To reduce cost in a thickness adjustment device for parison for changing the thickness only at a longitudinal position and circumferential position of an optional prison.
The thickness adjustment device 1 includes: a core 2 having a first inclined surface 6 around the lower end thereof; a die 3 disposed outside the core 2 and having a second inclined surface 7 facing the first inclined surface 6 around the lower end thereof; and a parison annular inclined flow passage 8 and a parison ejection port 9 formed between the first inclined surface 6 and the second inclined surface 7. The device changes the vertical thickness of a parison by relatively moving the core 2 and the die 3 in the vertical direction. A straight flow passage 10 is provided at a part in the circumferential direction of the annular inclined flow passage 8 extending to the parison ejection port 9 so as to extend in parallel to the relative movement direction of the core 2 and the die 3.
SAKAMOTO SHINICHI
WADA NAOHIRO
Etsuo Tada