Tula State University (Tula, Russia):

D. B. Belov, Cand. Eng.
O. I. Boriskin, Dr. Eng., Prof., Head of the Chair of Instrumental and Metrological Systems, Director of Polytechnic Institute
S. I. Solovyev, Cand. Eng., Associate Prof., e-mail: sergei59@bk.ru

The article considers the problems that arise in calculating the pitch and profile of thread milling cutters used in the processing of precise threaded surfaces, which consist in the need to simultaneously ensure the accuracy of the parameters of the teeth of the milling cutter and the favorable values of the cutting angles. In the traditional manufacture of such mills for processing the rear surfaces of the cutting teeth, a backing process is used, which, due to its dynamism due to the reciprocating movements of the grinding wheel and the head, does not always ensure a high pitch and tooth profile accuracy. In addition, the limited possibilities of the process of traditional occlusal not always allow creating favorable values of the cutting angles. These problems are effectively solved by applying a screw backing process to handle the lateral rear surfaces of the teeth of the threaded cutter. Screwing prevents the intermittent reciprocating motion of the backing grinding wheel and headstock, which determines the high accuracy of the pitch and profile of the teeth. The basic calculation formulas and results of calculation of the accuracy parameters (manufacturing errors) of the teeth of such a mill are given in the work. The basis of these calculations was the technique of processing the results of indirect measurements, taking into account the functional relationship between the directly measured parameters (in our case — the dimensions of the surfaces to be treated) and the indirect parameter sought (in our case, the profile angles of the cutter teeth and their pitch) and the accuracy (error) of the results of direct and indirect measurements (in our case, the accuracy of processing the right and left screw surfaces and the profile and pitch of the cutting teeth of the mill). The application of this approach in practice has shown that in the manufacture of the cutters in question on a thread grinder of model 5820 or models of the same level of accuracy of the design errors, the milling cutters do not exceed the values set by the standard and even provide some margin of accuracy.

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