| 摘要 |
The present invention relates to an internal smooth tube having a lock seam formed on the outer circumference of a steel pipe, comprising a lock seam (6), which is formed by forming a steel pipe by rolling into a spiral shape a bent ply section (36) (38), which is bent into a fixed shape on both ends of a steel plate (4) length-wise, and the steel plate (4) having the bent ply section (36) (38) formed thereon, and then pressing the overlapping bent ply section (36) (38) at the boundary of the rolled steel pipe, and to a method and a device for manufacturing same. Therefore, the internal smooth tube having a lock seam formed on the outer circumference of a steel pipe of the present invention is thin and light, enabling easy handling during transport and construction, reduces manufacturing cost, maintains strength sufficient to withhold internal/external pressure, increases the strength of a lock seam connecting section to prevent rupture due to severe internal/external pressure, preventing soil contamination due to leakage, thereby being environmentally friendly, and reduces maintenance and repair cost by enabling smooth flow of fluid by eliminating disruption from wave form. |
