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CNAA / Theses / 2019 / June /

Technological processes generating non-standard profiles of precessional gear

Author: Mazuru Sergiu
Degree:doctor habilitat of engineering
Speciality: 05.03.01 - Procedures and equipment for mechanical and physical - technical working (according to branches)
Scientific consultant: Ion Bostan
doctor habilitat, professor, Technical University of Moldova
Institution: Technical University of Moldova


The thesis was presented on the 17 June, 2019
Approved by NCAA on the 27 September, 2019


Adobe PDF document4.02 Mb / in romanian


CZU 621.883+621.91/92

Adobe PDF document 16.00 Mb / in romanian
360 pages


precessional transmission, gear non-standardized, profile, technology tooting, grinding, cinematic technology system, cutting tools, machine tool, device, contact line, cinematic process


Thesis structure. The thesis includes introduction, six chapters, conclusions, bibliography of 349 titles, 3 annexes, 319 basic text pages, 215 figures, 7 tables. Publications on the thesis topic. The results are published in 109 scientific works (twe monographs, articles in journals, communications at international conferences, including 29 patents).The research presented in the thesis and on the basis of published works solved the main scientific problem: the development of the theory of gearing of a gear wheel using a disk-shaped tool with profiled periphery, and also based on established laws, connections, developing a system for ensuring gearing profiling.

Field of study: The scientific basis of technological methods of engendering non-standard profiles of precessional gear.

The aim of the work. The aim is to elaborate the technological processes for generating the profiles of precession gear teeth with non-standard variable profile with the extension of the technological possibilities, to increase the quality and precision of the profiled surfaces. Research objectives: elaboration of the kinematic concept of the technological process of generating by rolling of precession gears with variable and non-standard profile with peripheral profile tool; elaboration of the physico-mathematical model of the rolling process of the convex-concave profile with sphericaldisk movement tool; elaboration of the physical model of realizing the process of generating the convexconcave profile with the "disk-tool" with the sphero-spatial motion; the determination of the surface quality indexes processed depending on the shape of the tool peripheral shape, the tool movement kinematics and the rectification procedures; Determination of geometric deviations and determination of admissible technological errors of toothed gear teeth; identifying the nature of technological errors and geometric deviations according to the precision of machining the gears; developing practical recommendations to ensure the quality and precision of the dental flanks of the treacherous planetary transmissions. Novelty and originality of scientific: consists in the premiere development of the mathematical and physical models of a new principle of generating the teeth of precession gears with variable (non-standard) convex-concave profile of the teeth with a spherical-disk movement tool.

The new generation principle allows: to extend the technological possibilities of dental teeth generation with smaller diameters (d = 20 mm) and to the largest ones, to increase the productivity of the profile generation, ensures the precision of the teeth of the precession transmissions with variable nonstandard profile by the rolling method with peripherally shaped abrasive disk.

Theoretical significance. For the first time, the mathematical model of the teeth generation process with non-standard convex-concave dies was developed with kinematics consisting of 4 movements: autonomous movement – main cutting movement – rotation of the abrasive tool with the frequency n(1), the movement of auxiliary cutting, quickly performed as a linear movement along the toroothll,in g motion – slow rotation of the wheel at an angleΔ Θ during a double stroke of the abrasive tool along the tooth, coordinated movement with wheel running – displacement of the head in a tangential direction to the point of contact.

The value of the work. The new convex-concave-shaped teeth surface design with a sphericaldisk movement tool with a fixed point has been proposed and made in the equipments (29 inventions patents have been obtained, the equipment was developed, executed and implemented, devices and tools.

Implementation of scientific results. The results were implemented at ARP GmbH Alpirsbah (Germany), according to the implementing act. The work Pre-Planetary Transmissions in 1998 was appreciated with the highest destination in the field of science and technology – the State Prize of Republic of Moldova. As a co-author I was awarded the title of Laureate of the State Prize of the RM in the field of Science and Technology. Certain chapters of the thesis are included in the curriculum of the Department of Machine Building Technology for the training of specialists in specialty 521.1.