Shepelenko I. Scientific bases of technology of drawing antifriction coating with use of plastic deformation

The dissertation is devoted to the solution of a scientific and technical problem consisting in creation of scientific bases of technology of drawing antifriction coverings with use of cold plastic deformation for increase of quality of surfaces of friction of details from low-plastic materials. An experimental model of contact interaction of a single micro-inequality with a tool at FANT was developed, which allowed to establish the basic laws of the process and to ensure effective micro-cutting and filling of micro-cavities with antifriction material. To raise the quality of application of antifriction coatings, the use of deforming drawing is proposed to improve the adhesive interaction with the base material, to obtain a working surface of the part with improved physical and mechanical qualities and roughness close to equilibrium. It is established that SCH20 cast iron can be plastically deformed only at negative values of the stress stiffness index, which allows to formulate the following position: treatment of holes in cast iron products by deforming drawing is possible only in the absence of plastic deformations near the outer surface of the product adjacent to the hole. A study of the mechanics of deforming drawing is performed. It is shown that in the presence of critical contact pressures in the contact zone, zones of local plastic deformation appear. The influence of the tool geometry on the parameters of the stress-strain state, the history of deformation and the service life of the used plasticity are investigated. Technological recommendations for the choice of tool geometry during deforming drawing are offered. It is shown that the basis for the application of antifriction coatings are adhesive areas of setting, which are formed due to the interaction of the tool with the micro-roughness of the treated surface. A statistical mathematical model has been developed to determine the influence of technological factors on the quality of antifriction coating. The optimal options for combining technological factors that improve the quality of the coating are identified. The method of calculation of the stress-strain state in the antifriction coating applied to the working surface of the cylinder liner is substantiated. The calculation of coating stresses in the contact zones of the piston rings is performed. An accelerated test method for wear resistance is proposed, which consists in modelling the real operating conditions of the piston ring in the area of its contact with the surface of the sleeve. On the basis of the conducted research new technological processes of drawing antifriction coverings with use of FANT and deforming drawing are developed. Key words: technology, antifriction coating, finishing antifriction non-abrasive treatment, microcutting, deforming drawing, plasticity, stress-strain state.