Shearing Screw Thread Impediment for Controlled Conductor Clamping

Solution Overview

Problem

Existing shearing screws for clamping electrical conductors in cable connectors face challenges in ensuring correct shearing, clamping force control, and durability, often leading to damage to the cable or connector materials.

Innovation Solution

A shearing screw design with modified threads allows for separate tightening and shearing steps, featuring a tightener with an inner thread and outer thread impediment to control friction and clamping force, enabling controlled clamping and efficient shearing without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the screw is made longer to ensure proper clamping, then the clamping reliability is improved, but the risk of damaging covering material increases

Engineering Contradiction:

Improveclamping reliabilityVSAvoiddamage to covering material

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The screw is divided into two functional segments: a first body for clamping the electrical conductor and a second body (tightener) for applying and controlling the clamping force. This segmentation allows the clamping function to be separated from the force application function, enabling precise control of the screw length engaged in clamping without excessive length causing damage to covering material.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The thread pitch is changed between the first and second bodies: the first body has a first thread pitch optimized for clamping, while the second body has a second thread pitch optimized for force application. This parameter change allows the tightener to rotate multiple times per unit of linear advancement, providing mechanical advantage and precise control over the clamping force while limiting the total screw engagement length.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the screw is made shorter to avoid damaging covering material, then the harm to covering material is reduced, but the risk of screw detachment increases

Engineering Contradiction:

Improvedamage to covering materialVSAvoidscrew retention

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The screw is divided into two functional segments: a first body for clamping the electrical conductor and a second body (tightener) for applying and controlling the clamping force. This segmentation allows the clamping function to be separated from the force application function, enabling precise control of the screw length engaged in clamping without excessive length causing damage to covering material.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connection between the first and second bodies is made dynamic through the threaded interface with an impediment. The impediment allows relative rotation during the tightening process while preventing detachment after tightening. This dynamic connection enables the screw to transition from a state where parts can move relative to each other (during installation) to a state where they are securely locked (after installation).

Inventive Principle:

Principle #15Dynamics

3Reliability

If the clamping force is increased to prevent cable escape, then the cable retention is improved, but the risk of cable damage increases

Engineering Contradiction:

Improvecable retentionVSAvoidcable damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The thread pitch is changed between the first and second bodies: the first body has a first thread pitch optimized for clamping, while the second body has a second thread pitch optimized for force application. This parameter change allows the tightener to rotate multiple times per unit of linear advancement, providing mechanical advantage and precise control over the clamping force while preventing both cable escape and cable damage.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The impediment in the threaded connection provides feedback control for the clamping force. As the tightener rotates and applies force, the impediment engages to prevent over-tightening, creating a natural feedback mechanism that stops the tightening process at the optimal clamping force, thereby preventing cable damage while ensuring adequate retention.

Inventive Principle:

Principle #23Feedback

4Device complexity

If a single-thread design is used to simplify the structure, then the device complexity is reduced, but the ability to control clamping force and shearing separately is lost

Engineering Contradiction:

Improvescrew structure complexityVSAvoidcontrolled clamping and shearing

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The screw is divided into two functional segments: a first body for clamping the electrical conductor and a second body (tightener) for applying and controlling the clamping force. This segmentation allows the clamping function to be separated from the force application function, enabling precise control of the screw length engaged in clamping without excessive length causing damage to covering material.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tightener and the shearing screw are combined into a single integrated component with a unified body structure. The tightener includes both the outer thread for engaging the cable connector and the inner thread for engaging the shearing screw, merging multiple functions into one component while maintaining the ability to control clamping force and shearing separately through the threaded interface.

Inventive Principle:

Principle #5Merging (Combining)

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 solution ensures precise clamping force and controlled shearing, reducing the risk of damage to cables or connectors, while allowing for easy installation and removal, enhancing durability and reliability in electrical grid applications.

Implementation Method 1

The impediment may be adapted to increase the static friction between the tightener and the shearing screw so that their relative movement is prevented or hindered throughout the tightening of the shearing screw

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3454421B1Shearing screw and use thereof

Publication Date: 2023.08.23 OY ENSTO AB

AI summary

The disclosure relates to a shearing screw (130) for clamping an electrical conductor (200) within a cable connector (100). The shearing screw (130) comprises a first body (140) having an outer thread (150) for engaging the cable connector (100), a clamping surface (146) for clamping the electrical conductor (200) within the cable connector (100) and a tightener (160) for fastening the shearing screw (130) to the cable connector (100) and for shearing the shearing screw (130). The tightener (160) further comprises a second body (162) having an inner thread (180) for engaging the outer thread (150) of the first body (140) and a bearing surface (170) for engaging the cable connector (100) so that a tensile force is introduced in the shearing screw (130) for shearing the shearing screw (130). A region of the inner thread (180) or a region of the outer thread (150) is adapted to form an impediment for preventing or hindering relative movement between the first body (140) and the tightener (160).