Scientific Basis for the Substantiation of Process Regulations for the Micro-Cutting of Hardened Gears

Abstract

The paper considers scientific principles of technological procedure development for the selection and assignment of parameters of velocity machining by blade tool at gear milling with due regard to the required parameters of the gear surface layer. Optimum micro-cutting conditions are determined when full participation in stock removal of all mill teeth is provided. Technological regulation of selection and setting of machining parameters is spread for gear hobbing of the spur gear wheels with fine-modular and coarse-modular hardness (220...320 HV) and after heat treatment (HRC46...63). Correlation with essential parameters of the surface layer, cutting depth, feed, speed and radius of rounding of the cutting edge of milling cutters’ teeth is established. It is scientifically grounded, tested, and proved at what modes of cutting, the radius of rounding of cutting edge of the cutting tool is made metal removal at oncoming and passing high-speed micro milling. The process of determining of minimal sliding angle, or maximum value (without the use of coolant and with coolant), in which there is no micro-cutting process taking into account variation of variable parameters of cutting conditions and geometrical parameters of hobbing cutters is modelled. For the first time, we ascertained the relation between the sliding angle and the maximum contact angle of the mill tooth with the work surface, which allowed determine the efficiency of the shaping process through coefficient (without coolant and with coolant).

Evaluation of the Quality Parameters of the Surface Layer of Parts After Machining with Plasma Heating

“…The state of the surface layer material is characterized by its strain hardening, microstructure, magnitude and sign of residual stresses and the depth of their occurrence [1,5,16,19,27,29]. An analysis of the literature data on turning and milling made it possible to identify specific factors that affect the change in the height of micro-unevenness, microstructure and residual stresses in the surface layer of the workpiece [18,20,22,26,28,30,31]. (1) This formula is suitable for calculating Rzр when boring, drilling, countersinking, planning and milling using end mills.…”