Structured-Light Weld Pool Control for Consistent Seam Penetration
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Solution Overview
Problem
Existing welding technologies face challenges in achieving uniform penetration of weld seams due to variations in groove clearance, heat dissipation, and joint mismatches, particularly in robot automatic welding, where traditional sensing methods are limited by accuracy and cost, and visual sensing technologies require complex modeling and large training data.
Innovation Solution
A control device and method utilizing frontal visual sensing with a structured light source and sensor to adjust welding current based on weld pool depression features, ensuring consistent penetration by processing structured light spot images and filtering out arc interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sensing methods (ultrasonic detection, infrared thermometry) are used to detect weld pool penetration state, then real-time detection capability is provided, but measurement precision is limited due to temperature difference influence on wave velocity and thermal emissivity fluctuations
Solution Approach 1:
The patent replaces traditional mechanical/acoustic sensing methods (ultrasonic detection) and thermal sensing methods (infrared thermometry) with an optical sensing system. The visual sensing unit captures images of the weld pool, and image processing algorithms extract penetration state information from these optical images, avoiding the limitations of wave velocity changes due to temperature and thermal emissivity fluctuations.
Solution Approach 2:
The patent changes the detection parameter from physical measurements (ultrasonic wave velocity, thermal emissivity) to optical parameter analysis. By analyzing the grayscale characteristics and geometric features of weld pool images, the system extracts penetration state information without being affected by temperature-induced parameter variations in traditional sensing methods.
2Loss of information
If visual sensing technology with artificial neural network modeling is used to establish mapping relation between weld pool image characteristics and penetration state, then rich information is obtained, but device complexity and modeling requirements increase significantly
Solution Approach 1:
The patent extracts only the essential geometric and grayscale characteristics from weld pool images that are directly related to penetration state, rather than using comprehensive neural network modeling of all image features. This extraction approach focuses on key parameters such as weld pool area, shape factors, and intensity distributions, simplifying the relationship between image characteristics and penetration state.
Solution Approach 2:
The patent transforms the complex neural network modeling problem into a parameter-based analysis by identifying specific geometric and optical parameters from weld pool images that correlate with penetration state. This parameter extraction method reduces modeling complexity while maintaining information richness.
3Productivity
If robot automatic welding with fixed welding specifications is used to improve welding efficiency and repeatability, then high efficiency and good repeatability are achieved, but adaptability to groove clearance changes and heat dissipation variations is lost
Solution Approach 1:
The patent implements a closed-loop feedback control system where the visual sensing unit continuously monitors weld pool characteristics during the welding process, the calculation control unit analyzes these characteristics to determine penetration state, and the welding current is adjusted in real-time based on this analysis. This feedback mechanism enables the system to adapt to groove clearance changes and heat dissipation variations while maintaining consistent penetration 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 achieves uniform and consistent weld penetration with a simple, cost-effective structure, suitable for filler-wire-free DC gas tungsten arc welding of tight butt joints, especially in aerospace manufacturing, by maintaining a constant weld pool depression feature.
Implementation Method 1
the structured light source is configured to emit single line structured light and irradiate the weld pool by the single line structured light
Implementation Method 2
collect structured light spot images formed by irradiating the single line structured light on surfaces of the weld pool and the welding workpiece
Data Source
AI summary
The present invention discloses a control device and method for formation of a weld seam based on frontal visual sensing of a weld pool. In the present disclosure, structural light is adopted to irradiate the concave surface of the weld pool, and a visual sensor is adopted to acquire corresponding structured light images. The weld pool depression feature is acquired through image processing. The welding current is adjusted in real time to maintain the weld pool depression feature constant, and thus the uniform backside width of the weld seam can be acquired to achieve uniform and consistent penetration of the weld seam. The present disclosure only relies on the structural light information on the topside of the weld pool to achieve the control of formation of the weld seam and can be applied to the filler-wire-free DC gas tungsten arc welding of tight butt joints.