Method to produce plastic tube

A method to produce a plastic tube, according to which method a material of the plastic tube is fed upon a core that is equal in size as an inside diameter of the plastic tube, the material of the plastic tube being fed as an uninterrupted material flow so that the material flow advances after having come upon the core essentially following a helical line, wherein

• the core is a tube that rotates during the production process around a central axis,
• upon the core there is an essentially cylindrical and concentric mold, a first end of the mold comprising a stationary end plate that includes a portion angled in the direction of the advance of material flow upon the core directing the material flow to move in a direction along the axis of the core toward an other end of the mold during rotation of the core, wherein the other end of the mold includes an end plate having an edge portion that defines an opening between the edge portion and the core, the opening configured to define a wall thickness of the plastic tube being produced over an outside diameter of the core,
• wherein the material flow consists of at least one solid material ribbon and a melted plastic material,
• each material ribbon advances upon the core following the helical line to form material ribbon rounds upon the core, wherein a gap is defined between adjacent material ribbon round, the gap having a width that corresponds to an extent of the inwardly angled portion of the stationary plate on the first end of the mold,
• the melted plastic material fills the gaps between adjacent material ribbon rounds and other gaps between the material ribbon rounds, where the adjacent layers of material ribbon rounds are welded together along a welding joint,
• an end of the plastic tube is pressed and fixed by welding to an end of a starting tube, the starting tube being a continuation of the core, concentric and rotating with the same speed, and
• wherein the starting tube and the plastic tube that is fixed to it are moved in the direction of the central axis with the same speed as the plastic tube is produced in the mold.