Elastic Member Sheet Joint Geometry for Welding Defect Prevention
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Solution Overview
Problem
Welding defects occur when sheet joined portions with different shapes are used in elastic members for disposable wearing articles, leading to weak bonding between sheet layers and potential equipment wear or breakage.
Innovation Solution
The elastic member features sheet joined portions with a reference bonding diameter of 0.25 to 0.5 mm and a circumference length 1 to 15 times that of a circle's circumference, formed using nonwoven fabrics with specific fineness and basis weight, to ensure robust bonding and prevent welding defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sheet joined portions with different shapes are used to improve surface fitting and elasticity, then the adaptability and surface fitting are improved, but welding defects occur and bonding strength decreases
Solution Approach 1:
The patent applies local quality by providing different types of sheet joined portions (first type with smaller reference bonding diameter, second type with larger reference bonding diameter) at different locations within the stretchable region. This allows different areas to have different bonding characteristics suited for their specific functional requirements while maintaining overall welding reliability through controlled geometric parameters
Solution Approach 2:
The patent controls the reference bonding diameter and circumference length of sheet joined portions within specific ranges. By changing these geometric parameters while keeping them within controlled limits, the patent achieves both good surface fitting through shape variation and reliable welding by preventing excessive parameter differences that would cause welding defects
2Adaptability or versatility
If sheet joined portions with different shapes are used to improve elasticity distribution, then the adaptability is improved, but the first sheet layer and second sheet layer are not welded or are peeled due to weak bonding
Solution Approach 1:
The patent provides different types of sheet joined portions at different locations to achieve different elasticity distributions. The first type with smaller reference bonding diameter provides localized elasticity, while the second type with larger reference bonding diameter provides stronger bonding. This local differentiation allows both good elasticity distribution and strong bonding coexist
Solution Approach 2:
The patent creates a composite structure of sheet joined portions with different geometric characteristics within the same elastic member. This composite approach combines the benefits of different shapes (varying elasticity) while maintaining overall bonding strength through controlled parameter ranges that prevent welding defects
3Adaptability or versatility
If multiple sheet joined portions with different shapes are provided, then the adaptability and surface fitting are improved, but equipment wear and breakage occur early
Solution Approach 1:
The patent controls the reference bonding diameter and circumference length of sheet joined portions within specific ranges. By keeping these parameters within controlled limits, the patent prevents excessive stress concentration and equipment wear that would occur with highly varied shapes, while still allowing sufficient shape variation for good surface fitting
Data Source
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AI summary
A welding defect in the case of including sheet joined portions having different shapes is made difficult to occur. The above problem is solved by an elastic member having an elastic sheet stretchable structure 20X in which an elastic sheet 30 is interposed between a first sheet layer 20A made of a nonwoven fabric and a second sheet layer 20B made of a nonwoven fabric and the first sheet layer 20A and the second sheet layer 20B are welded through joint holes 31 penetrating the elastic sheet 30 at a plurality of sheet joined portions 40 arranged at intervals, in which a region having the elastic sheet stretchable structure 20X includes sheet joined portions 40 having different shapes, and in all the sheet joined portions 40 in the region having the elastic sheet stretchable structure 20X, a reference bonding diameter ϕ is 0.2 mm or more, a maximum value of the reference bonding diameter ϕ is 1 to 3 times a minimum value thereof, and a circumference length is 1 to 15 times a length of a circumference of a circle whose diameter is the reference bonding diameter ϕ.