EP2919993B1 - Monitoring system for the alignment of an inline printing press - Google Patents

Description

The present invention relates to a monitoring system for the alignment of printing units of a series printing machine, a suitably equipped series printing machine and a monitoring method for the alignment of printing units of a series printing machine.

It is generally known that printing units are arranged in a row in the form of a series printing press. In this case, the supply to the individual printing units takes place sequentially, so that between the individual printing units, which are responsible for each different colors, a corresponding free conveying length of the pressure medium is present. The printing medium is often provided by a paper roll and rolled out there and is web-shaped. To make sure that individual colors of the individual printing units are applied register-accurate to each other on the printing medium, it is known that so-called print markers are used. The print markers are part of the print image or are printed on the print medium at the side or at the edge of the print image. This can be determined by appropriate sensors, in particular by sensor devices with sensor units for each printing unit, the exact position of the printed image on the print medium. On the basis of this recognition, the associated printing unit settings are aligned, that is to say in particular a mechanical displacement of the individual pressure rollers in their axial direction.

A disadvantage of known series printing machines and corresponding monitoring systems with sensor devices is that they are limited in terms of their recognition width in order to provide the necessary high speed in terms of recognition at high printing speeds available. However, if a change of media or, for the same print medium, the feed change takes place with a new roll, different properties of the print medium may occur due to batch differences. These are in particular changes in the mechanical stability, preferably based on the tensile strength or the modulus of elasticity of the pressure medium. This variation can lead to so-called sheet travel. This means that the two lateral edges of the print medium can withstand different levels of tension applied by the press. This shifts a corresponding pressure medium laterally, that is transversely to the conveying direction, along the respective printing units. This shift error or this offset increases over the course of the entire series printing machine, ie from printing unit to printing unit. These are very large differences in the range of several millimeters compared to small offset situations in the course of a batch in a feed roll. Due to the relatively small detection areas of the sensor unit, it may now happen that due to the large offset during reel change, no recognition of the print markers can take place. In such a case, the machine stops and an operator of this series printing machine must manually adjust the corresponding offset data and, accordingly, manually align the printing units. By stopping the machine, however, at least the length of the pressure medium present in the machine at that time is produced as rejects or so-called waste. Also if the machine is not stopped, the printed images of the individual printing units to each other in an inadmissible manner. Although it is possible to continue printing, at least one section of the printing medium is subsequently disposed of as scrap. In other words, reel change in known in-line press monitoring systems often involves high rejects by stopping the machine and manually reorienting. Also, this creates a loss of time, which is required by stopping, replacing and restarting the series printing machine.

The DE 10 2006 030 170 A1 further describes a generic system and a generic method.

It is an object of the present invention to at least partially overcome the disadvantages described above. In particular, it is an object of the present invention to provide a monitoring system for the alignment of printing units of a series printing machine, a suitably equipped series printing machine and a monitoring method for the alignment of printing units of a series printing machine, which reduce waste in a cost effective and simple manner, and in particular a smooth roll change allow in the supply of the pressure medium.

The above object is achieved by a monitoring system having the features of claim 1, a series printing machine having the features of claim 7 and a monitoring method having the features of claim 8. Further features and details of the invention will become apparent from the dependent claims, the description and the drawings.

An inventive monitoring system is used to align printing units of a series printing machine, in particular a gravure printing machine. Such a monitoring system has a sensor device with at least one sensor unit for each printing unit. These are designed to detect the position of a print mark on the print medium. For the subsequent alignment of the printing unit is this Information about the position of the print marker or the print mark used. A monitoring system according to the invention is characterized in that at least one sensor unit arranged downstream of the pressure curve of a first sensor unit is movable transversely to the conveying direction of the pressure medium. The results of the monitoring by the sensor device are used for the axial alignment of the respective printing unit. In other words, a controlled system is provided which adapts the respective printing unit to the detected offset of the printing medium. The adaptation, ie the coupling between the alignment of the respective printing unit and the sensor device, is preferably carried out in an electronic, in particular in a digital manner.

In contrast to known monitoring systems, an adjustability with regard to the monitoring range of each sensor unit can take place here. This relates in particular to so-called downstream sensor units, that is not the first sensor unit. This mobility is in particular a translational mobility. A mobility transverse to the conveying direction is to be understood in particular to mean a movement substantially perpendicular to the conveying direction.

With an inventive monitoring system, an automatic or at least semi-automatic adjustment of the downstream sensor units can now be set to a high offset. If a first offset is detected by the first sensor unit at the first printing unit, which is in particular outside a standard offset in continuous operation, this offset can be used for a repositioning of the downstream movable sensor units. In the case of a roll change, ie if a significantly increased offset is to be expected, such a monitoring system can be put into a special programming so that a movement takes place transversely to the conveying direction of the downstream sensor units based on the detected offset of the first sensor unit. This can reduce the probability that the downstream sensor units no longer recognize the print markers of the preceding printing units. Rather, a pre-displacement of the downstream sensor units in the direction of the offset, so that it is at the time at which the offset print mark is located in the downstream printing unit, the sensor unit has arrived in a suitable monitoring position. Accordingly, the probability is too to provide the orientation of the printing units by the information of the individual sensor units in the roll change significantly increased compared to static sensor units in known monitoring systems. Due to the fact that in this way alignment of the printing units can be done quickly and easily even in reel change situations, the reel change can be carried out in particular at a consistently high printing speed and especially without stopping and the production of rejects with respect to the printing medium.

As a printing medium in the context of the present invention are in particular on a roll storable print media in question. It may be z. B. to paper or plastic, in particular PE or PET act. Of course, the printing medium can be formed in one or more layers or one or more layers.

The sensor unit can be designed for the detection of the print mark in a variety of ways. In particular, however, it has a possibility of generating a light spot and associated evaluation optics in order to be able to perform a corresponding position determination of the print mark on the print medium at a sufficiently high speed. Of course, the sensor unit in addition to the actual sensor electronics and associated control electronics and wiring, z. B. for the power supply or the signal forwarding on. Of course, the signal forwarding can also be done wirelessly in order to make the mobility of the sensor unit even more easily available.

It may be advantageous if, in a monitoring system according to the invention, the at least one movable sensor unit is translationally movable by means of an actuator, in particular with an electric motor. As an alternative to an electric motor z. As well as the use of a pneumatic motor in the context of the present invention conceivable. An actuator serves the automatic or semi-automatic mobility of the sensor unit. For example, in the form of a spindle gear, a gear ratio can be made available in order to be able to ensure positionally accurate adjustability of the sensor unit via the actuator system. An electric motor can represent a particularly cost-effective and simple embodiment of such an actuator. Of course, other transmission variants for the transmission of force to the sensor unit to the translatory movement possible. As a cable guide to the movable sensor unit movable cable sheaths may be provided. In order to be able to provide a corresponding activation of the movement, the sensor device and / or each sensor unit can have a corresponding control unit in order to carry out a monitoring method completely or partially, as will be explained in more detail later.

Another advantage is when, in a monitoring system according to the invention, the at least one movable sensor unit is movable along a guide, in particular along a guide rail. The guide serves to predefine the path of movement of the sensor unit. In particular, it is a translational guide or guide rail. A guide rail is used for. B. the sliding bearing movement of the sensor unit along this guide rail. The mechanical design of such a guide can of course be adjustable, so that preferably also different large paths of movement for each sensor unit can be realized. The movement of the sensor unit along such a guide can also be designed as a traversing movement. In order to generate a movement of the sensor unit along the guide, in addition to the already described actuator, z. B. in the form of an electric motor, and other actuators, in particular a lever kinematics, are used.

In the context of the present invention, it can also be advantageous if, in the monitoring system according to the invention, the at least one movable sensor unit is designed to be movable as a function of an offset which has been detected by the sensor unit which precedes the pressure profile. This allows pre-positioning of the movable sensor unit. This advance movement is based on a signal communication between at least two mutually separate sensor units, so that the detected offset of a preceding sensor unit can be transmitted to the downstream movable sensor unit. This can be done in a simple way or controlled in a closed loop control. For the execution of this signal communication or the corresponding control of the movement of the sensor unit, the sensor unit and / or the sensor device may have a corresponding control unit. So there is a preparation for the expected minimum offset, so that, as already explained, an increase in the probability of detection of the offset print mark is achieved.

It may also be advantageous if, in a monitoring system according to the invention, the at least one movable sensor unit has a possible movement path, which is formed transversely to the conveying direction in the range of approximately ± 2% relative to the width of the pressure medium. Thus, a possibility of a movement path is indicated, which can compensate for a sufficient mobility with respect to the expected offset. As printing widths of the pressure medium z. B. values in the range between about 1000 and about 1500 mm in question. In particular, about ± 10 mm to about ± 20 mm are advantageous as possible movement paths. At the beginning of a new roll, it may be advantageous if the individual movable sensor units are arranged centrally relative to the corresponding movement path.

It is likewise advantageous if, in a monitoring system according to the invention, a control unit is provided for the execution of a monitoring method according to the invention which will be explained later. Accordingly, a monitoring system according to the invention brings the same advantages as will be explained later with reference to a monitoring method according to the invention.

Likewise provided by the present invention is an in-line printing machine having at least two printing units arranged in series for printing on a printing medium. An in-line printing machine according to the invention is characterized in that at least one monitoring device according to the present invention is provided for the alignment of the printing units. Accordingly, a series printing machine according to the invention brings the same advantages as have been explained in detail with reference to a monitoring system according to the invention.

• Erkennen eines Versatzes einer Druckmarke auf dem Druckmedium bei einem ersten Druckwerk,
• Bewegen einer Sensoreinheit einer Sensorvorrichtung eines zweiten Druckwerks quer zur Förderrichtung des Druckmediums in Richtung des erkannten Versatzes,
• Erkennen eines Restversatzes der Druckmarke auf dem Druckmedium bei dem zweiten Druckwerk.

The subject of the present invention is furthermore a monitoring method for the alignment of printing units of a series printing machine, in particular according to the present invention, comprising the following steps:

• Detecting an offset of a print mark on the print medium in a first printing unit,
• Moving a sensor unit of a sensor device of a second printing unit transversely to the conveying direction of the printing medium in the direction of the detected offset,
• Recognizing a residual offset of the print mark on the print medium at the second printing unit.

An inventive monitoring method is thus used in particular in a row printing press according to the invention, so that the same advantages can be achieved, as they have been explained in detail with respect to an in-line printing machine according to the invention as well as with reference to an inventive monitoring system.

In the sense of a monitoring method according to the invention, a pre-positioning of the following sensor unit of the second printing unit can take place. If an offset is detected in the first printing unit, the second sensor unit of the second printing unit can already be displaced in the direction of the detected offset in preparation for this offset. This monitoring method is in particular a special method which is used in a roll change of the printing medium. At high default probabilities, z. As when creating a sheet run, the print medium can be ensured in this way that even with a relatively large offset on the first printing unit, the other printing units are prepared for this large offset and can recognize the print mark also. This pre-positioning increases the security of the monitoring and thus reduces the likelihood of a machine stop. Thus, as has already been explained, the stop of the machine and the corresponding scrap or the so-called waste can be significantly reduced.

An advantage is further achievable if, in a monitoring method according to the invention, after the detection of the offset of a print mark on the print medium in a first printing unit, all the pressure units downstream of the sensor units are moved transversely to the conveying direction of the print medium in the direction of the detected offset. In a series printing machine with a large number of printing units, accordingly, sensor units of the third, fourth and following printing units can also be used as of first detection of an offset on the first printing unit to be moved accordingly. This also large offsets with correspondingly smaller actuators or a weaker power actuators with respect to the high printing speed can be moved sufficiently quickly by the Vorabpositionierung. This can be done to reduce the cost and the necessary space of the individual sensor units and the associated actuators. It can also be ensured that the row printing machine can be operated at full printing speed even in the case of reel change situations.

A monitoring method according to the invention can be further developed such that the movement of the sensor unit of the second printing unit takes place at least by the amount of the detected offset of the print mark on the first printing unit. In addition to the direction of the advance movement of the movable sensor unit, the minimum path of the movement along the path of movement is predefined in this way. The movement thus takes place at least by the detected offset. It can namely be assumed that the offset increases over the course of the printing press, ie from printing unit to printing unit in the same direction. The Vorabpositionierung by at least the amount of the detected offset for the following printing unit thus allows the minimum positioning of the at least expected further offset in this second printing unit. Of course, a larger travel than the amount of the detected offset can be used. This increase in movement can z. B. on further information, eg. B. on stored averages via statistical evaluation. Also, the increased Verfahrwegseinstellung based on a corresponding function of the detected offset is conceivable.

A further advantage can be achieved if, in a monitoring method according to the invention, a sensor unit of a third printing unit is moved transversely to the conveying direction of the printing medium by an amount which is composed of the detected offset and the detected residual offset. At the latest after passing the print mark through the second printing unit, both the offset and the detected residual offset are known. Accordingly, an expected residual offset for the own printing unit can be determined for the further displacement movements of the movable sensor units via the residual offset. Thus, over the Amount of the detected offset beyond a method of the movable sensor units of the following printing units done. In this way, an even more accurate pre-positioning of the following sensor units can be carried out. In particular, in series printing machines with a large number of printing units, so in multi-color printing with eight to twelve printing units, such a procedure is occupied with great advantages. Of course, mean values can also be formed by arithmetic evaluation in order to achieve a pre-positioning with higher accuracy.

It may also be advantageous if, in a monitoring method according to the invention, the movement of the sensor unit of the second printing unit in the direction of the detected offset also takes place when no print mark is detected at the second printing unit. In the case of very large offset situations and correspondingly high printing speed of the series printing press, it can happen that despite the pre-positioning on the second printing unit by the sensor unit, the print mark is not recognized. However, this does not necessarily mean a complete stop of the press. Rather, the further movement of the sensor unit on the second printing unit by the information about the direction of the detected offset compensate for this deficiency again and recognize after a short movement phase and the print mark on the second printing unit again. Thus, a complete stop of the in-line printing machine and the corresponding rejects can be avoided by a monitoring method according to the invention even if the possibility of detecting the print mark is lost.

An inventive monitoring method can be further developed such that it is executed as a special program for the duration of a roll change of the print medium. As a normal program, accordingly, other parameters for the positioning or movement of the individual sensor units can be used. In particular, the measurement engine, so the alignment of a light spot and the evaluation by the corresponding optics may differ in the special program according to the present invention from the normal program. The duration of the roll change is at least the time that is necessary to have completely within the series printing machine printing medium of the newly used role.

It is also advantageous if, in a monitoring method according to the invention after the end of the roll change, in particular after a predetermined print length, the special program is terminated. A predetermined print length can z. B. be one to two machine lengths of the pressure medium. After completion of the special program can be further controlled or further regulated in the already discussed normal program. In particular, when the normal program returns to the normal position, the sensor devices or the sensor units remain at the positions at which they were or were positioned at the end of the special program of the monitoring method.

Another advantage is achieved if, in a monitoring method according to the invention when moving the sensor unit of the second printing unit, the time offset to the first printing unit, in particular as a relation between the printing run length between the two printing units and the printing speed, is taken into account. In other words, the respectively downstream sensor unit still remains at its previous position until, for example, when the roll has changed, the new material has also reached this sensor unit. The previous material will usually not yet have the sheet travel. Thus, premature movement of the respective sensor unit would possibly result in the loss of the ability to detect these print marks. In particular, the quotient of the printing length between the two printing units and the printing speed is formed as a relation for the time offset. In this case, in particular, the necessary time for the movement of the sensor unit can be taken into account. In other words, the downstream sensor units are moved with time offset, in particular temporally accurate to the detected offset and thus pre-positioned not only locally, but also temporally.

Fig. 1

eine erste Ausführungsform einer erfindungsgemäßen Reihendruckmaschine,

Fig. 2a

eine erste Situation eines erfindungsgemäßen Überwachungsverfahrens,

Fig. 2b

eine zweite Situation eines erfindungsgemäßen Überwachungsverfahrens nach der Situation gemäß Fig. 2a,

Fig. 2c

eine weitere Situation eines erfindungsgemäßen Überwachungsverfahrens nach der Situation gemäß Fig. 2b und

Fig. 3

eine Ausführungsform von Druckmarken auf einem Druckmedium in Korrelation zu einer Sensoreinheit.

The present invention will be explained in more detail with reference to the accompanying drawing figures. The terms "left", "right", "top" and "bottom" used herein refer to an alignment of the drawing figures with normally readable reference numerals. They show schematically:

Fig. 1

A first embodiment of a series printing machine according to the invention,

Fig. 2a

a first situation of a monitoring method according to the invention,

Fig. 2b

a second situation of a monitoring method according to the invention according to the situation Fig. 2a .

Fig. 2c

a further situation of a monitoring method according to the invention according to the situation Fig. 2b and

Fig. 3

an embodiment of print marks on a print medium in correlation to a sensor unit.

In Fig. 1 schematically a series printing machine 100 is shown. Here are three printing units 110a, 110b and 110c shown. Via a plurality of guide rollers and pressure rollers, the guide and the promotion of the pressure medium 200 along the conveying direction F.

Again Fig. 1 can be seen, this embodiment of the row printing machine 100 is configured with a monitoring system 10 according to the invention. This has a control unit 40, which is connected in a signal-communicating manner with in each case one sensor unit 22a, 22b and 22c of a sensor device 20.

The sensor units 22a, 22b and 22c are each associated with a printing unit 100a, 100b and 100c. The individual sensor units 22a, 22b and 22c are of essentially identical design and have a guide 24 for translatory movement transversely to the conveying direction F. In order to be able to generate the above-described movement of the individual sensor units 22a, 22b and 22c, an actuator 30 in the form of an electric motor is provided in each case.

The Fig. 2a to 2c show a possibility of carrying out a monitoring method according to the invention. They are described schematically in particular with reference to the embodiment of a row printing machine 100 according to FIG Fig. 1 based. So is all three Fig. 2a to 2c a situation with three sensor units 22a, 22b and 22c, which correlate with associated printing units 100a, 100b and 100c (not shown). It can also be seen that a print mark 210 is applied to a print medium 200, not shown.

The process begins at the time of roll change of the print medium 200. Due to the roll change and corresponding change by batch differences of the modulus of elasticity of the print medium 200, an offset V is detected at the first printing unit 110a of the sensor unit 22a. At the time of detection of this offset V, the two further sensor units 22b and 22c immediately and automatically move in the direction of this offset V and, in one embodiment of this monitoring method, even exactly by the amount of the offset V. The result shows Fig. 2b , so that the downstream sensor units 22b and 22c have already been pre-positioned by the offset V. As soon as the printing mark 210 offset by the offset V has now also reached the second printing unit 110b, the pre-positioning of the sensor unit 22b can now also be used to directly detect the residual offset R of the printed mark 210. On the basis of this residual offset R, a movement of the third sensor unit 22c is again effected by this residual offset R. This can be carried out in an identical manner for further printing units, so that the pre-positioning can almost exclude the loss of the ability to recognize the printed mark 210.

Fig. 3 shows one way in which different print marks 210 can be arranged on the print medium 200. These have in the direction of the conveying direction F at the beginning, ie at its upper end, a straight edge and at its lower end an oblique edge. In this way, in addition to a positioning and alignment of the individual printing units 110a, 110b and 110c in the conveying direction F, an orientation transversely to the conveying direction F can take place. By way of the relation between a light point of the sensor unit 22a and the oblique edge of the print mark 210, this lateral offset V, which is the axial offset with respect to the respective printing unit, can be detected. This determination result is used as an input for the controlled alignment of the respective printing unit 110a, 110b and 110c. For each individual printing unit 110a, 110b and 110c, a separate printing mark 210 can be applied to the printing medium. Also good to see in Fig. 3 is the freedom of movement along a path of movement S for this sensor unit 22a. Here, a guide 24 is provided in frame construction, so that an even more accurate pre-positioning along the movement path S is possible.

The above explanation of the embodiments describes the present invention solely by way of example.

LIST OF REFERENCE NUMBERS

10

monitoring system

20

sensor device

22a

sensor unit

22b

sensor unit

22c

sensor unit

24

guide

30

actuators

40

control unit

100

Series printing machine

110a

printing unit

110b

printing unit

110c

printing unit

200

print media

210

print mark

F

conveying direction

R

residual offset

S

motion path

V

offset

Claims (14)

1. Monitoring system (10) for the alignment of printing units (110a, 110b, 100c) of an in-line printing press (100), having a sensor device (20) with at least one sensor unit (22a, 22b, 22c) for each printing unit (110a, 110b, 100c), in order to detect the position of a printed mark (210) on a printing medium (200),
   at least one sensor unit (22b, 22c) arranged downstream of a first sensor unit (22a) in the printing run being movable transversely with respect to the transport direction (F) of the printing medium (200),
   characterized in that
   the at least one movable sensor unit (22a, 22c) is designed to be movable on the basis of an offset (V) which has been detected by the preceding sensor unit (22a) in the printing run.
2. Monitoring system (10) according to Claim 1,
   characterized in that
   the at least one movable sensor unit (22b, 22c) can be moved translationally by means of an actuator mechanism (30), in particular comprising an electric motor.
3. Monitoring system (10) according to one of the preceding claims,
   characterized in that
   the at least one movable sensor unit (22a, 22b) is movable along a guide (24), in particular along a guide rail.
4. Monitoring system (10) according to one of the preceding claims,
   characterized in that
   the at least one movable sensor unit (22a, 22b) has a possible movement travel (S) which is designed to lie in the range of about +/- 2%, based on the width of the printing medium (200), transversely with respect to the transport direction (F).
5. Monitoring system (10) according to one of the preceding claims,
   characterized in that
   a control unit (40) is designed for the implementation of a monitoring method, in particular having the features of one of Claims 7 to 13.
6. In-line printing press (100) having at least two printing units (110a, 110b, 110c) arranged in line for the printing of a printing medium (200),
   characterized in that
   at least one monitoring device (10) having the features of one of Claims 1 to 5 is provided for the alignment of the printing units (110a, 110b, 110c).
7. Monitoring method for the alignment of printing units (110a, 110b, 110c) of an in-line printing press (100), in particular having the features of Claim 6, having the following steps:

   - detecting an offset (V) of a printed mark (210) on the printing medium (200) at a first printing unit (110a),

   characterized in that the following steps are carried out:

   - moving a sensor unit (22b) of a sensor device (20) of a second printing unit (110b) transversely with respect to the transport direction (F) of the printing medium (200) in the direction of the detected offset (V),

   - detecting a residual offset (R) of the printed mark (210) on the printing medium (200) at a second printing unit (110b).
8. Monitoring method according to Claim 7,
   characterized in that
   following the detection of an offset (V) of a printed mark (210) on the printing medium (200) at a first printing unit (110a), all the sensor units (22b, 22c) arranged downstream in the printing run are moved transversely with respect to the transport direction (F) of the printing medium (200), in the direction of the detected offset (V).
9. Monitoring method according to either of Claims 7 and 8,
   characterized in that
   the sensor unit (22b) of the second printing unit (110b) is moved at least by the magnitude of the detected offset (V) of the printed mark (210) at the first printing unit (110a).
10. Monitoring method according to one of Claims 7 to 9,
    characterized in that
    a sensor unit (22c) of a third printing unit (110c) is moved transversely with respect to the transport direction (F) of the printing medium (200) by an amount which is composed of the detected offset (V) and the detected residual offset (R).
11. Monitoring method according to one of Claims 7 to 10,
    characterized in that
    the sensor unit (22b) of the second printing unit (110b) in the direction of the detected offset (V) is also moved when no printed mark (210) is detected at the second printing unit (110b).
12. Monitoring method according to one of Claims 7 to 11,
    characterized in that
    it is implemented as a special program for the duration of a roll change of the printing medium (200).
13. Monitoring method according to Claim 12,
    characterized in that
    after the roll change has been completed, in particular after a predefined printing length, the special program is terminated.
14. Monitoring method according to one of Claims 7 to 13,
    characterized in that
    during the movement of the sensor unit (22a) of the second printing unit (110b), the time offset to the first printing unit (110a) is taken into account, in particular as a relation between the printing running length between the two printing units (110a, 110b) and the printing speed.

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