| 摘要 |
PROBLEM TO BE SOLVED: To form the boundary part between a pipe main body and an annular rib protruded part into an obtuse angle with a shoulder regardless of the extrusion direction by molding the annular rib by feeding a molten synthetic resin into a corresponding cavity and exhausting remaining air in the cavity from an air vent. SOLUTION: After a molding apparatus is arranged on an extruder in tandem, a molten parison P of, e.g. polyvinyl chloride resin extruded from the extruder is introduced between a closed space formed by rotating two pairs of endless sprue-shaped connected metal groups M in the arrow mark direction and bonding them and a mandrel 4. Then, while the parison P is moved in the closed space, molding is performed while the remaining air in the mold piece (m) is exhausted from an air vent to obtain a synthetic resin pipe with a rib. An obtuse angle with a shoulder is formed on the boundary part between the pipe main body and the annular rib protruded part of the obtd. synthetic resin pipe with the rib. It is pref. that this air vent is provided at a position corresponding to the boundary part of the pipe main body and the annular rib protruded part. |
