The design procedure of optimal multi-edge BTA deep-hole machining tools with unsymmetrically located cutters and preliminary test evidence are presented. Based on a mathematical model of cutting forces in terms of fundamental cutting parameters of the tool, a multivariable, nonlinear objective function was derived and modified to an unconstrained type with bounded decision variables. A numerical, direct search method, accelerated in distance, was selected to minimize the objective function. This procedure insures, on one hand, a predetermined cutting force resultant necessary for tool guidance; on the other hand, it minimizes the variation of cutting edge pressure. A relatively fast computer routine was adapted to provide the optimal tool parameters, which then were used to design cutting head prototypes. Two trepanning heads of three and two cutters were manufactured and tested at production facilities. The test results showed that the cutting force resultant was well predicted in both heads and that they were well guided. Much higher feed rates were possible compared to those achieved with single-edge tools without any loss of hole accuracy straightness or surface finish.

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