EP0654350B1 - Method for automatic cleaning of cylinders in printing presses with a central control system - Google Patents

Abstract

A method for fully automatic cylinder cleaning in printing machines which are equipped with a central control system and automated washing devices, having an extension of the central control system, by means of which the operating parameters are recorded to determine the respectively optimum washing sequence programmes for each individual washing device by access to the central printing-machine control system, the respectively optimum washing sequence programmes for each individual washing device are determined automatically, and the individual washing devices are controlled by the respectively corresponding optimum washing sequence programme.

Description

The invention relates to a method for fully automatic cylinder cleaning in printing presses with a central control system.

Printing machines are used in particular for newspaper web presses, commercial web presses and sheetfed presses for all printing processes, such as offset printing, anilox offset, intaglio printing, flexographic printing, anilox flexo, letterpress printing and gravure printing. The cylinders to be cleaned are understood to mean all rollers, rollers and cylinders, in particular blanket cylinders, impression cylinders, plate and form cylinders, cooling rollers, guide rollers, inking rollers and dampening rollers.

The machines in question have in common that intensive contact between the printing material and the cylinder is necessary for guiding, processing and driving printing material sheets or printing material webs. This creates deposits of paper dust, printing ink and possibly powder dust on the cylinders. These deposits affect the functionality of the cylinders; For example, deposits on blanket cylinders have a negative impact on offset printing: the dot sharpness is lost and some print sections no longer print correctly. In the case of blanket cylinders in particular, however, the deposition rate is particularly high owing to the high viscosity and adhesiveness of the printing ink. For print quality and operational safety, it is therefore essential that the cylinders mentioned are regularly freed of contaminants.

To remove these deposits, the printing process is usually interrupted and the cylinders are washed by hand. Not only does this take a lot of time - the washing process, and thus the pressure interruption, takes around 15 minutes - the washing worker must also be very careful so that no fibers from the cleaning rag remain on the surface, especially the blanket cylinder; because they cause misprints. Such hand washing also endangers the health of the washing worker: contact with solvents dissolves the natural protective coating of the skin, inhaling high concentrations of solvent vapors at least affects the general well-being.

More recently, automated pressure cylinder washing devices have also been used, as can be seen, for example, from EP 0 419 289 A2:

The automated washing device described here essentially consists of a brush roller which can be moved up to the cylinder to be cleaned, nozzle pipes for spraying the brush roller with washing liquids, feeds for the washing liquids and a control of the individual functions. If there are several washing devices in a printing press, they can be controlled by a central control unit, which enables remote control of the washing devices from a central point.

The major disadvantage of these known, automated pressure cylinder washing devices is that the wash sequence programs are not variable. For example, for the individual washing devices, the duration of the cleaning process, the quantity metering of the washing liquids and, above all, the time course of the washing liquid metering, as well as the mechanical sequence of the cleaning process for the cleaning conditions to be expected as a rule, are preset.

Various operating parameters, for example the rotation speed of the cylinder during the cleaning process, the fact whether there is contact with the printing material cylinder and whether this contact occurs with the beautiful side or the opposite side of the printing material, the production volume since the last washing process, the position of the cylinder in the The order of printing or the paper quality naturally have a great influence on the necessary duration of the washing process, the necessary amount of liquid and above all on the exact washing process during the washing process: is the degree of soiling of the cylinder to be cleaned too high or are the preset washing program not on the existing operating parameters, the result of the washing process is unsatisfactory and leads to poor print quality when printing or requires repetition. In addition, for web-fed printing presses with printing material web, unsatisfactory washing results can lead to web breaks. It is just as unfavorable if the degree of soiling of the cylinder to be cleaned is lower than expected: the cylinder gets too wet during the cleaning process, which means a lot when printing on Waste occurs. In the case of web printing machines, it can even happen that the web breaks if the dampening is too strong. However, a web break must be avoided because it requires a new web threading process, which generally takes about 20 minutes.

Especially with larger printing presses that are equipped with a large number of printing units and other cylinders, and with web printing presses that allow many variations, for example in the substrate web guide, color assignment or cylinder position, it is difficult to overlook which cylinders have to be cleaned with which wash sequence programs. In these cases, it has so far been inevitable that the cylinders are cleaned unnecessarily often or that additional workers are required who visually determine the need for cleaning.

Based on this prior art, the invention is based on the object of specifying a method for fully automatic cylinder cleaning in printing presses with a central control system, by means of which automated washing devices on each cylinder to be cleaned can achieve optimum cleanliness with minimal amounts of washing liquid in the shortest possible time with minimal effort , whereby a web break in a possibly existing printing material web is reliably avoided.

This task is solved by a control system extension with which the operating parameters for determining the optimal wash sequence programs for each individual washing device are recorded by accessing the central printing machine control system, the optimal washing sequence programs for each individual washing device are automatically determined and the individual washing devices with the corresponding one optimal wash program can be controlled.

According to the invention, it has thus been recognized that each individual cylinder to be cleaned, as well as the special cleaning conditions on this cylinder, are recorded for themselves and an individually coordinated wash sequence program must be created and driven therefrom in order to achieve an optimal washing result. The risk of uncleanliness, overwetting or a web break is too high with preset average wash cycle programs.

Compared to manual cleaning of the cylinders, the method according to the invention, as is immediately evident, is considerably faster, safer and cheaper.

There are particular advantages if a washing process central computer is used as an extension of the central printing press control system. This central computer can optionally communicate with the various levels of the printing press control system and thus access the data necessary to determine the optimal wash cycle programs. The determination of the optimal washing sequence programs and the control of the individual washing device is then carried out from this central computer.

For the sake of simplicity, the determination of the optimal wash sequence program can be carried out by choosing the best approximation from a number of permanently preset sets of wash sequence programs, but it is also preferably possible for the wash sequence programs to be calculated individually or in groups by means of an algorithm from the recorded operating parameters be determined.

The speed of rotation during the washing process has a significant influence on the parameters to be selected for the optimal washing program, so it is advantageous that this speed of rotation is taken into account when determining the washing program.

The printing volume of the printing machine, which was at the time of the start of the washing process, is also responsible for the degree of soiling of the cylinder to be cleaned and can expediently be taken into account when determining the optimal washing sequence program.

According to a preferred embodiment of the method according to the invention, the presence of a substrate-cylinder contact during the cleaning process is taken into account as an operating parameter when determining the optimal wash sequence program; it can be advantageous that the fact whether the fine side or the opposite side of a paper web touches the cylinder is also taken into account: the surface properties of the paper web are of course essential for the contamination rate of the cylinder to be cleaned.

Furthermore, it is advantageous to take into account the paper type, possibly classified according to the manufacturer, and the color type as operating parameters when determining the wash sequence programs; both operating parameters have a significant influence on the pollution rate and the degree of difficulty in removing the pollution; For the paper type, think for example of the dustiness and pick resistance, the compatibility with washing liquid and especially the water compatibility of the paper; in the case of the color type, for example, in terms of speed and washability.

The cylinder position in the printing sequence can also be taken into account as an operating parameter when determining the wash sequence program. This is advantageous, for example, in the case of paper as a printing material, since experience has shown that the largest amount of paper fibers is plucked off when the first paper-cylinder contact is made, which then attach to the cylinder. However, the fact whether printed or unprinted printing material comes into contact with the cylinder is also significant for the type and amount of contamination.

The direction of rotation of the cylinder during the washing process is preferably also taken into account as an operating parameter when determining the optimal washing sequence program. Since the automated washing devices generally do not work symmetrically with respect to the direction of rotation of the cylinder to be cleaned, the direction of rotation of the cylinder during the washing process has an influence on the washing result. It is therefore advantageous to take this operating parameter into account in the wash cycle program.

With web printing machines, there are further advantages if the wrap angle of the printing material web around the cylinder to be cleaned is taken into account as an operating parameter for determining the optimal wash sequence program during washing: The wrap angle of the printing material web has a great influence on the amount of liquid that flows from the web from the cylinder to be cleaned is lifted off and discharged. This in turn is decisive for the risk of a web break. On the other hand, the web with the cleaning liquid also takes part of the cylinder contamination, which has a positive effect on the washing result. Finally, both effects have an effect on the amount of liquid that remains on the cylinder and thus possibly indirectly on the amount of waste when printing on. The substrate web wrap angle of the individual cylinders is determined by the web guide path and the cylinder position in the printing unit, so that the operating parameter "wrap angle" can be determined by accessing the data on the web guide path and on the machine position.

• a) 0 Grad b) bis ca. 5 Grad und c) über ca. 5 Grad erkannt

werden.To determine the optimal wash cycle programs, however, it is usually sufficient if only paper web wrap angle ranges are identified; this can preferably look like three paper web wrap angle ranges, namely:

• a) 0 degrees b) up to about 5 degrees and c) detected about 5 degrees

will.

The amount of dampening water is preferably also recorded and taken into account as an operating parameter for determining the wash sequence programs. The amount of dampening water used significantly influences the build-up of the deposits on the cylinders.

There are particular advantages if the correct time for the start of each washing process is determined and then each washing process is started automatically at precisely this or the next possible time: It is even possible to clean each individual cylinder to be cleaned at individual washing intervals, or at The next opportunity to clean all cylinders or individual cylinder groups. It may also be correct to clean one or more cylinders "too early"; the right time for cleaning is determined in any case taking into account all relevant operating parameters, which do not have to be exhausted in determining the degree of soiling, but which can also include production breaks, for example, which are due to the production process.

The determined wash sequence programs can expediently be checked and corrected manually by the printing press control system, for example from a central control center.

In the case of a blanket cylinder, the fact whether this blanket cylinder was involved in the printing with ink guidance can advantageously be taken into account as a further operating parameter in the creation of the wash sequence program. It is immediately clear that the contamination rate of this blanket cylinder depends very much on whether it was printed with or not.

Finally, the fact whether the cylinder to be cleaned has come into contact with printed or unprinted printing material can expediently also be taken into account as operating parameters when the wash sequence program is created.

The method according to the invention detects the operating parameters in order to determine the optimal washing sequence programs for each individual washing device, that is to say at a point at which all process parameter data, be it as a specification or as a feedback from the machines, are already available in an ordered manner. An operator who controls the entire printing press, for example via a central control station, no longer has to worry about wash sequence programs; these are determined fully automatically, after which the individual washing processes can also be initiated fully automatically.

Particular advantages result from the design of the invention according to claim 21: In web printing machines with guide rollers, which are only passed through by the printing material web after the blanket cylinders, it is very advantageous if they are not equipped with their own automated washing devices or detergent application devices, optionally with one each for each substrate side must be equipped: By accessing the central printing press control system according to the invention, the last automated washing device in the direction of substrate movement in front of the guide rollers, which is assigned to a cylinder in contact with the substrate web, can be selected; if necessary, the last automated washing device in front of the guide rollers can also be selected for each of the two printing material web sides.

For this selected automated washing device, a washing program is then determined, with which the automated washing device is controlled and which moistens the printing material web with cleaning liquid, taking into account the current cleaning requirements of the guide rollers, which are also determined by access to the central printing machine control system. The thus moistened printing material web runs from the blanket cylinder, to which the selected automated washing device is assigned, to the guide rollers to be cleaned. The guide rollers to be cleaned are controlled, braked or driven according to the invention either manually or automatically from the central control station during their contact with the moistened printing substrate web in order to produce a slip between the guide roller and the printing substrate web. If the slip process is automated, the time and the duration of the slip courses of the individual guide rolls to be cleaned are automatically determined and used by accessing the data available in the central control system in order to optimize the overall process (washing of all guide rolls).

The desired cleaning effect for the guide rollers to be cleaned results from the slippage and the fact that the printing material web has been moistened with cleaning liquid in a defined manner. At least some of the guide rollers can be cleaned fully automatically within the scope of the method according to the invention without additional effort and without having to assign an automated washing device or for each printing substrate web a detergent application device or, if necessary, with one side for each printing substrate web.

The detergent application device can be arranged both before and after the blanket washing device.

The following examples reveal further advantageous features and special features of the invention, which are described in more detail with reference to the illustrations.

Figur 1

Eine Schemazeichnung einer Satelliteneinheit einer Zeitungsrollendruckmaschine,

Figur 2

eine Schemazeichnung einer anderen Satelliteneinheit einer Zeitungsrollendruckmaschine,

Figur 3

eine Schemazeichnung einer Akzidenzrollen-Druckmaschine,

Figur 4

eine Schemazeichnung einer Bogendruckmaschine.

Figur 5

eine Schemazeichnung einer Satelliteneinheit einer Zeitungsrollendruckmaschine mit Leitwalzen.

Show it:

Figure 1

A schematic drawing of a satellite unit of a newspaper roll printing machine,

Figure 2

a schematic drawing of another satellite unit of a newspaper roll printing machine,

Figure 3

a schematic drawing of a commercial web press,

Figure 4

a schematic drawing of a sheet printing machine.

Figure 5

a schematic drawing of a satellite unit of a newspaper roll printing machine with guide rollers.

FIG. 1 shows a satellite unit 1 of a newspaper web offset press in which two paper webs 5a and 5b are each printed in 1 + 1 printing.

The satellite unit 1 is in the print-down position. It essentially consists of an impression cylinder 2, four blanket cylinders 3 and four printing plate cylinders 4. In the example shown, the paper webs 5a, 5b are printed in print-on position without contacting the impression cylinder 2 between two blanket cylinders 3 in each case. The blanket cylinders 3 are now cleaned in the print-down position by the washing devices 9 assigned to each blanket cylinder 3. It is now clear that the washing devices 9 each have different operating parameters, as a result of which the washing sequence programs of the washing devices 9 differ from one another for an optimal result Must: Two of the four blanket cylinders 3 have paper contact during the cleaning process - there may be a risk of a web break there - and thus there are completely different cleaning conditions than with the other two blanket cylinders 3. The operating parameters that are important here are, for example: paper web -Cylinder contact, wrap angle, rubber-rubber pressure instead of rubber-steel pressure, circumferential speed of the blanket cylinder 3, as well as the amount of ink and fountain solution. The operating parameters: type and quality of the paper web and the color, as well as the fact whether the blanket cylinder cleaning takes place during or after the production also to be considered. The direction of rotation of the blanket cylinder 3 during cleaning is not uniform. In this example, the method according to the invention therefore makes it possible to optimally create the individual washing sequence programs for the individual washing devices 9, as a result of which the individual washing devices 9 with individually adapted washing parameters, such as:
Detergent amount, amount of water, intensity and total duration of the mechanical cleaning process, but above all with the individually adapted time course of these washing parameters can be optimally controlled.

Figure 2 shows the same satellite unit of a newspaper web offset machine with a different web guide. The paper web 5 is printed here in 4 + 0 printing. Again, it is clear that two of the four blanket cylinders 3 are in contact with paper during the cleaning process, but the remaining two blanket cylinders 3 are not. In this example, the paper web 5 is printed between the impression cylinder 2 and the four blanket cylinders 3 in the print-on position; so it is printed between rubber and steel. The printing plate cylinders 4 and the washing devices 9 have the same function here as in the satellite unit 1 of FIG. 1. The same operating parameters for determining the optimal washing sequence programs are also interesting here, but it is clear that the operating parameters and therefore also the optimal washing sequence programs for the washing devices 9 here are very different from the operating parameters in the example in FIG. 1.

However, there are not only different operating parameters of the individual cylinders to be cleaned within a satellite unit 1 during one and the same production; two successive productions with, for example, different web guiding paths can again significantly modify the operating parameters of the cylinders to be cleaned on the same satellite unit 1.

FIG. 3 shows two web guiding options in a commercial web press: In the upper illustration, a paper web 5 is printed in 5 + 5 printing and is guided in a straight line through the printing units 10, 11, 12, 13 and 14. These printing units each consist essentially of two blanket cylinders 3 and two printing plate cylinders 4, with the blanket cylinders 3 each being assigned a washing device 9. The lower representation in FIG. 3 shows that two paper webs 5a and 5b can optionally be used. The paper web 5a is given a 1 + 1 print in the printing unit 15, and the paper web 5b is given a 4 + 4 print in the printing units 16, 17, 18 and 19. As can easily be seen, the most interesting operating parameter in FIG. 3 is the order of the printing unit occupancy: printing unit 10 is the first to come into contact with paper web 5, as a result of which an above-average amount of paper fibers are plucked from fresh paper web 5. For this purpose, the printing unit 11, which is in second place, comes into contact with freshly printed paper. The situation is different with the printing units 15 and 16, which are each at the first printing point. The wash sequence programs of the washing devices 9 in the printing units 11 and 16 must therefore be different. In a commercial web press, it is also customary to work with changing paper types and ink types, which means that the paper quality and the ink quality are primarily important operating parameters for determining the optimal wash sequence programs.

FIG. 4 shows two snapshots of the relevant parts of a sheet-fed printing machine 20: The upper picture shows schematically how sheets of paper 21 are printed in 5 + 0 printing. The sheets of paper 21 pass through one Sheet feeder 22 on the impression cylinder 2, are each printed by the blanket cylinder 3, which is connected to the printing plate cylinder 4, transported via the transport cylinder 23 to the next impression cylinder 2, until finally the printed paper sheet 21 is finally placed in a sheet delivery 24. In the lower part of FIG. 4, the paper sheets 21 are given a 4 + 1 print: after the first impression cylinder 2, the paper sheets 21 pass through a transport cylinder 23 and a sheet turning drum 25, as a result of which the previous back side of the paper sheet 21 is subsequently printed. Accordingly, the same applies here as for the commercial web press: the sequence of the printing units in the printing process is essential for the wash sequence programs of the washing devices 9. moreover, it is particularly easy, especially in sheet-fed machines, to change the paper quality at very short intervals, which likewise has a considerable influence on the optimal washing sequence programs of the washing devices 9. Of course, other operating parameters such as cylinder speeds, production quantities, fountain solution quantities, speed and quantity of ink are also important for the creation of the optimal wash sequence programs.

FIG. 5 illustrates the web guidance of a newspaper roll printing machine from the last satellite unit 1 to the guide rollers 26, which transport the finished printed paper web 5 for further processing. The guide rollers 26 are not with automated washing devices in this example 9 equipped; the printing material web has also not been provided with an additional automated detergent application device.
Due to the intimate contact with the printed paper web 5, however, it is necessary from time to time to clean the guide rollers 26 as well, depending on the operating parameters such as the print run, type of printing ink, type of paper web etc. In the example shown, this is done by means of the washing device 9 ', which is arranged on the blanket cylinder 3': The blanket cylinder 3 'is the last cylinder with an associated washing device 9', which is in contact with the paper web 5 before it is guided over the guide rollers 26. By accessing the central printing press control system, the control system extension according to the invention recognizes that the blanket cylinder 3 'is the last cylinder with an associated washing device 9' and controls the washing device 9 'with a corresponding washing sequence program in order to clean the guide rollers 26: by the washing device 9' the blanket cylinder 3 'and thus indirectly the paper web 5 is moistened with cleaning agent which carries the cleaning agent to the guide rollers 26. The guide rollers 26, which are to be cleaned, are braked as they pass through the paper web 5 in order to produce a slip. The wiping effect of this slip between the guide roller 26 on the one hand and the paper web 5 moistened with cleaning agent on the other hand cleans the guide roller 26 with good success. Within the scope of the invention, the best wash sequence program for an optimal washing result is selected or determined fully automatically by accessing the data of the relevant operating parameters present in the central control system of the printing press. The embodiment according to the invention shown in FIG. 5 thus represents a simple and inexpensive, but nevertheless effective variant of the method according to the invention If required, detergent can be applied to both sides of the substrate without additional effort.

The method according to the invention thus makes it possible to achieve cylinder cleaning in printing presses which produces optimum cleanliness in the shortest possible time without the risk of a web break in machines with webs. Even cleaning while the machine is in operation is possible.

With the invention, a truly fully automatic cylinder cleaning is thus achieved for the first time, in which the operator no longer has to worry about the cleaning process and the optimal time for cleaning.

Reference list

1

Satellite unit

2nd

Impression cylinder

3rd

Blanket cylinder

4th

Printing plate cylinder

5

Paper web

9

Washing facility

10-19

Printing units

20th

Sheet printing machine

21

Sheets of paper

22

Sheet feeder

23

Transport cylinder

24th

Sheet boom

25th

Sheet turning drum

26

Guide roller

Claims (21)

1. Procedure for the fully automatic cleaning of cylinders in printing machines equipped a with central control system, using a separate automated washing unit for each cylinder,
   wherein
   the central control system is extended in such a way as to enable

   a) the operating parameters - necessary for the determination of the optimal wash-cycle program of each separate washing unit - to be collected by acceding to the central control system of the printing machine,

   b) said optimal wash-cycle program for each separate washing unit to be automatically determined,

   c) the operation of each separate washing unit to be controlled by its own optimal wash-cycle program.
2. Procedure according to claim 1,
   wherein
   a wash-cycle central computer is used as an extension to the central control system of the printing machine.
3. Procedure according to claim 1,
   wherein
   the determination of the optimal wash-cycle program of each separate washing unit is brought about by selecting the closest approximation out of a number of preset sets of wash-cycle programs.
4. Procedure according to claim 1,
   wherein
   the optimal wash-cycle program of each separate washing unit is generated, as a function of the operating parameters collected, by means of an algorhythm.
5. Procedure according to claim 1,
   wherein
   the rotational speed of the cylinder to be cleaned during said wash cycle is taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
6. Procedure according to claim 1,
   wherein
   the time of said wash cycle, and possibly the time interval elapsed since the time of the last wash cycle, are taken into account as operating parameters when determining the optimal wash-cycle program of each separate washing unit.
7. Procedure according to claim 1,
   wherein
   the presence of stock of cloth coming into contact with the cylinder during said wash cycle is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
8. Procedure according to claim 1,
   wherein
   the presence of paper coming into contact with the cylinder during said wash cycle - and particularly which side of the paper, the face or reverse side - is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
9. Procedure according to claim 1,
   wherein
   the type of paper is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
10. Procedure according to claim 1,
    wherein
    the type of colour is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
11. Procedure according to claim 1,
    wherein
    the cylinder position with regard to the printing sequence is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
12. Procedure according to claim 1,
    wherein
    the sense of cylinder rotation is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
13. Procedure according to claim 1,
    wherein
    the quantity of dampening water used during the printing process is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
14. Procedure according to claim 1,
    wherein,
    in the case of roller printing machines, the looping angle of the run of cloth around the cylinder is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
15. Procedure according to claim 14,
    wherein
    the cloth guide path data are used to determine the looping angle of the run of cloth.
16. Procedure according to claim 14,
    wherein
    three different stock looping angle zones:

    a) 0 degrees

    b) up to about 5 degrees and

    c) more than about 5 degrees

    are detected.
17. Procedure according to claim 1,
    wherein
    the fact whether or not, in the case of a rubber blanket cylinder, said cylinder - as part of the printing process - is a colour-carrying cylinder, is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
18. Procedure according to claim 1,
    wherein
    the fact whether the cylinder to be cleaned has come into contact with either printed or unprinted stock of cloth is to be taken into account as an operating parameter when determining the optimal wash-cycle program of each separate washing unit.
19. Procedure according to claim 1,
    wherein
    the ideal start time for each wash cycle is determined, with each wash cycle being automatically released eiterh precisely at said ideal start time previously determined or as soon as possible thereafter.
20. Procedure according to claim 1,
    wherein
    the wash-cycle programs previously determined can be checked and corrected by hand from the central control system of the printing machine.
21. Procedure according to either of the preceding claims,
    wherein,
    in the case of roller printing machines with guide rollers with at least one superimposed rubber-blanket cylinder, at least part of said guide rollers require cleaning by

    a) acceding to the central control system of the printing machine with a view to selecting either the last automated upstream washing unit directly ahead of the guide rollers in the feeding direction of the cloth run, or the last automated upstream washing unit directly ahead of each of the two cylinders, in the feeding direction of the cloth run, one of which presses against the face of the cloth and the other against the reverse of the cloth,

    b) determining at least one wash program for each of said automated washing units by which exactly that quantity of cleaning liquor is sprinkled onto the run of cloth that corresponds to the moisture requirement of the guide rollers as determined in a continuous manner by the central control system of the printing machine,

    c) regulating and controlling said selected automated washing unit(s) by means of said wash program(s) thus determined,

    d) enabling the guide rollers - with a view to producing slippage between the guide roller and the run of cloth - to be controlled, stopped or driven by hand or from the central control panel while in contact with the dampened run of cloth.

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