Resistance Welding Curve Evaluation for Precise Quality Control
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Solution Overview
Problem
Current quality control methods for resistance-welded components, particularly in capacitor discharge welding, are inadequate for precise and flexible evaluation of welding parameters, leading to rough characterization and potential defects in high-load components.
Innovation Solution
A method and device for evaluating welding parameters such as welding current, voltage, force, and melting path by analyzing the slope and gradient of recorded curves, allowing for individual and precise quality assessment without relying on envelope curves, enabling detection of small deviations and irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional quality control methods using envelope curves or individual peak evaluation are used, then the device complexity is low and ease of operation is high, but the measurement precision and manufacturing precision are insufficient
Solution Approach 1:
The welding parameter curve is segmented into multiple evaluation points (peaks, valleys, inflection points) rather than evaluating the entire curve as a single entity. This allows precise local analysis of critical features while maintaining manageable system complexity through focused evaluation at discrete points.
Solution Approach 2:
The patent evaluates only the most critical portions of the welding curve (peaks, valleys, inflection points) rather than analyzing every data point. This partial action approach achieves sufficient measurement precision for quality control without requiring excessive computational resources or system complexity.
2Reliability
If random sampling for quality control is performed, then the device complexity and measurement effort are reduced, but the reliability and measurement precision of quality control are insufficient
Solution Approach 1:
The system performs preliminary evaluation of welding parameters during the welding process itself by analyzing the welding curve in real-time. This allows quality assessment to be built into the manufacturing process rather than requiring separate post-process sampling and testing, thereby improving reliability without significant time loss.
3Manufacturing precision
If comprehensive quality control is implemented for each welded component, then the reliability and manufacturing precision are improved, but the productivity decreases due to increased time consumption
Solution Approach 1:
The patent replaces physical mechanical testing methods (tensile tests, compression tests, metallographic analysis) with electrical/electronic measurement and analysis of welding parameter curves. This substitution enables rapid, non-destructive quality assessment that maintains high manufacturing precision while significantly reducing the time required compared to traditional mechanical testing, thereby preserving productivity.
4Measurement precision
If envelope curves with tolerance ranges are used for quality control, then the ease of operation is high and device complexity is low, but the measurement precision is insufficient for detecting small deviations
Solution Approach 1:
Instead of applying a uniform tolerance envelope across the entire welding curve, the patent applies different evaluation criteria and precision levels to different local features of the curve (peaks, valleys, inflection points). Each feature is analyzed with appropriate precision tailored to its specific quality requirements, enabling detection of small deviations without requiring overly complex global evaluation systems.
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 provides a more accurate and reliable quality control, enabling the identification of defective components during production, automatic ejection of rejected parts, and adaptation to various welding processes, improving the characterization of welded components and reducing waste.
Implementation Method 1
high charging voltages of the capacitors up to 4,000V
Implementation Method 2
a large amount of energy (up to 160 kJ, e.g., 30 kJ) is transferred across the contact surface, thereby achieving local melting
Implementation Method 3
resistance welding, especially capacitor discharge welding (CDW), is a process used to manufacture all kinds of semi-finished products
Implementation Method 4
a large amount of energy (up to 160 kJ, e.g., 30 kJ) is transferred across the contact surface, thereby achieving local melting
Implementation Method 5
two components are pressed together with a predefined force (e.g., 5 to 300 kN, especially 20 to 100 kN)
Implementation Method 6
thereby achieving local melting (especially of an annular boss) and a metallurgical bond
Implementation Method 7
resistance welding, especially capacitor discharge welding (CDW), is a process used to manufacture all kinds of semi-finished products
Data Source
Figure 1A~1D
Figure 2A~2D
Figure 3A~3D
AI summary
Quality analysis is advantageous in numerous welding processes, particularly in resistance welding. The invention relates to a quality evaluation method for characterizing resistance-welded components by evaluating at least one welding parameter from the group consisting of: welding current, welding voltage, contact force, resistance, and relative displacement; wherein a recorded profile of the welding parameter to be evaluated is provided as a curve (PC) of the respective welding parameter.According to the invention, the curve (PK) is evaluated by reading at least one characteristic value (Kl, Kn) of the respective curve as a function of time and optionally also as a function of at least one further welding parameter; comparing the characteristic value with at least one target value (V1, Vn) for the characteristic value, wherein the target value is defined based on the recorded course or gradient of the welding parameter to be evaluated; and evaluating the quality of the welded component (1) based on the comparison of the characteristic values, in particular with regard to the magnitude of any deviation of the characteristic value from the target value. This also provides good accuracy and reproducibility. The invention further relates to corresponding devices, computer program products, and uses.