Plasma Arc Torch Nozzle Venting With Water Shield Cutting

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Solution Overview

Problem

Traditional plasma arc torches are costly due to expensive plasma gases and have limited cut speeds, primarily due to the use of expensive gases like H35 and F5, and are hindered by cut quality considerations.

Innovation Solution

A plasma arc torch system utilizing a vented nozzle with a liquid shield fluid, such as water, which reduces operational costs and enhances cut quality by using inexpensive gases like N2 and water as cutting mediums, combined with an efficient shield fluid delivery system to promote higher cut speeds and better edge appearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If expensive plasma gases (H35, F5) are used, then cut quality is improved, but operational cost increases

Engineering Contradiction:
Improvecut qualityVSAvoidoperational cost
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent replaces expensive plasma gases (H35, F5) with cheaper alternatives (air, nitrogen, oxygen) that can be readily obtained from atmospheric sources or standard gas supplies. This substitution maintains acceptable cut quality while dramatically reducing operational costs by using abundant, inexpensive materials instead of costly specialized gases.

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

Solution Approach 2:

The patent modifies the plasma generation parameters by changing the gas composition and introducing water injection. By adjusting the plasma gas type (from H35/F5 to air/nitrogen/oxygen) and controlling water injection rate and timing, the system achieves cost reduction while maintaining cut quality through parameter optimization rather than relying on expensive gases alone.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If traditional plasma gases are used, then cut quality is maintained, but cut speed is limited

Engineering Contradiction:
Improvecut qualityVSAvoidcut speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent introduces water injection into the plasma arc system, utilizing hydraulic principles to deliver liquid water through injection nozzles into the high-temperature plasma stream. The water rapidly vaporizes and expands, creating a high-velocity steam jet that enhances plasma arc penetration and increases cut speed while maintaining quality through controlled fluid dynamics.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent exploits the phase transition of water from liquid to vapor when injected into the plasma arc. The rapid vaporization process absorbs heat, controls the plasma temperature profile, and generates high-velocity expanding gases that enhance cutting performance and increase cut speed while preserving cut quality.

Inventive Principle:
Principle #36Phase transitions

3Manufacturing precision

If water injection is implemented, then cost is reduced and cut quality is improved, but system complexity increases

Engineering Contradiction:
Improvecut qualityVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the water delivery system into separate functional components: water storage tank, pump mechanism, injection nozzles positioned at specific locations, and control system. This segmentation allows each component to be optimized independently and simplifies maintenance while achieving the desired cost reduction and quality improvement through coordinated operation of modular elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses water as an intermediary substance that mediates between the plasma arc and the workpiece. The water injection serves multiple functions simultaneously: cooling the plasma arc, generating steam for enhanced cutting, controlling heat input, and improving cut quality. This intermediary approach achieves multiple benefits while keeping the system relatively simple by using water, a readily available and easily controlled substance.

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 system achieves significant cost reduction and improved cut quality with increased cutting speeds, utilizing inexpensive gases and water as a shield fluid, resulting in smoother cuts and reduced heat-affected zones.

Implementation Method 1

a water flow is provided to shield the plasma

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

the torch produces a plasma arc, which is a constricted jet of mostly ionized gas with high temperature

Methodology Applied
Scientific EffectPlasma: Plasma

Implementation Method 3

utilizing inexpensive gases and water as a shield fluid, resulting in smoother cuts and reduced heat-affected zones

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3231259B1Water injection and venting of a plasma arc torch
Publication Date: 2022.02.02 HYPERTHERM INC
  • EP3231259B1 patent drawingFigure 1
  • EP3231259B1 patent drawingFigure 2
  • EP3231259B1 patent drawingFigure 3

AI summary

A plasma arc torch system comprising a plasma arc torch is provided. The torch includes an electrode, a nozzle, a vent passage and a shield. The nozzle is spaced from the electrode to define a plasma chamber therebetween. The plasma chamber is configured to receive a plasma gas. The vent passage, disposed in the nozzle body, is configured to divert a portion of the plasma gas exiting the plasma chamber from a nozzle exit orifice. The shield is spaced from the nozzle to define a flow region therebetween. The flow region is configured to (i) receive a liquid and (ii) expel the liquid along with a plasma arc substantially surrounded by the liquid via a shield exit orifice.