Arc Start Pulse Control for 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 is introduced that includes a pulse period with pulse current energization followed by switching to the forward and reverse feed control, 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 (convex bead, poor match with base material)
Solution Approach 1:
The patent applies preliminary action by performing forward feed control during a pulse period at the arc start stage before transitioning to forward and reverse feed control. This preliminary forward feeding action ensures proper bead formation and match with the base material at the welding start portion, preventing the convex bead appearance and poor match that would otherwise occur when starting directly with reverse feed control.
Solution Approach 2:
The patent segments the welding start process into two distinct phases: a pulse period with forward feed control, and a subsequent period with forward and reverse feed control. This segmentation allows each phase to be optimized independently - the pulse period establishes proper bead appearance, while the subsequent phase maintains welding stability during steady-state operation.
2Manufacturing precision
If pulse current is energized during a pulse period with forward feed, then heat input is enhanced and bead appearance quality is improved, but the control complexity increases
Solution Approach 1:
The patent employs periodic action through pulse current energization during a defined pulse period at arc start. This periodic application of pulse current enhances heat input in a controlled manner, improving bead appearance quality by ensuring proper melting and fusion at the welding start portion, while the time-limited nature of the pulse period prevents excessive complexity in the control system.
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 method improves the quality of the weld bead at the welding start portion by enhancing heat input and stabilizing the welding state, resulting in a flat bead shape and improved match with the base material, reducing instability and smut generation.
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
AI summary
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 forward and reverse feed control is started from 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 pulse period Tp and/or a value of a welding voltage Vw during pulse period Tp.