In-situ Temperature Measurement using a Multi-sensor Camera during Laser Welding

Yamashita, Shotaro; Yamamoto, Mikio; Shinozaki, Kenji; Kadoi, Kota; Mitsui, Kenji; Usui, Hiroyuki

doi:10.2207/qjjws.33.93s

Cited by 16 publications

(6 citation statements)

References 9 publications

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“…The two-color temperature measurement method has been used in past studies to measure molten steel temperatures [18,19]. In this method, three images in wavelength ranges corre sponding to red (R), green (G) and blue (B) are captured simultaneously by different color sensors equipped in the camera.…”

Section: Droplet Temperature Measurement Through Two-color Temperatur...mentioning

confidence: 99%

Study on factors affecting the droplet temperature in plasma MIG welding process

Mamat

Tashiro

Tanaka

et al. 2018

J. Phys. D: Appl. Phys.

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In the present study, the mechanism to control droplet temperature in the plasma MIG welding was discussed based on the measurements of the droplet temperature for a wide range of MIG currents with different plasma electrode diameters. The measurements of the droplet temperatures were conducted using a two color temperature measurement method. The droplet temperatures in the plasma MIG welding were then compared with those in the conventional MIG welding. As a result, the droplet temperature in the plasma MIG welding was found to be reduced in comparison with the conventional MIG welding under the same MIG current. Especially when the small plasma electrode diameter was used, the decrease in the droplet temperature reached maximally 500 K. Also, for a particular WFS, the droplet temperatures in the plasma MIG welding were lower than those in the conventional MIG welding. It is suggested that the use of plasma contributes to reducing the local heat input into the base metal by the droplet. The presence of the plasma surrounding the wire is considered to increase the electron density in its vicinity, resulting in the arc attachment expanding upwards along the wire surface to disperse the MIG current. This dispersion of MIG current causes a decrease in current density on the droplet surface, lowering the droplet temperature. Furthermore, dispersed MIG current also weakens the electromagnetic pinch force acting on the neck of the wire above the droplet. This leads to a larger droplet diameter with increased surface area through lower frequency of droplet detachment to decrease the MIG current density on the droplet surface, as compared to the conventional MIG welding at the same MIG current. Thus, the lower droplet temperature is caused by the reduction of heat flux into the droplet. Consequently, the mechanism to control droplet temperature in the plasma MIG welding was clarified.

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Section: Droplet Temperature Measurement Through Two-color Temperatur...mentioning

confidence: 99%

Study on factors affecting the droplet temperature in plasma MIG welding process

Mamat

Tashiro

Tanaka

et al. 2018

J. Phys. D: Appl. Phys.

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“…Compared with the two-color pyrometry, it has a higher temperature measurement accuracy but a narrower dynamic range. Yamashita et al [17] developed a temperature measurement technology in the welding process, which used a multi-sensor camera based on the two-color thermometry method. The camera can use three filters to set different spectral wavelengths, to more accurately and quickly respond to the welding temperature in a wide temperature range.…”

Section: Introductionmentioning

confidence: 99%

Temperature Measurement Method of Flame Image Fusion with Different Exposures

et al. 2020

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Fixed exposure will lead to underexposure or overexposure of collected flame radiation images using CCD, which has a great influence on the temperature measuring accuracy. A temperature measurement method was proposed by image fusion with multi-exposure, which can eliminate the influence of insufficient underexposure and overexposure. The approach was first to acquire a group of flame radiation images during different exposures. Then a partial region with good exposure effect in each radiation image was obtained by segmentation, with which the complete flame image can be spliced together. An experimental system was built to calibrate the temperature measurement parameters by two-color pyrometry through a blackbody furnace. The relation between exposure time and monochromatic gray level, as well as the relation between the temperature and temperature measurement coefficient were obtained. A candle flame was selected as the measuring object and the complete and accurate flame temperature distribution was acquired following our proposed method. The experimental results show that, compared with the temperature measurement using a single exposure time, our method can effectively avoid the measurement error caused by underexposure and overexposure, and improve the measurement accuracy.

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“…A detail description of the measurement principle and method have been reported elsewhere by the authors. 8) Figure 2 shows the experiment setup of the 2D temperature measurement using the multi-sensor camera, which is vertically fixed to the specimen to capture the molten pool shape and measure the 2D temperature distribution. The welding condition is same as that of the laser Trans-Varestraint test but without any applied augmented strain during the temperature measurement.…”

Section: Two-dimensional Temperature Measurement Usingmentioning

confidence: 99%

Evaluation of Solidification Cracking Susceptibility for Austenitic Stainless Steel during Laser Trans-Varestraint Test Using Two-dimensional Temperature Measurement

et al. 2016

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Laser beam welding at high speeds enhances solidification cracking susceptibility, and brittleness temperature range must be measured under a high cooling rate to quantitatively evaluate the influence of welding speed upon the susceptibility. This work investigated the influence of welding speed upon the solidification cracking susceptibility of type 310S stainless steel using the laser Trans-Varestraint test. A multi-sensor camera based on two-color thermometry measured two-dimensional temperature distribution around the molten pool to obtain the temperature range along different solidification crack directions, and the applicability and accuracy of the two-dimensional temperature distribution technique for measuring temperature range of cracks was investigated. The brittleness temperature range was measured precisely with this method; it was nearly constant around 102°C at welding speeds from 0.2 to 2.0 m/min. The results demonstrated the effect of the welding speed from 0.2 to 2.0 m/min upon the solidification cracking susceptibility was very small.

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In-situ Temperature Measurement using a Multi-sensor Camera during Laser Welding

Cited by 16 publications

References 9 publications

Study on factors affecting the droplet temperature in plasma MIG welding process

Study on factors affecting the droplet temperature in plasma MIG welding process

Temperature Measurement Method of Flame Image Fusion with Different Exposures

Evaluation of Solidification Cracking Susceptibility for Austenitic Stainless Steel during Laser Trans-Varestraint Test Using Two-dimensional Temperature Measurement

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