Star-Shaped Collet for High-Tension Polymer Cable Grip
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Solution Overview
Problem
Polymer-based surgical cables are difficult to securely lock under high tension due to slippery surfaces, material deformation, and delicate fibers, which existing gripping mechanisms often damage or fail to maintain a consistent grip.
Innovation Solution
A bio-compatible gripping device with a collet and retaining collar system that applies uniform pressure over a large surface area, using a star-shaped collet with radially inward-moving fingers to grip the cable, maintaining pressure consistency as the cable shrinks under tension, and a crimping tube or attachment tabs for secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gripping mechanisms are used on polymer cables, then the cable can be secured, but the slippery surface and material deformation cause the grip to fail under high tension
Solution Approach 1:
The gripping device features localized gripping surfaces with specific geometric profiles that conform to the cable surface. The fingers have tapered leading edges and flattened contact surfaces that create localized high-friction zones, allowing the device to exploit local surface properties rather than relying on overall cable surface characteristics.
Solution Approach 2:
The gripping fingers incorporate curved and rounded surfaces that match the cylindrical geometry of the cable. The contact surfaces are arched to distribute pressure evenly around the cable circumference, preventing stress concentration on the slippery polymer surface while maintaining consistent frictional engagement.
2Force
If increased pressure is applied to prevent slippage, then the grip strength improves, but the cable fibers are damaged or frayed
Solution Approach 1:
The gripping force is divided into multiple discrete contact points along the cable surface. Instead of one large contact area, the device uses several fingers that each apply a portion of the total gripping force, distributing the mechanical stress across multiple locations and preventing localized fiber damage.
Solution Approach 2:
The gripping device incorporates flexible fingers that can dynamically adjust their position and contact pressure in response to cable deformation. As the cable shrinks or moves under tension, the fingers flex to maintain optimal contact without exceeding the cable's stress tolerance, providing adaptive force distribution.
3Stability of the object's composition
If the gripping device is made rigid to maintain consistent grip, then the grip stability improves, but the device cannot adapt to cable diameter changes under tension
Solution Approach 1:
The gripping device transitions from a static rigid structure to a dynamic system where fingers can flex and move independently. This allows the device to maintain stable overall geometry while accommodating local cable dimension changes, combining structural stability with adaptive flexibility.
Solution Approach 2:
The gripping fingers are constructed as thin-walled flexible structures that can bend and deform elastically. These flexible elements maintain their structural integrity while adapting to cable diameter variations, providing consistent gripping force despite changes in cable geometry under tension.
4Stability of the object's composition
If the number of gripping fingers is increased to improve grip uniformity, then the pressure distribution improves, but the device complexity and insertion force increase
Solution Approach 1:
The gripping device uses a standardized finger design that can be replicated multiple times around the cable circumference. Each finger performs the same gripping function, allowing the system to achieve uniform pressure distribution through simple repetition rather than complex differentiated structures. The optimal number of fingers (7-11) balances pressure uniformity with manageable device complexity.
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 device effectively maintains a firm, uniform grip on polymer cables under high tension without damaging them, ensuring stability throughout the healing process by distributing force over a large area and maintaining pressure consistency during cable diameter changes.
Implementation Method 1
the collet is configured to be inserted into the passage of the retaining collar to compress the sidewall toward the central longitudinal axis to provide a pressure to a surgical cable
Implementation Method 2
The device effectively maintains a firm, uniform grip on polymer cables under high tension... by distributing force over a large area
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3E
AI summary
This disclosure describes embodiments of bio-medically compatible gripping devices capable of radial collapse or compression in accordance with the shrinkage of a nylon or other polymeric material cored surgical cable (103) undergoing tension, while maintaining a firm grip throughout the process of shrinkage of the cable. The present embodiments can provide a gripping device capable of maintaining a grip on an outer surface of a slippery delicate cable, the grip being approximately (e.g., substantially) uniform along both the length and circumference of the gripped portion of the cable. The present embodiments can also provide a gripping device capable of maintaining a grip on, yet not damage, a delicate cable under high tension for a period of time adequate for the healing process to occur (e.g., the healing of a bone fracture).