Plasma Torch Additional Electrode for Non-Conductive Material Cutting

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Solution Overview

Problem

Existing plasma cutting methods are limited in cutting non-conductive materials and materials with poor electrical conductivity, as they require direct electrical connection and suffer from restricted size limitations and poor cutting quality due to nozzle wear.

Innovation Solution

Incorporating an additional electrode guided into the plasma jet, which can be fed and controlled to maintain current flow, allowing for the formation of a pilot arc and main arc for efficient cutting of both conductive and non-conductive materials, with the ability to adjust current and power according to material thickness and type.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If direct plasma cutting method is used with conventional nozzle and electrode arrangement, then cutting of electrically conductive materials is achieved, but cutting of non-conductive materials is not possible

Engineering Contradiction:
Improvematerial type rangeVSAvoidtorch structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

An additional electrode is introduced as an intermediary element between the plasma jet and the workpiece. This additional electrode enables current flow through non-conductive materials by providing an alternative electrical path, allowing the plasma arc to be sustained even when the workpiece itself is electrically insulating.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrical circuit is segmented into multiple paths by introducing the additional electrode. The current can flow through the additional electrode rather than requiring direct contact with the workpiece, separating the functions of plasma generation and electrical circuit completion.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If conventional plasma torch is used for thick materials, then cutting capability is achieved, but cutting speed decreases and nozzle wear increases

Engineering Contradiction:
Improvecutting qualityVSAvoidcutting speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The additional electrode acts as a mediator that absorbs wear and tear from the cutting process. Instead of the nozzle bearing the full brunt of contact with thick materials, the additional electrode serves as the primary contact point, extending nozzle lifespan and maintaining cutting quality at higher speeds.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If high current is used to increase cutting speed, then productivity improves, but nozzle wear increases and material flushing occurs

Engineering Contradiction:
Improvecutting speedVSAvoidnozzle service life
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The additional electrode serves as a sacrificial intermediary that protects the nozzle from direct contact wear. High currents can be applied through the additional electrode without proportionally increasing nozzle wear, enabling sustained high-speed cutting operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The additional electrode functions as a consumable element that can be replaced more easily and cheaply than the nozzle. By directing wear to this sacrificial component, the expensive nozzle is preserved for longer service life.

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

4Reliability

If pilot arc is used to prepare the path, then arc stability improves, but process complexity increases

Engineering Contradiction:
Improvearc stabilityVSAvoidignition system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The additional electrode serves multiple functions: it provides the return path for cutting current through non-conductive materials, acts as a stable arc attachment point, and can function as the cathode or anode depending on operational requirements. This multi-functionality reduces the need for separate pilot arc systems.

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

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

Enables cutting of materials up to 100 mm thick with improved cutting speed and quality, including non-conductive materials like concrete and mixed material combinations, while extending nozzle lifespan and allowing for difficult-to-access workpieces.

Implementation Method 1

Plasma is a thermally highly heated, electrically conductive gas that consists of positive and negative ions, electrons, and excited and neutral atoms and molecules. These gases ionize and dissociate with the energy of the plasma arc.

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 2

For the cutting process, a pilot arc is first ignited between the cathode 2.1 and nozzle 2.2 with a low current

Methodology Applied
Scientific EffectElectric Arc: Electric Arc

Implementation Method 3

This then burns between the electrode 2.1 and the workpiece 4, usually with a larger current (e.g. 20-900A) and thus also with greater power. The workpiece 4 is exposed to the thermal, kinetic and electrical effects of the plasma jet 3.

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 4

The workpiece 4 is exposed to the thermal, kinetic and electrical effects of the plasma jet 3.

Methodology Applied
Scientific EffectKinetic energy transfer: Impact Force

Data Source

PatentEP1919648B1Device and method for the plasma-cutting of workpieces with an additional fusible electrode guided between the nozzle and the workpiece
Publication Date: 2010.10.20 KJELLBERG FINSTERWALDE PLASMA & MASCH GMBH
  • EP1919648B1 patent drawingFigure 1
  • EP1919648B1 patent drawingFigure 2
  • EP1919648B1 patent drawingFigure 3

AI summary

The invention relates to a device and a method for the plasma-cutting of workpieces (4). It can be used for workpieces of different materials, including those which are electrically non-conducting or only poorly conducting. The device according to the invention is formed in such a way that, apart from an electrode (2.1) arranged in a nozzle (2.2) and connected in an electrically conducting manner to an electrical power source (1.1), there is at least one feed (2.3, 2.5) for a gas to the nozzle and a plasma jet (3) is directed at a workpiece, and in addition an additional electrode (7) is guided between the nozzle and the workpiece into the plasma jet.