An Investigation of the Pilger Process by a Plane Strain Analogue

Abstract

A review of the important papers and patents on the pilger process of hot-rolling seamless tubes shows that there have been divergencies of views as to the most desirable type of roll profile to use, and that there is an incomplete knowledge of the loads and torques involved.

An apparatus to simulate successfully the pilger process under plane strain conditions using lead as the working material, and to measure load, torque, and speed was adapted to a milling machine. The choice of a two-dimensional analogue was made in order to eliminate some of the many variables that occur in practice.

The work has shown how such factors as roll profile, amount of reduction, and feed per blow affect loads and torques, and that under given conditions the parabolic cone is more desirable than the hyperbolic. It is pointed out however that in practice it does not necessarily follow that the cam requiring the least power per blow, or generating the lowest peak load or peak torque, produces the most acceptable tube. A theory has been developed to enable loads and torques to be predicted for the plane strain analogue based on Hill's indentation theory.