Helical Cable With Urethane Sheath For SCARA Robot Deflection

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Solution Overview

Problem

Cables in SCARA robots, when subjected to high-speed movements, experience excessive deflection and are prone to wire breaks due to stress concentration at terminal sections, and enlarging the bush to prevent this restricts design flexibility and motion.

Innovation Solution

A cable design featuring electric wires laid helically around a central core with a urethane resin inner sheath and a protective outer sheath, or a core member with a resin coating, to enhance resistance to deflection and breakage during high-speed movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bush is enlarged to cover the cable periphery, then wire break resistance is improved, but design flexibility and cable motion flexibility are worsened

Engineering Contradiction:

Improvewire break resistanceVSAvoiddesign flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The cable structure is segmented into multiple functional layers: core members for structural support, helically laid electric wires for flexibility, inner sheath for protection, and outer sheath for environmental resistance. This segmentation allows each layer to perform its specific function optimally without requiring an oversized bush.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cable employs composite material construction with different materials serving different purposes: the core member provides rigidity, the urethane resin inner sheath provides elasticity and stress distribution, and the outer sheath provides environmental protection. This composite structure achieves wire break resistance without increasing overall cable diameter.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the bush is enlarged to cover the cable periphery, then wire break resistance is improved, but cable motion flexibility is worsened

Engineering Contradiction:

Improvewire break resistanceVSAvoidcable motion flexibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The cable incorporates dynamic elements including helically laid electric wires that can rotate and flex, and an elastic core member that can deform under stress. This dynamic structure allows the cable to flex and move freely during high-speed arm movements while maintaining wire break resistance through its layered construction.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cable utilizes parameter changes in material properties: the urethane resin inner sheath provides elasticity to absorb stress during motion, while the outer sheath provides rigidity for protection. This combination of soft and hard parameters allows the cable to be both flexible in motion and resistant to wire breakage.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If the cable is routed in an arch shape over movable parts, then space utilization is improved, but deflection resistance is worsened during high speed movement

Engineering Contradiction:

Improvespace utilizationVSAvoiddeflection resistance

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The cable structure incorporates beforehand cushioning through the elastic urethane resin inner sheath and the helically laid wire construction. These elements are designed to absorb and distribute stress before it can cause excessive deflection or wire breakage during high-speed movements, allowing the cable to maintain its arch shape while resisting deflection.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 maintains its shape and resists deflection and breakage even at high speeds without increasing diameter or mass, ensuring flexibility and reliability in motion.

Implementation Method 1

the sheath includes an inner layer sheath comprising a urethane resin

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a core member comprising a resin and being provided in a center of the cable

Methodology Applied

Scientific EffectRigidity:

Implementation Method 3

an outer layer sheath provided around an outer periphery of the inner layer sheath to protect the inner layer sheath

Methodology Applied

Scientific EffectPhysical protection:

Data Source

PatentUS11011286B2Cable

Publication Date: 2021.05.18 PROTERIAL LTD

AI summary

A cable includes a plurality of electric wires, which are laid helically around a center of the cable and along a central axis of the cable, and a sheath provided to cover respective peripheries of the plurality of electric wires together. The sheath includes an inner layer sheath made of a urethane resin, and an outer layer sheath provided around an outer periphery of the inner layer sheath to protect the inner layer sheath. The cable may further include a core member at its center. The sheath may be composed of a single layer instead of plural layers.