Curved Screw Drive Profiles for Coaxial High-Torque Engagement

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Solution Overview

Problem

Existing screw and turning tool connections often suffer from unintentional detachment and misalignment, leading to damage from excessive torque, especially in automated processes, due to the play between complementary driving profiles.

Innovation Solution

The method employs driving profiles with inclined, concave or convex surfaces that come into contact on both sides of the apex when plugged together, avoiding contact in transition areas to create a non-positive clamping connection, ensuring coaxial alignment and high torque transmission without damaging the edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional complementary driving profiles are used, then torque transmission is achieved, but play between profiles causes unintentional detachment and misalignment

Engineering Contradiction:
Improveconnection stabilityVSAvoidcoaxial alignment precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The driving profiles utilize curved surfaces instead of flat surfaces. The outer driving profile has a concave curved surface while the inner driving profile has a convex curved surface, allowing them to mate together. This curvature eliminates play between the profiles while maintaining torque transmission capability, preventing unintentional detachment and ensuring precise coaxial alignment.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If magnetic turning tools are used to prevent detachment, then holding force is improved, but additional effort and complexity are required

Engineering Contradiction:
Improveconnection stabilityVSAvoidtool complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The driving profiles are designed to self-align and self-lock through their complementary curved geometry. The concave-convex mating surfaces automatically guide the components into coaxial alignment and maintain a secure connection without requiring external magnetic fields or additional holding mechanisms, eliminating the complexity of magnetic turning tools.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If play between driving profiles is present, then assembly is easier, but edge damage occurs under excessive torque

Engineering Contradiction:
Improveassembly easeVSAvoidedge strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The curved mating surfaces of the driving profiles distribute contact forces across a larger area and guide the components into proper alignment during assembly. This eliminates edge concentration of stresses that leads to damage under torque, while the smooth curved geometry facilitates easy insertion and assembly.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Ease of manufacture

If flat drive surfaces are used, then manufacturing is simpler, but coaxial alignment cannot be achieved

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcoaxial alignment precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The curved surfaces are designed with specific radii that can be manufactured using standard machining operations. The concave surface of the outer profile and the convex surface of the inner profile are complementary, allowing them to mate precisely. This curvature inherently guides the components into coaxial alignment while remaining manufacturable with conventional techniques.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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

This design allows for secure, rotation-proof connections with precise coaxial alignment and high torque transmission, preventing edge damage and enabling use in automated processes.

Implementation Method 1

the inclined drive surfaces of the components come into surface contact with one another when the components are axially plugged together, so that the interaction of the driving profiles creates a force-locking connection and/or clamping connection between the components

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3807544B1Method for connecting two components for conjoint rotation
Publication Date: 2024.12.11 BONGARTZ NICOLE
  • EP3807544B1 patent drawingFigure 1
  • EP3807544B1 patent drawingFigure 2
  • EP3807544B1 patent drawingFigure 3

AI summary

The invention relates to a method for connecting a screw (1) and a rotary tool (8) for conjoint rotation, wherein the drive surfaces (6, 10) of the drive profiles (5, 9) have a constant inclination with respect to their profile axis (PA, PI) which is the same for all drive surfaces of both components (1, 8). In the component comprising the outer drive profile (5), the drive surfaces (6) are all concave or all convex, and in the component comprising the inner drive profile (9), the drive surfaces (10) are curved so as to be complementary to the drive surfaces (6) of the outer drive profile (5) such that, in the assembled state, the drive surfaces (6, 10) of the two components (1, 8), as viewed in the peripheral direction, come into flat contact/engagement with one another on both sides of the apex of the concave/convex curvature. The drive profiles (5, 9) are designed such that they do not come into contact with one another in the transition regions between the drive surfaces (6, 10).