WATER PIPE FOR WHICH HYDROFORMING IS EMPLOYED, AND A PRODUCTION METHOD THEREFOR

摘要

Disclosed are a twin-piping water pipe for which hydroforming is employed, and a production method therefor. According to the present invention, the production method for the twin-piping water pipe for which hydroforming is employed comprises the steps of: (a) inserting, into an outer tube formed from steel, an inner tube which is formed from a corrosion resistant material selected from stainless steel, titanium and aluminium and which has an outer diameter smaller than the inner diameter of the outer tube; (b) stably placing the outer tube in a mould and then sealing the two ends of the mould by using a sealing means having a throughhole connected to a fluid supply device for supplying a fluid to the inner tube; (c) supplying the fluid to the inner tube and thereby plastically expanding the inner tube and resiliently expanding the outer tube; and (d) discharging the fluid from the inner tube and thereby resiliently restoring the outer tube and subjecting the inner tube and the outer tube to friction coupling.