1991 Fiscal Year Final Research Report Summary
Study on Stabilization of Welding Arc under Hyperbaric Condition
| Project/Area Number |
02650532
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
溶接工学
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| Research Institution | Keio University |
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Principal Investigator |
SUGA Yasuo Keio University, Faculty of Science and Technology Associate Professor, 理工学部, 助教授 (60051900)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Welding / High pressure / Stabilization of arc / Magnetic field / Erosion of electrode / La203-tungsten electrode / Hyperbaric welding |
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| Research Abstract |
In hyperbaric TIG arc welding, the arc tends to be unstable and accordingly it is difficult to obtain sound welds. Therefore the effects of magnetic field and the frequency of alternating magnetic field on the arc phenomena and welding results were investigated.
Main results obtained are summarized as follows : 1)Applying magnetic field to a welding arc under high pressure, the constriction of the arc is released and its diameter increases.
2)Applying static field to an arc under high pressure, irregular fluctuation of arc voltage is prevented, but the arc voltage vibrates in a period of 0.5ms approximately. Accordingly, the arc may turn or vibrate in a frequency of 2 kHz.
3)Applying alternating magnetic field to an arc under high pressure, fluctuation of arc voltage is prevented, but the arc voltage vibrates depending on a frequency of excitation current.
4)Applying alternating magnetic field to an arc under high pressure, straight and sound welds can be obtained by a relatively stable arc. However, effect of frequency of magnetic field on welding result is not observed.
5)In a higher frequency of magnetic field, a higher excitation current must be used in order to obtain a same magnetic flux density in a lower frequency. As the result, the excitation coil has a tendency to be heated in operation.
6)The erosion of La2O3-W electrode is much less than that of ThO2-W electrode. At the tip of the La2O3-W electrode during welding, La2O3 exists at the surface and it makes the work function decrease and prevents superheat of the electrode tip. As the result, erosion of the electrode may become smaller than those of other electrodes.
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