High-Voltage DC Cable Joint Platinum Cured Rubber
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Solution Overview
Problem
Current manufacturing methods for high-voltage DC cable joints using EPDM rubber are labor-intensive and costly due to the high viscosity of uncured EPDM, requiring multiple process steps and degassing to remove volatile by-products from radical curing reactions, which can negatively impact electric properties.
Innovation Solution
A method involving a multi-wall layered construction with concentrically arranged layers, using platinum-cured rubbers and ultraviolet (UV) radiation curable rubber layers, eliminating the need for peroxide curing agents and subsequent degassing, through injection moulding and UV curing in a by-product-free process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If peroxide curing is used for EPDM rubber layers, then cross-linking and structural stability are achieved, but volatile by-products are generated requiring degassing which complicates the manufacturing process and may negatively impact electric properties
Solution Approach 1:
The patent changes the curing chemistry parameters by replacing peroxide-based radical curing with platinum-catalyzed addition curing. This parameter change eliminates the formation of volatile by-products while maintaining effective cross-linking, thereby resolving the contradiction between achieving structural stability and avoiding manufacturing complexity associated with degassing.
Solution Approach 2:
The invention converts the harmful effect of volatile by-product generation into a benefit by selecting a curing mechanism (platinum-catalyzed addition) that inherently avoids by-product formation. The curing reaction produces only stable cross-linked structures without low molecular weight volatiles, eliminating the need for degassing operations.
2Manufacturing precision
If multiple process steps with sequential curing are used, then proper curing of each layer is achieved, but manufacturing time and labor intensity increase
Solution Approach 1:
The patent merges multiple sequential curing operations into a single unified curing step. By formulating all rubber layers to be compatible with platinum-catalyzed curing, all layers can be cured simultaneously in one operation rather than requiring separate curing cycles for each layer, thereby maintaining curing quality while significantly improving manufacturing efficiency.
Solution Approach 2:
The invention creates a universal curing system where platinum-catalyzed addition curing serves as a common curing mechanism for all rubber layers (conductive layers and field grading layer). This multi-functional approach eliminates the need for layer-specific curing procedures, reducing manufacturing steps while ensuring proper curing of all components.
3Shape
If uncured EPDM rubber is wound around mandrel and then compression molded, then layer formation is achieved, but the high viscosity of uncured EPDM makes the process labor-intensive and costly
Solution Approach 1:
The patent replaces the mechanical compression molding process with injection molding. Instead of manually or mechanically winding high-viscosity uncured rubber and then compression molding it, the injection molding process directly forms the cured layers by injecting the rubber compound into a mold, eliminating the labor-intensive winding and compression steps while maintaining proper layer formation.
Solution Approach 2:
The invention performs preliminary curing action by incorporating the platinum catalyst system into the rubber compound before molding. The curing reaction is initiated during or immediately after injection molding, allowing the layers to form in their final cured state directly in the mold, thereby eliminating subsequent compression molding and manual handling of high-viscosity material.
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 approach results in a high-voltage DC cable joint with optimal electrical and mechanical properties, reduced manufacturing complexity, and scalability to higher voltage ratings, ensuring homogeneous curing and minimizing conductivity variations, while avoiding the need for degassing and reducing labor and costs.
Implementation Method 1
The insulating rubber layer may be an ultraviolet (UV) curable rubber layer, and the method may comprise curing by using an ultraviolet (UV) radiation transparent mould
Implementation Method 2
using platinum-cured rubbers and ultraviolet (UV) radiation curable rubber layers, eliminating the need for peroxide curing agents and subsequent degassing
Data Source
AI summary
A high-voltage DC cable joint including a multi-wall layered construction having individual concentrically arranged layers. The joint includes, from inside to outside, an inner conductive rubber layer, a field grading rubber layer made from a predetermined tailored formulation, an insulating rubber layer and an outer conductive rubber layer. The field grading rubber layer separates and interconnects the conductive rubber layers, and wherein the rubber layers are cross-linked by a by-product-free manufacturing method. The cable joint is preferably made from platinum cured rubbers by moulding process steps. In a preferred embodiment the cable joint is made by injection moulding.