Stretchable Wearable Sheet Weakening for Continuous Ultrasonic Welding
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Solution Overview
Problem
Existing methods for producing wearable articles with partially weakened stretchability face challenges in continuous processing due to high temperatures caused by ultrasonic welding, leading to unintended melting of the stretchable sheet beyond the joint areas.
Innovation Solution
A production method involving ultrasonic welding of sheet bodies and an elastic film, followed by a weakening step to form notches or additional joints, and an attachment step to integrate an absorbent body, ensuring the temperature of the welding equipment does not rise excessively, allowing continuous processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultrasonic welding is performed using a large number of pressure convex portions at high density to form a region with high area ratio of joints, then the stretchability of the stretchable sheet is weakened, but the temperature of the anvil roll or ultrasonic horn becomes too high causing the non-joint regions to melt
Solution Approach 1:
The patent divides the attachment location into multiple discrete pressure convex portions arranged in a matrix pattern, segmenting the welding area into manageable units. This segmentation allows heat to be distributed across multiple points rather than concentrated in one large area, preventing excessive temperature buildup while still achieving the desired weakening effect through cumulative joint area
Solution Approach 2:
The patent applies partial action by using a controlled number of pressure convex portions with specific spacing, rather than excessive welding density. The area ratio of joints is optimized to provide sufficient weakening without requiring such high density that would generate excessive heat and cause melting of non-joint regions
2Manufacturing precision
If ultrasonic welding is performed at high density to weaken stretchability, then the area ratio of joints increases, but continuous processing becomes difficult due to melting
Solution Approach 1:
The patent uses a moderate density of pressure convex portions that provides sufficient joint area ratio for weakening stretchability without exceeding the threshold that would cause melting. This partial action approach maintains continuous processing capability while achieving the desired mechanical property modification
Solution Approach 2:
The patent optimizes parameters including the number, size, and spacing of pressure convex portions to achieve the desired joint area ratio. By carefully controlling these parameters, the process maintains temperatures within safe limits for continuous operation while still achieving adequate weakening of the elastic film
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 method enables the continuous production of stretchable sheets with partially weakened stretchability, preventing unintended melting and improving processing efficiency while maintaining design flexibility.
Implementation Method 1
a welding step of ultrasonically welding a pair of sheet bodies and an elastic film to each other at a plurality of joints separated from each other in a predetermined transport direction
Data Source
AI summary
A wearable article production method for a stretchable sheet having partially weakened stretchability includes a welding step of ultrasonically welding two sheet bodies and an elastic film to each other at plural joints separated from each other in a predetermined transport direction in a region including a predetermined attachment location by transporting a sheet laminate formed by sandwiching the elastic film in an elongated state between the two sheet bodies in the transport direction so that the sheet laminate passes between an anvil roll and an ultrasonic horn to form a stretchable sheet; a weakening step of forming weakened regions, where stretchability of the elastic film is weakened, at least at a part of the attachment location in the stretchable sheet after the welding step; and an attachment step of attaching an absorbent main body to the attachment location so that the absorbent main body overlaps the weakened regions.