EP3536506A1 - Ink jet printing apparatus - Google Patents

Abstract

An inkjet printing device includes a print bar and cleaning tape for wiping the print bar. There is a mechanism for generating a wiping movement (W) between the pressure beam and the cleaning belt, the wiping movement (W) having a first component (x) and a second component (y) perpendicular thereto. The wiping motion is thus multi-dimensional and may take the form of an elongated cycloid. As a result, a particularly thorough cleaning of a nozzle surface of the pressure bar is achieved.

Description

The present invention relates to a printing device for inkjet, comprising a printing bar and a cleaning tape for wiping the printing bar.

Print bars are used for page-wide printing. Often they are composed of a series of printheads. Each printhead has a nozzle plate and the nozzle plates together form the nozzle surface of the pressure bar. This nozzle surface is wiped with the cleaning tape from time to time, which is automated.

In DE 10028318 A1 there is described a printing machine having an ink jet printer whose nozzle surface is wiped with a cleaning tape that continuously passes the surface. The disadvantage is that this does not achieve a thorough cleaning of the nozzle edge. The nozzles opening into the nozzle surface have an inner edge on which ink residues can accumulate during cleaning. The prior art cleaning belt runs only in a single direction, which may be parallel to the printing material transport direction or may be transverse thereto. In this way, no thorough cleaning can be achieved.

The object of the invention is to provide a printing device with a cleaning tape with which the pressure bar is thoroughly cleaned.

This object is achieved by a printing device for inkjet, which comprises a pressure bar and a cleaning belt for wiping the pressure bar and is characterized in that a mechanism for generating a wiping movement between the pressure bar and the cleaning belt is present, wherein the wiping movement of a first component and a to vertical, second component has.

In the printing device according to the invention, the wiping movement is a multi-dimensional relative movement between the pressure bar and the cleaning belt. To produce this multi-dimensional wiping movement, the pressure bar can move relative to the cleaning belt or the cleaning belt can move relative to the pressure bar or both can move relative to each other. For example, the first direction or movement component can be generated by a movement of the pressure bar and the second directional and movement component, which is perpendicular to the first directional and movement component, can be generated by a movement of the cleaning belt.

Characterized in that the cleaning tape wipes, so to speak, across the nozzle surface, it captures each peripheral portion of the z. B. circular inner edge of each nozzle orifice. Through this thorough cleaning is reliably avoided that accumulate on the inner edge of ink residues.

Preferably, the multi-dimensional wiping movement follows a regular pattern of movement. In this case, the wiping movement can have, for example, a sinusoidal shape or the shape of an extended cycloid (English: prolate cycloid). The regular wiping pattern ensures uniform cleaning of the nozzle surface.

• Der Mechanismus kann so ausgebildet sein, dass er das Reinigungsband relativ zu dem Druckbalken bewegt, wobei das Reinigungsband die erste Komponente und auch die zweite Komponente der Wischbewegung ausführt.

Der Mechanismus kann ein Andrückelement zum Andrücken des Reinigungsbands an den Druckbalken aufweisen, wobei das Andrückelement zusammen mit dem Reinigungsband die zweite Komponente ausführt.
Das Andrückelement kann in einem Hilfsgestell gelagert sein und der Mechanismus kann eine Schwingeinrichtung aufweisen, die das Hilfsgestell hin- und herbewegt, um die zweite Komponente zu erzeugen.
Das Hilfsgestell kann in Parallelschwingen gelagert sein.
Die Schwingeinrichtung kann das Hilfsgestell hin- und herbewegen, um zur zweiten Komponente zusätzlich die erste Komponente zu erzeugen.
Das Hilfsgestell kann in einem Kreuzgelenk gelagert sein.
Der Mechanismus kann ein Kurbelgetriebe aufweisen, welches das Hilfsgestell hin- und herbewegt.
Der Mechanismus kann eine Spuleinrichtung zum Aufwickeln des Reinigungsbands aufweisen, wobei eine von der Spuleinrichtung erzeugte Vorschubbewegung des Reinigungsbandes die erste Komponente bildet.There are various training possible:

• The mechanism may be configured to move the cleaning belt relative to the pressure beam, wherein the cleaning belt performs the first component and also the second component of the wiping movement.

The mechanism may include a pressing member for pressing the cleaning tape against the pressure bar, wherein the pressing member performs the second component together with the cleaning tape.
The pressing member may be mounted in an auxiliary frame and the mechanism may include a swinging device that reciprocates the auxiliary frame to produce the second component.
The auxiliary frame can be mounted in parallel swing.
The vibrator may reciprocate the auxiliary frame to additionally produce the second component to the first component.
The auxiliary frame can be mounted in a universal joint.
The mechanism may include a crank gear which reciprocates the subframe.
The mechanism may comprise a winding device for winding up the cleaning belt, wherein a feed movement of the cleaning belt generated by the winding device forms the first component.

The pressure element may be formed as a pressure roller and be driven directly by a direct drive without the interposition of a transmission. For this purpose, a roll neck of the pressure roller axially aligned with a motor shaft of the direct drive, wherein the drive pin and the motor shaft can be connected to each other via a coupling.

The cleaning tape can be used without detergent for dry cleaning of the nozzle surface. Alternatively, the cleaning belt may be used for washing the nozzle surface using a detergent. For this purpose, the cleaning tape may be pre-moistened with the detergent. For this purpose, the cleaning device of the printing device may comprise a moistening device for the cleaning belt.

The cleaning tape may be a cleaning cloth with plastic cloth fibers. The cloth fibers may have a diameter which is 2 to 15 microns. The nozzle orifices in the nozzle surface may have a diameter which is 6 to 30 microns. The fiber diameter: nozzle diameter ratio can be from 1: 5 to 1: 2. The pile height of the fabric fibers can be 0.1 to 1.0 mm.

The cleaning device, to which the cleaning belt, the pressing element, the winding device and the auxiliary frame belong, can be designed as a removable unit from the printing press or cassette.

The winding device may comprise a first spool and a second spool, wherein the first spool serves as a supply spool for unwinding still clean cleaning tape and the second spool serves as a so-called dirty cloth spool for winding up after cleaning dirty cleaning belt.

Along the strip path, a first pair of friction rollers may be arranged between the first coil and the pressure element and a second pair of friction rollers between the pressure element and the second coil, each of the two pairs of friction rollers being driven by a separate motor in order to better control the movement of the cleaning belt ,

The first component of the wiping movement may be formed by the advancing movement of the cleaning belt, and the second component may be formed by a lateral oscillation of the pressing element. In this case, the feed movement and the lateral oscillation of one and the same motor can be driven. In order to couple the advancing movement and the lateral oscillation, the mechanism may comprise a gear, for example a bevel gear.
In the generation of the multi-dimensional wiping movement, the cleaning tape can be moved forward and backward in its longitudinal direction.

This movement of the cleaning tape can be superimposed by a transverse movement to produce the multi-dimensional wiping movement. To generate this transverse movement, the aforementioned auxiliary frame can be moved together with the pressure element and guided by the pressure cleaning belt in the transverse direction or alternatively the pressure element can be moved together with the guided by him cleaning tape relative to the auxiliary frame in the lateral transverse direction.

The drive system for generating the lateral transverse movement of the auxiliary frame may preferably be a crank mechanism or eccentric drive and may alternatively be a linear drive, a helical gear, a pneumatic cylinder or the like.

When the pressing member is formed as a pressure roller, this pressure roller may be either a crowned roller or a cylindrical roller.
The training as spherical roller is advantageous if the auxiliary frame is tilted or pivoted together with the spherical roller mounted therein for generating the transverse movement back and forth.
The design as a cylindrical roller is advantageous if the cylindrical roller mounted in the auxiliary frame oscillates relative to the auxiliary frame for generating the transverse movement. In this case, the cylindrical roller performs a linear vibration relative to the auxiliary frame in the direction of the axis of rotation of the cylindrical roller.

Instead of being a pressure roller, the pressure element can also be designed as a non-rotating pressure element, for example as a profile bar over which the cleaning belt runs.

There may be a sensor that monitors that the cleaning tape does not run off the side of the pressing element. The sensors can give a warning signal if the cleaning belt is no longer correctly centered on the pressure element.

The advancing movement of the cleaning belt during cleaning may be continuous or intermittent at intervals.
Preferably, the feed direction of the cleaning belt is parallel to the longitudinal direction of the pressure beam.
Alternatively, the advancing direction of the cleaning belt may be perpendicular relative to the longitudinal direction of the pressure beam, wherein the multi-dimensional wiping movement is generated by movement of the pressure beam in its longitudinal direction with the advancing movement of the cleaning belt in coordination with each other and are superimposed.

Figur 1a:

eine Frontalansicht eines Druckbalkens und einer Reinigungseinrichtung zum Abwischen des Druckbalkens,

Figur 1g:

eine Seitenansicht des Druckbalkens und eines Andrückelements der Reinigungseinrichtung,

Figur 2:

eine Seitenansicht des Druckbalkens und eines Hilfsgestells mit Teilen der Reinigungseinrichtung,

Figuren 3a bis 3c:

verschiedene Bewegungsformen einer von der Reinigungseinrichtung erzeugten Wischbewegung,

Figur 4a:

eine Frontalansicht einer Spuleinrichtung der Reinigungseinrichtung,

Figur 4b:

eine Schnittdarstellung gemäß der Schnittlinie IVb-IVb in Figur 4a,

Figur 5:

eine Draufsicht auf eine Modifikation der Reinigungseinrichtung und

Figur 6:

eine Seitenansicht der Modifikation.

Further developments will become apparent from the following description of exemplary embodiments and the accompanying drawings, in which:

FIG. 1a

a front view of a pressure bar and a cleaning device for wiping the pressure bar,

FIG. 1g:

a side view of the pressure beam and a pressing member of the cleaning device,

FIG. 2:

a side view of the pressure beam and an auxiliary frame with parts of the cleaning device,

FIGS. 3a to 3c:

various forms of movement of a wiping movement generated by the cleaning device,

FIG. 4a

a front view of a winding device of the cleaning device,

FIG. 4b:

a sectional view along the section line IVb-IVb in FIG. 4a .

FIG. 5:

a plan view of a modification of the cleaning device and

FIG. 6:

a side view of the modification.

In the FIGS. 1a to 6 are mutually corresponding elements and components designated by the same reference numerals.

FIG. 1a shows a printing device from a direction of the printing material transport direction corresponding viewing direction. The printing device comprises a print bar 1 for page wide inkjet printing with a nozzle surface 2, from the nozzles of which ink is ejected during printing. The pressure bar 1 comprises a series of print heads, which extends over the entire width of the sheet or web-shaped substrate. Under the pressure bar 1, a cleaning device is arranged, which comprises a cleaning tape 3 for wiping the nozzle surface 2.

The cleaning device further comprises a pressing element 4, which holds the cleaning tape 3 in contact with the nozzle surface 2 during wiping. A winding device 5 with a first coil 6 and second coil 7 also belongs to the cleaning device. The first coil 6 is used to unwind clean cleaning tape 3 and the second coil 7 for winding dirty cleaning tape 3. For driving a feed movement V of the cleaning tape 3, one or more pairs of friction rollers 8 may be present. As indicated in the drawing with different signs, the direction of the feed motion V can change during cleaning.

FIG. 1b shows parts of the printing device from a viewing direction which is transverse to the printing material transport direction. The pressing member 4 is mounted in an auxiliary frame 9 via a suspension 10, which compensates for a lifting height H, which occurs in a lateral pivoting of the auxiliary frame 9. The suspension 10 acts on roll neck of the pressure element 4 or on pivot bearings, in which sit the roll neck.

The pressing element 4 has a roller body which is crowned or barrel-shaped. The spherical roller body has a cylindrical central portion and then frusto-conical end portions with chamfers. The cylindrical central portion is axially longer than the sum of the width of the nozzle surface 2 and twice the amplitude of the lateral component y of the wiping movement W. The cleaning tape 3 is in FIG. 1b not shown.

FIG. 2 shows one of the FIG. 1b corresponding side view, but with more components of the cleaning device. The auxiliary frame 9 is pivotally mounted in a main frame 11 via a pair of parallel rockers 12. The pivoting movement of the auxiliary frame 9 and thus of the cleaning belt 3 in the lateral direction with respect to the pressure beam 1 is driven by a drive system comprising a motor M1 and a crank mechanism 13. By pivoting the auxiliary frame 9 back and forth, the cleaning tape 3 performs the component y of the wiping movement W from.

During the wiping movement W, the cleaning belt 3 is in continuous contact with the nozzle surface 2 in a contact which is in FIG. 2 not shown. The winding device 5 and each pair of friction rollers 8 and a gear transmission 14, via which a motor M2 drives the feed movement V of the cleaning belt 3, are also mounted in the auxiliary frame 9. The auxiliary frame 9, the parallel rockers 12, the crank mechanism 13 and the motor M1 are components of a vibrating device 15. This oscillating device 15 generates the component y of the wiping movement W. The feed motion V corresponds to the component x of the wiping movement W. From the superposition of the two components x , y results in the multidimensional wiping movement W, whose shape corresponds to the variants in the subsequent ones FIGS. 3a to 3c can correspond.

In FIG. 3a a diagram is shown whose abscissa shows the component x and its ordinate the component y of the wiping movement W. In this variant, the wiping movement W has a sinusoidal shape.

FIG. 3b shows a diagram with a variant of the wiping movement W, in which this has the shape of an elongated cycloid.

Figure 3c also shows a wiping movement W in the form of an elongated cycloid, with their turns or loops overlap.

In the FIGS. 4a and 4b the winding device 5 is shown in detail. Each coil 6, 7 is equipped with a freewheel 18, wherein the one freewheel 18 acts blocking in a clockwise direction and the other freewheel 18 counteracts blocking in the counterclockwise direction. The two freewheels 18 are thus opposite to each other or counteracting each other. A motor M2 drives the coils 6, 7 via two gear trains, which branch off from one another in a motor pinion. To the gear train includes the gear 20, which is connected via the one freewheel 18 with the coil 7. Depending on the direction of rotation of the motor M2 locks the one freewheel 18 and slips the other freewheel 18 through. It is thereby achieved that the feed movement V of the cleaning belt 3 can take place forward and backward or in the positive and negative directions.

In the embodiment described above, the component x of the wiping movement W is generated solely by the feed movement V of the cleaning tape 3.

In the in the FIGS. 5 and 6 As shown modification, the component X is generated by a vibration of the auxiliary frame 3 or by a superposition of this vibration with the feed motion V. The motor M1 drives the two mutually orthogonal oscillations of the auxiliary frame 9, both the vibration to produce the component x and the vibration to produce the component y. Here, the auxiliary frame 9 is not stored in the parallel rocker, but connected via a universal joint 16 with the main frame 11. The crank gear 13 generates the vibration corresponding to the component x about the one axis of the universal joint 16, and another crank gear 21 generates the vibration corresponding to the component y about the other axis of the universal joint 16.

The two crank gears 13, 21 are connected to each other via a bevel gear 17, wherein the crank gear 13 eccentrically engages the one bevel gear of the bevel gear 17 and the crank gear 21 acts eccentrically on the other bevel gear. In the modification, the motor M2 is not required because the motor M1 also generates the feed motion V of the cleaning belt 3. For this purpose, the shaft of the bevel gear, which is arranged coaxially with the motor M1, connected to the coil 7 for winding. The unwinding reel 6 can be braked by a brake 19. The brake 19 is advantageous to build in that portion of the cleaning tape 3, which lies between the coils 6 and 7 and runs over the pressing member 4, a beneficial for cleaning tension. In the modification, the auxiliary frame 9, the universal joint 16, the motor M1, the crank gears 13, 21 and the bevel gear 17 components of the vibrating device 15th

In all embodiments described above, the inner nozzle edges are swept by the cleaning tape 3 from all directions during cleaning, which is ensured by the multi-dimensional wiping movement W.

LIST OF REFERENCE NUMBERS

1

pressure beam

2

die face

3

cleaning tape

4

pressing element

5

winding device

6

Kitchen sink

7

Kitchen sink

8th

pair of friction rollers

9

subframe

10

suspension

11

main frame

12

parallel rocker

13

crank mechanism

14

gear transmission

15

oscillating device

16

Universal joint

17

bevel gear

18

freewheel

19

brake

20

gear

21

crank mechanism

H

Lifting height

M1

engine

M2

engine

V

feed motion

W

swipe

x

component

y

component

Claims (10)

Printing device for inkjet, comprising a pressure bar (1) and a cleaning belt (3) for wiping off the pressure bar (1),
characterized,
in that a mechanism for generating a wiping movement (W) is present between the pressure bar (1) and the cleaning belt (3), the wiping movement (W) having a first component (x) and a second component (y) perpendicular thereto. Printing device according to claim 1,
characterized,
in that the mechanism moves the cleaning belt (3) relative to the pressure beam (1), the cleaning belt (3) executing the first component (x) and the second component (y). Printing device according to claim 1 or 2,
characterized,
that the mechanism comprises a pressure element (4) for pressing the cleaning tape (3) to the pressure beam (1), wherein the pressing element (4) together with the cleaning tape (3), the second component (y) executes. Printing device according to claim 3,
characterized,
in that the pressing element (4) is mounted in an auxiliary frame (9) and the mechanism has an oscillating device (15) which moves the auxiliary frame (9) back and forth in order to produce the second component (y). Printing device according to claim 4,
characterized,
that the auxiliary frame (9) is mounted in parallel rockers (12). Printing device according to claim 4,
characterized,
in that the oscillating device (14) reciprocates the auxiliary frame (9) in order to additionally produce the first component (x). Printing device according to claim 6,
characterized,
that the auxiliary frame (9) is supported in a universal joint (16). Printing device according to one of claims 4 to 7,
characterized,
in that the mechanism has at least one crank mechanism (13, 21) which reciprocates the auxiliary frame (9). Printing device according to one of claims 1 to 5,
characterized,
in that the mechanism has a winding device (5) for winding up the cleaning belt (3), wherein a feed movement (V) of the cleaning belt (3) generated by the winding device (5) forms the first component (x). Printing device according to one of claims 1 to 9,
characterized,
in that the wiping movement (W) has a sinusoidal shape or the shape of an elongated cycloid.

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