KINEMATIC ELEMENT MODELING OF HORIZONTAL 2-ROLL PIERCING

A reliable mechanical model is developed in the two-dimensional kinema tic element framework to analyse the influence of setting-mill conditi ons on the stress, strain rate, strain and final seamless-tube outer d iameter. The billet velocity is split into a rotational rigid part and a translational viscoplastic part. The stationary flow region is disc retized into five kinematic elements for the viscoplastic velocity fie ld part, the boundary of elements being dependent on the roll-setting conditions, plug geometry and incipient central cavity dimensions. Vis coplastic material behaviour is introduced in the constitutive equatio ns of the viscoplastic flow. The contact and friction conditions are d escribed by a sub-layer friction model which depends on the bulk mater ial flow stress and on the sliding interface velocity. The related com putation routines are able to run on any personal computer working in the DOS environment and most results are obtained in quasi real-time w ith the usual hardware configurations. Predictions of final outer diam eter are found to be well related to industrial results for a horizont al two-roll piercing mill.