| 摘要 |
PURPOSE:To control the thickness of a parison by providing a slice lip at an annular parison extruding slit formed by a mandrel and a nozzle, and projecting this slice lip into the slit. CONSTITUTION:A resin 3 pressed between the mandrel 1 and a head body 2 is extruded as a parison 4 through a slit S formed at the lower ends of the mandrel 1 and the nozzle 5. Upon this occasion, a cylinder 11 is elongated and operated, and a slice slip 7 is advanced to project the tip end of the slide lip 7 into the inner part of the above slit S, and to change this portion so that the slit interval of this portion is narrowed as shown by S2 as compared with the slit interval S1 at the other portion, whereby the thickness of the parison 4 can be made thinner as t2, while the thickness of the other portion is t1. By this controlling method, molded articles having asymmetric thickness, such as gasoline tanks for automobiles, solar heat collectors and the like, can be easily obtained. |
