Arc Welding Head Optical Detection for Reliable Arc State Sensing

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Solution Overview

Problem

Conventional arc welding processes face challenges in accurately detecting the state of an electric arc due to interference from high currents and multiple welding devices, leading to false short-circuit detection, especially in robotic or automated systems.

Innovation Solution

A joining device that utilizes a light-receiving element to detect the electromagnetic radiation emitted by the arc, generating a light intensity signal for precise arc state determination, separate from conventional electrical parameter measurements, with an evaluation unit to control the welding process based on this signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional voltage measurements are used for arc detection, then the detection system is simple to implement, but the detection accuracy deteriorates due to interference from high currents and multiple welding devices

Engineering Contradiction:
Improvearc detection accuracyVSAvoidelectrical interference
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the electrical measurement system (voltage/current sensors) with an optical detection system (light receiving element). The light receiving element detects electromagnetic radiation from the arc, converting it to electrical signals that are processed to determine arc state. This substitution eliminates susceptibility to electrical interference from multiple welding devices while maintaining arc detection functionality.

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

Solution Approach 2:

The patent introduces electromagnetic radiation (light) as an intermediary medium between the arc and the detection system. Instead of directly measuring electrical parameters that are susceptible to interference, the system detects light emitted by the arc, which serves as an indirect but interference-free indicator of arc state.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If additional voltage measuring leads are used to decouple voltage measurement, then the measurement accuracy improves, but the device complexity increases

Engineering Contradiction:
Improvevoltage measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex electrical decoupling approach (additional measuring leads, isolation circuits) with a fundamentally different optical measurement approach. The light receiving element naturally provides electrical isolation since it detects optical signals rather than electrical signals, eliminating the need for complex decoupling circuitry while maintaining measurement accuracy.

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

3Device complexity

If voltage measuring lines are laid near welding lines, then the measurement system is compact, but the reliability deteriorates due to electrical interference

Engineering Contradiction:
Improvecable routing simplicityVSAvoiddetection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent substitutes electrical signal transmission with optical signal transmission. The light receiving element converts optical energy from the arc into electrical signals, which are then transmitted. This optical-to-electrical conversion at the source eliminates susceptibility to electromagnetic interference along the signal transmission path, maintaining reliability even with compact cable routing.

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

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

Enhances arc detection accuracy by isolating the light-receiving element from interference, allowing for precise control of welding parameters and reducing false detections, thus improving the reliability of automated welding processes.

Implementation Method 1

a light receiving element; and an evaluation device designed to receive a current light intensity signal, which includes light intensity information about a light intensity at the light receiving element

Methodology Applied
Scientific EffectElectromagnetic radiation detection: Photoelectric Effect

Data Source

PatentEP4647199A1Joining device and method for joining a workpiece
Publication Date: 2025.11.12 FRONIUS INT GMBH
  • EP4647199A1 patent drawingFigure 1~2
  • EP4647199A1 patent drawingFigure 3~4
  • EP4647199A1 patent drawingFigure 5~6

AI summary

The invention provides a method for joining a workpiece and a joining device. The joining device (100-700) comprises: a joining head (110; 310-710) configured to generate an electric arc (2) and thereby transfer energy to the workpiece (9) for joining; a light-receiving element (121-721); and an evaluation device (130; 230) configured to receive a current light intensity signal, which includes information about the light intensity at the light-receiving element (121-721), and which is also configured to determine, based on the light intensity signal, whether an electric arc (2) is currently burning.