Apparatus for manufacturing reinforced tubings from plastic materials

Claim 1

An extruder for making strand reinforced tubing comprising: a mouthpiece having an inner wall defining a central bore with an inlet and an outlet end, a guide passing through said central bore to define therewith an annular tube-forming cavity having an entry and exit end, structure defining a first chamber, said first chamber communicating with said inlet end of said mouthpiece bore and containing plastic substance for partially forming said tube in said annular cavity when said plastic substance is input to said annular cavity from said first chamber via said inlet end, initiation of said partial tube formation being at a point intermediate said entry and exit ends of said annular cavity, said mouthpiece having feed channels intersecting said central bore inner wall and which has an output end communicating with said annular cavity at a location both between said entry and exit ends thereof and downstream of said intermediate point whereat said tube initiates formation, feed channels for ribbon- or thread-like reinforcing material, which channels pass through the bore wall into the central bore in two radial planes lying at a distance from one another, the channels of the second plane, observed in direction of transit of the tubing, opening into a section of the bore with an enlarged diameter, strand-like reinforcing material in said feed channel for feeding said reinforcing material onto the outer surface of said partially formed tube and thereby reinforcing it, and structure defining a second chamber, said structure including a disc having a central bore coaxial with said mouthpiece bore for giving said partially formed and reinforced tube an outer contour, said second chamber communicating with said exit end of said tube-forming annular cavity and with said disc bore, said guide also passing through said disc bore.