Flat Wire Coil Twist Contraction to Prevent Coil Jumping
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Solution Overview
Problem
Wire guides with a solid core and flat wire coil often experience 'coil jumping' due to a radial gap between the mandrel and coil, making them unusable when packaged and unwound, as the coil does not self-correct upon unpackaging.
Innovation Solution
A twist contraction strategy is employed where a flat wire coil is torqued to create tension, reducing its inner diameter and minimizing the radial gap between the coil and mandrel, with attachments at both distal and proximal locations to maintain this tension and increase stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coil is compressed from proximal end toward distal end to reduce radial gap, then the coil jumping is reduced, but the manufacturing complexity increases due to additional compression steps
Solution Approach 1:
The flat wire is pre-formed into a coil with a rest inner diameter larger than the mandrel outer diameter, allowing the mandrel to be slid in easily. The compression is then applied as a preliminary action before final attachment, ensuring the coil maintains contact with the mandrel throughout the manufacturing process and prevents coil jumping during packaging and use.
Solution Approach 2:
The wire guide is divided into three main segments: the solid core mandrel, the flat wire coil, and the attachment regions. This segmentation allows independent optimization of each component - the mandrel provides structural support, the coil provides flexibility and positioning, and the attachment regions secure the assembly. The distal attachment location is positioned closer to the distal end than the proximal attachment location, creating an asymmetric segmentation that optimizes performance.
2Ease of manufacture
If the rest inner diameter of the coil is made greater than the mandrel outer diameter to facilitate assembly, then the ease of manufacture is improved, but the radial gap causes coil jumping during packaging
Solution Approach 1:
The inner diameter of the coil is changed from its rest state value (larger than mandrel) to a compressed state value (smaller than mandrel) through application of compressive force. This parameter change occurs during manufacturing and maintains the coil in a stable configuration that prevents jumping during packaging and use, while the rest state still allows easy assembly.
3Strength
If the coil is compressed to reduce radial gap, then the structural integrity is improved, but the coil length may deviate from mandrel length
Solution Approach 1:
The flat wire coil is designed to be flexible and adaptable in length. During the compression process, the coil dynamically adjusts its length to match the mandrel length. The attachment process secures the coil at specific locations (distal and proximal) while allowing the intermediate portion to conform to the mandrel length through the tension in the flat wire, ensuring both structural integrity and precise length matching.
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 reduces the likelihood of coil jumping during packaging and unwinding, resulting in a stiffer wire guide with a reduced inner diameter and winding gap, enhancing the structural integrity and usability of the wire guide.
Implementation Method 1
The flat wire is in tension between the proximal attachment location and the distal attachment location so that the flat wire coil has a reduced inner diameter, which is smaller than the rest inner diameter
Data Source
AI summary
A wire guide includes a solid core mandrel that is initially received in a flat wire coil that has a rest inner diameter that is greater than a uniform diameter of the solid core mandrel. The flat wire of the flat wire coil is in tension between a proximal location and a distal location so that the flat wire coil has a reduced inner diameter that is smaller than its rest inner diameter. The tension in the flat wire is introduced by torquing the mandrel relative to the flat wire coil as part of attaching the coil to the mandrel.