Press Felt Welded Thread Structure for Compaction Resistance
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Solution Overview
Problem
Press felts used in paper and board production experience compaction due to repeated stresses in press nips, leading to reduced permeability and liquid absorption volume, necessitating additional measures like sacrificial fleece layers that incur extra costs.
Innovation Solution
A press felt design with a woven base structure featuring intersecting longitudinal and transverse threads welded at specific intersection points, particularly using bi-component fibers or laser-induced welding, to stabilize the fabric layers and prevent compaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple fabric layers are used to increase liquid absorption volume, then the void volume increases, but the tendency to compact increases
Solution Approach 1:
The patent applies preliminary action by welding a proportion of intersection points between threads before the felt enters service. This pre-fixation prevents threads from being pressed into each other during operation, thereby preventing compaction while maintaining the multi-layer structure needed for liquid absorption. The welding is performed in advance at manufacturing, so the felt starts service with threads already fixed in position.
2Stability of the object's composition
If threads are welded at more intersection points, then thread displacement is prevented and compaction is reduced, but the stiffness of the basic structure increases
Solution Approach 1:
The patent applies local quality by welding only a specific proportion of intersection points (between 5% and 50%) rather than all intersection points. This selective welding creates local fixation zones that prevent thread displacement and compaction while leaving other areas flexible. The localized welding approach balances compaction resistance with maintaining the necessary softness and conformability of the felt.
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 maintains permeability and liquid absorption capacity by preventing thread displacement and compaction, reducing the need for costly sacrificial layers while maintaining structural integrity.
Implementation Method 1
the longitudinal threads and the transverse threads of the first fabric layer are welded together at at least 5% of the intersection points
Implementation Method 2
particularly using bi-component fibers or laser-induced welding, to stabilize the fabric layers and prevent compaction
Data Source
Figure 1
Figure 2a~3
AI summary
The invention relates to a press felt for a machine for producing a fibrous material web, comprising a woven base structure and a nonwoven support fixed thereon, wherein the base structure comprises a first fabric layer and a second fabric layer, wherein at least the first fabric layer has longitudinal threads and transverse threads which intersect at intersecting points, wherein the longitudinal threads and the transverse threads of the first fabric layer are integrally bonded to each other, in particular welded to each other, at at least 5% of the intersecting points, in particular at at least 10% of the intersecting points.