Weld Start Detection Using Voltage Derivative Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional techniques for detecting weld start in arc welding systems are complex and prone to delays, making it difficult to quickly and accurately initiate the welding arc after the electrode tip contacts the workpiece.
Innovation Solution
The method involves sampling weld voltage values, computing their time derivatives to represent contact resistance, and increasing weld power when the voltage derivative values drop below a threshold, indicating a sufficient low resistance for arc initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional techniques are used to detect weld start, then the detection method is available, but the detection is complex and prone to delays
Solution Approach 1:
The patent extracts only the essential signal feature needed for weld start detection by computing the time derivative of voltage, isolating the critical information (contact resistance change) from the complex voltage signal. This simplifies the detection technique while maintaining accuracy.
Solution Approach 2:
The patent replaces complex conventional detection techniques with a mathematical computation approach (time derivative calculation), substituting mechanical or electronic complexity with algorithmic simplicity to achieve accurate weld start detection.
2Loss of time
If conventional techniques are used to detect weld start, then the detection method is available, but there is undesired delay in detecting weld start
Solution Approach 1:
The patent performs preliminary computation of the voltage time derivative continuously before weld start occurs, so that when contact happens, the system is already prepared to detect the resistance change immediately, eliminating detection delay without sacrificing accuracy.
3Reliability
If the electrode tip is held apart from the workpiece, then an open circuit is created, but weld start detection is delayed
Solution Approach 1:
The patent uses feedback from the voltage signal and its time derivative to continuously monitor the circuit state, providing real-time information about electrode contact without requiring the electrode to be held apart, thus eliminating detection delay while maintaining arc striking 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
This approach allows for quick and accurate detection of weld start, minimizing the delay between contact and arc initiation, and ensuring a rapid ramp-up of weld current to strike the arc.
Implementation Method 1
computing a time derivative of the voltage values to produce voltage derivative values that represent a contact resistance between the electrode tip and the workpiece
Implementation Method 2
increasing the weld power supplied to the electrode tip to initiate the arc on the workpiece
Data Source
AI summary
A method performed in a welding or cutting system configured to deliver weld power to an electrode tip extending from a torch to create an arc on a workpiece, comprises: sampling a sensed voltage indicative of a weld voltage provided to the electrode tip, to produce voltage values; computing a time derivative of the voltage values to produce voltage derivative values that represent a contact resistance between the electrode tip and the workpiece; and upon detecting a decrease in the voltage derivative values from above a time-derivative threshold to below the time-derivative threshold as an indication of a weld start event, increasing the weld power supplied to the electrode tip to initiate the arc on the workpiece.