Abstract:
There is described a regulating system for register adjustment in a printing press which has at least one printing unit, wherein the regulating system has at least one register regulator. In the regulating system, a pilot control variable and/or a register error estimated variable are/is provided for influencing the register adjustment. A drive bus is advantageously used for transferring these variables between different printing units, wherein the register regulation is advantageously distributed in a decentralized manner among different regulating devices for carrying out the drive regulation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National Stage of International Application No. PCT/EP2006/068450, filed Nov. 14, 2006 and claims the benefit thereof. The International Application claims the benefits of German application No. 10 2005 054 975.6 DE filed Nov. 16, 2005, both of the applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The invention relates to register regulation of a printing press and to a corresponding method. A printing press is e.g. a web-fed rotary press, a flexographic printing press or similar. Printing presses of said kind comprise one or more printing units. 
       BACKGROUND OF INVENTION 
       [0003]    In the case of a web-fed rotary press, the register-true coordination of a printing cylinder which prints on one side of a web takes place by means of register regulators. A register deviation which is picked up by a sensor, this being assigned to one web side, is supplied to one input of the register regulator. The register regulator is connected to a bus of a supervisory controller via a further input. The supervisory controller comprises a control station, section computers and service interfaces. The desired values for drive regulation of motors are specified by means of the supervisory controller. The unexamined German patent application DE 197 23 059 A1 indicates in particular that it is important that a color register does not deviate from a tolerance range. The speed of the color register regulation is particularly significant. The faster the register regulation, the more advantageous this is. In order to minimize error delays, it is proposed that a sensor be arranged immediately behind each printing position. 
         [0004]    For the purpose of the register regulation, register marks are additionally printed on the web by printing cylinders, for example, and are picked up by means of a pair of sensors that are arranged behind the last print unit. The register marks that are printed on the web are picked up by the sensor and analyzed in a measuring head of the sensor. The ascertained register deviations of the printing cylinders are routed from an output of the sensor to a supervisory controller/regulator. 
       SUMMARY OF INVENTION 
       [0005]    An object of the present invention is to achieve cost-effective and/or improved faster processing of signals relating to register regulation. Furthermore, it is also an object of the invention to achieve improved error correction. 
         [0006]    This object is achieved by means of an apparatus as claimed in an independent claim and by means of a method as claimed in a further independent claim. The dependent claims relate to advantageous non-obvious embodiments of the invention. 
         [0007]    As a result of the web tension, the register adjustment of one printing unit has a direct and immediate influence on the register compliance of the subsequent printing units in the web run. Consequently, a register adjustment in one printing unit cannot take place independently of the register adjustments of the other printing units. The influence is known in relation to speed, spacing and material properties. 
         [0008]    According to the invention, when register adjustments are performed in one printing unit, the register compliance of subsequent printing units can be improved by utilizing the drive communication for the purpose of synchronized compensation movement. Register errors occur e.g. due to tension and strain fluctuations in the draw-in unit and unwinder as a result of splicing and irregular winding, and hence in the material which is transported in the machine. Tension and strain fluctuations occur in the machine due to non-driven rollers during acceleration and braking operations, for example, since these non-driven rollers must be accelerated and braked by the web. The consequential register errors are estimated e.g. with the aid of a model and supplied to the register regulator as pilot control. 
         [0009]    The prior art only discloses supervisory register regulators which have a centralized structure, which regulate each register individually, and which can only respond slowly to register errors using +/−adjustment instructions. 
         [0010]    In an embodiment of the invention, provision is made for implementing a register decoupling algorithm directly in the individual drives of a printing press or in the drives of the register rollers. 
         [0011]    The drive communication is advantageously utilized in order to encompass the overall register decoupling network, for example. 
         [0012]    The decoupling and relaying algorithms are executed e.g. in a decentralized manner in each individual drive which interacts with the paper web, and the synchronized drive communication which already exists for the synchronized individual drive mechanism is utilized for the purpose of synchronizing the register adjustments in the overall printing press or for influencing the decoupling. Similar algorithms can be utilized in printing presses having a longitudinal shaft and register rollers for register adjustment, in order to decouple the adjustment movement of one register roller from the register compliance of the subsequent printing positions. For this, e.g. the register rollers are equipped with drives that are synchronized with each other, and the decoupling network is realized with the aid of the these register roller drives and their drive communication. 
         [0013]    Provision is advantageously made for implementing a register error estimator in the individual drives of a printing press. Relevant material variables are determined with the aid of the individual drives. For this purpose, material tensions, material speed, rotational speeds and rotational moments are measured and analyzed by the drives themselves. The measured variables are utilized e.g. as input values for the model in order to supply the pilot controls to the register regulators. 
         [0014]    It is also advantageous to implement both aforementioned methods and the register regulator for an axis directly in the individual drives of a printing press: 
         [0015]    By virtue of the register decoupling and register error pilot control, it is possible to achieve a very fast register regulation per printing position. Furthermore, by virtue of this method for register error estimation, it is possible to omit a measurement after each printing unit and hence to reduce the number of measurement positions, e.g. by measuring the register error after every 2nd, 3rd, 4th, etc. or only after the last printing unit and supplying the measured value to the relevant register regulators. 
         [0016]    An advantage of the invention is the reduction in spoilage associated with register adjustments, said spoilage being necessary e.g. when setting up the machine (reduction in starting spoilage) or being present in the event of disruptions that are caused by a roll change or material change. The register decoupling advantageously effects a rapid, decentralized register regulation. 
         [0017]    In a further embodiment, a pilot control variable and/or a register error estimated variable is provided for influencing the register adjustment in the regulation system, wherein a drive bus is utilized for transferring these variables between different printing units, wherein the register regulation is advantageously distributed in a decentralized manner among various regulating devices for the purpose of carrying out the drive regulation. 
         [0018]    A printing press has e.g. at least one print unit, a drive unit which is assigned to the print unit, a regulating unit at least for regulating one drive unit, and a printing mark measuring device and/or a register measuring device. The printing mark measuring device or the register measuring device is directly connected via means for signal transfer to the regulating unit, which is provided at least for regulating one drive unit. The direct connection produces a shorter signal path and hence a reduction in the signal propagation time. It is thus possible to respond more quickly and effectively to discrepancies in the print format. 
         [0019]    The register measuring device has e.g. a CCD camera or a scanner device. The register compliance of a printer can be determined from the optical signals that are picked up by the register measuring device. In the case of color printers, this involves color registers—also called passes—or a corresponding color register measuring device. A color register measuring device can be applied both to printing marks and to prints without printing marks using the print itself. 
         [0020]    The printing press has a large number of printing units, for example, wherein these must rotate in a manner which is exactly synchronous and correctly oriented relative to each other in order to ensure a good print format. In order to control this, e.g. printing marks are applied to the paper that is to be printed. At least one printing mark measuring device—also called a feeler—is provided for analyzing these printing marks. With the aid of the printing mark measuring device, the difference between the individual printing units or colors is measured. Such a difference can also be determined by analyzing the print format using a (color) register measuring device and a corresponding analysis unit. In this context and in the following, alternatively or in combination, printing mark is also understood to signify a register mark. The printing mark measuring device is therefore understood to signify a register mark measuring device which is used as an alternative to or in combination with the printing mark measuring device. The register mark measuring device is provided for the purpose of recognizing the register marks. When using the improved printing mark measuring device or register mark measuring device, a high-resolution image analysis device is particularly advantageous in this case. The measurement of the difference serves to determine at least one correction value for e.g. a circumferential register of the printing unit(s) or color(s) that are situated outside of the tolerance. These correction values are time-critical and the precise management of these correction values is very important for the quality of the print format. The printing mark measuring device or the register measuring device is directly linked to a regulating unit for drive regulation of a drive of the printing press. A means for signal transfer such as e.g. a cable transfer or even a radio transfer can be utilized for the link. Such a direct injection results in faster processing of the correction value, which is calculated e.g. in the regulating unit, and consequently in better quality of the print format. 
         [0021]    By contrast, the unexamined German patent application DE 197 23 059 A1 provides for the signal of the sensor to be transferred to an assigned register regulator, wherein the register regulator is connected to a bus including a supervisory controller and a correction value for improving the register compliance can be supplied to a drive regulator via the control station, corrected as a desired value of the supervisory controller. 
         [0022]    This long chain of communication partners is now shortened according to the invention, in that the printing mark measuring device is directly connected to the regulating unit, which is provided at least for regulating one drive unit, by a means of signal transfer. 
         [0023]    In an advantageous embodiment of the invention, the printing mark measuring device analyzes the measurement signal of the printing mark measuring device or of the register measuring device in an analysis unit. The analysis unit of the printing mark measuring device has a direct data link, e.g. a serial link, to the regulating unit, i.e. a drive regulator of the printing unit. Software which analyzes the measured values of the printing mark measuring device and calculates the correction values or even directly implements the correction can run in the regulating unit. 
         [0024]    As a result of the direct coupling and hence faster processing of the correction values, a qualitative improvement of the print format is produced. Moreover, as a result of the omission of a previously necessary separate correction computer, a cost optimization is produced. The correction signal or correction signals are sent to the regulating unit at a control station e.g. also via an existing communication connection within a printing press. 
         [0025]    The printing mark measuring device, which has an analysis unit, the analysis unit converting the signals that are generated by a printing mark measuring device into e.g. digital signals, sends these digital signals e.g. via a bus system to the regulating unit. A bus system which is already in use in the printing press can advantageously be utilized as a means for signal transfer. A corresponding approach applies in the case of a register measuring device. 
         [0026]    In a further advantageous embodiment, the regulating unit has the integrated analysis unit which converts the signal that is generated by the printing mark measuring device or the register measuring device, e.g. an analog signal, into a digital signal that can be processed by the regulating unit. 
         [0027]    In a further advantageous embodiment, the regulating unit, which is provided at least for regulating one drive unit and is directly connected to the printing mark measuring device or the register measuring device, has a master functionality relative to further drive units or relative to further regulating units. In this case, a drive unit has at least one electric motor and one static converter. 
         [0028]    In one embodiment, the regulating unit for regulating a drive unit of a printing press has a signal interface for the input of a signal from a printing mark measuring device or the register measuring device. 
         [0029]    In a method for operating a printing press, the printing mark measuring device transmits a printing mark signal or the register measuring device transmits a register measurement signal to the regulating unit. The regulating unit calculates a correction value for the movement regulation of at least one drive unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Exemplary embodiments of the invention are illustrated in the drawing and are explained in greater detail below, wherein: 
           [0031]      FIG. 1  shows a decentralized register regulation, 
           [0032]      FIG. 2  shows measured variables in the case of register regulation, 
           [0033]      FIG. 3  shows further measured variables in the case of register regulation 
           [0034]      FIG. 4  shows a diagram relating to a method for decoupling the registers, and 
           [0035]      FIG. 5  shows a printing press. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0036]    For the purpose of explaining the figures, reference is made to the claims. 
         [0037]    The illustration according to  FIG. 1  shows a register decoupling with a register error estimation in the case of a printing press having four print units, wherein the four print units are assigned the register regulators  10 ,  11 ,  12  and  13  respectively. The register regulator  10  has a model  26 . Input variables that are entered into this print model comprise print parameters  37  and, in addition, the drive speed and a register error which was detected by means of a register error measurement system. These two input signals are indicated by means of arrows. An estimated register error is determined by means of the model  26 . This is shown by an arrow emerging from the model  26 . A value which represents a material elongation of the printing material is provided as a further input for the model  26 . As a further input variable, the register regulator  10  also uses a correction signal from a register monitoring system  9 . The incoming signals are processed according to the illustration in  FIG. 1 . An output signal of the register regulator  10  is the value for register compensation. This value for register compensation is transmitted to the register  21 . In addition to a first print unit, the printing press also has further print units to which corresponding register regulators are assigned. The first print unit has register regulator  10 , the second print unit has register regulator  11 , etc. Data is passed between the register regulators  10  to  13 . This relates to both the register error estimated variable  16  and a pilot control variable  15 . This pilot control variable  15  corresponds to the decoupling signal  40  and is therefore used for the decoupling. The register regulators  11  to  13  are constructed in a manner which corresponds to the register regulator  10 . However, the register regulators  11 ,  12  and  13  differ from the register regulator  10  in that the pilot control variable  15  is added to the value of the register compensation, this value being subsequently transmitted to the register  22 ,  23  or  24 . 
         [0038]    The illustration according to  FIG. 2  shows the improvement in the register regulation as a result of decoupling, with reference to the example of a machine startup. The effect of the decoupling increases with the number of printing units and web length. This means that the positive effect of the invention is more noticeable in the case of a large number of printing units and a long printing press. The illustration according to  FIG. 2  shows the speed with and without decoupling in the first diagram, wherein the register errors at various subsequent printing units are shown in each case in the subsequent diagrams. It is evident from the illustration that the error increases with the increasing number of printing units, wherein the error can be significantly reduced by means of the inventive decoupling and the register error estimator. This is shown particularly clearly in the case of the printing unit G 4 . In this case, the printing units G 2  and G 3  are located before the printing unit G 4  with regard to the direction of movement of a printing material. 
         [0039]    The illustration according to  FIG. 3  shows a manual adjustment of the register of a printing unit. In this case, the register errors for the various printing units (G 2 , G 3  and G 4 ) are shown again in the diagrams. Furthermore,  FIG. 3  shows that the register error also depends on the web speed of the printing material, wherein the units are shown in relation to the web speed of 100 m/min and 200 m/min. 
         [0040]    The illustration according to  FIG. 4  shows a register decoupling network in a schematic illustration which broadly corresponds to the illustration according to  FIG. 1  and again describes the underlying functionality of the invention. It can be seen from  FIG. 4  that, in the case of the present invention, it is particularly significant that register error estimated variables of a preceding regulator are passed to the various regulators, wherein a pilot control variable is also transferred in addition to this register error estimated variable. Of course, further pilot control variables, which must be adapted to the relevant printing press, can also be used in the various regulators. 
         [0041]    In the illustration according to  FIG. 5 , the structure of a printing press DM,  3  is shown in the form of a schematic representation. The printing press  3  has printing units  17 ,  18  and  19 . A regulating system  1  is established by means of register regulators  10 ,  11 ,  12 . The regulating system  1  also has a data bus  35 . Paper webs PB 1  to PB 3  run from paper rolls P 1  to P 3  through print units DE, DE 1  and DE 2  to a folding device F. The paper web PB 1 , after passing through the print units DE 1  and DE 2 , is carried to other processing units (which are not shown in the illustration according to  FIG. 1 , however). The paper web PB 1  therefore tails off with a broken line in the drawing. 
         [0042]    The print units DE, DE 1  and DE 2  are represented by means of an approximately H-form external contour. The print units DE, DE 1  and DE 2  comprise in each case ten cylinders ZY which are arranged into two groups G 1 , G 2  of five cylinders ZY each. All cylinders or wheel-form machine elements of a print unit DE, DE 1 , DE 2  and of a folding device F are designated as cylinders ZY here. The paper webs PB 1  to PB 3  run via these groups G 1 , G 2 , which are designated as printing positions in the print units DE. A printing position consists essentially of e.g. a blanket cylinder, a plate cylinder and an inking and damping unit. Each printing position allows a color to be printed on one side. All printing positions which work in conjunction with a folding device F, i.e. all printing positions in which the printed paper webs PB 1  to PB 3  are transported to a folding device F, belong to a rotation. In this case, the print units DE, DE 1 , DE 2  are usually housed in printing towers. 
         [0043]    Each individual driven cylinder has a drive device A 1  to A 29 . An electric machine  31  is assigned to the drive devices A 1  to A 29 , wherein only one electric machine  31  for driving one roller  33  is illustrated in the  FIG. 5  for reasons of space. A regulating unit RE 1  to RE 29  is assigned to the drive device A 1  to A 29 . Depending on the level of integration in the drive units, the drive unit has e.g. a motor and a static converter. In the case of a higher level of integration, the drive unit has an integrated regulating unit RE 1  to RE 29 . Drive units A 30  to A 34  and associated regulating units RE 30  to RE 34  are also provided for the folding device F. The print units DE, DE 1  and DE 2  and the folding device F have a regulating device RE 1 , RE 20 , RE 21  and RE 30  with master functionality for each drive group including the drive units. The regulating devices RE 1  to RE 10  of a drive group are networked together for data communication purposes. The regulating units RE 1 , RE 20 , RE 21  and RE 33  and the drive units A 1 , A 20 , A 21  and A 30  which have a control or master functionality are characterized by a thicker outline in the drawing. 
         [0044]    An associated master computer L 1  to L 4  is assigned to a group of drive units or regulating units and has a data connection to these. The master computers L 1  to L 4  are also connected together by means of a master computer communication LK 1  to LK 3 . This is represented in the drawing by means of a broken line. Further embodiments and data networks are also possible here. 
         [0045]    A master computer L 1  to L 4  is responsible for supervisory process organization. A printing mark measuring device ME 1 , ME 2  and ME 3  which is used for picking up printing marks on the paper webs PB 1 , PB 2  and PB 3  is arranged at the end of the print units DE and DE 2 . The printing mark measuring device ME 1 , ME 2  and ME 3  is connected to a regulating device RE 1  or RE 21 . The regulating device RE 1  or RE 21  determines the correction value for the drive or drives of the drive units in order to improve the print format. Consequently, the previously required procedure in which the correction value was calculated by means of a separate electronic analysis system and output to the relevant drive units of the printing units, e.g. via a pulse-width modulated binary signal, is superseded. A previously required long path for the transfer of the correction values to a master computer of the printing press, e.g. via a serial link, via Profibus® or Arcnet, is no longer necessary. 
         [0046]    As a result of connecting the printing mark measuring device ME 1 , ME 2 , ME 3  directly to the regulating unit RE 1 , RE 21  or the drive regulator of the printing unit, e.g. via a serial link (DS), the signal path is considerably shortened, this being advantageous in terms of the faster analysis of the signals or the correction. As a result of the direct injection and hence faster processing of these correction values, a quality improvement of the print format is produced. As a result of omitting a separate correction computer, cost optimization is also achieved. The correction signals can be transmitted from the regulating device to a master computer or a control station via existing communication connections. 
         [0047]    For the paper web PB 1 , as an alternative to or in combination with the printing mark measuring device ME 1 , provision is made for a register measuring device RME which has a data connection to the regulating unit RE 1 . A register measurement signal RMS, which is represented as an arrow in the  FIG. 1 , is then used to correct the printing.