Paper Machine Fabric Top Side Weave Design for Mark-Free Dewatering
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Solution Overview
Problem
Existing paper machine fabrics, particularly those with a double-layer or three-layer structure, face issues with low water permeability and unwanted fabric markings due to closely arranged machine-direction threads and the inability to produce an ideal plain weave, leading to reduced dewatering capacity and potential layer separation during operation.
Innovation Solution
A paper machine fabric with a top side featuring a large number of longitudinal threads interwoven with transverse threads, where the transverse thread repeat is three times as many as the longitudinal thread repeat, allowing for a design that approximates a plain weave while maintaining high drainage and robustness, and can be adapted by varying the number of longitudinal threads in the repeat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If machine-direction threads are arranged closely next to one another to achieve a robust machine side, then the machine side robustness is improved, but water permeability deteriorates
Solution Approach 1:
The fabric is designed with different thread arrangements for different sides: the machine side has closely arranged machine-direction threads for robustness, while the paper side has a plain weave pattern with improved water permeability. This local differentiation allows each side to optimize for its specific function without compromising the other.
2Stability of the object's composition
If a double-layer fabric structure is used to achieve a robust machine side and fine paper side, then the fabric stability is improved, but water permeability deteriorates
Solution Approach 1:
The fabric combines two different weave structures in a single composite structure: a plain weave layer for the paper side and a layer with closely arranged threads for the machine side. This composite approach allows the fabric to simultaneously achieve the fine surface quality needed for paper formation and the structural stability needed for machine operation, while maintaining adequate water permeability through the optimized plain weave pattern.
3Stability of the object's composition
If separate binding threads are used to connect fabric layers, then the layer connection is improved, but the fabric structure complexity increases
Solution Approach 1:
The binding function is merged into the existing weave structure by using the same longitudinal and transverse threads to both form the fabric pattern and connect the layers. This integration eliminates the need for separate binding threads and reduces structural complexity while maintaining layer connection stability.
4Manufacturing precision
If the transverse thread repeat contains many threads to improve uniformity, then the paper side uniformity is improved, but the fabric thickness increases
Solution Approach 1:
The patent optimizes the thread repeat parameters to achieve the desired balance. By carefully selecting the number of threads in the repeat and their spacing, the fabric achieves high uniformity for mark-free paper production while controlling the overall thickness to maintain dewatering capacity. The plain weave pattern with optimized repeat dimensions allows sufficient thread density for uniformity without excessive layer buildup.
Data Source
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AI summary
The invention relates to an upper side, in particular a paper side for a multiple-layer sheet-forming fabric, in particular provided for use in a wet end of a papermaking machine, which comprises a multiplicity of longitudinal threads (21, 22, 23, ...) which are woven with a multiplicity of transverse threads (1, 2, 3, ...) and in the process form repeats in the longitudinal and transverse direction, wherein the transverse-thread repeat contains at least three times as many threads as the longitudinal-thread repeat and the longitudinal-thread repeat comprises at least three threads (21, 22, 23) and the transverse-thread repeat comprises at least nine (1, 2, 3, ..., 9), wherein all longitudinal threads run alternately over three transverse threads (1, 3, 5) and under three transverse threads (2, 4, 6) and subsequently under the remaining transverse threads (7, 8, 9, ...), and wherein two directly adjacent longitudinal threads (21 and 22, 22 and 23, 23 and 24, ...) are displaced with respect to one another in the longitudinal direction by at least three transverse threads. Furthermore, the invention relates to a papermaking-machine fabric having the upper side which is described in the preceding text.