Industry-oriented method for measuring the cutting forces based on the deflections of tool shank

This paper proposes an industry-convenient method of indirectly measuring cutting forces from the deflections of rotating tool shank. A displacement sensor is attached to the shank part of the tool for the purpose of probing the static and dynamic variations of the gap between the sensor and the rotating shank. Both air cut and actual cut are combined to remove the effect of misalignment between spindle and tool for the determination of accurate tool deflections under cutting load. To make the design as friendly as possible, new theoretical formula is derived to determine the required tool static stiffness by using substructure synthesis technique rather than the traditional inverse calibration method, which generally needs a reference dynamometer and thus is inconvenient in industry. A series of milling experimental tests with a high speed steel (HSS) and a carbide tools are carried out to demonstrate the proposed method. Dynamometer Kistler 9255B is also utilized in all experiments to measure cutting forces as reference for the sake of validating the correctness of the proposed method. Results show that cutting forces obtained by the proposed method are close to the reference values for both HSS and carbide tools. Especially, to check the reliability of the proposed method, classical cantilever beam theory is also discussed to calibrate the tool stiffness. Comparison turns out that the proposed method is a more reliable theoretical means to calibrate the required tool stiffness than cantilever beam theory-based approach.