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Contributions to the study on the precessional gearing teeth processing accuracy

Author: Vaculenco Maxim
Degree:doctor of engineering
Speciality: 05.02.02 - Theory of machines and machine elements
Scientific adviser: Ion Bostan
doctor habilitat, professor, Technical University of Moldova
Scientific council:


The thesis was presented on the 28 November, 2008
Approved by NCAA on the 26 February, 2009


Adobe PDF document1.42 Mb / in romanian


CZU 621.833.6

Adobe PDF document 14.49 Mb / in romanian
185 pages


precessional motion, gearing, gear wheel, profile, model, quality, accuracy, error, MMC, coordinate, computer, technology, tool.


Doctoral thesis on the awarding of the scientific degree of doctor of technical sciences, specialisation 05.02.02 – “Theory of Machines and Machine Parts”, Technical University of Moldova, Chişinău, 2008. The thesis is presented in the form of manuscript. The author published 18 scientific papers related to the topic of the thesis and registered 5 patents in the Republic of Moldova.

This work presents the results of theoretical and experimental research on precessional planetary transmissions that was carried out by the author in the period 1996-2008. In this context the author has made a number of original contributions to the elaboration of control method for gear wheels with non-standard profile of teeth, for the elaboration of a new digital command integrated technology for gear wheels processing, etc. Based on the main errors analysis which influences the teeth profile accuracy, the teeth profile modification method for diagram error compensation was proposed. The diagram error is being generated due to the peculiarities of sphero-spatial motion of a gear wheel. In this respect the tooth surface with profile modification was described analytically. The comparative analysis of teeth profiles with/without profile modification for various geometrical parameters of teeth was carried out. For the generation of tooth modified profile, the device cam profile description equations have been elaborated. This device provides the diagram error compensation for the connecting mechanism of the generation device for gearing. To simulate the influence of manufacturing and mounting errors of processing device components on teeth profile the computerized sample of teeth processing device with modified profile and tool precessional motion have been elaborated. Based on multi-criteria analysis of manufacturing and mounting errors, the relation for the determination of the presumable boundary error of the processing device of the gear wheel from the precessional gearing was obtained. Aiming at the fulfillment of teeth manufacturing accuracy control the software for the generation of the mathematic model of gear wheels teeth profile from the precessional gearing with/without profile modification was designed. It will be utilized for the design of the wheel solid model in CATIA V5R18 and SolidWorks 2008 design systems. A new procedure for the estimation of manufacturing accuracy of gear wheels teeth from the precessional gearing was proposed based on the physical (real) comparative model with the mathematical (computer based) one by applying a specialized software. For the digital command integrated processing of gear wheels teeth a new technology has been developed which allows increasing the processing accuracy by approximately 2 steps of the accuracy class.