Reciprocating Wire Bar Coating for Film Thickness Control
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Solution Overview
Problem
Existing coating methods using wire bars face issues with high coating speed, requiring precise straightness and cylindricity for uniform film thickness, leading to increased operational costs and space requirements due to inadequate drying speed and accuracy.
Innovation Solution
A coating method and device employing a reciprocating rotating wire bar with two distinct rotational speeds and a reciprocating motion to control film thickness and uniformity, reducing precision requirements on the wire bar's straightness and cylindricity, while allowing for increased relative speed and uniform ink distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed wire bar is used for coating, then the coating speed is fast, but the drying operation cannot keep up with the coating speed causing increase of stock and operational costs
Solution Approach 1:
The wire bar is changed from a fixed type to a rotating type. The rotation of the wire bar creates a thinner film coating that dries faster, allowing the coating speed to be maintained or increased while the drying operation can keep up with the coating speed, thereby resolving the contradiction between high productivity and drying time limitations
2Quantity of substance
If a single rotating wire bar is used with the tangential direction same as web moving direction to increase film thickness, then the film thickness is increased, but high precision in straightness and cylindricity is required for uniform thickness
Solution Approach 1:
Instead of rotating the wire bar in the same direction as the web moves (which requires high precision), the wire bar is rotated in the opposite direction to the web moving direction. This inversion of rotation direction allows for increased film thickness while reducing the precision requirements for wire bar straightness and cylindricity, as the relative motion between the wire bar and web creates a more forgiving coating process
3Quantity of substance
If a single rotating wire bar is used with the tangential direction opposite to web moving direction to decrease film thickness, then the film thickness is decreased, but high precision in straightness and cylindricity is still required
Solution Approach 1:
The wire bar rotation direction is set opposite to the web moving direction, which naturally produces a thinner film. This configuration maintains the benefit of reduced precision requirements while achieving the desired film thickness reduction, resolving the contradiction between controlling film thickness and maintaining manufacturing precision
4Reliability
If two wire bars are used with same or reverse rotating directions, then the defects of single wire bar are overcome, but the precision requirements for straightness and cylindricity of each wire bar remain high
Solution Approach 1:
The patent applies the inversion principle by rotating the wire bar opposite to the web moving direction. This single wire bar configuration with opposite rotation achieves reliable and uniform coating while reducing the precision requirements compared to dual wire bar systems where each bar would need high precision straightness and cylindricity
Data Source
AI summary
A coating method has a reciprocating rotating step. A wire bar is rotated at a first rotational speed for coating a film on a web. In a process of rotating the wire bar at the first rotational speed, a tangential direction of the wire bar at a connecting area between the wire bar and the web is opposite to a moving direction of the web, and then the wire bar is rotated to restore to an original position at a second rotational speed. Meanwhile, the tangential direction is changed and is same to the moving direction of the web. The second rotational speed is far faster than the first rotational speed. A coating device has a base, the wire bar disposed across the base, and a rotation adjusting module connected to the wire bar for driving the wire bar to rotate reciprocatingly.