Spot Welding Electrode Dressing via Visual Sensor Measurement
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Solution Overview
Problem
Conventional spot welding systems face reliability issues in determining the quality of the shaping process due to inaccuracies in encoder pulse signals and errors in tip diameter or length measurements, often resulting in poor welds from poorly shaped electrodes.
Innovation Solution
A spot welding system equipped with a visual sensor that captures images of the electrodes before and after the shaping process, measures the distance between the base and tip, calculates the cut amount, and judges whether it falls within a predetermined range, eliminating the need for tentative strikes and improving accuracy despite mechanical disturbances or attachment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If encoder pulse signals are used to measure electrode position, then the measurement process is simple, but the reliability deteriorates due to vibrations and mechanical disturbances
Solution Approach 1:
The patent replaces the mechanical encoder-based measurement system with an optical vision system. The vision sensor captures images of the electrode tip, and image processing algorithms extract position and shape information optically, eliminating the mechanical contact and vibration issues inherent in encoder-based systems.
Solution Approach 2:
The patent introduces an optical field as an intermediary between the electrode and the measurement system. Instead of directly measuring mechanical position through encoders, the system uses light to capture the electrode's visual appearance, providing an indirect but more reliable measurement path that is immune to mechanical disturbances.
2Measurement precision
If laser line sensor is used to measure tip diameter, then the measurement can be performed, but errors occur due to attachment position deviations
Solution Approach 1:
The patent creates a visual copy (image) of the electrode tip using a vision sensor. By capturing the entire electrode tip in an image and analyzing its visual characteristics, the system determines the tip shape and dimensions without physical contact, eliminating errors caused by attachment position deviations that affect laser line sensors.
Solution Approach 2:
The patent transitions from one-dimensional point measurements (laser line sensor) to two-dimensional image-based measurements. The vision sensor captures the electrode tip in a 2D image plane, providing comprehensive shape information and enabling more accurate dimensional analysis that is not affected by single-point positioning errors.
3Ease of operation
If tentative strikes are performed to determine shaping quality, then the assessment can be made, but the process becomes complex and time-consuming
Solution Approach 1:
The patent performs the measurement action before the shaping process is complete. By capturing an image of the electrode tip immediately after shaping (without requiring tentative strikes), the system determines shaping quality in advance, eliminating the need for additional testing operations and reducing overall process time.
Solution Approach 2:
The electrode tip itself provides the measurement information through its visual appearance. The vision sensor captures the tip's shape, size, and characteristics directly from the shaped electrode, allowing the electrode to 'self-report' its quality without requiring external testing through tentative strikes.
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 simplifies the quality determination process, enhances the reliability of shaping process results, and prevents poor welds by accurately assessing the cut amount based on visual data, even under conditions of vibration or positional deviations.
Implementation Method 1
a visual sensor configured to obtain an image of the electrode
Implementation Method 2
the image processing section performs image processing on the obtained image and thereby measures a distance between the base and the tip of the electrode
Data Source
AI summary
A spot welding system including a welding gun with an openable/closable electrode pair; and a dressing determination device determining a quality of a shaping process applied to an electrode of the electrode pair. The dressing determination device includes a visual sensor obtaining an image of the electrode, identifying a base and a tip of the electrode on the image and measuring a distance between the base and the tip on the image, by image processing; a visual sensor control section allowing the visual sensor to measure the distance immediately before and after the shaping process is performed; a cut amount calculation section calculating a difference between the distances measured by the visual sensor immediately before and after the shaping process is performed, as a cut amount of the electrode; and a cut amount judgment section judging whether the calculated cut amount is within a predetermined acceptable range.