Spot Weld Head Accelerometer for Real-Time Defect Detection

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Solution Overview

Problem

Existing resistance spot welding technologies lack efficient methods to detect welding defects in real-time, particularly in opposed and parallel gap configurations, which can lead to substandard welds and increased production costs.

Innovation Solution

The apparatus incorporates a resistance spot weld head with integrated processing circuits and accelerometers to gather acceleration data during welding. This data is analyzed to determine if the welding process has resulted in defects by comparing acceleration values to predetermined threshold ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional resistance spot welding is performed without real-time monitoring, then the welding process is simple and fast, but welding defects cannot be detected and substandard welds are produced

Engineering Contradiction:
Improveweld qualityVSAvoidwelding system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the accelerometer sensor directly with the welding electrode assembly, merging the monitoring function into the existing welding tool. This integration allows real-time acceleration data collection during welding without requiring separate monitoring equipment, thereby improving weld quality while minimizing system complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system implements real-time feedback by continuously monitoring acceleration data during the welding process and comparing it against predetermined thresholds. When abnormal acceleration patterns indicating defects are detected, the system can immediately identify and correct issues, ensuring high weld reliability

Inventive Principle:
Principle #23Feedback

2Reliability

If real-time welding defect detection is implemented using sensors and processing circuits, then welding quality improves, but the device complexity and cost increase

Engineering Contradiction:
Improveweld qualityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The welding system performs self-diagnosis by using the accelerometer to monitor its own operation during welding. The processing circuits analyze acceleration data generated during normal welding operations to automatically detect defects, allowing the system to monitor itself without requiring external inspection equipment or complex additional manufacturing processes

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces traditional post-weld inspection methods with real-time electronic monitoring using accelerometers and processing circuits. This substitution enables continuous quality assurance during the welding process itself, improving reliability while avoiding the need for separate manual or mechanical inspection systems

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Loss of time

If acceleration data is collected and analyzed during welding, then welding defects can be identified immediately, but data processing time and complexity increase

Engineering Contradiction:
Improvedefect detection timeVSAvoiddata processing complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The system monitors only the critical acceleration parameters necessary for defect detection rather than analyzing all possible welding parameters. By focusing on specific acceleration thresholds and patterns that indicate defects, the system achieves rapid real-time detection without requiring complex comprehensive data analysis

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent establishes predetermined acceleration thresholds and defect criteria before the welding process begins. This preliminary setup allows the processing circuits to immediately compare real-time acceleration data against known good/bad criteria during welding, enabling instant defect identification without requiring complex real-time decision algorithms

Inventive Principle:
Principle #10Preliminary action

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

The system effectively detects welding defects in real-time, improving the quality of welds and reducing production costs by enabling immediate identification and correction of welding issues.

Implementation Method 1

an accelerometer securely attached to the first electrode at a location adjacent to the first electrode. The one or more processing circuits are configured to cause the accelerometer to gather a PGW set of acceleration data of the first electrode during the PGW

Methodology Applied
Scientific EffectAcceleration measurement: Accelerometer

Data Source

PatentEP3774155B1Resistance spot weld head with integrated accelerometer
Publication Date: 2025.05.28 MEDTRONIC INC
  • EP3774155B1 patent drawingFigure 1
  • EP3774155B1 patent drawingFigure 2
  • EP3774155B1 patent drawingFigure 3A~3C

AI summary

Aspects of this disclosure relate to a welding system that is configured to execute opposed, step, and parallel gap resistance spot welds (RSW) and associated methods. The system may be configured to switch bases to switch between an opposed weld configuration, a step weld configuration, and a parallel gap configuration. The system may include an accelerometer that is secured to the weld head adjacent one of the electrodes. The system may use the accelerometer to determine whether or not an RSW was defective. Acceleration data may indicate a defective weld when it includes acceleration data that is outside of a threshold range of acceptable acceleration data.