| Project/Area Number |
12650725
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Nagaoka National College of Technology |
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Principal Investigator |
NAKAMURA Susumu NAGAOKA COLLEGE OF TECHNOLOGY DEPARTMENT OF ELECTRONICAL ENGINEERING, ASSOCIATE PROFESSOR, 電気工学科, 助教授 (10217854)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | YAG LASER / WELDING / MONITORING / OPTICAL EMISSION / ACOUSTIC EMISSION / 周波数解析 |
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| Research Abstract |
In this study, we propose a technique to detect the welding characteristics between deep penetration mode and shallow penetration mode in CW 4kW YAG laser welding. The optical and acoustic emissions during bead-on plate welding and butt welding were measured for mild steel SS400, stainless steel SUS304 and aluminum alloy A5083. A frequency analysis of these emissions was performed up to 40 kHz. When the welding characteristics changed from deep penetration mode to shallow penetration mode in mild steel during bead-on plate welding, main frequency components of the acoustic spectrum shifted from lower frequency range to higher frequency range according to the decrease in the penetration depth. The similar shift of the main frequency components was observed for the optical spectrum.
This phenomenon was observed independent of kinds of material and also observed during butt welding.
In order to make clearer these changes in frequency spectra, ratio of the emission intensities in two characteristics frequency ranges was correlated to aspect ratio of the welding bead. As a result, we found that the intensity ratio of low frequency components versus higher frequency components of the spectra correlated well to the aspect ratio. For example, the intensity ratio of the optical emission of 23-25 kHz to 2-4 kHz showed a good correlation with the aspect ratio during bead-on plate welding, and the intensity ratio of the acoustic emission of 32-35 kHz to 2-4 kHz correlated well to that. Thus we could evaluate whether the welding was deep penetration mode or shallow penetration mode by analyzing the frequency components of the emission signals. The deference of the frequency spectrum may be useful in the development of a feedback system for control of weld quality.
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