Lobular Screwdriver Interface for Angled Torque Without Edge Wear
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Solution Overview
Problem
Existing screw and screwdriver configurations for angled fastening, particularly in medical and dental applications, face issues such as stress concentration and wear on edges, imprecise fitting, and inability to maintain friction-attachment without accelerating wear, especially when using non-ferromagnetic materials like titanium.
Innovation Solution
A screwdriver with a lobular screw engaging configuration featuring a solid core surrounded by longitudinal ribs and a screw with a tapered central socket and longitudinal grooves, allowing torque transmission up to 25° while reducing stress and wear through friction-coupling surfaces, compatible with various standard screwdrivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hexagonal ball screwdriver configuration is used for angled fastening, then torque transmission is achieved, but stress concentrates on the edges causing rapid wear and rounding of the polygonal head
Solution Approach 1:
The patent replaces the polygonal head with a spherical core surrounded by longitudinal ribs. The spherical geometry distributes stress uniformly across the surface rather than concentrating it on edges, eliminating the rounding problem while maintaining torque transmission capability through the rib structures.
Solution Approach 2:
The spherical core is segmented by adding longitudinal ribs that create distinct engagement zones. These ribs divide the continuous spherical surface into structured segments that can transmit torque through defined contact areas, combining the stress-distribution benefit of spherical geometry with the torque-transmission efficiency of segmented structures.
2Reliability
If protruding ribs are added to create a hexa-lobular configuration, then wear is reduced, but precise fitting between screwdriver and screw is compromised
Solution Approach 1:
The patent applies different geometric properties to different parts of the engagement interface: the core is spherical for uniform stress distribution, while the longitudinal ribs provide localized precision engagement features. This local differentiation allows each region to optimize its function - the sphere handles stress distribution while the ribs ensure precise fitting.
3Reliability
If magnetic attachment is used between screwdriver and screw, then secure attachment is achieved, but it is incompatible with non-ferromagnetic materials like titanium required for medical applications
Solution Approach 1:
The patent replaces magnetic attachment (electromagnetic field-based) with a mechanical friction-attachment system based on the lobular spherical configuration. The longitudinal ribs create friction-based engagement that secures the screw in the screwdriver without requiring magnetic properties, enabling compatibility with non-ferromagnetic materials like titanium.
4Adaptability or versatility
If friction-attachment is implemented for non-magnetic materials, then material compatibility is maintained, but the attachment strength may be insufficient for secure fastening
Solution Approach 1:
The engagement interface combines different geometric features (spherical core + longitudinal ribs) to create a composite structural system that leverages both friction-based attachment (for material compatibility) and mechanical interlocking (for attachment strength). The ribs create multiple contact points that collectively provide sufficient holding force.
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
Enables secure, wear-resistant, and precise angled fastening of screws in medical and dental applications, maintaining friction-coupling surfaces undamaged for longer periods and accommodating different screwdriver types without accelerated wear.
Implementation Method 1
the screw and complementary screwdriver being adapted to produce releasable friction-attachment between the screw and the screwdriver
Data Source
Figure 1~2
Figure 3~4C
Figure 5
AI summary
Screw, screwdriver and screw fastening set, the screwdriver (1) comprising a screw engaging configuration (10) with a core (11) surrounded by a number of protruding longitudinal ribs (12) elongated in the longitudinal driver axis (DA) direction and radially distributed around the core (11) in radial symmetry, and wherein successive transversal cross-sections of the core (11), perpendicular to the longitudinal driver axis (DA), have a regular polygonal shape, longitudinal cross-sections of the core (11), coincident with the longitudinal driver axis (DA), have a convex shape, and each protruding longitudinal rib (12) is connected to the core (11) on an edge between two adjacent arched convex surfaces of the core, a central portion (13) of each side of the regular polygonal shape being exposed for coupling into a complementary flat surface of a driver engaging configuration of the screw, providing friction-retention between the screw and the screwdriver.