ERW Steel Pipe Welding Monitoring for Cold Weld Detection
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Solution Overview
Problem
Existing methods struggle to accurately determine the boundary between the type 1 area where melt-welding is possible and the cold welding limit in electric resistance welded steel pipes, particularly in small-diameter pipes used for automobiles and structures, leading to defects such as dents and sputters due to insufficient heat input control.
Innovation Solution
A method and device for monitoring welding that involves imaging and processing the V-convergence point and molten steel discharge in electric resistance welded steel pipes to detect cold welding by measuring the distance or width of molten steel, using threshold values to determine whether cold welding has occurred, and controlling heat input within specific limits to prevent cold welding and welding slits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If heat input is reduced to avoid sputter generation, then surface quality improves, but cold welding occurs due to insufficient melting
Solution Approach 1:
The patent replaces conventional optical detection methods with X-ray imaging technology to detect the two-stage convergence phenomenon. This substitution enables more precise measurement of steel edge convergence and molten pool formation, allowing for accurate determination of the boundary between type 1 and type 2 areas, thereby preventing both sputter and cold welding through precise heat input control
Solution Approach 2:
The patent changes the detection parameter from optical imaging to X-ray imaging, which provides different penetration and contrast characteristics. This parameter change enables visualization of the internal molten pool structure and steel edge convergence that is not visible with optical methods, allowing for more accurate heat input control to prevent both sputter and cold welding
2Reliability
If heat input is increased to ensure full-thickness melting, then welding reliability improves, but welding slits and dents occur due to excessive heat input
Solution Approach 1:
The patent implements a feedback control system that uses X-ray imaging to detect the two-stage convergence phenomenon and molten pool formation in real-time during welding. The detected information is fed back to adjust heat input parameters, ensuring the welding process remains within the optimal type 1 area, thereby preventing both cold welding and excessive heat input defects
Solution Approach 2:
The patent replaces conventional optical detection with X-ray imaging to monitor the welding process. This substitution provides more accurate real-time feedback on steel edge convergence and molten pool formation, enabling precise control of heat input to prevent welding slits and dents while ensuring full-thickness melting
3Ease of operation
If conventional optical imaging is used to detect welding phenomena, then detection simplicity is maintained, but measurement precision is insufficient to accurately identify the type 1/type 2 boundary
Solution Approach 1:
The patent substitutes conventional optical imaging with X-ray imaging technology. This substitution overcomes the limitations of optical methods in detecting internal molten pool structure and steel edge convergence, providing superior measurement precision for identifying the type 1/type 2 boundary while maintaining automated detection capability
Solution Approach 2:
The patent changes the imaging modality parameter from optical to X-ray, which fundamentally improves the measurement precision of welding phenomena. X-ray imaging provides different interaction characteristics with the material, enabling accurate visualization of the two-stage convergence and molten pool formation that are critical for boundary detection
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
Enables accurate detection of cold welding in the type 1 area, preventing defects and ensuring robust welding without sputters or dents, thereby improving the quality of small-diameter electric resistance welded steel pipes.
Implementation Method 1
an image acquisition step in which, when an electric resistance welded steel pipe is welded, a V-convergence portion including an edge detection area and a V-convergence point, and a welding portion including a position where a molten steel starts to be discharged
Implementation Method 2
electric resistance welding phenomenon differs depending on an input power (heat input amount)
Implementation Method 3
electric resistance welding
Implementation Method 4
a welding portion including a position where a molten steel starts to be discharged from an inside of a wall thickness
Data Source
AI summary
A method for monitoring welding of an electric resistance welded steel pipe of the present invention includes: an image acquisition step in which, when an electric resistance welded steel pipe is welded, a V-convergence portion including an edge detection area and a V-convergence point, and a welding portion including a position where a molten steel starts to be discharged from an inside of a wall thickness and a bead, are imaged to obtain a captured image; a determination information acquisition step in which the captured image is image-processed, and a molten length from the V-convergence point to the position where the molten steel starts to be discharged or a molten width of the welding portion or a combination thereof is acquired as a determination information; and a determining step in which it is determined whether a cold welding has occurred by comparing the determination information with a determination threshold value set in advance for each wall thickness of the electric resistance welded steel pipe.