Plasma Torch Secondary Media Switching With Parallel Feeds

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Solution Overview

Problem

Current plasma cutting technologies face challenges in quickly switching secondary media, such as gases or liquids, due to the limitations of existing valve arrangements, which hinder rapid adjustments during cutting processes, particularly when transitioning between different cutting operations or reacting to changes in the cutting process.

Innovation Solution

The plasma torch design incorporates at least two parallel feeds for secondary media within the housing, with individual valves for each feed, allowing for rapid switching and control of flow rates, pressures, and compositions of secondary media, including the ability to mix media within the plasma head, and features compact, electrically or pneumatically actuated valves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a common feed is used for secondary medium supply, then device complexity is reduced, but switching speed between different secondary media becomes too slow

Engineering Contradiction:
Improvefeed structureVSAvoidswitching speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The common feed is segmented into multiple separate feeds, each dedicated to a specific secondary medium. This allows independent control and rapid switching between different media (e.g., gas and liquid) without requiring flushing operations, directly resolving the contradiction between device simplicity and switching speed.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If valves are attached to the plasma torch shaft, then control precision is improved, but ease of operation in guide system becomes difficult

Engineering Contradiction:
Improvecontrol precisionVSAvoidease of operation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The valve assembly is extracted from the plasma torch shaft and mounted separately on the guide system. This allows precise control of secondary medium flow while maintaining ease of operation, as the valves can be accessed and adjusted independently without disrupting the torch shaft assembly or guide system mechanics.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If secondary medium switching is delayed, then device complexity is reduced, but productivity during transitions becomes too slow

Engineering Contradiction:
Improvevalve control systemVSAvoidcutting speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The system performs preliminary actions by pre-positioning multiple feeds with their respective secondary media ready for immediate activation. During transitions between cutting operations, the appropriate feed can be activated instantly without delay for medium changes, maintaining high productivity while keeping the control system relatively simple.

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

Enables rapid and precise control over secondary media flow, improving cut quality, reducing slag deposits, and enhancing cutting performance during transitions and complex cuts by allowing immediate adjustments to cutting parameters.

Implementation Method 1

The arc, constricted by a nozzle, is then called a plasma jet. The parameters of the plasma jet can be significantly influenced by the design of the nozzle and electrode.

Methodology Applied
Scientific EffectElectric arc: Electric Arc

Implementation Method 2

Plasma is a highly heated, electrically conductive gas consisting of positive and negative ions, electrons, and excited and neutral atoms and molecules. These gases ionize and dissociate due to the energy of an electric arc.

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 3

The arc, constricted by a nozzle, is then called a plasma jet. The parameters of the plasma jet can be significantly influenced by the design of the nozzle and electrode. These parameters include, for example, the jet diameter, temperature, energy density, and gas flow velocity.

Methodology Applied
Scientific EffectDe Laval nozzle effect: De Laval Nozzle

Data Source

PatentEP3491896B1Plasma torch
Publication Date: 2025.11.19 KJELLBERG STIFTUNG
  • EP3491896B1 patent drawingFigure 1
  • EP3491896B1 patent drawingFigure 2
  • EP3491896B1 patent drawingFigure 3

AI summary

The invention relates to a plasma torch, in particular a plasma cutting torch, wherein at least one feeder is used for conducting a secondary medium through a plasma torch housing to an opening in a protective nozzle cap and/or additional openings in a protective nozzle cap. Directly inside the plasma torch housing, at least one valve for opening and closing the feeder is provided in the at least one feeder.