Welding Electrode Preheating for Consistent Submerged Arc Starts
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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 through the electrode during a preheating period, followed by 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 patent applies preliminary action by preheating the electrode to a cherry red color (approximately 500-800°C) using resistive heating from the welding power source before initiating the weld bead deposition. This preheating step ensures the electrode reaches a stable temperature state, eliminating resistivity changes during welding and achieving consistent weld output and bead profile from the start of the welding process
2Manufacturing precision
If the electrode is preheated to cherry red color before welding, then weld consistency is improved, but additional time and energy are required for the preheating process
Solution Approach 1:
The patent merges the preheating function with the existing welding power source by utilizing its output to provide resistive heating to the electrode through the wire feed system. This integration eliminates the need for separate preheating equipment and allows the preheating current to be drawn from the same power source that will be used for welding, thereby reducing overall system complexity and energy waste
Solution Approach 2:
The electrode serves itself by using its own electrical conductivity to generate heat through resistive heating from the welding power source. The wire electrode acts as a heating element, converting electrical energy directly into thermal energy within the electrode material itself, achieving preheating without external heating devices
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 maintaining stable electrode temperature, resulting in a more consistent output and bead profile throughout the welding process.
Implementation Method 1
the electrode undergoes a significant amount of resistive heating
Implementation Method 2
an arc is struck as the current is brought up to a welding current level for welding
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.