Chencheva O. Improvement of motor-spindle for efficient drilling of carbon-plastics with tubular diamond drill bits

The dissertation is devoted to solving the actual scientific and technical problem of obtaining qualitative openings in carbon fiber plastics using tubular diamond drills. The hypothesis is scientifically based on the possibility of applying a cyclic flow of the instrument to preserve the diamond layer cutting properties and, consequently, to improve the quality of the treated surface. The model of interaction of a diamond-like tool with a non-uniform working medium environment is developed. The model takes into account the physical and mechanical properties of the material as a loose cavity medium, high-frequency and low-frequency perturbations on the contact surfaces due to the manifestation of the phenomena of periodic change in cutting efforts. The new technical solution of motor-spindle with the combined electric machines for the realization of linear-rotary movement of the working body with the possibility of controlling the frequency and amplitude of the axial loads of the drill is substantiated. A dynamic motor-spindle model is developed, which takes into account the presence of rotor supports, screw couplings, and also the final hardness of the working tool − drill. An original method of experimental research of a motor-spindle model with the combined electric machines created by means of 3D-printing was developed, the expediency of the use of additive technologies for the development of new technical solutions was substantiated. It is proved that the most effective cutting is done by setting the loading frequency, which corresponds to the elastic-plastic properties of the material being processed, which depend, including, on the orientation of the fibers. It is shown that the influence on the surface quality of high-frequency changes of torsional and axial loads caused by the structure of the material is manifested as much as possible in the event of a critical damage to the tool in the form of removing part of the abrasive layer from the surface.