Flat Cable Conductor Alloy Design for Buckling Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flat cables used in rotatable connector devices for vehicles have insufficient bending properties, leading to buckling issues, which is a concern for the increasing durability and reliability requirements in modern automobiles.
Innovation Solution
A flat cable design with conductors made of a copper alloy containing specific elements (tin, magnesium, chromium, zinc, titanium, zirconium, iron, phosphorus, silicon, silver, and nickel) within defined concentration ranges, combined with a laminated structure and controlled grain size, to achieve improved elasticity and resistance to buckling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the conductor uses conventional copper alloy with grain size control only, then the manufacturing process is simple, but the bending property is insufficient and buckling occurs
Solution Approach 1:
The patent changes multiple parameters of the copper alloy conductor simultaneously: adding specific alloying elements (Sn: 0.01-1.0%, Mg: 0.01-1.0%, Cr: 0.01-0.5%, Zn: 0.1-5.0%, Ti: 0.02-0.3%, Zr: 0.01-0.2%, Fe: 0.01-3.0%, P: 0.001-0.2%, Si: 0.01-0.3%, Ag: 0.01-0.3%, Ni: 0.1-1.0%) and controlling grain size to 10 μm or smaller. This multi-parameter optimization resolves the contradiction by achieving superior bending properties through compositional and microstructural control while maintaining manufacturing feasibility.
Solution Approach 2:
The patent creates a composite copper alloy system by combining base copper with multiple alloying elements that serve different functions: Sn, Mg, and Zn for solid solution strengthening; Cr, Ti, and Zr for precipitation hardening; and P for grain boundary strengthening. This composite material approach enables the conductor to achieve both high bending resistance and manufacturability.
2Ease of operation
If the conductor elongation is increased to 5% or more, then the rigidity decreases making it easier to fold, but the bending property remains insufficient and buckling still occurs
Solution Approach 1:
The patent optimizes the balance between elongation and bending property by controlling alloy composition and grain size. The specific ranges of alloying elements and the 10 μm grain size limit create a microstructure that provides both sufficient ductility for folding and high resistance to buckling, resolving the contradiction between ease of operation and bending reliability.
3Strength
If the conductor uses high strength copper alloy, then the resistance to buckling improves, but the electrical conductivity decreases
Solution Approach 1:
The patent carefully selects alloying element types and concentrations to minimize impact on electrical conductivity while maximizing mechanical strength. By using elements like Cr, Ti, and Zr for precipitation hardening rather than extensive solid solution strengthening, and by controlling grain size to 10 μm or smaller, the patent achieves high buckling resistance while maintaining electrical conductivity above 50% IACS.
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 solution enhances the bending property and durability of the flat cable, preventing plastic deformation even after numerous bending cycles, thus improving the reliability and safety of the cable in applications like steering wheel connectors.
Implementation Method 1
in which crystal grains are refined to 7 μm or smaller
Implementation Method 2
there is proposed a flat conductor obtained by performing heat treatment on a flat-shaped conductor
Implementation Method 3
an adhesive layer provided between the pair of insulating films
Data Source
Figure 1
AI summary
There is provided a flat cable having a good folding property and inhibiting occurrence of buckling while maintaining an electrical conductivity equivalent to an electrical conductivity of a conventional flat cable, so as to achieve further improvement in a bending property. A flat cable is a flat cable including a predetermined number of conductors, a pair of insulating films disposed in such a manner as to sandwich the predetermined number of conductors, and an adhesive layer provided between the pair of insulating films, wherein the conductors each satisfy Y ≥ 1.2 × t × E / (2X - t) within a range of bending radius of 4 mm to 8 mm, where X (mm) denotes bending radius, Y (MPa) denotes 0.2% yield stress, t (mm) denotes thickness, and E (MPa) denotes Young's modulus, and the conductors each have an electrical conductivity of greater than or equal to 50% IACS.