Adaptive Resistance Spot Welding Under Shunting and Sheet Gaps
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Solution Overview
Problem
Existing resistance spot welding methods fail to consistently achieve a stable nugget diameter without expulsion, especially when disturbances such as current shunting or significant sheet gaps occur, due to variations in electrode wear and disturbance effects.
Innovation Solution
A resistance spot welding method involving test welding under multiple conditions to store time variation curves of heat generation, with adaptive control adjusting current passage based on preliminary and main current passages to match target heat patterns, effectively addressing disturbances and ensuring a desired nugget diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the same welding current is used throughout electrode life, then the initial welding quality is maintained, but the nugget diameter decreases as electrodes wear
Solution Approach 1:
The welding current is dynamically adjusted based on the number of welding operations performed. The control unit increases the welding current in steps as electrodes wear, compensating for decreased current density and maintaining consistent nugget diameter throughout electrode service life
Solution Approach 2:
The system uses feedback from the operation count to automatically adjust welding parameters. By monitoring the number of welding operations and comparing it against predetermined thresholds, the control unit automatically modifies the welding current to maintain optimal welding conditions without manual intervention
2Manufacturing precision
If a high welding current is set to compensate for current shunting, then nugget diameter requirement is met, but expulsion occurs under disturbance conditions
Solution Approach 1:
The welding current is applied in periodic pulses rather than continuously. Multiple current pulses are delivered with intervals between them, allowing heat to distribute more evenly and preventing excessive localized heating that causes expulsion, while still achieving the required nugget diameter even with current shunting
Solution Approach 2:
The welding current magnitude is dynamically adjusted based on detected disturbance conditions. When current shunting or sheet gaps are detected, the control unit modifies the current profile to compensate for heat loss while maintaining safe temperature levels to prevent expulsion
3Extent of automation
If predetermined welding current patterns are used, then welding automation is achieved, but time and cost are required to derive patterns for numerous conditions
Solution Approach 1:
The welding system automatically determines optimal current patterns by monitoring actual welding conditions and operation count, eliminating the need for manual pattern derivation. The control unit self-adjusts parameters based on feedback from the welding process itself, reducing setup time and enabling adaptation to new conditions without extensive testing
Solution Approach 2:
Instead of creating fixed patterns for each condition, the system uses parameter changes based on operation count and detected conditions. A single base pattern is modified dynamically by adjusting current magnitude and pulse timing based on electrode wear and disturbance detection, reducing the need to derive multiple predetermined patterns
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 method stabilizes nugget diameter and prevents expulsion even under significant disturbance conditions, improving operating efficiency and yield rates in continuous welding processes like vehicle manufacturing.
Implementation Method 1
heat generated from the resistance to the flow of the high welding current is used to obtain a spot weld
Data Source
AI summary
A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding. The test welding is performed under each of two or more welding conditions. In the actual welding, preliminary current passage is performed by constant current control in the same current pattern as in the preliminary current passage of the test welding, an electrical property between the electrodes in the preliminary current passage in the actual welding and an electrical property between the electrodes stored in the preliminary current passage in the test welding are compared for each welding condition to set a target in main current passage in the actual welding, and thereafter adaptive control welding is performed to control a current passage amount as the main current passage.