THE CURVE OF TEMPERATURE DISTRIBUTION AT DIFFERENTIAL HEATING OF BILLETS BEFORE IMPRESSION-FREE BENDING-PROFILING

Abstract

Purpose. The purpose of this paper is to provide background information for the design of special induction heaters for technology of uneven differential heating of billets for controlled impression-free bending-profiling. Design/methodology/approach. The analysis of the main methods of differential heating of metal-forming processes was made. It is proved that impression-free methods of pre-profiling of billets before hot die-forging for projected forming is rationally to combine with their gradient heating that changes the plastic properties of the billet differentially by length. It is hypothesized that the most efficient control of forming at the gradient heating realized when the temperature distribution along the length of the profiled workpiece is corresponds to the distribution of deformation. The 18 main heating options for the obtaining the various semi-finished parts configurations are proposed. Furthermore, it becomes a possible the profiling of the workpiece's sector and increase of the efficiency of the bending-profiling of billets with a ratio of length to diameter more than 5.5. The experimental data were processed by the method of least squares and the functional dependence of the temperature distribution in the form of a quadratic function (like verziera Agnesi) is found. Findings. Experimentally confirmed, that the impression-free profiling of billets by buckling with uneven heating along the length can increase the local linear dimensions of cross-section on 38...45%. According to expressed hypothesis, the shape of the gradient curve of temperature distribution for the intensification of the process of billet profiling by buckling is experimentally obtained by measuring the distribution of bulges along the length of the curved axis of the workpiece. It is determined that the shape of the gradient curve of temperature distribution is independent of the conventional degree of deformation and depends only on the ratio of the height (length) to the diameter intended for the profiling of billet sector. Originality/value. The results are the basis for the design of induction heaters uneven heat for profiling billets by buckling. New methods of profiling are designed to expand the range of forged products.