Papermaking Wire Cross Threads with Variable Float Lengths
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Solution Overview
Problem
Paper machine screens with different materials for lower transverse threads often result in inconsistent contact with the paper machine, affecting screen operation and paper quality due to differing material behaviors, leading to reduced operating time and increased material loss.
Innovation Solution
The lower transverse threads are inconsistently bound into the fabric layer to compensate for their different behaviors, allowing for a consistent projection and extended operating time, and enabling the use of a wider range of materials, including polyamide and polyester, with varying diameters and thermosetting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If different materials (polyester and polyamide) are used for lower transverse threads to enhance abrasion resistance and extend operating time, then the screen's durability is improved, but the threads exhibit inconsistent behavior leading to inconsistent contact with the paper machine and reduced paper quality
Solution Approach 1:
The patent applies local quality by differentiating the binding pattern for different material groups within the same fabric. Polyester threads are bound every 4th longitudinal thread while polyamide threads are bound every 6th longitudinal thread. This localized differentiation compensates for the inherently different behavioral characteristics of each material, ensuring that each material group contacts the paper machine consistently throughout its operational life, thereby resolving the contradiction between extended operating time and contact consistency.
2Strength
If different materials with different properties are used for lower transverse threads to improve mechanical stability and abrasion resistance, then the screen's mechanical performance is enhanced, but the threads project differently on the running side requiring additional grinding and causing material loss
Solution Approach 1:
The patent implements local quality by assigning different binding frequencies to different material groups: polyester threads are bound every 4th longitudinal thread while polyamide threads are bound every 6th longitudinal thread. This differentiated local binding pattern compensates for the different shrinkage and projection behaviors of each material, resulting in a running side where all threads project consistently without requiring additional grinding operations, thereby eliminating material loss while maintaining enhanced mechanical stability.
3Ease of manufacture
If consistent binding of lower transverse threads is used to simplify manufacturing, then the production process is streamlined, but threads made from different materials exhibit inconsistent behavior and projection due to their different properties
Solution Approach 1:
The patent resolves this contradiction by applying local quality through differentiated binding patterns: polyester threads are bound every 4th longitudinal thread while polyamide threads are bound every 6th longitudinal thread. This approach maintains relative manufacturing simplicity while achieving precise control over thread projection uniformity. The localized differentiation in binding frequency compensates for material property differences, ensuring that threads from different materials project consistently on the running side without requiring post-manufacturing adjustments.
Data Source
AI summary
A sheet-forming wire with a lower fabric layer formed from a multiplicity of identically constructed lower weave repeats, each of which contains longitudinal threads extending in the lower fabric layer, and lower cross threads, with the lower cross threads extend only in the lower fabric layer. The lower cross threads are tied into the lower fabric layer in each case by exactly two longitudinal threads extending in the lower fabric layer, in that each particular lower cross thread is run under by a first longitudinal thread at a first tying-in point (x) and is run under by a second longitudinal thread at a second tying-in point (x). The lower cross threads form first lower cross threads (I) and second lower cross threads (II). The first lower cross threads form a shorter float on the running side than the second lower cross threads.