US 2015/0090136 A1 · CLOSED LOOP INK THICKNESS CONTROL SYSTEM WITH REDUCED SUBSTRATE WASTE IN A PRINTING PRESS

Abstract

A method is provided of charging an inker in a lithographic printing press. The method comprises placing all of the printing units of the printing press in an off impression position, with a continuous substrate passing through the printing units, each printing unit including a blanket cylinder; and in one or more printing units of the plurality of printing units, moving the takeaway roller into contact with the blanket cylinder of the printing unit. Thereafter, the method includes driving the ink train, plate cylinder, blanket cylinder and the take away roller at a first surface speed, whereby the ink from the ink train transmitted to the plate cylinder from the ink train, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to the take away roller; and during said driving step, keeping the continuous substrate stationary or moving the continuous substrate at a second surface speed less than 50% of the first surface speed. Also provided is a closed loop control system for controlling the ink film thickness applied to a printed substrate in a lithographic printing press.

Claims14

Dependent claims

A method of charging an inker in a lithographic printing press including a plurality of printing units, each printing unit including a blanket cylinder, a plate cylinder, a take away roller, and an ink train, comprising:

placing all of the printing units of the printing press in an off impression position, with a continuous substrate passing through the printing units, each printing unit including a blanket cylinder;
in one or more printing units of the plurality of printing units, moving the takeaway roller into contact with the blanket cylinder of the printing unit;
and thereafter
driving the ink train, plate cylinder, blanket cylinder and the take away roller at a first surface speed, whereby the ink from the ink train transmitted to the plate cylinder from the ink train, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to the take away roller;
and
during said driving step, keeping the continuous substrate stationary or moving the continuous substrate at a second surface speed less than 50% of the first surface speed.

3 more elements

A method of controlling the ink film thickness applied to a printed substrate in a lithographic printing press including a plurality of printing units, each printing unit including a blanket cylinder, a plate cylinder, a take away roller, and an ink train, comprising:

(a) charging the inker in one or more of the plurality of printing units, said charging including the steps of
placing all of the printing units of the printing press in an off impression position, each printing unit including a blanket cylinder;
in the one or more printing units of the plurality of printing units, moving the takeaway roller into contact with the blanket cylinder of the printing unit;
and thereafter
driving the ink train, plate cylinder, blanket cylinder and the take away roller and thereby transmitting ink from the ink train to the plate cylinder, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to the take away roller;
(b) in the one or more printing units of the plurality of printing units, moving the takeaway roller out of contact with the blanket cylinder of the printing unit
(c) placing the one or more printing units on impression;
(d) printing on the substrate with the one or more printing units as the substrate moves through the printing press;
(e) measuring an optical density on the moving substrate with an optical sensor;
(f) comparing the measured optical density to a predefined metric, and
if the measured optical density is within a predefined metric, continuing to print on the substrate, and
if the measure optical density is outside the predefined metric, repeating steps (a) through (f).

9 more elements

An offset lithographic printing press, comprising:

a plurality of printing units arranged to print images on a web, each printing unit including an ink train, a plate cylinder, a blanket cylinder, a take-away roller, and a further cylinder,
an optical sensor positioned downstream of the printing units, the optical sensor sensing an optical density of a printed web as it passes the optical sensor;
each printing unit including a takeaway roller, the take-away roller being moveable between a first position in contact with the blanket cylinder and a second position spaced away from the blanket cylinder;
each printing unit including a throw off mechanism, the throw off mechanism being configured and arranged to bring the blanket cylinder and the further cylinder together to form a nip in an on-impression position, and to separate the blanket cylinder and the further cylinder in an off impression position;
a controller, the controller connected to each of the printing units and to the optical sensor, the controller configured and arranged to:
(a) control the throw off mechanism in each printing unit to placing all of the printing units of the printing press in the off impression position,
(b) move the takeaway roller in one or more of the printing units into the first position;
and thereafter
(c) drive the ink train, plate cylinder, blanket cylinder, further cylinder and the take away roller and thereby transmit ink from the ink train to the plate cylinder, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to the take away roller;
(d) move the takeaway roller in one or more of the printing units into the second position;
(e) control the throw off mechanism in the one or more printing units to place the one or more printing units in the on impression position;
(f) drive the ink train, plate cylinder, blanket cylinder, and further cylinder and thereby transmit ink from the ink train to the plate cylinder, from the plate cylinder to the blanket cylinder, and from the blanket cylinder to a moving substrate;
(g) measure an optical density on the moving substrate from the optical sensor;
(h) comparing the measured optical density to a predefined metric, and
if the measured optical density is within a predefined metric, continuing to print on the substrate, and
if the measure optical density is outside the predefined metric, repeating steps (a) through (h).

13 more elements

Dependencies are inferred from the claim text.

Closed loop ink thickness control system with reduced substrate waste in a printing press

Life of this patent

Closed loop ink thickness control system with reduced substrate waste in a printing press

Life of this patent

Abstract

Claims14