Wire Harness Crimping Compression Rates for Corrosion Resistance
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Solution Overview
Problem
Conventional wire harnesses with different metal materials for electric wires and terminals, such as aluminum and copper, face corrosion issues due to moisture, leading to increased resistance and potential disconnection, and the manufacturing process complexity and cost of resin-filled connections are high.
Innovation Solution
A wire harness design with a crimping portion that includes a covering crimping portion made of polyvinyl chloride with a compression rate between 40% and 90% and a wire crimping portion with a compression rate between 50% and 80%, ensuring reliable water stopping performance by improving adhesion and tension strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different metals (aluminum wire and copper terminal) are used for cost and conductivity reasons, then electrical performance is improved, but corrosion resistance deteriorates due to electrolytic corrosion at the connection part
Solution Approach 1:
A resin material is introduced as an intermediary substance that fills the connection part between the aluminum wire and copper terminal. This resin barrier prevents moisture from reaching the metal contact surfaces, thereby eliminating the electrolytic corrosion mechanism while allowing the different metals to maintain their electrical connection functions
Solution Approach 2:
The resin material creates an inert, moisture-proof environment around the metal connection part. By filling the connection region with this protective resin, the harmful moisture and oxygen are excluded from the interface between different metals, preventing corrosion without compromising the electrical connection
2Object-affected harmful factors
If resin material is filled to cover the connection parts to prevent moisture infiltration, then corrosion resistance is improved, but manufacturing process complexity and cost increase
Solution Approach 1:
The resin filling operation is merged with the existing crimping process. The crimping tool simultaneously performs both the crimping action and the resin filling action in one integrated operation, eliminating the need for separate resin filling steps and reducing manufacturing complexity
Solution Approach 2:
The crimping tool is designed to automatically fill the resin material during the crimping process itself. The system uses its own crimping motion to drive the resin into the connection part, making the protective resin application self-contained within the existing manufacturing equipment without requiring additional specialized machinery
3Reliability
If compression rate for the covering portion is increased to improve water stopping performance, then adhesion is improved, but the covering portion material integrity may deteriorate
Solution Approach 1:
The compression rate parameter is precisely controlled within the optimal range of 40-90%. This parameter optimization ensures sufficient compression to create good adhesion and water stopping performance while staying below the threshold that would cause material damage or integrity loss in the polyvinyl chloride covering portion
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 design provides a reliable water stopping performance, enhances adhesion between the covering portion and the terminal, and increases the tension strength of the coated wire, effectively preventing corrosion and maintaining electrical characteristics.
Implementation Method 1
the compression rate for the coated wire being between 50% and 80% and the compression rate for the covering portion being between 40% and 90% at the covering crimping portion
Implementation Method 2
enhances adhesion between the covering portion and the terminal
Data Source
Figure 1
Figure 2(a)
Figure 2(b)
AI summary
Under compression by molds (31a, 31b), a wire (25), a covered area (27), and a crimping portion (5) are compressed and their cross-sectional areas decrease. Here, A1 is the cross-sectional area of the wire (25) after compression. That is, A1 is the sum of the cross-sectional area of the each strand after compression. Also, B1 is the cross-sectional area of the covered area (27) after compression. In the present invention, the compression rate for the wire (25) is set between 50 % and 80 %. Also, the compression rate for the covered area (27) is set between 40 % and 90 %. The amount of compression by the molds (31a, 31b) is set so that the compression rates are within these ranges. In the present invention, the compression rate is calculated by: (cross-sectional area after compression) / (cross-sectional area before compression). That is, 80 % compression rate means that the cross-sectional area has decreased by 20 % due to compression. That is, the relationships of 80 % ≥ (A1 / A0) ≥ 50 % and 90 % ≥ (B1 / B0) ≥ 40 % are satisfied.