Spot Welding Spatter Detection via Pulse Width Difference
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Solution Overview
Problem
Conventional spatter detection methods in spot welding require an additional voltage detection line, increasing costs and complexity.
Innovation Solution
A spatter detection method that measures pulse width differences in pulse-shaped welding current waveforms to detect spatter occurrences without the need for a new voltage detection line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage detection line is provided to detect voltage near electrode chips for spatter detection, then spatter detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses the welding current waveform itself as an intermediary to detect spatter. Instead of adding a separate voltage detection line, the method analyzes changes in the pulse width of the welding current waveform, which naturally reflects spatter occurrences. The welding current serves as both the processing tool and the detection signal source.
Solution Approach 2:
The welding current waveform provides self-detection capability. By monitoring the pulse width variations of the welding current that is already flowing through the workpiece, the system detects spatter without requiring external detection infrastructure. The welding process itself generates the detection signal.
2Device complexity
If pulse width measurement is used to detect spatter, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The system continuously monitors the welding current waveform and compares the measured pulse width against reference values or thresholds. When the pulse width deviation exceeds a predetermined threshold, spatter is detected. This feedback mechanism ensures accurate spatter detection while maintaining simple device structure.
Solution Approach 2:
The patent detects spatter by measuring changes in the pulse width parameter of the welding current waveform. Instead of measuring voltage directly, the system monitors the temporal characteristics (pulse width) of the current, which changes when spatter occurs. This parameter transformation enables simple yet effective detection.
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 detection of spatter occurrences and estimation of product quality based on detection timing, reducing the need for visual inspections and minimizing man-hours for post-welding inspection.
Implementation Method 1
power is distributed between a pair of electrode chips in a state in which the plurality of metal plates as workpieces is sandwiched between the pair of electrode chips, and in this manner, a nugget is generated between the plurality of metal plates to weld the plurality of metal plates
Implementation Method 2
supplying the welding current having a pulse-shaped waveform by alternately executing a step of maintaining the welding current within a set peak current range and a step of decreasing the welding current from the peak current range toward a bottom current
Data Source
AI summary
A spot welding method includes supplying a welding current having a pulse-shaped waveform to a workpiece by alternately executing a step of maintaining the welding current within a set peak current range and a step of decreasing the welding current from the peak current range toward a bottom current and then increasing the welding current toward the peak current range when an effective value of the welding current reaches a set target range for a plurality of cycles. The spatter detection method includes measuring a pulse width IW(1), IW(2), . . . in each cycle of the pulse-shaped waveform and detecting the occurrence of spatter when a pulse width difference D(M)=IW(M)−IW(M−1) between a pulse width IW(M) in a target cycle (M-th cycle) and a pulse width IW(M−1) in a cycle immediately before the target cycle exceeds a width threshold value Dth.