Wire Insulation Extrusion Curing Process
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Solution Overview
Problem
Existing wire manufacturing methods, such as historical heat-curing and electron beam (e-beam) methods, face challenges in producing wires that meet increasingly demanding technical specifications, including abrasion resistance and flexibility, while being cost-effective and efficient, as they can result in incomplete curing, equipment expense, and difficulty with thick wall wires.
Innovation Solution
A method involving extrusion of cross-linkable polymers around a conductive core without curing agents, followed by immersion in a curing agent bath and heat curing, which achieves properties similar to e-beam methods without the need for radiation, allowing for efficient production of wires that meet stringent specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If historical heat-curing methods are used to manufacture wire, then manufacturing efficiency is improved and costs are reduced, but the wire fails to meet technical specifications for abrasion resistance
Solution Approach 1:
The manufacturing process is segmented into two distinct stages: (1) extrusion of cross-linkable polymers without curing agents to form the insulative layer, and (2) subsequent addition of curing agents after extrusion. This segmentation prevents premature cross-linking during extrusion while enabling controlled curing afterward, thereby achieving both manufacturing efficiency and desired abrasion resistance properties.
Solution Approach 2:
The cross-linkable polymers are extruded in advance without curing agents, creating a stable green state insulative layer that can be processed at normal extrusion temperatures. The curing action is then applied subsequently, allowing the extrusion process to proceed efficiently while the final curing step confers the required abrasion resistance.
2Reliability
If e-beam manufacturing methods are used to improve abrasion resistance, then technical specifications are met, but equipment expense and manufacturing complexity increase
Solution Approach 1:
The patent replaces the e-beam radiation system with a chemical curing agent system. Instead of using expensive and complex e-beam equipment to initiate cross-linking, the invention uses chemically active curing agents that react with the cross-linkable polymers under milder, more controllable conditions, thereby achieving the same abrasion resistance without the complexity of radiation equipment.
Solution Approach 2:
The curing process parameters are changed from high-energy radiation (e-beam) to chemical reaction conditions. The curing agents enable cross-linking to proceed at lower energy inputs and more controllable temperatures, simplifying the manufacturing process while maintaining the desired wire properties.
3Productivity
If all starting materials are added to the extruder at the same time, then manufacturing line speed is maintained, but premature cross-linking occurs causing scorching
Solution Approach 1:
The curing agents are extracted from the extrusion process and added separately after extrusion. By removing the curing agents from the extruder, the process avoids premature cross-linking and scorching during extrusion, while still enabling complete curing afterward. This extraction allows maintenance of manufacturing line speed without the harmful effects of early curing.
Solution Approach 2:
The cross-linkable polymers are extruded in a stable, uncured state first, allowing the extrusion process to proceed at normal speeds without risk of scorching. The curing action is then applied as a subsequent step, separating the extrusion and curing functions to prevent harmful premature cross-linking.
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
This method produces wires with improved abrasion resistance and flexibility, meeting technical specifications like ISO 6722 standards, while reducing manufacturing costs and complexity, and enabling higher manufacturing line speeds.
Implementation Method 1
heat cured at temperatures ranging from about 135° C. to about 155° C. for a length of time to cause sufficient cross-linking in the insulative layer or layers
Implementation Method 2
heat cured at temperatures ranging from about 135° C. to about 155° C.
Implementation Method 3
feeding a conductive core into an extruder wherein at least one insulative layer was extruded about the conductive core
Data Source
AI summary
Exemplary methods for manufacturing a wire and resultant wires are disclosed herein. The method includes extruding a cross-linkable polymer that is substantially free of curing agent about a conductive core, then adding a curing agent to the extruded wire pre-product, then heat-curing the extruded wire pre-product.