Cold pilgering is a longitudinal cold-rolling process that reduces the diameter and wall thickness of metal tube in one process step. Depending on the material, the cold pilger process achieves cross-section reductions of more than 90 percent in a single working cycle.

The rolling tools in the cold pilger process comprise a pair of ring dies and a mandrel. The mandrel is located inside the tube in a fixed position and rotated by the mandrel thrust block. The mandrel itself is tapered in the rolling direction. The dies have matching grooves on their circumferences.

A connecting rod drives the mill saddle back and forth. This action causes the ring dies to rotate. This action is similar to a crankshaft driving a piston in an automobile engine. Pinions mounted on each roll shaft engage two racks that are fixed to the machine housing. This arrangement uses the mill saddle’s oscillating motion to generate the ring dies’ oscillating rotary motion.

In the dead-center positions of the mill saddle, the dies briefly disengage the tube. During these end-of-stroke periods, the hollow advances and rotates. Both the forward and return strokes form the tube.

Depending on the groove design, the forming process requires more than 10 steps, feeding and rotating the tube to different positions in relation to the forming die pass. A large number of small forming steps helps to ensure a constant wall thickness and nearly homogeneous material characteristics in the rolled tube.

For more information see the below link

https://www.thefabricator.com/article/tubepipeproduction/introducing-cold-pilger-mill-technology