Porous roll with axial zones and method of proving printing liquid to a cylinder in a printing press

1. A roll for distributing printing liquid in a printing press comprising:

a roll core having at least a first axial zone and a second axial zone;

a first liquid feed for feeding liquid to the first axial zone;

a second liquid feed for feeding the liquid to the second axial zone independent of the first axial zone;

a porous shell covering the first and second axial zones;

at least one first liquid distributing component in the first axial zone between an outer surface of the roll core and an inner surface of the porous shell; and

at least one second liquid distributing component in the second axial zone between the outer surface of the roll core and the inner surface of the porous shell.

2. The roll recited in claim 1 further comprising a seal preventing the liquid from flowing between the first and second axial zones.

3. The roll recited in claim 1 wherein the first liquid feed includes a first interior tube feeding liquid to the first axial zone from inside of the roll core and the second liquid feed includes a second interior tube feeding to the second axial zone from inside of the roll core.

4. The roll recited in claim 3 further comprising a first liquid pump pumping liquid through the first interior tube to the first axial zone and a second liquid pump pumping liquid through the second interior tube to the second axial zone.

5. The roll recited in claim 1 further comprising a bearing allowing the porous shell to rotate around a center axis of the roll core.

6. The roll recited in claim 1 wherein the at least one first liquid distributing component includes at least one first check valve regulating the flow of liquid between the roll core and the porous shell in the first axial zone and the at least one second liquid distributing component includes at least one second check valve regulating the flow of liquid between the roll core and the porous shell in the second axial zone.

7. The roll recited in claim 6 wherein the at least one first liquid distributing component includes a first channel extending circumferentially along the inner surface of the porous shell, the liquid flowing from the roll core through the at least one first check valve to the first channel, the at least one second liquid distributing component includes a second channel extending circumferentially along the inner surface of the porous shell, the liquid flowing from the roll core through the at least one second check valve to the second channel.

8. The roll recited in claim 1 wherein the at least one first liquid distributing component includes at least one first distribution tube providing the liquid from the roll core to the porous shell in the first axial zone and the at least one second liquid distributing component includes at least one second distribution tube providing the liquid from the roll core to the porous shell in the second axial zone.

9. The roll core recited in claim 8 wherein each of the at least one first distribution tube and the at least one second distribution tube takes a diagonal path towards the roll core as the at least one first distribution tube and the at least one second distribution tube provide the liquid from the roll core to the porous shell.

10. The roll recited in claim 9 wherein the at least one first liquid distributing component includes a first channel extending circumferentially along the inner surface of the porous shell, the liquid flowing from the roll core through the at least one first distribution tube to the first channel, the at least one second liquid distributing component includes a second channel extending circumferentially along the inner surface of the porous shell, the liquid flowing from the roll core through the at least one second distribution tube to the second channel.

11. The roll core recited in claim 10 wherein the at least one first distribution tube includes a first radially extending portion connecting a portion of the at least one first distribution tube taking the diagonal path to the first channel such that printing liquid entering the at least one first distribution tube from the roll core flows radially inward toward the roll core in the portion of the at least one first distribution tube taking the diagonal path and then flows radially outward toward the porous shell in the first radially extending portion, the at least one second distribution tube includes a second radially extending portion connecting a portion of the at least one second distribution tube taking the diagonal path to the first channel such that printing liquid entering the at least one second distribution tube from the roll core flows radially inward toward the roll core in the portion of the at least one second distribution tube taking the diagonal path and then flows radially outward toward the porous shell in the second radially extending portion.

12. The roll recited in claim 8 wherein each of the at least one first distribution tube and the at least one second distribution tube provides the liquid from the roll core to the porous shell by following a path that prevents the liquid from flowing to the porous shell solely because of centrifugal forces caused by rotation of the roll.

13. The roll recited in claim 12 further comprising at least one liquid pump pumping liquid from the roll core to the porous shell and providing a positive pressure to the at least one first distribution tube and the at least one second distribution tube, the positive pressure causing liquid to flow through the at least one first distribution tube and the at least one second distribution tube to the porous shell.

14. The roll recited in claim 1 wherein the liquid is ink.

15. The roll recited in claim 1 wherein the liquid is dampening fluid.