Joining Process Monitoring via Feature Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing joining processes for forming composite products, such as blister packs, face quality issues due to foreign bodies between substrates during the sealing process, which current monitoring methods, relying on threshold force comparisons, cannot detect with absolute certainty.
Innovation Solution
A computer-implemented method that acquires and evaluates measurement data from the pressing process to extract multiple features representing the quality of the joining process, determining an evaluation indicator to assess the process quality and control the pressing device based on this evaluation, allowing for improved detection of faulty executions and reduced defective products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If threshold value comparison of pressing force is used for monitoring, then the monitoring method is simple, but the detection accuracy and reliability of quality problems cannot be ensured with absolute certainty
Solution Approach 1:
The pressing force curve is segmented into multiple characteristic regions (pre-loading, pressing loading, post-loading) and further divided into multiple evaluation features within each region. This segmentation allows detailed analysis of specific process phases and identifies quality issues that would be missed by a single threshold comparison, thereby improving detection reliability without significantly increasing system complexity.
Solution Approach 2:
The monitoring approach transitions from one-dimensional threshold comparison to multi-dimensional feature extraction. Multiple evaluation features are extracted from different regions of the pressing force curve, and these features are combined into an evaluation indicator that considers the entire process profile. This dimensional expansion enables detection of subtle quality variations that single-threshold methods cannot capture.
2Reliability
If multiple features are extracted and evaluated to improve detection accuracy, then the reliability of quality assessment improves, but the complexity of the monitoring system increases
Solution Approach 1:
The evaluation features are pre-defined and pre-processed during the monitoring setup phase. The pressing force curve is pre-divided into characteristic regions, and the specific features to be extracted (max force, threshold exceedances, area integrals) are predetermined. This preliminary preparation simplifies the real-time monitoring process, as the system only needs to extract predefined features rather than dynamically determining what to measure, thus reducing operational complexity while maintaining high reliability.
Solution Approach 2:
The system continuously monitors the pressing process and provides feedback through the evaluation indicator, which compares extracted features against predefined criteria. This feedback mechanism allows the system to automatically identify quality issues and trigger appropriate responses. The feedback loop operates efficiently by using pre-established evaluation rules, avoiding the need for complex real-time decision-making algorithms.
3Measurement precision
If threshold-based monitoring is used, then the system is less sensitive to measurement variations, but it cannot detect subtle quality issues such as partial foreign bodies or improper product positioning
Solution Approach 1:
The monitoring method applies local quality analysis by examining specific regions of the pressing force curve (pre-loading, pressing loading, post-loading) and extracting features specific to each region. This allows the system to detect subtle variations in different process phases, such as partial foreign bodies that affect only certain portions of the sealing process. By focusing on local characteristics rather than relying on a single overall threshold, the system achieves both robustness and precision.
4Strength
If the pressing force is increased to ensure proper joining, then the joining quality improves, but the risk of detecting false positives due to thermal expansion or measurement distortions increases
Solution Approach 1:
The monitoring system dynamically adapts to the pressing process by continuously extracting features from the evolving pressing force curve and comparing them against predefined criteria. Rather than using a static threshold, the system evaluates the dynamic characteristics of the force application across different phases. This dynamic approach allows the system to distinguish between legitimate joining variations and false positives caused by thermal expansion or measurement distortions, maintaining high reliability even when pressing forces are increased.
Data Source
AI summary
A method for automatically monitoring a joining process for connecting a plurality of substrates to form a composite product under application of pressure from a pressing device comprises: acquiring measurement data which represent respective measurement values of a measurement variable for various working positions assumed by the pressing device during the application of pressure, which variable indicates a pressing force acting on the substrates during the respective working position or a variable that is dependent thereon; evaluating the acquired measurement data in order to extract therefrom a plurality of different features which each individually and/or jointly represent at least one characteristic property of a course of the measurement variable represented by the measurement data as a function of the working positions of the pressing device or a variable corresponding to the working positions; determining an evaluation indicator as a function of the extracted features; evaluating the joining process based on a juxtaposition of the evaluation indicator with an evaluation reference, by generating an evaluation result resulting from the juxtaposition, which characterizes a quality of the joining process or of the composite product produced thereby; and controlling the pressing device and/or further processing of the composite product produced by the joining process depending on the evaluation result.