Oxy-Fuel Torch Flame Sensing for Ignition and Standoff Control

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Solution Overview

Problem

Current automated gas cutting torch systems face inconsistencies in operation due to the vulnerability of sensors to harsh environments and the need for additional electronics, leading to increased costs and reduced reliability, particularly in features like kindling temperature detection, automatic ignition, and standoff control.

Innovation Solution

An oxy-fuel thermal processing system that uses a current driver and voltage sensor to measure the electrical characteristics of the torch flame, allowing a microprocessor to calculate the slope of the current-voltage relationship and adjust the gas mixture based on predetermined ranges, thereby eliminating the need for physical sensors and minimizing hardware requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical sensors are mounted within the torch to detect kindling temperature, then detection capability is improved, but the system becomes vulnerable to abrasion and particulate deposition

Engineering Contradiction:
Improvekindling temperature detectionVSAvoidsensor durability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces optical sensors with electrical resistance measurement of the flame itself. Instead of using external optical components that are vulnerable to damage, the system measures the electrical properties of the flame directly, substituting a fragile optical detection system with a more robust electrical measurement approach that uses the flame as the sensing element.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The flame serves its dual purpose of both heating the workpiece and acting as the sensing element for temperature detection. By measuring the electrical resistance of the flame itself, the system eliminates the need for separate sensors, allowing the flame to 'sense' its own properties and provide feedback for control.

Inventive Principle:
Principle #25Self-service

2Extent of automation

If additional sensors and electronics are added to achieve automatic ignition and standoff control, then automation capability is improved, but system cost and complexity increase

Engineering Contradiction:
Improveautomatic ignition and standoff controlVSAvoidhardware requirements
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The patent makes the flame serve multiple functions simultaneously: it acts as both the heating source and the sensing element for temperature detection. This multi-functionality eliminates the need for separate sensors and reduces system complexity, as the same flame that performs the thermal processing also provides the feedback signal for automatic control.

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

Solution Approach 2:

The system monitors changes in electrical resistance of the flame as a parameter to detect kindling temperature and control the process. By using electrical resistance as the key parameter instead of optical properties, the system achieves automation with simpler hardware that doesn't require complex optical sensors or additional electronics.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If optical sensors are mounted on the exterior of the torch for standoff control, then measurement capability is improved, but the sensors are susceptible to damage from debris

Engineering Contradiction:
Improvestandoff distance measurementVSAvoiddebris damage
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces external optical sensors with internal electrical resistance measurement of the flame. Instead of mounting vulnerable optical components on the torch exterior, the system uses electrical probes that measure the flame's properties from within the torch assembly, eliminating exposure to debris and harsh external conditions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If the cutting oxygen bore diameter is reduced, then torch precision is improved, but optical sensor implementation becomes impossible

Engineering Contradiction:
Improvecutting precisionVSAvoidkindling temperature detection
Core Design Contradiction:
Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent substitutes optical sensors with electrical resistance measurement, allowing detection of kindling temperature through the small cutting oxygen bore. Electrical probes can be positioned within the restricted space to measure flame properties, whereas optical sensors physically cannot fit through the narrow bore diameter.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electrical resistance measurement acts as an intermediary that can be obtained through the constrained geometry of the torch. By measuring electrical properties rather than optical properties, the system finds a detection method that is compatible with the physical constraints of the torch design.

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

This approach provides reliable, economical, and robust automatic control of the cutting process by accurately determining kindling temperature, ensuring consistent ignition, and maintaining optimal standoff distance without the need for additional sensors or complex electronics, enhancing the system's reliability and reducing costs.

Implementation Method 1

a current driver coupled between the first and second surfaces for driving a current between the first and second surfaces, the first and second surfaces exposed to a flame of the torch

Methodology Applied
Scientific EffectElectrical conduction through plasma: Conduction (electrical)

Implementation Method 2

a voltage sensor coupled between the first and second surfaces for sensing a voltage response to a driven current supplied by the current driver

Methodology Applied
Scientific EffectElectrical resistance measurement: Electrical Resistance

Data Source

PatentEP2969345B1Process parameter detection using flame electrical characteristics in oxy-fuel thermal processing
Publication Date: 2021.10.20 ESAB GROUP INC
  • EP2969345B1 patent drawingFigure 1~2
  • EP2969345B1 patent drawingFigure 3~4A
  • EP2969345B1 patent drawingFigure 4B~5

AI summary

An automated oxy-fuel thermal processing system including an oxy-fuel torch, an automated machine tool operatively coupled to the torch for moving the torch relative to a work piece, and a circuit including a voltage source or a current electrically connected to the torch and configured to be electrically connected to the work piece. The automated oxy-fuel thermal processing system may further include a processor that is operatively connected to the torch, the automated machine tool, the circuit, and the voltage source or current source, wherein the processor is configured to control the operation of the torch, the automated machine tool and the voltage source or current source, and to monitor a current or voltage in the circuit in a predefined manner.