| 摘要 |
PURPOSE:To obtain a covered conduit drainage pipe having high strength of pressure resistance by a method wherein pressure air is supplied to a delivery port, through which a strand of reticulated cylindrical tube is extruded, to form hollow strand. CONSTITUTION:A column type block 7 and a tubular block 10 effect relative rotating motion by transmitting a rotating power to the column type block 7 and transmitting a reverse rotating power to a sprocket 33 whereby molten synthetic resin is extruded from the delivery port 22 through a flow path 14 and a delivery groove 16 while pressure air is forced into respective air flow paths 35-38 whereby the covered conduit drainage pipe P, in which inside solid large strand 47 and the outside hollow large strand 48 are welded integrally by fusion in addition to the screen of fine strands 45, 46,......, may be obtained. |
