Spot Welding Spatter Detection from Pulse-Pause Current Decay
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Solution Overview
Problem
Existing spatter detection methods in spot welding require frequent replacement of voltage detection lines near electrode chips due to high temperatures, increasing costs and cycle time, and are not capable of detecting spatter using existing sensors without additional infrastructure.
Innovation Solution
A spatter detection method that utilizes a current sensor to determine the occurrence of spatter by comparing current detection values during power distribution pauses across cycles, leveraging the RL series circuit characteristics of the welding system to detect changes in welding current falling characteristics without the need for additional voltage detection lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage detection line is provided in the vicinity of electrode chips to detect spatter, then spatter detection accuracy is improved, but the line needs frequent replacement due to high temperature exposure, increasing costs and cycle time
Solution Approach 1:
The invention extracts the voltage detection function from the high-temperature vicinity of electrode chips and relocates it to a cooler position in the welding circuit. By detecting voltage at a location远离 the electrodes and calculating resistance using R=U/I, the system maintains spatter detection accuracy while eliminating the need for frequent line replacement due to thermal damage
Solution Approach 2:
The invention introduces an intermediary calculation method using the relationship R=U/I. Instead of directly measuring resistance at the electrode chips, the system measures voltage at a remote location and combines it with current measurements to indirectly determine workpiece resistance, thereby detecting spatter without exposing detection lines to high temperatures
2Adaptability or versatility
If a voltage detection line is provided in the vicinity of electrode chips to detect spatter, then spatter detection capability is improved, but device complexity and cost increase due to additional infrastructure
Solution Approach 1:
The invention makes existing sensors serve multiple functions. The current sensor, originally used only for welding current control, is additionally utilized for spatter detection by analyzing current characteristics during power distribution pauses. This multi-functionality eliminates the need for separate detection infrastructure while maintaining spatter detection capability
Solution Approach 2:
The welding system performs self-diagnosis for spatter detection using its own existing sensors and control infrastructure. By analyzing the natural current decay characteristics during power distribution pauses, the system detects spatter without requiring external detection devices, thereby reducing device complexity and cost
3Manufacturing precision
If pulse-shaped welding current is supplied over multiple cycles, then welding quality is improved, but spatter detection becomes more difficult due to varying current characteristics
Solution Approach 1:
The invention utilizes the periodic power distribution pauses inherent in multi-cycle pulse welding. During these pause intervals, the current naturally decays following RL circuit characteristics, creating a predictable periodic pattern. By analyzing the current decay during these regular pauses and comparing across cycles, the system can detect spatter despite the varying current characteristics
Solution Approach 2:
The system implements feedback by continuously monitoring current characteristics during power distribution pauses and comparing them across cycles. When deviations exceed a threshold, the system identifies spatter occurrence and can adjust subsequent welding parameters, thereby maintaining welding quality while enabling detection amidst varying current characteristics
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 accurate and cost-effective spatter detection using existing sensors, reducing the need for frequent line replacements and maintaining high detection accuracy across varying workpiece materials and thicknesses.
Implementation Method 1
power distribution control and a power distribution pause over a plurality of cycles while the workpiece is sandwiched and pressurized by the pair of electrodes
Implementation Method 2
a current sensor configured to detect a current flowing through the pair of electrodes
Data Source
AI summary
A spatter detection method is a method for detecting an occurrence of spatter at the time of joining a workpiece using a spot welding apparatus including a pair of electrode chips, a welding power circuit connected to the pair of electrode chips, and a current sensor configured to detect a current flowing through the pair of electrode chips. A spot welding method using the spot welding apparatus includes supplying a pulse-shaped welding current to the workpiece, the pulse-shaped welding current being generated when the welding power circuit alternately repeats power distribution control and a power distribution pause over a plurality of cycles while the workpiece is sandwiched and pressurized by the pair of electrode chips. The spatter detection method includes determining, based on a current detection value detected by the current sensor in a power distribution pause section for each cycle, whether or not the spatter occurs.