Laterally Wound Shield Cable for Bending and Torsion Resistance
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Solution Overview
Problem
Conventional cables used in small industrial robots, medical applications, and automobiles face challenges in maintaining resistance to bending and torsion, leading to potential wire breakage and sheath cracking.
Innovation Solution
A cable design featuring a cable core with electric wires, a laterally wound shield layer composed of semi-rigid copper alloy wire strands, and a thin sheath, where the winding pitch ratio (P/PD) is less than 9.9, enhancing bending resistance and preventing sheath cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cables are used in applications requiring repeated bending and torsion, then the cable structure remains simple, but the resistance to bending deteriorates leading to wire breakage and sheath cracking
Solution Approach 1:
The patent changes the geometric parameters of the laterally wound shield by controlling the winding pitch ratio (P/PD < 9.9) and uses semi-rigid copper alloy wires with specific mechanical properties (tensile strength 200-500 MPa, elongation 5-20%). These parameter changes optimize the shield's ability to distribute bending stresses, preventing wire breakage while maintaining cable flexibility.
Solution Approach 2:
The patent employs a composite structure combining semi-rigid copper alloy wires with the sheath material. The semi-rigid copper alloy provides enhanced tensile strength and elongation properties that conventional soft copper cannot achieve, creating a composite system that resists wire breakage during repeated bending and torsion cycles.
2Ease of operation
If the sheath is made thinner to reduce cable diameter, then the cable becomes more flexible, but the sheath cracking resistance deteriorates
Solution Approach 1:
The patent optimizes the winding pitch ratio (P/PD) of the laterally wound shield to be less than 9.9, which changes the stress distribution pattern on the sheath during bending. This parameter change allows the sheath to withstand repeated bending cycles without cracking, even when the sheath thickness is reduced to achieve smaller cable diameter and improved flexibility.
3Reliability
If a laterally wound shield with semi-rigid copper alloy wire is used, then the resistance to bending is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent establishes a specific parameter range for the winding pitch ratio (P/PD < 9.9) that balances manufacturing ease with performance. This parameter constraint provides clear manufacturing guidelines while achieving the desired bending resistance, making the laterally wound shield processable with conventional equipment without excessive complexity.
Data Source
AI summary
A cable is provided with a cable core including one or more electric wires, a shield layer provided to cover around the cable core and composed of a laterally wound shield formed by winding metal wire strands helically, and a sheath provided to cover around the shield layer. The metal wire strands are semi-hard copper alloy wires, and P/PD, which is the ratio of the winding pitch P in the laterally wound shield to the pitch diameter PD of the shield layer, is less than 9.9.