| 摘要 |
The ridged pipe (14) is extruded around the plain plastic pipe (7). An Independent claim is included for the corresponding plastic pipe. Manufacturing equipment as described, is also claimed separately. Preferred features: The plain plastic pipe passes through the extruder (12). Prior to over-extrusion, the plain plastic pipe is coated with release agent. During extrusion, air (15) is blown between the plastic pipe and plastic material (24) emerging from the extruder head. Following over-extrusion, the composite enters a ridge-molding unit (13). Here, toothed belts (17) mold the extruded plastic to form a ridged pipe (14) surrounding the plain pipe. The toothed belts are connected to a pressure reduction system. This draws the extruded plastic material right into the base (18) of each tooth (19). The plain pipe is fed continuously to the extruder, re-directing it just ahead of entry into the extruder. The product passes to a cutter (20). It continues to a winding drum.
|
