Plate cylinder with larger diameter central image area
A plate cylinder has a cylinder body, a first image area at one end of the cylinder body, the first image area having a first average diameter, a second image area at the other end of the cylinder body having a second average diameter, and a third image area between the first and second image areas. The third image area has a third average diameter larger than the first and second average diameters. A print unit, web offset printing press and a plate bender are also provided.
1 . A plate cylinder comprising:
a cylinder body;
a first image area at one end of the cylinder body, the first image area having a first average diameter;
a second image area at the other end of the cylinder body having a second average diameter; and
a third image area between the first and second image areas, the third image area having a third average diameter, the third average diameter being larger than the first and second average diameters.
2 . The plate cylinder as recited in claim 1 wherein the first and second average diameters are the same.
3 . The plate cylinder as recited in claim 1 wherein the first image area, second image area, and third image area each carry two side-by-side images.
4 . The plate cylinder as recited in claim 1 further comprising a first printing plate for attachment in the first image area, a second printing plate for attachment in the second image area, and a third printing plate for attachment in the third image area.
5 . The plate cylinder as recited in claim 4 further comprising a fourth printing plate for attachment in the third image area.
6 . The plate cylinder as recited in claim 5 further comprising a fifth printing plate for attachment in the first image area.
7 . The plate cylinder as recited in claim 1 wherein the first image area has a single image in the circumferential direction.
8 . The plate cylinder as recited in claim 1 wherein the first area has a constant diameter equal to the first average diameter over an axial extent of the first image area.
9 . The plate cylinder as recited in claim 8 wherein the third image area has a further constant diameter equal to the third average diameter over an axial extent of the third image area.
10 . The plate cylinder as recited in claim 1 wherein the first image area is crowned.
11 . The plate cylinder as recited in claim 1 wherein the third image area is crowned.
12 . The plate cylinder as recited in claim 1 wherein the first, second, and third image areas are crowned.
13 . The plate cylinder as recited in claim 1 wherein the third image area includes a first conically-shaped section.
14 . The plate cylinder as recited in claim 13 wherein the third image area includes a second conically-shaped section opposed to the first conically-shaped section so as to define a largest diameter of the plate cylinder.
15 . The plate cylinder as recited in claim 1 wherein the cylinder body has a larger diameter middle section larger than a diameter of either the one end or the other end of the cylinder body.
16 . The plate cylinder as recited in claim 1 further comprising packing around the cylinder body at the third image area, and at least one printing plate placed over the packing.
17 . The plate cylinder as recited in claim 4 wherein the third printing plate is thicker than the first and second printing plates.
18 . An offset print unit comprising the plate cylinder as recited in claim 1 and a blanket cylinder with a compressible blanket contacting the plate cylinder.
19 . An offset web printing press comprising a web, a plate cylinder as recited in claim 1 and a blanket cylinder with a compressible blanket contacting the plate cylinder and the web.
20 . A plate bender for a printing plate for use on the plate cylinder of claim 1 , the plate bender comprising:
a processor receiving information on an intended axial position of the printing plate on the plate cylinder; and
a movable section for altering the effective post-bending length of the plate as a function of the intended axial position of the plate.
21 . A plate bender for a printing plate comprising:
a base for supporting the plate; and
a movable section skewable with respect to the base.