Spot Welding Spatter Detection from Current Pulse Width Shifts
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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 voltage detection line is added to detect spatter occurrence, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The welding power supply system uses its own existing current detection capability to detect spatter occurrences by monitoring pulse width changes, eliminating the need for separate voltage detection lines. The system serves itself by utilizing already-present sensors and control circuitry for a dual purpose.
Solution Approach 2:
The existing current detection system, originally designed for welding process control, is made multi-functional by also enabling spatter detection through pulse width analysis. This single system performs both welding control and quality monitoring functions.
2Reliability
If voltage detection line is added to detect spatter occurrence, then spatter detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The welding power supply system uses its own existing current detection capability to detect spatter occurrences by monitoring pulse width changes, eliminating the need for separate voltage detection lines. The system serves itself by utilizing already-present sensors and control circuitry for a dual purpose.
Solution Approach 2:
The pulse width of the welding current serves as an intermediary parameter that reflects both the welding process state and spatter occurrence. By monitoring this intermediate characteristic, the system detects spatter without requiring direct voltage measurement near the electrode chips.
3Device complexity
If pulse width measurement method is used to detect spatter, then device complexity is reduced, but measurement precision may be affected
Solution Approach 1:
The system continuously monitors the pulse width of welding current and compares it against expected values, using feedback control to detect deviations indicating spatter. The control unit adjusts and analyzes pulse width variations in real-time to maintain detection accuracy.
Solution Approach 2:
The system detects spatter by monitoring changes in the pulse width parameter of the welding current. When spatter occurs, the electrical characteristics change, causing measurable variations in pulse width that indicate the presence of spatter without requiring additional hardware.
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 based on pulse width comparisons, reducing the need for additional hardware and improving welding quality assessment.
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
a welding current having a pulse-shaped waveform is supplied to a plurality of metal plates over a plurality of cycles in a state in which the plurality of metal plates is sandwiched by a pair of electrodes
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.