ANALYSIS OF THE MICRO PROFILE FORMATION OF MACHINE ELEMENT SURFACES AT MACHINING STAGES AND RUNNING-IN CONDITIONS OF BOUNDARY FRICTION

Abstract

An approach is proposed which is based on the theory of random processes and which allows carrying out an objective comparative analysis of the results of forming of surface roughness profiles of sliding friction joint elements both after machining and during operational run-in. The research relevance is determined by the task of forming a surface roughness profile by various technological methods, which corresponds to or is close to the operational one formed during the running-in of the sliding friction joint elements, that would allow manufacturing products which would start operating in conditions close to normal wear. The studies evaluate the influence of technological factors on forming roughness profiles by turning options and round grinding methods followed by surface plastic deformation by diamond smoothing, electromechanical machining, etc., as well as the influence of the run-in processes carried out on the test bench. A qualitative assessment of the forms of amplitude-frequency characteristics of models forming element surfaces is accepted as the identity criterion of processes forming microprofiles of element surfaces. The paper presents a method of experimental verification of the surface roughness profile for stationarity and ergodicity, which can be used to analyze other random sequences appearing in the practice of tribotechnological research. The construction of autocorrelation functions of the surface roughness profile before and after running-in makes it possible to find out the influence of technological heredity on forming a microprofile while surface machining and running-in of parts. The calculation of indicators to evaluate the theoretical spectral densities of roughness profiles and the construction of amplitude-frequency characteristics of forming surface roughness by various technological methods and during run-in allows choosing an effective method of machining parts, which significantly reduces the run-in time of sliding friction pairs. Studies have shown that surface plastic deformation should be used as the finishing treatment of parts, which allows to obtain a roughness profile of sliding friction surfaces close to the operational one.