STRAIGHTENING OF LOW-RIGID CYLINDRICAL DETAILS. PART 2. STRESSED STATE OF CYLINDRICAL BILLETS AT TRANSVERSE CHEESING BY FLAT PLATES

Abstract

To restore the shape of curved low-rigid cylindrical details such as shafts and axles, bending straightening under distributed loading is proposed, followed by hardening of the billet using surface plastic deformation based on transverse cheesing of it by flat plates. It is known that after straightening by transverse bending, non-equilibrium stresses are formed over the entire volume of the billet and over time the shape of the detail may again be distorted. Therefore, after performing the straightening process by bending, it is necessary to additionally strengthen the billets by surface plastic deformation based on the transverse cheesing of them by flat plates. The aim of the work was to determine the condition of capture and stress state of the billet during such transverse cheesing. We used the mathematical apparatus and software package Ansys Workbench. The novelty of the work is a new way to manage the stress state when straightening cylindrical billets. As a result, the value of the capture limiting angle α is in the range of 2 – 8°. Maximum value of the absolute reduction depends on friction coefficient and diameter of the billet. Optimal value of the absolute compression is in the range of ΔH = 0.07 − 0.15 mm. The calculation results have shown that after transverse cheesing, in the center of the billet’s cross section there is a stress state of all-round tension, and a stress state of compression is formed in the billet’s shell. The method of hardening by transverse cheesing with flat plates eliminates the cracks formation and material destruction in the central part of cylindrical products.