Method and device for manufacturing a spunbonding fabric made of filaments and spun fabric
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Solution Overview
Problem
Existing spunbond production methods result in non-isotropic strengths between the machine direction (MD) and cross-machine direction (CD), with higher longitudinal strengths compared to transverse strengths, and struggle to achieve homogeneous filament deposition.
Innovation Solution
A method involving the use of a spinning device, cooling device, and stretching device with primary and secondary air flows, where the secondary air ratio is greater than 4.5, and a diffuser with asymmetrical air inlet gaps and diverging walls to control air flow and filament deposition, ensuring isotropic strengths and homogeneous laydown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional stretching and diffuser configuration is used, then production efficiency is maintained, but the spunbond exhibits non-isotropic strength with higher longitudinal strength compared to transverse strength
Solution Approach 1:
The patent applies asymmetry by configuring the diffuser with non-uniform air inlet gaps across its width. Specifically, the air inlet gaps are smaller in the central region and larger in the edge regions. This asymmetric configuration creates different air flow patterns that result in more uniform filament deposition and isotropic strength distribution (MD/CD ratio between 0.8-1.2) in the spunbond product.
Solution Approach 2:
The patent implements local quality by varying the air inlet gap dimensions at different locations across the diffuser width. The central region has smaller gaps while edge regions have larger gaps, creating location-specific air flow characteristics that collectively achieve homogeneous filament distribution and isotropic mechanical properties throughout the entire spunbond web.
2Manufacturing precision
If conventional air flow configuration is used, then processing simplicity is maintained, but homogeneous filament deposition cannot be achieved
Solution Approach 1:
The patent applies parameter changes by modifying the air inlet gap dimensions of the diffuser. The gaps are designed with specific dimensional variations (smaller in center, larger at edges) to control air flow velocity and pressure distribution, thereby achieving homogeneous filament deposition patterns that result in isotropic spunbond properties.
3Strength
If secondary air ratio is increased to improve transverse strength, then isotropy is enhanced, but air flow control complexity increases
Solution Approach 1:
The patent implements self-service by designing the diffuser structure itself to inherently control the air flow distribution. The asymmetric air inlet gaps automatically create the necessary flow patterns without requiring external control mechanisms, sensors, or active regulation systems. The geometry of the diffuser does the work of balancing the air flow to achieve isotropic strength.
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
The method achieves balanced tensile strengths in both MD and CD directions, with a ratio of 0.8 to 1.2, and ensures a uniform and homogeneous filament deposition, enhancing the opacity and coverage of spunbonds while maintaining high transverse strength.
Implementation Method 1
the filaments are passed through a stretching device with primary air
Implementation Method 2
the filaments are cooled
Implementation Method 3
secondary air being introduced into the diffuser with a secondary air volume flow
Implementation Method 4
the filaments are guided through a diffuser
Implementation Method 5
a cooling device with at least one cooling chamber is expediently provided, in which the filaments are supplied with cooling air
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Process for the production of a spunbonded fabric from filaments, wherein the filaments are spun by means of at least one spinning device, are then cooled and then passed through a stretching device with primary air. The primary air exits the stretching device with a primary air volume flow VP, with the filaments being guided through a diffuser downstream of the stretching device. Secondary air with a secondary air volume flow Vs is introduced into the diffuser between the stretching device and the diffuser. The filaments are deposited on a depositing device connected to the diffuser. The ratio of the primary air volume flow VP to the secondary air volume flow Vs is more than 4.5, preferably more than 5 and very preferably more than 5.5.