Impact of the Different Friction Coefficients on the Tools on the Mechanics of the Mannesmann 2-roll Tube Piercing

Abstract

A numerical parametric study on friction in cross-roll tube piercing is reported in this paper, in order to assess the role of the different friction coefficients on the different parts of the complex tooling of this process (friction on cross-rolls, Diescher disks, piercing plug). Their effects on entrainment speed, state of strain and stress are quantitatively evaluated using the 3D Finite Element Method (FEM). This knowledge allows measures to be taken in case of friction-dependent defects occurring on the piercing mill. Simple regression formulae are proposed which highlight which friction coefficient(s) most impact feed efficiency, twist angle, piercing plug force and torques on the different tools. Based on these relations, a strategy is developed, involving measurements to be performed and equations to be used for an unambiguous friction coefficients identification procedure.