Spunbond Cooling Chamber Air Extraction for Edge Defects
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Solution Overview
Problem
Existing spunbond apparatuses produce nonwovens with inhomogeneities and defects at the edges due to instability in filament guidance, leading to irregular deposits, yarn breakage, and adhesions, which result in unwanted holes during the transfer process.
Innovation Solution
The apparatus features a cooling chamber with air extraction at the longitudinal side walls parallel to the machine direction, influencing the cooling air flow to maintain uniform filament guidance and prevent cross-sectional enlargement, ensuring homogeneous edge regions and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is supplied through the long transverse walls of the cooling chamber, then the cooling chamber can be effectively cooled, but the filament guidance becomes unstable at the edges causing inhomogeneities and defects
Solution Approach 1:
The cooling chamber side walls are segmented into different functional zones: long transverse walls for cooling air supply and short longitudinal walls for air extraction. This segmentation allows independent optimization of cooling efficiency and filament guidance stability at different locations.
Solution Approach 2:
Air extraction openings are provided in the short longitudinal walls to extract excess cooling air and stabilize the airflow pattern. This extraction mechanism removes disruptive air currents that cause filament instability at the edges while maintaining effective cooling through the transverse walls.
2Productivity
If high production speeds and throughputs are used, then productivity increases, but filament guidance instability worsens leading to more defects and yarn breakage
Solution Approach 1:
The air extraction system acts as a feedback mechanism that continuously removes excess cooling air and stabilizes the airflow pattern in real-time. This active control allows the system to maintain filament guidance stability even at high production speeds where inertial effects would otherwise cause instability.
3Temperature
If the cooling chamber dimensions are elongated in the transverse direction, then cooling efficiency improves, but edge region defects increase due to filament instability
Solution Approach 1:
The cooling chamber exhibits asymmetric functionality in its wall design: the long transverse walls serve primarily for cooling air supply while the short longitudinal walls serve for air extraction. This asymmetric functional distribution allows the chamber to be elongated in the transverse direction for improved cooling efficiency while using the longitudinal walls to extract disruptive air currents and maintain edge region uniformity.
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
This configuration results in a stable, compact, and uniform edge region with minimal defects, suitable for high throughputs and speeds, achieving defect-free nonwovens with uniform weight distribution across the width, even at high production rates.
Implementation Method 1
a cooling chamber directly beneath the spinneret for receiving the filaments from the spinneret and cooling the spun filaments with cooling air
Implementation Method 2
cooling the spun filaments with cooling air
Data Source
AI summary
Spunbonded nonwoven is made from continuous thermoplastic filaments emitted downwardly by a spinneret in a filament direction. A cooling chamber directly beneath the spinneret receives the filaments from the spinneret and cools the spun filaments with cooling air and has relative to a longitudinally extending machine direction a pair of longitudinal sides extending parallel to the machine direction and a pair of transverse sides extending substantially perpendicular to the machine direction between the longitudinal sides. Respective air-supply manifolds on the transverse sides feed cooling air therefrom into the cooling chamber. The cooling air is extracted from the cooling chamber at the longitudinal sides. A stretcher directly beneath the cooling chamber receives and elongates the cooled filaments, and a device deposits the stretched filaments as a band and conveys the band off in the machine direction.