The subject matter of the research is issues related to the optimization of the technology for reconditioning large-size high precision gear rims of the drives of mining complexes, mine lifting equipment, heavy vehicles; these issues are a perspective trend for reducing the cost of reconditioning and operation of expensive unique equipment. The goal is to ensure intensifying production processes, increasing workloads and speeds, reducing the deterioration of high precision gear rims. The objective is to develop a new technology to optimize reconditioning large high precision gear rims. To achieve this, the following method is suggested -to machine gear rims after they have been surfaced by pre-milling with special hob cutters with a prominence and by final machining the teeth with special cutters equipped with hardmetal inserts that process teeth along the line of engagement, which does not require making full-length cutting teeth and increases the quality of machining, the durability of hardmetal milling cutters. The process of reconditioning of large high precision gear rims is a resource-saving technology, as compared with manufacturing new parts, this technology considerably reduces the cost of materials for manufacturing, decreases a number of process steps, reduces the cost of machining equipment, tools, cutting and measuring instruments. The smooth operation of a gear train can be ensured only at a constant gear ratio but due to manufacturing and operational errors, the gear ratio is not constant at every time, which intensify the deterioration of large high precision gear rims. The following results are obtained. The possibility and practicability of using hob cutters with a prominence (m = 20-28 mm) while rough cutting the worn and reconditioned large gear rims was proved. To obtain the necessary durability of rough milling cutters, it is recommended that the prominence angle be set within 8-10°. The use of hardmetal hob cutters for finishing makes it possible to increase the performance rate by 2 to 3 times as compared to high-speed cutters of other designs and to obtain the necessary quality and precision of manufacturing worn and reconditioned large gear rims. Conclusions. The technology for the optimization of reconditioning large high precision gear rims with the use of special and universal hardmetal single-and double-flute cutters that have both re-sharpened cutting elements and disposable rotary tools was developed and introduced.Keywords: new optimization technology, reconditioning large gear rims, high precision, hob cutters with a protuberance, special cutters, machining tooth along the line of engagement, improving the quality of machining.

The subject matter of the research in the article is the process of restoring the quality and accuracy of the working surface of the wheelsets of the main electric locomotives, electric sections. The purpose of the work is to develop a modeling method for a special shaped cutter with increased productivity, designed to process the profile of locomotive railway wheels taking into account the shaping processes, which is based on the theory of modeling the high-speed milling process through the shaping efficiency coefficient. The article solves the following tasks: substantiation of the importance of upgrading the most promising designs of "duplex" mills, taking into account the reduction of vibrations due to chip crushing, to increase tool wear resistance, machining accuracy, reduce tool readjustment time and, accordingly, reduce equipment downtime, increase processing productivity, determine the mathematical apparatus for calculating model parameters; development of a method for modeling and optimization of shaping processes in the processing of locomotive wheel sets. Such methods were used: fundamentals of system analysis, simulation method. The following results were obtained: the design of a "duplex" milling cutter with a predicted increase in resistance and increase in processing productivity due to modeling of forming processes with a decrease in the sliding angle by three to five times, which was not previously taken into account when designating and selecting cutting parameters, is provided. It is concluded that the model design of the cutter, taking into account "duplex" and the tribological process of modeling shaping during processing, can increase the resistance of the cutters and ensure the full operation of all cups of the cutter. The forming component of the cutting conditions was evaluated taking into account the coefficient of efficiency of the process of forming the surface layer of the machined wheel. The conclusion was made about the need to create new processes of shaping the design and modernization of tools. Various ways of modeling tool systems are considered. A method for creating a "duplex" cutter model is defined. A "duplex" mill is considered and design features of the algorithm for creating such tools are given. The functioning of the shaping parameters during the processing of locomotive wheelsets is formalized in the form of separate mathematical models and formulas, on the basis of which a method for modeling the process of increasing productivity and increasing the resistance of mills is described. Findings: Thus, a new method was created for modeling the process of shaping when machining wheel sets of locomotives with a "duplex" cutter with minimizing the cost of operating the tool and reducing the sliding angle on the arc of cutting the cutter cup with an increase in the quality and accuracy of processing, which makes it possible to significantly reduce the cost of preparing the production and increase processing efficiency.