Welding Wire Slag Removal via Cyclic Movement

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Solution Overview

Problem

Existing welding methods face challenges in reliably igniting the arc when slag adheres to the end of the welding wire, leading to potential wire buckling, deformation of the workpiece, and inefficiencies in slag removal processes.

Innovation Solution

The method involves reducing welding current to a minimum during slag removal, using rapid repetitive forward and backward movements of the welding wire to detach slag, and employing short-circuit monitoring to ensure safe arc ignition without interrupting the welding process, followed by SFI ignition to maintain process efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the welding wire is pressed against the workpiece surface to remove slag, then slag removal is achieved, but the welding wire is damaged

Engineering Contradiction:
Improvearc ignition reliabilityVSAvoidwelding wire integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent replaces mechanical pressing of the welding wire against the workpiece with an automated slag removal system that uses controlled wire movement and current reduction. The control unit automatically detects slag presence and initiates the removal process by reducing current and moving the wire back and forth, eliminating the need for manual pressing that damages the wire.

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

Solution Approach 2:

The system enables self-service by allowing the welding wire to remove its own slag automatically through controlled movement and current adjustment. The wire is moved back and forth across the workpiece surface under automated control, and when slag is detected, the system automatically initiates removal without external intervention, preventing wire damage while maintaining reliability.

Inventive Principle:
Principle #25Self-service

2Reliability

If the entire robotic arm is moved to remove slag by rubbing the welding wire on the workpiece, then slag is removed, but the device complexity increases

Engineering Contradiction:
Improveslag removal effectivenessVSAvoidrobotic arm movement requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the slag removal function from the complex robotic arm movement system and implements it as a separate, simplified automated process. The control unit independently manages slag removal by controlling wire feed movement and current adjustment, separating this function from the main robotic positioning system and reducing overall device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The welding wire serves multiple functions: it performs both welding and automated slag removal. The same wire that deposits material also removes slag through controlled back-and-forth movement when slag is detected, eliminating the need for separate slag removal mechanisms and reducing device complexity.

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

3Productivity

If the welding wire is moved rapidly back and forth for slag removal, then slag removal efficiency increases, but the risk of wire buckling increases

Engineering Contradiction:
Improveslag removal speedVSAvoidwelding wire stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent implements periodic action by moving the welding wire back and forth at controlled intervals during slag removal. The wire is advanced toward the workpiece, reversed, and pulled back in a rhythmic cycle, allowing efficient slag removal while maintaining wire stability through controlled, repetitive motion rather than continuous rapid movement.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts wire movement based on real-time conditions. When slag is detected, the wire movement is activated; when slag is removed, movement stops. The movement speed and amplitude are dynamically controlled to prevent wire buckling while maintaining removal efficiency, adapting to the actual slag condition.

Inventive Principle:
Principle #15Dynamics

4Productivity

If slag remains on the welding wire end, then the welding process can continue without interruption, but arc ignition becomes unreliable

Engineering Contradiction:
Improvewelding process continuityVSAvoidarc ignition reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary action by detecting slag on the welding wire end before it prevents arc ignition. The control unit continuously monitors wire position and detects slag presence in advance, initiating automated removal before the welding process is affected, ensuring both continuity and reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring welding parameters and wire position to detect slag presence. When slag is detected, the system automatically adjusts wire movement and current to remove the slag, then resumes normal welding. This closed-loop feedback ensures reliable arc ignition while maintaining process continuity.

Inventive Principle:
Principle #23Feedback

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 effectively removes slag without delaying arc ignition, preventing wire buckling and workpiece deformation, and ensures reliable, efficient welding by automating slag removal and optimizing arc ignition.

Implementation Method 1

the welding wire with a fast repetitive forward / backward movement cyclically a predetermined path length in direction Workpiece and is moved away from the workpiece again by a smaller distance, so that the promotion of the welding wire to the workpiece predominates until a short circuit monitor detects a short circuit

Methodology Applied
Scientific EffectImpact force: Impact Force

Implementation Method 2

during a welding process, during which an arc burns between the welding wire and the workpiece

Methodology Applied
Scientific EffectElectric arc: Electric Arc

Implementation Method 3

an arc burns between the welding wire and the workpiece

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2007542B1Method of welding a workpiece
Publication Date: 2010.04.28 FRONIUS INT GMBH
  • EP2007542B1 patent drawingFigure 1
  • EP2007542B1 patent drawingFigure 2
  • EP2007542B1 patent drawingFigure 3

AI summary

The invention describes a method of welding a workpiece (16) having a consumable welding wire (13) which is moved essentially in the direction of the workpiece (16) during a welding process by means of a wire feed unit (11), wherein a process for removing slag (42) at the end of the welding wire (13) is started and carried out. To provide a welding process which is not impaired by slag (42) possibly adhering to that end of the welding wire (13) which is to make contact and ensure reliable striking of the arc (15), provision is made for the welding current (I) to be reduced to a minimum at the start of the slag-removal process, and for the welding wire (13), during the slag-removal process, to be moved cyclically with a rapid recurring forward/backward movement by a predetermined displacement length in the direction of the workpiece (16) and by a smaller displacement distance away from the workpiece (16) again until a short circuit between the welding wire (13) and the workpiece (16) is detected by short-circuit monitoring, whereupon the slag-removal process is ended.