Spot Welding Pulse Control for Oxide Film Pre-Conditioning
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Solution Overview
Problem
Existing spot welding machines face challenges with non-conducting oxide films on workpieces, leading to high resistance and overheating, which are not adequately addressed by static solutions that do not adapt to different types of workpieces and electrode assemblies.
Innovation Solution
A spot welding machine with a control unit that applies adaptive pre-conditioning welding pulse portions to measure and adjust voltage and current, ensuring the resistance is below a predetermined threshold before initiating the actual welding process, allowing for iterative pre-conditioning and flexible settings based on workpiece conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If large, flat welding electrodes are used to reduce current density and prevent overheating, then electrode/workpiece overheating is reduced, but manufacturing precision deteriorates due to undesired consequences
Solution Approach 1:
The patent applies preliminary action by performing pre-conditioning pulses before the actual welding process. These pre-conditioning pulses remove oxide films and reduce contact resistance at the electrode-workpiece interface, preventing overheating during welding without requiring larger electrode surfaces, thus maintaining welding precision.
2Reliability
If static pre-conditioning solutions are used to remove oxide films, then resistance reduction is achieved, but adaptability deteriorates for different workpiece and electrode types
Solution Approach 1:
The patent implements dynamics by making the pre-conditioning process adaptive and dynamic. The control unit adjusts pre-conditioning parameters (voltage, current, pulse duration) based on real-time measurements of contact resistance and workpiece characteristics, enabling the system to adapt to different workpiece and electrode assemblies while effectively removing oxide films.
Solution Approach 2:
The patent applies feedback by using measurement means to continuously monitor contact resistance during pre-conditioning. The control unit receives this feedback and adjusts pre-conditioning parameters accordingly, creating a closed-loop control system that ensures effective oxide removal while adapting to varying workpiece conditions.
3Manufacturing precision
If iterative pre-conditioning with multiple pulse portions is applied to ensure resistance below threshold, then weld quality improves, but process time increases
Solution Approach 1:
The patent applies partial action by using multiple pulse portions with varying intensities. The first pulse portion applies higher voltage/current to break down oxide films, followed by subsequent pulse portions with reduced intensity to fine-tune contact resistance. This staged approach achieves weld quality requirements while minimizing total pre-conditioning time compared to continuous high-intensity pulsing.
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 approach ensures effective pre-conditioning, reducing resistance and preventing overheating, resulting in improved weld quality by dynamically adjusting the pre-conditioning process based on real-time measurements and workpiece characteristics.
Implementation Method 1
a transformer having a primary input side and secondary output side, the secondary output side connected to the pair of electrodes
Implementation Method 2
receive, from measurement means arranged at the secondary output side of the transformer, an indication of a first voltage and a first current applied in relation to the first welding pulse portion, determine a first resistance value based on the indication of the first voltage and the first current
Implementation Method 3
electric welding current is supplied through the material via the welding electrodes
Data Source
AI summary
The present disclosure generally relates to a welding machine adapted for performing a spot welding process on a workpiece, wherein the welding machine is specifically adapted for automatically applying pre-conditioning a welding pulse portion to the workpiece prior to performing the spot welding process. The present disclosure also relates to a corresponding method and computer program product.