ТЕХНОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ВОССТАНОВЛЕНИЯ ШЕЕК КОЛЕНЧАТЫХ ВАЛОВ В СВЯЗИ С ИХ СТАРЕНИЕМ В ПРОЦЕССЕ ЭКСПЛУАТАЦИИ

Abstract

Numerous publications in the open press on the restoration of crankshaft necks by various methods are known. They provide recommendations for applying coatings to worn necks. However, most work lacks studies on the change in fatigue strength and wear resistance of crankshafts. (Research purpose) The research purpose is studying the technological features of recovering the crankshafts due to their aging during operation. (Materials and methods) As objects of research, crankshafts of diesel engines of various repair sizes were selected. The surface hardness of the necks was studied using portable hardometers in the zone of the greatest and least wear. The data were processed using mathematical methods and compared with allowable hardness values for new and worn necks. Fatigue tests were carried out on machines when the bending moment was loaded along a symmetrical cycle before the appearance of a fatigue crack and final destruction for various coating methods. (Results and discussion) The surface hardness of the necks of extremely worn shafts is reduced by 10 HRC compared to the hardness for new shafts. The reason for the decrease is due to the operation of the neck in dry friction conditions, which causes heating of the surface and, as a result, tempering. The limit of endurance of limit worn shafts in comparison with the limit of endurance of new crankshafts is reduced by 20-25 percent. This is due to the accumulation of fatigue failures. Laser hardening is proposed to increase life of worn-out shafts with reduced hardness. Technological features have been developed for restoring the necks of extremely worn crankshafts. (Conclusions) The aging of crankshafts occurs with a decrease in surface hardness by 10 HRC units and a decrease in the endurance limit by 20-25 persent. Invention proposes laser thermal resistance of necks with reduced hardness, which increases wear resistance by 1.9- 2.6 times.