Arc Start Control in Forward-Reverse Wire Feed Welding
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Solution Overview
Problem
The forward and reverse feed arc welding control method results in inferior bead appearance at the welding start portion, particularly when welding aluminum materials, leading to a convex bead and poor match between the bead and the base material at the toe portion.
Innovation Solution
An arc start control method that includes a pulse period with pulse current energization followed by initiation of forward and reverse feed control from the forward feed period, where the welding wire is fed forward during the pulse period, and the forward feed speed is set to maintain a continuous arc period, with adjustments based on pulse period length and welding voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If forward and reverse feed control is performed from the reverse feed period at arc start, then stable welding can be performed during steady welding period, but the bead appearance at welding start portion becomes inferior with convex shape and poor match with base material
Solution Approach 1:
The patent applies preliminary action by performing forward feed control during a pulse period before initiating the normal forward and reverse feed control. This preliminary forward feeding action ensures that the welding wire is properly positioned and the arc is stable before the alternating feed pattern begins, preventing the convex bead shape and poor toe portion match that occur when starting directly with reverse feed control.
Solution Approach 2:
The patent segments the arc start process into two distinct phases: a pulse period with forward feed control, and then the normal forward and reverse feed control period. This segmentation allows the welding process to be optimized for each phase separately - the pulse period establishes stable arc conditions, while the subsequent alternating feed pattern maintains stability during steady welding, thereby resolving the contradiction between start quality and steady-state stability.
2Reliability
If forward feed speed is increased during pulse period to maintain continuous arc period, then arc stability is improved, but control complexity increases
Solution Approach 1:
The patent applies dynamics by making the feed speed adjustable and variable during the pulse period based on welding voltage values. The feed speed is dynamically changed to maintain a continuous arc period, with the control system adapting the feed speed in real-time according to arc conditions. This dynamic control ensures arc continuity while managing complexity through voltage-based feedback.
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
Improves the quality of the weld bead at the welding start portion by enhancing heat input and maintaining a stable arc, resulting in a flat bead shape and improved match with the base material, thereby stabilizing the welding process.
Implementation Method 1
a pulse period during which a pulse current is energized for a plurality of number of times is provided
Implementation Method 2
generating an arc between the welding wire and a base material
Data Source
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AI summary
In forward and reverse feed arc welding in which a forward feed period and a reverse feed period of a feed speed are alternately switched, the bead appearance at a welding start portion is improved. In an arc start control method for forward and reverse feed arc welding in which forward and reverse feed control of alternately switching a feed speed Fw of a welding wire between a forward feed period and a reverse feed period is performed to generate a short circuit period and an arc period to perform welding, at arc start, a pulse period Tp during which a pulse current is energized for a plurality of number of times is provided, and thereafter the forward and reverse feed control is started from the forward feed period of the welding wire. During the pulse period Tp, a forward feed speed Fp of the welding wire is set so that the arc period is continuous. In addition, the forward feed speed Fp is changed based on a time length of the pulse period Tp and/or a value of a welding voltage Vw during the pulse period Tp.