Contact Start Plasma Arc Torch Electrode for Wear and Alignment

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Solution Overview

Problem

Contact start plasma arc torches face issues with component wear and misalignment, leading to reduced productivity and accuracy due to the need for frequent replacement of consumable parts, particularly the power contact, which is not designed to be easily replaceable and requires disassembly, and the stiffness of the power cable affecting torch maneuverability.

Innovation Solution

An electrode with a resilient conductive element that facilitates both pilot arc current passage and mechanical movement, reducing wear on components and allowing for alignment during operation, while a dual-function design minimizes the need for consumable parts and simplifies the torch design by integrating electrical and mechanical functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the power contact is made stationary relative to the torch body, then the cable stiffness issue is resolved, but the electrode alignment and arc initiation effectiveness are affected

Engineering Contradiction:
Improvetorch maneuverabilityVSAvoidarc initiation effectiveness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The power contact is segmented into two functional parts: a stationary contact element fixed to the torch body and a movable contact element attached to the electrode assembly. This segmentation allows the stationary part to provide stable electrical connection while the movable part enables electrode alignment through movement, resolving the contradiction between maneuverability and arc initiation effectiveness

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A resilient conductive element acts as an intermediary between the stationary power contact and the movable electrode. This intermediary component facilitates relative movement while maintaining electrical continuity, allowing the electrode to move for alignment purposes while the power contact remains stationary, thus resolving the contradiction

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the power contact moves with the electrode during pilot arc initiation, then arc initiation is effective, but wear on the power contact increases and it requires frequent replacement

Engineering Contradiction:
Improvearc initiation effectivenessVSAvoidpower contact lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The power contact system is segmented into a stationary contact element that remains fixed during operation and a movable electrode assembly. This segmentation ensures that only the consumable electrode moves and wears, while the non-consumable power contact remains stationary and durable, extending its lifespan while maintaining effective arc initiation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electrode is designed as a disposable consumable component that absorbs all wear during movement and arc initiation. By making the electrode replaceable and inexpensive relative to the power contact, the system allows frequent electrode replacement without replacing the durable stationary power contact, thus extending the overall system lifespan

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

3Reliability

If the electrode moves away from the nozzle to initiate pilot arc, then arc formation is achieved, but misalignment of consumable components occurs reducing accuracy

Engineering Contradiction:
Improvearc formation capabilityVSAvoidplasma jet location accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The electrode assembly is designed with dynamic movement capability along the longitudinal axis, allowing it to move away from the nozzle during pilot arc initiation and return to its precise operational position. This controlled dynamic movement enables reliable arc formation while maintaining manufacturing precision through proper positioning mechanisms

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The electrode is pre-positioned in a retracted position away from the nozzle before arc initiation. This preliminary positioning allows the pilot arc to form without affecting the final plasma jet location accuracy, as the electrode returns to its precise operational position after arc initiation

Inventive Principle:
Principle #10Preliminary action

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 extends the lifespan of torch components, reduces wear, and enhances operational accuracy and productivity by minimizing the need for frequent replacements and improving the flexibility of the torch system.

Implementation Method 1

a resilient conductive element for conducting current from the power contact to the electrode body during pilot arc operation

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The resilient element comprises an electrically conductive material to facilitate both carrying a pilot arc current and dissipating thermal heating associated with the pilot arc current

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

The separation causes an arc to be formed between the electrode and the nozzle in the plasma chamber. The arc ionizes the introduced gas to produce a plasma jet

Methodology Applied
Scientific EffectIonization: Ionisation

Data Source

PatentEP3454627B1Assembly for a contact start plasma arc torch
Publication Date: 2023.12.13 HYPERTHERM INC
  • EP3454627B1 patent drawingFigure 1
  • EP3454627B1 patent drawingFigure 2A~2C
  • EP3454627B1 patent drawingFigure 3A~3B

AI summary

An electrode for a contact start plasma arc torch includes an elongated electrode body formed of an electrically conductive material. The electrode body is movable relative to the torch. A resilient element is used for passing substantially all of a pilot arc current between a power supply, a power connection in electrical communication with the power supply, and the electrode body during pilot arc operation of the plasma arc torch. The electrode and torch can include a contact element having a first surface in electrical communication with the power contact and a second surface for physical contact and electrical communication with a corresponding contact surface of the electrode body for passing substantially all of a transferred arc current between the power supply and the electrode body during transferred arc mode.