| 摘要 |
PURPOSE:To form a long cylindrical foamd product, keeping its inner diameter at a desired constant value by connecting the inside of a cylindrical body to atmosphere immediately after extruding, when polyolefine family resin is continuously formed with foaming. CONSTITUTION:The composition composed of the polyolefine family resin 1 containing a foaming agent (e.g. the low density polyethylene mixed with dichlorodiffuoromethane) is transferred to the right side from the heating and melting zone 3 of an extruder 2, melting the composition by a screw 4. Further, said composition is sent into the mold 8 in which a cylindrical inner mold 6 is separately provided in the central part of a cylindrical outer mold 5 by means of a fixing bridge 7, and a cylindrical body 11 is formed with foaming, extruding said composition like cylinder from a nozzle 9. Then, the inside of the cylindrical body, immediately after said body passes the nozzle 9, is connected to atmosphere through the gas introducing pipe 10 piercing the outer mold 5 and the inner mold 6 and opening at the tip of the inner mold 6. (or the pressurized air of about 200-300mm. H2O by guage pressure may be also injected). |
