Welding Wire Surface Scanning After Slag Removal

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Solution Overview

Problem

Existing scanning methods for metallic workpieces using a welding torch with a consumable welding wire often fail to reliably detect contact due to an insulating slag layer, leading to interrupted or inaccurate scanning processes.

Innovation Solution

A slag removal process is implemented before scanning, where the welding current is minimized, and the welding wire is moved rapidly forward and backward to remove slag, with the process repeating until multiple consecutive short circuits are detected, ensuring reliable contact detection and terminating when slag is likely removed, and additional conditions like wire feed speed and force thresholds are used to confirm slag removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the welding wire is used to scan the surface by detecting short circuits, then the scanning function is achieved, but slag accumulation blocks the short circuit detection

Engineering Contradiction:
Improveshort circuit detection reliabilityVSAvoidslag insulation effect
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing a slag removal process before the scanning process. The welding wire is moved rapidly back and forth across the workpiece surface to remove slag accumulation from the wire end before scanning begins, ensuring that the wire is free of insulating material that would prevent short circuit detection during scanning.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes operational parameters by reducing welding current to a minimum during the slag removal process, and controlling the wire feed speed to predominate in the forward direction. These parameter changes enable the wire to be moved rapidly across the surface to remove slag without causing welding, and the reduced current prevents arc ignition during slag removal.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the welding current is reduced to minimum during slag removal, then slag can be removed without arc ignition, but the scanning process cannot detect short circuits during slag removal

Engineering Contradiction:
Improveslag removal effectivenessVSAvoidshort circuit detection capability
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies periodic action by moving the welding wire cyclically forward and backward during the slag removal process. The wire is moved a predetermined distance toward the workpiece and then a shorter distance away, creating a rapid back-and-forth motion that repeatedly strikes the surface to remove slag. This periodic motion continues until a specified number of consecutive short circuits are detected, at which point the slag removal process is terminated.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent uses feedback by monitoring short circuit detection during the slag removal process. When a predetermined number of consecutive short circuits are detected, indicating that slag has been removed, the process automatically terminates. This feedback mechanism ensures that slag removal is complete before scanning begins, while allowing the system to know when to stop the slag removal process.

Inventive Principle:
Principle #23Feedback

3Productivity

If the welding wire is moved rapidly back and forth to remove slag, then slag removal speed increases, but the process time increases without proper termination criteria

Engineering Contradiction:
Improveslag removal speedVSAvoidslag removal process time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent applies the skipping principle by rapidly moving the welding wire through the slag removal process at high speed, then quickly transitioning to the scanning process once slag removal is complete. The predetermined number of consecutive short circuits criterion allows the system to rush through the slag removal phase efficiently without unnecessary delays, ensuring quick termination once the wire is clean.

Inventive Principle:
Principle #21Skipping (Rushing through)

4Reliability

If the wire feed speed is increased before slag removal, then slag removal effectiveness improves, but energy consumption increases

Engineering Contradiction:
Improveslag removal completenessVSAvoidwire feeder energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by increasing wire feed speed only during the specific slag removal phase when needed, rather than maintaining high speed continuously. The wire feed speed is increased before slag removal to ensure effective slag removal, then returned to normal scanning speed afterward, thus limiting energy consumption to only when necessary for slag removal effectiveness.

Inventive Principle:
Principle #16Partial or excessive 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

Ensures quick and error-free scanning by reliably removing slag, allowing for consistent short circuit detection and preventing false triggers, with a defined number of consecutive shorts and force measurements confirming successful slag removal.

Implementation Method 1

the welding wire is moved at a forward speed towards the surface of the workpiece until a welding power source detects contact of the welding wire with the workpiece

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

Slag or silicates can accumulate on the welding wire after a welding process (especially with steel alloys), acting as an insulator

Methodology Applied
Scientific EffectElectrical Insulation: Electrical Resistance

Data Source

PatentEP4061572B1Method for scanning the surface of metallic workpieces
Publication Date: 2023.07.12 FRONIUS INT GMBH
  • EP4061572B1 patent drawingFigure 1~2
  • EP4061572B1 patent drawingFigure 3
  • EP4061572B1 patent drawingFigure 4

AI summary

Method for scanning the surface (O) of metal workpieces (W), wherein, during a scanning process (AP), a welding torch (1) with a consumable welding wire (2) is moved over and towards the surface (O) of the workpiece (W), until contact of the welding wire (2) with the workpiece (W) is detected, and the welding wire (2) is subsequently moved away from the workpiece (W) again, wherein, before the scanning process (AP), a slag-removal process (SE) is carried out to remove slag at the end of the welding wire (2), wherein the welding current (I) is lowered to a minimum, and the welding wire (2) is moved cyclically with a rapid recurrent forward/backward movement over a prescribed length of travel in the direction of the workpiece (W), and by a smaller amount of travel away from the workpiece (W) again, until a short circuit between the welding wire (2) and the workpiece (W) is detected, whereupon the slag-removal process (SE) is ended, and, if no short circuit (KS) is detected, the slag-removal process (SE) is repeated, and, if a number of short circuits (KS) are detected one after the other, the slag-removal process (SE) is ended.