Robot Cable Inner Outer Core Segmentation for Torsion Fatigue

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Industrial robot cables face durability and fatigue issues due to repeated torsion and bending, leading to frequent conductor breaks and significant downtime and costs in production environments.

Innovation Solution

A cable design featuring inner and outer cores with specific twisting pitches, unsintered fluororesin binding tapes, and elastic yarn inserts to manage stress and friction, ensuring a low coefficient of friction and controlled yield strength increase, thereby enhancing durability and fatigue life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cable structures are used in industrial robots, then the cable can transmit power and signals, but the cable suffers from conductor breakage due to repeated torsion and bending fatigue

Engineering Contradiction:
Improvecable durabilityVSAvoidcable fatigue life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The cable is divided into multiple independent cores (inner cores and outer cores), each containing conductors that can move independently. This segmentation allows each conductor to accommodate torsion and bending stresses separately, preventing stress concentration and conductor breakage, thereby improving cable durability and fatigue life under repeated mechanical loads

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cable employs composite material structures including conductors with specific material compositions, insulating layers, binding tapes, and protective sheaths. The conductors use materials with optimized mechanical properties to resist fatigue, while the composite structure allows differential movement between layers, reducing stress on individual conductors during torsion and bending cycles

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If the cable structure is simplified to reduce manufacturing complexity, then production costs decrease, but the cable's ability to withstand repeated torsion and bending is reduced

Engineering Contradiction:
Improvecable manufacturing complexityVSAvoidcable durability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The cable is divided into modular segments including inner cores, outer cores, binding tapes, and sheaths. Each module can be manufactured independently using standardized processes, then assembled systematically. This modular segmentation maintains manufacturing simplicity while enabling the complex stress-distribution architecture needed for high durability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cable incorporates dynamic elements such as flexible binding tapes and movable core structures that adapt to mechanical stresses in real-time. These dynamic components allow the cable to self-adjust during torsion and bending, distributing loads effectively without requiring complex pre-engineered rigid structures, thus maintaining ease of manufacture while improving reliability

Inventive Principle:
Principle #15Dynamics

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 cable exhibits significantly increased durability and fatigue life, minimizing process interruptions and associated losses by effectively managing torsion and bending stresses, with resistance change rates remaining low even after extensive use.

Implementation Method 1

an inner binding tape and an outer binding tape which bind the inner cores and the outer cores, respectively, and are formed of an unsintered fluororesin and have a coefficient of friction in a range of 0.05 to 0.2

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the first insert and the second insert are formed by twisting elastic yarn, respectively

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3633692B1Cable for robot
Publication Date: 2023.07.26 LS CABLE & SYST LTD
  • EP3633692B1 patent drawingFigure 1
  • EP3633692B1 patent drawingFigure 2~3
  • EP3633692B1 patent drawingFigure 4~5

AI summary

The present invention relates to a cable, for a robot, which has significantly improved durability against repeated torsion and a long bending life and thus is applicable as an industrial robot.