| 摘要 |
PURPOSE: A multi-layer pipe using hydroforming and a manufacturing method thereof without an additional adhesive are provided to smoothly discharge air and impurity from the interval of an internal steel pipe and an outer steel pipe. CONSTITUTION: A mold equipped with an outer steel pipe, an inner steel pipe, and a molding groove is prepared(S-11). The inner steel pipe has the external diameter corresponding to 95-98% of the inside diameter of the outer steel pipe. The molding groove has the diameter corresponding to 100.20-100.30% of the external diameter of the outer steel pipe. A discharge hole is formed on the outer steel pipe(S-12). The central axis of the inner steel pipe and the central axis of the outer steel pipe are in arranged to settle the mold on the molding groove(S-13). The outer steel pipe adheres closely to the molding groove(S-14). |
