Anilox Cleaning Method for Ghosting Reduction
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Solution Overview
Problem
Anilox printing units face issues with ink profile persistence leading to ghosting effects during job changes, resulting in increased start-up waste and spoiled prints due to the small axial oscillation amplitudes of distributor rollers, which complicates ink removal from the inking unit back into the ink fountain.
Innovation Solution
A method involving two process steps: first, over inking by engaging all inking unit rollers to evenly distribute ink, and second, removing ink by engaging the bridge roller with the ink applicator and screen rollers to scrape off residual ink without using cleaning agents, ensuring a homogeneous starting condition and preventing ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the ink is removed from the inking unit by scraping the ink back into the ink fountain, then the ink profile in the depressions of the screen roller is reduced, but the ink profile persists in the form of different fill levels of the depressions of the screen roller, leading to follow-up ghosting
Solution Approach 1:
The patent applies preliminary action by performing a pre-flush operation before the actual ink removal. A flush roller is used to apply a flush solution to the screen roller and ink applicator roller, dissolving and loosening the ink profile in the depressions before the doctor blade scrapes it back into the ink fountain. This preliminary chemical action ensures that the ink is fully removed without leaving residual fill levels that would cause ghosting.
Solution Approach 2:
The patent introduces an intermediary substance - the flush solution - that mediates between the ink profile and the doctor blade. The flush solution acts as a chemical intermediary that dissolves the ink in the screen roller depressions, making it easier to remove completely. This intermediary approach allows for thorough ink removal without the mechanical limitations of direct scraping, eliminating the ghosting problem.
2Reliability
If the amplitudes of the axial oscillation of the distributor rollers in the inking units are comparatively small, then the tendency to ghosting is reduced during the print run, but the ink removal from the inking unit back into the ink fountain becomes complicated
Solution Approach 1:
The patent replaces the mechanical ink removal system with a chemical solution approach. Instead of relying on the mechanical action of the doctor blade to scrape ink from the screen roller depressions (which is complicated by small oscillation amplitudes), the system uses a flush solution to chemically dissolve the ink. This substitution of mechanical action with chemical action simplifies the ink removal process while maintaining the benefit of small oscillation amplitudes during printing.
Solution Approach 2:
The patent changes the parameter of ink removal mechanism from mechanical scraping to chemical dissolution. By introducing the flush solution, the ink profile is transformed from a solidified residue requiring mechanical removal to a dissolved state that is easily flushed away. This parameter change in the removal mechanism resolves the contradiction between maintaining small oscillation amplitudes during printing and enabling easy ink removal.
3Productivity
If the doctor blade is engaged with the screen roller and the ink applicator roller is engaged with the screen roller but not with the forme cylinder, then the ink is scraped back into the blade-type ink fountain, but the ink profile in the depressions of the screen roller persists
Solution Approach 1:
The patent applies preliminary action by performing a pre-flush operation before the actual ink removal. A flush roller is used to apply a flush solution to the screen roller and ink applicator roller, dissolving and loosening the ink profile in the depressions before the doctor blade scrapes it back into the ink fountain. This preliminary chemical action ensures that the ink is fully removed without leaving residual fill levels that would cause ghosting.
Solution Approach 2:
The patent introduces an intermediary substance - the flush solution - that mediates between the ink profile and the doctor blade. The flush solution acts as a chemical intermediary that dissolves the ink in the screen roller depressions, making it easier to remove completely. This intermediary approach allows for thorough ink removal without the mechanical limitations of direct scraping, eliminating the ghosting problem.
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
The method effectively reduces ghosting by achieving a homogeneous ink distribution and removal, minimizing start-up waste and ensuring accurate printing by eliminating residual ink profiles on rollers.
Implementation Method 1
the ink is removed from the screen roller and returned into the same ink fountain while the ink applicator roller is in contact with the screen roller and with the bridge roller
Implementation Method 2
the ink applicator roller is in contact with the screen roller
Data Source
AI summary
A method for cleaning an anilox printing unit includes a first process step and a second process step immediately following the first process step without any intermediate printing operation. In the first process step, printing ink is supplied to a screen roller from a blade-type ink fountain while an ink applicator roller is in contact with the screen roller and out of contact with a bridge roller of a dampening unit. In the second process step, printing ink is removed from the screen roller and returned into the same blade-type ink fountain while the ink applicator roller is engaged with the screen roller and with the bridge roller.