Characteristic of wear of landing surfaces of crankcase of gearbox of car
Students Name: Matsiburka Oleh Mykhailovych
Qualification Level: magister
Speciality: Motor Vehicle Transport
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: full
Academic Year: 2023-2024 н.р.
Language of Defence: ukrainian
Abstract: Experience in the operation of automotive vehicles (AMV) shows that deviations from standard operation or complete failures of systems by 65-85% occur due to the failure of machine elements caused by surface destruction due to wear and associated processes (volumetric, in particular fatigue and surface: erosion , cavitation, fretting corrosion, etc.). At the same time, quantitative indicators of friction (wear, dynamic coefficient of friction) are closely related to changes in the properties of metals and contacts on micro-uniformities of surfaces. Therefore, the question of a more in-depth study of the work processes that take place in the friction nodes of automobile units becomes urgent. Object of research: tribological processes in body parts of automobile units. Subject of the study: the regularity of the distribution of the wear values of the holes for the gearbox crankcase bearings. The purpose of the work is to determine the quantitative characteristics of the wear of the landing surfaces of the gearbox housing of the car. In chapter 1, the general principles of the defectology of AMV parts are given. A large array of various processes takes place in automobile parts and its components, which in the end determine both the operation of the car as a whole and its parts, in particular, as well as their aging and the occurrence of failures. The processes occurring in the ATZ can be divided into the following types: working, auxiliary and destructive [1]. Work processes include useful ones that determine the functioning of the AMV in general and its subsystems (parts, nodes, mechanisms, aggregates, systems). Auxiliary processes do not create appropriate operational properties, but contribute to the normal flow of work processes. Auxiliary processes include engine cooling processes, since without forced cooling, work processes will become impossible. The processes of lubrication of the surfaces of couplings operating in the friction mode, etc., can be attributed to the same processes. By their nature, auxiliary and work processes should be classified as stationary mode. Destructive processes are considered random, although each of them when considered in isolation can be taken as stationary. They have coherent properties, that is, they can weaken or strengthen each other. Most of the destructive processes are connected to one degree or another with thermal energy, which affects the properties of the part. The dependence of work processes on time or mileage is decreasing, and destructive ones are increasing. At the same time, carrying out current repairs after certain periods of time restrains the decrease in the level of work processes, as well as the increase in the level of destructive ones. However, with the passage of time, the destructive processes reach such a level that the AMV reaches its limit state and requires major repairs. Chapter 2 discusses the types of friction that occur in the coupled parts of the automatic transmission system during its operation. These include: dry, boundary, liquid, visco-fluid, viscoplastic, semi-fluid friction, sliding and rolling friction. The characteristics and features of each of them are given. The effect of the state of the surface of the counterbodies and the composition and properties of lubricants on the friction processes and wear of the contact surfaces is described. As a separate case, the rolling process is considered, during which the friction force is ten times smaller than the sliding force. As for rolling bodies, as in the case of sliding, friction forces act on their surfaces. The presence of adhesive coupling almost does not affect the rolling friction forces, but it significantly contributes to the wear of the surfaces of the rolling bodies. In chapter 3, the technical conditions for the defecting of gearbox housings of KrAZ-65053 cars are given, in which characteristic damage to their structural elements is noted, the nominal and repair dimensions are indicated, and the conclusions regarding the methods of their elimination are outlined [3]. Based on the results of experimental measurements of the amount of wear of the front bearing surfaces of the intermediate shaft of 75 gearboxes of the KrAZ-65053 car, an empirical distribution of this value was obtained, its statistical characteristics (root mean square deviation and mathematical expectation) were calculated, and a distribution curve was constructed [4]. It was aligned according to normal, gamma and log-normal distributions. The application of the Pearson test made it possible to identify the most consistent distribution law (log-normal). Key words: automotive vehicle, working, auxiliary and destructive processes, types of friction, dynamic coefficient of friction, lubricant, statistical distribution, Pearson’s criterion. List of used literary sources 1. Fornalchyk Ye.Yu. Tekhnichna ekspluatatsiia ta nadiinist avtomobiliv: navchalnyi posibnyk / Ye.Yu.Fornalchyk, M.S.Oliskevych ta in.- Lviv: Afisha, 2004.- 492 s. 2. Volchenko O.I. Trybolohiia: Pidruchnyk dlia VNZ /O.I.Volchenko, M.V.Kindrachuk ta in.-Ivano-Frakivsk: Vyd-vo Prykarpatskoho nats. un-tu im. V. Stefanyka, 2015.- 372 s. 3. Tekhnichni umovy na kapitalnyi remont avtomobilia KrAZ-65053. - K.: Tekhnika, 1996.- 527 s. 4. Drahomyretska Kh. T. Teoriia ymovirnostei ta matematychna statystyka: navch. posibnyk /Kh. T. Drahomyretska, O. M. Rybytska ta in. – Lviv: Vyd-vo Lvivskoi politekhniky, 2012. – 396 s.