SMOOTH INNNER SURFACE PIPE USING LOCK-SEAM, MANUFACTURING METHOD THEREOF AND MANUFACTURING APPARATUS

摘要

PURPOSE: An inner flat pipe using a lock seam, a manufacturing device and a manufacturing method thereof are provided to prevent soil contamination by preventing burst caused by internal and external pressure. CONSTITUTION: A manufacturing method of an inner flat pipe using a lock seam is as follows. Overlapped parts are formed in both ends of a steel sheet and are bent in a predetermined shape. A steel pipe(2) is formed by rolling the steel sheet in a spiral shape. A lock seam(6) is formed by pressing the overlapped parts at the rolled part of the steel sheet.