element has a printing roller (1) i.e. anilox roller, supporting a printing plate (4), and an application roller (5) transmitting printing ink directly to the printing plate. The application roller comprises a roller core (10) and a case (11) surrounding the rolling core. An outer sheath of the case is provided with a grid, where an inner sheath of the case comprises a clamping surface, which is clamped against a tensioning unit from inside. The tensioning unit is a component of the roller core. A cylindrical sleeve is lengthwise-movable on a longitudinal portion of the roller core. The cylindrical sleeve is designed as an axial load transferring printing unit.

Description

The invention relates to a flexographic printing unit according to the preamble of claims 1 and 2.

A flexographic printing unit is generally composed of an applicator roll over which the printing form is inked, a printing cylinder accommodating the printing form, and an impression cylinder. The application roller in flexographic printing is an anilox roller with which a good ink dosage can be achieved during transfer to the printing form. Anilox roll surfaces are usually made of chrome or ceramic with engravings machined into the surface, usually in the form of small wells. During the printing process, the cups serve to store the color before it is subsequently transferred to the raised parts of the printing form, but always leaving a residue of color in the individual cups.

For the storage of the ink in the wells of the applicator roll, two methods have become established in practice, namely the dip rolling method and the chamber doctor blade method. In the former, the applicator roller or anilox roller is preceded by a fountain roller, which runs on a part of its circumference through a paint tray. The fountain roller picks up color as it passes through the ink tray and passes it to the anilox roller. Excess paint can be wiped off with the aid of a doctor blade, which stands sharply against the outer surface of the anilox roller. Also in the alternative chamber doctor blade method excess ink is stripped off with a doctor blade from the outer shell of the anilox roller. However, the ink is not absorbed via an upstream dipping roller, but pumped into a tight fitting against the outer shell of the anilox chamber from which the color therefore passes directly to the outer surface of the anilox roller.

For a change in the flexographic printing job, it is often necessary in practice to exchange the applicator roller for a different type or an application roller provided with a different screen pattern. If the flexographic printing by the dipping roller method, also often a change of the upstream dipping roller is required. The change of these rollers leads in practice to a high conversion costs and thus to changeover times, which are not available for flexographic printing and are therefore financially burdensome.

The invention is therefore an object of the invention to provide a printing unit for the flexographic printing process, which allows for changes in flexographic printing higher flexibility due to a lower conversion effort.

To solve this problem, a flexographic printing unit according to claim 1 is proposed, in which the applicator roll composed of a roll core and a roll core surrounding the sleeve whose outer shell is provided with a grid, and which has at least one clamping surface on its inner shell, against the clamping means of are radially clamped inside, the clamping means are part of the roll core of the applicator roll.

To solve the problem, a flexographic printing unit according to claim 2 is also proposed, in which the fountain roller from a roll core and a roll core surrounding the immersion sleeve together, which has at least one clamping surface on its inner shell, against the clamping means from the inside are tensioned, wherein the clamping means Part of the roll core of the fountain roller are.

Advantageous embodiments of this flexographic printing unit are specified in the subclaims.

According to a further embodiment of the printing unit, the clamping means comprise at least one spreading device which can be actuated from the inside against the clamping surface. The spreading device, which may be of the mechanical or hydraulic type, exerts a radially outward directed radial pressure on the respective clamping surface.

According to a further embodiment, a component of the spreading device is at least one expanding element which can be expanded outwards. However, an embodiment in which components of the spreading device are a first, expandable to the outside expander at one end of the roller core and at least one further, expandable outward expansion element at the other end of the roller core is particularly preferred.

According to a further embodiment, the expansion element by means of a pressure element is expandable, which is adjustable in the longitudinal direction of the axis of rotation and thereby exerts an axial pressure on the expansion element.

A further embodiment is characterized by a thrust transmitting sleeve as a pressure element. This bushing may be a screw-threaded on an external thread of the roll core threaded bush. Alternatively or additionally, the pressure element can be a cylindrical bushing that can be moved longitudinally along a longitudinal section of the roller core. In the latter case, this sleeve is on the one hand axially supported relative to the first expansion element, and on the other hand relative to the further expansion element, so that it forwards the expansion required for the expansion of the first expansion element on the second or further expansion element.

In a further embodiment, it is proposed that the roller core of the applicator roller or the immersion roller consist of a central base body and the longitudinally arranged one behind the other and in the axial direction against each other supporting components threaded bushing, first expansion element, another bushing and further expansion element, and that the further spreading element axially supported against a collar, which is rigidly arranged on the base body.

With regard to the structure of the exchangeable sleeve is proposed that it is in several parts and composed of an elongated body and at least one inner pressure sleeve inserted therein. The pressure sleeve extends only over part of the length of the body, wherein the clamping surface is located exclusively on the pressure sleeve. In this way it is cost possible, the body z. B. made of light metal, however, the pressure applied to the full clamping pressure sleeves made of a particularly pressure-stable metal material, eg. B. steel.

With a further embodiment, it is proposed that the roller core is rotatably mounted with its first end in a first side part, and with its second, driven end in a second side part, wherein the first side part is provided around the pivot bearing with an opening whose diameter to the axial Removing the sleeve is greater than the outer diameter of the sleeve.

Fig. 1

ein Flexodruckwerk in einer schematischen Seitenansicht;

Fig. 2

in einem Längsschnitt die Rasterwalze des Flexodruckwerks einschließlich der Lagerung der Rasterwalze in den beiden Seitenteilen des Druckwerks;

Fig. 3

in einem Längsschnitt ausschließlich die Rasterwalze, bestehend aus einem Walzenkern und einer darauf durch mechanische Spannmittel gespannten Hülse und

Fig. 4

in einem Längsschnitt eine alternative Ausführungsform der Rasterwalze, bestehend aus einem Walzenkern und einer darauf durch hydraulische Spannmittel gespannten Hülse.

The invention will be explained in more detail below with reference to several exemplary embodiments illustrated on the drawing and the indication of further advantages. On the drawing show:

Fig. 1

a flexographic printing in a schematic side view;

Fig. 2

in a longitudinal section, the anilox roller of the flexographic printing unit including the storage of the anilox roller in the two side parts of the printing unit;

Fig. 3

in a longitudinal section only the anilox roller, consisting of a roller core and a tensioned by mechanical clamping means sleeve and

Fig. 4

in a longitudinal section an alternative embodiment of the anilox roller, consisting of a roller core and a tensioned by hydraulic clamping means sleeve.

The Fig. 1 shows a highly schematic representation of a flexographic printing in the design with dipping roller. As a pressure roller is used a replaceable on its outer circumference printing plates 4 receiving plate cylinder 1, in two side parts 8A, 8B ( Fig. 2 ) of the printing unit is rotatably mounted, and rests with its outer periphery against a counter-rotating to the plate cylinder 1 counter-pressure roller 3. Passed between the platen 1 and counter-pressure roller 3 is the substrate to be printed 2, z. B. a paper web, a film, a substrate etc ..

The printing cylinder or cliché cylinder 1 consists of a cylinder core 1A, which in most cases remains uniform in practice, and an exchangeable cylinder sleeve 1 B. The cylinder sleeve 1B accommodates the printing plates on the outside and has a specific diameter for a given flexographic printing format, and opposes the format change another cylinder sleeve with different diameter interchangeable.

The applicator roller 5 is preceded by a running in a paint tray 7 and partially immersed in the ink fountain immersion roller 6. Against the screen or applicator roller 5 can be designed in a conventional manner squeegee 9 abut, which may be formed, for example, as a doctor blade.

The application roller 5 is composed of a rotatably mounted at its ends in the side parts 8A, 8B roller core 10, and an externally seated on the roller core, interchangeable sleeve 11. Between the roller core 10 and the sleeve 11 is preferably a clearance fit, ie in any case no interference fit , In the case of a separate rotary drive of the applicator roller 5, this engages only on the roller core 10.

According to Fig. 1 not only does the applicator roll, but also the fountain roller 6 consist of a roller core 20 rotatably mounted at its ends in the side parts 8A, 8B and a replaceable immersion sleeve 21 seated on the outside of the roller core. The sleeve 21 of the fountain roller 6 is provided for optimum color adhesion and spreading with a rubberized lateral surface or such of a thermoplastic.

In the case of a separate rotary drive of the fountain roller 6, this engages only on the roller core 20. The fountain roller 6 is adjustable against the anilox roller 5. The speed of the rollers 5 and 6, which are in opposite directions ( Fig. 1 ) or in the same direction, is different. In practice, the fountain roller 6 only runs at about one third of the speed of the anilox roller. 5

The anilox roller 5 releases the color particles from the sieve cups on their surface. The flushing of the ink in the wells is carried out either by the counter-rotating to the anilox roller 5 immersion roller 6, or directly through the ink supply in a - not shown on the drawing - chambered doctor blade, in which case the dip roller deleted.

Due to the design of the applicator roller 5 and the fountain roller 6 with an inner roller core 10 and 20, in which also the elements of the two-sided pivot bearing, as well as a replaceable on the core tensionable sleeve 11 and 21, depending on the application, a quick change possible. In this case, the clamping of the sleeve 11 and 21 via clamping means 40, which are preferably relaxed during the replacement of the sleeve 11 and 21 and tensioned during the actual operation of the flexographic printing unit. Because an essential factor in the print quality is the coloring by means of the dipping and application roller. Depending on the substrate, motif and the flexographic printing inks used, these rollers must be individually tailored to the application. Depending on the application, this results in a change of the rollers 5, 6 as a function of the base to be printed, the quality, the strength of this base and the grid. The conventional replacement of at least the entire applicator roll, possibly also the fountain roller, however, is time consuming and therefore costly.

Due to the construction of the roll core 10, 20 and thereon tensionable, replaceable sleeve changes quickly and easily possible, the existing sleeve 11, 21 is replaced by another, application technology specifically suitable sleeve preferably having the same outer diameter. The respective roller core 10 and 20, however, remains one and the same. In this way, it is possible for each type of multicolored printed products to set up the inking so that an optimal printing effect is achieved.

Although the invention is described in the figures with reference to an anilox roller 5 with negative doctor blade 9, but it is also suitable in a chambered doctor blade process, ie a flexographic printing process with ink supply to the anilox roller 5 by an attached to the anilox roller chamber doctor blade, which is filled with the flexographic ink.

Fig. 2 shows the example of the anilox roller 5 whose installed position between the two side parts 8A, 8B of the printing unit, and Fig. 3 only the anilox roller 5 itself with its individual parts, wherein in turn the fountain roller has the same basic structure.

The center of the roller core forms a solid solid shaft designed base body 12 which is designed over the effective roller length is substantially cylindrical, and at the ends of tapered bearing pins 12A, 12B are formed. In the region of both ends of the substantially cylindrical portion of the main body 12 are the radially acting clamping means 40th

In the embodiment of the FIGS. 2 and 3 the clamping means 40 are designed as purely mechanical spreading devices 42. They consist of a first expansion element 43A in the FIGS. 2 and 3 left roll end, and a second expansion element 43B at the right end of the roll.

The base body 12 of the roller core 10 is provided at both ends, already outside the actual roller section, with the bearing pins 12A, 12B, and mounted by means of these pins in the stationary side parts 8A, 8B. On the one pin 12 B also engages the rotary drive of the anilox roller 5 or, if the roller is the fountain roller 6, the rotary drive.

Each expansion element 43A, 43B consists of a corrugated ring. When pressure is exerted in the direction of the axis of rotation A it comes by deformation effects to a radial expansion of the expansion element 43A, 43B, whereby this spans radially against a cylindrical clamping surface 41 on the inner shell of the interchangeable sleeve 11, 21.

Between the spreading elements 43A, 43B extends, with these frontally in contact, an elongated sleeve 45, which serves for the axial pressure transmission. The bush 45 sits axially freely movable on the cylindrical portion of the body 12. The right spreader 43 B is axially supported against a collar 46 which is rigidly secured to the base 12, or may be one-piece part of the body 12.

At the other end of the anilox roller 5 a threaded bushing 49 is screwed onto an external thread 47 of the base body 12, which is provided for this purpose with a corresponding internal thread. The threaded bush 49 is axially against the spreader 43A from the outside. It can be secured against rotation by a grub screw.

By screwing the threaded bush 49 on the base body 12 of the roller core, this bushing 49 moves in the axial direction, whereby pressure is exerted on the spreader 43A, and this spans. A portion of the longitudinal pressure thus constructed is transmitted to the other spreader 43B via the longitudinally movable bushing 45, which is incompressible. Since the expansion element 43B can not escape outward due to its firm support on the collar 46, the expansion element 43B also tensions. As a result, both expansion elements 43A, 43B undergo a radial expansion, and thus the desired clamping force against the sleeve 11 from the inside.

In order to keep clamping force losses low, separate pressure-receiving sleeves 13A, 13B are inserted into the base body 50 of the sleeve 11 on those longitudinal sections on which the clamping means 40 are located, on each of which the cylindrical clamping surface 41 is located. The pressure receiving sleeves 13A, 13B are made of a stronger material than the main body 50 of the sleeve 11, preferably the pressure receiving sleeves 13A, 13B are steel bushings.

According to Fig. 2 is to replace the sleeve 11 and 21, the one side part 8A of the printing unit with an outwardly pivotable about a hinge 54 bearing receptacle 55 is provided. On the other hand, the right pivot bearing 52B sits directly in the corresponding side part 8B, as is on this side of the anilox roller 5 whose drive is, and to this side no replacement of the interchangeable sleeve 11th he follows.

By pivoting the bearing receiver 55, as in Fig. 2 shown on the top left, results in the side part 8A, an opening of such a size that the sleeve 11 and sleeve 21, after the expander 42 were relaxed by turning back the sleeve 49, in the axial direction, ie along the axis of rotation A, of the Pull down the roller core 10 or 20 and remove it to the side. The installation of a new sleeve 11 and 21 is then carried out in the reverse order.

The FIG. 4 shows an alternative embodiment of the anilox roller 5, wherein the clamping is done not by mechanical, but by hydraulic clamping means 40. Again, the basic structure of the roller in the case of a fountain roller 6 is the same.

In the embodiment according to FIG. 4 the two spreading elements 43A, 43B are expandable by a hydraulic fluid, and designed for this purpose as pressure sleeves 60 which surround the two end portions of the roller core 10. Against the inner sides of the pressure sleeves 60 is a hydraulic volume, which is composed of a central bore 62 in the base body 12, of this outgoing transverse bores 63, and annular channels in the outer side of the base body 12, in which the transverse bores 63 open. Seals 64 between the annular channel and the inside of the respective pressure sleeve 60 prevent a pressure loss in the axial direction.

With a corresponding pressure in the hydraulic volume, a radial force on the pressure sleeves 60, so that they expand and press with their outer sides from the inside against the corresponding clamping surfaces 41.

The hydraulic piston 70 is seated in a bore 71 in the journal 12A of the roller core 10. The bore 71 is an extension of the central bore 62, and is in communication therewith , By means of a screw-threadably seated in a screw member 72, the hydraulic piston 70 can be adjusted along the bore 71, and so adjust the trapped hydraulic volume while building a corresponding hydraulic pressure.

Since the screw 72 as well as supported on the rear hydraulic piston 70 is seated in a longitudinal bore in the pin 12 A of the roller core 10, the screw 72 is easily accessible from the outside, so as to build up and adjust the hydraulic pressure.

At the other, the hydraulic piston 70 remote from the end of the roller core 10 is in turn provided with a collar 46 which forms an axial stop for the sleeve 11 of the roller. The stopper 46 is at Fig. 4 fastened by screwing, he also takes on a vent hole of the hydraulic system.

LIST OF REFERENCE NUMBERS

1 Cliché cylinder, pressure roller 1A cylinder core 1B cylinder sleeve 2 to be printed underlay 3 Backing roll 4 printing form 5 Anilox roller, applicator roller 6 dipping roller 7 paint tray 8A Side part of the printing unit 8B Side part of the printing unit 9 doctor 10 roll core 11 shell 12 body 12A spigot 12B spigot 13A Pressure bearing sleeve 13B Pressure bearing sleeve 20 roll core 21 thermowell 40 clamping means 41 clamping surface 42 spreading 43A spreader 43B spreader 45 Rifle 46 Federation 47 external thread 49 pressure sleeve 50 Sleeve base body 52A pivot bearing 52B pivot bearing 54 hinge 55 bearing seat 60 pressure sleeve 62 central hole 63 cross hole 64 poetry 70 hydraulic pistons 71 drilling 72 screw A axis of rotation

Claims (15)

Flexographic printing unit with a pressure roller (1) carrying at least one printing form (4), a counterpressure roller (3) and at least one applicator roller (5) transferring the ink directly to the printing form (4), characterized in that the applicator roller (5) consists of a Roll core (10) and a roller core (10) enclosing sleeve (11) composed, the outer shell is provided with a screening, and on its inner shell at least one clamping surface (41), against the clamping means (40) are clamped from the inside , wherein the clamping means (40) are part of the roller core (10). Flexographic printing unit with a pressure roller (1) carrying at least one printing form (4), a counterpressure roller (3), at least one applicator roller (5) transferring the ink directly to the printing form (4) and a fountain roller (6) upstream of the applicator roller (5), characterized in that the fountain roller (6) consists of a roller core (20) and a roller core (20) surrounding the immersion sleeve (21) having on its inner shell at least one clamping surface (41) against the clamping means (40) from the inside can be tensioned forth, wherein the clamping means (40) are part of the roller core (20). Printing unit according to Claim 1 or 2, characterized in that the clamping means (40) comprise at least one spreading device (42) which can be actuated from the inside against the clamping surface (41). Printing unit according to claim 3, characterized in that part of the spreading device (42) is at least one expanding element (43A, 43B) which can be expanded outwards. Printing unit according to claim 4, characterized in that components of the spreading device (42) a first, expandable to the outside spreading element (43A) at one end of the roller core (10, 20) and at least one further, expandable to the outside spreading element (43B) at the other end of the roller core (10, 20). Printing unit according to claim 5, characterized in that the spreading element (43A, 43B) by means of a longitudinal direction of the axis of rotation (A) adjustable pressure element, which exerts an axial pressure on the expansion element (43A, 43B) is mechanically expandable. Printing unit according to Claim 6, characterized by a threaded bush (49) which can be screwed onto an external thread (47) of the roller core (10, 20) as a pressure element. Printing unit according to claim 6 or 7, characterized by a longitudinally movable portion of the roller core (10, 20) longitudinally movable, cylindrical bushing (45) as an axial pressure transmitting pressure element. Printing unit according to claim 8, characterized in that the cylindrical bushing (45) is axially supported on the one hand with respect to the first expansion element (43A) and on the other hand with respect to the further expansion element (43B). Printing unit according to claim 1 or claim 2, characterized in that the roller core of the applicator roller (5) or the fountain roller (6) consists of a central body (12) and the longitudinally successively arranged and in the axial direction (A) against each other supporting components Threaded bushing (49), first expansion element (43A), further bushing (45) and further expansion element (43B), and that the further expansion element (43B) is axially supported against a collar (46) which is rigidly secured to the base body (12). is arranged. Printing unit according to claim 5, characterized in that the spreading elements (43A, 43B) are hydraulically expandable. Printing unit according to claim 11, characterized in that the spreading elements (43A, 43B) arranged on the roller core (10, 20), against the clamping surface (41) expandable pressure sleeves (60) whose inner side can be acted upon by a hydraulic fluid. Printing unit according to claim 11 or 12, characterized in that for adjusting and maintaining the hydraulic pressure of the roller core (10, 20) is provided with a hydraulic volume limiting the enclosed hydraulic piston (70) which sits in a bore (71) and along this bore ( 71) is adjustable. Printing unit according to one of the preceding claims, characterized in that the sleeve (11, 21) is in several parts and composed of an elongated sleeve body (50) and at least one pressure receiving sleeve (13A, 13B) inserted therein, wherein the pressure receiving sleeve (13A, 13B) extends only over a part of the length of the sleeve main body (50), and the clamping surface (41) is located exclusively on the pressure receiving sleeve (13A, 13B). Printing unit according to one of the preceding claims, characterized in that the roller core (10, 20) with its first end in a first side part (8A), and with its second end in a second side part (8B) is rotatably mounted, wherein the first side part ( 8A) around the pivot bearing (52A), and that the diameter of the opening for axially withdrawing the sleeve (11, 21) is larger than the outer diameter of the sleeve (11, 21).

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