Pulse Welding Waveform with Non-Zero Acceleration Transitions
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Solution Overview
Problem
Existing pulsed MIG welding systems generate undesirable arc noise and experience difficulties with specialty wires like Inconel, Monel, Hastelloy, aluminum, and stainless steel due to sharp edges and rapid slope changes, leading to issues such as craters and arc outages.
Innovation Solution
A method of pulse welding that employs a waveform with gradual slope transitions, utilizing non-zero acceleration during transitions between peak and background portions, allowing for controlled soft pulsed MIG welding with current and voltage control, and generation using an inverter and microprocessor algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sharp edges and rapid slope changes are used in the waveform, then transition speed between peak and background is improved, but arc noise increases and weld quality deteriorates
Solution Approach 1:
The patent applies curvature by replacing sharp edges and rapid slope changes with gradual, curved transitions in the waveform. The waveform generator creates smooth transitions between peak and background portions using non-zero acceleration profiles, eliminating the abrupt angular changes that generate arc noise. This curvature principle directly resolves the contradiction by maintaining fast transition capability while removing the harmful sharp edges through mathematical smoothing of the waveform profile.
2Loss of time
If rapid slope changes from peak to background are used, then response time is improved, but arc outages occur at lower currents
Solution Approach 1:
The patent implements dynamics by using variable acceleration profiles during waveform transitions. Instead of fixed slope changes, the system dynamically adjusts the rate of change based on the current state, ensuring non-zero acceleration throughout the transition. This dynamic control allows the waveform to respond quickly to timing requirements while maintaining sufficient current levels to prevent arc outages, resolving the contradiction between response time and arc stability.
3Productivity
If fast slope changes from peak to background and back to peak are used, then cycle frequency is improved, but current over and under shoots occur
Solution Approach 1:
The patent employs feedback mechanisms through the waveform generator that continuously monitors and adjusts the current profile during transitions. By using non-zero acceleration control and comparing actual current levels against target profiles, the system can compensate for overshoot and undershoot conditions. This feedback control enables high cycle frequencies to be maintained while preventing current excursions that would compromise weld precision.
4Use of energy by moving object
If exponential decay during tail out is used, then energy control in surface tension transfer is improved, but arc noise is not sufficiently reduced
Solution Approach 1:
The patent applies parameter changes by modifying multiple waveform characteristics simultaneously rather than relying solely on exponential decay. The system changes the acceleration profile, transition duration, and slope characteristics to achieve both energy control and noise reduction. By adjusting these parameters to maintain non-zero acceleration throughout transitions, the patent achieves superior arc noise reduction while preserving effective energy delivery for surface tension transfer.
Data Source
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Figure 2
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AI summary
A method and system for pulse welding provides an output pulse waveform. The waveform has at least a frequency from a range of available frequencies not limited to harmonic frequencies. The waveform provides power suitable for welding, and has a plurality of background portions alternating with a plurality of peak portions. A transition down occurs from the peak portion to the background portion with a first acceleration and a transition up occurs from the background portion to the peak portion with a second acceleration. At least one of the first and second accelerations are non-zero over at least most of the transition. The waveform is preferably created by switching an inverter. Both accelerations may be non-zero, and each transition may have two accelerations, one negative closer to the peak, and one positive closer to the background. The accelerations may be constant with opposite polarity. Preferably the process is current controlled during the transitions. The process frequency may be fixed or varying.