Transverse Zone Drying Control for Uniform Paper Web Moisture
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Solution Overview
Problem
Existing drying units for printing materials, particularly in digital inkjet printing, fail to achieve uniform moisture distribution, leading to uneven drying and mechanical property issues such as warping and brittleness, due to inhomogeneous solvent/water application and uneven ink coverage.
Innovation Solution
The method involves controlling multiple drying and moistening elements transversely to the printing material's transport direction to apply varying drying and moistening intensities based on real-time sensor data and print data, ensuring uniform relative humidity by differentiating drying or moistening zones across the material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform drying intensity is applied across the entire printing material web, then the drying process is simple to control, but the moisture distribution remains uneven due to variable ink coverage and water application
Solution Approach 1:
The printing material web is divided into multiple transverse zones, each equipped with independently controllable drying elements and moistening elements. This segmentation allows different drying intensities to be applied to different zones based on their specific moisture requirements, thereby achieving uniform moisture distribution across the entire web while managing complexity through modular zone control
Solution Approach 2:
Each transverse zone is assigned specific drying and moistening characteristics tailored to its local moisture needs. Zones with higher ink coverage receive different treatment than zones with lower coverage, creating locally optimized drying conditions that collectively achieve global uniformity without requiring overly complex centralized control
2Quantity of substance
If high drying intensity is applied to remove excess moisture, then the moisture content is reduced, but the printing material becomes too dry and brittle
Solution Approach 1:
The drying intensity parameters are dynamically adjusted based on the specific moisture content requirements of each transverse zone. By controlling drying elements to apply appropriate heat and airflow intensity to each zone, the system removes excess moisture while maintaining sufficient moisture to preserve the mechanical properties and prevent brittleness
Solution Approach 2:
The system uses sensors to detect the moisture content and drying state of each zone in real-time, feeding this information back to the control system. Based on this feedback, the drying and moistening elements adjust their intensity dynamically, ensuring moisture is removed to the optimal level without over-drying and damaging the mechanical properties
3Manufacturing precision
If drying elements are controlled individually to achieve uniform drying, then moisture distribution improves, but the system complexity and control difficulty increase
Solution Approach 1:
The system divides the drying process into manageable transverse zones with individually controllable elements. This segmentation transforms the complex task of controlling the entire web into simpler, independent zone controls, making the system easier to operate while achieving uniform drying results
Solution Approach 2:
Each transverse zone is equipped with both drying elements and moistening elements that can be controlled through a unified control system. This multi-functional approach allows the same control architecture to manage both drying and moistening operations across all zones, simplifying operation despite the individual control capabilities
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 approach compensates for inhomogeneous moisture distribution, achieving a constant and optimal residual moisture level, enhancing processing stability and quality by ensuring uniform drying and moistening across the printing material.
Implementation Method 1
drying units are therefore used in the prior art, which dry the printing material by means of heating elements
Implementation Method 2
Each of these drying elements includes a heating element to heat up the ambient air
Implementation Method 3
a fan that directs the warm air in the direction of the web of printing material
Data Source
Figure 1~2
AI summary
A method for changing the relative humidity of a substrate (2) by means of a drying unit (1) comprising a number of drying elements (14) arranged transversely to the transport direction (x) of the substrate (2) and directed towards the substrate (2) to dry it with a specific drying intensity, wherein the individual control of the drying elements (14) is intended to enable particularly uniform drying of the substrate web or the print in the simplest possible manner, so that an optimal and uniform degree of dryness with a desired residual moisture content is achieved for the substrate web and further processing. For this purpose, at least two drying elements (14) are controlled such that at least two areas transversely to the transport direction (x) of the substrate (2) are subjected to different drying intensities.