Air Guiding Elements for Uniform Spunbond Nonwoven Fiber Orientation
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Solution Overview
Problem
Existing devices and methods for producing spunbond nonwovens struggle to achieve uniform strength distribution in both the machine direction (MD) and cross-direction (CD) due to limitations in influencing fiber formation, resulting in an MD/CD strength ratio greater than 1.5, which is not suitable for technical applications requiring even strength.
Innovation Solution
A device and method that utilize air guiding elements and secondary air flows to influence the fiber orientation across the entire width of the depositing belt, generating transverse flows to evenly distribute filaments, with adjustable air guiding elements and secondary air inlet slots to control the fiber flow and achieve uniform deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional guide sections with cross-sectional changes are used to influence fiber flow, then fiber orientation in the flow direction can be improved, but fiber distribution transverse to the flow direction remains uneven
Solution Approach 1:
The invention introduces air inlet slots that supply secondary air flows perpendicular to the primary fiber flow direction, adding a transverse dimension to fiber flow control. This enables influence on fiber distribution across the width of the fleece, not just in the machine direction, thereby achieving more uniform fiber orientation in both MD and CD directions
2Manufacturing precision
If multiple guide sections merging into one another are used, then fiber stream guidance is improved, but the ability to influence fiber flow transversely to the deposit belt is limited
Solution Approach 1:
The invention divides the air supply system into multiple segmented air inlet slots distributed across the width of the deposit belt. Each slot can supply secondary air flows independently, allowing separate control of fiber distribution in different transverse zones. This segmented approach enables versatile transverse flow influence while maintaining effective fiber stream guidance through the guide sections
3Adaptability or versatility
If suction devices divided into zones are assigned to the deposit belt, then filament pickup intensity can be varied, but web density becomes uneven
Solution Approach 1:
The invention applies preliminary action by supplying secondary air flows through air inlet slots before the filaments reach the deposit belt. This pre-influence on fiber flow direction and distribution ensures uniform fiber arrangement during deposition, preventing the need for post-deposition density adjustment through varied suction intensities, thereby maintaining even web 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
The solution enables the production of spunbond nonwovens with a more even MD/CD strength ratio, typically between 1.0 and 1.5, suitable for technical applications like filter substrates and geotextiles, by ensuring uniform fiber distribution and orientation.
Implementation Method 1
at least one partial flow of secondary air is fed to the fiber stream laterally next to the filament curtain at an inflow angle transverse to the deposit belt
Implementation Method 2
the curtain of filaments is pulled off by means of a draw-off nozzle and then guided as a fiber stream in the direction of a deposit belt
Data Source
AI summary
Apparatus comprises a discharge device (1); a depositing belt arranged below the discharge device; and many guiding devices arranged between the discharge device and the deposit belt. The guiding devices form many inter-connected guiding lines in a pair-wise manner, to guide a filament curtain formed by the filaments. The guiding devices comprise many air inlet slots arranged below the discharge device, to supply a secondary air. At least one of the air inlet slots is associated with many air guiding elements arranged on one of the guiding devices. An independent claim is also included for guiding and depositing the synthetic filaments to form the fleece, comprising: cooling many extruded filaments, stripping and stretching the extruded filaments as a filament curtain by a generated primary air flow; directing the filament curtain with the primary air stream as a fiber stream in the direction of the depositing belt by a guiding path; and supplying many partial streams of secondary air to the fiber stream for influencing a fiber formation in the fleece. At least one of the partial streams of the secondary air is supplied to the side adjacent to the filament curtain at an inflow angle of the fiber stream across the depositing belt.