Heidelberger Druckmaschinen Ag

Neil Doherty

Kevin Lauren Cote

Lothar John Schroeder

Lawrence Edward Zagar

Kent Dirksen Kasper

David Robert Dawley

Stephen Arthur Austin

Michael Roger Perreault

A method for determining the presence of slipping of a driven nip roller relative to the web in a web printing press includes systematically changing the speed of the nip driver while monitoring the corresponding change in web tension difference across the nip. The linearity and a slope of the relationship between the tension difference and the speed of the nip driver are determined. When the tension difference is non-linear relative to the speed of the driver or the slope of the relationship is substantially less than an expected slope, then slipping is determined to be present. An operator slip indication may be provided which includes the direction of the slip, positive or negative. The operator may then take corrective action to re-establish a non-slip condition, or automatic corrective actions may ensue.

Method and apparatus for determining slipping in a nip roller

A method for controlling a chill roll system in a web printing press includes calculating, based on a web inlet temperature of a web entering a first chill roll of the chill roll system, a dew point temperature of an ink solvent vapor of ink printed on the web is calculated. The inlet coolant temperature of coolant entering the first chill roll is set to temperature value near the calculated dew point temperature. Using a heat transfer model, the flow rate of the coolant through the first chill roll needed to maintain a temperature rise of the coolant through the first chill roll below a predetermined value is determined. The method prevents post-chill marking by sufficiently cooling the web, and sets chill roll temperature profiles to avoid solvent condensation on chill roll surfaces and thereby avoid condensate marking.

Method for controlling a chill roll system

A method for dynamically controlling a driver of a nip roller in a web printing press includes controlling the speed of the driver in a tension-control mode during a phase of printing press operation and in a velocity-control mode during another phase of printing press operation. The controlling of the speed of the driver in the tension-control mode is based on the tension in the web upstream of the nip roller so as to maintain the tension at a desired tension value. The controlling of the speed of the driver in the velocity-control mode is based on a predetermined driver velocity ratio for maintaining the web tension. The tension-control mode may be employed during press start-up as the web accelerates to operating speed. The velocity-control mode may be used during printing operations of the press.

Method and apparatus for dynamically controlling a web printing press

An inker of an offset printing press is preset in accordance with the image coverage distribution for an image to be printed. The image coverage distribution is obtained from a plate scanner or from a digital image setter file that is available during makeready. Whether in simulation or in actual print, the printed ink film commands are first set. Then inking operation is simulated and a simulated ink coverage distribution is obtained by driving a steady state error between the printed ink film commands and the ink coverage to zero. The presets are calculated in a proportional-integral controller with feedback from a simulated printing plant. The resulting ink key presets are then used to preset the ink keys of the inker at the start of the actual print job.

Ink key presetting system for offset printing machines

An air bar for steering a web of material has a hollow interior subjected to an air bar supply pressure. At least one air jet exit is connected to the hollow interior of the air bar. A metering device is assigned to the hollow interior of the air bar for varying the air pressured formed below the web of material for moving the web of material in a lateral direction.

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Durham, NH, United States of America

Neil Doherty