VIBRATION PIERCING OF PIPE BILLET ON THE PIERCING PRESS OF PIPE-ROLLING MILL

Abstract

The issues of using highly efficient technologies in the production of pipes on the piercing press of a pipe press installation are considered. The existing basic and perspective directions of intensification of deformation modes in the processes of metal forming using active controlled high-frequency vibrations are analyzed. It was established that, due to insufficient study, vibration processes do not find wide application in the production of seamless pipes. By analyzing and synthesizing a number of known fundamental studies, it has been shown that favorable conditions for metal deformation can be achieved by using high-frequency vibrations. It was revealed that the operation of the pipe billet piercing on the piercing press is accompanied by considerable losses to overcome the forces of technological resistance, characteristic for the process of deformations unevenness throughout the volume of the processed metal. Some previously unknown phenomena that arise during the implementation of existing technologies for pipe billets piercing have been established, which required the creation of new mathematical models of such processes that adequately reflect the conditions of the process of piercing or expanding the billets on modern piercing presses. A mathematical model of the dynamic wave processes arising in the processed metal is made. For the quasistationary process of pipe billet piercing differential equations of wave formation are obtained at the corresponding boundaries of the zones of the deformation center, characteristic for the plastic zone and the zone with cracking in the pierced metal. The parameters of the wave propagation boundary in the pierced pipe billet on the conjugate fronts of the plastic zone with the zone of crack formation are determined. It was established that deformations and stresses in the pierced metal depend on the rate of expansion of characteristic waves at the interface of contact with technological tools. A highly effective innovative technology of vibration piercing of a pipe billet on a piercing press of a pipe-rolling mill is substantiated. The features of realizing the technology of active controlled vibration piercing of the pipe billet on the piercing press of a pipe-rolling mill are determined. It is shown that the use of high-frequency oscillations on the press contributes to a significant increase in the efficiency of the technological process of piercing or expansion of pipe billets. The choice of rational parameters of high-frequency vibrators (amplitude-frequency characteristics), built into the system, resulted in a noticeable decrease in the energy-strength parameters du­ ring the piercing of the pipe billet and a significant improvement in the quality of the produced sleeves.