| 摘要 |
<p>According to the present invention, the method to manufacture a pipe comprises: an overlapped parent metal molding process to mold a strip-shaped parent metal into a pipe-shaped parent metal by overlapping both ends in a longitudinal direction; and a parent metal welding process to push both overlapped ends of the pipe-shaped parent metal for mutually opposite directions placing both ends to face each other, and welding. The parent metal welding process can comprise: a step of parting parent metal to push one end of both overlapped ends of the pipe-shaped parent metal with a first wedge and the other end with a second wedge in mutually opposite directions, parting both ends, and placing both ends to face each other; and a step of welding the parent metal by letting the pipe-shaped parent metal pass through an inside of an induction coil and performing a high-frequency welding of both ends of the pipe-shaped parent metal. According to the present invention, cracks are prevented from being generated as tensile strength is applied as an internal stress on the external side of a pipe as in a conventional technology, which is a crack formed along a metal flow. That is, the present invention prevents a crack from being generated as both ends of a pipe-shaped parent metal are overlapped before welding; the position is changed with both ends overlapping each other and contacting a push means; a compression stress, which is a power to push to the other end not only in an internal side of both ends of the pipe-shaped parent metal but also in the external side, is generated; the welding bead cut; and finally, compression stress also applied as an internal stress on the external side in the manufactured pipe.</p> |
