Computer 3D Modelling of Chip Geometry and Force Field in the Hobbing Process

Hrytsay, I.; Topchij, V.; Kuk, A.

Nowadays, the main method of machining the gears with a module in the range 1 - 25 mm, which are integral parts of modern machines, remains hobbing. Operations of the toothed crown processing determine the efficiency of the entire technological process of manufacturing gears. Thus, the time expenses and performance, the cost of the gears, and their final quality depend to a large extent on these indicators in operations of hobbing. Considering the importance of this process for mechanical engineering, considerable attention of scientists is devoted to its modelling. Chip parameters are the key source of information required for comprehensive and complete analysis of the hobbing process. Despite the large number of publications devoted to this problem, there is still no methodology for adequate reproduction of these parameters. Known methods and models are characterized by significant simplifications and do not reproduce completely the kinematics of this complex process. This article presents a new approach to graphical modelling of the chip parameters in the hobbing process, which is based on the analysis and synthesis of elementary kinematic motions, related to unit motions and displacements of the hob cutting elements in the process of removing the metal in the gap between the teeth of the processed gear. The algorithm for forming the instantaneous transitional surface between the gear teeth and the three-dimensional (3D) space geometry of the chips on all active teeth of the tool is implemented in the graphic system AutoCAD. The article presents the results of computer modelling of chips in the climb and up-cut hobbing with Archimedean and convoluted hobs. Complete information on the geometric structure of the cut layers provides the basis for complex and system modelling of this process at the level of separate racks, teeth and edge of a hob. In combination with the data on the intensity of plastic deformation, stresses and temperature obtained for the corresponding conditions of hobbing in the Deform system, data on the parameters of the cut layers create opportunities for predicting the heating and wear of cutting elements of a hob, their loading, strength of protective coatings, transient processes of the cutting force and temperature, designing of optimal technological processes of hobbing and management of these processes.


	Наукова періодика України		Ukrainian journal of mechanical engineering and materials science