| 摘要 |
<p>A polymer resin extrusion head includes one or more annular extrusion modules in which a spiral channel means having one or more convolutions extends from a resin inlet on the periphery of the module to an annular extrusion outlet. Preferably, the channel means gradually opens into an annular frustoconical space leading to the extrusion outlet at the inner edge of the module. The spiral channel extends symmetrically around the extrusion module or modules in a manner so as to subject all of the extruded polymer flowing from the inlet to the extrusion outlet to substantially the same process conditions along the flow path. As a result, the polymer is distributed at the outlet with properties which are substantially symmetrical around the axis of the extrusion module or modules for all resin distributed to the outlet. It is preferable that the extrusion module or modules comprise a pair of mating annular members with central frustoconical portions having apexes with an axial dimension greater than the axial dimension of the outer portions of the modules so as to form air spaces around each module including frustoconical air space portions to avoid direct heat transfer between adjacent modules.</p> |
