TAD Fabric Knuckle Pattern for Sheet Transfer
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Solution Overview
Problem
Existing through-air-drying (TAD) fabrics for papermaking lack enhanced support in both machine direction (MD) and cross-machine direction (CD), which limits sheet transfer to the Yankee dryer and creping efficiency, resulting in suboptimal bulk and absorbency in tissue products.
Innovation Solution
A TAD fabric with a weave pattern featuring long knuckles in both warp and weft directions, where warp yarns float over multiple weft yarns, and selected knuckles are flattened to increase contact area, facilitating sheet transfer and creping, and defining pocket areas for improved bulk and absorbency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional TAD fabrics with standard weave patterns are used, then the fabric structure is simple and easy to manufacture, but the sheet transfer to Yankee dryer and creping efficiency are insufficient
Solution Approach 1:
The fabric surface is segmented into distinct functional zones: raised knuckle areas for sheet contact and transfer, and recessed pocket areas for bulk creation and absorbency. This segmentation allows different regions to perform specialized functions, improving overall sheet transfer efficiency and creping performance while maintaining a systematic weave structure.
Solution Approach 2:
The fabric exhibits local quality variations through the weave pattern, with raised knuckles providing high contact area for sheet transfer in specific locations, while pocket areas provide low contact for bulk formation. This localized functional differentiation resolves the contradiction by enhancing productivity in critical areas without requiring complex fabrication processes across the entire fabric.
2Productivity
If TAD fabrics with long knuckles in both warp and weft directions are used, then MD and CD contact area is enhanced for improved sheet transfer and creping, but the fabric manufacturing complexity increases
Solution Approach 1:
The weave pattern creates asymmetric fabric surfaces with raised knuckles of varying lengths and positions in warp and weft directions. This asymmetry generates the desired long knuckle morphology that enhances sheet contact and transfer in both MD and CD, while the asymmetric structure is achieved through standard weaving techniques rather than complex post-processing.
Solution Approach 2:
The knuckles are formed with curved, rounded contours rather than sharp angles, creating smooth transitions between raised and recessed areas. This curvature enhances the contact area with the sheet by distributing pressure more evenly, while the curved knit structure is accomplished through conventional weave patterns that alternate yarn elevations.
3Productivity
If knuckles are flattened to increase contact area, then sheet transfer and creping are improved, but the fabric surface uniformity may be compromised
Solution Approach 1:
The fabric structure is designed to be dynamically adaptive, with the raised knuckles providing variable contact areas that adjust during the sheet transfer and creping processes. The flattening of knuckles creates a dynamic interface that increases effective contact area under operational conditions while maintaining the overall uniform appearance of the fabric surface when at rest.
Solution Approach 2:
The fabric utilizes three-dimensional knuckle structures that extend vertically from the fabric plane, creating additional contact dimension. When knuckles are flattened, this vertical dimension is converted into increased horizontal contact area, improving sheet transfer while the periodic repetition of this pattern across the fabric maintains surface uniformity.
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 fabric provides enhanced MD and CD contact, improving sheet transfer and creping, leading to increased bulk and absorbency in tissue products, while maintaining uniform appearance and structural integrity.
Implementation Method 1
transferred to a through-air-drying (TAD) fabric or belt by means of an air flow, brought about by vacuum or suction, which deflects the web and forces it to conform
Implementation Method 2
passes through a through-air dryer, where a flow of heated air, directed against the web and through the TAD fabric or belt, dries the web to a desired degree
Implementation Method 3
a flow of heated air, directed against the web and through the TAD fabric or belt, dries the web
Data Source
Figure 1
Figure 2
AI summary
A through-air-drying (TAD) fabric for producing tissue paper and related products on a papermaking machine comprising a plurality of warp yarns interwoven with a plurality of weft yarns to produce warp and weft knuckles on a paper-side surface of the fabric, preferably to form an L-shaped knuckle pattern.