Nonwoven Web Transfer via Pneumatic Air Currents
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Solution Overview
Problem
In wet-laid nonwoven production, existing methods face challenges with web threading at the start of production and after interruptions, particularly due to the need for high production speeds and safety guidelines, which complicate the transfer of nonwoven webs between machine components without causing web breaks or operational disruptions.
Innovation Solution
A device with a temporarily closed train system is introduced, utilizing air currents and compressed air to detach and transfer the nonwoven web from the screening device to subsequent treatment units, allowing for controlled and stable web threading, even at high speeds, by cutting a tail threading belt and using it as a temporarily closed train to guide the web to the next unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If free pull transfer is used to remove the web from the screen, then the web can be transferred to the following unit, but the web must have considerable initial wet strength to withstand removal without tearing and is subjected to considerable tensile stresses
Solution Approach 1:
A pick-up felt is introduced as an intermediary element between the screen and the following unit. The felt temporarily holds the web during transfer, reducing direct tensile stresses on the web itself. The felt acts as a mediator that absorbs and distributes the mechanical stress, allowing web transfer without requiring high initial wet strength from the web.
Solution Approach 2:
The mechanical free pull transfer system is replaced with a pneumatic system. Compressed air is used to lift and transfer the web from the screen to the pick-up felt, eliminating the need for mechanical tensioning and reducing tensile stresses on the web during the transfer process.
2Strength
If closed removal using a pick-up felt is used, then the web can be transferred with reduced tensile stresses, but good adhesion between the web and the felt is required which demands sufficient moisture content in the felt and paper-like character of the nonwoven web
Solution Approach 1:
The adhesion mechanism is changed from moisture-based to mechanical interlocking. The pick-up felt is designed with a specific surface structure that mechanically interlocks with the nonwoven web fibers, eliminating the need for moisture-based adhesion. This allows transfer of webs with various fiber compositions without requiring paper-like characteristics.
Solution Approach 2:
The pick-up felt is designed with locally optimized properties - a specific surface structure in the contact area that enhances mechanical interlocking with the web. This localized structural modification provides universal adhesion capability across different web types without requiring global changes to the felt or web properties.
3Device complexity
If the nonwoven web is transferred directly from the wire to a dryer surface, then intermediate elements are eliminated, but this solution is not suitable if the nonwoven web is to be consolidated before drying by means of hydroentanglement or binding agent application
Solution Approach 1:
The pick-up felt system is designed as a universal interface that can accommodate multiple downstream processing options. The same pick-up felt mechanism supports transfer to hydroentanglement devices, binding agent application units, or direct dryer surfaces, making the system versatile for different consolidation methods without requiring structural changes.
4Productivity
If free drafts are provided between treatment units, then each unit can be equipped with different sieve belts for economical and energy-optimized operation, but web threading at the start of production and after interruptions becomes complicated
Solution Approach 1:
A web threading device is installed at the beginning of the production line that performs preliminary web preparation and guidance actions. This device automatically threads the web through all treatment units at the start of production and after interruptions, eliminating manual intervention and ensuring consistent web positioning before high-speed production begins.
Solution Approach 2:
The web threading device is designed to automatically perform the threading operation without external intervention. The system self-regulates web tension, positioning, and guidance through the treatment units, enabling automated operation that maintains high production speeds while simplifying the threading process.
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 solution enables efficient and stable web transfer at high production speeds, preventing web breaks and allowing for automated operation, thus improving the reliability and efficiency of web guidance between machine components.
Implementation Method 1
A tail threading belt of the fleece web is caught by the temporarily closed train and is cut from the running web on the outlet side of a screen belt of the screening device. This strip is transferred to the following treatment unit with air currents from the temporarily closed train.
Implementation Method 2
A tail threading belt of the fleece web is caught by the temporarily closed train and is cut from the running web on the outlet side of a screen belt of the screening device
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
A method for producing wet-laid nonwovens, in which an aqueous suspension containing fibers is deposited on a screen and dewatered by suction boxes (12) under the screen to form a sheet of nonwoven web (10), which is removed from the screen and guided to at least one subsequent treatment unit before the nonwoven web can be wound up, and transferring the nonwoven web from the screen to the at least one subsequent treatment unit and/or transferring the nonwoven web at interfaces (8, 9) between treatment units at the start of production and/or after a production interruption using a web guide, wherein the web guide is provided by a temporarily closed section of a free section between the screen and the at least one subsequent treatment unit and/or by a free section at an interface between treatment units, and the temporarily closed section is generated by air currents.which remove an end feed belt (14) as part of the running nonwoven web by suction, attach it to a transport device (19) by generating negative pressure and convey it to the respective subsequent treatment unit.