subject: pipe extrusion line [print this page] pipe extrusion line pipe extrusion line
There is provided a pipe extrusion line that includes a first and second die assembly. The first and second die assembly each include an extrusion head, a nozzle carrying an outer die lip, a hollow mandrel, an inner mandrel carrying an inner die lip, and a layer-forming channel. The layer-forming channel is defined by the space between the nozzle and inner mandrel. The extrusion die includes a space between the nozzle of the second die assembly and the inner mandrel of the first die assembly such that the first and second die assembly do not share a common wall. The space between the inner and outer die lip (die gap) can be individually adjusted and the second die assembly is freely movable relative to the first die assembly. The pipe extrusion line also includes a vacuum cooling mandrel with a single cooling channel and multiple vacuum ports that provide improved vacuum control over the final die product.
According to one aspect of the invention, therefore, there is provided an extrusion line for use in an apparatus to produce multi-layered pipes, the extrusion die comprising: (a) a first and second die assembly, each die assembly comprising: (i) an extrusion head having a central bore and a lateral opening for receiving an extrudate; (ii) a nozzle, operably connected to the extrusion head, the nozzle having an outer die lip at a free end of the nozzle; (iii) a hollow mandrel coaxially located in the central bore, (iv) an inner mandrel coaxially located in the hollow mandrel and in the nozzle, the inner mandrel having an inner die lip at a free end of the inner mandrel; the inner die lip and outer die lip defining a die gap; and, (v) the nozzle and inner mandrel defining a layer-forming channel in fluid communication with the lateral opening and the die gap; wherein a central portion of the nozzle of the second die assembly is co-axially located within the inner mandrel of the first die assembly such that the nozzle of the second die assembly and the inner mandrel of the first die assembly define an air space.
According to another aspect of the invention, there is provided an extrusion die for use in an apparatus to produce multi-layered pipes, the extrusion die comprising: (a) a first and second die assembly, each die assembly comprising: (i) an extrusion head having a central bore and a lateral opening for receiving an extrudate; (ii) a nozzle operably connected to the extrusion head, the nozzle having an outer die lip at a free end of the nozzle; (iii) a hollow mandrel coaxially located in the central bore; (iv) an inner mandrel coaxially located in the hollow mandrel and in the nozzle, the inner mandrel having an inner die lip at a free end of the inner mandrel; the inner and outer die lips defining a die gap; and, (v) the nozzle and inner mandrel defining a layer-forming channel in fluid communication with the lateral opening and the die gap; wherein a central portion of the nozzle of the second die assembly is co-axially located within the inner mandrel of the first die assembly.
