Offset Printing Dampening Unit Roller Mixing
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Solution Overview
Problem
Conventional offset printing press dampening units face issues with ink and water not being fully kneaded or emulsified, leading to uneven printing and potential stains, especially when the image area factor increases, due to the use of a single roller for ink supply and incomplete mixing in the ink and water paths.
Innovation Solution
The introduction of a dampening unit with a dampening water communication path comprising a first oscillating roller, a second oscillating roller, and a bridging roller, which allows for selective communication between the inking and dampening units, ensuring that ink and water are fully kneaded and distributed together on the printing plate, with the bridging roller enabling controlled mixing and emulsification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ink accepting roller is used to supply ink to the dampening roller, then the device complexity is reduced, but ink and water are not fully kneaded and emulsified leading to uneven printing
Solution Approach 1:
The ink supply path is segmented into multiple rollers (first ink oscillating roller, second ink oscillating roller, ink distributing roller) that work in sequence to progressively knead and distribute ink with dampening water, replacing the single roller system and achieving full emulsification
Solution Approach 2:
The ink distributing roller acts as an intermediary between the ink oscillating rollers and the dampening roller, receiving ink from one oscillating roller and transferring it to the dampening roller while mixing with dampening water to achieve proper emulsification
2Productivity
If the ink accepting roller is brought into contact with the dampening roller to furnish both water and ink, then the productivity is improved for large image area prints, but excessive emulsification occurs causing printing stains
Solution Approach 1:
The system dynamically adjusts the contact configuration between rollers based on printing requirements. The bridging roller can be positioned to connect or disconnect the ink supply path, allowing flexible control over the emulsification process to match different image area factors and prevent excessive emulsification
Solution Approach 2:
The multi-roller configuration provides controlled feedback mechanisms where each roller's rotation and contact pressure can be adjusted to optimize the mixing ratio of ink and dampening water, preventing over-emulsification while maintaining high productivity
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 solution ensures that ink and water are thoroughly mixed and emulsified, preventing excessive emulsification and printing stains, while maintaining uniform distribution across the printing plate, regardless of the image area factor.
Implementation Method 1
ink and water are fully kneaded or distributed together when the apparatus is brought into communication with the inking unit
Implementation Method 2
a dampening roller in rotational contact therewith and adapted to furnish the printing plate with dampening water alone or together with ink
Data Source
Figure 1
Figure 2
AI summary
In an offset printing press a dampening water communication path 17 which brings an inking unit 4 and a dampening unit 5 in and out of communication so that they can come in and out of contact with each other. The dampening water communication path comprises a plurality of rollers including an oscillating roller 14 in rotational contact with an ink distributing roller 8 and an oscillating roller 16 in rotational contact with a dampening roller 10, and a roller interposed between them is a bridging roller 15 in rotational contact with one of these adjoining rollers and capable of coming in and out of contact with the other.