AC Arc Welding Wire Feed Control for Bead Shape
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Solution Overview
Problem
In consumable electrode AC arc welding, it is challenging to independently set the penetration depth and reinforcement area of the bead shape due to the significant variation in welding current average value when adjusting the EN ratio, requiring extensive preparatory tests and considerable time.
Innovation Solution
A feed control method for consumable electrode AC arc welding that involves setting distinct wire feed rates for electrode positive and negative polarity periods based on specific welding current settings, allowing for independent control of the EN ratio and welding current average value, with optional gradient transitions to prevent feed rate undershooting and overshooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the EN ratio is adjusted to change wire welding characteristics, then the bead shape (reinforcement area) can be modified, but the welding current average value changes significantly, causing penetration depth to change as well
Solution Approach 1:
The wire feed rate control is segmented into polarity-dependent parameters: a first wire feed rate for electrode positive polarity and a second wire feed rate for electrode negative polarity. This segmentation allows independent optimization of welding parameters for each polarity period, enabling separate control of penetration depth (主要通过EP期控制) and reinforcement area (主要通过EN期控制), thereby resolving the coupling effect that previously prevented independent parameter setting.
2Device complexity
If the wire feed rate is kept constant independent of polarity, then the control system is simple, but it is impossible to independently control penetration depth and reinforcement area
Solution Approach 1:
The wire feed rate is transformed from a static constant value to a dynamic parameter that changes according to polarity. The control system dynamically switches between the first wire feed rate during electrode positive polarity periods and the second wire feed rate during electrode negative polarity periods. This dynamic adjustment enables versatile bead shape control while maintaining relatively simple control logic through polarity-based switching.
3Speed
If the wire feed rate is switched abruptly between polarities, then the control response is fast, but feed rate undershooting and overshooting occur, destabilizing the welding state
Solution Approach 1:
A gradient transition mechanism is implemented to cushion the abrupt changes in wire feed rate during polarity switching. Instead of instantaneous switching, the wire feed rate changes gradually from the first feed rate to the second feed rate (or vice versa) over a transition period. This beforehand cushioning prevents undershooting and overshooting, maintaining welding state stability while preserving fast control response capability.
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
Enables easy and precise setting of the bead shape by allowing independent control of the reinforcement area and penetration depth, reducing the need for extensive preparatory tests and improving the stability of the welding state during polarity switching.
Implementation Method 1
welding current Iw flows... welding voltage Vw is applied between the welding wire and the base material
Implementation Method 2
consumable electrode AC arc welding... arc period Ta... welding voltage Vw reaches the arc voltage value
Data Source
AI summary
A feed control method is provided for consumable electrode AC arc welding, in which the welding wire is fed at a predetermined wire feed rate, and a welding voltage applied to an arc is switched in alternation between positive polarity and negative polarity. In the method, a welding current setting signal is generated. The wire is fed at a first feed rate during a period of the positive polarity, whereas the wire is fed at a second feed rate different from the first feed rate during a period of the negative polarity.