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Determination of hydrodynamic power losses in a gearing

100%

Stavytskyi V. , Bashta O. , Nosko P. , Tsybrii Y.

Acta Mechanica et Automatica

2022

tom Vol. 16, no. 1

1--7

Despite the relatively numerous experimental studies, there are few published works on the topic of development of mathemati-cal models that describe the hydrodynamic processes in gears. There is no generic analytical model that integrates all types of losses. The purpose of this work is to develop a modern generalised methodology for calculating the hydrodynamic power losses of high-speed gears. For each gear, partially or fully immersed into an oil bath, the power spent to overcome the hydromechanical resistance can be represented as the sum of the following: the Coriolis force moment arising from the radial movement of the oil in the tooth spaces of the rotating gear, the viscous friction forces moment on the periphery of the gear addendums in the oil bath and the viscous friction forces moment at the face of the gear in the oil bath. The hydrodynamic power losses due to the Coriolis force action, viscosity friction losses at the periphery of the gear and the viscosity friction at the face of the gear (both turbulent and laminar modes) were observed separately. From the mathematical simulation of the rotation processes when the gear is immersed into the oil bath, an analytical dependence was obtained. It allows predicting the influence of the geometrical parameters of the gearing on the hydrodynamic power losses. Analysis of the calculation results of the power losses due to the action of hydraulic resistance forces and results from experimental studies is provided for several gears with different hydromechanical parameters. The proposed method of calculating power loss due to hydromechanical resistance of the oil bath to the rotation of the gear gave results that were close to the experimental data. Acceptable coincidence of theoretical and experimental results allows recommending the received analytical dependencies for practical calculations of high-speed gears.

The Synthesis of Dwell Mechanisms on the Basis of Straight-Line Linkages with Fivefold Interpolation Nodes

88%

Kharzhevskyi V. , Pashechko M. , Tatsenko O. , Marchenko M. , Nosko P.

Advances in Science and Technology. Research Journal

2021

tom Vol. 15, no 1

18--25

The paper deals with the problem of kinematic synthesis of dwell linkage mechanisms which are based on the four-bar linkage with a coupler point that traces a curve with a straight-line part. It enables to obtain a dwell of the output link of the mechanism, but the main goal is to find such parameters of the mechanisms that hold the required conditions of the designer: necessary dwell time, to satisfy the necessary cyclogram of the machine with taking into account the number of additional parameters. The main problem is to carry out the kinematic synthesis of the basic straight-line linkage that can be done by the kinematic geometry methods. In this paper it was shown that the fivefold interpolation nodes of the coupler curve with the tangent line can be successfully used to satisfy the necessary criteria. As a result of the carried out studies, the regions of existence of such mechanism parameters were determined enabling to carry out an optimization procedure using different criteria.

Investigation of structure formation and tribotechnical properties of steel plasma coatings after chemical-heat treatment and liquid-phase impregnation

75%

Mediukh R. , Mediukh V. , Labunets V. , Nosko P. , Bashta O. , Kondratenko I.

Acta Mechanica et Automatica

2022

tom Vol. 16, no. 4

382--387

The paper is focused on the studies of the microstructure development and physical and mechanical properties of metal-matrix composite coatings based on steel 11Cr18MoWCu deposited using plasma and galvanoplasma methods. The expediency of combining gas-thermal spraying processes of plasma coatings with open porosity up to 16%–18%, with their subsequent thermodiffusion saturation (chromium plating) or liquid-phase impregnation with eutectic alloys of previously applied Ni–B galvanic layer, is shown. The study of the tribotechnical properties of the proposed coatings showed a significant improvement in their performance under conditions of various types of intensive wear, as well as in corrosive environments.