Resistance Spot Welding Current Profile for Large Nuggets, Less Spatter
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Solution Overview
Problem
Existing resistance spot welding methods result in a poor ratio between alloy layer diameter and nugget diameter, leading to rapid nugget growth and spatter occurrence, especially at low welding pressures, and struggle to control spatter during main current application.
Innovation Solution
A resistance spot welding method involving preliminary current application with a maximum current value at start time followed by a stepwise decrease, and subsequent main current application with a constant value, to efficiently generate a large nugget while reducing spatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If current application time is extended in pulsation form to generate a large nugget, then nugget diameter increases, but alloy layer to nugget diameter ratio deteriorates and spatter occurs
Solution Approach 1:
The welding current is applied in periodic pulses with alternating high and low current values. The high current pulses generate heat to expand the nugget, while the low current pulses allow temperature stabilization to prevent spatter. This periodic action enables progressive nugget growth without causing harmful spatter effects.
Solution Approach 2:
The welding parameters (current value, pulse width, interval) are dynamically adjusted during the welding process based on the progression of nugget formation. The control device modifies current characteristics in real-time to optimize the balance between nugget expansion and spatter prevention throughout the welding cycle.
2Ease of operation
If welding pressure is reduced to 4 kN or lower for compact welding gun, then ease of operation improves, but nugget growth becomes rapid causing spatter
Solution Approach 1:
Periodic current pulses compensate for the reduced welding pressure by providing controlled thermal energy input. The alternating high and low current phases enable nugget growth under low pressure conditions without causing rapid, uncontrolled expansion that would lead to spatter.
3Productivity
If electric current rapidly increases during main current application period, then productivity improves, but control of spatter becomes difficult
Solution Approach 1:
Instead of a single rapid current increase, the welding process uses periodic current pulses that progressively build up heat. This approach maintains high productivity by continuing current application while preventing spatter through the low-current intervals that allow thermal equilibrium.
Solution Approach 2:
Preliminary current pulses are applied before the main welding current to preheat the welding zone and form an initial nugget. This preliminary action reduces the thermal shock when full current is applied, enabling faster welding without immediate spatter occurrence.
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 method effectively generates a large nugget while minimizing spatter by controlling the current value sequence, ensuring the alloy layer diameter exceeds the nugget diameter, thus optimizing the welding process.
Implementation Method 1
resistance spot welding method includes: placing on top of one another at least two steel plates including a plating layer of zinc as a main component or an Al—Si plating layer; sandwiching the at least two steel plates between a pair of electrodes; and performing preliminary current application between the pair of electrodes and then performing main current application, such that the steel plates that are adjacent to each other are melted and joined together
Data Source
AI summary
Provided is a resistance spot welding method capable of efficiently generating a nugget that is as large as possible while reducing the occurrence of spatter. The resistance spot welding method includes: placing on top of one another at least two steel plates including a plating layer of zinc as a main component or an Al—Si plating layer; sandwiching the at least two steel plates between a pair of electrodes; and performing preliminary current application between the pair of electrodes and then performing main current application. The resistance spot welding method performs the preliminary current application so as to include a current application pattern in which a current value of a welding current at a current application start time of the preliminary current application is set as a maximum value, and the current value sequentially decreases stepwise from the maximum value.