Ink Thickness Control via Variable Speed Substrate and Inker
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Solution Overview
Problem
Conventional lithographic printing presses waste significant substrate material during the make-ready process due to improper ink film thickness, requiring continuous running and resulting in undesirable waste.
Innovation Solution
A method involving a controller that manages the ink train, plate cylinder, blanket cylinder, and takeaway roller to operate at different surface speeds, allowing the ink train to run at higher speeds than the substrate, and using optical sensors to adjust ink film thickness in a closed-loop system, ensuring optimal optical density without continuous substrate running.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the press runs continuously at the same surface velocity as the inker during make-ready, then the ink transfer process stabilizes and achieves desired ink thickness, but significant substrate material is wasted
Solution Approach 1:
The patent applies dynamics by enabling the inker to operate at variable speeds independent of the substrate. The inker can run at higher speeds during make-ready to stabilize ink transfer without requiring the substrate to run continuously, thus reducing substrate waste while achieving proper ink thickness stabilization
Solution Approach 2:
The patent segments the inker operation from substrate movement by allowing independent control of the inker's surface velocity. This segmentation enables the inker to perform make-ready operations without being constrained by substrate running requirements, separating the ink stabilization function from substrate consumption
2Loss of substance
If the inker runs at higher surface speeds than the substrate during make-ready, then substrate waste is reduced, but the ink transfer process may become unstable
Solution Approach 1:
The patent implements feedback control where optical sensors continuously monitor the ink film thickness on the substrate and provide real-time information to the controller. The controller adjusts the inker's operation based on this feedback to maintain stable ink transfer even when running at variable speeds, ensuring both waste reduction and transfer stability
Solution Approach 2:
The patent replaces mechanical coupling between inker and substrate movement with an optical sensing and electronic control system. Optical sensors detect ink film properties and the controller processes this information to regulate ink delivery, substituting direct mechanical synchronization with an intelligent control loop that maintains stability at variable speeds
3Manufacturing precision
If optical sensors and closed-loop control are used to adjust ink film thickness, then precise ink thickness is maintained, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with an optical sensing and electronic control system. Optical sensors non-contactively measure ink film thickness and the controller electronically adjusts ink delivery, eliminating the need for complex mechanical linkages and manual adjustments while achieving superior precision
Solution Approach 2:
The closed-loop control system is self-regulating, automatically adjusting ink film thickness based on real-time optical feedback without requiring external intervention. The system monitors its own performance and makes corrections autonomously, reducing the need for complex external control mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces substrate waste during start-up and maintains precise ink film thickness, enabling efficient and accurate printing by minimizing the need for continuous substrate running and optimizing ink distribution.
Implementation Method 1
measuring an optical density on the substrate with an optical sensor
Data Source
Figure 1A
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Figure 2
AI summary
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 is 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.