Pin-Drive Surgical Tool Coupling for Self-Alignment and Torque Transfer
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Solution Overview
Problem
Current rotary surgical cutting tools face issues with torque transmission and alignment due to high contact stresses and reduced interface stiffness, leading to reliability concerns and user frustration during surgical procedures.
Innovation Solution
The surgical cutting tool features an elongated shaft with a coupling portion and interface structures that include deflection surfaces, allowing for self-alignment with the drive chuck's pins, enhancing torque transfer and alignment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If complex machining/grinding is used to achieve torque transmission and axial retention features, then torque transmission capability is improved, but contact stresses increase and interface stiffness is reduced
Solution Approach 1:
The coupling portion is segmented into multiple interface structures (first and second interface structures) with distinct driven surfaces. This segmentation distributes the torque transmission across multiple contact points rather than relying on complex machining of a single interface, thereby maintaining torque capability while reducing contact stresses at any single point.
Solution Approach 2:
The patent transitions from point contacts (single-axis rotation) to surface contacts by creating first and second driven surfaces that extend in multiple dimensions. This dimensional change increases the contact area between the coupling portion and drive chuck, reducing contact stresses while maintaining robust torque transmission.
2Ease of manufacture
If traditional cylindrical shank design is used, then manufacturing is simplified, but alignment between shank and drive chuck becomes problematic
Solution Approach 1:
The coupling portion incorporates asymmetric features including oblique surfaces and non-circular drive surfaces that provide inherent alignment guidance. These asymmetric elements ensure proper orientation of the cutting tool relative to the drive chuck during insertion, eliminating alignment problems associated with symmetric cylindrical designs while maintaining manufacturing feasibility.
Solution Approach 2:
The coupling portion is designed with pre-configured interface structures and oblique surfaces that automatically guide alignment during the insertion process. This preliminary alignment action occurs before the tool is fully seated, ensuring precise positioning without requiring complex adjustment procedures or high-precision machining.
3Device complexity
If point contacts are used for driven interface, then device complexity is reduced, but torque transmission efficiency is insufficient
Solution Approach 1:
The patent replaces point contacts with surface contacts by creating first and second driven surfaces that extend across multiple dimensions. This dimensional transition increases the contact area and improves torque transmission efficiency while maintaining relatively simple interface structures that do not require complex mechanisms.
4Adaptability or versatility
If traditional drive chuck interface is used, then compatibility with existing tools is maintained, but alignment and reliability issues arise
Solution Approach 1:
The coupling portion is divided into multiple interface structures with distinct driven surfaces, allowing each surface to be optimized for specific functions (torque transmission, alignment, axial retention). This segmented approach maintains compatibility with standard drive chuck configurations while improving overall connection reliability through distributed contact and reduced stress concentrations.
Data Source
AI summary
A surgical cutting tool includes an elongated shaft and a cutting head. The shaft defines a coupling portion terminating at a proximal end of the shaft, a stem portion, and a distal portion. The stem portion defines a central axis. The coupling portion optionally defines a deflection surface positioned oblique with respect to the central axis and connected with a first driven surface and a second driven surface. Upon insertion into a drive chuck, the deflection surface promotes self-alignment of the cutting tool and the drive chuck.