EP1661702A1 - Process and apparatus for cleaning of cylinders in a printing machine - Google Patents

Abstract

Method for cleaning cylinders of a printing machine using an automated washing machine comprises influencing the start and/or selection of the washing discharge program by the signals of a sensor (3) which scans the surface of the cylinder or printed material (4) leaving the cylinder, estimating the degree of dirt of the cylinder and/or temporary progression of the sensor signals from the sensor signals and selecting the washing discharge program. An independent claim is also included for a device for cleaning cylinders of a printing machine using an automated washing machine. Preferred Features: The start and/or selection of a washing discharge program is influenced by the signals of the sensor in such a way that the start of the washing program is delayed or automatically carried out only from a prescribed or pre-adjusted threshold value of the degree of dirt.

Description

The invention relates to a method and a device for cleaning cylinders of a printing machine by means of an automated washing device according to the preambles of claims 1 and 14.

In particular newspaper presses, commercial web presses and sheetfed presses of all printing processes, such as offset printing, anilox offset, Intaglio printing, flexo printing, anilox flexo printing and gravure printing are addressed by printing presses. Under the cylinders to be cleaned are all rollers, rollers and cylinders of a printing press, in particular blanket cylinder, impression cylinder, plate and forme cylinder, cooling rollers, guide rollers and ink rollers to understand.

The mentioned printing machines have in common that an intensive contact between the printing substrate and the cylinder is necessary for the guidance, for the processing and for the drive of printing material sheets or printing material webs. This results in paper as printing material on the cylinders deposits of paper dust (fibers, coating, fillers, etc.), ink and optionally powder dusting. These deposits affect the cylinders in their functionality; For example, deposits on blanket cylinders in offset printing cause the dot sharpness of the print to be lost and some print sections to no longer print correctly. Especially with blanket cylinders, however, the deposition rate is particularly high due to the high viscosity and adhesion of the ink. For the print quality and the operational safety, it is therefore essential that the mentioned cylinders are regularly freed from contamination.

In addition to the still found cleaning of cylinders by hand, automated washing devices have been used for some time for this purpose, as described for example in EP 0 419 289 A2. Such an automated washing device essentially consists of a brush roller which can be moved up to the cylinder to be cleaned, nozzle tubes for spraying the brush roller with washing liquids, feeds for the washing liquids and a controller for the individual functions. If several washing devices are present in a printing machine, then they can be controlled by a central control unit, which enables remote control of the washing devices from a central control panel.

EP 0 654 350 A1 discloses a method for fully automatic cylinder cleaning in printing presses with a central control system. According to this prior art, the control system is extended by a control function, wherein a plurality of wash sequence programs is stored and the selection and optionally the time of starting a wash cycle program for a particular washing device is automatically determined by accessing the data of the central printing machine control system.

However, especially in commercial, web and sheet-fed presses, cylinder cleaning has usually been carried out automatically after a manual start and selection option for the individual washing programs, ie. H. not fully automatic.

This has led in practice to the fact that the cylinders are sometimes cleaned too often, but usually with more intensive wash cycle programs than necessary; because too weak a wash program, for example, in a blanket cylinder dissolves the color on the same only, which does not reduce the adhesion of the ink sufficiently and, for example, when washing in a web offset printing press can lead to a dreaded web tear of the printing substrate.

However, a too-intensive or earlier than necessary started wash sequence program can lead to problems because the degree of contamination of the cleaned cylinder does not correspond to the amount of applied washing liquids and accordingly a certain amount of washing liquid is not bound. Instead, in the worst case, this takes place as a spray and in the form of splashes in the surroundings of the cylinder and on other machine parts. In particular, a washing liquid spray can condense at various points of the printing press, possibly collect there and drip onto the substrate; this then leads to the production of waste paper, which can occasionally occur during production, d. H. is almost impossible to sort out.

When printing progress cleaning there is a risk that the substrate too much washing liquid, especially water absorbs, and consequently the risk of tearing, in web presses, in turn, the risk of production stoppage.

The present invention is therefore based on the object for the first time reliably avoid unnecessary or unnecessarily intensive washing operations in a method and apparatus of the type mentioned above and to optimize the timing and / or the intensity of the washing process.

This object is achieved by a method having the features of patent claim 1 and by a device having the features of patent claim 14.

Advantageous developments of the method will become apparent from the claims 2 to 13; preferred embodiments of the device are laid down in the claims 15 to 27.

Thus, according to the present invention, as before, there is an automated washing device which is controlled by a controller with a washing sequence program. The wash cycle program may be fixed, or it may be several different, fixed predetermined wash sequence programs stored in the controller. Depending on it can too be advantageous that the controller generates based on data of current boundary conditions due to a predetermined algorithm, a wash process program itself, so as not to be limited to a limited number of predetermined wash sequence programs. The start of the wash cycle program and / or the selection of one of several wash cycle programs can be done automatically or manually, for example, a manual start is only released when the washing of a cylinder makes sense. In this case, an automatic delay of a manual start can be used, whereby the controller notices the manual start command and then implements the start at the earliest possible reasonable point in time. In this case, mixed forms are also conceivable, for example, in that the controller automatically corrects a manual selection and a manual start of a wash cycle program with regard to the selection.

All variants have in common that the main difference to the prior art, a sensor cooperating with the control is provided, which scans the surface of the cylinder to be cleaned or the printing material leaving this cylinder without contact. This may, for example, be a known monitoring sensor for a closed-loop control of the color density control of the printing press, which may be present anyway in the printing press, the signals of which are additionally used for the method according to the invention.

The advanced washer control then estimates based on the signals received from the sensor, the degree of contamination of the cylinder to be cleaned, which depends on this estimated current degree of contamination, the selection of the most suitable wash sequence program and / or the most suitable starting time for the start of the wash cycle program is determined. According to a variant of the invention, the sensor signals are evaluated by the washer control such that from the time course of the sensor signals a forecast for the degree of pollution at a given future time or a prognosis for the course of the pollution level is created and this forecast for the selection and / or the most appropriate start time of the wash cycle program is used. In this case, mixed forms are also covered by the invention, Thus, the consideration of the estimated current degree of contamination in addition to the consideration of the predicted degree of contamination at a future time or the course of the degree of contamination for the selection and / or the most favorable start of a wash cycle program.

In this case, it is advantageous if further operating parameters of the printing press for the selection or the start time of the wash sequence program are taken into account, such as in particular the time of a roll change or any planned production breaks.

The inclusion according to the invention of a sensor for estimating or predicting the degree of contamination naturally provides a much higher reliability of the estimated or predicted data compared to a typical estimation or prognosis only on the basis of the known machine and production data; especially since the nature of the contamination of the cylinders of a printing press also depends on how the responsible printer operates the printing press.

The start and / or selection of the wash cycle program can be influenced by the signals of the sensor such that the start of a certain wash cycle program is released, delayed, or performed automatically only after a threshold of the estimated contamination level. The threshold value can be predetermined here; On the other hand, it is particularly advantageous if the threshold value can be preset, that is to say it can be adapted to the respective conditions on site. As long as only one wash cycle program is present in the controller, or as far as the wash cycle program is generated in the controller by means of an algorithm in real time, according to this embodiment of the invention, then when a predetermined or preset threshold of the basis of the sensor signals estimated pollution level is reached or exceeded , the wash sequence program is started, generated or released, for example, for a manual start, possibly with an automatically generated delay. If the control of the washing device or washing devices holds several washing sequence programs stored, According to the estimated or predicted degree of soiling, a specific wash sequence program can be selected. In this case, the invention can also serve for the fact that in the case of several graduated-intensity wash sequence programs, one or more wash sequence programs for, for example, a manual start are only released when one of a plurality of threshold values assigned to the wash sequence program is reached.

In order to ensure that the waste produced during a cleaning process remains as low as possible, it may also be advantageous not to wait until the aforementioned threshold for the contamination of the cylinder to be cleaned is reached or exceeded, ie waste before the start of a wash cycle program but when based on the signals from the sensor and the timing thereof, a threshold time is predicted at which a predetermined or presettable threshold of the estimated level of contamination is exceeded while a wash schedule is started at a start time approximately equal to the time duration that the selected wash schedule needs to process before the threshold time. Depending on how the time differential of the course of the estimated degree of contamination, for example, increases, it may be useful, especially in a foreseeable role change shortly before reaching the threshold, the start time earlier or possibly later, so to choose closer to the threshold time.

Irrespective of this, the start of a wash cycle program can in any case be advanced in time if, based on the sensor signals and their course, an increase in the degree of contamination that accelerates over time is forecast.

Even if the control of several washing devices present in a printing press takes place fully automatically from the control station of the printing machine, the inventive estimation and prediction of the degree of soiling of the individual cylinders to be cleaned can be corrected by means of a sensor or refined from the other operating parameters obtained prognosis on the degree of contamination of the cylinder to be cleaned can be used.

Both in printing presses with central control station, but also in other printing machines in which, for example, the path of the printing material is fixed by the printing press, it is advantageous if the start and / or selection of a wash program in addition to the consideration of the invention estimated by means of the sensor signals or predicted degree of contamination taking into account further parameters, such as the rotational speed of the cylinder to be cleaned, the presence of a cylinder substrate contact during cleaning, the printing material type, ie usually the paper type, the color type or the amount of fountain solution used in the printing done.

As already mentioned above, the consideration of the sensor signals according to the invention takes place in such a way that a wash cycle program optimized for the cleaning process and / or the time for its startup is determined not with regard to the cleaning result but with respect to the minimum required time duration. This takes into account the predicted future course of the degree of contamination and taking into account further production data of the printing press, so in particular a previously known production interruption due to a paper roll change or due to a standstill in a conversion to other printing plates. Because with already existing production stoppages or downtimes of the printing press, the washing devices can work while they cause a minimized or no waste. This development of the invention is to be understood against the background that the cleanliness of the cylinder of a printing press, and thus ultimately the printed image must not always be optimal, but only within a certain tolerance to find. Only if the degree of contamination exceeds a certain threshold, at which the printed image then becomes too bad, must be acted; but even then, depending on the boundary conditions, it is not always the best to achieve the optimum cleaning result - for example, if you do not print too long until the next production standstill is due - but in this case, for example make sense to clean only weak, but this requires very little time to keep the print image in the tolerable range until the next production stop. A similar optimization consideration leads to the embodiment of the invention, which is advantageous even under certain boundary conditions, according to which complete cleaning is already carried out by starting a corresponding wash cycle program before the level of contamination that is still tolerable is reached, so that the degree of contamination and, consequently, the print quality until the next scheduled production shutdown is then completed Stay better on average.

As a sensor, an already present on the printing machine monitoring sensor is particularly preferably used, in particular a monitoring sensor for the color density control of the printing press; because this interacts with the color density control in any case so that it forms a control loop with this, its signals, which detects the printed image on the printing paper leaving the cylinder to be cleaned by optical scanning, are used as a control variable for the color density. To Reahsierung of the invention then only the control of this monitoring sensor with the control of the automated washing device must be connected so that the signals of the monitoring sensor according to the invention act on the start and / or selection of Waschablaufprogamms for the washing device.

The estimation of the degree of contamination is preferably carried out programmatically by comparing the signals of the sensor with a stored plurality of sensor signal patterns, wherein for each stored sensor signal pattern a typical degree of contamination is deposited and insofar as created by means of an algorithm best match of the measured sensor signal pattern with a the stored sensor signal pattern allows the estimation of the degree of contamination according to the invention.

The inventively present sensor can be an optical sensor, in particular with a (digital) camera, with the example, a dot magnification in the print image on the cylinder to be cleaned leaving printing material can be optically detected, or with a laser.

As an alternative to an optical principle in the sensor according to the invention, the scanning of the surface of the cylinder or the printing material to be cleaned can be effected capacitively or by means of sound wave reflection or sound wave transmission.

The control of the device according to the invention can be integrated as a software module in the control of the car wash or in a control of other already existing control systems, such as the control of the color density. This saves costs and maintenance.

An embodiment of an apparatus according to the invention will be described below with reference to the accompanying drawings and explained in more detail.

Show it:

FIG. 1

the basic structure of an example of a system according to the invention;

FIG. 2

a flow chart for the operation of the embodiment of Figure 1;

FIG. 3

a schematic representation of the visualization of a pressure point increase.

In Figure 1, the basic structure of an embodiment of a device according to the invention is shown schematically. A washing device 1 is controlled by a controller 2, the controller 2 being influenced by the signals of an imaging sensor 3, which optically scans a paper web 4 serving as printing material, via a sensor signal evaluation electronics 5. The sensor 3 is a color density sensor head that moves across the paper web 4 passing below it and measures the color density of the printed image. The sensor signal evaluation 5 calculates the manipulated variable for the control loop of a color control 6 of the printing press, and is therefore already available at the printing press. At the same time, the sensor signals from the transmitter 5 are diverted to the controller 2 of the washing device 1, wherein optionally - indicated by broken lines - a signal path 7 is set, so that the controller 2, which is realized in the present case as a software module, can act on the sensor signal evaluation electronics 5 to generate the data required for the control of the washing device 1 and in particular the selection of washing sequence programs and the start of the same.

FIG. 2 is a flow chart illustrating the operation of the structure shown in principle in FIG. The printed by the imaging sensor 3, here a CCD camera printed image on the paper web 4 and the corresponding digital signals are first divided into the sensor signal transmitter 5 in the hues of black, cyan, magenta and yellow, after which separated for these colors The controller 2 takes the detected pressure point size as a measure of the degree of soiling of the cylinder to be cleaned and calculates the time differential dg / dt in parallel from the time profile of the detected pressure point quantities, in order to use this together with the currently measured pressure point size a prognosis for the future increase in pressure point size.

If a certain limit value of the pressure point size, which is adjustable in the present case, is reached, this applies in the exemplary embodiment illustrated here as a threshold value for the degree of contamination at which the corresponding cylinder of the printing press must be cleaned. Therefore, the controller 2 compares the currently measured pressure point quantities with the set limit value and calculates, based on the calculated prognosis for the future course of the pressure point increase in size, the threshold time point at which the pressure point magnitude is likely to exceed the set limit value. This calculation is performed separately for all the colors, after which the respective threshold timings are again set in relation to each other and then the time at which a cleaning of the cylinder or of the plurality of cylinders controlled by the present controller 2 is calculated is calculated. Taking into account further parameters of the printing press, it is then automatically decided on the basis of this message (this process is no longer illustrated in FIG. 2) when and with which wash cycle program the washing device 1 is started.

FIG. 3 again schematically illustrates the increase in the pressure point size which is used as a measure of the degree of soiling of a blanket cylinder.

Claims (27)

Method for cleaning cylinders of a printing press by means of at least one automated washing device, wherein the washing device is controlled by a controller with a wash program, while the start of the wash program and / or the selection of one of several wash programs automatically, automatically delays or manually,
characterized,
in that the start and / or the selection of the wash program is influenced by the signals of a sensor which scans the surface of the cylinder to be cleaned or the printing material leaving this cylinder in a contactless manner.
in that the controller generates from the sensor signals an estimate of the degree of soiling of the cylinder to be cleaned and / or from the time profile of the sensor signals a prognosis for the degree of contamination at a specific future time or a prognosis for the course of the degree of soiling
depending on the estimated current degree of contamination and / or depending on the predicted degree of contamination, the selection of the most suitable Waschablaufprogamms takes place and / or the most suitable starting time is determined. Method according to claim 1,
characterized,
that the start and / or the selection of such influences of a washing sequence program on the signals of the sensor, that only after a predetermined or pre-settable threshold value of the estimated degree of contamination of the starting released a specific washing sequence program, delayed performed or is performed automatically. Method according to one of claims 1 or 2,
characterized,
in that the start and / or selection of a wash cycle program is influenced by the signals of the sensor in such a way that a threshold time point is predicted at which a predetermined or presettable threshold value of the estimated contamination level is exceeded and a wash program is started at a start time which is approximately the amount of time the selected wash schedule needs is before the threshold time. Method according to one of claims 1 to 3,
characterized,
that the start and / or the selection of such influences of a washing sequence program on the signals of the sensor, that the start of a washing sequence program is brought forward in time when a is accelerating with time, increase the degree of contamination is predicted. Method according to one of claims 1 to 4,
characterized,
in that the start and / or the selection of a wash cycle program, in addition to the estimated degree of soiling, are also influenced by further parameters, such as the rotational speed of the cylinder to be cleaned, the presence of a cylinder substrate contact during the washing process, the type of substrate, the type of ink or the amount of fountain solution used during printing. Method according to one of claims 1 to 5,
characterized,
that the start and / or the selection of a wash cycle program is influenced by the signals of the sensor such that taking into account the predicted future course of contamination and taking into account further production data of the printing press, such as in particular a production interruption due to a paper roll change or due to a conversion to other printing plates, not with regard to the cleaning result, but with regard to minimized time required for the duration of the cleaning process optimized wash cycle program and / or the time for its start is set. Method according to one of claims 1 to 6,
characterized,
in that a monitoring sensor for the ink density control of the printing press is used as the sensor. Method according to one of claims 1 to 7,
characterized,
that the estimation of the degree of contamination by comparison of the signals of the sensor with a stored plurality of sensor signal patterns. Method according to one of claims 1 to 8,
characterized,
that the scanning of the surface of the cylinder or the printing material to be cleaned is done optically, in particular with a camera or a laser. Method according to claim 9,
characterized,
in that the sensor visually detects a dot enlargement in the print image on the printing stock leaving the cylinder to be cleaned. Method according to one of claims 1 to 8,
characterized,
in that the scanning of the surface of the cylinder or of the printing material to be cleaned takes place capacitively or by means of sound wave reflection or transmission. Method according to one of claims 1 to 11,
characterized,
that the selection of a wash cycle program is effected in that the controller generates a wash cycle program based on a predetermined algorithm taking into account the sensor signals. Method according to one of claims 1 to 11,
characterized,
that the selection is made of a washing sequence program of a number of predetermined washing sequence programs. Apparatus for cleaning cylinders of a printing machine, comprising at least one automated washing device (1) and a control device (2) for the automated washing device, which control controls the washing device with an automatically or manually selectable and automatically, automatically delayed or manually startable wash cycle program,
characterized,
in that a sensor (3) interacting with the control is also provided, which scans the surface of the cylinder to be cleaned or the printing material (4) leaving this cylinder without contact, and in that the controller is designed to estimate the degree of soiling from the sensor signals of the cylinder to be cleaned and / or from the time course of the sensor signals generates a prognosis for the degree of pollution at a specific future time or a prognosis for the course of the degree of pollution, according to which it selects the most suitable washing sequence program and / or the most suitable starting time depending on the estimated current degree of contamination and / or depending on the predicted degree of contamination. Device according to claim 14,
characterized,
that the controller (2) is such designed that performs that it releases the start of a specific washing sequence program until a predetermined or pre-settable threshold value of the abge-estimated degree of contamination, delayed or automatically performs. Device according to one of claims 14 or 15,
characterized,
that the controller (2) is configured to predict a threshold time at which a predetermined or presettable threshold of the estimated fouling level is exceeded and a wash schedule starts at a start time approximately equal to the time required for the selected wash schedule prior to Threshold time is. Device according to one of claims 14 to 16,
characterized,
that the controller (2) is configured to time the start of a wash schedule when it predicts a time-increasing rate of contamination increase. Device according to one of claims 14 to 17,
characterized,
in that the controller (2) is designed in such a way that the start and / or the selection of a wash cycle program are not limited to the estimated one Pollution degree is also influenced by other parameters, such as the rotational speed of the cylinder to be cleaned, the presence of a cylinder substrate contact during the washing process, the type of printing material, the color type or used during printing dampening water. Device according to one of claims 14 to 18,
characterized,
that the controller (2) is designed such that, taking into account the predicted future course of the degree of contamination and taking into account further production data of the printing machine, in particular interruption times due to a paper roll change or due to a conversion to other printing plates, one not with regard to Cleaning result, but with regard to the minimum possible time required for the cleaning process optimized wash schedule and / or determines the time for its start. Device according to one of claims 14 to 19,
characterized,
that the sensor (3) is a monitoring sensor for the ink density control (6) of the printing machine. Device according to one of claims 14 to 20,
characterized,
in that the controller (2) contains a stored plurality of sensor signal patterns and is configured to perform the contamination level estimation by comparing the signals of the sensor with the stored plurality of sensor signal patterns. Device according to one of claims 14 to 21,
characterized,
is that the sensor (2) is an optical sensor, in particular with a camera or a laser. Apparatus according to claim 22.
characterized,
that the sensor (3) is designed so that it optically detects an increase in dot in the printed image on the printing material (4) leaving the cylinder to be cleaned. Device according to one of claims 14 to 22,
characterized,
that the sensor (3) is a capacitive or acoustic sensor. Device according to one of claims 14 to 24,
characterized,
that the controller (2) is designed as a software module. Device according to one of claims 14 to 25,
characterized,
in that the controller (2) is designed such that it selects a wash cycle program by generating a wash cycle program based on a predetermined algorithm taking into account the sensor signals. Device according to one of claims 14 to 25,
characterized,
in that a number of predefined wash sequence programs are stored in the controller (2), while the selection of a wash sequence program takes place by selecting one of these stored wash sequence programs.

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