Tool-Free Fastening Nut With Structured Lateral Surface

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Solution Overview

Problem

Existing screw nuts require tools for fastening, as they lack sufficient frictional engagement with the countersink, leading to the need for constant accessibility and potential loosening during dynamic loads.

Innovation Solution

The screw nut or screw head features a body with a base, top, and lateral surface, where the lateral surface has a surface structure or a truncated pyramid shape to enhance friction, and a countersink design that allows tool-free fastening by leveraging frictional torque and elastic deformation to prevent rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a smooth lateral surface is used on the screw nut, then the manufacturing process is simple, but the friction between the nut and component is insufficient, requiring tools for fastening

Engineering Contradiction:
Improvetool-free fasteningVSAvoidsurface structure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The lateral surface of the screw nut is provided with a surface structure (such as knurling, grooves, or protrusions) only in the region that contacts the component, while other regions maintain smooth surfaces. This localized application of surface structure increases friction where needed without unnecessarily complicating the entire nut geometry or manufacturing process

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The lateral surface is divided into different zones: a first region with a surface structure for friction engagement with the component, and a second region with a smooth surface. This segmentation allows the nut to provide both tool-free fastening capability and simplified manufacturing for non-critical areas

Inventive Principle:
Principle #1Segmentation

2Reliability

If a prismatic outer contour with tool access recesses is used, then tools can be applied to tighten the nut, but the nut requires constant accessibility and may loosen under dynamic loads

Engineering Contradiction:
Improveresistance to looseningVSAvoidaccessibility requirement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The surface structure on the lateral surface enables the screw nut to self-lock against the component through friction engagement. When the screw is tightened, the friction force generated between the structured lateral surface and the component prevents the nut from rotating loose, allowing the nut to secure itself without requiring constant tool intervention or accessibility for maintenance

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The surface structure is designed to generate frictional torque that counteracts the tightening torque and prevents rotation before loosening can occur. This preliminary frictional engagement acts as a preventive measure against loosening under dynamic loads, eliminating the need for subsequent tool intervention

Inventive Principle:
Principle #9Preliminary anti-action

3Ease of operation

If the base surface is not smooth, then friction with the component increases, but the flush surface quality deteriorates

Engineering Contradiction:
Improvefriction engagementVSAvoidflush surface quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The surface structure is applied only to a specific region of the lateral surface that contacts the component, while the base surface remains smooth to ensure proper flush mounting. This localized differentiation allows the friction-enhancing surface structure to be present where needed without compromising the overall flush surface quality between the nut base and the component

Inventive Principle:
Principle #3Local quality

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 tool-free fastening and prevents unintentional loosening, ensuring secure attachment without the need for tools, even under dynamic loads.

Implementation Method 1

the lateral surface has, at least in some areas, a surface structure suitable for achieving a predetermined friction in conjunction with a predetermined area of the component, wherein this friction is greater than that of a smooth lateral surface

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

leveraging frictional torque and elastic deformation to prevent rotation

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3987188B1Fastening assembly and method for production
Publication Date: 2026.01.14 FURSTENBERG MALTE
  • EP3987188B1 patent drawingFigure 1a~1b
  • EP3987188B1 patent drawingFigure 2~3
  • EP3987188B1 patent drawingFigure 4a~4b

AI summary

The invention relates to a nut (1) for fastening a component (12). The nut (1) comprises a body (2), which is formed by a base surface (3), a top surface (4) and a peripheral surface (6) extending between them. A surface area of the base surface (3) is greater than a surface area of the top surface (4). The peripheral surface (6) comprises, at least in some regions, a surface structure which is suitable for achieving a defined friction in co-operation with a defined surface of the component (12) which is greater than a friction with a smooth surface. The base surface (3) has a substantially smooth surface. The body (2) comprises a bore (8), which extends from the top surface (4) at least partially between top surface (4) and base surface (3) and has an internal thread (10) of defined size.