SAW Electrode Preheating for Consistent Arc Start and Bead Profile
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In submerged arc welding (SAW), the electrode undergoes resistive heating at extended stick-out distances, leading to inconsistent output and bead profiles due to changes in electrode resistivity as it heats up during the start of the weld.
Innovation Solution
A system and process are provided to resistively heat the electrode using the welding power source before starting to lay down a weld bead, bringing the consumable welding electrode up to a heated cherry red color. This is achieved by advancing the electrode until it touches the workpiece, then providing a preheating current level until the electrode reaches a steady state temperature, before increasing the current to a welding level to establish an arc.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding starts when the electrode is cold, then the welding process can begin immediately, but the electrode resistivity changes during heating leading to inconsistent weld output and bead profile
Solution Approach 1:
The system applies preliminary heating action to the electrode before welding begins. A preheat current is applied to raise the electrode temperature to a predetermined level (e.g., cherry red color) before the welding arc is initiated, ensuring consistent resistivity and weld quality from the start
Solution Approach 2:
The system changes the temperature parameter of the electrode from cold to heated state before welding. By controlling the electrode temperature through preheating, the resistivity parameter is stabilized, which in turn stabilizes the weld output and bead profile
2Manufacturing precision
If the electrode is preheated to steady state temperature before welding, then weld consistency is improved, but additional time and current are required for the preheating process
Solution Approach 1:
The system applies partial preheating rather than full steady-state heating. The electrode is heated to a sufficient temperature (e.g., cherry red) that provides adequate weld consistency without requiring complete thermal equilibrium, thus reducing preheating time while maintaining quality
Solution Approach 2:
The preheating current is applied in a controlled periodic manner, allowing the electrode to heat to the required temperature quickly before transitioning to the welding phase, optimizing the balance between preheat duration and weld quality
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
The preheating process improves the consistency of the weld by stabilizing the electrode's temperature before welding, resulting in a more consistent output and bead profile.
Implementation Method 1
the electrode undergoes a significant amount of resistive heating
Implementation Method 2
increasing the preheating current level to a welding current level over an arc establishment period of time to establish an arc between the tip of the consumable welding electrode and the workpiece
Data Source
AI summary
A system and method for submerged arc welding. The system advances a consumable welding electrode toward a workpiece, and then stops the advancement when the consumable electrode makes contact with the workpiece. The system provides a preheating current level through the consumable welding electrode proximate the workpiece while the consumable welding electrode is in contact with the workpiece during a preheating period of time to preheat the portion of the consumable welding electrode without establishing an arc. The system then retracts the consumable welding electrode from the workpiece and increases the preheating current level to a welding current level over an arc establishment period of time to establish an arc between the consumable welding electrode and the workpiece. The system then begins to form a weld by advancing the consumable welding electrode toward the workpiece again, resulting in melting the consumable welding electrode and depositing molten metal onto the workpiece.