Tandem Arc Welding Electrode Position Control

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Solution Overview

Problem

Existing tandem arc welding techniques fail to correctly align both leading and trailing electrodes with the weld line, especially when the weld line is tilted or the workpiece position differs from the previously taught position, leading to potential welding defects.

Innovation Solution

An electrode position control method that detects voltage changes on the electrodes to sense the workpiece's position, calculates correction amounts for each electrode's displacement, and adjusts their positions accordingly to align with the weld line, including a rotation center correction to maintain accurate alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a reference jig is used to detect electrode bending at a predetermined position, then the electrode positions can be corrected, but the method lacks flexibility and cannot handle tilted weld lines

Engineering Contradiction:
Improveelectrode position detection accuracyVSAvoidadaptability to tilted weld lines
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical reference jig system with an electrical sensing system. Voltage detectors measure voltage changes on the electrodes when they contact the workpiece, and a sensor processes this electrical information to detect workpiece position and calculate correction amounts. This substitution enables flexible adaptation to various workpiece positions and tilted weld lines while maintaining precise measurement capability.

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

2Reliability

If the weld line position differs from the taught position due to assembly errors, then welding defects may occur, but no technique exists to correct both electrode positions simultaneously

Engineering Contradiction:
Improvewelding qualityVSAvoidposition correction system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system employs self-service by using the electrodes themselves as sensing elements. The electrodes detect workpiece position through voltage changes when they contact the workpiece, and the sensor processes this information to calculate correction amounts for both electrodes. This self-sensing approach eliminates the need for separate sensing devices while ensuring both electrodes are corrected to maintain welding quality.

Inventive Principle:
Principle #25Self-service

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 method ensures accurate alignment of both electrodes with the weld line, preventing welding defects by dynamically correcting their positions based on real-time sensing and voltage changes, even when the workpiece position differs from the taught position.

Implementation Method 1

a voltage detecting step of detecting voltages on the leading electrode and the trailing electrode that are brought into contact with a welding workpiece to be welded

Methodology Applied
Scientific EffectElectrical contact sensing: Conduction (electrical)

Implementation Method 2

a sensing step of detecting positional information of the welding workpiece from electrical changes in the voltages on the leading electrode and the trailing electrode detected in the voltage detecting step

Methodology Applied
Scientific EffectElectrical change sensing: Electrical Resistance

Data Source

PatentEP2390040B1Electrode position control method for tandem ARC welding, robot controller for tandem ARC welding system, and tandem ARC welding system
Publication Date: 2019.08.28 KOBE STEEL LTD
  • EP2390040B1 patent drawingFigure 1
  • EP2390040B1 patent drawingFigure 2
  • EP2390040B1 patent drawingFigure 3A~3E

AI summary

An electrode position control method according to the present invention includes a voltage detecting step of detecting voltages on a leading electrode (2a) and a trailing electrode (2b) that are brought into contact with a welding workpiece (W), a sensing step of detecting positional information of the welding workpiece from electrical changes in the voltages, a correction amount calculating step of calculating a correction amount for correcting for positional displacement of each of the leading electrode and the trailing electrode with respect to a weld line from the positional information, and a position correcting step of correcting the respective positions of the electrodes by adding or subtracting the correction amount.