Aparakin A. Improving the efficiency of finishing gear hobbing of cylindrical gears by changing the cutting scheme

The work is devoted to increasing the efficiency of finishing gear hobbing of involute gears of medium modules of 5...14 mm by changing the scheme of interaction of the cutting edge of the tool and the machined surface, and creating preconditions for the implementation of gear hobbing technology in flexible production. In turn, increasing the accuracy of gears helps to reduce vibration, noise levels and increase the durability of hydraulic machines. An analysis of current state of the method of gear hobbing and the contradictions between significant progress in the creation of machine systems and, despite numerous studies, not significant progress in improving the process of gear hobbing is presented. Research on directions of definition of energy consumption of processes of gear hobbing, the ways of reduction of distortions of geometrical form of the processed surface, influence of backlashes on kinematic accuracy of dividing circuits of rotary tables of gear hobbing machines according to the developed programmes and techniques are carried out. The obtained results of theoretical studies performed under modelling conditions indicated that to ensure the requirements for accuracy and quality of the treated surface during gear hobbing, the recommended system of interaction of the cutting edge and the treated surface is different from conventional gear hobbing. For this purpose, kinematic synthesis of the method of contour gear hobbing was performed on the basis of a fundamentally different interaction of the cutting edge and the treated surface. The results of theoretical studies of the process of form generation and energy consumption of processing indicate reduction in energy consumption by approximately 2,5 times due to reduction in cutting force while using a new method of gear hobbing. Experimental studies of cutting processes have been performed, which confirm the conclusions and data of theoretical studies on the poorer quality of the surface treated according to the model of conventional gear hobbing than the surface treated according to the model of contour gear hobbing. Experimental study of the formation of contour gear hobbing showed that the right and left profiles of the machined part are similar in the nature of the distortion of the involutegram, due to adequate cutting conditions. The conceptual design of the production gear centre for processing gears in the conditions of flexible production on the basis of contour gear hobbing is presented. The use of the method of differentiated preliminary cutting of intertooth cavities in order to create rational allowance for further processing is proposed and substantiated.