| 摘要 |
PURPOSE:To enhance a productivity and improve a surface appearance by a method wherein before a melt parison us clamped between molds, the outer surface of the melt parison is depressed by a sizing former. CONSTITUTION:A melt parison (e) extruded from a die (a) is passed through a sizing former (b) before the surface of the melt parison (e) is cooled and set. At this time, the inner surface of the sizing former (b) is brought into pressure contact with the surface of the melt parison (e), whereby a die line, a melt fracture, a spot, and the like are eliminated. The sizing former is depressed on the melt parison so that the melt parison cannot be deformed to a great extent by the frictional resistance between the melt parison and the sizing former at the time of molding and so that the both cannot be fused to each other. It is effective that the sizing former is mounted at a position 10-100mm lower than the lower end of the die (a). It is effective that the depressing part of the sizing former on the melt parison (e) has a length in a range of 1-80mm. |
