Actual Problems in Machine Building 2016 No. 3

Актуальные проблемы в машиностроении. 2016. №3 Технологическое оборудование, оснастка и инструменты ____________________________________________________________________ 329 13. Технологическое оснащение процессов изготовления конструктивно сложных деталей: монография / Е.А. Кудряшов, С.Г. Емельянов, Е.И. Яцун, Е.В. Павлов. – Старый Оскол: ТНТ, 2013. – 268 с. 14. Kudryashov E.A . Validated methods of parts machining for nonleaking hydraulic cylinders in drilling installations // Journal of Mining Science. – 2012. – Vol. 48, N 5. – P. 870–873. 15. Pavlov E.V., Chervyakov L.M . Some provisions of rational contact conditions for a composite cutting tool during turning operations on intermittent areas // Applied Mechanics and Materials. – 2015. – Vol. 788. – P. 102–107. ENSURING MECHANICAL PROPERTIES OF THE ROTATIONAL PARTS WORKING IN THE CONDITIONS OF IMPACT LOADINGS Pavlov E.V. , Ph.D. (Engineering), Associate Professor, e-mail: evp.kstu@mail.ru Southwest State University, 94, 50 let Oktyabrya str., Kursk, 305040, Russian Federation Abstract The rotational parts perceiving impact sign-variable loading have to possess the high level of hardness and a limit of fluidity. Substantially mechanical properties are influenced by structure and the maintenance of the alloying elements of materials of rotational parts. The used steel brands contain rather large number of the nonmetallic inclusions which are concentrators of tension and considerably reducing resistance to fatigue failure. Besides, fundamental value renders a choice of a method of heat treatment. Operability of basic parts and a resource of boring machines substantially depend on thermal hardening of the material of parts providing the best combination of the demanded indicators of durability, hardness, impact strength. For providing the maximum indicators of impact strength became with the hardness of 38 … 42 HRC most rational heat treatment is isothermal training. In the steel strengthened on technology of isothermal quenching, cracks grow twice more slowly, than in the steel strengthened by quenching and tempering. It should be noted that formation in the parts working in the conditions of impact and cyclic loading, structures with a low durability is irrational. Despite high rates of impact strength, steel in a low-strength state (less than 30 HRC) possesses low resistance to fatigue failure. Keywords Rotational parts, mechanical properties, heat treatment, isothermal quenching, impact strength, fatigue failure