EP2127874B1 - Method for operating a printing press - Google Patents

Abstract

The method involves arranging a clutch (21) between a motor (11) and a roller (6), and controlling the motor by a control device (37) such that another roller (5) is rotated at a rotational speed, which is in constant relation with a rotational speed of the former roller. The rollers are rotatively driven by the motor in an operating mode i.e. maintenance mode, for transferring torque from the motor to the former roller over the clutch. Current of the motor is periodically increased in a print operating mode by the control device.

Description

The present invention relates to a method for operating a printing press in a print mode and another mode of operation, in particular a maintenance mode.

The maintenance of printing presses between printing jobs involves changing the printing plates and washing the inking units. A simultaneous implementation of the plate change and the Farbwerkswaschens is aimed at shortening the maintenance. To enable simultaneous operation, the plate cylinder is driven by the main motor of the printing press and the inking unit by a separate motor. In EP 1167026 B 1 is a printing machine with the required motors described.

A long-known problem with printing machines is that of the lifter. The cause of the lifter stroke is an existing during the impact of the vibrating roller on the distributor roller between the peripheral speeds of these two rollers difference. By this difference, torsional vibrations are caused, which are transmitted from the distributor roller to subsequent rollers and cylinders and reduce the print quality. Various measures have already been proposed to solve the problem.

One measure consists in a separate motor for the distributor roller, as z. In EP 0475120 A1 and DE 19715614 A1 has been proposed.

Another measure consists of the friction roller associated clutch, via which the drive roller is driven rotatively in the washing operation. In printing operation, the clutch is open and the friction roller is fricatively driven by a neighboring roller. This measure is in DE 4445964 B4 described.

In GB-A-1472654 is a printing machine with a ink fountain roller and a distributor roller described. The ink fountain roller and the distributor roller each have their own motor.

The motors are controllable such that the speed behavior of the ink fountain roller and the distributor roller is accurately adjusted to the machine speed.

In EP-A-0699524 is a printing machine described in which all the form cylinder of a printing unit are driven by a separate electric motor. The form cylinder are not in mechanical drive connection with each other.

In DE 19520841 A1 a printing machine is described with a color dampening roller, which is driven by a separate drive motor in terms of their peripheral speed with difference to that of a forme cylinder.

The invention has for its object to provide an improved method for operating a printing press. In particular, it is the object of the invention to specify a method which improves the shortening of the maintenance time and / or with regard to the reduction of the lifter stroke.

This object is achieved by a method having the features of claim 1. In the method according to the invention, a printing press is operated in a printing operating mode and another operating mode. In the print mode of operation, a lift roller is periodically brought into contact with a first roller of an inking unit of the printing press. In addition, in the printing mode of operation, the first roller is rotationally driven by a first motor and a second roller of the inking unit is rotatively driven by a second motor. In the pressure mode of operation, no torque is transferred from the first motor to the second roller via a clutch disposed between the first motor and the second roller. In the printing operation mode, the first motor is controlled by a control device such that the first roller rotates at a speed that is in a constant ratio with a speed of the second roller. In the method according to the invention, in the other operating mode, the first roller and the second roller are rotationally driven by the first motor, and torque is transferred from the first motor to the second roller via the clutch.

In the dependent claims advantageous developments of the method according to the invention are mentioned.

In a development, the other operating mode is a maintenance mode, for. B. a cleaning mode. In this cleaning or maintenance mode, the inking unit can be washed.

In a further development, the motor current of the first motor is increased periodically in the pressure operating mode by the control device. These Motorstromerhöhungen can each shortly before the impact of the squeegee roller on the first roller, so that the circumferential speed of the first roller is kept constant despite the impingement by the motor current increases.

In a further development, the clutch is rotated while maintaining a backlash of the clutch in the pressure operating mode. In this case, in the pressure operating mode, the backlash between a first coupling half and a second coupling half of the coupling can be maintained in the circumferential direction. For this purpose, in the printing operating mode, the first coupling half can be driven in rotation by the first motor and at the same time the second coupling half can be driven by the second motor. The two coupling halves can be driven so coordinated that none of the two coupling halves entrains the other and seen in the circumferential direction is a dead path or a game between a driving surface of the first coupling half and a driving surface of the second coupling half.

To carry out the method according to the invention or one of the further developments, a lithographic offset printing machine for printing sheets can be used.

Functionally and structurally advantageous developments of the invention are also described in the following embodiment and shown in the accompanying drawings.

Figur 1

eine Druckmaschine mit einem Farbwerk, welches Walzen und einen Antriebsmechanismus zum Antreiben der Walzen aufweist,

Figur 2

eine schematische Darstellung des Antriebsmechanismus, der Kupplungen zum Übertragen von Drehmomenten aufweist,

Figur 3a

eine der Kupplungen in einer während des Druckbetriebs eingenommenen Drehwinkelstellung zweier Kupplungshälften relativ zueinander, in der keine Drehmomentübertragung erfolgt,

Figur 3b

die Kupplung aus Figur 3a in einer während eines Reinigungsmodus des Farbwerks eingenommenen Drehwinkelstellung, in der ein Drehmoment von der ersten auf die zweite Kupplungshälfte übertragen wird, und

Figur 4

ein Diagramm, welches periodische Motorstromerhöhungen eines Motors des Farbwerks zeigt, die im Druckbetrieb erfolgen.

In this shows:

FIG. 1

a printing machine with an inking unit, which has rollers and a drive mechanism for driving the rollers,

FIG. 2

a schematic representation of the drive mechanism having clutches for transmitting torques,

FIG. 3a

one of the clutches in a rotational angular position of two coupling halves, which is assumed during the printing operation, relative to one another, in which no torque is transmitted,

FIG. 3b

the clutch off FIG. 3a in a rotational angular position assumed during a cleaning mode of the inking unit, in which a torque is transmitted from the first to the second coupling half, and

FIG. 4

a diagram showing periodic motor current increases of an engine of the inking unit, which take place in the printing operation.

FIG. 1 shows a detail of a printing press 1 for printing on sheets. The detail shows a printing unit for offset printing. The printing unit comprises an impression cylinder and a blanket cylinder, which are not shown in the drawing. Furthermore, it comprises a printing form cylinder 2, an unspecified dampening unit for moistening the printing forme cylinder 2 and an inking unit 3 for coloring the printing forme cylinder 2. The inking unit 3 is a lifting inking unit and comprises an ink fountain with a ink fountain roller 4, a first roller 5, a plurality of second rollers 6 and unspecified further rollers, including transfer rollers and applicator rollers. The second rollers 6 are rotationally driven by gears, which are arranged coaxially with the second rollers 6 and rotatably connected. These gears are components of a transmission 23 (see. FIG. 2 ). Furthermore, the inking unit 3 comprises a lifting roller 7, which oscillates back and forth between the ink fountain roller 4 and the first roller 5 and alternately comes into contact with the two rollers 4, 5. A spraying device 8 for supplying detergent and rinse water into the inking unit 3 and a squeegee device 9 for subsequently removing the detergent-ink mixture from the inking unit 3 are provided for a cleaning mode.

FIG. 2 shows that a first motor 11 for rotatably driving the first roller 5 is connected to the latter. In the embodiment shown, the first motor 11 is arranged coaxially with the first roller 5, so that the motor shaft of the first motor 11 and the geometric axis of rotation of the first roller 5 are aligned. A second motor 12 is connected to these rollers 6 for rotationally driving the second rollers 6 via the aforementioned gear 23. The motors 11, 12 are electric motors. The second motor 12 is the so-called main drive of the printing machine 1 and drives, among other things, the printing form cylinder 2 (see. FIG. 1 ) rotatively. The first motor 11 is a separate motor and can be controlled by means of an electronic control device 37 as a function of the second motor 12. Components of the transmission 23 are in addition to the gears and a first clutch 21 and a second clutch 22nd

The first roller 5 is arranged between the first motor 11 and the first clutch 21, so that a torque generated by the first motor 11 can be transmitted to the first clutch 21 via the first roller 5. The first clutch 21 is disposed between the first roller 5 and a coaxial with the first roller 5 gear of the transmission 23 and connects this gear with the first roller 5 temporarily rotationally fixed when the clutch 21 is in its designated coupling position. The first clutch 21 comprises a first coupling half 31, which is permanently connected to the first roller 5 and thus with the first motor 11 rotatably fixed, and a second coupling half 32, which is permanently connected to the first roller 5 coaxial gear rotatably.

The second clutch 22 is a shift clutch associated with an actuator, not shown in the drawing, which opens the second clutch 22 so that it does not transmit torque, and closes so that it transmits a torque. The second clutch 22 is disposed between two gears of the transmission 23 to transmit in the closed switching position of the second clutch 22, the torque generated by the second motor 12 of the one of the two coaxial with the second clutch 22 gears to the other.

The FIGS. 3a and 3b show in simplified form the structural design of the first clutch 21. One of the two coupling halves 31, 32, here the first coupling half 31, has a driver 33 which in the closed position (see. FIG. 3b ) of the first clutch 21 on a stop surface of the other coupling half, here the second Coupling half 32, applied. The driver 33 is arranged eccentrically with respect to the geometric axis of rotation of the coupling halves 31, 32. The driver 33 may, for. Example, be a relative to said rotation axis parallel pin which is stuck in the first coupling half 31, or be a functionally identical projection with such a pin. The driver 33 projects into an arcuate groove 34, which is introduced into the second coupling half 32. The aforementioned abutment surface is formed by an inside end surface of the groove 34. With the driver 33 - groove 34 - combination diametrically another such combination can be arranged. There may also be three or more circumferentially equally distributed driver 33 on the first coupling half 31 and with these drivers corresponding grooves 34 may be disposed on the second coupling half 33.

• Im Druckbetrieb treibt der zweite Motor 12 über das Getriebe 23 die zweiten Walzen 6 rotativ an. Hierbei ist die zweite Kupplung 22 geschlossen. Während dieses Druckbetriebes treibt der erste Motor 11 die erste Walze 5 rotativ an. Dabei wird ein vom ersten Motor 11 erzeugtes Drehmoment über die erste Walze 5 auf die erste Kupplungshälfte 31 übertragen, welche drehfest mit der ersten Walze 5 verbunden ist. Die Steuerungseinrichtung 37 steuert im Druckbetrieb den ersten Motor 11 in Abhängigkeit von der Drehzahl der zweiten Walzen 6 bzw. in Abhängigkeit von der Drehzahl des die zweiten Walzen 6 antreibenden zweiten Motors 12 derart an, dass der Mitnehmer 33 nicht in Kontakt mit der sich am Ende der Nut 34 befindenden Anschlagfläche gelangt. Der erste Motor 11 rotiert im Druckbetrieb also die erste Kupplungshälfte 31 derart, dass zwischen dem Mitnehmer 33 der ersten Kupplungshälfte 31 und der Anschlagfläche der zweiten Kupplungshälfte 32, die vom zweiten Motor 12 rotiert wird, ein Totgang 35 gesichert ist. Während des Druckbetriebes erfolgt keine rotative Mitnahme der zweiten Kupplungshälfte 32 durch die erste Kupplungshälfte 31. Beide Kupplungshälften 31, 32 rotieren aber synchron miteinander, wobei sich der Mitnehmer 33 in etwa in der Mitte der Nut 34 befindet, wie dies in Figur 3a dargestellt ist.

The system shown works as follows:

• In the printing operation, the second motor 12 rotatably drives the second rollers 6 via the gear 23. Here, the second clutch 22 is closed. During this printing operation, the first motor 11 rotatively drives the first roller 5. In this case, a torque generated by the first motor 11 is transmitted via the first roller 5 to the first coupling half 31, which is rotatably connected to the first roller 5. In the printing operation, the control device 37 controls the first motor 11 as a function of the rotational speed of the second rollers 6 or in dependence on the rotational speed of the second motor 12 driving the second rollers 6 in such a way that the driver 33 is not in contact with itself at the end the groove 34 located stop surface passes. The first motor 11 rotates in the printing operation, ie the first coupling half 31 such that between the driver 33 of the first coupling half 31 and the stop surface of the second coupling half 32, which is rotated by the second motor 12, a backlash 35 is secured. During the printing operation, no rotative entrainment of the second coupling half 32 by the first coupling half 31. However, both coupling halves 31, 32 rotate synchronously with each other, wherein the driver 33 is located approximately in the middle of the groove 34, as in FIG. 3a is shown.

In FIG. 4 a diagram is shown whose coordinate indicates the current I and whose abscissa indicates the time t. The curve entered in the diagram shows the Motor current of the first motor 11 over time t. Recognizable are periodically repeating increases in current 36, which occur in the rhythm of the vibration of the vibrating roller 7. Each of the current increases 36 occurs shortly before one of the repetitive with the same periodicity contacts the lifter roller 7 with the first roller 5. The first motor 11 is so shortly before the faster rotating first roller 5, the slower rotating lifter roller 7 during the contact of the two Rollers 5, 7 rotatably accelerated together with an increased flow, so that for this acceleration of the squeegee roller 7 sufficient torque is available and thus no excessive slip within the inking unit 3 between the first roller 5 and the second roller 6 during the acceleration phase. Thus, the acceleration of the lifting roller 7 is ensured by the first roller 5, without a speed drop of the first roller 5 and a resulting slip of the first roller 5 to the rest of the inking unit 3, guaranteed. The momentum of the lifting roller 7, the so-called lifter stroke, can be at least partially compensated by a torque precontrol without the control having to react to a speed deviation. The torque precontrol takes place on the basis of a characteristic field that describes the torque to be controlled as a function of the machine rotation angle and the engine speed. It is recommended to provide an acceleration control loop in addition to the described speed control loop. This can measure, for example by a Ferraris sensor, the current acceleration of the first roller 5 and react very quickly to the disturbance torque of the lifting roller 7, before the speed of the first roller 5 breaks down.

In the cleaning mode of the inking unit, which is a maintenance mode, the detergent and the rinse water are successively introduced by means of the sprayer 8 in the inking unit 3 and the soiled detergent is removed by means of the squeegee device 9 from the inking unit 3. In this maintenance mode, the second clutch 22 is opened, so that the second rollers 6 are no longer rotatably driven by the second motor 12. In the maintenance mode, the second rollers 6 are driven together with the first roller 5 by the first motor 11, the first clutch 21 being closed. The first clutch 21, which is a so-called self-switching clutch, is closed by the fact that as a result of the first Motor 11 transmitted to the first coupling half 31 torque of the driver 33 is in contact with the formed at the end of the groove 34 stop surface and is held, the backlash 35 has the value zero, as in FIG. 3b is shown. In the self-switching clutch shown in the embodiment, the switching condition is therefore the angle of rotation which occupies one half of the coupling relative to the other half coupling.

According to a modification not shown in the drawing, the first clutch 21 is not as a self-switching clutch, but as a z. B. formed by an actuator switchable clutch.

The rollers 5, 6, in the manner described in connection with the maintenance mode, wherein these rollers 5, 6 are driven only by the first motor 11, in other operating modes different from the printing mode, for. B. during a so-called Farbeinlaufes be driven.

LIST OF REFERENCE NUMBERS

1

press

2

Plate cylinder

3

inking

4

Ink fountain roller

5

first roller

6

second roller

7

vibrator roller

8th

spraying

9

doctor device

10

. \.

11

first engine

12

second engine

13-20

. \.

21

first clutch

22

second clutch

23

transmission

24-30

. \.

31

first coupling half

32

second coupling half

33

takeaway

34

groove

35

backlash

36

current increase

37

control device

I

amperage

t

Time

Claims (7)

1. Method of operating a printing press (1) in a printing mode and in another mode of operation, wherein in the printing mode, a vibrator roller (7) is periodically brought into contact with a first roller (5) of an inking unit (3), wherein the first roller (5) is driven to rotate by a first motor (11), and wherein a second roller (6) of the inking unit (3) is driven to rotate by a second motor (12),
   characterized by
   the fact that
   no torque is transmitted from the first motor (11) to the second roller (6) by a clutch (21) arranged between the first motor (11) and the second roller (6),
   the first motor (11) is actuated by a control device (37) to rotate the first roller (5) at a rotational speed that is at a constant ratio to the rotational speed of the second roller (6), and
   in the other mode of operation, the first roller (5) and the second roller (6) are driven by the first motor (11) to rotate and a torque is transmitted form the first motor (11) to the second roller (6) via the clutch (21).
2. Method according to Claim 1,
   characterized by
   the fact that the other mode of operation is a service mode.
3. Method according to Claim 2,
   characterized by
   the fact that in the service mode, the inking unit (3) is washed.
4. Method according to one of claims 1 to 3,
   characterized by
   the fact that in the printing mode, the motor current of the first motor (11) is periodically increased by the control device (37).
5. Method according to Claim 4,
   characterized by
   the fact that the motor current increases occur each time shortly before the vibrator roller (7) meets the first roller (5) to keep the circumferential speed of the first roller (5) constant due to the motor current increases despite the impact.
6. Method according to one of claims 1 to 5,
   characterized by
   the fact that in the printing mode, the clutch (21) is rotated maintaining a lost motion (35) of the clutch (21).
7. Method according to Claim 6,
   characterized by
   the fact that in the printing mode, the lost motion (35) is maintained between a first clutch half (31) and a second clutch half (32) of the clutch (21) in the circumferential direction.

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