To provide a method for welding a metallic pipe, which can solve problems of a method for welding metallic pipes using a squeeze roll, and can set a so-called V-shape angle in the vicinity of a welding point large, and can accurately constrain and press the cross section of the pipe, and can efficiently manufacture a straight seam welded pipe having high welding quality.
Because the cross section of the pipe is continuously constrained and pressed during welding or just after welding along the longitudinal direction using dies instead of a squeeze roll, effects of variation of welding points, etc., upon welding results are reduced, and the spring-back behavior of the pipe after the welding point can be effectively suppressed, and the percentage of occurrences of welding defects can be remarkably reduced, and the productivity can be improved. Further, the friction between the dies and the pipe can be remarkably reduced by forming surface traveling waves by transferring the vibration to the surface of the dies by applying the ultrasonic vibration to the dies.
ABE FUSAJI
O HISHU
NAKANO TOMOYASU
Yoshiteru Oshida
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