| 摘要 |
PROBLEM TO BE SOLVED: To prevent the formation of a fold in the middle of drawn plastic foil by installing flexible rollers having spiral grooves on their outer surfaces and an inversion bar and producing the foil using a molding machine by blow molding. SOLUTION: Tubular plastic foil is moved in the arrow direction in a drawing mechanism. In this process, two flexible rollers 10, 10 and an inversion bar 14 are provided. In the flexible roller 10, spiral grooves 16, 18 are formed on the outer surface. Opposed pitches produced from a parting line 20 which divides the longitudinal length of the flexible roller 10 equally are selected so that the plastic foil extending on the roller 10 is stretched outside, or the generation of a fold in the middle of the foil is prevented effectively. The grooves 16, 18 can be made easily on the rubber surface of the flexible roller 10 by forming recessed parts. |
