Method for reducing register errors on a web of material moving through the printing nip of a multicolor web-fed rotary press and corresponding devices

A method for reducing register errors on a web of material passing through a printing gap of a multi-color, web-fed rotary printing press including:

• providing a bendable roller;
• looping said web of material around said bendable roller in a direction of web travel at a loop angle;
• and
• establishing a curvature of said bendable roller as a function of a register error occurring in said running direction of said web of material.

A multi-color web-fed rotary printing press comprising:

• at least first and second printing groups, each defining a printing gap and arranged to print at least first and second colors on a web passing through said at least first and second printing groups;
• at least one bendable roller positioned at an inlet to at least one of said printing groups, said at least one bendable roller being looped by said web;
• and
• at least one actuating member usable to set a curvature of said at least one bendable roller and wherein said curvature of said at least one bendable roller is set as a function of a register error in a running direction of said web.

A multi-color, web-fed rotary printing press comprising:

• at least first and second printing groups, each defining a printing gap and being arranged to print at least first and second colors on a web passing through said first and second printing groups;
• at least one web deforming device having a plurality of deformation elements and being adapted to deform said web in a direction perpendicular to a running direction of said web to reduce register error, at least first and second of said deformation elements being arranged to act at said edge of said web and a third of said deformation elements being arranged to act between said first and second deformation elements;
• means for adjusting a position of each of said deformation elements relative to each other and perpendicularly to a running direction of said web;
• at least one actuating member for setting a position of at least one of said deformation elements and wherein said deformation elements are set as a function of a register error in a running direction of said web.