Method and printing unit for influencing lateral web spreading in particular in rotary presses
View Patent ↗A printing unit for influencing lateral web spreading in particular in rotary presses, which makes constant contact conditions possible across the width in the rubber-rubber nip and improves the lateral-register quality and the web run without using concave or convex blanket cylinders, has a blanket cylinder and plate cylinders which can be set against the former for printing on one or both sides of a web. The web passes through between the blanket cylinders in a contact zone, it either being possible to skew at least one of the blanket cylinders with respect to the respective plate cylinder or it being possible to skew at least one of the plate cylinders with respect to the respective blanket cylinder, for producing a concave velocity profile on the web.
1. A printing unit for influencing lateral web spreading in a rotary printing press, the printing unit comprising:
first and second transfer cylinders contacting each other along a contact zone and arranged for receiving a web to be printed on therebetween,
at least one plate cylinder respectively settable onto one of said first and second transfer cylinders for printing on at least one side of the web receivable between said first and second transfer cylinders in the contact zone, and
at least one rubber blanket clamped onto one of said first and second transfer cylinders,
wherein said one of said first and second transfer cylinders is movable to a skewed position relative to the at least one plate cylinder so that a pressure in a center region of the contact zone along a length of the contact zone is increased, thereby increasing the effective radius of the at least one rubber blanket from the center region of the contact zone outward so that a concave velocity profile is producible on the web receivable in the contact zone between said first and second transfer cylinders, the velocity at the outer sides of the concave velocity profile being greater than the velocity at the center of the velocity profile.
2. The printing unit of claim 1 , wherein said first and second transfer cylinders are skewed so that longitudinal axis thereof traverse one another.
3. The printing unit of claim 1 , further comprising a motorized adjusting unit for adjusting the skewed position of said one of said first and second transfer cylinders.
4. The printing unit of claim 1 , further comprising at least one of rubber-blanket sleeves and rubber blankets arranged on each of circumferential surfaces of said first and second transfer cylinders.
5. The printing unit of claim 1 , further comprising first and second plate cylinders settable on said first and second transfer cylinders, and at least one of printing-form sleeves and printing plates arranged on each of circumferential surfaces of said first and second plate cylinders.
6. The printing unit of claim 1 , wherein one of said first and second transfer cylinders is configured as an impression cylinder.
7. A printing unit for influencing lateral web spreading in a rotary printing press, the printing unit comprising:
first and second transfer cylinders contacting each other along in a contact zone and arranged for receiving a web to be printed on therebetween,
at least one plate cylinder respectively settable onto one of said first and second transfer cylinders for printing on at least one side of the web receivable between said first and second transfer cylinders in the contact zone, and
at least one rubber blanket clamped onto one of said first and second transfer cylinders,
wherein said at least one plate cylinder is skewable with respect to the respective one of said first and second transfer cylinders so that a pressure in a center region of the contact zone along a length of the contact zone is increased, thereby increasing the effective radius of the at least one rubber blanket from the center region of the contact zone outward so that a concave velocity profile is producible on the web receivable in the contact zone between said first and second transfer cylinders, the velocity at the outer sides of the concave velocity profile being greater than the velocity at the center of the velocity profile.
8. The printing unit of claim 7 , wherein said first and second transfer cylinders are skewed so that the longitudinal axes thereof traverse one another.
9. The printing unit of claim 7 , further comprising a motorized adjusting unit for adjusting the skewed position of said at least one plate cylinder.
10. The printing unit of claim 7 , further comprising at least one of rubber-blanket sleeves and rubber blankets arranged on each of circumferential surfaces of said first and second transfer cylinders.
11. The printing unit of claim 7 , wherein said at least one plate cylinder includes first and second plate cylinders respectively settable onto said first and second transfer cylinders, said printing unit further comprising at least one of printing-form sleeves and printing plates arranged on each of circumferential surfaces of said first and second plate cylinders.
12. The printing unit of claim 7 , wherein one of said first and second transfer cylinders is configured as an impression cylinder.