Opposite-Lay Hollow Stranded Wire for Pushability and Torque Followability
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Solution Overview
Problem
Hollow coils used in medical devices face challenges with insufficient pushability and rotation followability, as larger inner diameters lead to stretching and looseness of twist, affecting their performance during medical procedures.
Innovation Solution
A hollow stranded wire design featuring a first layer of twisted flat wires and a second layer of oppositely twisted flat wires, with specific diameter and thickness ratios, enhances pushability and rotation followability by preventing stretching and twist looseness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the inner diameter of the hollow coil is set large, then the coil can accommodate another member for medical treatment, but the coil easily stretches and pushability is impaired
Solution Approach 1:
The hollow coil is segmented into multiple layers (first layer and second layer) with opposite winding directions. This segmentation allows each layer to contribute differently to the overall structure, with the first layer providing pushability and the second layer preventing over-stretching, thereby maintaining both large inner diameter and adequate pushability
Solution Approach 2:
The invention changes the winding direction parameter of the second layer to be opposite to the first layer. This parameter change creates a structural configuration where the layers work in opposition to each other, preventing excessive stretching while maintaining the required inner diameter for medical device insertion
2Ease of operation
If the coil is rotated in the direction opposite to the winding direction, then the coil can rotate freely, but looseness of twist easily occurs and rotation followability is impaired
Solution Approach 1:
The coil structure is segmented into multiple layers with opposite winding directions, where each layer provides rotational stability in opposite directions. This segmentation ensures that when the coil rotates in one direction, the layer wound in the opposite direction prevents excessive loosening, maintaining both rotation followability and twist stability
Solution Approach 2:
The second layer acts as a counterbalance to the first layer, with its opposite winding direction providing a counteracting force that prevents excessive loosening during rotation. This counterbalancing structure maintains the coil's twist stability while allowing necessary rotation for medical procedures
3Strength
If two wires are wound to form the hollow coil, then pushability is improved, but rotation followability is still insufficient
Solution Approach 1:
The coil is segmented into multiple layers with opposite winding directions, where the first layer provides pushability and the second layer contributes to rotation followability. This segmentation allows each layer to optimize for its specific function while working together as an integrated structure
Solution Approach 2:
The invention uses a composite structure combining multiple layers with different winding directions. This composite configuration integrates the pushability benefits of multi-wire construction with the rotation followability benefits of opposite-direction winding, achieving both performance requirements simultaneously
4Ease of operation
If a two-layer structure with opposite winding directions is used, then rotation followability is excellent, but pushability is insufficient
Solution Approach 1:
The invention optimizes parameters such as the number of turns, wire diameter, and winding tension for each layer to balance rotation followability and pushability. By carefully adjusting these parameters, the structure achieves both excellent rotation followability from the opposite winding directions and sufficient pushability through appropriate layer configuration
Data Source
AI summary
A hollow stranded wire (2) has a first layers (4) and second layers (6). The second layer is located outside the first layer. The first layer is formed by twisting eight first element wires (8) which are flat wires. The second layer is formed by twisting eight second element wires (10) which are flat wires. A ratio (Ww/Tw) of a width Ww to a thickness Tw of each flat wire is from 2 to 11. A twisting direction of the second element wires is opposite that of the first element wires. A twisting angle of each first element wire is not greater than 85°. A twisting angle of each second element wire is not greater than 85°. A ratio (D/T) of an average diameter D to a thickness T of the hollow stranded wire is not less than 5 and not greater than 20.