Welding Electrode Cap Wear Detection Using Thermal Emissivity
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Solution Overview
Problem
Current methods for determining wear in resistance spot welding electrodes rely on preventive replacement schedules, which can lead to unnecessary replacements or defective welds due to uneven wear, as they do not accurately reflect the actual wear state of the electrode caps.
Innovation Solution
A method using thermal emission intensity measurement to determine the wear of welding electrode caps based on increased emissivity, employing direct or indirect infrared measurements with thermal cameras, allowing for predictive and proactive replacement or machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preventive replacement or machining of welding electrode caps is performed based on fixed schedules, then electrode availability is maintained, but unnecessary replacements occur and manufacturing costs increase
Solution Approach 1:
The patent replaces mechanical wear monitoring with optical measurement systems. Thermal cameras and infrared sensors detect emissivity changes on electrode cap surfaces, substituting physical inspection methods with non-contact optical detection to determine wear levels and trigger replacement only when necessary.
Solution Approach 2:
The patent monitors changes in thermal emissivity parameters of electrode cap surfaces. By measuring emissivity values and comparing them against threshold criteria, the system detects wear progression and determines optimal replacement timing, replacing electrodes based on actual condition rather than fixed schedules.
2Productivity
If welding electrode caps are used until complete wear, then productivity is maximized, but defective welds occur and quality decreases
Solution Approach 1:
The patent implements a feedback system where thermal emission measurements from electrode caps are continuously monitored and fed back to the control system. When emissivity changes indicate significant wear, the system alerts operators to replace electrodes before quality degradation occurs, maintaining weld quality while maximizing productive usage.
Solution Approach 2:
The patent performs preliminary detection of electrode wear using thermal imaging before quality defects manifest. By measuring emissivity changes in advance, the system enables proactive electrode replacement scheduling that prevents defective welds while extending electrode service life beyond traditional conservative schedules.
3Measurement precision
If thermal emission measurement is performed directly on electrode caps, then measurement precision is high, but the measurement system complexity increases
Solution Approach 1:
The patent introduces an intermediary reference surface with known emissivity properties adjacent to the electrode cap. Thermal cameras measure temperature differences between the electrode cap and reference surface, using the reference as a mediator to calculate electrode emissivity indirectly, simplifying the measurement system while maintaining precision.
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 enables accurate, contactless determination of wear levels during or outside the welding process, reducing unnecessary replacements and preventing defective welds by using thermal cameras to measure emissivity changes post-weld, aligning with predictive maintenance standards.
Implementation Method 1
The principle is based on determining a change in effective emissivity on a surface of welding electrodes
Implementation Method 2
thermal cameras working within wavelengths from 7 to 14 μm, and MWIR (Medium Wave InfraRed), i.e. thermal cameras working within wavelengths approximately from 3 to 5 μm
Implementation Method 3
For indirect measurements an infrared reflector with emissivity as close to zero as possible is used. So a procedure according to ČSN ISO 18434-1 for determining a reflected apparent temperature on the measured surface is used
Data Source
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Figure 3
AI summary
The invention concerns a method for determining a wear level of caps (4) of welding electrodes in resistance spot welding, where the thermal emission intensity from a surface of welding electrode replaceable caps (4) is measured by direct or indirect measurements and on the basis of the increased emissivity on the surface of welding caps (4) a level of their wear is determined, whereas the thermal emission intensity measurement is carried out immediately after a weld has been made. The above mentioned methods are carried out using a device comprising thermal camera (5) for scanning the thermal emission from a surface of welding electrode replaceable cap (4) connected to a computational device, or, possibly, an infrared reflector (7) is added.