Gas Metal Arc Welding Control for Thin-Plate Bead Shape
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Solution Overview
Problem
Existing gas metal arc welding methods for thin plates face challenges in achieving optimal penetration and bead shape, particularly at high travel speeds, with CO2 welding producing convex beads and MAG welding having low heat input and porosity defects, while current techniques do not adequately address these issues.
Innovation Solution
A method for controlling gas metal arc welding using a shielding gas with 30% or more CO2, involving periodic switching of welding current and wire feeding between forward and backward periods, with controlled short-circuit time ratios to ensure optimal penetration and bead shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If CO2 welding is used for high-speed welding of thin plates, then welding speed and penetration stability are improved, but bead shape becomes convex and spatter increases
Solution Approach 1:
The patent applies periodic action by implementing pulsed current welding where the welding current is periodically switched on and off. This creates alternating heat input periods and non-heat input periods, allowing the molten pool to cool and solidify cyclically. The periodic cooling prevents excessive heat accumulation that causes convex bead formation, while maintaining high welding speeds through efficient heat utilization during active periods.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting welding current parameters (amplitude, pulse width, frequency) based on real-time welding conditions. By modifying current parameters periodically, the system optimizes heat input control to produce flat bead shapes while maintaining high welding speeds and stable penetration characteristics.
2Shape
If MAG welding is used to reduce spatter and penetration, then bead appearance improves, but welding speed decreases and porosity defects increase
Solution Approach 1:
The patent employs composite materials by using a mixed shielding gas composition (e.g., CO2 + Ar or CO2 + He) that combines the advantages of different gases. The mixture provides both the spatter reduction and good bead appearance characteristics of MAG welding while maintaining the high welding speed and penetration stability associated with CO2 welding, thus resolving the productivity loss.
Solution Approach 2:
The pulsed current mechanism creates periodic heat input that prevents excessive molten pool expansion, maintaining good bead appearance. Simultaneously, the periodic arcs ensure sufficient heat input for high welding speeds and deep penetration, avoiding the productivity reduction typical of conventional MAG welding.
3Object-generated harmful factors
If pulsed MAG welding is applied to reduce spatter, then spatter decreases, but penetration becomes insufficient and welding speed is limited
Solution Approach 1:
The patent applies parameter changes by optimizing pulsed current parameters including higher peak current amplitude and adjusted pulse duty cycle. These parameter modifications increase the effective heat input during pulse periods, ensuring sufficient penetration depth while maintaining spatter reduction benefits through the periodic current interruption.
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 method achieves improved bead shape and penetration performance, enhancing welding quality and optimizing production systems for thin plates regardless of travel speed.
Implementation Method 1
a welding wire 100 that generates an arc 9 with a base metal 200
Implementation Method 2
the welding wire 100 serves as a consumable electrode and is melted by arc heat 9 together with a base metal 200 to form a molten pool
Data Source
AI summary
A method for controlling gas metal arc welding using a shielding gas containing 30% or more of CO2 and using a thin plate as a material to be welded, in which feeding and welding current control are performed by switching a welding current to at least a current non-reduction period or a current reduction period, includes: when there are cycles including an arc period and a short-circuit period within a predetermined time, a short-circuit time ratio determination step of determining a ratio of the short-circuit period to the predetermined time; and a welding condition determination step of setting or correcting a welding condition so that the ratio of the short-circuit period determined in the short-circuit time ratio determination step is at least equal to or less than a predetermined threshold value or a calculated threshold value, or equal to a predetermined target value or a calculated target value.