Flat Woven Press Fabric Seam Structure to Eliminate Moiré
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Solution Overview
Problem
Current press fabrics in papermaking processes face issues such as the Moiré Effect, discontinuities at seams, and caliper variation, which affect the smoothness and reliability of the paper sheet production, leading to sheet marking and non-uniform pressure distribution.
Innovation Solution
A flat woven full-width on-machine-seamable base fabric is developed, with specific demarcated regions and yarn densities, and layers are laminated using staple fiber batt material, allowing for improved seam loop orientation and parallelism, and eliminating the Moiré Effect through a single event loop formation technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional woven base fabrics are used with needled nonwoven batt, then the fabric can support and carry the paper product through press nips, but the Moiré Effect occurs causing sheet marking and non-uniform pressure distribution
Solution Approach 1:
The fabric is divided into multiple layers with different constructions. The base fabric layer has a plain weave pattern while the intermediate layer has a different weave pattern (e.g., twill or satin), segmenting the uniform structure that causes Moiré Effect. This layering breaks up the repetitive interference patterns while maintaining the fabric's support function.
Solution Approach 2:
The fabric uses a composite structure combining different fabric layers with distinct weave patterns and yarn configurations. This composite approach creates a multi-layered system where the interaction between different patterns eliminates Moiré Effect while preserving the necessary mechanical properties for paper support and water drainage.
2Productivity
If seams are formed by interdigitating loops from modified endless weaving, then the fabric can be made endless for continuous operation, but discontinuities and migrating CD yarn ends occur at the seam
Solution Approach 1:
The problematic seam formation process is extracted and replaced. Instead of using modified endless weaving with interdigitated loops that create discontinuities, the patent employs conventional weaving methods that produce seamless or minimally seamed fabrics, removing the source of migrating yarn ends and seam defects.
Solution Approach 2:
The fabric is designed with preliminary considerations for seamless construction. By planning the weave structure and edge configurations in advance to minimize or eliminate seams, the patent prevents discontinuities before they occur, ensuring continuous operation without migrating yarn ends.
3Manufacturing precision
If flat woven full width on-machine-seamable base fabric with demarcated regions is used, then seam loop orientation and parallelism are improved eliminating Moiré Effect, but the manufacturing process becomes more complex
Solution Approach 1:
Different regions of the fabric have different local qualities - the demarcated regions have specific weave patterns or yarn configurations that differ from the main body. This local variation enables proper seam loop formation and orientation at critical areas without compromising the overall fabric structure, achieving precision where needed while maintaining simplicity elsewhere.
Data Source
AI summary
A laminated on-machine-seamable industrial fabric made from a flat woven full width base fabric layer wherein the base fabric layer is folded inwardly and flattened to produce a fabric with seaming loops disposed at the two widthwise edges.