EP1531043A1 - Process and device for moving a doctor blade - Google Patents

Abstract

The doctor (24) displacement process for a doctor blade (26) against the cylinder (10) of a printing press involves moving the doctor blade at the rate of 0-0.01 m/sec during most of the printing process, using a displacement device (38), which moves the blade along its longitudinal axis in the manner specified for the process.

Description

The invention relates to a method for moving a cylinder to a Pressing machine employed doctor blade in the direction of the longitudinal axis of the Doctor blade and a device for carrying out the method.

In printing presses doctor blade metering devices are generally added used, the surface of a rotating cylinder, such as the impression cylinder, unravel with the aid of a doctor blade. For example, such has one Squeegee device in a gravure press the function that polished smooth Surface of the gravure cylinder after coloring and before the actual Clean off the printing process so that the printing ink is only in the printing, recessed areas of the printing cylinder surface remains.

In conventional printing presses, the doctor blades are usually made thin sheet steel made of hardened or unhardened spring steel. One to the Surface of the printing cylinder or the anilox roller employed one Doctor blade is subject to significant wear. To the service life of the doctor blade, the doctor blade is in an oscillation in offset in its longitudinal direction, so that the wear of the doctor blade itself distributed as possible. The frequency of such oscillation may be, for example depending on the production speed 1 Hz or more, and the Stroke of the oscillation can be up to 40 mm, for example. True will be by an oscillation of the doctor blade of the wear of the doctor blade locally distributed, but it is still relatively often necessary, a worn doctor blade replaced. This requires a standstill of the printing press.

To further reduce the wear of the doctor blade, doctor blades are used used, which ceramizes on its side facing the pressure cylinder wear side are. The life of the doctor blade is thus a multiple elevated.

It is known from the Applicant's European Patent Application EP 1 362 696 to vibrate the doctor blade at a frequency that in the acoustic range or in the ultrasonic range. This measure serves to remove impurities from the gravure cylinder. The stroke of the vibration movement can be less than 0.2 mm.

Although on the one hand a lateral oscillation of the doctor blade is desired to but can reduce uneven wear of the doctor blade the oscillation also have a negative effect on the printed image, since through Differences in speed of the doctor blade slightly different Amounts of color in the wells of the printing cylinder can result, the Differences in ink application lead to the substrate web. Especially the difference between an area where the doctor blade with a uniform speed moves, and an area where a Reversal of the direction of movement of the doctor blade takes place on the printed image be detectable. Since the frequency of oscillation of the doctor blade often with The speed of the pressure cylinder is coupled, for example, at a High quality multicolor print the movement pattern of different doctor blades designed differently, so that the deviations of the individual colors do not sum up. With particularly high-quality multicolor printing can nevertheless the different, occurring during the oscillation of the doctor blade Speeds. Movement directions and turns the print image negative influence.

The object of the invention is a method for moving one to a cylinder to create a printing machine employed doctor blade, with the at as even and as little as possible wear of the doctor blade achieve the highest possible print quality, and a printing press to create the method.

This object is achieved by a method of the aforementioned Kind of solved, in which the sliding movement of the doctor blade is so kind, that during the overwhelming duration of the printing operation, the shift speed of the doctor blade in the range of 0 to 0.1 m / s, in particular of 0 to 0.01 m / s. Furthermore, this object is achieved by a printing press Claim 7 solved.

Preferably, the displacement speed of the doctor blade during the overwhelming duration of printing operation in the range of zero to 1 mm / s, especially preferably in the range of zero to 0.1 mm / s, in particular in the range from zero to 0.01 mm / s.

The shift speeds specified for the majority of the printing operation may apply in particular to periods of time Proportion of 90%, in particular 99% of the duration of the printing operation.

If during the majority of the printing operation the doctor blade is moved with a low shift speed or even stops, can negatively affect the movement of the doctor blade on the Print quality compared to a conventional, faster oscillation of the Doctor blade can be significantly reduced. The smaller one deviating from zero Shift speed is, the less affects the sliding movement on the printed image. Nevertheless, in the case of a longer lasting, slow moving movement of the doctor blade or at intervals Moving movement achieved that the doctor blade in the course of time by one Stroke of several millimeters is shifted, so that the wear of the doctor blade distributed over the stroke length.

The invention combines the prevention of uneven wear of the Doctor blade with the possibility of a particularly high print quality, da during standstill or very slow movement of the doctor blade a particularly uniform application of ink results on the substrate.

Advantageous embodiments of the invention will become apparent from the dependent claims.

In a first embodiment of the method, the displacement movement of the Doctor blade time divided into movement and stoppage sections, and During printing, the duration of the standstill sections predominates. Especially The duration of the movement sections may be less than 10 percent of the time Duration of the standstill sections amount, preferably less than 1 percent. she can also be significantly lower. The duration of the downtime sections is preferably to be chosen so that during standstill of the doctor blade no noticeable uneven wear of the doctor blade results. In this embodiment, the uniformity and thus the quality of the print image during the standstill of the doctor blade especially high.

In a printing press, where the substrate is pulled off a roll and / or wound on a roll, is known to cause a role change to temporarily produce scrap during the current printing operation becomes. This is the case, for example, if one is automatic Reel splice produced the substrate web through the printing unit runs or when a web section is printed, which later on an automatic Change the take-up roll must be severed. Prefers Therefore, in the method according to the invention, the movement sections when moving the doctor blade time chosen so that they with the production of committee. The disturbances of the printed image, the caused by the movement of the doctor blade, then affect the quality of the print result is not, since it together with the already incurred Committee be eliminated.

The displacement movement of the doctor blade is preferably automatically with the Reel changes synchronized.

In a second embodiment of the method is the displacement movement a periodic back and forth movement with a period of at least 10 seconds, in particular at least 1 minute, preferably at least 10 mins. Such a sliding movement can during the printing operation be carried out continuously and reduces the impairment the print image against a faster oscillation of the doctor blade clear. With appropriate wear resistance of the doctor blade, the period can also be much higher and be for example 1 hour. Also in the second embodiment, the described negative influence the squeegee movement on the printed image greatly reduced, while still a nonuniform Wear is prevented.

In both Ausführungsförmen the method of the sliding movement a vibratory movement with a frequency of at least 1 Hz, in particular at least 5 Hz, be superimposed. It can be during this vibration movement It is also an acoustic vibration or an ultrasonic vibration act. The vibratory movement is preferably in the direction of the longitudinal axis executed the doctor blade. On the one hand, it serves to remove impurities to remove the depressions of the cylinder or to detach from the doctor blade, as described in Applicant's European Patent Application EP 1 362 696 is. In particular, in the second embodiment, the vibration movement is used but also to it. Differences in the effectiveness of the doctor blade due to a periodic reciprocation occurring standstill occur during the reversal of the direction of movement. The movements of the doctor blade occurring during the vibration apply not as part of the "sliding movement" in the context of the invention, and the claim 1 specified speed limits affect only the pure displacement movement without consideration of the vibration.

The subject of claim 7 is a printing machine with a squeegee device, the one against a cylinder engagable doctor blade and a displacement device for moving the doctor blade in the direction of the longitudinal axis of the doctor blade, wherein the displacement device is formed is a method for moving the doctor blade attached to the cylinder To carry out according to one of the claims 1 to 4. The displacement device can be designed to semi-or fully automatic process perform. The printing press has the description of the process stated advantages.

In a preferred embodiment, the doctor device of the printing machine an oscillator for generating a vibratory movement of the doctor blade on, and the displacement device and the oscillator are designed to to carry out a method according to one of the claims 1 to 4, at the sliding movement a vibratory movement with a frequency of at least 1 Hz, in particular at least 5 Hz, superimposed.

In a particularly preferred embodiment of the printing machine that is Doctor blade ceramized on its wear side. This allows during the sliding movement of the doctor blade a long duration of a standstill section or a periodic float with one extra large period without causing uneven wear of the doctor blade comes.

In the following preferred embodiments of the invention are based on explained the drawing.

Figur 1

eine schematische Ansicht einer Tiefdruckmaschine;

Figur 2

einen schematischen Schnitt längs der Linie II - II in Figur 1;

Figur 3

eine schematische Teilansicht der Tiefdruckmaschine mit einem Aufwickler;

Figur 4

ein schematisches Diagramm einer Verschiebebewegung mit Bewegungs- und Stillstandsabschnitten;

Figur 5

ein schematisches Diagramm einer periodischen Hin- und Herbewegung;

Figur 6

eine schematische Ansicht einer Tiefdruckmaschine mit einer Rakelvorrichtung mit einem Oszillator; und

Figur 7

ein schematisches Diagramm von Abschnitten einer periodischen Hin- und Herbewegung, der eine Vibrationsbewegung überlagert ist.

Show it:

FIG. 1

a schematic view of a gravure printing machine;

FIG. 2

a schematic section along the line II - II in Figure 1;

FIG. 3

a schematic partial view of the gravure printing machine with a winder;

FIG. 4

a schematic diagram of a sliding movement with movement and standstill sections;

FIG. 5

a schematic diagram of a periodic reciprocation;

FIG. 6

a schematic view of a gravure printing machine with a doctor device with an oscillator; and

FIG. 7

a schematic diagram of sections of a periodic reciprocation, which is superimposed on a vibrational motion.

The gravure printing machine shown in FIG. 1 comprises a gravure cylinder 10, an applicator roller 12 and a impression roller 14 rotatably between side parts 16, 18 of a machine frame are mounted. Associated drive and control devices have not been shown here, as they are for the understanding of the invention are not essential.

The application roller 12 is at its upper apex with the gravure cylinder 10 in contact and dives with its lower apex in a paint tray 20th a, as can be seen more clearly in Figure 2. The applicator roller 12 thus decreases Ink from the ink tray 20 and transfers it to the peripheral surface of the gravure cylinder 10, which rotates in the direction of arrow in Figure 2 and the ink on a printing material 22 transmits, between the impression roller 14 and passes through the gravure cylinder and through the impression roller against the Gravure cylinder is pressed.

The gravure cylinder 10 is associated with a doctor device 24. This squeegee device is formed in a known manner by a doctor blade 26, the a holder 28 is attached. The holder is mounted on a shaft 30 which extends between two levers 32, 34 extends. The lower ends of the levers 32, 34 sit on a rotatable shaft 36, with which the entire doctor device 24th so can pivot against the circumference of the gravure cylinder, that its surface is doctored off with the cutting edge of the doctor blade 26. In this way is the recorded by application roller 12 ink from the smooth, not ducking surface areas of the gravure cylinder 10 removed so that the Printing ink remains only in the recessed areas that the printed image produce on the substrate web 22.

On the lever 34, a displacement device 38 is arranged, with which the holder 28 and thus the doctor blade 26 in the direction of the longitudinal axis of the doctor blade relative to the levers 32, 34 can be moved, as by a Double arrow is indicated in Figure 1. The displacement device 38 forms Thus, a transverse thrust device, the movement of the blade of the doctor blade 26 relative to the gravure cylinder 10 in the cross-machine direction the printing material web 22, that is generated in the axial direction of the gravure cylinder. Instead of the displacement device 38 may also be a displacement device be provided, which the entire doctor device 24 together with the levers 32, 34 shifts in the specified direction.

FIG. 2 shows a ceramic layer 40 on the underside of the doctor blade 26. by the wear of the doctor blade 26 by the contact with the rotating Gravure cylinder 10 is reduced.

Figure 3 shows that the substrate web 22 after printing in the gravure printing machine via deflection rollers 42 and a dancer roller 44 on a Aufwikkelrolle 46 is wound up. A full take-up roll can in a known manner be replaced automatically or manually by a new coil 48, the then forming the interior of the next take-up roll. The storage of the pulleys 42 and the take-up roll 46 and associated facilities of the Rewinder has not been shown here as it is for the understanding of Invention are not essential.

FIGS. 4 and 5 show two different displacement movements of the doctor blade 26 outlined by the displacement device 38 of the doctor device 24 can be effected. The sliding movement takes place in each case Direction of the longitudinal axis of the doctor blade instead. Indicated is one in each case Time course in the direction of the sliding movement varying position of the doctor blade 26. To differences between the different moves be clear, the diagrams of Figures 4 and 5 and the figure 7 described below is not shown in relation to each other.

Figure 4 illustrates a sliding movement of the doctor blade 26, the time is subdivided into movement sections 50 and standstill sections 52. there the duration of the stoppage sections 52 is at least 100 times the duration of the movement sections 50. During a movement section 50, the doctor blade 26 by a certain amount in the direction of Moved longitudinal axis of the doctor blade. In Figure 4 are two movement sections 50, in which the doctor blade 26 in each case in the same Direction and by the same amount, for example, 1 mm, is moved. After the doctor blade 26 during several movement sections 50 to is moved to a fixed position, finds a reversal of the direction of movement instead of. It may be the amount by which the doctor blade during the other movement sections is moved, be varied.

Notwithstanding the example shown in Figure 4 can also during the maintenance the direction of movement is a variation of the amount to which the doctor blade is moved during a movement section 50 done. To the highest possible uniformity of wear of the doctor blade 26th To ensure it is advantageous to set the amounts by which the doctor blade is to vary so that once occupied by the doctor blade Position is taken again after as long a time as possible.

The movement portions 50 coincide with the change of the take-up roll 46 together. During the standstill sections 52, a Aufwikkelrolle 46 wound. A sensor, not shown, detects the radius of the roll on the take-up roll 46 and solves when a roll change is required, the Movement section 50 off. The actual role change is then with a triggered such a time delay that the printing material when changing roles is severed approximately at the point that at the time of the movement section 50 was printed. If by the movement of the doctor blade 26 an impairment of the printed image is done, the fault is thus in one Section of the printing material web, which is the end of the old take-up reel or forms the beginning of the new take-up roll and later anyway as a committee Will get removed.

Figure 5 illustrates the sliding movement according to another embodiment. The displacement movement here is a periodic reciprocation with a period of one hour. The stroke of the oscillation is for example ± 20 mm. The speed of movement of the doctor blade 26 is therefore in the range of 0 to 0.04 mm / s. This very low displacement speed at most affects the print image to a very small extent. It Other forms of oscillation are conceivable, for example, a triangular wave.

A further improvement of the printed image is explained by one of the following Vibratory movement, the sliding movement of the doctor blade 26th is superimposed reached.

Figure 6 shows a comparison with Figure 1 modified gravure printing machine, in which the shaft 30 between the displacement device 38 and the holder 28 an oscillator 54 is inserted, the holder 28 and thus also the doctor blade 26th in high-frequency vibrations in the direction parallel to the axis of the gravure cylinder 10, ie parallel to the direction of displacement of the doctor blade 26, added. The oscillator 54 thus forms a further transverse thrust device, the generates a vibrating movement of the blade of the doctor blade 26, the Displacement movement is superimposed. The frequency of the vibration movement is in the ultrasonic range, so that the vibration vibrations of the doctor blade 26th have the shape of running ultrasonic waves that are opposite to each other Spread the end of the doctor blade and there through one between the lever 32 and the holder 28 inserted damper 56 are absorbed.

The frequency can also be significantly lower, and the oscillator 54 can for example, be an acoustic vibrator. Also an even lower one Frequency of the vibration movement is conceivable. The stroke of the vibration movement can be very small, for example, it can be less than 0.2 mm.

Figure 7 illustrates two portions of a translational movement of the doctor blade 26 according to Figure 5, which is superimposed on a vibrational movement. In one Section 58 of the sliding movement changes the middle position of the doctor blade 26 gradually, while the doctor blade 26 while a vibration with much lower stroke around the middle position performs. In a second Section 60, a direction reversal of the displacement movement takes place. The superimposed vibration movement causes here that also at the reversal point the sliding movement no temporary stoppage of the doctor blade 26th results. By the superimposed vibration movement shown in Figure 7 is opposite the displacement movement shown in Figure 5 without superimposed vibration movement a further increase in print quality or, for the same quality, a higher displacement speed of the doctor blade possible.

The embodiments shown each relate to a gravure printing machine. However, the invention is not only in gravure printing machines, but also in applicable to other printing presses.

Claims (9)

Method for displacing a doctor blade (26) attached to a cylinder (10) of a printing machine in the direction of the longitudinal axis of the doctor blade (26), characterized in that the displacement movement of the doctor blade (26) is such that during the predominant duration of the printing operation Shifting speed of the doctor blade (26) in the range of zero to 0.1 m / s, in particular from zero to 0.01 m / s. Method according to Claim 1, characterized in that the displacement movement of the doctor blade (26) is subdivided into movement (50) and standstill sections (52) and that during the printing operation the duration of the stationary sections (52) predominates, in particular that the duration of the movement sections (50) is less than 10% of the duration of the shutdown periods (52). Method according to Claim 2, characterized in that the movement sections (50) are each in operating phases in which rejects are printed. A method according to claim 1, characterized in that the sliding movement is a periodic reciprocating movement with a period of at least 10 seconds, in particular at least 1 minute. Method according to one of the preceding claims, characterized in that the sliding movement is superimposed on a vibratory movement with a frequency of at least 1 Hz, in particular at least 5 Hz. Method according to Claim 5, characterized in that the vibratory movement is carried out in the direction of the longitudinal axis of the doctor blade (26). Printing machine with a squeegee device (24) which has a doctor blade (26) which can be turned against a cylinder (10) and a displacement device (38) for displacing the doctor blade (26) in the direction of the longitudinal axis of the doctor blade (26), characterized in that Displacement device (38) is designed to carry out a method for displacing the doctor blade (26) attached to the cylinder (10) according to one of Claims 1 to 4. Printing machine according to claim 7, characterized in that the doctor device (24) has an oscillator (54) for generating a vibratory movement of the doctor blade (26) and the displacement device (38) and the oscillator (54) are adapted to a method according to claim 5 or 6. Printing machine according to claim 7 or 8, characterized in that the doctor blade (26) is ceramized on its wear side.

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