| 摘要 |
PURPOSE:To produce readily and inexpensively a pipe excellent in the heat insulating properties, by blowing a foamable resin onto the inner and outer surfaces of a pipe being vertically held, and blowing a hot air flow upon the foamable resin to foam it. CONSTITUTION:Thin pipes (C) each having a hot air blow-off hole 1 and a foamable resin blow-off hole 2 are arranged inside and outside of the vertically held pipe (A). Then while the pipe (A) is being rotated, and the thin pipes (C) are being moved axially, the foamable resin is blown off through the blow-off holes 2 to form resin layers respectively on the inner and outer surfaces of the pipe (A), and currents of hot air are driven via the holes 1 upon the resin layers to foam them. Thus, the pipe improved in the heat insulating properties by forming the foamed plastic layers respectively on the inner and outer surfaces can be readily and inexpensively obtained. |
