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A technique and results of mathematical modeling and numerical and physical experiments involving the generation of the profi le of the helical surface of a concave worm by rotational turning of a multiblade tool with involute profi le of the cutting element are presented. The effi ciency of the production equipment used is improved and an increase in the performance of the process achieved.Globoid gearing with rectilinear profi les of the screw windings and wheel teeth in the principal axial cross-section are very common in Russian industry [1,2]. Globoid gearing is distinguished by 2-3-times greater load-carry capacity by comparison with cylindrical worm gears (with the same overall dimensions), their drawback being diffi culties in fabrication (sensitivity to manufacturing and assembly errors and complications in the manufacturing of tools for grooving the worm windings and teeth of a worm gearwheel [2]). The geometry of globoid gearing is calculated on the basis of the basic concave worm [1].Globoid gearing with basic involute cylindrical crown wheel are well known [3,4]. Such gears consist of a concave worm and ordinary cylindrical wheel [5] and possess a number of technological advantages, though also suffer from a drawback, i.e., that the diametrical dimensions of the cutting tool used to process the worm windings are comparable with the diametrical dimensions of the basic cylindrical wheel. Therefore, despite the obvious advantages of this type of globoid gearing, their production, especially in the range of center-to-center distances 315-1600 mm, has not been assimilated by Russian industry.Results of a calculation of the outer diameter of the cutting tool (used in processing of a concave worm with modulus 10 mm) are presented selectively in Table 1 determined from the expression (1) where d au is the outer diameter of the cutting tool; a, inter-axial distance of the globoid gearing; and d ƒ1 , diameter of the throat of the worm winding.Thus, the search for a more effi cient technology for manufacturing the parts of a globoid pair is a critical problem for the machine construction branch of industry.One of the effective approaches to the solution of this problem involves the use of the technology of rotational turning of the helical surface of a concave worm through constrained rotation of a multiblade tool with involute profi le. The technology is based on a method of cutting of concave worms by a multiblade tool the axis of which transmits motion along a

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