Stretchable Sheet Gear Drawing With Optimized Tooth Pitch
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Solution Overview
Problem
The existing gear drawing method for producing stretchable sheets can result in uneven stretchability due to the interaction between the gear rolls' teeth and embossed sections on the raw sheet, leading to local irregularities in stretchability.
Innovation Solution
A method and apparatus where the arrangement pitch of the gear rolls' teeth is set greater than the formation pitch of the embossed sections but less than twice that pitch, ensuring even development of stretchability by avoiding direct contact between the embossed sections and the teeth, and arranging the embossed sections in a lattice pattern orthogonal to the drawing direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If gear drawing is performed on a raw sheet with embossed sections, then stretchability is developed in the raw sheet, but drawing irregularity occurs and stretchability becomes uneven
Solution Approach 1:
The patent applies parameter changes by establishing a specific mathematical relationship between the arrangement pitch of gear roll teeth (Pt) and the formation pitch of embossed sections (Pe), defined by the inequality Pe < Pt < 2Pe. This parameter optimization ensures that the gear teeth do not directly contact the embossed sections during drawing, preventing drawing irregularity while maintaining effective stretchability development in the raw sheet.
2Productivity
If the arrangement pitch of gear roll teeth is too small, then drawing effectiveness is reduced, but if it is too large, then drawing irregularity increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the arrangement pitch parameter within a specific range relative to the embossed section pitch. The inequality Pe < Pt < 2Pe defines the optimal parameter window that balances drawing effectiveness (sufficient tooth density) with drawing uniformity (avoiding direct tooth-emboss contact), thereby maximizing productivity while maintaining manufacturing precision.
3Strength
If embossed sections are present on the raw sheet, then fiber fallout is prevented, but stretchability development becomes uneven
Solution Approach 1:
The patent maintains the beneficial fiber retention function of embossed sections while eliminating their negative impact on stretchability uniformity through parameter optimization. By setting the gear tooth arrangement pitch within Pe < Pt < 2Pe, the drawing process avoids direct contact with embossed sections, allowing uniform stretchability development while preserving the fiber fallout prevention function.
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 reduces damage to the sheet and ensures consistent stretchability across the produced stretchable sheet, minimizing irregularities and improving the integrity of the final product.
Implementation Method 1
the raw sheet is deformed into a shape bent at three points by the teeth of the upper and lower gear rolls that mesh with one another so as to draw the raw sheet in the direction of rotation of the gear rolls
Implementation Method 2
an emboss process is performed on the raw sheet. In other words, substantially an entire surface of the raw sheet is provided with an embossed section that is formed in a recessed manner
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3D
AI summary
A method of producing a stretchable sheet includes preparing a pair of gear rolls each having a plurality of teeth arranged on a circumference thereof, the gear rolls being rotatable about respective axes of rotation with the teeth meshing each other; and drawing a raw sheet in a drawing direction using the teeth by passing the raw sheet through a gap between the pair of gear rolls, the raw sheet containing a plurality of types of fibers, the drawing direction being either a direction of rotation of the gear roll or a direction parallel to the axes of rotation; the raw sheet having a plurality of recessed sections formed by pressing, the recessed sections being formed collinearly at least along the drawing direction at a predetermined formation pitch in the drawing direction; with respect to each gear roll of the pair of gear rolls, an arrangement pitch of the teeth in the drawing direction is greater than the formation pitch and smaller than twice as long as the formation pitch.