Cold-Drawn EVA Earplug Cord for Reduced Deformation
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Solution Overview
Problem
Conventional earplug cords made from ethylene vinyl acetate (EVA) are too elastic and prone to plastic deformation, which complicates material handling during manufacturing and affects the stability of the earplug assembly.
Innovation Solution
Cold drawing the EVA cord by uniaxially stretching it to increase its elastic modulus, reducing its elasticity and susceptibility to deformation, and fixing it to the earplugs to form a more stable assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional EVA cord is used in earplugs, then the cord is flexible and easy to attach, but the cord is too elastic and prone to plastic deformation
Solution Approach 1:
The patent applies parameter changes by modifying the elastic modulus of the EVA cord through controlled deformation during manufacturing. The cord is subjected to specific tensile loads and thermal conditions to permanently alter its mechanical properties, reducing elasticity from conventional levels to a controlled range (elastic modulus of 10-100 MPa) while maintaining flexibility for attachment.
2Stability of the object's composition
If the elasticity of the cord is reduced to minimize deformation, then the stability improves, but the cord becomes less flexible and more difficult to handle during manufacturing
Solution Approach 1:
The patent applies preliminary action by pre-deforming the cord during the manufacturing process to achieve the desired elastic modulus before the cord is used in the final product. The cord is subjected to controlled tensile loading and thermal treatment in advance, which permanently sets its mechanical properties, making it easier to handle during subsequent manufacturing steps while maintaining stability in the final assembly.
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 cold-drawn EVA cord exhibits an elongation to break of 250% or less and an elastic modulus of 10 MPa or greater, improving material handling and stability in earplug assemblies by minimizing undesirable deformation.
Implementation Method 1
Cold drawing ethylene vinyl acetate cord increases its elastic modulus to provide a less 'springy' or less elastic cord when fixed to one or more earplugs
Implementation Method 2
the flexible cord being a cold-drawn cord and having an elongation to break of 250% or less and an elastic modulus of 10 MPa or greater at 100% elongation
Data Source
AI summary
An earplug assembly and method of forming the same is described. The method includes uniaxially stretching a cord formed of copolymer including ethylene segments and vinyl acetate segments to form a cold-drawn cord. The cold drawn cord has an elongation to break of 250% or less. The method then includes fixing the cold drawn cord to an earplug.