DOI: 10.52150/2522-9117-2020-34-90-100

Yeliseyev Vladimir Ivanovich, PhD (Phys. & Math.), Senior Research Scientist, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail: ovoch-isi@outlook.com; ORCID 0000-0003-4999-8142

Shevchenko Serhiy Anatoliyovych, Ph.D., Senior Researcher, Iron and Steel Institute named after Z.I. Nekrasovof the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail: shev_serg@i.ua, ORCID 0000-0002-9287-9177

Tovstopyat Alexander Petrovich, PhD (Engin.), Researcher , Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107

Fleer Leonid Aleksandrovich, Researcher, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107

Dynamics of oscillations of the “liquid bath – lance” system during injection processing of the melt in the ledle. Summary.

The aim of the study was to evaluate the influence of key waveform factors on the dynamics of the process during injection molding of cast iron with granular magnesium in ladles, their significance and relationship between them. Based on the theories of wave motion of liquid layers, a mathematical model has been developed that allows to investigate the oscillatory processes in the ladle during the processing of cast iron melt with granular magnesium. The model involved the processing of cast iron by injection of granular magnesium through the tuyeres of devices that are immersed in the melt. The oscillating system “Liquid bath – lance” is considered on the example of the bath of a heavy – duty filling bucket with its own frequency – 0.47 Hz. The influence of the most probable oscillation sources (natural frequency of the lance oscillation and the frequency of the conditional source) on the amplitude-frequency oscillations of the system elements is calculated. It is established that in addition to the natural frequencies of these elements, the system has two more natural oscillations. Given that the mass of the melt is much greater than the mass of the lance, it practically determines the behavior of the system during its excitation. That is, the system responds only to those excitations in which the frequency is close to the natural frequency of the liquid bath. In turn, it is shown that the natural frequency of the bath is largely determined by its diameter at the top. In practice, it is necessary to know the resonant frequencies of the liquid bath, the tuyere device, as well as all other sources of oscillations (gas jet decay, and oscillations of pop-up bubbles). Accordingly, it is necessary to try to dampen the amplitude with this dangerous resonant frequency. To reduce the oscillation amplitude of the bath surface when treating cast iron with granular magnesium, it is recommended to first estimate the natural resonant frequency of the liquid bath, and then select design solutions and processing parameters, avoiding dangerous frequencies close to the natural frequency of the bath. However, it should be noted that the spectrum of oscillation frequencies in the purl zone is quite wide and, of course, contains dangerous low frequencies.
Key words: amplitude, frequency, oscillating system, liquid bath, lance, mathematical model.

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