Resistance Welding Temperature Estimation Using Electrode Displacement
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Solution Overview
Problem
Existing resistance welding methods face challenges in accurately estimating the temperature of the welding portion during mass production, particularly due to rapid changes in contact resistance and physical phenomena at the initial stage of welding, which complicates the calculation of time-series temperature distribution and is hindered by factors like dust generation.
Innovation Solution
A resistance welding control system that includes an electrode displacement detector and a temperature estimation unit, which acquires voltage, current density, and physical property data to estimate the welding portion's temperature, stabilizing electrode displacement and voltage to facilitate accurate temperature calculation using a heat conduction model, reducing the need for precise initial calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature estimation is performed from the start of welding using heat conduction model, then welding quality can be monitored, but calculation accuracy deteriorates due to rapid changes in contact resistance and physical phenomena at initial stage
Solution Approach 1:
The patent applies preliminary action by performing preliminary welding operations (approach phase) before the actual welding measurement phase. During this approach phase, the electrode displacement is controlled to be within a predetermined range, allowing the system to establish stable initial conditions and obtain accurate physical property values before temperature estimation begins, thus avoiding the unreliable initial stage data
Solution Approach 2:
The welding process is segmented into distinct phases: an approach phase for establishing stable conditions and a measurement phase for temperature estimation. This segmentation allows the system to separate the unreliable initial welding stage from the accurate measurement stage, improving overall estimation accuracy by only using data from the stable measurement phase
2Measurement precision
If detailed time-series temperature distribution calculation is performed, then welding quality can be accurately assessed, but calculation load increases significantly
Solution Approach 1:
The patent extracts only the essential parameters needed for welding quality assessment (electrode displacement, physical property values, and temperature at critical points) rather than calculating the complete time-series temperature distribution. This extraction approach maintains sufficient assessment accuracy while dramatically reducing calculation complexity and computational load
3Productivity
If welding measurement is performed in mass production conditions, then productivity is maintained, but measurement accuracy deteriorates due to dust generation and rapid physical changes
Solution Approach 1:
The patent applies the skipping principle by rapidly transitioning through the approach phase to reach the stable measurement phase, minimizing the time spent in conditions that generate dust and rapid physical changes. This allows mass production efficiency to be maintained while ensuring measurements are taken only during the stable, clean measurement phase
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 allows for enhanced welding quality by accurately estimating the welding portion's temperature, ensuring the welding strength exceeds the melting point, even in mass production scenarios, with a reduced calculation load and minimized dust interference.
Implementation Method 1
an electrode displacement detector configured to detect a positional displacement between opposite electrodes
Implementation Method 2
estimating a temperature of a welding portion between the welding members on the basis of the temperature estimation information and the positional displacement between the opposite electrodes
Implementation Method 3
Known resistance welding, which is so-called spot welding, is achieved by melting welding members by Joule heat generated by a contact resistance between the welding members
Data Source
AI summary
A resistance welding control system includes an electrode displacement detector, a temperature estimation information acquiring unit, and a temperature estimation unit. The electrode displacement detector detects a positional displacement between opposite electrodes while the electrodes are supplying electricity between the electrodes to perform resistance welding of welding members held between the electrodes. At least one of the electrodes is movable toward or apart from the other electrode. The temperature estimation information acquiring unit acquires at least an interelectrode voltage, a current density in the welding members, and a physical property value of the welding members as temperature estimation information to be used to estimate a temperature of a welding portion between the welding members. The temperature estimation unit estimates the temperature of the welding portion based on the temperature estimation information and the positional displacement while at least either one of the positional displacement and the interelectrode voltage is stabilized.