Wash-up system for flexographic printers

Abstract

A wash-up system for cleaning a flexographic printing system of the type including a pair of ink supply rollers, an ink reservoir, a gravity feed tank for the ink, and a pump in the reservoir for pumping ink to the gravity tank from where the ink flows to the ink rollers. The wash-up system includes suitable apparatus for draining the residual printing ink from the printing system into the ink reservoir, pumping the ink from the reservoir into an ink recovery vessel, directing wash water under pressure to portions of the printing system for cleaning the system, draining the wash water from the printing system into the ink reservoir and then draining the wash water from the reservoir. The apparatus basically comprises a water supply line that branches to various parts of the printing system with appropriate automatically operated solenoid valves for directing the water to portions of the printing system during various controlled phases of the wash-up cycle.

Description

BACKGROUND OF THE INVENTION

1. Field of the Intention

This invention relates generally to printing and more particularly to processes and cleaning attachments for cleaning portions of a flexographic printing system.

2. Description of the Prior Art

Flexographic printing systems generally include an etched or engraved ink transfer roll carrying ink in the pockets of the engravings which is transferred to a rubber die mounted on a rotating print cylinder. The ink is transferred from the die to the matter to be printed. To assure a fine film of ink on the ink transfer roll, either a scraper blade or a doctor roll is maintained in contact with the supply roll during operation. Customarily ink is supplied to the nip between the supply roll and doctor roll from a supply line located near the center of the length of the rolls. The ink flows along the nip to both ends of the rolls where it falls into an ink trough. Ink from the trough is usually drained into a reservoir for the ink. The reservoir includes a pump which pumps the ink from the reservoir back to the supply line to the nip between the rolls. To assure a constant flow of ink to the nip of the rolls, a gravity feed tank may be located above the rolls. Ink from the reservoir is pumped to this tank from where it is supplied by gravity through the supply line to the nip of the rolls.

Flexographic ink is a water-based ink. This ink must be removed from the printing system when a change in color is made to print a different color on another run of material such as box blanks. When a color change is required, it is also necessary to clean all portions of the printing system so that no residual ink of the first color is mixed with the second color to be printed. Such printing systems are usually manually cleaned by an operator who merely pours water into the ink trough, into the nip of the rolls, into the ink reservoir, and into the gravity feed tank. He then scrubs the surfaces of these portions of the printing system with a cloth to remove the ink therefrom.

This procedure is time consuming and may also waste water since the amount of water used depends upon the preferences of the operator.

Accordingly, an object of the present invention is to provide a fully automatic system for cleaning the various portions of the printing system in a minimum amount of time and with very little operator attention. Another object is to conserve the amount of water needed to clean the printing system.

SUMMARY OF THE INVENTION

In accordance with this invention, the printing function of the system is stopped, the residual printing ink is drained from the system into the ink reservoir, the ink is drained from the reservoir to an ink recovery vessel, wash water is directed under pressure to portions of the printing system and under gravity to other portions of the system for cleaning the system, the wash water is drained from the system into the reservoir, and the wash water is then drained from the reservoir to any convenient disposal system such as a plant sewage system. At the time the wash water is being supplied to the printing system, the ink supply rollers are rotated to expose their surfaces to the wash water.

Suitable apparatus for performing the foregoing steps includes a supply of water under pressure which is directed to a nip between the ink rollers, to the ink reservoir, and to a gravity feed tank for the ink. The apparatus also includes automatically operated valves which direct the wash water to various portions of the printing system at different times during the wash cycle. A timer is used to control the time that wash water is applied to and drained from various portions of the system. Advantageously, high intensity spray nozzles are used at various locations in order to provide a high intensity water spray to the hardest to clean areas of the system.

The above and further objects and novel features of the invention will appear more fully from the following detailed description when considered in connection with the accompanying drawings; however, the drawings are not intended as a definition of the invention but are for illustration only.

DESCRIPTION OF THE DRAWINGS

In the drawings wherein like parts are marked alike:

FIG. 1 is a diagramatic illustration of a typical flexographic printing system showing the wash-up system of the invention applied thereto;

FIG. 2 illustrates a control panel used to control the wash-up system; and

FIG. 3 is a timing diagram illustrating the sequence of operation of the wash-up system.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, the printing system generally denoted by numeral 10 includes an ink supply roll 12 of the conventional type which is suitably journaled in bearings (not shown) and driven by gears (not shown) or by an electric motor 13. Ink in the engravings in roll 12 is transferred to a rubber die 14 which is suitably attached to a print cylinder 16 located adjacent the supply roll 12. A rubber covered doctor roller 18 is located adjacent to supply roll 12 in a manner which permits it to be rotated against the roll 12. Conventional gears (not shown) mounted in meshing engagement on the ends of rollers 12 and 18 drive the doctor roll 18 from roll 12. This arrangement forms a nip 20 between the rollers 12 and 18. Printing ink 24 is supplied to nip 20 from the center of the rolls towards each end where it falls into an ink trough 26. The ink in trough 26 is drained into a reservoir 28 by means of a drain line 30.

The reservoir 28 includes a conventional ink pump 32 which is capable of pumping the ink 24 to the nip 20 through supply line 22. However, it is preferable to pump the ink 24 to a gravity tank 34 by means of a supply line 36A and 36B. The supply line 22 is connected to the bottom of gravity tank 34 so that the ink flows by gravity through line 22 to nip 20.

The purpose of using the gravity feed tank 34 is to assure a constant supply of ink to the nip 20 of rolls 12 and 18. Should the ink supply fail, the rubber roll may be damaged since it is customarily held against the surface of the supply roll 12 at a slight pressure. There is usually a slight difference between the surface speed of the supply roll 12 and rubber roll 18 to provide a wiping action to assure an even, thin film of ink on the surface of the supply roll 12. If no ink is present, the engraved surface of the roll 12 may damage the rubber covering on roll 18 by abrasion.

It can be seen in FIG. 1 that the supply line 22 is connected to the bottom of the tank 34. However, the upper level of ink in tank 34 is controlled by an excess ink drain line 38 connected to a higher overflow level 39 of the tank 34 and to the reservoir 28.

The gravity feed tank 34 usually includes a sensor 35 such as shown and described in application serial number 144,469 filed on May 18, 1971 by Gordon L. Morgret, now abandoned, and assigned to the assignee of the present invention.

The sensor 35 extends into gravity tank 34 so that its lower tip is between the bottom of the tank and the overlfow level 39. If the level of ink falls below the tip, an electrical circuit is interrupted to extinguish a lamp (not shown) to warn the operator. This signals the operator to add more ink to reservoir 28 if the supply is low or to open a conventional needle valve 31 in line 36A from pump 32 to increase the flow of ink through the system or to otherwise look for some malfunction of the ink supply system.

In the event that no ink is being supplied to nip 20, the rolls 12 and 18 will become dry. This creates an overload condition caused by dry friction between the rolls. A conventional electrical overload sensing circuit 13A connected to drive motor 13 senses the additional current needed by motor 13 to drive rolls 12 and 18. The sensing circuit can be used to supply an electrical signal to stop operation of motor 13 or, if desired, may be connected to a fluid-actuated pivot arrangement to move the surface of roll 18 away from roll 12 by a slight amount. The pivot arrangement may include mounting the journals 15 of roll 18 in a pivot lever 17 (only one shown) which is pivotally mounted in the machine side frames (omitted for clarity). A pneumatic cylinder 19 may be actuated by the signal from the sensing circuit to move roll 18 away from roll 12. If desired, journals 15 may be mounted in conventional eccentric housings which may be rotated by pneumatic cylinder 19 or an equivalent rotary air cylinder.

The gravity feed tank 34 may also include a cylindrical filter 40 through which the ink must pass from feed line 36B to get into the tank 34. This filter traps any paper dust or other foreign matter in the ink so that clean ink is supplied to the nip 20 of rolls 12 and 18.

The wash-up system for the printing system 10 generally includes a main water supply 50 from which a branch line 52 runs to the ink supply rolls 12 and 18; a branch line 54 running to the ink reservoir 28; and a branch line 56 running to the gravity tank 34. Line 52 is divided at juncture 156 from which another line 58 runs to an edge of the trough 26 and extends substantially parallel thereto. Line 58 includes a plurality of conventional high intensity spray nozzles 60 which direct water under line pressure against the surfaces of rolls 12 and 18 and into the trough 26 thereby washing ink from the rolls and the trough 26. The nozzles may be of the type designated 8686 by Spraying Systems Co., Bellwood, Ill. Different spray patterns are available to provide the coverage needed.

Another line 62 runs from juncture 156 to juncture 64 which divides the line 62 into a pair of substantially identical lines 66 and 68 which extend to the ends of the nip 20. A high intensity spray nozzle 60 on the end of each of lines 66 and 68 directs water towards the ends of the rolls 12 and 18 where the ink from nip 20 flows downward into trough 26.

The water in tank 34 drains through line 22 to the center of the nip 20 thereby supplying a flow of water (similar to the flow of ink) which runs along the nip and overflows from the ends of rolls 12 and 18 into the trough 26. As the water in tank 34 reaches level 39 in tank 34, it drains through line 38 into the reservoir 28 thereby cleaning ink from the line.

Line 54 is divided at juncture 172 into two lines 174 and 76. Lines 174 and 76 are arranged to extend along the inside of reservoir 28 and include a plurality of high intensity spray nozzles 60 which sprays water inside the reservoir to remove any ink from the sides and bottom thereof.

Lines 36A and 36B are joined by a conventional electro-pneumatic solenoid valve 78. This valve includes a drain line 80 so that when it is in one operating position, water or ink will flow from line 36A through valve 78 to line 36B and to tank 40 or in the other operating position, ink or water will be prevented from flowing into line 36B and will flow into drain line 80.

Valve 28 may be, for example, a size 200B full port ball valve made by Contromatics Corp., Rockville, Conn. Such valves are operated by energizing an electric solenoid in a separate conventional air flow control valve (not shown) which supplies air under pressure to switch valve 78 in the desired direction to either supply ink or wash water to gravity tank 34 or permit ink or wash water to drain through line 80.

Reservoir 28 also includes a drain line 82 connected to another similar electro-pneumatic solenoid valve 84 (conveniently mounted on the side of reservoir 28) which, when operated, permits ink or water to be drained fron tank 28 through drain line 86 from valve 84.

From the foregoing, it can be seen that water is directed to all parts of the printing system through the ink lines such as to the supply rolls 12 and 18, the ink trough 26, the gravity tank 34, and the ink reservoir 28. Water flows from the tank 34 by gravity to the nip 20 under gravity pressure similar to the manner in which ink is supplied to the nip 20. Water also flows by gravity through excess drain line 38. However, water flowing to other parts of the system is sprayed under line pressure to clean the ink from the various parts of the system. It should be noted that water is caused to flow through all of the lines that normally supply the ink to the system and drain ink from the system. Thus, all of the lines are cleaned as well as the other parts of the system.

In operation, it will first be assumed that the system is clean and that ink is to be supplied to the supply rolls 12 and 18. Ink reservoir 28 is filled with ink of the desired color in the usual manner. The ink pump 32 is turned on which pumps ink from reservoir 28 through line 36A, through valve 78 and into line 36B and into the bottom of gravity tank 34. The ink flows through filter 40 and into the tank. As the ink starts to fill tank 34, it will flow through supply line 22 into the nip 20 between the rolls 12 and 18. The ink 24 flows along nip 20 and overflows from the ends of the rolls 12 and 18 and into ink trough 26. The ink trough 26 is conveniently sloped to the left as viewed in FIG. 1 so that the ink flows into drain 30 and into the reservoir 28. Thus the ink that is not used in printing is returned to the reservoir where it is again pumped through the system by pump 32 thereby assuring a continuous supply of ink to the nip 20 between rolls 12 and 18. It should be noted that as the ink in gravity tank 34 reaches level 39, the excess ink drains through line 38 and back into the reservoir 28. It should also be noted that the roll 18 is urged against roll 12 by pneumatic cylinder 19 and the rolls 18 and 12 are rotated only after the ink begins circulating through the system so that the rolls do not run dry against each other. Preferably, rolls 12 and 18 are not engaged and rotated until the print cylinder 16 is rotated to begin the printing operation. An interlock (not shown) may be used if desired to prevent rotation of the rolls 12 and 18 if the ink is not circulating through the system or the rolls may be rotated out of engagement by suitably energizing air cylinder 19 as previously explained.

Assuming now that the printing run has been completed and a new color is to be used on the next printing run, the first step is to remove the ink from reservoir 28. The valve 78 is switched so that, as the ink pump 32 is operated, ink will be drawn from the reservoir 28 and directed out of the system through drain line 80. The ink from line 80 may flow into an ink bucket (not shown), or, if preferred, be directed through an extension of the line to a remote ink storage area. As the ink pump 32 pumps the ink out of the system through line 80, the residual ink will continue to drain from the system, that is, from the nip 20 into trough 26 and from there back to reservoir 28. The ink in the bottom of gravity tank 34 will also drain through line 36B, through valve 78, and into line 80 from where it flows to the ink bucket.

The next step is to supply water to the printing system 10 to clean all of the various parts thereof. Line 50 includes a conventional pressure regulator valve 88 which is manually turned to provide water under line pressure of about 40 pounds per square inch (40 P.S.I.) to the main lines 52, 54 and 56. Water under line pressure in line 52 flows to line 58 and through high intensity spray nozzles 60 to clean the rolls 12 and 18 and ink trough 26. The water also flows under pressure through line 62 and lines 68 and from spray nozzles 60 to clean the ends of the rolls 12 and 18.

Simultaneously, water is supplied to the gravity tank 34 through line 56. The high intensity spray of water through nozzle 60 cleans the inside of tank 34; the water in tank 34 flows through line 22 into the nip of the rolls and along the length of the rolls where it overflows the ends of the rolls and falls into trough 26 and thereafter drains through line 30 to the reservoir 28. It should be noted that the filter 40 is preferably removed from gravity tank 34 and manually cleaned outside the system.

Water is also supplied under line pressure through line 54 to lines 74 and 76 inside the reservoir 78. The water is sprayed through nozzles 60 to clean the inside of reservoir 28. As the water builds up in reservoir 28, the solenoid valve 84 is switched so that the water drains from the reservoir 28 through exhaust or drain line 86 to a sump or other disposal system (not shown).

From the foregoing, it can be seen that water is supplied to all parts of the printing system 10. The water flows through all the lines that normally carry ink in the printing system thereby cleaning these lines and the water is also sprayed under pressure through the spray nozzles 60 to various parts of the system such as the gravity feed tank 34, the rollers 12 and 18, the ink trough 26, and inside the reservoir 28 to flush all of the ink that may cling to the various surfaces of these parts. During at least part of the wash cycle, water is pumped from reservoir 28 to gravity tank 34 thereby cleaning the ink pump also.

As previously mentioned, it is an object of this invention to conserve the amount of water needed to clean the printing system. It has been found that it is not necessary to supply wash water to all parts of the system simultaneously in order to achieve the desired cleanliness of the system. Thus, the system is arranged so that wash water is supplied to the highest point of the system first, i.e., gravity tank 34, so that water from that point drains through the system and into the ink reservoir 28 before wash water is supplied to other parts of the system. The exact arrangement can be seen by reference to FIG. 3 which is a timing diagram illustrating the sequence that wash water is supplied to the various portions of the printing system and the length of time that it is supplied as will be subsequently explained.

Because of various operating conditions it is not always necessary to follow all of the steps needed for a complete cleaning procedure. The system is arranged to provide three wash cycles: a "complete wash" cycle; a "long rinse" cycle; and a "short rinse" cycle. The complete wash cycle is most often used when a color change in the ink is to be made or at the end of an order. The long rinse cycle is usually used after a manual wash-up of the printing system and the short rinse cycle is used as needed to remove paper dust or other foreign matter from the ink supply system.

The desired cycle is initiated at the control panel 60 shown in FIG. 2. The control panel includes a selector lever 62 with a dial indicator 64, a start push-button 66, an excess ink push-button 68, an open/close drain push-button 70 and an open drain indicator light 72.

The cycle selector lever 62 is connected directly to a conventional cam operated limit switch assembly which is connected directly behind the control panel 60 (switch assembly not shown). The switch assembly or sequence timer may be one such as a type C10 made by the Raymond Controls Corp., Middleton, Conn. The switch assembly includes a cam shaft 74 to which the selector lever is connected. A small electric drive motor is connected to the other end of the cam shaft. The cam shaft carries a ganged series of circular cams between the selector lever and the drive motor one of which is illustrated in dotted lines and denoted by numeral 63. The annular surface of each cam is formed to provide at least one high area 65 and one low area 67. A conventional limit switch 69 is located adjacent each cam. Thus, as the cam shaft 74 is rotated by the drive motor, the cams are all caused to rotate; as they do so, the high areas on the cams will close the adjacent limit switch and conversely the low areas permit the limit switches to open.

Wires from the limit switch 69 carry electric signals to various parts of the wash-up system such as ink pump 32 and solenoid valves 78 and 84. Thus, it can be seen that these devices may be turned on and left on for whatever period of time is desired as determined by the shape of the cam controlling its associated limit switch.

A conventional electrically operated flow valve 70 is placed in line or conduit 52 between water supply 50 and the spray nozzles 60 in conduit 58 and spray nozzles 60 in conduits 66 and 68. Valve 70 is controlled by a signal from the limit switch associated with the cam illustrated by the horizontal bar in FIG. 3 denoted "supply rolls spray"; when the limit switch is energized by the high surface of the cam, it supplies a signal to an electric solenoid in valve 70 which opens the valve and permits water to flow therethrough. When the signal stops, the valve closes to prevent water from flowing through conduit 52. Thus the water pressure control valve 88 may be left open to provide water at the desired pressure to conduit 52. A similar valve 72 is placed in conduit 54 between water supply 50 and the spray nozzles 60 in conduits 74 and 76. Valve 72 is controlled by a signal from the limit switch associated with the cam illustrated by the bar denoted "reservoir spray" in FIG. 3 in the same manner as explained for valve 70. Thus, the flow of water from water supply 50 is selectively controlled to the conduits 74 and 76 in reservoir 28.

Similarly, a valve 74 is placed in conduit 56 to control the flow of water from supply 50 to spray nozzle 60 in gravity tank 34; valve 74 is controlled by the limit switch associated with the cam illustrated by the bar denoted "gravity tank spray" in FIG. 3 in the same manner as previously explained for valves 70 and 72. If desired, nozzle 60 may be omitted from the end of conduit 56 and the water permitted to flow unrestricted into tank 34.

Flow control valves 70, 72 and 74 may be a two-way normally closed general purpose valve, Part No. LC2DB4150 made by Skinner Electric Valve Div. of Skinner Precision Industries, Inc., New Britain, Conn.

The desired sequence of operation of the wash-up system is provided by the sequence timer whose operation is fully illustrated by the timing diagram of FIG. 3. In FIG. 3, each horizontal bar represents one of the cams that controls the device indicated for the bar. The length of the bar represents one revolution of the cam.

It has been found that a period of 71/2 minutes is sufficient to completely clean the ink supply system for a color change. Therefore, the cam shaft is rotated by its motor once in 71/2 minutes thereby rotating each cam once in the same period of time. The shaded portion of the horizontal bars represents the condition of the device being controlled as indicated by the indicia at the left end of each bar. A cam is also included to stop the cam shaft drive motor at the completion of the cycle thereby resetting the assembly for the next cycle. A time scale at the bottom of the diagram illustrates the actual time desired for operation of each device controlled by a cam.

To accomplish a complete wash cycle the following procedure is followed: the ink pump 32 is turned on, the rubber roll 18 is engaged with the supply roll 12 by extending air cylinder 19 by an appropriate control (not shown) and, the printing system is stopped. A bucket is placed under the discharge pipe 80 and the excess ink button 68 is pushed on the control panel 60; button 68 is held on to discharge ink from line 80 until a 5 gallon indicator 11 is visible inside the reservoir 28. Button 68 is then released and the ink bucket is removed and another empty 5 gallon bucket is placed under pipe 80.

The purpose of the 5 gallon indicator is that ink is normally supplied in 5 gallon buckets which are emptied into reservoir 28 which preferably has a capacity of 10 gallons. Assuming only 2 gallons are used for printing before a color change is made, the operator may drain 3 gallons from the system into an empty bucket, that is, until the ink level reaches the 5 gallon indicator 11 in reservoir 28; at that time he may remove the partially filled bucket and replace it with an empty bucket which can then be filled with the 5 gallons of ink remaining in the reservoir by leaving button 68 depressed. Thus, the operator is freed for other tasks.

Then with the selector lever 62 turned to the "start" position on dial 64; the start button 66 is pushed to initiate the complete washing cycle. The cams are rotated by the camshaft drive motor thereby opening and closing the limit switches to control operations of the ink pump 32, solenoid valves 78 and 84, etc. in accordance with the sequence shown in FIG. 3. A green indicator light 66A in the center of push-button 66 indicates that an automatic wash is in progress; the green light is connected to the reset cam limit switch so that it is turned off when the cycle is completed. The filter 40 is also removed from the gravity tank 34 and either completely cleaned or replaced with a clean filter before the wash cycle is begun.

To accomplish a long rinse cycle, the first 21/2 minutes of the complete wash cycle are by-passed by turning the selector lever 62 to the beginning of the "long rinse" indicated on dial 64 of panel 60. Turning lever 62 actually rotates the cams past the limit switches so that when the cycle is initiated by the start button 66, the cams begin to rotate at their advanced positions. Thus, to accomplish a long rinse cycle the following procedure is followed: with no ink in the ink supply system, the printing system is stopped with the supply roll 12 and rubber roll 18 rotating in engagement and the ink pump 32 is turned on. The selector lever 62 is rotated clockwise to the beginning of the long rinse cycle indicated on dial 64 and the start button 66 is pushed to initiate the rinse cycle. As previously indicated, the rinse is complete when the green light goes off. Again the filter 40 is either cleaned or replaced.

A short rinse cycle is similarly accomplished by turning the selector 62 clockwise to the beginning of the "short rinse" indicated on dial 64. The cams are rotated as before to an advanced position thereby by-passing approximately the first 41/2 minutes of the complete wash cycle. To accomplish a short rinse, the following procedure is followed: with no ink in the ink supply system, the printing system is stopped with the rubber roll 18 engaged with the supply roll 12 with both running and the ink pump 32 is turned on. The selector 62 is rotated to the beginning of the short rinse cycle indicated in the dial. The start button 66 is pushed. The filter 40 is removed and emptied of collected materials and then replaced in the gravity tank 34. After the rinse is completed, ink is added to reservoir 28 for beginning the next order.

It should be recognized that printing systems such as illustrated in FIG. 1 may be operated in tandem relationship with the blanks being printed advancing as indicated by the arrow on the blank B illustrated in phantom lines in FIG. 1. Each system may apply a different color ink to the blank or only one color may be applied while the other printing system is being cleaned by the wash-up system of this invention. Accordingly, the invention affords a further advantage in that production need not be stopped while cleaning is in progress on the printing system not being used.

It has been found that more efficient cleaning occurs if the temperature of the wash water is approximately 140.degree.F or more. Thus, the supply line 50 may be connected to a hot water supply usually available in the printing environment.

It has also been found that cleaning may be enhanced by the addition of detergents to the cleaning system. Thus, following drainage of the residual ink from the system as previously explained, any suitable powder or liquid detergent may be manually or automatically added to the wash water, preferably by manually adding it to the reservoir 28. The detergent will be flushed from the system during final spraying of the wash cycle and will drain with the wash water from drain line 86.

From the foregoing, it can be seen that the cleaning system permits maximum recovery of the residual ink from the printing system, conserves the amount of water needed to clean the system, and frees the operator for other tasks while cleaning is in progress. More thorough cleaning is possible since the cleaning steps are reliably repeated each time the system is used.

Accordingly, the invention having been described in its best embodiment and mode of operation, that which is desired to be claimed by Letters Patent is:

Claims

We claim:

1. A method of cleaning a flexographic printing system comprising the steps of:

a. stopping the printing function of said printing system;

b. draining residual printing ink from said system including:

draining ink from a gravity tank in said system to an ink reservoir beneath said gravity tank; and draining ink from a trough beneath an ink roller in said system to said reservoir;

c. pumping ink drained into said reservoir therefrom into an ink storage container for removal from said system;

d. spraying wash water into said gravity tank and thereafter, spraying wash water onto said ink roller and draining the same into said trough;

e. draining said water from said gravity tank and said trough into said reservoir; and

f. draining said wash water from said reservoir to outside of said system.

2. The method of claim 1 and the additional step of:

simultaneously spraying wash water into and draining said reservoir prior to spraying wash water into said gravity tank.

3. The method of claim 1 and in addition:

rotating said ink supply roller in said printing system during the time that said wash water is directed to said ink roller.

4. Apparatus for cleaning a flexographic printing system having at least one ink roller comprising:

a trough beneath said ink roller for collecting excess ink and for collecting wash water from said ink roller;

a gravity tank higher than said roller for supplying ink and for supplying wash water to said ink roller;

a reservoir lower than said trough for collecting excess ink and collecting wash water from said trough;

pump means in said reservoir for pumping ink into said gravity tank and pumping residual ink therein into a storage container for said ink;

water supply means for supplying wash water to said printing system;

first conduit means connected between said water supply means and said gravity tank for directing said wash water into said gravity tank;

second conduit means connected between said water supply means and said ink roller for directing said wash water onto said ink roller after said wash water has been directed into said gravity tank; and

drain means in said reservoir for draining wash water from said reservoir to outside of said system.

5. The apparatus of claim 4 and, in addition:

third conduit means connected to said water supply means for directing said wash water into said reservoir prior to wash water being directed into said gravity tank.

6. The apparatus of claim 5 further including:

first conduit valve means in said second conduit means for controlling the flow of said wash water from said water supply means to said ink roller;

second conduit valve means in said first conduit means for controlling the flow of said wash water from said water supply means to said gravity tank; and

third conduit valve means in said third conduit means for controlling the flow of said wash water from said water supply means to said reservoir.

7. The apparatus of claim 6 further including:

timing means for controlling operation of said pump means, and said first, second, and third valve means' for first pumping said ink from said system and thereafter for selectively draining residual ink from said reservoir, spraying said wash water at high intensity onto said ink roller and into said gravity tank and said reservoir, and draining said wash water from said reservoir to outside said system.

8. The apparatus of claim 7 wherein said timing means includes selectively operable selector means for controlling said pump means, and said first, second, and third conduit valve means to pump, spray, and drain said wash water in a preselected sequence.