Lobular Screwdriver and Screw Socket for Angled Torque Transfer
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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 accelerated wear due to torque transmission methods, and lack a reliable non-magnetic attachment for non-ferromagnetic screws.
Innovation Solution
A screwdriver with a lobular screw engaging configuration featuring a solid core with protruding 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, and enabling compatibility with standard Torx and hex 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 of the polygonal head causing rapid wear and rounding off
Solution Approach 1:
The screwdriver head is segmented into a central core and multiple protruding longitudinal ribs. This segmentation distributes the torque transmission across multiple contact points (ribs) rather than concentrating stress on edges, thereby reducing wear while maintaining torque transmission capability.
Solution Approach 2:
The central core has a convex longitudinal cross-section (curved surface) instead of a flat or sharp-edged polygonal shape. This curvature distributes contact stress more evenly across the engagement surface with the screw, reducing stress concentration and edge wear during angled fastening operations.
2Reliability
If protruding ribs are added to transmit torque, then edge wear is reduced, but the shape does not allow for precise fitting between screwdriver and screw
Solution Approach 1:
Different parts of the screwdriver head have different geometric properties optimized for their specific functions: the central core provides precise fitting through its regular polygonal transversal cross-section and convex longitudinal shape, while the protruding longitudinal ribs provide torque transmission and wear resistance. This local differentiation of geometric qualities resolves the contradiction between precise fitting and wear resistance.
3Ease of operation
If magnetic attachment is used between screwdriver and screw, then attachment is achieved, but it is incompatible with non-ferromagnetic materials like titanium used in medical applications
Solution Approach 1:
The patent replaces magnetic attachment (electromagnetic field-based) with a mechanical friction-attachment system based on the friction-attachment between the screwdriver's lobular configuration and the screw's complementary grooves. This mechanical system works with all materials including non-ferromagnetic titanium, thereby achieving both ease of operation and material compatibility.
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 solution provides reliable torque transmission and reduced wear on the screwdriver and screw surfaces, maintaining friction-coupling effectiveness for longer periods and allowing angled fastening with reduced stress, while being compatible with standard screwdrivers.
Implementation Method 1
maintaining friction-coupling effectiveness for longer periods
Data Source
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.