Screw Anti-Rotation Structure Using Deformation-Based Interference

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Solution Overview

Problem

Existing screw fastening structures face challenges in preventing relative rotation between screws and counterpart members, leading to mechanical loosening and potential shaft fatigue.

Innovation Solution

A relative-rotation prevention structure is implemented, featuring a screw-side deformation-capable section that presses a counterpart-side displacement section using a fastening force, causing deformation and creating a displacement section that prevents relative rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a ratchet structure is employed to prevent relative rotation of female threaded bodies, then relative rotation in loosening direction is restricted, but the structure must be broken to loosen the fastening

Engineering Contradiction:

Improveanti-loosening effectVSAvoidloosening operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The displacement section is divided into multiple segments arranged circumferentially, creating multiple interference points that prevent relative rotation while allowing controlled loosening through systematic engagement disengagement

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The displacement section is formed in advance on the counterpart member, and the deformation-capable section is pre-configured on the screw, so that the anti-loosening function is established before fastening occurs, eliminating the need for breakable ratchet structures

Inventive Principle:

Principle #10Preliminary action

2Reliability

If female threaded bodies act shear force on the male screw shaft permanently, then anti-loosening effect is obtained, but the shaft portion may be fatigued locally and shaft breakage may occur

Engineering Contradiction:

Improveanti-loosening effectVSAvoidshaft strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The mechanical shear force system is replaced with a deformation-based interference system. The deformation-capable section undergoes elastic/plastic deformation to create interference with the displacement section, preventing relative rotation through geometric interference rather than continuous shear force application

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The physical state of the screw portion changes from rigid to temporarily deformable during fastening. The deformation-capable section is designed to undergo controlled deformation under fastening force, changing its dimensional parameters to create interference fit with the displacement section

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a deformation-capable section presses a displacement section using fastening force, then relative rotation is prevented and shaft fatigue is reduced, but the structure complexity increases

Engineering Contradiction:

Improveanti-loosening effectVSAvoidfastening structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The screw structure serves its own anti-loosening function through its deformation-capable section. The fastening force generated during normal tightening operations automatically creates the deformation needed to form the interference pattern with the displacement section, eliminating the need for separate anti-loosening components

Inventive Principle:

Principle #25Self-service

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 structure effectively provides a reliable anti-loosening effect while reducing shaft fatigue and allowing for secure separation of fastening members without damage.

Implementation Method 1

the screw-side deformation-capable section presses the counterpart-side displacement section using a fastening force and thus is deformed

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the screw-side deformation-capable section presses the counterpart-side displacement section using a fastening force and thus is deformed

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 3

axial interference action or axial betrayal action due to the different lead angles and/or lead directions may allow mechanical loosening prevention effect

Methodology Applied

Scientific EffectMechanical interference: Friction

Data Source

PatentUS20250027526A1Relative rotation prevention structure for screw, relative movement prevention structure, and relative movement prevention body

Publication Date: 2025.01.23 NEJILAW

AI summary

A relative rotation prevention structure for preventing relative rotation of a screw having a threaded section with respect to a counterpart member, the relative rotation prevention structure being equipped with: a counterpart-side displacement section formed in advance on the counterpart member and capable of displacement in the axial direction or the radial direction; and a screw-side deformation-capable section that is formed on the screw and deforms when pressed into the counterpart-side deformation section by means of fastening force and, due to that deformation, produces a screw-side displacement section that is displaced in the axial direction or the radial direction.