Pulse Arc Welding Wire Feed Control for Stable Arc Length
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Solution Overview
Problem
Conventional pulse arc welding methods face challenges in suppressing undercut and spattering during high-speed welding of mild steel, as they often result in high short-circuit currents and inadequate molten metal distribution, leading to poor weld quality.
Innovation Solution
A pulse arc welding device is controlled to maintain a constant arc length by varying the feeding speed of the welding wire between two speeds, one for the base current period and a higher speed for the peak current period, which helps in reducing spattering and undercut by ensuring stable molten droplet transfer and preventing short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If welding voltage is lowered and arc length is shortened to suppress undercut, then undercut is reduced, but spattering increases due to high short-circuit current
Solution Approach 1:
The patent applies dynamics by making the wire feeding speed variable rather than constant. The feeding speed is dynamically adjusted between a first feeding speed during the base current period and a second feeding speed during the peak current period, allowing the system to adapt to changing current conditions and prevent both undercut and spattering
Solution Approach 2:
The patent implements periodic action through pulse arc welding, where the current alternates between base current and peak current periods. This periodic current variation, combined with corresponding periodic changes in feeding speed, enables controlled molten droplet transfer that prevents short-circuiting and reduces spattering while maintaining adequate penetration
2Stability of the object's composition
If wire feeding speed is increased to maintain arc length during peak current, then arc length stability is improved, but control complexity increases
Solution Approach 1:
The patent employs feedback control where the wire feeding speed is automatically adjusted based on the current period detection. The control system monitors whether the system is in base current or peak current period and accordingly selects the appropriate feeding speed, creating a closed-loop control that maintains arc length stability without requiring complex manual intervention
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 results in improved welding quality with reduced spattering and undercut, maintaining a stable arc length and molten pool size, even at high-speed welding, thereby enhancing the appearance and integrity of the weld bead.
Implementation Method 1
generating an arc between the welding wire and the object by causing a welding current to flow through the welding wire
Implementation Method 2
causing a welding current to flow through the welding wire while feeding the welding wire to the object
Data Source
AI summary
A pulse arc welding device is controlled so as to alternately repeat a peak current period in which a welding current is a peak current and a base current period in which the welding current is a base current smaller than the peak current, feed a welding wire to an object at a feeding speed while the welding current flows through the welding wire, generate an arc between the welding wire and the object, and weld the object. So as to keep an arc length of the arc to be constant, in the base current period, the feeding speed is set to a first feeding speed and, in the peak current period, the feeding speed is set to a second feeding speed which is larger than the first feeding speed and corresponds to the first feeding speed. By this method, good welding quality with reduced spattering and suppressed undercut can be obtained.