Molding method of thermoplastic resin tube

Abstract

Abstract PURPOSE:To mold a thermoplastic resin tube having a circular projection on the outer surface periphery thereof at a given interval by pushing thermoplastic resin retained at the outlet of a die ring as extruded in a tubular manner with the extrusion speed larger than the withdrawing speed intermittently. CONSTITUTION:A thermoplastic resin is extruded through a space between a die ring 1, provided with an orthogonal notch B on the inner surface entirely to the tip from the point A close to the tip face thereof, and a mandrel 2 to form a resin tube P. The moment the work reaches the point A for providing a circular projection P' on the outer surface of the pipe P in the circumferential direction, a withdrawing machine 3 is decelerated or halted. At the same time, a multisectional outer die 5 provided in contact with the tip face of the die ring 1 is closed and the resin fills the notch B to form a projection P'. With the outer die 5 opened, the withdrawing speed is put back to the normal level to mold the tube P having the projection P'. After cooled from the inside with a cooling jacket on an inside mandrel 6 provided at the tip of the mandrel 2, the pipe is withdrawn ahead with the withdrawing machine 3.

Inventors

• 👤 Shingo Takashima

Bibliographic Details