Bolt Anchor Thread Overhang for Cap Nut Expansion Control

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Solution Overview

Problem

Existing methods for setting bolt anchors in anchor holes often require a nut to be screwed onto the fastening thread to control and limit the expansion of the anchor, which can be aesthetically unappealing and pose a risk of injury, and there is a need for a method that allows for efficient anchoring without this requirement.

Innovation Solution

The method involves inserting a bolt anchor with an expansion body and sleeve into an anchor hole without a nut, where the anchor shaft is positioned deep enough for the fastening thread to protrude, allowing a cap nut to be placed later to exert a tensile force on the expansion body, expanding the sleeve and anchoring the anchor by force or form fit, with the overhang of the fastening thread determined by the attachment and other parts to ensure proper engagement and expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a nut is screwed onto the fastening thread to control and limit the expansion of the anchor, then the anchoring function is achieved, but the aesthetic appearance deteriorates and the risk of injury increases

Engineering Contradiction:
Improveanchoring functionVSAvoidaesthetic appearance and injury risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the nut from the final assembled state by using a cap nut with a blind hole that limits screwing depth. The anchoring function is achieved through the expansion body and expansion sleeve mechanism, while the cap nut serves only as a protective cover without the need for a traditional nut, thereby eliminating the harmful visual and safety effects.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a cap nut with a blind hole as an intermediary component that mediates between the fastening thread and the expansion body. The blind hole depth controls the expansion limit, allowing the cap nut to serve both as a protective cover and as a mechanism to limit expansion, replacing the need for a traditional nut.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the anchor is inserted without a nut initially, then the aesthetic appearance and safety are improved, but the control and limitation of expansion becomes more difficult

Engineering Contradiction:
Improveaesthetic appearance and injury riskVSAvoidcontrol and limitation of expansion
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The cap nut with a blind hole serves as an intermediary that provides controlled limitation of expansion. The blind hole depth is designed to correspond to the required expansion length, automatically limiting the expansion when the cap nut is screwed onto the fastening thread, thus maintaining ease of operation while achieving aesthetic and safety goals.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter of the cap nut by introducing a blind hole with a specific depth. This parameter change allows the cap nut to automatically limit the expansion of the anchor when screwed onto the fastening thread, providing controlled expansion limitation without requiring initial nut installation.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the fastening thread protrudes too far from the anchor hole, then the cap nut can be easily installed, but the expansion length is insufficient

Engineering Contradiction:
Improvecap nut installationVSAvoidexpansion length
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The patent precisely controls the parameter of the fastening thread protrusion length. The protrusion length is designed to be sufficient for cap nut installation but not excessive, ensuring that when the cap nut is screwed on, the expansion body can achieve the required expansion length while the cap nut's blind hole provides automatic limitation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cap nut with a blind hole provides feedback control for the expansion process. When the cap nut is screwed onto the fastening thread, the blind hole depth provides a physical stop that feedbacks the maximum expansion length, ensuring sufficient expansion while preventing over-expansion.

Inventive Principle:
Principle #23Feedback

4Length of moving object

If the fastening thread protrudes too little from the anchor hole, then the expansion length is sufficient, but the cap nut cannot be properly installed

Engineering Contradiction:
Improveexpansion lengthVSAvoidcap nut installation
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

The patent optimizes the parameter of the fastening thread protrusion length to a precise value that satisfies both requirements. The protrusion length is calculated to be exactly sufficient for cap nut installation while ensuring the expansion body can achieve the required expansion length when the cap nut is installed.

Inventive Principle:
Principle #35Parameter changes

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 method allows for efficient anchoring without the need for an initial nut, providing a secure and aesthetically acceptable solution by determining the overhang of the fastening thread based on the attachment and cap nut dimensions, ensuring effective expansion and anchoring while minimizing the risk of injury.

Implementation Method 1

a tensile force can then be exerted on the expansion body via the anchor shank, which pulls the expansion body into the expansion sleeve

Methodology Applied
Scientific EffectTensile force: Tension

Implementation Method 2

The anchoring can be done by force fit and/or form fit of the expansion sleeve in the anchor hole

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3330550B1Method for setting an anchor in an anchor hole in an anchoring base
Publication Date: 2021.07.28 FISCHERWERKE ARTUR FISCHER GMBH & CO KG
  • EP3330550B1 patent drawingFigure 1~2
  • EP3330550B1 patent drawingFigure 3~4

AI summary

The invention proposes to insert an anchor (1) with a projection (L) into an anchor hole (7) which ensures thread engagement of a hand-fitted cap nut (12) and prevents the anchor (1) from bumping against the cap nut (12) when tightening.