Extrusion head for tubular bodies and hollow profiles

摘要

An extrusion head for producing hollow profiles such as thick-wall large diameter PVC pipe has its flow channel divided by a hollow mandrel into two coaxial portions of a flow cross section greater than that of the common portion of the flow channel downstream of these coaxial portions and running through the mouth of the head. According to the invention, the flow channel progressively diminishes the flow section over the length thereof at least from the plate at which the coaxial portions start to eliminate structural defects caused by failure of the streams of synthetic resin to adequately merge.