Recirculating Bath Cleaning for Variable Data Lithography
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Solution Overview
Problem
Current lithographic printing systems are not capable of high-speed variable printing as they require replacing print cylinders and imaging plates for each impression, limiting their efficiency in accommodating changing images, and existing cleaning systems face challenges in speed and cleaning efficiency, especially with ink coverage.
Innovation Solution
A variable data lithographic cleaning apparatus utilizing a first cleaning member with medium surface energy and a second cleaning member with high surface energy, along with an ink flushing device using a melamine sponge, to efficiently transfer and remove ink residue from a conformable blanket surface, ensuring effective cleaning regardless of speed and ink coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional imaging plate with permanently patterned image is used, then long print runs of the same image are achieved, but variable printing capability is lost
Solution Approach 1:
The imaging plate surface is made dynamically reconfigurable through a conformable coating layer that can be repeatedly imaged and cleaned. This allows the same physical plate to adapt to different image patterns for variable printing while maintaining productivity through continuous operation without plate replacement.
Solution Approach 2:
Instead of discarding the entire imaging plate after one print run, the system recovers and reuses the plate by cleaning off residual ink and applying new fountain solution patterns. The conformable coating is discarded and replenished periodically, allowing continuous variable printing capability.
2Reliability
If cleaning systems use traditional methods, then ink residue is removed, but cleaning efficiency and speed are limited
Solution Approach 1:
The cleaning system replaces traditional mechanical scraping with a chemical-facilitated transfer mechanism. Fountain solution is applied to the imaging plate, and a conformable coating transfers ink residue to a cleaning member through surface energy differential, eliminating the need for high-speed mechanical scraping while maintaining cleaning effectiveness.
Solution Approach 2:
The system changes the surface energy parameters of the cleaning members to optimize ink transfer. The conformable coating has higher surface energy than the imaging plate, creating a thermodynamic driving force for ink residue transfer. This parameter optimization enables efficient cleaning at higher speeds without sacrificing reliability.
3Productivity
If high-speed variable printing is implemented, then printing speed and flexibility are improved, but cleaning efficiency becomes insufficient
Solution Approach 1:
The system performs preliminary cleaning action by applying fountain solution to the imaging plate before the conformable coating contact. This pre-wetting facilitates faster and more complete ink residue transfer during the brief contact time at high printing speeds, maintaining cleaning efficiency despite reduced interaction time.
Solution Approach 2:
The conformable coating acts as an intermediary medium that facilitates ink residue transfer from the imaging plate to the cleaning member. This intermediary enables efficient transfer at high speeds by providing a large contact area and optimized surface energy characteristics, bridging the gap between high-speed printing and effective cleaning.
4Reliability
If scraping methods are used to clean the conformable surface, then ink residue is removed, but the conformable surface is damaged
Solution Approach 1:
The system replaces mechanical scraping with a chemical-facilitated transfer process. Fountain solution softens and mobilizes ink residue, and surface energy differential drives transfer to the conformable coating, eliminating mechanical contact that would damage the conformable surface while maintaining cleaning effectiveness.
Solution Approach 2:
The conformable coating serves as an intermediary that receives ink residue through non-mechanical transfer. This intermediary protects the underlying imaging plate structure by absorbing the cleaning action, preventing direct mechanical contact and surface damage while maintaining cleaning reliability.
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 system achieves exceptional cleaning efficiency by transferring ink residue from a lower to a higher surface energy surface, allowing for high-speed variable data lithographic printing without scraping the conformable surface, thereby maintaining print quality and reducing maintenance costs.
Implementation Method 1
a first cleaning member having a surface layer with a durometer at most 45 shore A, a surface roughness Ra less than 20 micro inches and a surface energy of 29-35 dynes/cm... to transfer residual ink from the imaging member to the surface layer of the first cleaning member
Implementation Method 2
a second cleaning member having a hard surface with a surface roughness Ra less than 10 micro inches and a surface energy at least 8 dyne/cm higher than the surface energy of the first cleaning member... to transfer the residual ink from the first cleaning member to the second cleaning member
Implementation Method 3
an ink flushing device having a melamine sponge disposed in a liquid bath of cleaning solution against the hard surface of the second cleaning member to remove the residual ink from the second cleaning member to the cleaning solution
Implementation Method 4
the sponge conforming against the second cleaning member and wiping the residual ink from the rotating second cleaning member against the sponge while lubricating the surface of the second cleaning member with the cleaning
Data Source
AI summary
A variable lithographic cleaning apparatus, system and method works on the principle that dust and ink residue may be transferred from a lower surface energy reimageable conformable blanket surface to a higher surface energy surface low durometer cleaning member, such as the tacky roller, and then to an even higher surface energy cleaning member, such as the hard roller, which is hard and robust to scratching. The hard roller can then been scrubbed clean by an ink flushing device having a third cleaning member, such as a melamine sponge, wetted with a cleaning solution with the hard roller dried upon each rotation.