| 摘要 |
PURPOSE: To prevent generation of welding defect by executing welding of a fixed tube for a first layer, build-up layer, final layer with use of root gap, welding condition values in which data base is established beforehand. CONSTITUTION: A narrow gap 3 is formed at the end part of fixed tubes 1, 2, the root part of gap 3a is made to V shape havingθof 90-150 deg.. A copper backing metal is abutted on the rear face of gap, first layer welding is done with use of the high rotary arc welding method of 20-100Hz arc rotating speed and 1-4mm arc rotating diameter. Welding torch height control and narrow gap copying control are executed by an arc sensor while sensing the arc electric current and voltage waveform. Peripheral downward welding is executed while welding condition is selected from the optimum welding condition database. Build-up welding is executed while welding condition is select from the optimum welding condition database. By weaving welding torch in final layer welding, peripheral downward welding is executed while welding condition is selected from the optimum welding condition database. By this method, the welding having reduced deposited metal quantity is executed in high efficiency.
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