Plasma Cutting Torch Piercing Current Control

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Solution Overview

Problem

Conventional plasma cutting systems are limited in cutting thickness due to the thermal capacity of their components, restricting the maximum material thickness that can be pierced, which necessitates higher current loads and potentially leads to component failure.

Innovation Solution

A plasma cutting system that temporarily uses a higher pierce current than the steady-state current rating for a brief duration to pierce thicker materials, then drops to the standard current for cutting, preventing component overheating and extending the cutting capability beyond traditional limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a higher current load is used to pierce thicker materials, then the cutting capability is improved, but the torch components become susceptible to failure due to excessive heat

Engineering Contradiction:
Improvecutting capabilityVSAvoidcomponent reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system applies periodic action by using high current only during the brief piercing phase, then transitioning to a lower sustained current during the cutting phase. This temporal separation allows the system to achieve both thick material penetration and component protection.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary action by pre-heating and pre-piercing the material with high current before the main cutting operation. This preliminary high-current phase creates the initial penetration needed for subsequent cutting at lower, safer current levels.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If the maximum amperage rating is used for piercing, then the piercing capability is improved, but the torch can only cut materials up to a limited thickness

Engineering Contradiction:
Improvepiercing capabilityVSAvoidmaximum cut thickness
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system applies dynamics by making the current level variable rather than static. The controller dynamically adjusts current between a high piercing current and a lower cutting current, allowing the torch to handle materials thicker than the maximum rating would suggest.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the current parameter over time during the operation. By transitioning from high current during piercing to lower current during cutting, the system expands the effective range of material thicknesses beyond the traditional maximum rating limitation.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If a higher current load is applied for a brief duration to pierce thicker materials, then the cutting thickness capability is improved, but the risk of component overheating increases

Engineering Contradiction:
Improvecutting thickness capabilityVSAvoidcomponent temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The system applies the 'rushing through' principle by applying high current for a brief, controlled duration just long enough to achieve piercing, then immediately reducing to lower current. This minimizes thermal exposure while achieving the necessary penetration.

Inventive Principle:
Principle #21Skipping (Rushing through)

Solution Approach 2:

The periodic application of high current during piercing followed by lower current during cutting creates a thermal cycle that allows component cooling between high-heat events, managing overall temperature while maintaining cutting capability.

Inventive Principle:
Principle #19Periodic 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

Enables cutting of materials up to 25% thicker than previously possible without damaging the torch components, allowing for more versatile and efficient cutting operations.

Implementation Method 1

a plasma gas jet is emitted into the ambient atmosphere at a high temperature

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

plasma arc cutting torches

Methodology Applied
Scientific EffectPlasma: Plasma

Implementation Method 3

high current loads and temperatures associated with the ionized plasma jet

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Data Source

PatentEP3367762B1Enhanced plasma cutting system and method of operating the same
Publication Date: 2020.11.25 LINCOLN GLOBAL INC
  • EP3367762B1 patent drawingFigure 1
  • EP3367762B1 patent drawingFigure 2A~2F
  • EP3367762B1 patent drawingFigure 3~4

AI summary

Embodiments of the present invention include a plasma cutting system (100) having a plasma cutting power supply (10). The plasma cutting power supply (10) outputs a pierce current which is higher than a maximum operational current rating for a torch for the cutting operation for a determined duration. After the expiration of the duration the output current is reduced to a cutting current level. Embodiments allow for the cutting of thicker materials than known systems.