| 摘要 |
PROBLEM TO BE SOLVED: To provide a butt welding method which forms penetration bead stably without special welding method or high degree method for controlling welding conditions, is able to weld by single pass even for thick plate members. SOLUTION: The butt welding method which comprises a preceding welding torch 10 having a tip portion curved almost along to the surface of plate of a welded member 6, a following welding torch 20 having an inclined tip portion mounted with a sealed gas nozzle 23. The under backing plate 9 for preventing molten metal from falling down below the under surface of a groove in a welded member 6, and the upper backing plate 14 having a hole 16 to blow off sealed gas on the upper surface of the groove, the under and upper backing plates arranged so as to move slidably together according to the proceeding of welding, the tip portion of the preceding welding torch 10 inserted into the groove 7 surrounded with the under backing plate 9 and the upper backing plate 14, the following welding torch 20 disposed so as to weld on the top of the preceding welding bead 4 at the backside of the upper backing plate 14, this two welding torches 10, 20 carry out welding simultaneously.
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