To get the desired wall thickness, the hollow billet enters an "elongator," which is a new set of perpendicular rollers with a specifically-shaped piercer to squeeze it into a longer, thinner tube.
The present invention relates to apparatus for simultaneously shaping the ends of lengths of pipe and severing these lengths from continuous tube being generated by a tube making machine. This tube making machine forms tube of selected diameters in virtually unlimited length by wrapping a ribbon of thermoplastic extrusion around a mandrel or series of mandrels. This extruded ribbon of thermoplastic material includes first and second edges which are abutted one against the other in a spiral in order to form a substantially imperforate pipe. These first and second edges have mating shapes to provide an interlocking function. The ribbon further includes at least one upstanding, radially extending rib which results in the Spiral Tubeformer having greater rigidity or resistance to crushing forces than would a pipe of uniform wall thickness based on equivalent material/unit length.
The hot extruded method is a variation on seamless pipe. Taking the first-stage hollowed billet, manufacturers load it into heating press known as an "extruder" (Figure 2). A long metal bar meant to set the finished pipe diameter (i.e. the "mandrel") runs from the base of the press up through the middle of the billet. The other end of the press is covered with a patterned opening known as a "die," designed to set the outer diameter of the finished pipe. Electrical resistance heats the billet and the powerful hydraulic press pushes the malleable billet up through the die, resulting in a long stretch of steel pipe.