Patent ID: 7037098
Filing Date: 2006-05-02
Classification: B29C

Abstract:
1. Apparatus for producing seamless plastic tubes, comprising at least one extrusion device, at least one injection head connected downstream of the extrusion device in the production direction, with at least one annular gap which is preferably in the form of a circular ring, and at least one mould cavity which is connected downstream of the injection head in the production direction and which is formed for example by travelling corrugator jaws and which is coaxial with the annular gap, for shaping the plastic tube from at least one flow of molten plastic material which issues from the annular gap of the injection head, wherein it is provided that the injection head has a plate-shaped distribution device which is arranged within the cross-section of the mould cavity and which has an intake opening into which a feed passage for the molten plastic material opens, wherein the distribution device has a plurality of distribution passages which extend in a star configuration from the intake opening and which extend substantially perpendicularly to the axis of the mould cavity and/or the annular gap, wherein each distribution passage has a straight, radial passage portion which extends from the intake location and preferably branch passages which extend from a branch location at the end of the radial passage portion, wherein a total of n ends of the distribution passages open in the region of the periphery of the distribution device into the annular gap at a respectively identical angular spacing between adjacent ends at an angle of 360°/n, forming n flow paths which each extend from the intake opening in mutually adjoining passage portions of the distribution passages to open into the annular gap and introduce respectively equal volume flows into the annular gap, characterised in that at least two of the flow paths are of different lengths and to ensure that an equal volume flow is introduced into the annular gap (