Supervisor of master's dissertation is Konarev V.G.

RESEARCH OF STRUCTURE AND PROPERTIES OF TOOTHED FIXATIVE ELEMENTS
 

 The details of gearings are important component parts of various machines and mechanisms, it is therefore necessary to examine the increase of their longevity as important task. Thus for development of the rational modes providing the high level of operating firmness of toothed elements, it is necessary to know the reasons of output of their line-up.

It is known that the low capacity of such wares more frequent than all is related to tireless destruction (80-85%), wear of butt ends (10-15%), tireless painting of working surfaces, plastic deformation of surfaces of friction, jamming, teasers, wear and dents on them (in a sum 3-5%).

The decline of danger of breakages of gears can be attained by the choice of the optimum modes of heat treatment, providing consolidating of surfaces of contact and diminishment of wear due to the increase of their hardness. In addition, not unimportant part is acted by technological measures cooperant to the removal of different defects (rough risks after tooling, pryzhogy at polishing and other).

A structure and properties of the power conical toothed fixative elements set in machines on production of welding powder-like wire with the purpose of exposure of reasons of their low firmness for the subsequent choice of methods of its increase was explored in this work.

Macrostructural researches were shown, that toothed fixative elements had broken ranks both from breakage of gears and from crumpling and deformation of their contact surfaces.

It was set by the spectral analysis, that these details are made from steel proper on chemical composition to the brand 40Х.

The results of measuring of mykrotverdosty testify with the use of mykrotverdomera PMT-3, that its change in the transversal section of tooth carries difficult character. In a superficial layer, in depth to 0,15…0,20 mm of its value hesitates in the interval 2000….3000 Н/мм2, after there is growth to 4500…5000 Н/мм2 in the layer of toschynsoy to 0,4…0,45 mm with the subsequent decline.

At the study of microstructure the presence of obezuglerozhennogo layer on a surface was exposed, and on greater distance from her a structure consisted of mixture of beynyta, ferryta and martensyta (the mean value of hardness is at the level of 35…39 HRC).

Thus, it is possible to do a conclusion, that low firmness of the indicated details is related to violations of technology of tempering and vacation, thus both at heating (oxidizing atmospheres) and at cooling, obviously, from the delays at the transfer in a tempering tank.

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