Bolt Head Opening Structure for Fastening Detection and Anti-Loosening

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Solution Overview

Problem

Conventional bolts require a minimum height for the tool coupling recess, leading to a thick threaded part, making them prone to unintentional loosening and preventing visual detection of fastening state due to tool accommodation.

Innovation Solution

A bolt design with openings in the coupling recess allowing tool exposure, featuring an inclined accommodation portion and anti-loosening protrusions to reduce head height, enable fastening detection, and prevent loosening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the tool coupling recess is extended to the threaded part, then the height of the head part can be reduced, but the thickness of the threaded part must be increased

Engineering Contradiction:
Improveheight of head partVSAvoidthickness of threaded part
Core Design Contradiction:
Length of moving objectVSLength of stationary object

Solution Approach 1:

The coupling recess is designed to extend through the head part into the threaded part, utilizing the depth dimension to accommodate the tool. This allows the tool coupling function to be achieved without increasing the head height, as the recess utilizes the vertical depth of the threaded part instead of requiring additional horizontal or vertical head dimensions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The coupling recess is nested within the threaded part structure, with the recess extending through the head part and into the threaded part. This nesting allows the tool accommodation space to be integrated within the existing bolt geometry, eliminating the need for separate tool coupling structures that would increase overall dimensions.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If the tool is completely accommodated in the tool coupling recess, then stable coupling is achieved, but the fastening state cannot be detected

Engineering Contradiction:
Improvestable couplingVSAvoidfastening state detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

A portion of the tool is extracted from complete accommodation within the recess and exposed through the opening in the head part. This allows the tool to remain sufficiently engaged for stable coupling while simultaneously providing visual access to the tool's position and orientation, enabling detection of the fastening state.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The head part is designed with an opening that creates a porous or permeable structure, allowing visual penetration through the head to observe the tool. This opening maintains structural integrity while enabling optical access to the tool coupling state, solving the detection problem without compromising coupling stability.

Inventive Principle:
Principle #31Porous materials

3Ease of operation

If the head part cannot be fixed to the structure, then the threaded part can be fastened, but unintentional loosening occurs due to vibration or shock

Engineering Contradiction:
Improvefastening operationVSAvoidresistance to loosening
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The opening in the head part serves as a preliminary anti-loosening mechanism by allowing the insertion of a locking element or adhesive. This preliminary action prevents the harmful effect of vibration-induced loosening before it occurs, maintaining the fastened state through subsequent vibration or shock events.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The opening acts as an intermediary pathway that enables the introduction of additional fastening elements such as lock washers, adhesives, or retaining compounds. These intermediary substances or components are introduced through the opening to secure the head part to the structure, preventing unintentional loosening while maintaining ease of initial fastening operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4151868B1Bolt having opening
Publication Date: 2025.12.24 BOLTS ONE CO LTD
  • EP4151868B1 patent drawingFigure 1
  • EP4151868B1 patent drawingFigure 2
  • EP4151868B1 patent drawingFigure 3

AI summary

Proposed herein is a bolt that includes a head part and a threaded part and is fastened to a structure through the threaded part while being rotated by a tool. The bolt further includes: a coupling recess formed in the head part or the threaded part while forming a recess shape having a cross section corresponding to that of the tool, and configured to allow the tool to be coupled thereto; and one or more openings formed in portions of the coupling recess in hole shapes, and configured to expose at least portions of the tool, coupled to the coupling recess, out of the head part or the threaded part.