Alternating wet cleaning and dry cleaning of a flexographic printing plate

Abstract

An apparatus comprises a plate cleaner assembly. The plate cleaner assembly further comprises a frame, a roller coupled to the frame, a dry cleaning material coupled to the roller, and a spray assembly coupled to the plate cleaner assembly. The plate cleaner assembly further includes a controller coupled thereto. Moreover, the apparatus further comprises a printing plate cylinder and a printing plate coupled to the printing plate cylinder.

Claims

1. An apparatus, comprising: a plate cleaner assembly, wherein the plate cleaner assembly further comprises: a frame; a roller coupled to the frame; a dry cleaning material coupled to the roller such that the dry cleaning material passes over the roller, and a spray assembly coupled to the plate cleaner assembly; a controller coupled to the plate cleaner assembly; a printing plate cylinder, and a printing plate coupled to the printing plate cylinder wherein the controller is configured to: determine a width of a spray pattern by the spray assembly; determine an amount of time to move the dry cleaning material; determine an amount of time to elapse between a wet cleaning and a dry cleaning; determining a number of cleaning cycles; determine a pressure for a nozzle of the spray assembly to spray solvent; and determine a pressure for the roller to apply to the printing plate.

2. The apparatus of claim 1, further comprising a plurality of motors coupled to the frame.

3. The apparatus of claim 2, wherein the plurality of motors comprises: a linear actuator motor; a material rewind motor; and an impression motor.

4. The apparatus of claim 1, further comprising: a first spindle, the first spindle containing an amount of the dry cleaning material; and a second spindle, the second spindle to pull the dry cleaning material from the first spindle such that the dry cleaning material passes over the roller.

5. The apparatus of claim 1, wherein the plate cleaner assembly moves along an axis parallel to the printing plate cylinder and printing plate by a linear actuator motor.

6. The apparatus of claim 1, wherein the roller moves perpendicular to the printing plate by an impression motor.

7. The apparatus of claim 1, wherein the spray assembly further comprises: a solvent supply; and a nozzle coupled to the solvent supply, wherein the nozzle draws solvent from the solvent supply.

8. The apparatus of claim 1, wherein the spray assembly moves laterally with respect to the printing plate.

9. The apparatus of claim 2, wherein the controller is further configured to regulate the movement of each motor of the plurality of motors.

10. A plate cleaner apparatus for cleaning a print plate coupled to a printing plate cylinder, the plate cleaner apparatus comprising: a plate cleaner assembly, wherein the plate cleaner assembly further comprises: a frame, a roller coupled to the frame, a dry cleaning material coupled to the roller such that the dry cleaning material passes over the roller, and a spray assembly coupled to the plate cleaner assembly; and a controller coupled to the plate cleaner assembly, wherein the controller is configured to: determine a width of a spray pattern by the spray assembly; determine an amount of time to move the dry cleaning material; determine an amount of a printing plate to be cleaned; determine an amount of time to elapse between a wet cleaning and a dry cleaning; determining a number of cleaning cycles; determine a pressure for a nozzle of the spray assembly to spray solvent; and determine a pressure for the roller to apply to the printing plate.

11. The apparatus of claim 10, further comprising a plurality of motors coupled to the frame.

12. The apparatus of claim 11, wherein the controller is further configured to regulate the movement of each motor of the plurality of motors.

13. The apparatus of claim 11, wherein the plurality of motors comprises: a linear actuator motor; a material rewind motor; and an impression motor.

14. The apparatus of claim 10, further comprising: a first spindle, the first spindle containing an amount of the dry cleaning material; and a second spindle, the second spindle to pull the dry cleaning material from the first spindle such that the dry cleaning material passes over the roller.

15. The apparatus of claim 10, wherein the plate cleaner assembly moves along an axis parallel to the printing plate cylinder and printing plate by a linear actuator motor.

16. The apparatus of claim 10, wherein the roller moves perpendicular to the printing plate by an impression motor.

17. The apparatus of claim 10, wherein the spray assembly further comprises: a solvent supply; and a nozzle coupled to the solvent supply, wherein the nozzle draws solvent from the solvent supply.

18. The apparatus of claim 10, wherein the spray assembly moves laterally with respect to the printing plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side elevational view of a cleaning head using the wetting subassembly of the present invention with spray nozzle on and the dry cleaning apparatus and assembly in a clear position where it is not engaged with the printing plate in accordance with the present disclosure.

(2) FIG. 2 is a side elevational view similar to FIG. 1 but showing the spray nozzle off and the dry cleaning apparatus and assembly engaged with the wetted printing plate in a cleaning position to absorb water or other solvent using the dry cleaning material as it passes over the printing plate.

(3) FIG. 3 is a representative schematic illustrating a travel path for the cleaning apparatus relative to a print cylinder and plate disposed on the print cylinder.

DETAILED DESCRIPTION

(4) Referring now to the drawing views in detail, wherein like numbered elements refer to like elements throughout the drawings, FIGS. 1 and 2 illustrate a preferred and representative embodiment of a printing plate cleaner structure (or plate cleaner), generally identified 10, of a dry cleaning apparatus and assembly that is fabricated in accordance with the present invention.

(5) As shown, the plate cleaner 10 comprises a frame having multiple motorsa linear actuator motor, a cloth rewind motor, and an impression, or tilt, motor. It is to be understood that such motors may be one motor or any combination of motors, from a group consisting of electric motors, hydraulic motors, pneumatic motors, and the like, the type of motor(s) used not being a limitation of the present invention.

(6) The frame of the plate cleaner 10 also comprises a roller 20 and dry cleaning material 22 that passes over the roller 20. During normal use, the plate cleaner 10 moves laterally and along the surface of a printing plate 62 that is secured to a print cylinder 60. That is, the roller 20 has an axis that is parallel to that of the printing plate cylinder 60. The roller 20 is also that structure of the plate cleaner 10 over which a portion of dry cleaning material 22 is pulled, the dry cleaning material 22 being fed from a web of such material that is disposed within the plate cleaner 10. It is also within the scope of the present invention to provide a version of the plate cleaner 10 having a roller 20 that adjusts its impression using an eccentric cam on its roller shaft (not shown). This version allows for a smaller footprint and provides more versatility to the functionality of the plate cleaner 10.

(7) In the preferred embodiment, the plate cleaner 10 comprises an unwind spindle (not shown) that carries the web of unsoiled dry cleaning material, such as a woven or non-woven polyester, or any other absorbent cloth or cloth-like material. Another spindle (also not shown) is a rewind spindle that pulls the web of dry cleaning material from the unwind spindle about a portion an outer surface of the roller 20 and back to the rewind spindle. At the point of return to the rewind spindle, the dry cleaning material 22 is soiled with printing debris and ink, as described above.

(8) However, it is to be understood that the exact placement of the rewind and unwind spindles relative to the assembly of the present invention is not a limitation of the present invention. That is, different configurations of the spindles are available depending on the specific application and use to which the plate cleaner 10 of the present invention is desired or required. However, the functionality of the pulling of the dry cleaning material 22 from an unwind spindle across a portion of the roller 20 and back to a rewind spindle is required regardless of placement of those structures within the plate cleaner 10. It is also intended that the axes of the roller 20 and the spindles be parallel with the axis of the print plate cylinder 60, although the spindles could be used with other structures to accomplish feeding or take-up of the unsoiled or soiled dry cleaning material, respectively.

(9) A linear actuator motor provides a means for moving the plate cleaner 10 longitudinally along a track system (not shown) that is also parallel to the axis of the print plate cylinder 60. An impression, or tilt, motor allows the roller 20 of the plate cleaner 10 to move toward and away from the surface of a printing plate 62 that is attached to the print cylinder 60. This last structure is significant in that it provides functionality such that relatively tight or precise control of the pressure that the plate cleaner roller 20 places on the printing plate 62 as the printing plate 62 and the print cylinder 60 rotate is attained. This allows the cleaning roller 20 and the material 22 (also referred to herein as a web) to be moved closer to or further from the surface of the printing plate 62 for optimized spacing and cleaning of that surface, thereby placing more or less pressure on the printing plate. This also allows the operator to make position and pressure adjustments between the plate cleaner and the print plate without the need to stop the printing press or the printing process.

(10) Referring specifically to FIG. 1, it shows a spray subassembly 30 that is attached to the plate cleaner 10. The spray subassembly 30 comprises a nozzle 32 which draws solvent from a supply (not shown) and deposits a spray pattern of solvent 34 onto the plate 62. During the depositing of the water 34 onto the plate 62, the plate cleaner 10 is moving laterally along the plate 62. FIG. 2, however, shows the ceasing of spray from the nozzle 32 and engagement of the roller 20, as well as the web 22 passing over the roller 20, such that the web 22 absorbs the solvent and removes wetted debris from the plate 62.

(11) In application, the solvent may be sprayed directly onto the web 22 by the nozzle 32. Once the web 22 has been wetted, the roller 20 may pass over the plate 62, allowing the wetted web 22 to wipe the plate 62. In some examples, the roller 20 may be oscillated with respect to the plate 62. Said differently, the roller 20 may be moved while passing the wetted web 22 over plate 62. This may result in a scrubbing action by the roller 20 and therefore, by the wetted web 22. In such examples, the roller 20 may oscillate in alternating movement by forward and backwards directions. The roller 20 may pass over the plate 62 in a pattern similar to the pattern shown in FIG. 3.

(12) As alluded to above, the present invention further provides an electronic controller (not shown) that utilizes a controller network interface and an electronic control unit to monitor and control the cleaner, either directly or in accordance with a pre-programmed scheme. The electronic controller uses programmable instructions to determine operational parameters and institute electronic commands to the electronic control unit in a pre-determined response operational framework. When the controller is enabled, it monitors certain operational parameters of the plate cleaner 10 and the wetting subassembly 30. In the controller of the present invention, the operational parameters are configurable, allowing the setup to be optimized for a particular method of operation, regardless of the specific application that the plate cleaner is used for, and is programmable to make adjustments accordingly.

(13) Continuing, and when traversing across the plate 62, the head 10 should advance at a rate of one spray-pattern width per print cylinder revolution. An exemplary programmable feature, such as Number of Wipes to slow down the head 10 in the event that more water is needed, can be included. During this first pass, the head 10 should stay at the clear position. Once wetting of the plate 62 is complete, the head 10 should return to its starting point to begin the cleaning process. It is desirable to add the ability to preset a dwell time between the wetting and cleaning cycle.

(14) On the second pass, the plate cleaner 10 will traverse the printing plate 62 with the head 20 and web 22 at the cleaning position. An independent pressure setting for the cleaning may be programmed if the pressure applied needs to be greater or lesser than the standard pressure for normal cleaning. Once again, the head 20 should dwell for one revolution at the beginning and end of travel so that the entire plate 62 is cleaned. Preferably, the head 20 should advance across the plate 62 at a rate of 100 millimeters per revolution of the print cycle. Another programmable feature, such as Number of Wipes, can be added to slow down the head 20 in case that is needed. It may be necessary to repeat the wetting and cleaning pass cycle multiple times to get the plate 62 to its desired level of cleanliness.

(15) Before beginning the cleaning pass, it is also preferred to advance the web 22 a distance so that it is not starting the wet clean with an already soiled cloth. Likewise at the end of the cleaning pass, it is preferred to advance the web 22 so that the plate cleaner 10 does not start its normal cleaning cycle with a dirty wet cloth, as this could adversely impact print quality. It may also be desirable to advance the web 22 faster during the wet cleaning cycle.

(16) It would be preferred that the spray nozzle 32 work at standard water pressures so that the subassembly 30 can be plumbed into the press water supply lines, as opposed to requiring a separate tank that must be regularly filled and maintained.

(17) In accordance with the preferred embodiment, the controller of the present invention also comprises a number of automated and enhanced cleaning functionalities that may be included with the base apparatus, system, and method of the present invention. Each functionality is intended to interface with the electronic controller of the present invention to enhance overall operation and optimization of the apparatus, system, and method of the present invention. In accordance with the foregoing, programmable inputs from the processor may include:

(18) Press Speed; and

(19) Print Unit Ready Signal.

(20) Programmable inputs on a wet clean setup screen may include:

(21) Spray pattern width (measured at setup);

(22) Cloth advance time before starting clean;

(23) Cloth advance time after finishing clean; and

(24) Repeat diameter (from system setup screen.

(25) Programmable inputs on a wet clean operator screen may include:

(26) Number of Wipes for water spraying;

(27) Number of Wipes for cleaning;

(28) Cleaning width (from EditKleen screen);

(29) Pressure setting;

(30) Dwell time between wetting and cleaning;

(31) Number of cleaning cycles; and

(32) Cloth speed.

(33) Further, outputs may include water valve solenoid per section.

(34) In accordance with the foregoing, an apparatus, assembly, and method is provided for initiating a printing plate wetting of a flexographic printing plate, followed by dry cleaning of the plate, as needed during a production run. The apparatus, assembly, and method is provided such that the plate wetting and dry cleaning process can also be used to clean the printing plate prior to storage of the plate for future use. Further, such an apparatus, assembly, and method can be easily removed from the printing press for service and maintenance when necessary.