Double-Pulse Welding Waveform to Prevent Contact Tip Fusion
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Solution Overview
Problem
Welding processes using wire electrodes often experience issues with the wire fusing to the contact tip, leading to disruptions in the welding process due to spot welds or fusion events, which can result in hard shorts and inconsistent wire feed speeds.
Innovation Solution
Implementing a double pulse waveform with a peak phase and a background phase, where the first pulse is above a threshold current to transfer molten wire and the second pulse is below the threshold to dislodge any spot welds between the wire and the contact tip, minimizing energy addition and preventing further fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire electrode is used to establish an electrical arc during welding, then the welding process can be initiated and maintained, but the wire electrode may fuse to the contact tip causing disruptions and inconsistent wire feed speeds
Solution Approach 1:
The patent applies periodic pulsed current instead of continuous current during the welding process. The controller delivers current in discrete pulses with specific duty cycles, allowing the wire electrode to be heated and melted during active pulses while having cooling periods between pulses. This periodic action prevents continuous thermal accumulation at the contact tip interface, thereby reducing wire fusion while maintaining reliable arc establishment and welding process stability.
Solution Approach 2:
The patent dynamically adjusts current parameters (amplitude, pulse width, duty cycle) based on real-time welding conditions and wire feed speed. By changing the electrical parameters of the current supply, the system optimizes heat input to prevent wire fusion at the contact tip while ensuring sufficient heat for proper welding. This parameter control resolves the contradiction by adapting the energy input to match the specific welding requirements without causing harmful fusion.
2Productivity
If high current is applied to transfer molten wire, then welding progresses efficiently, but spot welds form between the wire and contact tip
Solution Approach 1:
The pulsed current delivery system allows high current to be applied intermittently rather than continuously. During each pulse, sufficient current is delivered to transfer molten wire efficiently, maintaining high productivity. Between pulses, the current is reduced or zero, allowing the wire at the contact tip interface to cool and preventing spot weld formation. This periodic high-current application achieves both efficient welding progression and prevention of harmful fusion.
Solution Approach 2:
The controller monitors wire feed speed and anticipates conditions that may lead to wire fusion. By adjusting current parameters in advance based on predicted welding conditions, the system prevents spot weld formation before it occurs. This preliminary adjustment of electrical parameters ensures that high current is applied only when conditions are favorable, maintaining productivity while preventing harmful effects.
3Productivity
If the wire feed speed increases, then productivity improves, but wire fusion to the contact tip becomes more likely due to insufficient cooling time
Solution Approach 1:
The pulsed current system synchronizes the pulse frequency and duty cycle with the wire feed speed. When wire feed speed increases, the controller adjusts the pulse frequency and width to provide adequate heating during each pulse while maintaining sufficient cooling time between pulses. This dynamic periodic action ensures that even at high wire feed speeds, the wire has opportunity to cool at the contact tip interface, preventing fusion and maintaining consistent wire feeding and reliable welding.
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 reduces the occurrence of spot welds, maintains consistent wire feed speeds, and improves the quality of molten metal droplet transfer by breaking free the wire from the contact tip before significant spring force builds up, thus preventing hard shorts and ensuring stable welding.
Implementation Method 1
a welding power supply to provide power to a welding torch for establishing an electrical arc between a metal cored welding wire and a workpiece to perform a weld
Implementation Method 2
establishing an electrical arc between a welding torch and a workpiece
Data Source
AI summary
Systems and methods are described to address issues associated with welding with cored wires. In certain processes, a welding wire may “stick” or fuse to a contact tip. To mitigate the negative effects of a wire fusing to a contact tip, a double pulse waveform is applied. A first pulse is applied at a first current level above a threshold current level required to transfer a ball of molten welding wire in a peak phase, and a second pulse is applied in the background phase at a second current level below the threshold current level to limit and/or eliminate fusion between the wire and the contact tip. In examples, the second current level is sufficient to dislodge a spot weld between the welding wire and the welding torch yet insufficient to transfer a ball of molten welding wire.