| 摘要 |
PURPOSE:To facilitate extraction while assuredly reducing friction, by blow-elongating a plastic material while interposing liquid incompatible with the plastics between the inside surface of an extrusion-blowing metal mold and the outside surface of a plastic cylindrical part. CONSTITUTION:A metal mold 17, whose partial section removing a core shaft 7 and an air sealer 11 is illustrated in the drawing, is provided with a plurality of openings 18 at the upperside periphery of its diameter-expanded part. An opening hole 18a is formed in each opening 18 and communicated to a communicating hole 19 formed inside the thick part of the metal mold 17 in a manner such that the hole 19 surrounds an inside surface 10 of the molding. Incompatible liquid is introduced from a hose 20 into the opening. On the other hand, the same number of suction openings 21 as that of the openings are formed in the in side surface of the metal mold 17 at its open side, communicated through opening holes 21a to vacuum chambers formed in the same way as the communicating holes 19 are, and connected to a sucking hose 23. As the incompatible liquid is used silicone oil, water, alcohol or ketone. |
