Laser Welding Head Seam Tracking With Modeled Joint Detection
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Solution Overview
Problem
In laser welding processes, the unreliable detection of joining gap positions due to geometric variations and reflective properties of workpieces leads to measurement curves with many outliers, making it difficult to accurately position the welding laser and assess seam quality.
Innovation Solution
A method using high-contrast gray images captured with coaxial LED illumination and a camera, where measurement data is processed to fit a model of the joint course, reducing outliers and allowing for accurate determination of joining positions and quality characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If triangulation method with laser line is used to detect joining gap, then joining position can be identified, but detection reliability deteriorates when workpieces have different reflective properties or geometric variations
Solution Approach 1:
The patent introduces an intermediary mathematical model that acts as a mediator between the raw measurement data and the final joining position determination. This model filters out outliers caused by reflective property variations while preserving the true joining gap position, thus resolving the contradiction between measurement precision and detection reliability.
Solution Approach 2:
The patent changes the parameter representation from direct raw measurement values to modeled parameters that describe the expected geometric characteristics of the joining gap. By transforming the data through a mathematical model, the system achieves reliable detection despite variations in reflective properties and geometric tolerances.
2Measurement precision
If measurement is performed over entire length to account for component variations, then positioning accuracy improves, but measurement time and data processing complexity increase
Solution Approach 1:
The patent extracts only the essential geometric features needed for accurate positioning from the complete measurement data set. By identifying and removing outliers through mathematical modeling, the system achieves high positioning accuracy without requiring processing of all measurement points, thus reducing measurement time and computational complexity.
Solution Approach 2:
The patent performs preliminary filtering and modeling of measurement data to identify the true joining gap position before final positioning decisions are made. This preliminary action of removing outliers early in the process prevents unnecessary processing of erroneous data, saving time while maintaining accuracy.
3Loss of information
If gray scale image is used instead of triangulation line, then joining gap visualization improves, but outliers increase when joining gap closes or reflection properties change
Solution Approach 1:
The patent uses a mathematical model as an intermediary between the gray scale image data and the joining gap position determination. This model provides a consistent geometric framework that maintains detection reliability even when the visual appearance of the joining gap changes due to closure or reflection variations.
Solution Approach 2:
The patent transforms the visual information from gray scale images into standardized geometric parameters through mathematical modeling. This parameter transformation ensures that the joining gap position can be reliably determined regardless of changes in visual appearance caused by gap closure or reflection property variations.
4Productivity
If measurement data with outliers is used to control welding laser, then productivity improves, but manufacturing precision deteriorates due to incorrect positioning
Solution Approach 1:
The patent extracts and removes outlier data points from the measurement set before using the data to control the welding laser. By eliminating erroneous positions while retaining valid measurement data, the system maintains high welding speed without sacrificing positioning accuracy, thus resolving the contradiction between productivity and manufacturing precision.
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
This approach enables reliable detection of joining gap positions without outliers, improving the accuracy of seam tracking and quality assessment, and allows for precise control of the welding laser along the measured curve.
Implementation Method 1
an illumination device (19), the illumination beam path of which being coaxially coupled into the viewing beam path (17) and into the work laser beam path (10)
Data Source
AI summary
A method for identifying joining positions of workpieces includes capturing images of a joint by a camera, determining measurement data for the joining positions associated with a course of the joint from the images of the joint, determining a mathematical model of the joint course from a part of the measurement data, providing a curve based on the mathematical model for positioning a welding laser during a laser welding process along the curve.