Contactless Arc Ignition Using Alternating-Polarity Pulse Sequences
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Solution Overview
Problem
Existing welding technologies face challenges in reliably igniting and maintaining arcs between electrodes and workpieces, especially on smooth or polished surfaces, due to variations in material properties and surface conditions, leading to frequent misfires and suboptimal weld quality.
Innovation Solution
A method and device for contactless arc ignition using a sequence scheme of ignition voltage pulses with alternating polarities, allowing for automatic adjustment of polarity and pulse parameters to ensure reliable ignition without operator intervention, utilizing a welding device with a supply unit that generates a sequence of pulses to maintain the arc after initial ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ignition at the positive terminal is used, then arc ignition reliability is improved on certain surfaces, but ignition becomes more difficult on smooth polished surfaces and the arc may extinguish upon polarity reversal
Solution Approach 1:
The system dynamically switches between different ignition polarities (positive and negative) and sequences based on detected arc ignition status and surface conditions. The control unit adjusts the ignition strategy in real-time, transitioning from a fixed polarity approach to a dynamic, adaptive approach that responds to actual welding conditions.
Solution Approach 2:
The invention changes the polarity parameter of the ignition voltage pulse based on detected conditions. The system attempts ignition with one polarity, and upon failure or arc extinguishment, switches to the opposite polarity for the next ignition attempt. This parameter change allows adaptation to different surface conditions without requiring manual intervention.
2Device complexity
If a single ignition polarity is used, then the ignition process is simple, but misfires occur frequently on smooth surfaces and weld quality deteriorates
Solution Approach 1:
The system implements periodic alternation between positive and negative ignition polarities in a defined sequence. When ignition fails with one polarity, the system automatically switches to the other polarity for the next attempt. This periodic switching between opposite actions (positive/negative polarity) ensures reliable ignition across different surface conditions while maintaining automated operation.
3Reliability
If manual adjustment of ignition settings is required, then optimal settings can be found, but operator intervention is needed and trial-and-error increases time consumption
Solution Approach 1:
The welding device performs self-adjustment of ignition settings by automatically detecting ignition success or failure and switching polarities accordingly. The control unit monitors the welding process and autonomously selects the appropriate ignition polarity without requiring operator intervention. This self-service capability eliminates manual trial-and-error adjustment while maintaining optimal ignition reliability.
4Device complexity
If ignition parameters are fixed, then the control system is simple, but parameters may become suboptimal when welding conditions change during the process
Solution Approach 1:
The system incorporates feedback mechanisms that monitor arc ignition status and welding conditions in real-time. Based on this feedback, the control unit automatically adjusts ignition parameters, specifically switching between positive and negative polarities. This feedback loop enables the system to adapt to changing conditions such as different surface roughness areas encountered during welding of long seams, maintaining optimal performance without complex manual reconfiguration.
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
The solution ensures consistent and reliable arc ignition across various materials and surface conditions, reducing misfires and improving weld quality by automatically adapting to optimal ignition settings through a sequence scheme that can be defined or learned based on material properties and welding conditions.
Implementation Method 1
an ignition voltage pulse can be applied between the electrode and the workpiece. This ionizes the area between the electrode and the workpiece, causing the arc to ignite in the ionized region
Implementation Method 2
a welding voltage is applied to maintain the arc during welding
Data Source
Figure 1
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Figure 4
AI summary
This application relates to a method and a welding device (6) for contactlessly striking an arc (1) between an electrode (2) of a welding head (3) and a material surface (4) of a workpiece (5). A first ignition voltage pulse with a first or second polarity is generated between the electrode (2) and the material surface (4). After being struck and, where applicable, after a polarity reversal, the arc (1) is maintained with the second polarity or with an alternating polarity. In the event of an ignition failure, after the first ignition voltage pulse a sequence of ignition voltage pulses is generated according to a sequence schema until successful striking of the arc (1), wherein the sequence schema comprises ignition voltage pulses with the first polarity and ignition voltage pulses with the second polarity, and wherein an ignition pause is provided between ignition voltage pulses with the first polarity and ignition voltage pulses with the second polarity.