Basic of forming the budget branches of economy of Ukraine is metallurgy. Rails concern to production of this branch. By manufacture of rails there is a necessity for formation of apertures on a rail for the further installation of the overlays used for connection of separate rails during installation of ways. As rails are made of special steel which is badly processed by tools from fast-cutting steel at processing apertures in rails the modular drills equipped by replaceable many-sided plates from a firm alloy have found wide application.
As shows operating experience of such tool, one of the reasons of an output of drills out of operation is breakage of the cutting plates resulting adverse operating conditions and presence not-counterbalanced of radial making force of cutting. The unbalanced radial component is caused by an asymmetrical arrangement of cutting plates in the case of a drill. To reduce to a minimum size of a unbalanced radial com-ponent and by that to provide more favorable operating conditions of a drill, it is necessary to establish cutting plates in the case of the tool under various corners.
With the purpose of definition of influence of geometrical parameters, in particu-lar the main forward corner and a corner of an inclination of the main cutting edge, on direction forces of cutting we had been developed the program in Mathcad environment. At races-couples of components of force of cutting the assumption that each edge of a cutting plate which participates in processing, works similarly to an edge of a detachable cutter. Result of work of the program is definition of a corner of a deviation which shows result forces from an axis of a drill depending on values of the main forward corner and a corner of an inclination of a cutting edge. Knowing position which shows result forces on each edge concerning an axis of the tool, we can define a unbalanced radial component. Thus, accepting various values of corners of installa-tion of cutting plates in the case of a drill, we can define geometrical parameters of the tool, at which value radial unbalanced minimally or equally to zero. In the further results of the given work will be used for optimization geometrical and design data of modular drills with replaceable many-sided plates.