Coating Device with High-Speed Media Stream Sealing
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Solution Overview
Problem
Existing coating devices struggle to achieve uniform coating of moving webs at varying speeds while preventing air inclusions in the coating medium, especially at higher production speeds.
Innovation Solution
A coating device featuring a transfer roller with depressions for the coating medium, a counter roller, and a high-speed media stream from a nozzle that seals the gap between the transfer roller and the main chamber, preventing air entry and ensuring consistent coating weight across a range of application weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher pre-chamber pressure is used to prevent air entry at higher speeds, then air inclusion is prevented, but minimum application weight increases
Solution Approach 1:
The system is divided into two separate chambers: a first chamber for receiving coating medium and a second chamber for applying it to the web. This segmentation allows independent pressure control in each chamber, enabling the first chamber to maintain higher pressure for air prevention while the second chamber operates at lower pressure for precise coating weight control.
Solution Approach 2:
A transfer roller acts as an intermediary between the two chambers. It receives coating medium from the first chamber and transfers it to the web in the second chamber, allowing the coating medium to be applied without direct pressure transmission from the first chamber to the second chamber, thus decoupling the pressure requirements.
2Reliability
If higher pre-chamber pressure is used to prevent air entry, then air bubbles are prevented, but coating uniformity deteriorates
Solution Approach 1:
By segmenting the coating system into two separate chambers with independent pressure control, the invention allows the first chamber to maintain higher pressure for air bubble prevention while the second chamber maintains lower pressure for uniform coating application, eliminating the trade-off between air prevention and coating uniformity.
Solution Approach 2:
The transfer roller serves as an intermediary that receives coating medium at higher pressure from the first chamber and delivers it to the web at controlled pressure in the second chamber, preventing air bubbles while maintaining coating uniformity through the intermediate transfer mechanism.
3Device complexity
If open ink pans and fountain rollers are used, then device complexity is reduced, but productivity decreases
Solution Approach 1:
The invention merges the advantages of simpler open ink pan structures with the high-speed capability of closed chamber systems by using a transfer roller that can be efficiently filled from an open first chamber while operating within a closed second chamber system, achieving both low complexity and high productivity.
Solution Approach 2:
The system uses a dynamically adjustable first chamber pressure that can be increased at higher speeds to prevent air entry, allowing the device to adapt to varying productivity requirements while maintaining structural simplicity of the open ink pan configuration.
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 device ensures uniform coating and prevents air bubbles, allowing for minimum application weights at high speeds by effectively sealing the gap and flushing out air and residue with a high-speed media stream, maintaining coating quality across different production speeds.
Implementation Method 1
The front gap between the lateral surface and the main chamber in the direction of movement of the transfer roller is delimited by a high-speed medium stream flowing out of a nozzle and additionally by a seal
Implementation Method 2
This high-velocity media stream exits the nozzle, which extends across the entire width of the transfer roller, counter to the direction of movement of the transfer roller
Data Source
Figure 1
Figure 2
AI summary
The device has a rotating counter roller (2), a rotating transfer roller (3) for transferring the medium (6) with recesses (4) on its outer surface (5), an application device (10) for filling the recesses with coating medium with a main chamber (12) and a blade (13) bounding a rear gap that contacts the transfer roller surface. A forward gap (16) between the outer surface and main chamber is bounded by a high speed medium emanating from a nozzle (15) perpendicular to the transfer roller or opposite to the movement direction of the transfer roller.