Method and machine for spreading a fabric-type textile sheet
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Solution Overview
Problem
Existing methods for spreading and homogenizing the thickness of fibrous sheets result in significant thickness variations, particularly at the edges, leading to unreliable and robust composite parts due to the interlacing of warp and weft yarns, which causes shrinkage and uneven pressure distribution during the weaving process.
Innovation Solution
A method and machine that utilize rotary rollers with adjustable pressure generators, where one roller is flexible and the other is rigid, allowing for axial oscillation and localized pressure adjustments to ensure uniform pressure across the sheet, reducing thickness variability by modulating pressure between the center and edges, and heating the sheet during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spreading methods are used on fabrics with significant initial thickness variations, then the fabric can be processed, but the thickness variability remains high and cannot be adequately homogenized
Solution Approach 1:
The patent applies localized pressure through independently controllable pressure zones along the roller axis. Each zone can exert different pressure levels tailored to the local thickness characteristics of the fabric, allowing precise correction of thickness variations at different positions without affecting other areas.
Solution Approach 2:
The patent employs axially oscillating rollers that dynamically adjust pressure distribution during the spreading process. The oscillation enables the rollers to adapt to varying fabric thickness in real-time, transforming a static pressure application into a dynamic, adaptive process that responds to local thickness conditions.
2Manufacturing precision
If high tension is applied to spread the fabric, then spreading effectiveness improves, but roller flexure increases preventing parallelism and homogeneous pressure distribution
Solution Approach 1:
The patent divides the pressure application into multiple independent localized zones along the roller axis. This segmentation allows each zone to be controlled independently, maintaining pressure homogeneity within each zone while accommodating overall fabric thickness variations, thus preventing roller flexure-induced non-uniformity.
Solution Approach 2:
The patent utilizes axial oscillation of the rollers to prevent fabric adhesion and maintain consistent pressure distribution. The vibratory motion counteracts the flexure effects by continuously adjusting the contact pressure, ensuring roller parallelism is maintained even under high tension conditions.
3Shape
If roller diameter is increased to reduce flexure, then roller parallelism improves, but inertia increases significantly requiring more energy
Solution Approach 1:
The patent employs axial oscillation of the rollers to achieve the benefits of larger diameter rollers (reduced flexure) without actually increasing the roller diameter. The dynamic oscillation compensates for flexure effects, allowing the use of smaller, lighter rollers that consume less energy while maintaining parallelism.
Solution Approach 2:
The patent changes the operational parameters of the rollers by introducing axial oscillation motion. This parameter change allows the system to achieve improved roller parallelism and pressure distribution without modifying the physical dimensions of the rollers, thereby avoiding the energy penalty associated with larger, more inertial rollers.
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 achieves fabrics with low thickness variability, enabling the production of composite parts with controlled geometry and improved robustness, maintaining uniform thickness across large widths and reducing thickness standard deviation to less than 90 μm, depending on the basis weight range.
Implementation Method 1
heating the sheet during processing
Implementation Method 2
axial oscillation and opposed in phase
Data Source
AI summary
A method for spreading a textile sheet where the sheet is caused to run between at least two rotary rollers, the axes of which extend parallel to each other and substantially perpendicular to the running direction of sheet. The sheet under pressure is caused to pass between at least one pressure generator of the rollers driven into axial oscillation and in phase opposition. At least one pressure generator of the rollers has adjustable pressure values along the generator in order to spread the sheet with a low thickness variability.