Arc Welding Current Modulation for Blowhole-Free Argon Welding
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Solution Overview
Problem
Consumable electrode arc welding processes using argon shielding gas at high welding currents (350 A to 600 A) often result in blowholes due to entrapped argon gas, which cannot be effectively prevented by conventional shielding measures, as the molten pool is not adequately vibrated to release trapped gases.
Innovation Solution
Implementing a method where the welding current is periodically varied between two conditions (one at 350 A or higher and another with a 50 A to 150 A range) at a frequency of 1 Hz to 5 Hz, combined with varying the voltage from 10 Hz to 1000 Hz, to create vibrations that dislodge entrapped air bubbles and stabilize the molten pool, thereby preventing blowholes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding current is set to 350 A to 600 A for high productivity welding, then welding efficiency is improved, but blowholes occur due to entrapped argon gas in the molten pool
Solution Approach 1:
The patent applies periodic action by superimposing a high-frequency alternating current (10 Hz to 1000 Hz) on the welding current. This periodic current variation creates corresponding vibrations in the molten pool at the same frequency, which effectively dislodges and expels entrapped argon gas bubbles, preventing blowhole formation while maintaining high welding current for productivity.
Solution Approach 2:
The patent utilizes mechanical vibration by generating high-frequency current fluctuations that induce corresponding vibrations in the molten pool. These vibrations create turbulent flow patterns that enhance gas bubble detachment and rise to the surface, eliminating the harmful effect of entrapped gas while preserving the high welding current necessary for efficient welding.
2Reliability
If shielding gas flow is increased to prevent atmospheric contamination, then shielding effectiveness is improved, but argon gas becomes more easily entrapped in the molten pool causing blowholes
Solution Approach 1:
The patent resolves this contradiction by applying periodic high-frequency current modulation that creates corresponding vibrations in the molten pool. This periodic action maintains the beneficial shielding effect of argon gas while simultaneously generating turbulent flow patterns that prevent gas entrapment, allowing both high shielding effectiveness and blowhole-free welding.
Solution Approach 2:
The patent uses mechanical vibration induced by high-frequency current variation to counteract the harmful effect of increased shielding gas flow. The vibrations create continuous motion in the molten pool that facilitates gas bubble escape, thereby maintaining reliable shielding protection without suffering from argon entrapment and blowhole formation.
3Object-affected harmful factors
If welding current is varied frequently at several tens of Hz to vibrate molten metal, then blowhole suppression is improved, but welding stability deteriorates at high current (350 A to 600 A)
Solution Approach 1:
The patent applies periodic action at an optimized frequency range of 10 Hz to 1000 Hz, which is lower than the several tens of Hz mentioned in prior art. This frequency range effectively vibrates the molten pool to suppress blowholes while causing less disturbance to the welding process stability, particularly at high welding currents of 350 A to 600 A.
Solution Approach 2:
The patent employs parameter changes by adjusting the frequency of current variation to an optimal range (10 Hz to 1000 Hz) that balances two competing requirements: generating sufficient vibration to expel gas bubbles and maintaining welding process stability. This parameter optimization resolves the contradiction between blowhole suppression and welding stability.
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 effectively suppresses the occurrence of blowholes in consumable electrode arc welding at high currents, ensuring deep penetration while maintaining a stable molten pool and reducing bead distortion, even when welding stainless steel.
Implementation Method 1
consumable electrode arc welding method
Implementation Method 2
superimposing a high-frequency alternating current on the welding current... creates vibrations that dislodge entrapped air bubbles
Data Source
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AI summary
A consumable electrode arc welding method using a shielding gas containing argon comprises: setting a first welding condition in which a first welding current is supplied to a welding wire (5); and setting a second welding condition in which a second welding current is supplied to a welding wire (5). The first welding condition and the second welding condition are welding conditions in which a reference current of the welding current is 350 A or higher and a current variation range is from 50 A to 150 A, and the first welding condition and the second welding condition are switched at a cycle of a frequency ranging from 1 Hz to 5 Hz.