Pilger Mill Rolls.
In the cold pilger process, thick walled seamless tubes (hollow blooms) are finished to the required final size. The roll stand consists of two rolls that turn in reverse to the rolling direction. The roll profi le steadily reduces, in a taper, to the finished tube diameter. The tube is rolled over an internally located conical mandrel. It is essential that during the rolling of the hollow bloom down to the finished tube, a stretching of the diameter as well as a reduction of the wall thickness occurs. The process repeats itself cyclically until the entire tube has been finish formed. Depending of the type of mill, reduction is carried out using either a roll die jaw or a ring roll. Due to its higher production output and more favourable deformation ratios, long stroke pilger mills, utilising ring rolls, are mainly used today.