Nonwoven Stretchable Sheet Drawing with Pre-Tensioned Gear Rolls
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Solution Overview
Problem
The existing gear drawing method for producing stretchable sheets from nonwoven fabrics faces limitations in increasing the drawing amount due to gear backlash, which can lead to fabric breakage and reduced stretchability.
Innovation Solution
A two-step drawing process involving initial tension application in the longitudinal direction followed by passing the fabric through engaged gear rolls with teeth, allowing for a higher drawing amount and increased stretchability without fabric breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the engagement depth of the gear roll teeth is increased to increase the drawing amount, then the stretchability of the nonwoven fabric is improved, but the relative position fluctuation of the teeth increases due to gear backlash, causing the teeth to contact each other and potentially breaking the fabric
Solution Approach 1:
The nonwoven fabric is preliminarily drawn by applying tension in the longitudinal direction before entering the gear rolls. This preliminary drawing action prepares the fabric structure to accommodate the subsequent gear drawing process, allowing for greater total drawing amount without fabric breakage by distributing the deformation stress across two separate stages
2Productivity
If a single gear drawing process is used to increase the drawing amount, then the stretchability is improved, but the gear backlash causes tooth contact and fabric breakage
Solution Approach 1:
The drawing process is segmented into two distinct steps: a first drawing step using tension application and a second drawing step using gear rolls. This segmentation allows each step to operate within optimal parameters, with the first step preparing the fabric and the second step providing controlled additional drawing, thereby achieving high total drawing amount while maintaining precise tooth position control throughout the 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 method effectively increases the drawing amount of the nonwoven fabric, resulting in a stretchable sheet with enhanced stretchability and reduced risk of fabric breakage during the drawing process.
Implementation Method 1
a first drawing step of drawing the nonwoven fabric in the longitudinal direction by applying a tension in the longitudinal direction
Implementation Method 2
the nonwoven fabric is deformed into a shape bent at three points by the teeth 41t and 43t of the upper and lower gear rolls
Data Source
AI summary
A stretchable sheet having a large stretch amount is produced by increasing a drawing amount given to the nonwoven fabric. A method for producing the stretchable sheet from a nonwoven fabric containing a plurality of types of fibers, that is the nonwoven fabric having a longitudinal direction, a width direction and a thickness direction. The method includes a first drawing step of drawing the nonwoven fabric in the longitudinal direction by applying a tension in the longitudinal direction of the nonwoven fabric, and a second drawing step of drawing, in the longitudinal direction, the nonwoven fabric that has been drawn in the first drawing step with a plurality of teeth formed on outer circumferential faces of each of a pair of gear rolls, the drawing being performed by passing the nonwoven fabric through a gap between the gear rolls that rotate while the teeth are being engaged with one another.