GMAW Weaving Width Control for 9% Ni LNG Tank Welding
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Solution Overview
Problem
Automatic welding of large-capacity LNG tanks is challenging due to the difference in physical properties between the steel sheet and the Ni-based alloy welding material, leading to issues like sagging, poor bead appearance, and incomplete fusion, especially when using GMAW methods with welding wires containing 5% or more Ni.
Innovation Solution
A control method and device for GMAW that sets work information including plate thickness, groove depth, and welding wire diameter, and adjusts weaving width based on pre-calculated layer height to optimize welding conditions, ensuring excellent welding quality by correcting welding conditions in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automatic welding by GMAW is used to improve welding work efficiency, then deposition efficiency is improved, but welding quality deteriorates due to inability to adjust welding conditions
Solution Approach 1:
The patent implements dynamic adjustment of welding parameters including weaving width, welding speed, and torch angle during the welding process. The control device automatically modifies these parameters based on real-time welding conditions, enabling the automatic welding system to adaptively respond to variations in the welding process while maintaining both high deposition efficiency and excellent welding quality.
2Manufacturing precision
If welding speed is reduced to ensure high quality welding, then welding quality is improved, but welding work efficiency decreases
Solution Approach 1:
The patent employs periodic weaving motion of the welding torch during the welding process. This periodic lateral movement of the torch creates a weaving pattern that distributes heat and molten metal more uniformly, preventing sagging and improving bead appearance while maintaining adequate welding speed. The weaving width and frequency are optimized to balance quality and efficiency.
3Stability of the object's composition
If welding wire with 5% or more Ni is used to match base material composition, then material compatibility is improved, but melting point difference causes sagging and incomplete fusion
Solution Approach 1:
The patent changes multiple welding parameters including torch angle, welding speed, and weaving width to compensate for the melting point difference between the Ni-based welding wire and the steel base material. By optimizing these parameters, the system achieves proper fusion and prevents sagging despite the 100°C or more melting point difference, ensuring both material compatibility and welding 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 solution enables high deposition efficiency and excellent welding quality in GMAW for LNG tanks, even with welding wires containing 5% or more Ni, by accurately adjusting weaving width and torch angle, thereby improving welding efficiency and quality.
Implementation Method 1
automatic welding by GMAW (Gas metal arc welding)
Implementation Method 2
the melting point of Ni-based alloy serving as a welding material is lower than the melting point of 9% Ni steel
Data Source
AI summary
A method for controlling a welding robot or a control device relating to GMAW when a groove is provided in a material being welded, the compositions of the material being welded and a welding wire are different from one another, and the welding wire contains 5% or more of Ni, the method having: setting execution information that includes at least one from among the plate thickness, the groove depth, and the estimated welding metal height, as well as at least one from among the gap size and the groove width in a central position at a layer height calculated in advance; and calculating a weaving width before or during welding on the basis of the execution information and setting or correcting welding conditions including at least the weaving width.