Curved Elastic Thread Entrapment for Adhesive-Free Anchoring
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Solution Overview
Problem
Existing methods for manufacturing elastic composite structures in absorbent sanitary products face issues such as thread breakage and unreliable anchoring of elastic threads due to the use of adhesives and movement during thermal or ultrasonic welding, leading to undesirable tactile properties and increased costs.
Innovation Solution
An apparatus and method utilizing a rotary anvil with notches and angled facing surfaces to secure elastic threads between web layers through ultrasonic bonding without adhesives, ensuring the threads are anchored in position by frictional resistance, minimizing slip and thread breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesives are used to bond elastic threads within elastic composite structures, then the elastic threads can be secured between web layers, but the end product exhibits undesirable tactile properties (stiffness) and manufacturing costs increase
Solution Approach 1:
The patent replaces the adhesive bonding system with a mechanical anchoring system. The anvil features notches that mechanically capture and secure the elastic threads between web layers, eliminating the need for adhesives. This substitution resolves the contradiction by providing reliable bonding through mechanical means while maintaining the soft, flexible tactile properties of the non-woven material without adhesive stiffness.
2Ease of manufacture
If thermal or ultrasonic welding techniques are used to bond elastic threads, then adhesives are eliminated, but movement or shifting of elastic threads during manufacturing may result in thread breakage or unanchoring
Solution Approach 1:
The anvil notches are pre-formed on the anvil surface before the bonding process. These notches are designed to receive and securely hold the elastic threads in their correct positions during the ultrasonic welding process. This preliminary preparation prevents thread movement, shifting, breakage, or unanchoring that would otherwise occur during manufacturing, while maintaining ease of manufacture through a simple notching operation.
3Manufacturing precision
If elastic threads are held in a tensioned state during manufacturing, then the threads can be properly positioned, but the web material puckers or folds in the areas containing adhered elastic threads
Solution Approach 1:
The anvil notches serve as an intermediary structure between the tensioned elastic threads and the web material. The notches provide a controlled interface that holds the threads in their correct positions while allowing the web material to pass through without puckering or folding. This intermediary structure enables precise thread positioning while maintaining web material integrity and smooth appearance.
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 provides reliable anchoring of elastic threads, reducing thread breakage and eliminating the need for adhesives, thereby improving the manufacturing process efficiency and product quality.
Implementation Method 1
where the elastic threads are anchored between the web layers using ultrasonic welding
Data Source
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AI summary
An apparatus for manufacturing an elastic composite structure (102) includes a first roller (24) configured to transport a web layer (12) in a machine direction (14) and a laydown guide (42) configured to guide a laydown pattern of a plurality of elastic threads (18). A rotary anvil (32) comprising a first weld line (62) having a first notch (74) formed in a contact surface (82) of the first weld line (62), the first notch (74) having a first interior (89) configured to receive a portion of a first elastic thread (18) of the plurality of elastic threads (18) and a portion of the web layer (12) therein. The first notch (74) comprises a facing surface (86, 88) defining at least a portion of the first interior (89). A smallest orientation angle (98, 100) of a first face axis (92) normal to the facing surface (86, 88) with respect to a contact surface axis (94) normal to the contact surface (82) is a first angle that is less than 90 degrees.