Arc Welding Current Control for Bead Shape Stability
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Solution Overview
Problem
Consumable electrode-type arc welding methods, such as pulse welding and short-circuit welding, face challenges in maintaining stable heat input and preventing defects like incomplete fusion and sputter, especially in position welding like vertical and overhead welding.
Innovation Solution
A method where pulse welding and short-circuit welding are alternately repeated, with the welding current controlled to be lower before shifting from pulse to short-circuit welding, and the current is managed to prevent sudden changes that cause sputter, ensuring stable heat input and bead shape control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pulse welding is used to reduce heat input, then heat input is reduced, but arc length must be long which prevents stable welding and reduces manufacturing precision
Solution Approach 1:
The patent applies periodic action by alternating between pulse welding and short-circuit welding in a cyclic manner. The pulse welding phase provides controlled heat input with reduced energy consumption, while the short-circuit welding phase ensures stable arc length and proper bead formation. This periodic switching resolves the contradiction by combining the advantages of both welding modes throughout the welding process.
Solution Approach 2:
The patent merges two different welding methods (pulse welding and short-circuit welding) into a single hybrid welding process. By combining the low heat input characteristic of pulse welding with the stable arc length characteristic of short-circuit welding, the invention achieves both reduced heat input and improved bead shape precision simultaneously.
2Length of moving object
If short-circuit welding is used to maintain short arc length, then arc length is short, but heat input is insufficient causing incomplete fusion and sputter
Solution Approach 1:
The patent uses periodic action to switch between short-circuit welding (maintaining short arc length) and pulse welding (providing sufficient heat input). During the short-circuit welding phase, the arc length remains short as required, while during the pulse welding phase, the heat input is increased to ensure complete fusion and prevent sputter, thus resolving the contradiction.
Solution Approach 2:
The patent applies preliminary action by performing pulse welding before short-circuit welding in each cycle. The pulse welding phase preliminarily provides sufficient heat input and melts the materials properly, preparing the conditions for the subsequent short-circuit welding phase where short arc length is maintained without causing incomplete fusion.
3Manufacturing precision
If pulse welding and short-circuit welding are alternately repeated, then bead shape is improved, but sputter occurs due to sudden current changes
Solution Approach 1:
The patent applies dynamics by making the welding current change gradually and continuously when transitioning between pulse welding and short-circuit welding modes, rather than abruptly. The current is increased or decreased step-by-step through multiple stages, which prevents sudden current changes that would cause sputter, while still maintaining the alternating welding pattern needed for good bead shape.
Solution Approach 2:
The patent uses beforehand cushioning by introducing intermediate current levels between the high current of pulse welding and the low current of short-circuit welding. These intermediate levels act as a cushion, preventing direct and sudden transitions between extreme current values, thereby avoiding sputter while maintaining the benefits of alternating welding modes.
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 prevents sputter and stabilizes the welding process, allowing for improved bead shape and successful position welding by controlling heat input and arc dynamics.
Implementation Method 1
consumable electrode-type arc welding
Data Source
AI summary
In a consumable electrode-type arc welding in which pulse welding and short-circuit welding are alternately repeated, a welding current is controlled such that a welding current immediately before shifting from the pulse welding to the short-circuit welding is lower than a base current in a pulse.