The paper covers the development and analysis of a model of the true viscous lubricant movement in the working gap of a radial sliding bearing with a non-standard support profile having a fluoroplastic composite polymer coating with a groove on the shaft surface. The authors obtained new models based on the classical equation in the approximation for the “thin layer” and the continuity equation describing the laminar pattern of movement of a lubricant with the viscous rheological properties. The results of the numerical analysis of the developed models allowed obtaining a quantitative assessment of the efficiency of the bearing bush support profile and the polymer-coated shaft with an axial groove. To complete the set of studies and verify theoretical insights, the authors carried out the experimental research. The novelty of the work lies in the development of an engineering calculation technique that allows determining the magnitude of the main tribotechnical parameters of a radial sliding bearing (hydrodynamic pressure, load capacity, and friction ratio) and expanding the area of practical application of the developed engineering calculations. The design of the radial bearing with a fluoroplastic antifriction composite polymer coating, a 3 mm wide groove, and a special support profile ensured the stable shaft ascent on the hydrodynamic wedge, which experimentally confirmed the correctness of the results of theoretical studies of sliding bearings with a diameter of 40 mm at a sliding speed of 0.3–3 m/s and a load of 13–65 MPa.
In the study, based on the micropolar fluid flow equation for a “thin layer”, the continuity equation, the equation describing the profile of the molten contour of the guide coated with a low-melting metal alloy, and the equation for the mechanical energy dissipation rate, asymptotic and exact self-similar solution has been found for the zero (without considering the melting) and first (considering the melting) approximation of wedge-shaped support with the slider support profile adapted to the friction conditions and the low-melting metal coating of the guide surface. The research has taken into account the pressure dependence of the lubricant rheological properties and the melt having micropolar properties in the laminar flow regime. Analytical dependencies have been obtained for the molten surface profile of the low-melting metal coating of the guide and the field of velocities and pressure for the zero and first approximations. Also, the basic performance characteristics of the friction pair under consideration have been determined: the bearing capacity and the friction force. The impact of parameters determined by the coating melt, adapted to the support profile friction conditions, and the parameter characterizing the pressure dependence of the lubricant viscosity on the bearing capacity and friction force has been estimated.
Introduction. In modern heavy-loaded friction units, metallopolymer coated bearings operating in the boundary friction mode are widely used. Their successful application is provided by the viscoelastic deformation of these coatings under load. To pass from boundary friction to liquid friction, it is required to create a bearing hydrodynamic wedge. Currently, the use of journal bearings with polymer-coated grooved support ring is hindered by the lack of a methodology for their calculation. This work analyzes a model of movement of a micropolar lubricant in the operating clearance of a journalbearing with a nonstandard support profile having a PTFE composite coating with a groove on the bearing surface. The study aims at establishing the dependence of the stable hydrodynamic regime on the width of the groove on the surface of the bearing profile. Materials and Methods. Tribological tests of journal bearings with a nonstandard bearing profile having a polymer coating with a groove on the surface were carried out on samples in the form of partial bushes (blocks). Using the equation of movement of a lubricant with micropolar rheological properties, as well as the continuity equation, new mathematical models were obtained that took into account the width of the groove, polymer coating, and nonstandard bearing profile. Results. A significant expansion of the applicability of design models of journal bearings with structural changes has been achieved. Polymer-coated bearings with a groove provided a hydrodynamic lubrication mode. The results obtained allowed us to evaluate the operational characteristics of the bearing: hydrodynamic pressure value, load capacity, and coefficient of friction. Discussion and Conclusions. The design of polymer coated journal bearing and a groove 3 mm wide on the surface of the liner provided a stable ascent of the shaft on the hydrodynamic wedge, which was validated experimentally. The experiments were carried out for journal bearings with a diameter of 40 mm with a groove 1–8 mm wide, at a sliding speed of 0.3–3 m/s and a load of 4.8–24 MPa.
The study objective is to find out the regularities of a stable hydrodynamic regime. The paper is devoted to the analysis of a model of a radial sliding bearing with a profile adapted to friction conditions, which also has a polymer coating with a groove on the support. Research methods: there are proposed new models describing the movement of the lubricant in the approximation of a "thin layer", the continuity equation taking into account the dependence of viscosity on pressure. The novelty of the work is in the development of a methodology for engineering calculations of the bearing structure with a polymer coating, a groove and an adapted profile. As a result of the study, a significant expansion of the possibilities is achieved to apply in practice the calculation models of a radial sliding bearing with a polymer coating and operating in a hydrodynamic lubrication mode. Conclusions: the design of a radial bearing with a polymer coating and a groove 3 mm wide, as well as adapted to the loading conditions of the support surface with a profile provide a stable shaft lift-up on a hydrodynamic wedge.
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