PARAMETERS OF THE WORKING SURFACE OF AUTOMOTIVE TRACTOR ENGINE PARTS IN THE ENGINE WORKING PROCESS

Аннотация

Parameters of the working surface of parts of automotive and tractor engines play an important role in the efficient operation of the engine. Working surfaces, such as piston, cylinder, and valve surfaces, their smoothness, rigidity, and dimensions determine the engine's performance. Optimal working surfaces contribute to effective control of temperature and pressure in the working medium, reducing friction. Also, the surface parameters increase service life and reduce the risk of malfunctions. Therefore, ensuring the quality of the working surfaces andtheircorrect adjustmentguarantees uninterrupted andreliable engine operation. Keywords: Tractor, engine, working surface, parameters, efficiency Introduction.Itisknownthatthecomponentsthatdeterminetheservicelifeofinternalcombustion engines include the crankshaft, bearing inserts, cylinder liner, and piston ring. One of the convenient and simple methods for increasing their working period is rubbing them together and mutuallypolishingthemunderoptimalconditions. Until recently, friction smoothing of friction surfaces was understood as an increase in the contact support surface between the joint parts as a result of mechanical cutting and crushing of micro-roughs on their surfaces. It is said that the increase in this contact surface leads to a decrease in the amount of load on their unit surface during operation and, as a result, a sharp decrease in wear y. Recently, the idea has been put forward that the wear resistance of joint parts e depends not only on the increase in the supporting surfaces but also on the quality of the parts' surfaces [1]. The quality of friction surfaces depends on the type of material, microstructure, physical- mechanical and chemical properties, macro- and microgeometry, the type of heat treatment, and thequalityof grinding under optimal conditions[2]. Small contact surface of friction surfacesleads to an increase in the specific load, and as a result, the local pressure and temperature on the friction surfaces increase sharply. According to Professor N.G. Polyushkin [3], who analyzed Bowden's experiments, the local temperature can reach 1000°C without oil friction. As a result, the peaks of the microplatitudes on the rubbing surfaces collide with each other, become spot-welded, and merge in an instant, forming "bridges," but they immediately break under the influence of the friction force, and small particles and even whole grains separate from therubbing surfaces. Whenthe pressure between the friction surfaces of the parts is small, elastic collisions occur, and when thepressure is high, thecollision becomes plastic. In thelatter case, friction leads to plastic displacement of the material of the outer layer of the parts, and as a result, the friction surfaces become polished. For this reason, when the friction surfaces of parts are mutually smoothed, their polishing occurs and an amorphous layer is formed. In this case, as a result of the displacement of the material of the peaks of the micro-roughness on the surfaces into a plastic state, thedepressionsof themicro-roughness are partially filled. Result and discussion. Details manufactured on metal-cutting machines have uneven surfaces due to machining. It consists of microscopic heights and depressions invisible to the eye, and https://ijmri.de/index.php/jmsi volume 4,issue7,2025 237 they represent surface roughness [5]. For example, after choning the cylinder liner, the root mean square value of the height of the microplatforms will be Ra=0.4-0.8. In addition, due to the uncertainty of the machine-piece-tool system, the surfaces of the parts deviate from the ideal geometric shape. Its magnitude depends on the physical and mechanical properties of the material from which the part is made, the condition of the machine tool, the cutting regime, the conditionof thecutting tool,etc. [4]. When assembling engines, the mutual arrangement of the friction surfaces of the connecting parts - piston and sleeve, piston and piston ring, connecting rod and piston pin, connecting rod andcrankshaft journals and bearings -has a deviation from theideal geometricarrangement. All these deviations are microgeometric deviations, which lead to a violation of the accuracy of the relative positioning of the cylindrical surfaces of the parts during engine assembly. Such distortions include deviations from the geometrically correct positioning of the parts' axes: non- parallelism, non-perpendicularity, and adjacent beats. [5]. The presence of such deviations leads to the fact that the actual support friction surface, on which the surfaces of the joint parts are in contact with each other, is very small. This, in turn, leads to an increase in the load on the unit friction surface by tens of times. This situation was proven in the experiments conducted by Bowden and Taylor. When studying the influence of pressure on the contact surface of a steel plate with a total surface area of 21 cm2, they found that at a