Extruder for Extruding Pipes

In a pipe extruder, there are two steps in production. The main machine is a conical twin screw extruder. Firstly, a mandrel pierces a hole through the center of a billet, and the tip of the mandrel ends up just within the opening of the extrusion die. Second, the now hollow cylindrical billet is extruded through the die and over and around the tip of the mandrel. The process produces a pipe. To limit the movement of the mandrel, stroke-limiting rods pass through bores in a part attached to the mandrel and in a fixed part of the press. The rods can be held fast in one or both of these bores, or released to slide through them, depending on the stage reached in the extrusion process.