Patent ID: 6019934
Filing Date: 2000-02-01
Classification: B29C

Abstract:
A process of producing large-bore thick-walled polyethylene pipes comprising the steps of:extruding polyethylene melt from an annular extrusion die to form a pipe,cooling the pipe emerging from the die by applying water to the inside and outside thereof,placing spaced apart first and second floating plugs inside the pipe for holding water in the space between the plugs, the external diameter of each floating plug corresponding to the internal diameter of the pipe being produced, fixing each of the floating plugs to the annular extrusion die by retaining elements, locating the first floating plug close to the extrusion die and locating the second floating plug a greater distance from the extrusion die close to the where pipe is cut to length, and equipping the second floating plug with quick bayonet closures for supplying and discharging cooling water into and away from the interior of the pipe being produced,providing a plurality of sets of water supply and discharge lines for said supplying and discharging of said cooling water, anddetaching and replacing an active set of supply and discharge lines by a subsequent set of said supply and discharge lines in each case after a pipe section has been cut to length.