WO2008084361A1

WO2008084361A1 - Apparatus for cleaning cylinders in continuous printing machines

Info

Publication number: WO2008084361A1
Application number: PCT/IB2007/055330
Authority: WO
Inventors: Marco Corti; Riccardo Fumagalli
Original assignee: Finelettra International S.A.
Priority date: 2007-01-05
Filing date: 2007-12-28
Publication date: 2008-07-17
Also published as: ITBO20070006A1

Abstract

The apparatus for cleaning cylinders (C) in continuous printing machines comprises transversely with respect to the strip of paper (N) at least one bar or a pair of facing bars (8, 18) with associated nozzles (108, 118) for spraying respectively onto at least one or onto both the opposite sides of the said strip (N) advancing at a suitable speed and in contact with the cylinders, suitable quantities of a cleaning liquid with solvent, necessary for cleaning the said cylinders and has means (2) for immediate recovery of the mist and spray resulting from the action of the said bars (8, 18) and the liquid supplied by the said bar or bars along the flanks of the strip of paper, in particular if it has a width smaller than the maximum width which can be inserted in the printing machine.

Description

TITLE:

"APPARATUS FOR CLEANING CYLINDERS IN CONTINUOUS PRINTING MACHINES"

DESCRIPTION

The invention relates to an apparatus for cleaning cylinders in continuous printing machines, for example of the so-called reel type, which have rubber printing cylinders which act simultaneously on the opposite sides of a continuous strip of paper unwound from a reel. For these types of machines it is known to use apparatus situated upstream of the printing cylinder train, for supplying, when operated, onto one or onto the opposite sides of the advancing strip of paper suitable quantities of a solvent- containing cleaning liquid which is transferred from the said strip to the rotating printing cylinders in order to dilute and soften the ink thereon and the paper residue and which is then recovered together with the dirt by the same strip of paper and is removed when it passes through the drying oven which fixes the dirt on the strip of paper and evaporates the solvent which, in order to prevent the formation of explosive mixtures, must not exceed predetermined maximum quantities.

The apparatus of the known type have limitations as regards the distribution of the solvent on the paper sheet which passes through them and in particular are unable to allow regulation of the supply of solvent by the supplying means so as to determine different quantities of solvent which reach varyingly dirty zones on the cylinders of the printing machine.

The invention intends to overcome these and other limitations of the prior art, with an apparatus as described in Claim 1 and the following dependent claims, based on the following proposed solution. The cleaning liquid with solvent is supplied onto one or onto both the sides of the strip of paper in an amount related to the feeding speed of the said strip, by one or two spraying bars, each of which is divided into several adjacent sections, with respective nozzles, and these sections are supplied by respective electrovalves and means which, as well being able to be activated or deactivated, in order to adapt the active length of the bar to that of the strip of paper inserted in the printing machine, allow the said bar sections to be supplied with variable quantities of solvent so as to adapt operation of the bar or bars to the different feeding speeds of the strip of paper and so as to allow regulation of the quantity of solvent which is supplied transversely onto the said strip per unit of time, so as to be able to supply more or less solvent in the respectively more or less dirty zones of the printing cylinders to be cleaned or so as to perform microwashing methods as described further below.

Further characteristic features of the invention, and the advantages arising therefrom, will appear more clearly from the following description of a preferred embodiment thereof, illustrated purely by way of a non-limiting example, in the figures of the accompanying sets of drawings, where:

- Fig. 1 shows in schematic form a top plan view of an apparatus of the type in question relating to the cylinders of a continuous printing machine; - Fig. 2 is a schematic side view of the apparatus according to Figure 1;

- Figs. 3 and 4 show in schematic form a plan view of the further constructional variants for operation of the spraying bars of the apparatus according to the invention;

- Figs. 5, 6 and 7 show possible operating diagrams for the bar electrovalves according to the solution shown in Figure 4;

- Fig. 8 is a top plan view of a constructional variant of one of the supplying bars of the apparatus;

- Figs. 9, 10, 11, 12, 13 and 14 show corresponding details of the bar according to Figure 8 in a side view and views along the cross-sectional lines X-X, Xl-Xl, XII-XII, XIII-XIII, XIV-XIV, respectively;

- Fig. 15 shows other details of the bar according to Figures 8-14, viewed frontally and partly from the side of the nozzles.

From Figures 1 and 2 it can be seen that, according to a non-limiting embodiment (see below), the apparatus 1 comprises spraying bars 8, 18 which are situated transversely on opposite sides of a strip N fed to the successive series of facing cylinders C of a continuous printing machine and is situated upstream of these cylinders, and the nozzles 108 and 118 of the said bars are directed towards the opposite sides of the said strip N, so as to spread over said sides predetermined quantities of solvent which can be varied depending on the feeding speed of the said strip. The bars 8, 18, together with any means consisting, for example, of brushes, spatulas or rollers, which spread on the opposite sides of the strip of paper N the liquid supplied by the said bars (which means are not shown in the drawings), are for example arranged inside housing 2 for containing and collecting the - otherwise dispersed - mist and spray of the liquid supplied by the nozzles of the said bars and for evacuating the collected liquid towards recovery means 3 and this same housing 2 may form or help form the means for recovering immediately the quantity of liquid supplied by the said bars along the flanks of the strip of paper when the latter has a width smaller than the maximum width which can be used by the printing machine and for channelling this liquid by means of gravity towards the said recovery means 3, since the apparatus 1 with the bars 8 and 18 has dimensions widthwise such as to be able to operate on strips of paper N with a maximum width able to be inserted inside the printing machine.

The cleaning liquid supplied onto the opposite sides of the strip of paper N by the spraying bars 8, 18, by means of the said strip N, reaches the printing cylinders C which, during washing, remain operative and which may be provided with their own respective cleaning means P for example of the type consisting of cloth which is pre- impregnated or impregnated with solvent, a brush or other means, and the residual dirt or all of the dirt is transferred to the strip of paper N which removes it, passing in succession through all the pairs of printing cylinders of the machine, and which then passes through the drying oven (not shown).

It is understood that the composition of the apparatus 1 for supplying the cleaning liquid onto the strip of paper, as mentioned with reference to Figures 1 and 2, is purely exemplary and that the improvements in question are applicable to any unit having at least one or both of the said spraying bars 8, 18, with or without the presence of cleaning units P serving the various printing cylinders C (see below). According to the invention, it is envisaged being able to regulate the transverse supply of the liquid supplied by the bars 8 and 18 of the apparatus 1 , depending on the width of the strip of paper N inserted in the printing machine, in order to avoid unnecessary supplying along the flanks of the strip and therefore facilitate the action of the said lateral recovery means 2 according to Figures 1 and 2 and improve the distribution of the cleaning liquid on the said strip of paper, also depending on the amount of dirt spread over the cylinders to be cleaned.

In order to achieve the first of the said objects, the bars 8 and 18 for supplying the liquid of the apparatus 1 (Fig. 3) are each divided into several sections 101 arranged adjacent to each other and each section comprises several nozzles for supplying the liquid and is supplied by at least one line 5 and via several respective intercept electrovalves 29 of the ON-OFF type which control the flow of the liquid supplied from a metering valve 30, for example of the modulated or other suitable type, which is managed by a processing unit 7 having an input 9 which sends a signal proportional to the width of the strip of paper inserted in each case in the printing machine and having a further input 10 for the signal proportional to the feeding speed of the said strip of paper. Depending on the width of the strip of paper used, the apparatus is able to regulate automatically the number of active nozzles of the bars, so as to supply cleaning liquid essentially over the width of the strip, deactivating the sections with the nozzles which would supply liquid along the flanks of the said strip. The variations in the quantity of liquid supplied by the active nozzles of the bars 8, 18 may be achieved in a uniformly distributed manner by means of the metering valve 30. In order to achieve both the objects mentioned above, the solution shown in

Figure 1 may be used, whereby the line 5 supplying the liquid to the various sections 101 of the bars 8 and 18 is intercepted by several respective ON-OFF electrovalves, which are for example at least two in number as indicated by 6, 106 and are controlled by the said processing unit 7 which has an input 9 for modifying the quantity of liquid supplied by each bar section 101 depending on the through-speed of the strip of paper N and which has an input 10 for activating the said sections 101 which act on the width of the strip N which is inserted in each case in the machine, with deactivation of the sections 101 of the bars situated along the flanks of the said strip, so as to avoid unnecessary supplying of cleaning liquid along the flanks of the said strip and so as to facilitate the action of the said lateral recovery means 2. By then operating one and/or the other of the said electrovalves 6, 106 associated with each section 101 of the bars 8 and 18 of the apparatus 1 , it is possible to vary the quantity of liquid supplied by the said active section of the bars.

In the solution according to Figure 1, the processing unit 7 has a further semi- automatically or automatically controlled input 12 which, depending on the distribution of the dirt on the printing cylinders, allows regulation of the quantity of cleaning liquid which is supplied transversely onto the strip of paper by the adjacent sections 101 of the bars 8, 18 of the apparatus 1, so that more solvent reaches the dirtier zones of the cylinders C than the solvent which reaches the cleaner zones. The input command 12 may for example be obtained with a sensor which reads from the ink tank of the machine the quantity of ink used by the said machine and/or by reading with optoelectronic sensors or with telecameras the quantity and the concentration of ink which is present in the matrix of the printing plate and which will be transferred to the rubber during printing. According to a further possibility, the signal to the said input 12 may be provided semi-automatically by an operator who, after a washing cycle, determines which zones of the printing cylinders are dirtier and require a greater quantity of solvent than other zones and transmits the signal to the said input 12 in order to activate the varied supplying of solvent by the active sections 101 of the bars 8 and 18 of the apparatus 1 , which supply the solvent onto the strip of paper. Upstream of the supply line 5, a valve means 11 of the static or dynamic type may be envisaged, said means consisting, for example, of a throttle valve or a modulated electrovalve which if necessary is managed by the processing unit 7 and which, depending on the rated characteristics of the printing machine and the following drying oven, allows safe control of the overall quantity of solvent supplied to the supplying apparatus 1 and released by the latter to the strip of paper. The processing unit 7 and/or the said limiting valve means 11 shall have the task of controlling safe operation of the various electrovalves 6, 106, so as to ensure that, when the supply of the solvent in certain zones of the strip of paper is increased, in other zones of the strip the supply of the said solvent is automatically decreased, so as to keep constant the total quantity solvent sprayed per second by the spraying bars 8 and 18, so that this total quantity corresponds always to the maximum value which can be supplied and is then able to pass through the drying oven safely.

According to a solution equivalent to that illustrated in Figure 1, which allows the use of electrovalves with the same throughput and allows a wider selection of the quantity of solvent supplied by the bars, each section 101 of the said bars 8 and 18 is supplied by the line 5, by means of a respective set of three electrovalves 23, 123, 223 managed by the processing unit 7 which has the usual input 9 for the signal relating to the width of the strip of paper, an input 10 for the signal relating to the feeding speed of the said strip of paper and an input 12 which sends signals relating to the distribution of the dirt on the cylinders to be cleaned and emitted by automatic or semi-automatic sensing systems mentioned above with reference to the solution of Figure 1 , so as to activate the varied supplying of solvent by the various sections of the bars of the apparatus which supply said solvent onto the strip of paper. The overall or selective variations in the quantities of the liquid supplied by the sections 101 of the bars 8, 18 may in this case be managed by the processing unit 7 which operates each set of three electrovalves 23, 123, 223 with constant or different opening times tr and with a step 1, step 2 or step 3 as shown for example in Figures 5, 6 and 7 so that more or less liquid reaches transversely certain zones of the strip depending on the concentration of the dirt on the surface of the series of cylinders to be cleaned.

It is understood that the circuits shown in Figures 1, 3 and 4 are schematic and purely exemplary and that they may be improved with all those solutions which may occur to persons skilled in the art in order to ensure that the cleaning liquid is distributed with the necessary pressure and flowrate to the various sections of the supplying bars and so as to ensure that the system operates under safe conditions, avoiding an excessive supply which could create problems during the following stage of drying of the strip of paper N.

With reference to Figures 8 to 15, a supplying bar for the apparatus 1 , which can be easily produced on an industrial scale and is able to satisfy the abovementioned requirements of safe and varied supplying of the nozzles, is now described. From Figures 8 and 9 and 15 it can be seen that each bar 8 and 18 comprises at least one main longitudinal channel 33 which is closed at one end with a plug 34 and which at the other end is connected to the cleaning liquid supply line, via a union 35 and with the arrangement, in between, of a flowrate regulating valve means 36 - consisting for example of a throttle valve - the characteristics of which may vary depending on the maximum width of the reel of paper which can be inserted in the printing machine, depending on the characteristics of the drying oven and/or any other parameters. These valve means 36 have the function of limiting the maximum quantity of solvent which the bar can supply onto the sheet of paper and which is able to pass through the drying oven safely, without creating the risk of explosion. These same valve means 36 may also be envisaged in the embodiment of the bars 8 and 18 considered above with reference to Figures 1 and 4. Two secondary channels 37 and 38, for example with the same cross-section, are provided parallel to the supply channel 33 at a different distance from the said main channel 33, these secondary channels being closed at the ends with sealing plugs and being divided into sections of equal length, by means of pins 39 (Fig. 14) inserted with sealing means 40 into transverse holes 41 formed in the bar and having a diameter such as to intercept both the said secondary channels 37, 38, these pins being fixed in situ with any suitable means. With these pins 39, the secondary channels 37, 38 are divided, for example, into five portions or sections and each section has a plurality of nozzles 108 or 118, for example ten nozzles, which are alternately connected to each of the said sections of secondary channels 37, 38, as shown in the detail of Figures 12 and 13. Each section of said secondary channels may be connected to the main supply channel 33 by means of pairs of electrovalves for example two pairs of electrovalves 41 , 41' and 42, 42', which have the same flowrate characteristics and are of the ON-OFF type, as shown in the details of Figures 10 and 11. It is clear how, for each section of the secondary channels 37, 38, with the respective nozzles, depending on supplying of the said electrovalves 41, 41' and 42, 42', the cleaning liquid may be supplied in a variable quantity by the nozzles served by the secondary channel section 37 and/or by the nozzles served by the secondary channel section 38. If necessary, the supply to each bar section with its ten nozzles may even be stopped when it is required to supply the cleaning liquid onto strips of paper with a width smaller than the maximum width which can be inserted in the printing machine. In this case, also, as in the case of Figures 1 and 4, the various electrovalves will be managed by a processing unit 7 which has the usual inputs 9, 10 and 12 for the operational adaptation depending on the width of the strip of paper, depending on the feeding speed of the said strip of paper and depending on the distribution of the dirt on the printing machine cylinders to be cleaned. The processing unit 7 according to Figure 8, as well as the processing unit according to Figures 1, 3, 4 and/or the said flowrate limiting valve means 36 will have the task of controlling safe operation of the apparatus so as to ensure that, when the supply of solvent to certain zones of the strip of paper is increased, the supply of the said solvent in other zones of the strip is automatically decreased, so as to keep constant the total quantity of solvent sprayed per second by the spraying bar, so that the total quantity always corresponds to the maximum amount which can be supplied and can then pass safely through the drying oven.

Owing to optimization of the varied supply of the solvent by the nozzles of the various adjacent sections of the bars 101 , it is possible to obtain uniform washing over the entire width of the strip of paper, which condition could not be ensured by a homogeneous and uniformly distributed supply, since the print is never uniformly distributed over the width of the strip of paper. With optimization of the varied supply of the solvent in the transverse direction of the strip of paper, the cleaning times for the zones of the cylinders acted on by the different sections 101 of the bars 8, 18 of the apparatus 1 will tend to be the same, so that the washing times for the various cylinder trains of the printing machine will be shorter than those of the prior art and it will be possible to reduce the overall quantity of solvent used for each washing cycle.

The apparatus as described may be set to perform conventional washing cycles or perform so-called "microwashing" which may be managed by the processing unit 7 via the signal to the input 12 which detects the gradual accumulation of dirt on the different zones of the printing cylinders. With activation of the sections 101 of the spraying bars 8, 18 which are aligned with the zones where there is a gradual accumulation of the dirt on the cylinders, while the printing machine remains in the normal operating condition, it will be possible to supply to the said dirty zones very small quantities of solvent which will soften the said dirt and favour gradual removal thereof during contact with the strip of paper, without adversely affecting the legibility and the quality of the print produced by the machine. Microwashing may otherwise be performed by supplying to the said dirty zones of the cylinders large quantities of solvent in a short amount of time, so as to dissolve the said dirt and favour rapid removal during contact with the strip of paper, the printed sections of which involved in this cycle are then destined for disposal. It is clear how these microwashing operations may increase the time intervals between the main washing cycles and how they may simplify the times and costs of these same main cycles.

Claims

1. Apparatus for cleaning cylinders in continuous printing machines, of the type which operate, for example, upstream of the train of sets of cylinders (C) of a printing machine so as to distribute the cleaning liquid on the advancing strip of paper (N), characterized in that it comprises transversely with respect to the said strip of paper (N) at least one bar or a pair of facing bars (8, 18) with associated nozzles (108, 118) for spraying respectively onto at least one or onto both the opposite sides of the said strip (N) advancing at a suitable speed and in contact with the said cylinders, suitable quantities of a cleaning liquid with solvent, necessary for cleaning the said cylinders and in that has means (2) for immediate recovery of the mist and spray resulting from the action of the said bars and the liquid supplied by the said bar or bars along the flanks of the strip of paper, in particular if it has a width smaller than the maximum width which can be inserted in the printing machine and characterized also in that the said bar or bars (8, 18) are each divided into several sections (101) adjacent to each other, with respective nozzles for supplying the liquid and each section being supplied with cleaning liquid by at least one line (5), with respective electrovalves and with control means which allow modification of the quantity of liquid supplied by the said bar sections (101), depending on the through-speed of the strip of paper (N), and which allow activation of only those bar sections (101) which act on the width of the strip (N) in each case inserted in the printing machine, with deactivation of the sections (101) of the said bar situated along the flanks of the said strip, so as to prevent unnecessary supplying of cleaning liquid and facilitate the action of the said lateral recovery means (2).

2. Apparatus according to Claim 1, in which each section (101) of the said bar or bars (8, 18) is connected to the cleaning liquid supply line (5) by means of respective electrovalves and with control means which allow activation of only those bar sections which act on the width of the strip of paper inserted in the printing machine, which allow modification of the quantity of liquid supplied by all the active bar sections (101) depending on the feeding speed of the said strip of paper and which allow selective modification of the quantity of liquid supplied by each active bar section so that each section sprays onto the advancing strip of paper (N) varied quantities of solvent aligned with the varyingly dirty zones of the printing machine cylinders to be cleaned, so as to supply more solvent to the dirtier zones and less solvent to the less dirty zones of the said cylinders.

3. Apparatus according to Claim 1, in which each section (101) of the said bar or bars (8, 18) is connected to the cleaning liquid supply line (5) via at least one respective electrovalve (29) which controls the flow of the liquid from a main metering valve (30) for example of the modulated or other type, the whole assembly being managed by a processing unit (7) with an input (9) which sends a signal or command proportional to the width of the strip of paper which is in each case inserted in the printing machine and with a further input (10) for the signal or command proportional to the feeding speed of the said strip of paper, all of which so that, depending on the width of the strip of paper used, it is possible to regulate automatically the number of sections (101) with the active nozzles of the bar or bars, so as to supply cleaning liquid over the width of the strip, deactivating the sections with the nozzles which would supply liquid along the flanks of the said strip, while, by operating the said main metering valve (30), it is possible to vary the quantity of liquid which the active sections (101) of the bar or bars (8, 18) supply onto the strip of paper depending on its feeding speed.

4. Apparatus according to Claim 2, in which each section (101) of the said bar or bars (8, 18) is connected to the cleaning liquid supply line (5) by means of at least one pair of electrovalves (6, 106) controlled by a processing unit (7) which has an input (9) for activating the said electrovalves of the bar sections which act on the width of the strip of paper (N) in each case inserted in the printing machine and which has a further input (10) which allows modification of the quantity of liquid supplied by the active sections of the bar or bars depending on the feeding speed of the strip of paper, with the selective or combined operation of the said electrovalves (6, 106) and which has a further input (12) connected to sensing means or means of another suitable type which send signals relating to the distribution of the dirt on the cylinders to be cleaned, so as to allow varied operation of the said active sections of the bar or bars so that the latter spray onto the strip varied quantities of solvent aligned with varyingly dirty zones of the printing machine cylinders to be cleaned.

5. Apparatus according to Claim 2, in which each section (101) of the said bar or bars (8, 18) is connected to the line for cleaning liquid supply line (5) by means respective sets of three electrovalves (23, 123, 223, 23", 123', 223') managed by a processing unit (7) which has an input (9) for the signal relating to the width of the strip of paper, an input (10) for the signal relating to the feeding speed of the said strip of paper and which has a further input (12) connected to sensing means or means of another suitable type, which send signals relating to the distribution of the dirt on the cylinders to be cleaned, all of which so that the said processing unit (7) is able to regulate the distribution of the liquid by the said bar or bars (8, 18) depending on the width of the strip (N), depending on the speed of the said strip and depending on the distribution of the dirt on the cylinders (C) to be cleaned, by operating the said electrovalves with different phases and/or opening times (tr) and with consequent different steps, so that more or less liquid is supplied to certain transverse zones of the strip depending on the need to remove the dirt from the sets of cylinders to be cleaned.

6. Apparatus according to Claim 4, in which the said sensing means which send to the said input (12) of the processing unit (7) signals relating to the distribution of the dirt on the cylinders to be cleaned are, for example, such that they can read from the ink tank the quantity of ink used by the printing machine.

7. Apparatus according to Claim 4, in which the said sensing means which send to the said input (12) of the processing unit (7) signals relating to the distribution of the dirt on the cylinders to be cleaned are, for example, such that they can read the quantity and the concentration of the ink which is present in the matrix of the printing plate and which will be transferred to the rubber during the printing operation and/or sense the said concentration of ink on the strip of printed paper.

8. Apparatus according to Claim 4, in which the said means which send to the said input (12) of the processing unit (7) signals relating to the distribution of the dirt on the cylinders to be cleaned may be of the semi-automatic type and such as to be able to be operated by an operator who, after a washing cycle, assesses directly or indirectly, which zones of the printing cylinders are dirtier and require a quantity of solvent which is greater than in other zones and transmits the signal to the said input (12) so as to activate varied supplying of solvent by the said bar or bars (8, 18) which supply the said solvent onto the strip of paper (N).

9. Apparatus according to Claim 2, characterized in that the circuits supplying the cleaning liquid to the said supply bar or bars (8, 18), when divided into several adjacent sections, have all the means able to ensure that the said cleaning liquid is distributed with the necessary pressure and flowrate to the different sections of the bars and so as to allow the system to operate, also during regulation, with the maximum overall supply of solvent and under safe conditions, preventing an excessive supply which could create problems during the subsequent drying of the strip of paper (N).

10. Apparatus according to Claim 2, in which the supply of the cleaning liquid to the said supplying bar or bars (8, 18) is controlled by a flowrate regulating valve means (11, 36) consisting, for example, of a throttle valve, the characteristics of which may vary depending on the maximum width of the reel of paper which can be inserted in the printing machine, depending on the characteristics of the drying oven and/or any other parameters so that, with the operation of these valve means and/or said processing unit (7) which manages the various electrovalves, it is possible to limit and control the maximum quantity of solvent which each bar is able to supply onto the sheet of paper and which can pass through the drying oven safely, without creating the danger of explosion.

11. Apparatus according to Claim 1 , in which the said bar or bars (8, 18) of the main supply unit (1) comprise at least one main longitudinal channel (33) closed at one end and connected at the other end to the cleaning liquid supply line, and at least two secondary channels (37, 38) are provided parallel to the said main channel (33) at a different distance from the latter, said secondary channels being sealingly closed with suitable means at the opposite ends and being divided into sections of the same length, by means of pins (39) inserted with sealing means (40) in transverse holes (41) formed in the bar, having a diameter such as to intersect both the said secondary channels (37, 38), all of which so that with these pins (39) the said secondary channels (37, 38) are divided into several portions or sections for example of the same length and each having a plurality of nozzles (108, 118) which are alternately connected to one or the other of the said secondary channel sections (37, 38), it being envisaged that each section of the said secondary channels may be connected to the main supply channel (33) by means of pairs of electrovalves, for example two pairs of electrovalves (41 , 41', 42, 42'), having the same or different flowrate characteristics and being of the ON-OFF type, all of which so that, depending on supplying of the said electrovalves (41 , 41' and 42, 42'), the cleaning liquid may be supplied in variable quantities by the nozzles served by each section of a secondary channel (37) and/or by the nozzles served by each section of the other secondary channel (38) and so as to ensure that, if necessary, the supply of each bar section with its ten nozzles may be stopped when it is required to supply the cleaning liquid onto strips of paper with a width less than the maximum width which can be inserted in the printing machine, the said electrovalves being managed by a processing unit (7) having various inputs (9, 10, 12) for operational adaptation depending on the width of the strip of paper, depending on the feeding speed of the said strip of paper and depending on the distribution of the dirt on the printing machine cylinders to be cleaned.

12. Apparatus according to Claim 1 , characterized in that it comprises means which allow it to be used for performing conventional washing cycles or for performing so-called "microwashing" operations which may be managed by the said processing unit (7), via the input signal (12) which detects the gradual accumulation of dirt on the different zones of the printing cylinders, which unit activates the sections (101) of the spraying bar or bars (8, 18) which are aligned with the zones where the dirt gradually accumulates on the cylinders, while the printing machine remains in the normal operating condition, all of which so that it is possible to supply to the said dirty zones very small quantities of solvent which soften the dirt and which favour the gradual removal thereof during contact with the strip of paper, without adversely affecting the quality of the print produced by the machine.

13. Apparatus according to Claim 1 , characterized it that it comprises means which allow it to be used to perform conventional washing cycles or perform intermediate and short washing cycles which may be managed by the said processing unit (7) via the input signal (12) which detects the gradual accumulation of dirt in the different zones of the printing cylinders and which activates the sections (101) of the spraying bar or bars (8, 18) which are aligned with the zones where the dirt gradually accumulates on the cylinders, while the printing machine remains in the normal operating condition, all of which so that it is possible to supply to the said dirty zones large quantities of solvent which dissolve the said dirt and favour the rapid removal thereof during contact with the strip of paper, the printed sections of which involved in this cycle are subsequently destined for disposal.