Multi-Pass Butt Weld Lamination Pattern to Minimize Bead Sagging
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Solution Overview
Problem
Existing welding methods for horizontal orientation, particularly in multi-pass welding, face challenges with bead sagging due to gravity, leading to defective external appearances and increased cycle times, especially when using portable welding robots without torch-angle changing mechanisms.
Innovation Solution
A multi-pass welding method that forms weld metal with a specific lamination pattern, including a boundary layer positioned closer to the front surface on the upper plate than the lower plate, and a lamination pattern calculation method to minimize bead sagging and achieve a favorable weld metal surface, using a database for groove shape and positional information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-pass welding is performed in horizontal orientation using conventional methods, then welding can be completed, but bead sagging occurs due to gravity leading to defective external appearance
Solution Approach 1:
The invention applies preliminary action by pre-forming a ground layer with specific geometric characteristics (wider at rear surface than at front surface) before depositing the finishing layer. This preliminary structure prevents bead sagging during subsequent welding passes by creating a supportive base that counteracts gravitational effects on molten metal.
Solution Approach 2:
The weld metal is segmented into multiple layers with distinct functions: a ground layer (first plurality of layers) that provides structural support and prevents sagging, and a finishing layer (second plurality of layers) that provides the final surface quality. This segmentation allows each layer to be optimized for its specific purpose.
2Manufacturing precision
If grinding processes are performed to adjust bead shape after bead sagging occurs, then external appearance can be improved, but cycle time increases significantly
Solution Approach 1:
The invention performs the shaping action preliminarily during the welding process itself by controlling the geometry of the ground layer, rather than performing corrective grinding after welding. The ground layer is formed with predetermined characteristics that prevent sagging, eliminating the need for post-weld grinding and reducing cycle time.
3Manufacturing precision
If front backing members are installed to prevent bead sagging at finishing layers, then weld quality can be maintained, but work efficiency decreases
Solution Approach 1:
The invention extracts and eliminates the need for front backing members by incorporating the sagging prevention function directly into the ground layer structure. The ground layer's geometric configuration (wider at rear than front) provides inherent support that replaces the function of external backing members, simplifying the overall welding process.
4Device complexity
If portable welding robots without torch-angle changing mechanisms are used, then equipment simplicity and portability are maintained, but horizontal-orientation welding difficulty increases
Solution Approach 1:
The invention makes the welding process self-service by using the ground layer structure itself to prevent bead sagging, eliminating the need for complex torch-angle adjustment mechanisms. The ground layer's geometry automatically provides the necessary support against gravity, allowing simple portable robots to perform horizontal welding effectively.
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 effectively minimizes bead sagging and ensures a favorable weld metal surface during multi-pass welding in horizontal orientation, even without torch-angle adjustments, by strategically forming the boundary layer and adjusting the lamination pattern based on positional information and groove characteristics.
Implementation Method 1
bead sagging tends to occur due to the effect of gravity
Data Source
AI summary
A multi-pass welding method is provided for minimizing bead sagging and forming a welded joint having a good weld metal surface, even during multi-pass welding in a horizontal orientation, and a multi-pass butt welded joint and a lamination pattern calculation method for a multi-pass weld formed by the method. The weld metal has a plurality of layers from the rear surface of a base material to the front surface thereof. The plurality of layers include a finishing layer having at least two layers including an end layer; and a ground layer for forming the finishing layer. A boundary layer, which is the layer of the ground layer adjacent to the finishing layer, is formed such that the position of an upper plate-side weld is closer to the front surface of the base material than the position of a lower plate-side weld.