Spunbond Apparatus Diffusor Suction for Homogeneous Filament Deposition
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Solution Overview
Problem
Existing spunbond apparatuses face challenges in achieving high filament speeds and low titers while maintaining the quality of nonwoven webs, particularly at high production rates, due to issues with homogeneity and strength of filament deposition.
Innovation Solution
The apparatus includes a spinneret, cooler, stretcher, and a depositing device with a diffusor and suction system, where secondary air-inlet gaps are oriented at specific angles and the suction device has an unobstructed extraction region wider than the diffusor outlet, ensuring efficient air flow and deposition of continuous filaments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high filament speeds and high throughputs are used, then productivity is improved, but the quality of filament deposition and nonwoven web homogeneity deteriorates
Solution Approach 1:
The patent employs a pneumatic system with a diffusor and suction device to control air flow dynamics. The diffusor expands the air flow cross-section to reduce velocity and increase mixing, while the suction device creates controlled air currents that guide filaments onto the web. This pneumatic control enables high filament speeds to be maintained while ensuring homogeneous deposition through optimized air flow patterns.
Solution Approach 2:
The patent changes physical parameters of the air flow system by introducing a diffusor that modifies velocity, pressure, and flow direction. The suction device adjusts air flow rates and patterns to match high filament speeds. These parameter adjustments allow the system to operate at high productivity levels while maintaining deposition quality through optimized aerodynamic conditions.
2Productivity
If high filament speeds are used, then productivity is improved, but the strength and quality of nonwoven webs deteriorate
Solution Approach 1:
The pneumatic system with the diffusor and suction device creates controlled air currents that ensure proper filament placement and web consolidation at high speeds. The air flow dynamics regulate filament tension and deposition patterns, maintaining web strength even when filament speed is increased for higher productivity.
Solution Approach 2:
The suction device acts as a feedback mechanism that continuously adjusts air flow based on deposition conditions. This feedback control ensures that filament placement remains optimal at high speeds, preventing web defects and maintaining strength by dynamically adapting air flow to match filament velocity and deposition requirements.
3Productivity
If low titer continuous filaments are used, then productivity is improved, but deposition quality and web homogeneity deteriorate
Solution Approach 1:
The diffusor and suction device create optimized air flow patterns that compensate for the lower density and different deposition characteristics of low titer filaments. The pneumatic system adjusts air flow velocity and distribution to ensure homogeneous deposition of low titer filaments at high speeds, maintaining deposition quality despite the reduced filament density.
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 allows for high-quality, homogeneous filament deposition and nonwoven web production even at high speeds and production rates, with the ability to achieve high filament speeds and low titers without compromising quality.
Implementation Method 1
at least one cooler for cooling the filaments
Implementation Method 2
a suction device for extracting air through the foraminous belt
Data Source
AI summary
An apparatus for making spunbond from continuous thermoplastic filaments has a spinneret for spinning the continuous filaments and advancing them in a filament-travel direction, a cooler for cooling the filaments, a stretcher for stretching the filaments, a depositing device including a foraminous belt extending in a machine direction transverse to the filament-travel direction for deposition of the filaments as a nonwoven web and conveyance away from the stretcher, a diffusor between the stretcher and the foraminous belt so that filaments and primary air from the stretcher enter into the diffusor, and a suction device for extracting air through the foraminous belt at an unobstructed extraction region underneath the diffusor outlet and having a width b in a machine direction that is greater than a width B of the diffusor outlet. The diffusor forms upstream and downstream secondary air-inlet gaps at opposite ends through which secondary air is aspirated into the diffusor.