Zero-Protrusion Shearable Fastener Bolt for Electric Wire Clamping

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Solution Overview

Problem

Existing shearable fastener bolts for electric wires fail to guarantee zero protrusion and require varying tightening torques for different wire diameters, leading to potential damage and inefficient clamping.

Innovation Solution

A fastener bolt design with two breaking points, utilizing a shearable bolt part and a nut part, where the head section breaks at a predetermined fastening torque and the thread section breaks at a tensile breaking strength, ensuring minimal protrusion and consistent clamping force across various wire diameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single predetermined breaking point is used in existing shearable fastener bolts, then the bolt can be designed to break at a specific location, but zero protrusion cannot be guaranteed and the break may occur in the threaded portion weakening the connection

Engineering Contradiction:
Improvebreaking point location precisionVSAvoidconnection strength
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The fastener bolt is divided into two distinct breaking point locations: a first breaking point in the non-threaded portion and a second breaking point in the threaded portion. This segmentation ensures that the bolt breaks in a controlled manner at the first breaking point during normal operation, preventing zero protrusion issues, while the second breaking point serves as a backup to maintain connection strength if the first breaking point fails.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The design incorporates a backup breaking point mechanism that cushions against the risk of improper breaking. If the first breaking point does not achieve zero protrusion or fails to break, the second breaking point in the threaded portion will break under excessive load, preventing complete connection failure and maintaining system reliability.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Device complexity

If a single predetermined breaking point is used in existing shearable fastener bolts, then the design is simple, but the tightening torque must be larger for small diameter wires compared to large diameter wires

Engineering Contradiction:
Improvefastener bolt design simplicityVSAvoidapplicability across different wire diameters
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The fastener bolt with dual breaking points is designed to be universally applicable across different wire diameters. The first breaking point in the non-threaded portion allows consistent torque application for various wire sizes, while the second breaking point in the threaded portion provides a safety mechanism. This multi-functional design eliminates the need to adjust torque values for different wire diameters, enhancing adaptability while maintaining reasonable design complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Length of stationary object

If the fastener bolt is designed to break at a predetermined torque, then protrusion is minimized, but the wire or connector may be damaged if the torque becomes too high or too low

Engineering Contradiction:
Improveprotrusion lengthVSAvoidwire and connector damage
Core Design Contradiction:
Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The dual breaking point design cushions against torque-related damage by providing a backup failure mode. The first breaking point in the non-threaded portion is designed to break at the intended torque, minimizing protrusion. However, if the torque is too high and causes damage, or too low and fails to break, the second breaking point in the threaded portion provides a safety mechanism that prevents catastrophic failure of the wire or connector by breaking instead.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The fastener bolt is designed as a disposable component with sacrificial breaking points. The first breaking point in the non-threaded portion is intended to break during normal operation, sacrificing the bolt itself to protect the wire and connector. The second breaking point provides an additional sacrificial element that prevents damage if the first breaking point fails to protect the system.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 design provides secure, zero-protrusion clamping with consistent torque requirements, preventing damage to wires and connectors, and allowing for efficient application across a range of wire diameters.

Implementation Method 1

The fastener bolt (1) comprises a head section (8) and a threaded section (6)... a first breaking point (40) between the head section (8) and the threaded section (6)... when a fastening torque is applied, the fastener bolt breaks at the first breaking point (40)

Methodology Applied
Scientific EffectShear stress: Shear Stress

Implementation Method 2

a second breaking point (104) in the threaded section (6)... when a fastening torque is applied, the fastener bolt breaks at the second breaking point (104)

Methodology Applied
Scientific EffectTensile stress: Tension

Data Source

PatentEP3388697B2Shearable fastener bolt and method for clamping electric wires, and electric connector comprising a zero-protrusion shearable fastener
Publication Date: 2025.08.20 TYCO ELECTRONICS SIMEL
  • EP3388697B2 patent drawingFigure 1~3
  • EP3388697B2 patent drawingFigure 4~6
  • EP3388697B2 patent drawingFigure 7~8

AI summary

The invention relates to a fastener bolt (1), an electric connector (70) and a method for clamping an electric wire (80). The fastener bolt (1) is provided with a shearing section (40). Due to the shearing section (40), a head section (8) of the fastener bolt (1) is sheared off automatically when the fastener bolt (1) is tightened against the electric wire (80) and a predetermined fastening torque (84) is exceeded. A thread section (6) of the fastener bolt (1) is hollow and has a predetermined tensile break strength. Once the head section (8) is sheared off, a nut part (4), which is screwed onto the thread section (6), is tightened against a wall (74) having a threaded hole (72), into which the fastener bolt (1) is screwed. By tightening the nut part (4) against the wall (74), a tensile stress (92) is generated in the thread section (6) between the nut part (4) and the threaded hole (72). When the tensile stress (92) exceeds the predetermined tensile break strength, the thread section (6) will break right above the threaded hole (72). The usage of the nut part (4) for breaking the thread section (6) directly above the threaded hole (72) ensures that the remaining thread section (6) does not protrude much from the threaded hole (72). This reduces the danger of injuries or damage to head shrink tubes by sharp edges of the broken section (6).