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6INCREASING THE DURABILITY OF HEAVILY LOADED GEARS
Bukayeva A.Z.
Bukayeva Amina Zakharovna - Senior Lecturer, DEPARTMENT OF MECHANICAL ENGINEERING, CASPIAN STATE UNIVERSITY OF TECHNOLOGY AND ENGINEERING NAMED AFTER SH. ESENOV,
AKTAU, REPUBLIC OF KAZAKHSTAN
Abstract: the article provides an analysis of research on the problems of improving the quality of broadcasts. The advantages of modifying the wheel profile as a way to improve the performance of gears. The most promising technological processes of mechanical hardening of the working surface of gears, including running wheels and shot blasting hardening.
Keywords: strong, heavy gears, modification profile duties, shot blasting, hardening.
UDC 621.9
Increasing the durability of heavily loaded gears is a very complex and interrelated set of various problems. Underestimating the factors affecting the service life of wheels at all stages of their manufacture and operation dramatically reduces the service life of the equipment as a whole. Solving the problems of durability operation requires the use of the entire arsenal of technological means in order to ensure high quality of working surfaces, since it is the surface layer that has a great influence on their operational characteristics [1].
As shown in [2], there are two concepts of modification: natural and obtained by deliberately changing the shape of the profile of the teeth. The natural modification of tooth profiles is understood as some wear of the tooth head during the operation of the wheels or some grinding of a part of the profile on the head caused by a decrease in the pressing of the grinding wheel at the moment of its disengagement from the wheel.
The effectiveness of the profile modification is influenced not only by the parameters, but also by the shape of the flanking. The authors evaluated the effectiveness of various forms of profile modification, namely rectilinear and curved (circular shape), by reducing the specific circumferential dynamic force and the noise level of gears. It was found that for heavily loaded wheels, the circular shape is more effective, since for this shape the value of the coefficient of reduction of the specific circumferential dynamic force, which is the ratio before the profile modification to after modification, is higher than for the rectilinear shape.
It is established that the majority of gears in the process of operation experiences dynamic loads that vary according to a symmetrical alternating or asymmetric alternating cycle. Unavoidable defects in the shape and relative position of the teeth in the gears cause non-smooth operation of the transmission mechanism, characterized by noise, vibrations and additional dynamic loads that occur both directly on the transmission teeth and in the drive units.
With all the main types of loads, the surface layers of the metal are the most stressed. At the same time, these layers are the most weakened, since the maximum number of stress concentrators (risks, undercuts, galtels, etc.) is concentrated on the working surface of the gears.
Therefore, technological processes associated with mechanical hardening of the working surface of the gears and causing an increase in their bending strength are promising for modern mechanical engineering.
One of the methods of surface deformation hardening of gears is widely used - buckling with a shot. Numerous experiments and factory practice have proved the high efficiency of shot hardening of various parts made of ferrous and non-ferrous metals. The use of strain hardening by shot was particularly effective on parts with surface stress concentrators and with a decarbonized surface operating under cyclic loads.
Studies conducted on non-hardened and hardened gears [2] have shown that the endurance limit of the teeth increases by 10-18% as a result of riveting with shot.
An increase in the operational durability of cemented gears testifies to the effectiveness of riveting with shot. The studies carried out on gears made of 20KHNM, 25KHGM and ZOHGT steels show that the operational durability as a result of riveting increases by 2.5 - 3 times.
References
1. Bol'shakova M.Ju. Issledovanija vlijanija sostava i struktury uprochnennogo poverhnostnogo sloja na dolgovechnost' tjazhelonagruzhennyh zubchatyh koles: dis. ...kand.tehn. nauk: 05.16.09. Perm': RGPPU, 2011. 149 s.
2. Jakovleva A.P. Poverhnostnoe plasticheskoe deformirovanie cementovannyh zubchatyh koles // Progressivnye tehnologii, konstrukcii i sistemy v priborostroenii i mashinostroenii: Trudy Vserossijskoj nauchno-tehnicheskoj konferencii. M.: 2001. T. 1. S. 48-50.
