Paper Machine Clothing Seam Preparation via Fabric Folding and Bonding
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Solution Overview
Problem
Existing processes for preparing seam areas in paper machine clothing result in differential dewatering and marking of fibrous webs due to larger void areas and increased production time and expense caused by seam loop formation.
Innovation Solution
A process where weft yarns are removed at a selected seam location, the fabric is folded with aligned warp and weft yarns, and bonded adjacent the window, creating consistent loop size, alignment, and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If seam loops are formed by interdigitating loops and inserting a pintle wire, then the fabric can be joined in an endless form, but the seam area has larger void area resulting in differential dewatering and marking of fibrous web
Solution Approach 1:
The invention removes a specific number of weft yarns (e.g., 3-7 yarns) from the fabric at the seam location to create a window, extracting the problematic interloop structure and replacing it with a bonded seam that eliminates large void areas and prevents differential dewatering
Solution Approach 2:
The invention changes the structural parameters of the seam by controlling the number of removed weft yarns, the dimensions of the window (e.g., 0.5-2 inches), and the bonding parameters to achieve consistent loop size and stiffness while eliminating the harmful void areas
2Ease of manufacture
If seam loops are formed on the base fabric, then the fabric can be joined together, but production time and expense are increased
Solution Approach 1:
By removing weft yarns to create a window and bonding the fabric edges directly, the invention eliminates the time-consuming steps of interdigitating loops and inserting pintle wires, significantly reducing production time
Solution Approach 2:
The invention replaces the mechanical interloop and pintle wire system with a bonding system (thermal, chemical, or mechanical bonding) that is faster to implement and reduces production complexity
3Ease of manufacture
If weft yarns are removed and fabric is folded without aligning yarns, then a seam can be formed, but randomly aligned yarns provide variability of seam properties
Solution Approach 1:
The invention performs preliminary alignment of warp and weft yarns before bonding by folding the fabric edge back on itself, ensuring that yarns are precisely aligned (e.g., within 0.1-0.5 inches) to create consistent loop size, shape, and stiffness
Solution Approach 2:
The invention achieves homogeneity in seam properties by aligning yarns of the same type together, creating uniform loops with consistent dimensions and characteristics throughout the seam, eliminating the variability caused by random yarn alignment
Data Source
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Figure 3
AI summary
A process for preparing a seam area for a PMC base fabric includes the steps of: providing a PMC base fabric including a plurality of warp yarns extending in a machine direction (MD) and a plurality of interwoven weft yarns extending in a cross machine direction (CD); removing a plurality of adjacent weft yarns from the PMC base fabric to define a window of warp yarns not interwoven with weft yarns, the plurality of warp yarns being interwoven with a plurality of weft yarns on either side of the window; folding over the PMC base fabric at the window such that each warp yarn substantially aligns with itself in the MD, and one or more weft yarns on one side of the window substantially align with a respective weft yarn on an opposite side of the window; and bonding together a portion of the PMC base fabric adjacent the window.