Apparatus and method for bonding layers comprising fibers to form a non-woven web
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Solution Overview
Problem
The reproducibility of non-woven web production is compromised when bonding layers of short and long fibers due to elastic properties of carded long fiber layers, leading to deformations and defects, particularly when a light and wet wood fiber layer is applied to a layer of long fibers.
Innovation Solution
An apparatus with a pre-bonding unit comprising spaced compactors and a water-jet bonding device is used to compact and bond the layers directly behind the transfer point, reducing the distance between the belts to less than the sum of their thicknesses, thereby avoiding pre-compaction and minimizing recovery of the long fiber layer, ensuring consistent bonding without detachment of short fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the two layers are pre-compacted at the transfer point using a deflection roller, then the layers are compacted before bonding, but this causes recovery effects in the long fiber layer leading to deformations and defects
Solution Approach 1:
The patent applies preliminary action by performing the bonding operation before compaction. The bonding device is positioned to bond the short fiber layer to the long fiber layer at the transfer point before the layers enter the compaction zone between the belts. This sequence prevents the long fiber layer from undergoing compaction-induced deformation that would compromise bonding quality and production reproducibility.
2Manufacturing precision
If the distance between the first and second belts is greater than the sum of the thicknesses of the two layers, then there is no compaction in the bonding region, but this reduces bonding effectiveness
Solution Approach 1:
The patent applies local quality by creating a localized compaction zone between the first and second belts that is spatially separated from the bonding region. The belts are configured to compact the layers in a specific area while maintaining a larger distance in the bonding region, ensuring that compaction forces are applied only where needed without interfering with the bonding process.
3Strength
If the long fiber layer is compacted, then the layers are bonded together, but the elastic properties of the long fiber layer cause recovery effects after compaction
Solution Approach 1:
The patent performs bonding as a preliminary action before compaction. By bonding the layers at the transfer point before they enter the compaction zone, the long fiber layer is secured to the short fiber layer while still in its uncompressed state, preventing subsequent elastic recovery and shape deformation that would occur if compaction were performed first.
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 approach enhances the reproducibility of non-woven web production by preventing deformations and defects, ensuring strong and defect-free bonding of the layers while reducing production costs and maintaining the integrity of the short fibers.
Implementation Method 1
The bonding device is configured to bond together the first layer with the second layer by twirling the long fibers and the short fibers
Implementation Method 2
reducing the distance between the belts to less than the sum of their thicknesses, thereby avoiding pre-compaction
Data Source
AI summary
An apparatus for bonding a first layer having short fibers with a second layer having long fibers into a non-woven web. The apparatus includes a first circulating belt on which the second layer is depositable and displacable, a second circulating belt via which the first layer is transferable at a transition point to the second layer, a pre-bonding unit arranged directly behind the transition point, and a bonding device. The pre-bonding unit has compactors which are spaced apart from one another. The compactors act in one region on the first or second circulating belt. The bonding device is arranged between the compactors and bonds together the first and second layers. The compactors and the bonding device are integrated into the apparatus to together be in an operating state when the first layer is transferred using the second circulating belt.