Alternating Float Dryer Fabric for Uniform Paper Drying
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Solution Overview
Problem
Existing dryer fabrics in paper machines do not achieve uniform drying and have limited service life, necessitating an alternative configuration that enhances contact surface area and abrasion volume for improved performance.
Innovation Solution
A dryer fabric with alternating longitudinal thread floats on both sides, overlapping multiple transverse threads, providing a symmetrical construction with increased contact points and area, and allowing for uniform, torsion-free seam loop orientation, using warp and weft threads with specific cross-sectional dimensions and materials like PPS, PET, or PEEK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional dryer fabric construction is used, then the fabric can be manufactured with standard weaving processes, but the contact surface area on the paper side is insufficient for uniform drying
Solution Approach 1:
The patent applies asymmetry by creating different float patterns on the paper side versus the machine side of the fabric. The paper side features longer floats that extend over multiple transverse threads to maximize contact surface area, while the machine side has shorter floats for durability. This asymmetric construction optimizes each side for its specific function: the paper side for uniform drying contact and the machine side for abrasion resistance.
Solution Approach 2:
The patent extends the fabric structure into the third dimension by creating raised float surfaces on the paper side. The longitudinal threads float over multiple transverse threads, creating elevated contact surfaces that increase the effective contact area with the paper web. This dimensional change transforms a traditionally two-dimensional fabric surface into a three-dimensional textured surface for improved drying performance.
2Reliability
If the fabric is designed with increased contact points for uniform drying, then drying performance improves, but the service life is reduced due to higher abrasion
Solution Approach 1:
The patent applies local quality by giving different regions of the fabric different properties. The paper side is designed with longer floats and higher contact points for optimal drying uniformity, while the machine side is designed with shorter floats and enhanced durability features for abrasion resistance. Each side is locally optimized for its specific functional requirements rather than using a uniform construction throughout.
Solution Approach 2:
The asymmetric float construction allows the fabric to have different characteristics on each side: the paper side with longer floats for drying performance and the machine side with shorter floats for durability. This asymmetry resolves the contradiction by allowing each side to be optimized independently for its primary function.
3Area of stationary object
If longitudinal threads are crimped over individual transverse threads, then the fabric structure is simplified, but the contact area percentage decreases below the optimal 35-45% range
Solution Approach 1:
The patent changes the parameters of the float configuration by specifying that longitudinal threads should float over a defined number of transverse threads (typically 2-5 threads) rather than being crimped over individual threads. This parameter change increases the contact area percentage to the optimal 35-45% range while maintaining a systematic float pattern that balances complexity with manufacturability.
4Ease of manufacture
If seam loops are oriented to accommodate weaving patterns, then manufacturing is easier, but the seam loops become torsioned and misaligned
Solution Approach 1:
The asymmetric float pattern is designed to accommodate the seam loop orientation requirements. By carefully configuring the float lengths and patterns, the fabric can be woven with seam loops that are both properly oriented for easy manufacturing and correctly aligned without torsion. The asymmetry in the float pattern compensates for the twisting that would otherwise occur in the seam loops.
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
The solution results in a high Fabric Fineness Index on both sides, ensuring even heating and drying with a longer service life and improved seam loop orientation, enhancing the fabric's durability and efficiency.
Implementation Method 1
the paper web is guided over heated drying cylinders, as a result of which the paper web is thermally dewatered
Data Source
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AI summary
The invention relates to a drying screen suitable for use in the drying section of a paper machine, with a paper side intended for the support of a paper web and a machine side facing away from the paper side, wherein the drying screen has or consists of a fabric of longitudinal (2-7) and transverse threads (10-21) comprising at least two superimposed transverse thread layers, wherein the longitudinal threads bind the transverse threads in paper-side and machine-side floats alternating on the paper-side and machine-side, and the fabric has exclusively longitudinal thread floats on both the paper-side and machine-side, each of which overlaps at least two adjacent transverse threads, and all longitudinal thread floats overlap the same number of transverse threads.