Press Fabric Weft Arrangement for Pulp Machine Dewatering
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Solution Overview
Problem
Conventional press fabrics for pulp machines suffer from deteriorating water sucking and dewatering properties due to blocked dewatering channels, poor washability, rigidity, size stability, and increased electric load, leading to inefficient pulp sheet dewatering over time.
Innovation Solution
A multilayer press fabric with monofilaments as warps and yarns forming fine water-sucking spaces as wefts, arranged vertically and alternately, maintains dewatering channels and water retention capabilities by preventing flattening of monofilaments and ensuring efficient water transfer through capillary action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If yarns having fine water-sucking space are used as wefts to achieve excellent water sucking property, then water sucking property is improved, but the yarns are flattened and widened by press pressure blocking dewatering channels, leading to deterioration in water sucking and dewatering properties over time
Solution Approach 1:
The weft layer is segmented into multiple rows with alternating yarn types: some rows contain yarns with fine water-sucking spaces for water absorption, while adjacent rows contain monofilaments that maintain structural stability. This segmentation allows different parts of the fabric to perform different functions - water absorption versus structural support - preventing the flattening of all yarns under press pressure.
Solution Approach 2:
Different regions of the fabric have different properties: the yarns with fine water-sucking spaces provide local water absorption capability, while the monofilament regions provide local structural rigidity and resistance to flattening. This local differentiation of properties allows the fabric to simultaneously achieve good water sucking property and maintain dewatering channels over time.
2Reliability
If needle felt is used as water sucking medium to achieve smooth water passage, then water sucking property is improved, but dirt and chemicals penetrate into the felt cannot be removed easily and high-pressure shower breaks holes in it
Solution Approach 1:
The fabric uses a porous woven structure with monofilaments and multifilament yarns that create interconnected voids for water passage. This porous structure allows water to pass smoothly through capillary action while the woven configuration provides mechanical strength to resist damage from high-pressure showering and chemical exposure, unlike dense needle felt.
Solution Approach 2:
The fabric combines different fiber types and structures - monofilaments for structural integrity and multifilament yarns with fine water-sucking spaces for water absorption. This composite structure provides both the water sucking property and the durability needed to withstand washability and shower resistance requirements.
3Reliability
If batt of fine synthetic fibers is used to fill needle felt structure, then water sucking property is improved, but the batt is gradually flattened and compressed leading to deterioration in water sucking property
Solution Approach 1:
The fabric structure is designed to be dynamically adaptable under press pressure: the yarns with fine water-sucking spaces can compress slightly during pressing to allow water passage, while the monofilament rows maintain overall structural stability. This dynamic behavior prevents permanent flattening and compression of the entire fabric, preserving water sucking property over time.
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 press fabric effectively retains water sucking and dewatering performance for a longer period, maintaining pulp sheet water content at a usable level and resisting high-pressure washing, while maintaining structural integrity and preventing dirt accumulation.
Implementation Method 1
efficient water transfer through capillary action
Data Source
Figure 1~2
Figure 3~4
AI summary
In a press fabric for a pulp machine having a multilayer structure, which fabric is woven using, as a warp, a monofilament as a warp and, as wefts, a yarn obtained by bundling raw yarns of a small diameter and forming a fine water sucking space therebetween and a monofilament, at least an upper surface side weft and a lower surface side weft are arranged vertically as the wefts; the yarns forming a fine water-sucking space and monofilament are used as wefts constituting the lower side layer; they are arranged at a ratio of 2:2 or 1:2; and two monofilaments are arranged adjacent to each other as the lower surface side wefts, whereby the press fabric can maintain its dewatering channel for discharging water to the back surface side from the initial stage to the final stage of use.