Push-in Earplug with Thermal Bonded Foam Core
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Solution Overview
Problem
Push-in earplugs are costly and pose manufacturing challenges due to complex insertion mechanisms and material compatibility issues, which affect their ease of use and hygiene.
Innovation Solution
A method involving an elongate core made of a stiff material and an outer layer with an unactivated foaming agent, where the foaming agent is activated by heat to expand and bond thermally with the core, creating a sound attenuating portion and a stem portion with different densities for easy insertion and hygiene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If push-in earplugs are manufactured with complex insertion mechanisms, then ease of operation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The earplug is divided into two functional segments: a stiff elongate core that provides the push-in insertion mechanism, and a compressible sound attenuating portion that provides hearing protection. This segmentation allows each part to perform its specific function optimally while keeping the overall device simple.
Solution Approach 2:
The stiff elongate core acts as an intermediary element that the user grasps and manipulates during insertion. It mediates between the user's hand and the compressible sound attenuating portion, enabling easy push-in insertion without requiring the user to directly compress the attenuating portion.
2Manufacturing precision
If push-in earplugs are manufactured with complex assembly processes, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The manufacturing process merges the assembly of the core and outer layer into a single co-extrusion operation. The core and outer layer are formed and bonded simultaneously in one continuous process, eliminating separate assembly steps and reducing manufacturing complexity while maintaining precision.
Solution Approach 2:
The earplug uses composite materials with different properties (stiff core material and compressible outer layer material) that are bonded together through thermal bonding during co-extrusion. This allows precise control of material properties and bonding in a single manufacturing step.
3Object-affected harmful factors
If the outer layer is made highly compressible, then sound attenuation is improved, but structural stability deteriorates
Solution Approach 1:
Different parts of the earplug have different mechanical properties tailored to their specific functions: the outer layer is highly compressible for sound attenuation and ear canal conforming, while the elongate core is stiff for providing structural stability and enabling push-in insertion. This local differentiation of material properties optimizes both sound attenuation and structural stability.
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 simplifies manufacturing, reduces costs, and allows for direct insertion without compressing the sound attenuating portion, promoting hygiene and providing effective hearing protection.
Implementation Method 1
The outer layer includes a compressible sound attenuating portion and a stem portion that does not expand when the foaming agent is activated
Implementation Method 2
the outer layer includes a compressible sound attenuating portion and a stem portion bonded to the elongate core
Data Source
Figure 1~3D
Figure 4~6B
Figure 7A~7B
AI summary
A method of making an earplug (100), is disclosed. The method includes the steps of covering an elongate core (210, 310, 410) with an outer layer (220, 320, 420) that includes an unactivated foaming agent, positioning at least a portion of the outer layer in a mold (270, 370, 470), and activating the foaming agent such that a portion of the outer layer of at least a portion of the outer layer to form a sound attenuating portion (221, 321, 421) and a stem portion (222, 322, 422) bonded to the elongate core.