| 摘要 |
In a conventional multilayer crosshead, only one pressure sensor is disposed in the inlet of the annular passage, preventing monitoring of membrane discontinuities; parison thickness is not constant; as the crosshead body is not cooled and parison temperature is high, a long time is required for cooling during blow molding, preventing the reduction of the molding cycle. A multilayer crosshead according to the present invention includes pressure sensors disposed in at least two positions of the annular passage so that the flow rate is controlled and monitored so as to eliminate the pressure difference between the pressure sensors, and parison temperature is lowered to a greater degree by a cooling jacket with a built-in heater disposed in the crosshead body so that a blow molding cycle is shortened.
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