Suction Device Segmented Surface for Fiber Dispersion
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Solution Overview
Problem
Suction devices in papermaking machines, such as moulding boxes in TAD machines, cause disturbances downstream due to the accumulation and clogging of fines and fibers, leading to process disruptions.
Innovation Solution
A suction device with a fabric-facing surface featuring planar surfaces and ribs that create channels for underpressure, including a final channel with a smaller cross-sectional area and flow restrictor, designed to manage airflow and prevent fiber accumulation by ensuring fines and fibers are dewatered and dispersed, reducing the likelihood of large lumps forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a suction device is used to draw fibrous web through permeable fabric, then the fabric pattern is imprinted into the web and drying efficiency is improved, but fines and fibers accumulate and clog the suction device causing downstream disturbances
Solution Approach 1:
The suction device surface is segmented into multiple solid elements (ribs) separated by channels, creating a structured pattern that controls fiber distribution and prevents accumulation while maintaining effective suction for drying and imprinting
Solution Approach 2:
Different regions of the suction device have different geometries - the first part has planar surfaces for contact and imprinting, while the second part has non-planar surfaces spaced from the fabric path to allow air flow and prevent clogging, with each region optimized for its specific function
2Manufacturing precision
If the suction device draws fabric and web together for imprinting, then pattern transfer is achieved, but large lumps of fibers form and cause breaks
Solution Approach 1:
The suction surface is divided into discrete solid elements that create controlled channels between them, distributing fibers evenly across the surface and preventing localized accumulation that would form harmful lumps
Solution Approach 2:
The suction device uses the natural flow of air and fibers through the channel pattern to convert potential clogging into beneficial fiber distribution, where the channels guide fibers away from accumulation zones and toward areas where they can be evenly dispersed in the dried web
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
Significantly reduces the occurrence of breaks and defects in the papermaking process by ensuring that fines and fibers are dispersed and do not clog the suction device, maintaining process stability and efficiency.
Implementation Method 1
the suction device can act on the permeable fabric through the channels and draw the permeable fabric by suction effect towards the fabric-facing surface
Implementation Method 2
an underpressure can be generated in the area between the permeable fabric and the surface of the final solid element
Data Source
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AI summary
The invention relates to a suction device (15) for use in a papermaking machine and being suitable for acting on a wet fibrous web through a permeable fabric (4, 6), e.g. a through- air-drying (TAD)-fabric. The suction device has a fabric-facing surface (18) formed by a plurality of end surfaces of solid elements (21, 22). Channels (24, 25) are defined between the solid elements. The end surface of the final solid element (22) does not lie in the same plane as the end surfaces of the previous solid elements (21). Thereby, a gap A is formed between the fabric (4, 6) and the final solid element (22). This allows air to flow through the gap and into a final channel (25). The air flow will then catch fines, small fibers and water droplets and draw them into the final channel (25) thereby counteracting a build-up of large lumps of fines and fibers.