US 6,547,551 B2 · Multilayer crosshead

Abstract

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.

Claims13

Dependent claims

A multilayer crosshead comprising:

a plurality of extruders for extruding plural different materials respectively;
a crosshead body having a plurality of annular passages formed therein;
and
a die disposed in a bottom portion of said crosshead body including a die slit having a die discharge outlet and being connected to each of said annular passages;
wherein plural materials extruded by said plurality of extruders are supplied to said plurality of annular passages so as to flow from the die slit, said multilayer crosshead further comprising pressure sensors disposed in both an inflow inlet of said annular passage and in a weld portion opposing the inflow inlet in each of said annular passages respectively, and wherein said pressure sensors detect pressure differences between said pressure sensors disposed in each of said respective annular passages.

2 more elements

Dependencies are inferred from the claim text.

Multilayer crosshead

Life of this patent

Multilayer crosshead

Life of this patent

Abstract

Claims13