Ultrasonic Welded Braid Support for Hollow Fiber Membranes
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Solution Overview
Problem
Existing methods for manufacturing hollow fiber membranes often result in supports that are either too dense or lack sufficient structural stability, particularly when subjected to vigorous agitation in membrane bioreactors, leading to potential fiber breakage and limitations in dope coating.
Innovation Solution
A method and apparatus using a tubular support forming device and ultrasonic welding to arrange and sonically weld filaments into a tubular structure that crosses both circumferentially and radially, creating a support that can be self-supporting or manipulated into a tubular shape with enhanced stability through acoustic energy-induced welding at intersections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a dense braid structure is used to provide structural stability, then the support strength is improved, but the dope coating capability deteriorates due to insufficient permeability
Solution Approach 1:
The braid structure is designed with controlled porosity to allow dope penetration while maintaining structural strength. The interstices between braided filaments provide pathways for dope coating, resolving the contradiction between density for strength and porosity for coating capability.
2Device complexity
If fewer filaments are used in the braid, then the manufacturing complexity is reduced, but the dimensional stability deteriorates leading to fiber breakage
Solution Approach 1:
Ultrasonic welding is applied preliminarily to join filaments at intersection points before the membrane formation process. This preliminary action creates stable anchor points that maintain dimensional stability even with fewer filaments, preventing fiber breakage during subsequent handling and operation.
3Strength
If ultrasonic welding is applied to join filaments, then the structural stability is improved, but the manufacturing complexity increases
Solution Approach 1:
Traditional mechanical joining methods are replaced with ultrasonic welding, which uses acoustic energy to fuse filaments at intersection points. This substitution provides more reliable structural stability through molecular-level bonding while maintaining manufacturing efficiency through automated ultrasonic welding systems.
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 provides improved dimensional stability and strength for hollow fiber membranes, reducing the incidence of fiber breakage and allowing for effective dope coating, even with fewer filaments, thus enhancing their performance in microfiltration and ultrafiltration processes.
Implementation Method 1
an ultrasonic welding device. The method comprises the steps of arranging a set of filaments into a tubular supporting structure and sonically welding the filaments together at points of intersection between the filaments
Data Source
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AI summary
A tubular support for use with a hollow fiber membrane is made with an apparatus that comprises a forming machine and an ultrasonic welding machine. The apparatus may also include a coating nozzle for depositing a dope on the support, in operation, filaments are formed into a tubular structure in which the filaments cross each other in radial and circumferential directions, for example a braid. The filaments are ultrasonically welded together at intersections between them. The support is combined with a polymeric membrane wall to form a hollow fiber membrane.