Cable With Hollow Tubes For Discharge Stability

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Solution Overview

Problem

In wire electrical discharge machines, the capacitance between the conductor and the dielectric working fluid leads to unstable discharge due to electrostatic coupling, especially at higher frequencies, causing leakage issues.

Innovation Solution

A cable design featuring a linear conductor surrounded by hollow resin tubes forming an air layer, which reduces capacitance by creating a gap between the conductor and the working fluid, and an insulating protective member to prevent contact and further minimize capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the cable conductor is directly immersed in the dielectric working fluid, then the cable structure is simple, but capacitance between the conductor and working fluid increases causing leakage and unstable discharge

Engineering Contradiction:
Improvecable structureVSAvoiddischarge stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces an intermediary insulating layer between the conductor and the dielectric working fluid. This insulating layer acts as a mediator that prevents direct contact between the conductor and working fluid, thereby reducing capacitance and electrostatic coupling while maintaining the cable's functional simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cable structure is segmented into distinct layers: the conductor, the insulating layer, and the outer protective layer. This segmentation isolates the conductor from the working fluid through the insulating layer, reducing capacitance effects while maintaining structural organization and simplicity.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If AC voltage at high frequency is applied to avoid workpiece corrosion, then corrosion resistance is improved, but leakage due to electrostatic coupling increases causing unstable discharge

Engineering Contradiction:
Improveworkpiece corrosionVSAvoiddischarge stability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The insulating layer serves as a mediator that blocks electrostatic coupling between the conductor and working fluid. This allows high-frequency AC voltage to be applied for corrosion prevention while the insulating layer prevents the capacitance effects that would otherwise cause leakage and discharge instability at these frequencies.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical parameters of the cable system by introducing the insulating layer, which modifies the capacitance and impedance characteristics. This enables the system to operate at high frequencies for corrosion prevention without suffering from the increased leakage that would normally occur at these frequencies.

Inventive Principle:
Principle #35Parameter changes

3Power

If the surface area of the cable in contact with the working fluid is increased, then voltage application capability is improved, but leakage due to electrostatic coupling worsens

Engineering Contradiction:
Improvevoltage application capabilityVSAvoidleakage
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The insulating layer acts as a mediator that allows the cable to have increased surface area for voltage application while preventing electrostatic coupling. The insulating material enables the conductor to maintain a larger effective surface area without proportionally increasing capacitance to the working fluid, thus reducing leakage losses.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 air layer significantly reduces capacitance between the conductor and the working fluid, minimizing leakage and stabilizing the discharge process, even at higher frequencies.

Implementation Method 1

the air layer significantly reduces capacitance between the conductor and the working fluid, minimizing leakage and stabilizing the discharge process

Methodology Applied
Scientific EffectCapacitance reduction through air layer isolation: Capacitance

Data Source

PatentEP3514804B1cable
Publication Date: 2022.03.02 FANUC LTD
  • EP3514804B1 patent drawingFigure 1
  • EP3514804B1 patent drawingFigure 2
  • EP3514804B1 patent drawingFigure 3

AI summary

A cable (10) includes: a linear conductor (12); a plurality of resin hollow tubes (16) which are disposed around the conductor (12) so that an air layer is formed around the conductor (12) and which extend in a longitudinal direction of the conductor (12); and an insulating protective member (14) configured to protect the conductor (12) and the plurality of hollow tubes (16).