Watermark Formation Element for Multi-Tonal Paper
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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, drainage control, and the difficulty of integrating electrotype watermarks, leading to reduced security and increased production costs.
Innovation Solution
A watermark formation element with a contoured surface and drainage channels extending from front surface apertures to a drainage surface, allowing for varied tonal variation and improved drainage control, which can be 3D printed and integrated into the cylinder mould cover to enhance watermark quality and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wire cloth is embossed to create watermark patterns, then watermark detail and contrast are improved, but the strength and durability of the mould cover deteriorates
Solution Approach 1:
The watermark formation element is separated from the wire cloth structure. Instead of embossing the wire cloth itself, a distinct formation element with integrated drainage channels is attached to the mould cover, allowing watermark creation without compromising wire cloth integrity
Solution Approach 2:
A watermark formation element acts as an intermediary between the wire cloth and the watermark pattern. This element provides the embossed features needed for watermark detail while the wire cloth maintains its structural strength and durability
2Manufacturing precision
If finer wire is used to improve watermark resolution, then image clarity is improved, but mould cover durability deteriorates due to faster wear
Solution Approach 1:
The system combines a durable wire cloth base with a separate watermark formation element that can be optimized for resolution. The formation element can use materials and structures specifically designed for high-detail watermarking without compromising the overall durability of the mould cover assembly
3Manufacturing precision
If drainage rate is increased to improve fibre deposition control, then watermark tonal variation is improved, but fibre density in watermark regions deteriorates
Solution Approach 1:
The drainage channels are strategically positioned and dimensioned to provide localized drainage control. Different regions of the formation element can have different drainage characteristics, allowing precise control of fibre deposition and watermark tonal variation in specific areas without affecting overall fibre density
Solution Approach 2:
The drainage channel geometry (size, shape, distribution) is varied to control drainage rate and fibre deposition. By adjusting these parameters, the system achieves desired watermark tonal variation while maintaining appropriate fibre density in different watermark regions
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 creation of complex, multi-tonal watermarks with improved contrast and security features, reducing production time and costs by allowing for flexible design and material usage, while maintaining durability and clarity.
Implementation Method 1
As the mould cylinder rotates, water is drawn through the wire cloth depositing fibres onto the cylinder surface
Implementation Method 2
water is drawn through the wire cloth depositing fibres onto the cylinder surface
Data Source
Figure 1~2b
Figure 3a
Figure 3b~3d
AI summary
The invention relates to a watermark formation element for forming multi-tonal 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, said watermark formation element having a plurality of drainage channels extending from front surface apertures in the watermark forming surface to the drainage surface. The shape of, size of, and/or spacing between, the front surface apertures in a given horizontal plane, which is parallel to the drainage surface, is varied in the one or more watermark forming regions to create tonal variation in paper formed on said watermark formation element.