Tkachuk I. Formation of magneto-abrasive tool with stable properties in the ring-type working gaps

The dissertation covers the problem solving of formation magneto-abrasive tool (MAT) with stable properties during the technological cycle of magneto-abrasive machining (MAM) of geometrically-complex details. In the paper were studied the influence of the magnetic field gradient, the type and characteristics of magneto-abrasive powders (MAP), size of workpieces on the formation conditions of MAT. Using the developed techniques, were experimentally determined the stages of structurization of the ferro-abrasive medium in the MAT, defined the compaction areas, which allow to forecast and effectively influence on the MAM. The structural-kinetic model was developed, which takes into account the specificities of process reformation of ferro-abrasive medium in magnetic field and allows reasonably determining the directions of the control of formation mechanisms of MAT. The developed method of MAM with using regenerative rod elements at angles of 35° - 45° allows to control the polishing properties of MAT and to perform uniform machining of long details in the ring-type working area. The possibility of increasing the quality parameters of the cutting tool (CT) made of high speed steel and hard alloy was proved, and namely: increase of surface hardness by 10 - 15 % depending on technological conditions of MAM, characteristics of MAP, which are used to formation the MAT; reducing roughness of working surfaces to a level of 0,1 - 0,5 µm at the original 0,2 - 0,9 µm; controlled formation of radiuses of cutting edge rounding in the range of 10 - 25 µm with complete removal from CT surface mikroburrs, polishing of a mikrotears. Operational durability of cutting tools increases in 2 or more times compared to unmachined and machined by MAT without stable properties during the time.