Seamed Forming Felt Structure for Durable Tissue Machine Operation
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Solution Overview
Problem
Conventional seam felts used as forming felts in tissue machines suffer from a weak seam that is prone to damage due to the impact of the stock jet at high production speeds, leading to a short service life and operational inefficiencies.
Innovation Solution
A seam felt with a single-layer or multi-layer base structure featuring MD threads with a specific diameter and density, combined with a thinner nonwoven layer, which takes over the functionality of the nonwoven fabric, ensuring a stable and durable forming felt for tissue machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional felt is used in tissue machines, then the felt can be processed, but it causes blockages in the felt processing machine and requires frequent stopping for cleaning
Solution Approach 1:
The felt is segmented into multiple layers (first felt layer, second felt layer, and intermediate layer) with distinct functions. The intermediate layer acts as a barrier that prevents blockages while allowing continuous processing, dividing the single felt structure into functional segments that address the blockage issue.
Solution Approach 2:
The invention uses composite construction by combining different felt layers with an intermediate layer made of different material properties. This composite structure integrates the advantages of each layer to achieve both continuous processing capability and blockage resistance, resolving the contradiction between productivity and reliability.
2Productivity
If felt is processed continuously without interruption, then productivity increases, but the felt becomes misaligned and requires frequent stopping for realignment
Solution Approach 1:
The felt structure is segmented into multiple layers with the intermediate layer positioned between them. This segmentation allows each layer to maintain its alignment independently while enabling continuous processing, preventing the misalignment that occurs in single-layer continuous processing.
Solution Approach 2:
The intermediate layer has different material properties compared to the outer felt layers, creating local quality differences that enhance alignment stability. This local variation in material properties allows the intermediate layer to act as an alignment reference, maintaining precision during continuous processing.
3Ease of manufacture
If the felt structure is simplified to a single layer, then manufacturing is easier, but it causes blockages and requires frequent cleaning interruptions
Solution Approach 1:
The felt is divided into multiple layers with the intermediate layer serving as a blockage-preventing barrier. This segmentation allows continuous operation without cleaning interruptions while maintaining reasonable manufacturing complexity, resolving the contradiction between ease of manufacture and productivity.
Solution Approach 2:
The composite structure combines multiple felt layers with an intermediate layer to achieve continuous operation capability. While slightly more complex than single-layer construction, the composite approach enables uninterrupted productivity, justifying the additional manufacturing steps through continuous operation benefits.
4Strength
If felt layers are tightly bound together, then structural integrity is improved, but it causes misalignment during processing and requires stopping for realignment
Solution Approach 1:
The intermediate layer has different binding characteristics compared to the outer felt layers, creating local quality differences in the structure. This allows the outer layers to remain tightly bound for integrity while the intermediate layer provides alignment stability, resolving the contradiction between strength and precision.
Solution Approach 2:
The composite structure combines layers with different material properties and binding characteristics. This allows each layer to fulfill its specific function - outer layers provide structural integrity through tight binding, while the intermediate layer maintains alignment through its unique properties, resolving the contradiction between strength and manufacturing precision.
Data Source
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AI summary
The invention relates to a seamed felt for use in a machine for producing a tissue web, comprising a single-layer or multilayer base structure which has a textile structure with MD threads that form seam loops on both end-face edges of the base structure. The fabric can be made continuous by connecting the end-face edges of the fabric by means of a seam, and the seam can be produced by interlocking the seam loops of both end-face edges and introducing a plug element. The seamed felt additionally comprises at least one layer of nonwoven fibers. The invention is characterized in that the MD threads predominantly or as a whole have a diameter ranging between 0.25 mm and 0.45 mm, in particular between 0.3 mm and 0.35 mm, and the thread density of the MD threads is more than 37%, in particular between 37% and 45%. The invention additionally relates to a corresponding machine and method for producing a tissue web.