Welding Torch Weaving Control for Accurate Through-Arc Seam Tracking
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Solution Overview
Problem
The accuracy of through arc seam tracking in robotic arc welding is compromised by the use of welding waveforms with pulse portions, due to frequent changes in welding current levels, which affect the precision of weld quality assessment.
Innovation Solution
A robotic electric arc welding system that includes a welding torch, a robot controller for controlling weaving movements, and a welding power supply that samples weld parameters to generate a weld quality score. The power supply adjusts the sampling period based on weave frequency or torch position information and records through arc seam tracking data to calculate corrections to the weld path from welding current data classified as corresponding to pulse or low current portions of the waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If welding waveforms with pulse portions are used to control welding current levels, then welding process control is improved, but through arc seam tracking accuracy deteriorates due to frequently changing current levels
Solution Approach 1:
The patent segments the welding waveform into distinct pulse portions and low current portions, and correspondingly segments the welding current data into classified portions. This segmentation allows the system to treat different waveform phases differently, sampling data only during low current portions where arc stability is higher, thereby maintaining seam tracking accuracy while still utilizing pulse waveform benefits for welding process control.
Solution Approach 2:
The patent applies local quality by selectively sampling welding current data only during specific portions of the waveform (low current portions) rather than uniformly across all portions. This localized sampling approach ensures that quality assessment is based on data from the most stable arc conditions, improving measurement precision without sacrificing the overall welding process control benefits of pulse waveforms.
2Adaptability or versatility
If welding current levels are frequently changed during pulse portions, then welding process adaptability is improved, but weld quality assessment precision deteriorates
Solution Approach 1:
The patent performs preliminary classification of welding current data into pulse current portions and low current portions before quality assessment. By pre-identifying and separating data from low current portions, the system ensures that quality metrics are calculated from stable, reliable data points, preventing the deterioration of assessment precision that would result from including noisy pulse portion data.
Solution Approach 2:
The patent dynamically adjusts the sampling strategy based on the instantaneous state of the welding waveform. The system continuously monitors waveform phase and adaptively selects which data points to sample and include in quality calculations, transitioning between different sampling modes depending on whether the system is in a pulse portion or low current portion, thereby maintaining precision despite frequent current changes.
3Device complexity
If fixed sampling period is used for quality assessment, then system simplicity is maintained, but accuracy of weld quality score deteriorates under varying weave frequencies
Solution Approach 1:
The patent implements a dynamic sampling period that automatically adjusts based on the detected weave frequency. When weave frequency increases, the sampling period decreases proportionally, ensuring that the sampling rate remains synchronized with the weaving motion. This dynamic adjustment maintains measurement precision across varying operating conditions without requiring complex manual configuration.
Solution Approach 2:
The patent incorporates feedback mechanisms where the system continuously monitors the actual weave frequency during welding and uses this information to adjust the sampling period in real-time. This closed-loop control ensures that the sampling system remains synchronized with the weaving torch motion, maintaining accuracy even as weave frequency changes, while keeping the adjustment process automatic and simple.
Data Source
AI summary
A robotic electric arc welding system includes a welding torch, a welding robot configured to manipulate the welding torch during a welding operation, a robot controller operatively connected to the welding robot to control weaving movements of the welding torch along a weld seam and at a weave frequency and weave period, and a welding power supply operatively connected to the welding torch to control a welding waveform, and operatively connected to the robot controller for communication therewith. The welding power supply is configured to sample a plurality of weld parameters during a sampling period of the welding operation and form an analysis packet, and process the analysis packet to generate a weld quality score, wherein the welding power supply obtains the weave frequency or the weave period and automatically adjusts the sampling period for forming the analysis packet based on the weave frequency or the weave period.