Concave Drive Profile Geometry for Coaxial High-Torque Engagement
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Solution Overview
Problem
Existing drive systems for screws and turning tools often suffer from unintentional detachment of driving profiles, inability to achieve coaxial alignment, and damage to drive surfaces due to high torque applications.
Innovation Solution
The drive element features an outer or inner driving profile with concave drive surfaces and inclined transition surfaces, ensuring that normal forces during torque transmission are directed tangentially to the drive surfaces, avoiding loading of the transition areas and promoting a secure, coaxial connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional driving profiles with flat drive surfaces are used, then the structure is simple, but the drive surfaces become damaged under high torque and the profiles can detach unintentionally
Solution Approach 1:
The patent applies curvature by replacing flat drive surfaces with concave arc-shaped drive surfaces that follow a circular path. This curvature allows the drive surfaces to better distribute contact forces and prevents edge damage while maintaining structural simplicity through the use of uniform circular geometry.
Solution Approach 2:
The patent changes the geometric parameters of the drive surfaces by defining specific relationships between the inner diameter Di, outer diameter Da, and center-to-center distance L. These parameter changes ensure that normal forces are directed tangentially to the drive surfaces, preventing damage while maintaining manufacturing feasibility.
2Reliability
If magnetic turning tools are used to prevent detachment, then holding force is improved, but coaxial alignment cannot be achieved and additional cost is incurred
Solution Approach 1:
The conical shape with inclined drive surfaces creates a self-aligning mechanism where the inclined surfaces guide the components into coaxial alignment during assembly. The curvature of the drive surfaces ensures continuous contact and stable force transmission, eliminating the need for magnetic holding while achieving both alignment and connection stability.
3Manufacturing precision
If drive surfaces are inclined to create a tight fit, then coaxial alignment is improved, but the transition areas become loaded and damage occurs
Solution Approach 1:
The patent carefully controls the inclination angle of the drive surfaces and the relationship between diameters Di and Da to ensure that normal forces are directed tangentially to the drive surfaces rather than into the transition areas. This parameter optimization allows inclined surfaces to provide alignment while protecting transition zones from damaging loads.
Data Source
AI summary
A drive element has an internal driving profile that defines a profile axis (PI) and has, on its inner side, a plurality of concave drive surfaces arranged in a manner distributed regularly around the profile axis (PI), between which a planar or convexly curved transition surfaces are provided, or which has an external driving profile that defines a profile axis (PA) and has, on its outer side, a plurality of concave drive faces arranged in a manner distributed regularly around the profile axis (PA), between which planar or convexly curved transition surfaces are provided. Transitions between the drive surfaces and transition surfaces lie on a common inner circle with an inner diameter Di. The drive surfaces lie on outer circles of an outer diameter Da distributed uniformly around the profile axis.