Seamed Press Felt with Monofilament Seam Support for Reduced Marking
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Solution Overview
Problem
Existing press felts, particularly multiaxial constructions, suffer from sheet marking and reduced strength at the seam due to differences in physical characteristics, leading to potential sheet breaks and imperfections in the finished paper.
Innovation Solution
A seamed press felt design with CD monofilament support yarns in loop open spaces, interdigitated MD loops, and a pintle channel, ensuring uniform air permeability and seam quality by filling at least 25% of the loop area with CD monofilament yarns having a diameter at least 1.6 times that of CD oriented yarns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiaxial press felts are used to reduce manufacturing time and costs, then productivity is improved, but sheet marking and seam strength are worsened due to physical characteristic differences at the seam
Solution Approach 1:
The patent applies local quality by inserting support yarns specifically at the seam location rather than throughout the entire fabric. The support yarns are placed in the loop open spaces at the seam region where MD oriented yarns form loops, providing localized reinforcement exactly where the seam marking and strength issues occur, without affecting the overall multiaxial construction efficiency
Solution Approach 2:
The patent uses composite materials by combining different yarn types (MD oriented yarns, CD oriented yarns, and support yarns) with different properties in a single fabric structure. The support yarns have different physical characteristics than the base fabric yarns, creating a composite structure that addresses the seam weakness while maintaining the multiaxial fabric's productivity benefits
2Ease of manufacture
If seam loops are formed by interdigitating MD yarns and inserting a pintle, then the fabric can be joined continuously, but loop open spaces create non-uniform air permeability and sheet marking
Solution Approach 1:
The support yarns are locally inserted only in the loop open spaces at the seam region, providing targeted filling where the air permeability non-uniformity occurs. This localized intervention maintains the overall ease of seam joining while correcting the specific air flow issues at the seam location
Solution Approach 2:
The patent addresses the porous nature of the loop open spaces by filling them with support yarns. The support yarns modify the porous structure of the seam region, creating a more uniform air permeability profile that matches the non-seam regions, while still allowing the pintle to pass through the formed loops
Data Source
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AI summary
A seamed press felt formed from a base fabric having a CD width and a MD length with two opposing MD ends that are joined to form a continuous belt. MD oriented yarns form uniform loops at the two opposing MD ends that are interdigitated to define a pintle channel extending across the CD width. CD oriented yarns are connected to the MD oriented yarns, in a woven or nonwoven construction. Loop open spaces are located within the loops on each of the two opposing MD ends in a seam region, with the loop open spaces being defined between a last one of the CD yams at each of the two opposing MD ends and the pintle channel. At least one CD monofilament support yarn is located in the loop open spaces on each of the two opposing MD ends. A pintle extends through the pintle channel to form a seam.