Watermark Formation Element with Integrated Drainage Channels
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Solution Overview
Problem
Current cylinder mould watermark processes face challenges in creating complex, multi-tonal designs with sharply contrasting dark and light areas due to limitations in embossing wire cloth strength, difficulty in integrating electrotype watermarks, and increased production costs and time.
Innovation Solution
A watermark formation element with an integrated body featuring a contoured watermark forming surface and drainage channels, allowing for controlled fibre deposition and drainage to create high-contrast tonal variations, and can be produced using 3D printing for enhanced flexibility and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wire cloth is embossed to create high-contrast watermarks, then the watermark image sharpness is improved, but the wire cloth strength is reduced and damage risk increases
Solution Approach 1:
The watermark formation element is divided into multiple independent components: a support structure (wire cloth or alternative substrate) and a separate embossed watermark layer. This segmentation allows the watermark layer to be highly detailed without compromising the structural integrity of the support, as the embossing is confined to the watermark layer rather than the entire wire cloth assembly.
Solution Approach 2:
The invention uses a composite structure combining a support structure with a watermark formation layer made of different material properties. The watermark formation layer can be embossed with high verticality while the support structure maintains overall strength. The composite construction allows each layer to fulfill its specific function without the limitations of a homogeneous structure.
2Manufacturing precision
If finer wire is used to improve watermark resolution, then the image clarity is improved, but the mould cover durability is reduced
Solution Approach 1:
By separating the watermark formation function from the structural support function, the invention allows the use of fine-detail embossing in the watermark layer without requiring the entire wire cloth to be made of fine, durable material. The support structure can use coarser, more durable wiring while the watermark layer provides high resolution.
Solution Approach 2:
The watermark formation layer is designed with locally optimized properties for high-resolution imaging in the areas where watermarks are formed, while the support structure maintains overall durability. The embossed features are concentrated in specific local regions rather than requiring the entire wire cloth to have fine characteristics throughout.
3Manufacturing precision
If deep embossing is used to create dark watermark regions, then the tonal contrast is improved, but the fibre movement and drainage control become difficult
Solution Approach 1:
The invention extracts the drainage control function from the embossed wire cloth structure and implements it through a separate drainage layer or modified drainage system. This allows deep embossing for high contrast without the complexity of controlling fibre movement through the embossed features themselves, as drainage is managed independently.
Solution Approach 2:
An intermediary drainage layer or drainage control mechanism is introduced between the embossed watermark layer and the water reservoir. This intermediary structure facilitates controlled drainage and fibre movement without interfering with the deep embossing required for high tonal contrast, decoupling the two functions.
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
Enables the production of complex, high-contrast watermarks with improved durability and reduced production time and costs, allowing for customized and flexible designs in papermaking.
Implementation Method 1
controlled fibre deposition and drainage to create high-contrast tonal variations
Data Source
Figure 1~2b
Figure 3a
Figure 3b~3d
AI summary
The present invention relates to a watermark formation element for forming watermarks in paper, a cylinder mould cover comprising such a watermark formation element, a method of making such a cylinder mould cover, a method of making paper using such a cylinder mould cover and paper made thereby. The watermark formation element has an integrated body comprising a watermark forming surface, which has one or more watermark forming regions, and a drainage surface. A plurality of drainage channels extend from front surface apertures in the watermark forming surface to the drainage surface. At least some of the front surface apertures are shaped to define at least one of an alphanumeric, a symbol or a pictorial image. A filter layer (36) located between the watermark forming surface (21) and the drainage surface (25) having filter layer apertures which have a maximum width which is less than a smallest width of the front surface apertures.